FR2480798A1 - PROCESS FOR FILTERING A POLY (POLYMETHYLENE TEREPHTHALAMIDE) FIBER OR POLYAMIDE 4 - Google Patents

Abstract

POLY (POLYMETHYLENE TEREPHTHALAMIDE) OR POLYAMIDE 4 SPINNING PROCESS. IT CONSISTS OF EXTRUDING A MELT MASS WITH SINGLE HOMOGENEOUS PHASE OF A POLY (POLYMETHYLENE TEREPHATALAMIDE) OR OF POLYAMIDE 4 AND OF WATER THROUGH A YARNS. FIBERS HAVING INTERESTING MECHANICAL PROPERTIES ARE OBTAINED WITHOUT SIGNIFICANT REDUCTION OF THE MOLECULAR MASS OF THE POLYMER WHICH COMPOSES THEM. APPLICATION TO THE MANUFACTURE OF TEXTILE FIBERS OR FOR THE REINFORCEMENT OF TIRES.

Description

The present invention relates to an improved process

  to prepare a fiber from polyethylene terephthalate

  phthalamides) or polyamide 4. It concerns more specifically

  First, a process in which a single phase melt of poly (polymethylene terephthalamide) or polyamide 4 and water is extruded through a spinneret, drawn for

  achieve a molecular orientation and subject to

  subsequent steps desired to obtain a fiber having

  interesting physical properties.

  Polypyrrolidone, or polyamide 4, is a polymer

  very interesting for many applications. An app.

  particularly advantageous cation would seem to be

  with this product a textile fiber which, given the

  the hydrophilic nature of polyamide 4, would be endowed with a

  taking high humidity and good aesthetic properties.

  Poly (polymethylene terephthalamide) constitutes a

  class of polyamides having a melting point and a temperature

  very high second-order transition structure, which

  make them potentially usable as tire fibers.

  in the field of clothing, for example

  in the manufacture of permanently folded textiles. The poly (he

  xamethylene terephthalamide, also known as

  polyamide 6T, is particularly interesting for these applications.

  plications and is a preferred species of this class

General.

  The polyamide 6T has a melting point of 371 ° C. Lors-

  when this polymer is heated to temperatures near its melting point, the decomposition of the polymer occurs

  before we get a usable melt. Professionals-

  ceded previously used to spin this polymer were

  wet spinning processes using sulfuric acid.

  furic acid concentrate as a solvent for the polymer and coagula-

  polymer in an aqueous medium. The formation of sulphate

  furic acid diluted in the coagulation bath was considered to be responsible for the hydrolysis of the polymer and a loss of

  significant molecular weight. Thus, although sulphuric acid

  concentrate used to dissolve the polymer does not

  not reduce the molecular weight of the polymer, the use of

  The addition of water to the coagulation medium caused a significant reduction in molecular weight. However, because of the unattractive nature of concentrated sulfuric acid as a solvent for the polymer, and other problems of spinning polyamide 6T and related polymers, the fiber obtained from these

  polymers has attracted only limited interest despite its

potential stages.

  Many efforts have been made in the past to

  obtaining a polyamide fiber 4 spun in the molten state.

  However, it has been found regularly that when the polymer is heated to temperatures near its melting point, a decomposition of the polymer occurs and

  that the polymer was essentially transformed back into its

  constituent name, pyrrolidone. This decomposition is

  easily demonstrated by the sharp reduction in

  of the melt and the impossibility of trans-

  to form the melt obtained in an apparatus of

fiber bonding.

  Although it is potentially possible to obtain polyamide fiber 4 by wet and dry spinning processes, the requirements imposed on the solvent of the polymer and

  solvent recovery systems to avoid pol-

  the environment and the high cost of solvents have

  rendered these processes unattractive. In addition, in

  coagulation regimes

  wet and dry, it is not certain that the poly-

  mother does not undergo degradation or hydrolysis leading to

  health and a product of inferior or unusable quality.

