KR102519457B1 - Aramid fiber comprising cyano group - Google Patents

Abstract

The aramid fiber containing a cyano group according to the present invention is composed of an aramid copolymer containing an aromatic group substituted with a cyano group and has a two-layer cross-sectional structure consisting of a core layer (C) and a skin layer (S), and the skin It is characterized in that the thickness of the layer (S) is 100 to 400 nm.
Since the thickness of the skin layer constituting the skin-core structure of the aramid fiber containing the cyano group of the present invention maintains an appropriate level, a phenomenon in which a portion of the surface of the aramid fiber is removed due to friction with a guide during post-processing such as weaving can be effectively prevented, and it is useful as a yarn for rubber reinforcement due to its high elongation.

Description

Aramid fiber comprising cyano group {Aramid fiber comprising cyano group}

The present invention relates to an aramid fiber containing a cyano group (-CN), and specifically, the thickness of the skin layer constituting the skin-core structure is maintained at an appropriate level to minimize the generation of white powder in post-processing processes such as weaving, At the same time, it relates to an aramid fiber containing a cyano group having high elongation properties.

Hereinafter, the term "white powder phenomenon" refers to a phenomenon in which a portion of the surface of the aramid yarn comes off due to friction with a guide during a post-processing process such as weaving, and a fluff-ball is generated.

An aramid fiber containing an aromatic group in which a cyano group (-CN) is substituted (hereinafter abbreviated as "aramid fiber containing a cyano group") is usually as shown in FIG. 1 (i) aramid spinning dope (Dope) A process of spinning through a spinneret 20, (ii) a process of coagulating while sequentially passing the spun aramid fibers into a coagulation bath 30 and a coagulation tube 40 into which a coagulation solution is sprayed, (iii) coagulation A process of washing and neutralizing the aramid fibers while passing them sequentially over at least one washing roller 50 and, if necessary, the neutralizing roller 60, and (iv) drying the washed and neutralized aramid fibers with a drying device 70 It is manufactured by sequentially going through the winding process on the winding roller 80.

At this time, as an example of a method for producing an aramid spinning dope, as disclosed in Korean Patent Registration No. 10-171994, para-phenylenediamine and cyano-para-phenylene diamine are dissolved in an organic solvent or cyano Terephthaloyldichloride was added to and reacted with an organic solvent in which -para-phenylenediamine was dissolved alone to prepare a spinning dope containing a copolymerized aramid polymer containing an aromatic group in which a cyano group (-CN) was substituted. In this case, there is an advantage in that it can be prepared as a spinning dope without a process of dissolving the copolymerized aramid polymer in sulfuric acid.

The aramid fiber containing a conventional cyano group (-CN) prepared by the above method has a two-layer cross-sectional structure consisting of a core layer (C) and a skin layer (S) as shown in FIG. 2, but the skin Since the thickness of the layer (S) is too thick, the elongation of the fibers is reduced, and a problem occurs in that fluff-balls are severely generated due to friction with a guide in a post-processing process such as weaving.

An object of the present invention is to effectively prevent the occurrence of white powder, in which a portion of the surface of aramid fibers falls off due to friction with a guide during a post-processing process such as weaving, to have excellent post-processability and high elongation, so that it is useful as a yarn for reinforcing rubber, etc. It is to provide an aramid fiber containing a cyano group.

In order to achieve such a problem, in the present invention, when manufacturing an aramid fiber containing a cyano group having a two-layer cross-sectional structure consisting of a core layer (C) and a skin layer (S), the thickness of the skin layer (S) 100 to 400 nm, preferably 100 to 250 nm.

Since the thickness of the skin layer constituting the skin-core structure of the aramid fiber containing the cyano group of the present invention maintains an appropriate level, a phenomenon in which a portion of the surface of the aramid fiber is removed due to friction with a guide during post-processing such as weaving can be effectively prevented, and it is useful as a yarn for rubber reinforcement because it has high elongation.

1 is a schematic diagram of a process for producing an aramid fiber containing a cyano group.
Figure 2 is a schematic cross-sectional view of aramid fibers containing a cyano group.
Figure 3 is an atomic force microscope (AFM) height image (Height Image) photograph.
Figure 4 is a FD (Force Distance) image (Image) picture.
5 is a height image picture onto which a force distance (FD) image is projected.
Figure 6 is a photograph of a guide circular line drawn on the height image (Height Image) photograph of Figure 5;
Figure 7 is a height image (Height Image) photograph of the radiation passing through the center point.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The aramid fiber containing a cyano group (-CN) according to the present invention is composed of an aramid copolymer containing an aromatic group substituted with a cyano group and has a two-layer cross-sectional structure consisting of a core layer (C) and a skin layer (S) And, it is characterized in that the thickness of the skin layer (S) is 100 ~ 400㎚.

The aramid copolymer including an aromatic group in which the cyano group (-CN) is substituted has a repeating unit of the following general formula (I).

