JPS60239523A - Manufacture of aromatic polyamide fiber - Google Patents

Abstract

PURPOSE:To manufacture an aromatic polyamide yarn having high tensile strength and high modulus and free from fluffs, without causing the fusion of the filaments, by applying specific inorganic fine powder to an aromatic polyamide yarn, treating the yarn with an aqueous dispersion of an inorganic compound capable of forming hydrated gel, and drawing the treated yarn under heating. CONSTITUTION:An aromatic polyamide yarn is immersed in an aqueous dispersion obtained by dispersing inorganic fine powder (A) composed mainly of hydrated magnesium silicate having an average particle diameter of <=5mu in an aqueous medium, treated with a liquid obtained by dispersing an inorganic compound (B) capable of forming hydrated gel (e.g. inorganic compound composed mainly of aluminum silicate), and is drawn under heating to obtain the objective yarn. The weight ratio of the fine powder A to the inorganic compound B is preferably 5/95-50/50, and the amount of the fine powder A attached to the yarn is preferably 0.02-2.0wt%.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing aromatic polyamide fibers. More specifically, when producing aromatic polyamide edge fibers with high tensile strength and high modulus by drawing at a high magnification under high temperature, fusion between single filaments is prevented and fuzz/or loops are prevented from occurring. Regarding the method.

<Prior Art> In recent years, various new materials have been developed and considered in response to the demand for high tensile strength and high modulus of fibers. For some of these, high-strength stretching at high temperatures is applied to achieve high performance, but in this case an undesirable phenomenon of fusion between single filaments occurs. In particular, when the number of filaments in the yarn increases, fusion increases, and as a result, not only the productivity of drawing decreases, but also the resulting drawn yarn becomes extremely inflexible.

As a method for preventing this fusion between single yarns, the present inventors previously proposed a method of applying a hydrated gel-forming inorganic compound to the surface of the fiber during hot drawing and/or heat treatment (Japanese Patent Application Laid-Open No. 58-2001).
(No. 54021) However, in this method, as the number of single yarns constituting the string bundle increases, the effect of preventing fusion between the single yarns decreases. It was found that the hydrated gel-forming inorganic compound adhering to the fiber surface dries to form a film on the fiber surface, resulting in the resulting fiber bundle becoming coarse and hard and lacking in flexibility. Furthermore, JP-A-50-157619 describes a method of applying inert inorganic fine particles such as talc, graphite, alumina, etc. to the fiber surface.
In this method, during hot drawing, the single fibers of the running yarn are extremely unstable and the drawing becomes extremely unstable, resulting in a lack of industrial productivity.

Furthermore, Japanese Patent Application Laid-Open No. 53-147811 proposes a method of uniformly depositing inorganic salts on the fiber surface by applying water-soluble inorganic salts as an aqueous solution to the fiber surface and drying.

However, even in this method, if the number of filaments constituting the fiber increases, not only will it not be possible to exhibit a sufficient anti-fusing effect, but also the yarn performance will not be fully exhibited because the inorganic salts inhibit smooth stretching of the fiber.

Furthermore, JP-A-54-15020 proposes a method of applying a non-melting polymer as an anti-fusing agent that does not need to be removed after hot drawing or heat treatment, but it is difficult to apply these polymers uniformly to the surface of m-fibers. In order to do this, it is necessary to apply the non-melting polymer by dissolving it in a specific solvent, and it is necessary to add complicated operations to remove and recover the solvent.

<Objective of the Invention> As mentioned above, the object of the present invention is to prevent the fusion between single yarns that occurs during hot drawing of aromatic polyamide fibers at high temperatures without impairing the drawability, and to improve the flexibility of the drawn yarn. The purpose of the present invention is to provide a method for producing high-quality aromatic polyamide fibers with improved properties and properties.

<Structure of the Invention> That is, the present invention is a method for producing aromatic polyamide fibers in which fine inorganic powder mainly composed of hydrated magnesium silicate with an average particle size of 5 μ or less is adhered to the fiber surface, and then the cord is soaked in water. This is a method for producing aromatic polyamide fibers, which is characterized by treating with an aqueous dispersion of a gel-forming inorganic compound and then hot stretching.

The aromatic polyamide fiber referred to in the present invention refers to a repeating unit constituting the polyamide having a molar ratio of 80 or more (preferably 9
0 molar coefficient or more) is NHAr+ NHCOArt CO
- A general term for fibers made of aromatic homopolyamide or aromatic copolyamide.

Regarding the manufacturing method of such aromatic polyamide, for example, British Patent No. 1501948, U.S. Patent No. 3
It is described in JP-A No. 738964, JP-A-49-100322, etc.

In the present invention, in the aromatic polyamide, at least 80 molar ratios of Arc and Ar2 are the following aromatic residues (g) and (B), and the molar ratio of the structural unit (B) is Aromatic copolyamides having a molecular weight of 10 to 40 are preferred.