  To promote the poly (polymethylene) tere-

  phthalate and derive the potential benefits, and to

  to encourage the use of polyamide 4 fiber for

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  textiles, it is necessary to have a method of

  brication of these fibers avoiding the deficiencies of

  fiber forming processes while providing fiber with good physical properties. This would meet a long felt need and-would constitute a

important technical progress.

  For this purpose, the subject of the present invention is a

  process of preparing a fiber which consists in preparing a

  melt and homogeneous single phase of a poly (polymethyl)

  lene terephthalamide) or polypyrrolidone and water at a temperature above the boiling point of water at atmospheric pressure and at a temperature and

  which keep the water in a liquid state, the temperature

  is less than the degradation temperature of the

  polymer, to extrude this melt through a

  to form filaments, and to stretch the filaments

  obtained to achieve a molecular orientation.

  Surprisingly, the process does not cause any significant reduction in the molecular weight of the polymers subsequent to such treatment. It is also surprising

  appropriate molecular stretching of the molecules of the poly-

  The mother can be made without performing this stretching in an environment under vapor pressure. Despite the fact that

  nascent filaments solidify without the benefit of t-

  solidification zone under vapor pressure, it is also surprising that the obtuse fibers do not present

  no sheath-core structure with the adverse properties

she is training.

  The process of the invention makes it possible to spin poly (polymethylene terephthalamides) and polyamide 4

  sufficiently lower than their points of de-

  dimming so that we can operate safely and

  does not require unwanted solvents to liquefy

  lymères. As a result, the process of the invention constitutes

  kills an attractive route for the preparation of

  ly (polymethylene terephthalamide) and polypyrrolidone, and

  encourages them to take advantage of the advantageous properties of these

  fibers. The poly (polymethylene terephthalamides) which can be used in the process of the invention correspond to the formula in which the units are

C NH CH24 NH-

  these o o n is an integer equal to about 2 to 12, preferably about 4 to 8, and more preferably to 6. Polymers containing

  these reasons can be prepared by polycondensation of the

  terephthalic acid and a polymethylenediamine

  standard operating procedures. Coreactive agents such as caprolactane, etc. can be used to provide

  additional patterns in the polymer, in

  which do not diminish favorable properties of the fiber obtained. Some of the coreagents can be used to lower the melting point of the polymer obtained or to

  provide other characteristics not obtained by the

  pairing of terephthalic acid and polymethylene

diamine used alone.

  Polymers used as fillers in

  the present process can be prepared in bulk or under

  very classic shapes. Since polymers and co-polymers

  polymers of poly (polymethylene terephthalimide) are known, as are polypyrrolidones, it is not necessary

  to discuss further the preparation and the nature. Some

  Usable polymers of the type described will generally have

  molecular weights in the range of about 6,000 to

  100,000 or more, usually about 10,000 to 50,000, the main criteria being that they form with

  water of single-phase melts.

  When treatment is carried out in accordance with the

  first, a homogeneous single-phase melt of poly (polymethylene terephthalamide) or

  polypyrrolidone and water. The amount of water required

  to obtain the homogeneous single-phase melt will generally be in the range of about 10 to 90% by

  weight relative to the total weight of polymer and water. Lors-

  poly (polymethylene terephthalamide) is used,

  in general about 5 to 25%, a pre-

  about 7 to 15%, on the same basis. With the po-

  lypyrrolidone, it is generally used approximately 5 to 15%

  in weight. The water content will depend on the temperature in the

  which one operates, of the molecular weight of the polymer and of

  other factors. A useful method for indicating the composi-

  appropriate water-polymerization is to construct a dia-

  gram of phases. However, there is considerable latitude

  in the choice of the polymer-water composition, in par-

  especially when operating at high temperature, and consequently

  homogeneous single phase melts can be

  exist for a whole series of water contents.

