JPH0617316A - Aromatic polyamide fiber - Google Patents

Abstract

PURPOSE:To provide a high-tenacity aromatic polyamide fiber having light resistance improved by the ultraviolet-reflecting, shielding, and absorbing actions of inorganic particles having a high refractive index. CONSTITUTION:The objective aromatic polyamide fiber having a single fiber fineness of 0.5-50de and mechanical properties satisfying the following conditions contains (at least in the surface layer of the fiber) 0.1-5wt.% (based on the fiber) of inorganic particles having refractive index of >=2.0 and an average particle diameter of <=0.3mum. Strength, >=18g/de; elongation, >=3.5%; initial modulus, >=450g/de.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aromatic polyamide fiber having excellent light resistance.

[0002]

2. Description of the Related Art Para-oriented aromatic polyamide fibers are used in various fields as industrial fibers due to their excellent mechanical properties, but their light resistance is not always at a satisfactory level, and they are exposed to sunlight for use. In this case, there is a problem that the physical properties of the fiber tend to deteriorate.

Although the cause of this is not fully understood, there is a possibility that an amide bond is cleaved and decomposed by a photochemical reaction in the presence of water, a Fries rearrangement reaction occurs in the amide bond, and radicals are generated by oxidation. It is considered that there is a possibility that it will be generated and decomposed.

Therefore, in the case of ropes or nets of industrial materials, it is necessary to cover the surface with other fibers or resins to take measures to suppress light resistance deterioration. In addition, especially when developing into lightweight and high-strength textiles for sports clothing that utilize ultrafine fibers,
Aromatic polyamide fibers having good light resistance have been desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a high-strength aromatic polyamide fiber having improved light resistance due to the reflection, blocking, and absorption of ultraviolet rays of inorganic particles having a high refractive index. is there.

[0006]

[Means for Solving the Problems] The following measures have been proposed so far as measures for improving the light resistance of aramid fibers, but at the present time they have not been sufficiently satisfactory. That is, a benzotriazole-based or substituted benzophenone-based UV absorber is used in an amount of 0.01 μm in 2 to 6% fiber.
In the method of uniformly dispersing and blending so as not to have agglomerates (US Pat. No. 3,888,821), the agent is likely to be thermally deteriorated during the high temperature heat treatment step and the agent is evenly distributed to the inside of the fiber, resulting in low addition efficiency. There is a problem. Further, a method of canceling discoloration due to light resistance by adding 0.02 to 10% of a photobleaching pigment (JP-A-2-2292).
No. 81), it is theoretically difficult and there is a problem that the hue is limited. In the method of N-aromatic acylating an amide group to modify it into an imide group (JP-A-2-178324), it is necessary to carry out N-aromatic acylation with benzoyl chloride or the like in a state of being dissolved in an aromatic polyamide solvent. Therefore, the process becomes long.

As a result of diligent studies on measures for improving light resistance by reflecting ultraviolet rays and effectively adding an absorber, the presence of specific inorganic particles in at least the surface layer of the fiber impairs the mechanical properties of the fiber. The present invention has been accomplished by finding that aramid fibers having excellent light resistance can be obtained without any problem.

That is, according to the present invention, at least the surface layer portion of the fiber contains inorganic particles having a refractive index of 2.0 or more and an average particle diameter of 0.3 μ or less in an amount of 0.1% to 5% by weight of the fiber, and the single yarn fineness is An aromatic polyamide fiber having a denier of 0.5 to 50 and a mechanical property satisfying the following range. Strength: 18 g / de or more Elongation: 3.5% or more Initial modulus: 450 g / de or more.

The present invention will be described in detail below. The aromatic polyamide which is the object of the present invention has a repeating unit of 80
An aromatic polyamide or an aromatic copolyamide having the following repeating units accounts for not less than mol%, preferably not less than 90 mol%.

[0010]

[Chemical 1]

(Here, Ar1 and Ar2 are the same or different aromatic residues selected from the following groups, provided that the hydrogen atom of the aromatic residue is substituted with a halogen atom or a lower alkyl group. May be.)