Examples of such aromatic copolyamides include copolyamides composed of the following three monomer units.

Further, 301 mol% or more of the Ar, lAr,
Also suitable are aromatic copolyamides having the following aromatic residues and (B') and having a molar ratio of 10 to 40 units.

Examples of such aromatic copolyamides include copolyamides composed of the following three units:

An example of an inorganic fine powder containing hydrated magnesium as a main component is a fine powder generally called talc. In particular, it is necessary to use fine particles having an average particle size of 5 μm or less. If the particle size is larger than this, a large amount of fine powder must be used in order to uniformly cover the surface of the fibers and enhance the effect of preventing fusion, which is not preferable.

In addition, a hydrated gel-forming inorganic compound is one that forms a gel with almost no fluidity or semi-fluidity when the inorganic compound is impregnated with 5 times or more, preferably 10 times or more, of water. Refers to inorganic compounds. Specifically, examples include -yh silicates, such as inorganic compounds containing hydrated aluminum silicate as a main component. The inorganic fine powder mainly consisting of 1 ff of hydrated magnesium silicate attached to the fiber surface can suppress the contact between the single fibers and thereby prevent the fusion between the single fibers during high-temperature hot drawing. In addition, the fine powder improves the friction properties of the obtained drawn yarn, providing a drawn yarn with excellent workability in post-processing. On the other hand, when the hydrated gel-forming inorganic compound is attached to the K11l fiber together with water, the inorganic compound itself hydrates and swells to form a viscous gel, which improves the cohesiveness of the refilament. Furthermore, when the fiber is dried, a film is formed on the surface of the fiber, and this film further improves the cohesiveness of the yarn, so it can be used for spinning and drawing.

During post-processing, it is possible to prevent single yarns from becoming loose and raked during yarn running, and has excellent stretchability and post-processability! etc.

As for the method of applying the above-mentioned inorganic fine powder, it is possible to obtain an effect by applying a mixture of an inorganic powder and a hydrated gel-forming inorganic compound to the fibers, but first, the inorganic fine powder is applied to the fiber surface with hydrated magnesium silicate as a component. An even more remarkable effect can be obtained by applying a so-called two-stage application method in which a powder is deposited and then a hydrated gel-forming inorganic compound is deposited thereon.

For example, a fiber bundle is immersed in an aqueous medium such as water, methanol, 'r-tanol, or ethylene glycol, in which fine inorganic powder containing hydrated magnesium silicate is dispersed, and then squeezed with a squeezing roller. A method of immersing a hydrated gel-forming inorganic compound in an aqueous medium and squeezing it with a squeezing roller and drying it can be used. Note that it is also possible to use a method in which the ridge of the first stage of the crest is once dried.

The method of applying the inorganic fine powder to the fiber surface is not limited to the method of immersing the fiber in an aqueous dispersion; however, this method is excellent in that it can be uniformly applied to the surface of the single fiber.

The amount of 7w applied to the fibers can be adjusted by changing the dipping time, or by changing the concentration of the dispersion. Alternatively, a method of adjusting the amount of squeezing after dipping can also be used.

Note that other additives such as components that enhance the dispersibility of the inorganic fine powder may be used in combination with these dispersions as long as the object of the present invention is not impaired. NfIk attached to nine fibers of inorganic fine powder
is 0.01 to 5% by weight based on the weight of the fiber on an anhydrous basis.
, particularly preferably 0.05 to 2.0% by weight. If the applied amount is less than 0.01% by weight, no effect of #fiber surface modification such as prevention of fusion can be expected; on the other hand, even if it exceeds 5% by weight, no significant improvement in the fiber surface modification effect will be observed. Otherwise, fine powder may separate from the fibers during the process before the fibers are wound or during the process of processing the fibers, causing problems such as contaminating the thread guide. Furthermore, when the fiber is used as a rubber reinforcing material or a molded product reinforcing material (for FRP, etc.), the adhesiveness to rubber or resin is reduced.

The weight ratio of hydrated gel-forming inorganic (U compound) to fine powder mainly composed of hydrated magnesium silicate is 5/95 to 5.
A range of 0.0150 is preferred.

If the weight ratio of the hydrated gel-forming inorganic compound is less than 5, the effect of increasing fiber cohesiveness will be insufficient and looseness will occur between single yarns, which will cause loops, fuzz, etc. When the weight specific gravity of the hydrated gel-forming inorganic compound exceeds 50, the resulting drawn yarn becomes coarse and hard and has reduced flexibility. This is due to the fact that the hydrated gel-forming inorganic compound forms a hard film on the surface of the dried thick fibers.

In this way, an inorganic fine powder mainly composed of hydrated magnesium silicate, which has a remarkable anti-fusing effect, and a hydrated gel-forming inorganic compound, which works to improve the cohesiveness of yarns, are applied to the fibers in an appropriate ratio range. By applying the coating, it is possible to obtain a high-grade aromatic polyamide fine material with extremely little fusion and high flexibility without impairing stretchability.