  In general, the solid polymer is mixed with water and

  the polymer absorbs the water so that a poly-

  wet mother. This solid wet polymer is then trans-

  formed into a melt, usually by means of an extrusion

  screwdriver. The extruder heats and compresses the composition

  polymer-water and provides the single-phase melt.

  gene at an appropriate temperature and pressure,

  usually above the spontaneous pressure, for the ex-

  trusion. As indicated, the polymer composition

  The water will form the desired melt at a higher temperature.

  above the boiling point of the water under the pressure

  mospheric and at a temperature below the degradation temperature of the polymer. To maintain the water in a liquid state, pressure at least equal to the spontaneous pressure is required, and higher pressures will generally occur due to compression. It is generally preferable to prepare the melt at a temperature

  at least about 10 ° C above the minimum melting point

  mum of the polymer-water composition to ensure homogeneity

  tee of the melt. At temperatures above the minimum melting point of the polymer-water composition, there will be a variety of water contents that will provide a single-phase melt, and a larger margin.

  in the water content-will be possible.-The amount of water

  The use of the polymer with the polymer class will vary somewhat with the composition of the polymer, its molecular weight, the operating conditions, etc. Generally, the melt is formed at a temperature in the range of about 170 to about 250 C, preferably about 180 and 220 C, when

  uses poly (polymethylene terephthalamides), and between

  165 and 175 ° C when using polypyrrolidone.

  The melting point of the polypyrrolidone is 240-260 C.

  When the homogeneous melt & single phase is prepared, it is extruded & molten through a die

  to form filaments. Usually, the pressure

  The extruder is sufficient for extrusion, but additional pumps or pressurizing devices may be used if desired. The die must contain fiber-forming orifices of appropriate size

  to give filaments of textile denier when the treatment

  is finished. Extrusion can be done directly -

  in the atmosphere, although other environments may be used if desired. For polypyrrolidone,

  preferably uses extrusion into the atmosphere.

  When using polyamide 4, at the time when the former

  filamentary trudate emerges from the industry into the atmosphere, there is only a weak or no tendency

  fast water vapor filaments. It is thought that this result

  The result is that the resultant polyamide filaments 4 have a homogeneous, transparent structure which is practically free from

  sheath-core structure, voids, density gradient following

  the cross-section of the filaments, reflectance

  internal and other imperfections caused by a libera-

  uncontrolled supply of water vapor from nascent filaments. After formation of the filaments by extrusion, they are

  stretches in accordance with the invention to achieve

  be a molecular orientation. This stretching

  improvement of the physical properties of the filaments and

  also leads to a reduction of their size. Stretching can be done to a limited extent by means

  conventional, for example with drawing cylinders etc ...

  To achieve additional stretching, the filaments can be stretched together with a projection of air

  hot on these. In replacement or in addition to this

  ration, the filaments can be stretched over a heated surface

  fairy such as a plate, an axis or a cylinder. This stretching can be carried out in one or more stages, during the

  transformation of filaments during spinning.

  When poly (polymethylene terephthalate

  mids), although it is possible to obtain pre-

  feeling good physical properties by extruding mass

  single phase melts in the atmosphere, it is generally preferred to

  neral extrude the melt into a solidification zone

  under pressure of steam maintained with steam

  at a temperature of about 10 0C to about 50 OC

  below the minimum melting temperature of the composi-

  polymerization-water, because this treatment allows a higher degree of stretching while the filaments remain

  in the solidification zone. When stretching is effected

  killed on filaments formed in the atmosphere, it is usual

  it is obtained by drawing on a heated surface such as a plate, an axis or a cylinder. This type of stretching can also be accomplished by spinning in hot air only,

  or in combination with stretching on a heated surface.

  It is also possible to perform an improved drawing by extruding the filaments in hot water, which can

  also regulate the water release of the extrudates.

