KR970010691B1 - A spinneret - Google Patents

Abstract

The main body(2) of the spinneret is made of metal with a high anti-corrosion property, at the vital point of the nozzle, L/D, a tantalum or an alloy of gold and platinum is fused to the nozzle main body. A pure tantalum or an alloy of gold and platinum is cut and is fused to the nozzle main body with nitrogen added, the vertical hole is opened thru the profile and is processed, cleaned up and placed in the substitution path, at the outlet of the nozzle a nitride layer is formed.

Description

Spinneret

1 is a cross-sectional view of the spinneret of the present invention

2 is a cross-sectional view of a conventional spinneret

(A) of Fig. 3 is a cross sectional view

(B) is the overall sectional view of planar spinnerets;

* Explanation of symbols for the main parts of the drawings

1: detention hall 2: detention body

3: acid-resistant metal fusion surface 4: conical capillary profile hole

5: capillary hole at the discharge portion of the spinning stock solution 6: inlet surface of the capillary hole

7: capillary profile inlet T: total thickness of the detention

L: length of capillary hole LP: length of conical capillary profile

LT: Fusion thickness of acid resistant metal D: Diameter of capillary hole

The present invention relates to spinnerets of polyparaphenylene terephthalamide-based synthetic fibers, that is, wholly aromatic polyamide long fibers, and more particularly, to spinnerets of pressure, corrosion resistance, and abrasion resistance, in particular sulfuric acid concentration of 97 to 100%. After dissolving a polyparaphenylene terephthalamide polymer in a concentrated sulfuric acid solution in a certain amount or more to form a spinning dope, the fiber properties are improved when spinning a wholly aromatic polyamide fiber in a filament.

will be.

Conventionally, as this kind of chemical fiber detention, precious metals, which are alloys of gold and platinum, having excellent corrosion resistance and processability, have been widely used. However, these materials are not only economically disadvantageous due to their high price, but also have low hardness of the material itself. Due to the poor mechanical properties, the shape is deformed due to the rising pressure during spinning, which makes it impossible to produce filamentary wholly aromatic polyamide long fibers effectively.

And spinnerets made of ordinary materials have a very rapid rate of corrosion due to sulfuric acid dope at the site of the orifice where filamentary long fibers are formed. The diameter of the capillary hole) is gradually out of specification, the fineness fluctuation and non-uniformity is generated, the long fiber is cut and the radioactivity is reduced, as well as the physical properties of the fiber is deteriorated.

In the production of wholly aromatic polyamide fibers, sulfuric acid is generally used as a suitable solvent and coagulant, and sulfuric acid is a highly corrosive solvent although there are differences in corrosiveness depending on concentration and temperature.

Accordingly, the present inventors have completed the present invention as a result of earnestly examining to improve the corrosion resistance of spinnerets and the physical properties of fibers.

Therefore, the present invention uses a metal having excellent corrosion resistance to sulfuric acid as a spinneret material and forms the shape of the hole into a conical capillary profile, thereby making it possible to manufacture filamentary wholly aromatic polyamide fibers having excellent physical properties at low cost. The purpose is to provide spinnerets.

Hereinafter, the present invention will be described in detail.

In the present invention, the detention body 2 is made of tungsten alloy steel, hastelloy steel sheet or stainless steel plate, and tantalum or alloy steel of platinum and gold is fused to the lower portion 3, and a conical capillary profile shape ( It relates to a spinneret characterized in that the detention hole of 4) is formed.

Hereinafter, the present invention will be described in more detail.

The present invention forms the detention body (2) with tungsten alloy steel, hastelloy steel sheet, stainless steel sheet as a metal with excellent corrosion resistance in sulfuric acid solvent, and increase the corrosion resistance and wear resistance to L / D which is the life of detention Tantalum or an alloy of gold and platinum is fused to the detention body in order to make it work.

After that, a cap hole is formed on the capillary hole and the conical capillary profile, followed by nitriding heat treatment in a nitrogen atmosphere. The nitriding heat treatment is performed to minimize the damage from the outside by increasing the hardness and improving the abrasion resistance of the capillary hole at the discharge portion of the spinning solution.