[0012]

[Chemical 2]

X is selected from the following residues.

[0014]

[Chemical 3]

The method for producing the aromatic polyamide is described in, for example, British Patent No. 1501948, US Pat. No. 3,738,964, and Japanese Patent Laid-Open No. 49-100522.

The distribution position of the inorganic particles in the fiber is at least the surface layer portion of the fiber. It may be the whole fiber, but it is more effective if it is concentrated in the surface layer. It is preferably a surface layer portion having a fiber radius of 20% or less, and more preferably a fiber layer radius of 10% or less. It may be the fiber surface. If the fiber is evenly distributed throughout the fiber, that is, in the fiber cross section, the efficiency of addition is low whether it is reflection of UV light or absorption, so it is necessary to add a high concentration, and in this case the physical properties of the fiber are adversely affected. It is necessary to pay close attention to the reduction of the particle size of the inorganic particles and the reduction of coarse agglomerated particles so as not to affect it. As a measure to make the distribution of inorganic particles substantially in the fiber surface layer, a method of blending a high concentration of inorganic particles into a sheath component as a core-sheath type composite spinning, a method of impregnating inorganic particles from the outside such as dyeing, and other swelling Inorganic particles are applied to the fibers in a state and then dried and shrunk to incorporate the inorganic particles into the surface layer, static electricity is applied to the fiber surface and then fixed by fusion or adhesion, and the inorganic particles are blended in a high concentration. There is a method of coating resin on the fiber surface.

The refractive index of the inorganic particles is 2.0 or more. Generally, the reflectance of light is ρ = ((n2-n1) / (n2 + n
1)) ² , (where ni is the refractive index of the i-th layer) and the refractive index of the added particles is low, the reflection efficiency of ultraviolet rays decreases, and as a result, the deterioration of the fibers due to exposure to ultraviolet rays increases. As the inorganic particles having a refractive index of 2.0 or more, rutile type titanium oxide,
Anatase type titanium oxide, zinc white, cadmium red,
Red, red iron oxide, middle yellow lead, cadmium yellow, yellow iron oxide, chrome vermilion, etc.

In addition to the above-mentioned inorganic particles, an inorganic ultraviolet absorber (carbon black, lead chromate,
(Chromium oxide, etc.), organic UV absorbers, radical scavengers (phenolic antioxidants, phosphorus antioxidants, amine antioxidants, hindered amines) are more effective in combination.

The average particle size of the inorganic substance to be added is 0.3 μm or less. If the particle size becomes large, the additive acts as a defective foreign matter, causing fluff or yarn breakage due to single yarn breakage, which is not preferable.

The addition concentration of the inorganic particles is 0.1% or more and 5% or less. If it is less than 0.1%, there is almost no ultraviolet ray reflection or shielding effect, and if it exceeds 5%, the effect as foreign matter increases and the physical properties deteriorate.

The single yarn fineness of the fiber is 0.5 denier or more and 50.
It is less than or equal to denier. If the denier is less than 0.5 denier, the added particles act as defective foreign matter and the spinnability becomes unstable. Further, since the specific surface area of the fiber becomes large, the fiber is liable to be deteriorated by light resistance, and as a result, the addition amount of particles is increased, and the addition of inorganic particles further adversely affects foreign matter as a foreign substance, which is not preferable. If it exceeds 50 denier, the fiber has a small specific surface area and is less susceptible to light resistance deterioration, but the small specific surface area in the yarn making process tends to cause incomplete coagulation, resulting in disturbed process conditions in the washing and drawing processes and physical properties. Easy to fall.

The strength is 18 g / d or more. The higher the strength is, the more preferable it is, but the strength tends to decrease as the concentration of the additive is increased, and if it is less than 18 g / d, the characteristics of the aramid fiber as a high strength fiber are lost.

The elongation is 3.5% or more. If it is less than 3.5%, twisting strain becomes large when used by twisting,
The strength utilization of the twisted cord is reduced.

The initial modulus is 450 g / d or more. When it is less than 450 g / d, the characteristics as a high modulus fiber are lost.