  Although no further processing of the filaments is necessary in the process of the invention, additional processing operations can be carried out. For example, post-stretching, drying,

  relaxation, a wave, etc. It is usually advantageous

  tageux to dry the filaments in regulated conditions

  temperature and humidity to improve their transparency.

  this. This is preferably done at temperatures of

  dry bulb in the range of 110 to 180 ° C and at temperatures of

  eratures of the wet bulb in the range of about 60 to C. After drying, it is generally useful also

  to subject the filaments to relaxation in

  fear under pressure in order to make a withdrawal of

  5% to 40%, as this treatment tends to provide a balance

  favorable physical properties.

  The following non-limiting examples are given in

  As an illustration of the invention.

EXAMPLE 1

  A poly (hexamethylene terephthalamide), or polyamide 6T, having a specific relative viscosity in sulfuric acid, of 1.7, is prepared in the form of a fine powder.

  of a particle size of less than 100 microns. We are

  physically binds to the polymer of water in a proportion

  about 20% of the overall weight, to obtain a powder

  flowing freely, of dry aspect. This material is brought

  the shape of dense cylindrical granules 9.5 mm in diameter

  weighing about 2.5 g and containing 19% water. We introduce

  these granules into an Instron equilibrium capillary rheometer.

  a single capillary die of 85 microns of dia-

  meter and a protective filter pad. The temperature of the rheometer is 200 ° C. The rheometer sleeve is closed tightly immediately after the granules are introduced by means of the piston rod, and the charge is maintained below a pressure of 3450 KPa for 5 minutes. minutes. At the end of this time, the piston control is turned on to deliver a polymeric melt through the capillary at a linear velocity of about 9 m / min. It comes out a transparent filament that can be stretched in the air at the

  hand out of the capillary of the sector, as it is

  typically the case for melts forming fibers.

  When determining its relative viscosity, the filament ex-

  trude is found to contain a polymer which has undergone a

  negligible cation of its molecular mass in relation to this

the starting polymer.

EXAMPLE 2

  The polymer of Example 1 is prepared in the form of a coarse granule having a particle size of between 0.25 and 0.75 mm. This granulate is mixed with water in a double-chamber mixer at room temperature to give a free-flowing solid of dry appearance containing about 8% water. This material is extruded in the form of granules in an Instron rheometer at 200 ° C. through a single 200 micron spinneret at a linear velocity of 5 m / ins which gives a transparent filament having the filament of Example 1 as a filament.

  excellent stretching in the air. The apparent viscosity at the

  melted state, measured at an apparent shear rate of

000 s 1, is about 160 Pa.s.

EXAMPLE 3

  The polymer of Example 2 is sent to an extruder

  19 mm single-screw machine connected to a die by a melt feed system. The die feeds into a steam chamber containing 3 stages of draw rolls and a closure device to allow the exit of the wire

  stretched in an external receiving device.

  The textzuder being first fed with a polymer

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  "Starter" acrylonitrile containing about 15% water and stably delivering a polymer melt

  of acrylonitrile hydrated to the die, the poly-

  hydrated mother of Example 2 in the feed hopper.

  Progressively from 100% polyacrylonitrile-water to 100% polyamide 6T-water, and adjust the temperatures of the extruder to achieve a temperature of the mass

fondue of 200 C.

  Hydrated polyamide 6T is sent at a rate of 7.4 gAnin

  to the die containing 37 capillaries of 200 micron diameters

  meter each. With the steam chamber under a saturated vapor pressure of -69 kPa, the spun filaments are stretched at a total draw ratio of 60 to give a min.

  a total denier of 150, or 4.1 denier per filament. In the dy-

  Instron namometer, this mache proves to be a force

  about 2 g / denier and an elongation at rup-

about 20%.

EXAMPLE 4

  The procedure of Example 3 is repeated in all

  material details, except that the room is left to

  open fear of the atmosphere and no steam. It is found that the spun filaments exhibit good air drawing thinning, giving rise to draw ratios of at least 10%, and that the resultant filament can be further stretched by passing over a web.

heated surface.