[In the formula (I), Ar is an aromatic group of the following general formula (II), and A is an aromatic group of the following general formula (III) or an aromatic group of the following general formula (II) and an aromatic group of the general formula (III) It is an aromatic group with a ratio of 1:9 to 9:1]

The skin layer (S) has a thickness of 100 to 400 nm, more preferably 100 to 250 nm.

When the thickness of the skin layer (S) exceeds the above range, the skin layer (S) becomes too thick, resulting in a serious white powder generation phenomenon during post-processing processes such as weaving, resulting in poor workability and lowering the elongation of the fiber to less than 4%. , If it is lower than the above range, fiber properties such as strength are too low, which is not preferable.

Looking at the method of measuring the thickness of the skin layer (S) in the present invention, a sample (aramid fiber containing a cyano group) is impregnated in an epoxy resin and then cured at 80 ° C. for 2 hours while being fixed vertically to the ground, EM-TXP (Target Surfacing System: model name) and ion milling device (Ion-miller) are used in turn to mill the roughness to a level of several nanometers, and then, using an atomic force microscope (AFM), the skin The thickness of layer (S) was measured. As an atomic force microscope (AFM), an NX-10 model from Park systems was used, and a diamond probe for nanoindentation was used.

Specifically, first, a height image is analyzed as shown in FIG. 3 using an atomic force microscope (AFM). Next, an atomic force microscope (AFM) is used to analyze a force distance (FD) image as shown in FIG. 4 .

In FIG. 4, the yellow area is the epoxy resin, the brown area is the skin layer (S), and the black area is the core layer (C).

Next, the FD image of FIG. 4 is projected onto the height image of FIG. 3 to obtain a height image as shown in FIG. 5 . Next, on the height image of FIG. 5 where the FD image is projected, a circular guide line is drawn as shown in FIG. 6 to create a center line on its own, and then passes through the center point as shown in FIG. It forms radiation that

Next, hardness is measured at a plurality of points located on the radiation along the radiation direction shown in FIG. 2 using an atomic force microscope (AFM).

Specifically, in the present invention, as a result of measuring the hardness at a measurement distance interval of 1 pixel (11.7 nm) along the radiation direction of FIG. The first measurement point with a hardness of 10% or less when measured three times in succession is the starting point of the skin layer, and the first measurement point with a hardness of less than 60% when a hardness lower than 60% or less than the hardness at the yarn center is measured three times in succession. With the measurement point as the last point of the skin layer, the distance from the start point of the skin layer to the last point of the skin layer is defined as the thickness of the skin layer.

The thickness of the skin layer in each of the 10 FD images of FIG. 4 obtained from the 10 samples (filaments) was measured at 8 sites along the 8 radiations generated at an angle of 45 ° from the yarn center as shown in FIG. Therefore, a total of 80 measured thickness values of the skin layer were obtained, and the average value thereof was obtained as the thickness of the skin layer (S).

When analyzing the thickness of the skin layer (S), data is analyzed after dividing by 265 pixels × 265 pixels for a sample range of 3 μm × 3 μm in size.

One pixel has 11.7 nm.

Next, look at an example of implementation of the methods for producing an aramid fiber containing a cyano group according to the present invention.

First, the present invention performs a step of preparing a spinning dope for producing aramid fibers. Specifically, after preparing a polymerization solvent by adding an inorganic salt to an organic solvent, para-phenylenediamine and cyano-para-phenylenediamine are dissolved together in the organic solvent or cyano-para-phenylenediamine alone After dissolving to prepare a mixed solution, primary polymerization is performed by adding a small amount of terephthaloyldichloride to the mixed solution while stirring the mixed solution to form a prepolymer in the polymerization solvent.

Subsequently, secondary polymerization is performed by additionally adding terephthaloyldichloride to the polymerization solvent to obtain a spinning dope for aramid production in which a copolymer of aramid copolymer containing an aromatic group substituted with a cyano group (-CN) is dissolved in an organic solvent. manufacture

At this time, the organic solvent is N-methyl-2-pyrrolidone (NMP), N, N'-dimethylacetamide (DMAc), hexamethylphosphoramide (HMPA), N, N, N', N' -Tetramethyl urea (TMU), N, N-dimethylformamide (DMF) or mixtures thereof may be used. As the inorganic salt, CaCl 2 , LiCl, NaCl, KCl, LiBr, KBr, or a mixture thereof may be used.

Next, as shown in FIG. 1, after spinning the prepared spinning dope through the spinneret 20, the spun aramid fibers are spun into the coagulation bath 30 and the coagulation solution is sprayed. After passing through the coagulation tube 40 in turn, the coagulated aramid fibers are washed with water while passing them sequentially over the washing roller 50 and the neutralizing roller 60, and then dried with the drying device 70 and wound on the take-up roller 80 Taken to prepare an aramid fiber containing a cyano group.