[0025]

EXAMPLES The present invention will be described below with reference to examples. The polymer solution (dope) used in the yarn making test was prepared by the following solution polymerization method. Preparation of dope 205 l of N-methyl-2-pyrrolidone (hereinafter referred to as NMP) having a water content of about 20 ppm was put into a mixing tank having an anchor-shaped stirring blade in which nitrogen was flown, and 2764 g of paraphenylenediamine and 3, 5114 g of 4'-diaminodiphenyl ether was precisely weighed and added, and dissolved. The temperature of this diamine solution was 30 ° C. and the stirring speed was 64.
Terephthalic acid chloride 1032 at times / minute
0 g was precisely weighed and charged. The temperature of the solution rose to 53 ° C. due to the heat of reaction and was then heated for 60 minutes to 85 ° C. The polymerization reaction was terminated when the increase in the viscosity of the solution was completed by continuing stirring at 85 ° C for a further 15 minutes. After this, 22.5 wt% NMP slurry of calcium hydroxide 1
Add 6.8 kg and continue stirring for 20 minutes to reach pH 5.4.
The dope was filtered through a filter having an opening of 20 microns to complete the preparation of a polymer solution having a polymer concentration of 6% (hereinafter referred to as a dope).

[0026]

Comparative Example 1 The light resistance of a fiber obtained by spinning the dope prepared by the above polymerization method under the following conditions was evaluated. Spinning is a dry jet spinning method, the nozzle shape is a round cross section with a diameter of 0.3 mm, and a 1000-hole spinneret is used. The yarn is spun at a discharge rate of 1350 g / min and a dope temperature of 107 ° C., then at 50 ° C. in a 30% NMP aqueous solution. After coagulation with water, drawing from the coagulation bath at a spinning speed of 47 m / min, washing with water, application of a hydrated gel-forming inorganic compound, drying and heat stretching to 500 m
The product was wound at 1 / min to obtain a yarn of 1500 denier. The physical properties of this aramid fiber were as follows. Total fineness: 1502 denier Yarn strength: 42.7 kg Strength: 28.4 g / d Breaking elongation: 4.54% Modulus: 577 g / d This sample was evaluated for sunshine light resistance deterioration for 63 degrees * 300 hours, and the residual strength was found to be 16.8kg, maintenance rate is 39
%Met. As a result of evaluating the carbon fade fade resistance deterioration of the same sample at 63 degrees for 300 hours, the remaining strength is 17.9 kg,
The maintenance rate was 42%.

[0027]

Example 1 In the yarn making method shown in Comparative Example 1, the hydrated gel-forming inorganic material has a refractive index of about 2.7 and an average particle diameter of 0.0.
After applying 2% of 2μ of rutile-type titanium oxide ultrafine particles (surface treatment with silica) to the undrawn yarn after washing with water, the product was dried and hot-drawn, and the product was wound up at 500 m / min 1500 I got a denier thread. The physical properties of this aramid fiber were as follows. Denier: 1503 Denier yarn Strength: 43.3 kg Strength: 28.8 g / d Elongation at break: 4.60% Modulus: 583 g / d TiO2 concentration in fiber: 0.25% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that the surface layer was substantially within 5%. As a result of evaluating the sunshine light resistance deterioration of this sample for 63 degrees * 300 hours, the residual strength was 21.5 kg and the maintenance rate was 50%. The same sample was evaluated for carbon fade fade resistance to light of 63 ° * 300 hours. As a result, the residual strength was 21.2 kg and the maintenance rate was 49%.

[0028]

Example 2 In comparison with Comparative Example 1, ultrafine particles of rutile type titanium oxide having a refractive index of about 2.7 and an average particle size of 0.04 μ (surface-treated with alumina silica) were used as NMP slurry in the dope to be used. In the same manner as in Comparative Example 1, except that only a dope prepared by adding 3% of the polymer ratio and uniformly mixed was used, the yarn was spun. The physical properties of this aramid fiber were as follows. Denier: 1509 Denier yarn Strength: 38.8 kg Strength: 25.7 g / d Elongation at break: 4.43% Modulus: 571 g / d TiO2 concentration in fiber: 3.0% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that it was almost uniform. This sample is 63 degrees * 3
As a result of evaluating the sunshine light resistance deterioration for 00 hours, the residual strength was 18.6 kg and the maintenance rate was 48%. The same sample was evaluated for carbon fade fade resistance to light of 63 ° * 300 hours. As a result, the residual strength was 17.8 kg and the maintenance rate was 46%.