In detail, the nitriding heat treatment process is carried out by applying industrially pure tantalum (less than 3% by weight of tungsten) or an alloy plate of gold and platinum by adding nitrogen while cutting mechanically low but high corrosion resistance. After fusion and contact with the detention body, drill the detention hole vertically on the conical capillary profile, clean it, put it in the substitution furnace of nitrogen atmosphere, and perform general heat treatment to form the nitride layer on the exit surface of the detention.

The heating temperature and time are closely related to the thickness of the surface nitride layer of fused tantalum, and can be controlled according to the L / D and shape of the capillary hole.

When using an alloy of platinum and gold as the fusion metal, the corrosion resistance and hardness is excellent when the platinum content is 30 to 40% by weight.

High-strength wholly aromatic polyamide fibers have high tensile strength when spinning spinnerets have a small diameter and a large ratio of length to diameter (L / D) due to their hydrodynamic properties when spinning. .

Therefore, in the present invention, the diameter D of the capillary holes 5 is 0.03 to 0.1 mm, and the L / D is 2 or more.

In addition, in order to facilitate the flow and arrangement of the molecular chain within the mold and to increase the molecular chain orientation to improve the radioactivity and the tensile strength of the fiber, the capillary hole in the capillary profile (4) and the L / D of the capillary hole Make a hole.

In order to produce high strength and high elastic fibers, the molecular chains forming the fibers should be basically arranged in the stretching direction and the stress should be uniformly distributed in the molecular chains.

In addition, the wholly aromatic polyamide fibers forming the liquid crystal due to the rigidity of the high molecular weight are greatly affected by the size of the capillary hole and the shape of the capillary profile of the spinneret.

In conventional detention, the physical properties and the radioactivity of the fibers are lowered since the capillary profile is generally rounded hole (see FIG. 2) without forming the capillary profile at the front end where the L / D is formed.

One of the characteristics of the manufacturing process of the wholly aromatic polyamide fibers is due to the contact between the spinning solution and the coagulation bath, extraction of the solvent, and the long fibers have a core structure of inner structure and a skin layer of outer structure. It has a double structure of, and the excellent mechanical properties of the tensile strength and the initial modulus of elasticity is due to the skin layer structure in which rod-shaped polymer molecular chains are intertwined with each other.

On the other hand, in the core structure of the fiber, cylindrical crystals are regularly stacked in the fiber length direction, thereby deteriorating the mechanical properties of the fiber at this interface.

Therefore, in the present invention, the diameter D of the capillary holes 5 is 0.03 to 0.1 mm, L / D 2 or more, and the length LP of the conical capillary profile hole is 5 times or more of the capillary hole length L, and the capillary profile inlet. (7) by forming a detention hole with a diameter of 0.3 ~ 0.9mm by uniformly diffusing and desolventing the sulfuric acid solvent in the spinning stock solution in a coagulation bath to increase the range of the skin layer in the fiber cross-section to improve the mechanical properties of the fiber It is possible to continuously produce filamentary long fibers having excellent physical properties by facilitating the arrangement and flow of polymer molecular chains.

The thickness T of the whole mold must be able to withstand the pressure required for spinning, and is preferably 1.0 to 5.0 mm in order to maintain the minimum thickness that can penetrate the hole of the capillary profile.

If the thickness is too thin, it will not be able to withstand the minimum pressure of 75 kg / cm 2 during spinning, and if it is too thick, it will not be able to penetrate the hole of the capillary profile.

The material of the detention body 2 also affects the thickness T of the whole detention body. It is important to select the material with excellent mechanical strength and corrosion resistance, and also the processability of the spinneret hole. In consideration of these points, the body material of the detention should be made of hastalloy steel sheets, stainless steel sheets, tungsten alloy steel, or the like.

The fusion height (LT) of tantalum or alloy steel of platinum and gold is preferably 3 to 10 times the length (L) of the capillary hole, which is uniform so that the size and shape of the L / D and the capillary profile of the cap hole do not change from corrosion. This is to maintain the physical properties and spinning properties of the fiber.

If the fusion height is too thick, it is weak against internal pressure and too thin, and the corrosion of the capillary hole and the profile hole is concerned.

In the present invention, the detention can be made into a detention-type detention (Fig. 3 (A)) or a planar detention (B) (D).

Such spinneret of the present invention solves the problems caused by the corrosiveness, abrasion, and pressure rise of the spinning dope in spinning the wholly aromatic polyamide long fibers and at the same time continuously obtains fibers excellent in tensile strength and initial elastic modulus. There are advantages to it.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by the Examples.