<Effects of the Invention> By using the method of the present invention, fusion between single yarns can be prevented or significantly reduced without impairing drawability, and fluff and/or fuzz in the spinning process or post-processing process can be prevented.
Alternatively, the occurrence of a loop can be prevented.

Particularly remarkable effects can be obtained when the number of single yarns constituting the fiber bundle is large.

<Example> EXAMPLES The present invention will be specifically explained below with reference to Examples.

In addition, the main characteristic values used in the following examples were evaluated by the following method.

(1) Intrinsic viscosity of polymer1. V, (inheren
Using an Ostwald-type viscosity tube, the flow time of the solvent chisel is to (seconds), the flow time of the dilute polymer solution is t (seconds), and the polymer concentration in the dilute solution is C (fi/ 10 oIBJ). Then, it is expressed as. Unless otherwise specified, the solvent was 97.5% sulfuric acid, C
=0.5J7/10 orrJ, and measured at 30°C.

(2) Tensile properties of fibers 7) Using a tensile tester, the initial length of the fiber sample was 25α, the tensile rate was 10α/min, 20°G, 65%
The stretching curve is measured in an RH atmosphere. Stronger than this (
,9/de)', elongation (chi), Young's height (,9/de)
Calculate.

(3) Fusing degree (f) The value obtained by dividing the number of single filaments that should originally exist in the yarn by the number of filaments actually determined for the yarn after drawing or heat treatment is used. That is, it shows the average number of fused single filaments that one filament after drawing or heat treatment consists of. Measurements were taken at five locations, and the average value was taken as f.

Examples 1-3. Comparative Examples 1 to 5 N-methyl-containing calcium chloride (CaCAIt) was added to an aromatic copolyamide with 1V=3.5 composed of repeating units in the following molar ratio.
A 6% by weight polymer solution dissolved in 2-pyrrolidone (NMP) was extruded through a spinneret with a pore size of 0.3 mm and a number of holes of 1000 at a discharge rate of 1×ooE1 min. After running the spun yarn for 8 mm in air, it was heated to 50°C in NMP/water (
First-stage dispersion bath in which Chirilux (magnesium silicate) fine powder was coagulated at a rate of 340 ml/minute in a coagulation bath with a mixing ratio of 30/70% by weight and then washed in a 50°C water bath. (''After immersion, it was squeezed with a squeezing roller.7 Then, it was immersed in a second stage dispersion bath in which fine powder of osmos (aluminum silicate) was dispersed in water, and squeezed again with a squeezing roller.

Next, it was dried with hot air at 300°C. Directly heat the dried undrawn yarn to 360°C without winding it up.

Stretched 2.0 times on a hot plate with a length of 200σ, then 500
It was stretched 5 times on a hot plate with a length of 300 °G and a length of 300 °G. The fineness of the obtained drawn yarn was 1500 denier.

The above experiment was conducted by changing the higa of talc and osmos as shown in Table 1. The results obtained are shown in Table IK.

Note that the term "yarn running stability during drawing" as used herein refers to the evaluation of the unevenness of a single yarn in a running yarn during drawing based on the following standard pressure.

× Single yarn unevenness present ○ Single yarn unevenness extremely small ◎ Single yarn unevenness absent In addition, fuzz and loops of the drawn yarn were evaluated according to the following criteria by winding and visual inspection of the drawn yarn.

× Many △ Slightly present O None to extremely small In this way, talc is applied, and then osmos is applied, and the ratio of the applied amount is within the range of 9515 to 50150. Each granted separately, or 951
It is clear that the fibers are extremely superior in terms of fusing properties, stretchability, fluff, loops, fiber texture, etc., and exhibit a tactile effect, compared to those imparted with a specific gravity in a range other than 5 to 5 o 15 o.

Examples 4-5. Comparative Example 6 to 7 An experiment was carried out in the same manner as in Example 2, except that the average particle diameter of talc was changed as shown in Table 2. As for the performance of the obtained yarn, when the particle size of the talc exceeds 5μ, not only does the fusion property increase, but also the accumulation of fine powder on the yarn guiding guide after application of these inorganic fine powders increases, and this fine powder becomes entangled in the running yarn. Since yarn breakage causes fluff, it is sometimes necessary to interrupt the yarn spinning operation and clean the yarn guiding guide. The results are shown in Table 2.

E) rJ In Table 2, the evaluation of the deposition of inorganic fine powder on the yarn guiding guide is the result of visual judgment based on the following criteria after spinning for 12 hours.

○: No amount of deposit to very small amount △; Slightly present ×；〃〃〃Many

Claims (1)

[Claims] In the method for producing aromatic polyamide fibers, inorganic fine powder mainly composed of hydrated magnesium silicate with an average particle size of 5 μ or less is adhered to the fiber surface, and then a hydrated gel-forming inorganic compound is attached to the fiber surface. A method for producing aromatic polyamide fibers, which comprises treating with an aqueous dispersion and then hot stretching.