At this time, in an embodiment of the present invention, the spinning speed, the temperature of the coagulation solution, the distance from the direct bottom of the spinneret to the coagulation bath (hereinafter referred to as "air gap"), and the diameter of the spinneret hole, etc. are appropriately adjusted. Skin of aramid fiber The thickness of the layer (S) is adjusted to 100 to 400 nm, preferably 100 to 250 nm.

As an example of implementation, the spinning speed is adjusted to 100 to 400 m/min, the temperature of the coagulating solution is adjusted to 5 to 40 ° C, the length of the air gap is adjusted to 5 to 30 mm, and the diameter of the spinneret is 50 to 100 μm. Adjust with

When the spinning speed is higher than the above range, the thickness of the skin layer (S) becomes too thick, and when the temperature of the coagulating solution is too high above the above range, the thickness of the skin layer (S) becomes too thin, and the length of the air gap is When the thickness of the skin layer (S) is longer than the range, the thickness of the skin layer (S) becomes too thin, and when the diameter of the cap hole is smaller than the above range, the thickness of the skin layer (S) may be too thick.

Hereinafter, the present invention will be looked at in more detail through Examples and Comparative Examples.

However, the following implementation is only a preferred embodiment of the present invention, and should not be construed as limiting the protection scope of the present invention.

Example 1

An N-methyl-2-pyrrolidone (NMP) organic solvent containing 3% by weight of CaCl ₂ was placed in a reactor under a nitrogen atmosphere, and 50 mol% of p-phenylenediamine and cyano-para- A mixed solution was prepared by dissolving 50 mol% of phenylenediamine (cyano-p-phenylenediamine) in the reactor.

Subsequently, 100 mol% of terephthaloyl dichloride was added to the reactor containing the mixed solution to prepare a spinning dope containing a copolymerized aramid polymer.

Subsequently, as shown in FIG. 1, the spinning dope is spun through the spinneret 20, and then the spun aramid fibers are placed in a coagulation bath 30 containing water (coagulant solution) and water (coagulant solution). After passing through the sprayed coagulation tube 40 and coagulating it, the aramid fibers that subsequently passed through the coagulation tube 40 are washed and neutralized with water while passing through the drying roller 50 and the neutralization roller 60 in turn, and then the drying device After drying with (70), it was wound on a winding roller (80) to prepare an aramid fiber containing a cyano group.

At this time, the spinning speed was 100 m / min, the temperature of the coagulating solution was 40 ° C, the length of the air gap was 27 mm, and the diameter of the cap hole was 90 μm.

The results of measuring the thickness of the skin layer of the prepared aramid fibers were shown in Table 1.

Example 2~ Example 4 and Comparative Example 1 to Comparative Example 2

Aramid fibers were prepared in the same manner as in Example 1, except that the spinning speed, the temperature of the coagulating solution, the length of the air gap, and the diameter of the cap hole were changed as shown in Table 1.

The results of measuring the thickness of the skin layer of the prepared aramid fibers were shown in Table 1.

division
manufacturing condition skin layer thickness
(nm) spinning speed
(m/min) coagulant temperature
(℃) air gap length
(mm) Detention hole diameter
(μm) Example 1 100 40 27 95 110 Example 2 180 31 20 82 180 Example 3 275 17 12 68 290 Example 4 390 6 5 52 385 Comparative Example 1 480 One 2 44 460 Comparative Example 2 50 46 35 110 75

10: extruder 20: spinneret
30: coagulation tank 40: coagulation tube
41: coagulant nozzle Y: aramid fiber
50: water roller 60: neutral roller
70: drying device 80: winding roller
S: skin layer C: core layer

Claims (3)

After spinning the spinning dope in which the aramid copolymer containing the cyano group-substituted aromatic group is dissolved through a spinneret, the spun aramid fibers are sequentially passed through the coagulation bath and the coagulation tube into which the coagulation solution is sprayed, and then the coagulated aramid The fiber is washed with water while passing through the washing roller and the neutralizing roller in turn, dried with a drying device, and then wound around a take-up roller to produce an aramid fiber having a two-layer cross-sectional structure consisting of a core layer (C) and a skin layer (S) in how to do it,
Adjust the spinning speed to 100~400m/min, the temperature of the coagulating solution to 5~40℃, the length of the air gap to 5~30mm, and the diameter of the spinneret hole to be adjusted to 50~100㎛. Method for producing aramid fibers containing a cyano group, characterized in that for adjusting the thickness of the skin layer (S) to 100 ~ 400㎚. The method of claim 1, wherein the skin layer (S) has a thickness of 100 to 250 nm. The method of claim 1, wherein the aramid copolymer containing an aromatic group in which the -CN group is substituted has a repeating unit of the following general formula (I).

[In the formula (I), Ar is an aromatic group of the following general formula (II), and A is an aromatic group of the following general formula (III) or an aromatic group of the following general formula (II) and an aromatic group of the general formula (III) It is an aromatic group with a ratio of 1:9 to 9:1]

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