(Example 1)

The polyparaphenylene terephthalamide polymer having an intrinsic viscosity of 6.5 was dissolved in 100% sulfuric acid to remove bubbles and foreign substances, and then the spinning stock solution was discharged into the spinneret. At this time, spinneret is fused to the detention body of Hastalloy-B with a tantalum of purity 99.2% by weight to a thickness five times the length of the capillary hole (L), and then subjected to heat treatment through the detention hole to a hardness (Hardness value) of 250. Reached.

The diameter of the capillary hole was 0.07mm, L / D was 2.0, LP and LT were 5 times of L to form a conical capillary profile. The diameter of the inlet was 0.5mm. The spinning stock solution was discharged and spun.

(Examples 2 and 3, Comparative Examples 1 to 8)

It was carried out in the same manner as in Example 1, except that the spinneret, the body material, the type of the fusion metal, and the spinneret having the LT changed as shown in Table 1 below were used.

The results of Examples 1 to 3 and Comparative Examples 1 to 8 are shown in Table 1 below.

TABLE 1

※ H-B: Hastalloy-B

W: Tungsten Alloy Steel

S-316: Stainless Steel SUS-316

Ta: tantalum

LT: Fusion thickness of acid resistant metal (mm), multiple for L

· Uniformity: The constant thickness of the fiber, the uniformity, and the rate of change of the fiber property is bad when it is defective

Corrosion Test Method: Temperature 40 ℃ × 100% Sulfuric Acid × Stirring

· Radioactivity: ① Application point: Test result after 1 year of detention.

② radioactive meaning:

(A: 1 hour radiation-winding success rate, B: 1 hour radiation-winding failure rate,

A + B≥10 times) evaluation standard

(Examples 4 and 5 and Comparative Examples 9 to 11)

The diameter of the capillary hole, L / D, LP, the diameter of the capillary profile was carried out in the same manner as in Example 1 using the spinneret changed as shown in Table 2, the results are shown in Table 2 below.

TABLE 2

※ LP: The length of the conical capillary profile, the multiple of the length of the capillary hole (L).

※ Other abbreviations and various evaluation criteria are the same as Table 1 above.

(Comparative Example 12)

As a result of using fused tantalum as a spinneret with a hardness of 170 HV without heat treatment under the same conditions as in Example 1, the L / D gradually decreased due to abrasion of the spinning dope, and the spinneret was heat-treated due to the damage of capillary holes. The life of detention is shorter by 70%. Over time (within 1 month), wear occurred in the L / D area of detention, and radioactivity was not good. At this time, the hardness of the fusion splice exit surface was about 100.

(Comparative Example 13)

Under the same conditions as in Example 1, the inlet surface of the capillary hole was made into a rounded hole (see FIG. 2) instead of making the capillary profile shape, and as a result, spinning was not good and the fiber property was 1g / d was lowered.

(Comparative Example 14)

In the same manner as in Example 1, a hardness of about 240 HV was produced in the same manner as in Example 1, and a warpage was generated due to the abrasion resistance and corrosion resistance of L / D. This caused and continuous spinning was impossible.

Claims (7)

The detention body 2 is made of tungsten alloy steel, hastelloy steel plate or stainless steel plate, and tantalum or alloy steel of platinum and gold is fused to the lower part 3, and a conical capillary profile image 4 Spinneret, characterized in that the detention hole and the capillary hole (5) is formed. The spinneret according to claim 1, wherein the thickness (T) of the whole cap is 1.0-5.0 mm. The spinneret according to claim 1, wherein the diameter (D) of the capillary hole (5) is 0.03 to 0.1 mm, and the ratio (L / D) of the capillary hole length (L) to the diameter is two or more. 2. The spinneret of claim 1, wherein the hole formation height LP of the conical capillary profile is at least five times the length of the capillary hole. The spinneret according to claim 1, wherein the fusion thickness LT of the fusion metal is 3 to 10 times the length L of the capillary hole. 2. The spinneret according to claim 1, characterized in that the diameter of the capillary profile inlet (7) is 0.3-0.9 mm. The spinneret according to claim 1, wherein the spinneret can withstand a radial pressure of 75 kg / cm 2 or more.