[0029]

Example 3 In the yarn making method shown in Comparative Example 1, the hydrated gel-forming inorganic material has a refractive index of about 2.7 and an average particle diameter of 0.0.
5 μm of ultrafine particles of rutile type titanium oxide (surface treated with aluminum oxide) was added as 3% hydrated gel to the undrawn yarn after washing with water, followed by drying and hot drawing at 500 m / min. The product was wound to obtain 1500 denier yarn. The physical properties of this aramid fiber were as follows. Denier: 1511 Denier yarn Strength: 42.5 kg Strength: 28.1 g / d Breaking elongation: 4.75% Modulus: 598 g / d TiO2 concentration in the fiber: 0.34% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that the surface layer was substantially within 5%. As a result of evaluating the sunshine light resistance deterioration of this sample for 63 degrees * 300 hours, the residual strength was 22.1 kg and the maintenance rate was 52%. The same sample was evaluated for carbon fade fade resistance deterioration of 63 ° * 300 hours. As a result, the residual strength was 20.4 kg and the maintenance rate was 48%.

[0030]

EXAMPLE 4 In contrast to Example 2, the dope to be used was carbon black having a primary particle size of 60 mμ and a polymer ratio of 1.5.
%, And the other conditions were the same as in Example 3 except that only the dope was added and uniformly mixed. The physical properties of the obtained aramid fiber were as follows. Denier: 1531
Denier yarn Tensile strength: 38.0 kg Strength: 24.8 g / d Elongation at break: 4.30% Modulus: 584 g / d TiO2 concentration in fiber: 0.18% The distribution of TiO2 in the fiber cross-section direction is the surface layer 5 It was confirmed by XMA that it was substantially within%. It was confirmed by a transmission electron microscope that the carbon particles were uniformly distributed in the fiber. This sample is 63 degrees * 300
As a result of evaluating the sunshine light resistance deterioration of time, the residual strength was 30.0 kg and the maintenance rate was 79%. 6 same samples
As a result of evaluating the carbon fade fade light resistance deterioration at 3 degrees * 300 hours, the residual strength was 27.0 kg and the maintenance rate was 71%.

[0031]

[Example 5] In contrast to Example 4, a hindered amine (CHIMAGESO, CHIMASSORB94) was used as a product finishing oil.
Other conditions were the same as in Example 3 as a finishing oil agent containing 4% of 4) added. The physical properties of the obtained aramid fiber were as follows. Denier: 1506 Denier yarn Strength: 34.9 kg Strength: 23.2 g / d Elongation at break: 3.98% Modulus: 584 g / d TiO2 concentration in fiber: 0.14% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that the surface layer was substantially within 5%. It was confirmed by a transmission electron microscope that the carbon particles were uniformly distributed in the fiber. This sample is 63 degrees * 300
As a result of evaluating the sunshine light resistance deterioration of time, the residual strength was 28.3 kg and the maintenance rate was 81%. 6 same samples
As a result of carbon fade fade resistance deterioration evaluation of 3 times * 300 hours, the remaining strength was 24.4 kg and the maintenance rate was 70%.

[0032]

[Example 6] In contrast to Example 5, a benzotriazole-based UV absorber (Ciba Geigy Co., Ltd., TINU) was used as a product finishing oil agent.
Other conditions were the same as in Example 3 as the finishing oil agent containing 2% of VIN213). The physical properties of the obtained aramid fiber were as follows. Denier: 1548 Denier yarn Strength: 39.3 kg Strength: 25.4 g / d Elongation at break: 4.39% Modulus: 564 g / d TiO2 concentration in fiber: 0.20% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that the surface layer was substantially within 5%. It was confirmed by a transmission electron microscope that the carbon particles were uniformly distributed in the fiber. This sample is 63 degrees * 300
As a result of evaluating the sunshine light resistance deterioration of time, the residual strength was 31.0 kg and the maintenance rate was 79%. 6 same samples
As a result of evaluating the carbon fade light resistance deterioration of 3 degrees * 300 hours, the residual strength was 28.7 kg and the maintenance rate was 73%.