  In each of the above examples, the fiber obtained has a homogeneous, transparent structure, with no sign of

sheath-core structure.

  In the following examples, the extrusion of the fiber-forming polyamide composition 4 is studied by means of

  an Instron capillary rheometer equipped with a capillary

* single pillar of 100 microns in diameter and buffer

  protective filter. Since the quantity of polyamide 4

  in the trade is extremely limited, the quantity

  fiber that could be produced was insufficient to

  samples other than a simple test

  moth. It is known, however, from other studies involving many other fiber-forming polymers, that there is an excellent correlation between Instron capillary rheometer performances and those obtained from

  equipment for manufacturing fibers on an industrial scale

  trielle. In fact, when considering modifications in polymer compositions in industrial fiber manufacturing processes, the general practice is to evaluate

  the modified polymer composition using the rheometer

  Instron capillary to predict its ultimate performance

  the. Accordingly, the results given in the examples, although inherently descriptive, give a very good indication of the results obtained in large scale installations and represent the practice of the present invention.

COMPARATIVE EXAMPLE

  The polymer used in this example is a dry polyamide 4 (polypyrrolidone). A sample of this polymer in

  0.5% solution in formic acid has a

  relative coseness of 1.61. In a capillary rheometer

  equipped with a single 100 micron die

  a part of the dry polymer. The polymer is heated to 240.degree.

  260 C until a melt is formed. The melt obtained is a fluid fluid consisting mainly of pyrrolidone monomer. By extrusion of this melt

  fluid, no fiber can be formed.

EXAMPLE 5

  The same polymer is used as in the comparative example

  ratif. The Instron capillary rheometer described in Comparative Example was charged with a mixture of 90 parts of polymer and 10 parts of water. After heating the polymer-water composition at a temperature of 170 ° C., a homogeneous single-phase melt is formed. This melt is spun through the capillary into the atmosphere and forms a fiber. When the nascent filament is formed, it is stretched by hand from the orifice. Although he is not

  it is not possible to measure the degree of stretch achieved by this

  In the drawing technique, it appears possible to carry out an adequate stretch giving good fibrous properties. The fiber is practically transparent and seems to have a

  homogeneous structure, practically free of voids, structural

  sheath-core, density gradient and super-

  ficial. Manual tests indicate good toughness

  both on the right fiber and on the fiber forming a loop.

  A sample of the fiber is dissolved in formic acid.

  than in order to obtain a 0.5% solution. The viscosity

  the polymer thus obtained is 1.56, which indicates

  that no significant reduction in molecular weight

  of the polymer resulted from the process of

fibers.

Claims (6)

  1 - Process for the preparation of fibers, characterized in that a homogeneous single-phase melt is prepared   a polymer comprising a poly (polymethylene terephthalate)   mide) or polypyrrolidone and water at a temperature above the boiling point of water at atmospheric pressure and at a temperature and pressure which maintain the water in a liquid state, the temperature being less than the degradation temperature of the polymer, by extruding this melt through a die to form a filament and by stretching the filaments   obtained to achieve a molecular orientation.   2 - Process according to claim 1, characterized in   the polymer is poly (hexamethylene terephthalamide).   3 - Process according to claim 2, characterized in that the extrusion is carried out directly in an area   under steam pressure in which the operation is carried out ratiôn of drawing.   4 - Process according to claim 2, characterized in that the water content of the polymer-water melt is about 7 to 15%.   - Process according to claim 4, characterized in that the temperature of the melt is about 180 at 220 C.   6 - Process according to claim 1, characterized in   what this polymer is polypyrrolidone.   7 - Process according to claim 6, characterized in that the melt & single phase contains about 5 & 12% by weight of water.   -8 - Process according to claim 6, characterized in that the temperature of the melt is approximately 165 A 175 C.