[0033]

[Comparative Example 2] In the yarn making method shown in Example 2, the additive to the dope used was a silica having a refractive index of about 1.6 and an average particle diameter of 0.7μ was 2%, and the other conditions were the same. did. The physical properties of the obtained aramid fiber were as follows. Denier: 1503 Denier yarn Strength: 32.3 kg Strength: 21.5 g / d Breaking elongation: 4.10% Modulus: 523 g / d TiO2 concentration in fiber: 0.35% The distribution of TiO2 in the fiber cross-section direction It was confirmed by XMA that it was distributed substantially uniformly in the fiber cross section. As a result of evaluating the sunshine light resistance deterioration of this sample for 63 degrees * 300 hours, the residual strength was 13.2 kg and the maintenance rate was 41%. As a result of evaluating the carbon fade fade resistance deterioration of the same sample at 63 degrees for 300 hours, the remaining strength is 12.9k.
and the maintenance rate was 40%.

[0034]

Comparative Example 3 In the yarn making method shown in Example 1, the hydrated gel-forming inorganic material has a refractive index of about 2.5 and an average particle diameter of 0.5.
A hydrated gel containing 2% of anatase-type TiO2 was applied to the undrawn yarn after washing with water, dried and hot drawn, and the product was wound at 500 m / min to obtain a yarn of 1500 denier. The physical properties of this aramid fiber were as follows. Denier: 1503 Denier yarn Strength: 36.8 kg Strength: 24.5 g / d Elongation at break: 4.65% Modulus: 573 g / d TiO2 concentration in fiber: 0.34% The distribution of TiO2 in the fiber cross-section direction is It was confirmed by XMA that the surface layer was substantially within 5%. As a result of evaluating the sunshine light resistance deterioration of this sample for 63 degrees * 300 hours, the residual strength was 13.2 kg and the maintenance rate was 36%. The same sample was evaluated for carbon fade fade resistance deterioration of 63 degrees * 300 hours, and as a result, the residual strength was 13.6 kg and the maintenance rate was 37%.

[0035]

As described above, according to the present invention, it is possible to obtain an aramid fiber having excellent light resistance without deteriorating the physical properties of the fiber.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

[0033]

[Comparative Example 2] In the yarn making method shown in Example 2, the additive to the dope used was a silica having a refractive index of about 1.6 and an average particle diameter of 0.7μ was 2%, and the other conditions were the same. did. The physical properties of the obtained aramid fiber were as follows. Denier: 1503 denier yarn strong: 32.3Kg Strength: 21.5 g / d elongation at break 4.10% modulus: 523 g / d fibers in SiO ₂ concentration: 0.35% In addition, the SiO ₂ put in the fiber cross-sectional direction It was confirmed by XMA that the distribution was substantially uniform within the fiber cross section. As a result of evaluating the sunshine light resistance deterioration of this sample for 63 degrees * 300 hours, the residual strength was 13.2 kg and the maintenance rate was 41%. As a result of evaluating the carbon fade fade resistance deterioration of the same sample at 63 degrees for 300 hours, the remaining strength is 12.9k.
and the maintenance rate was 40%.

Claims (1)

[Claims] 1. A refractive index of 2. at least on the surface layer of the fiber.
Inorganic particles having an average particle size of 0 or more and 0.3 μ or less are contained in an amount of 0.1% or more and 5% or less of the fiber weight, the single yarn fineness is 0.5 denier or more and 50 denier or less, and the mechanical properties satisfy the following range. An aromatic polyamide fiber characterized by being. Strength: 18g / de or more Elongation: 3.5% or more Initial modulus: 450g / de or more