KR101429381B1 - Process for preparing a carbon fiber precursor - Google Patents

Abstract

In the present invention, the adhesion between the single fibers in the dry densification step and the secondary drawing step is suppressed, the micro / macro void due to abrupt cooling is reduced, the quality of the precursor fibers becomes excellent, and the properties of the precursor fibers And to provide a method of manufacturing a carbon fiber precursor which can make the change smaller.
In the present invention, chilled water is sprayed to hot shoe ladle, so that the cold water bath is made into two or more stages to prevent rapid cooling, and a small amount of emulsion is added to the last stage of the cold water bath Which makes the emulsion more adhered and uniformly adhered to the carbon fiber precursor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon fiber precursor,

The present invention relates to a method for producing a carbon fiber precursor. More particularly, the present invention relates to a method for cooling a yarn by spraying cold water onto a hot-rolled gentle, cooling the yarn so that the cold water bath is made into two or more stages so that rapid cooling is not performed, To a process for producing a carbon fiber precursor that allows the emulsion to be better adhered and uniformly adhered.

When the fineness is increased and the warpage is reduced, the permeability of the solution in the yarn is deteriorated in the spinning process and the water is not easily washed, and it becomes difficult to uniformly transfer the heat to the inside of the yarn when the temperature is raised. As a result, there is a short-term adhesion, a deterioration in stretchability, and a difficulty in uniformly adhering the emulsion, resulting in mowing in the process, resulting in poor processability and inferior productivity and quality.

In order to improve this, it is necessary to use a multi-stage stretching method in the hot water (more than 70 ° C) process, (2) a washing process, a hot water drawing process and an emulsion application process, And (3) methods in which the yarn from the hot water drawing process is immersed in a cold water bath or chilled water is sprayed on the yarn to cool the yarn, pass through the nip roller, and then enter the oil bath.

[Patent Document 0001] Korean Patent Publication No. 1996-0004575 (Method of Manufacturing Precursor Fiber for Carbon Fiber Production, Feb. 23, 1996)

Accordingly, it is an object of the present invention to provide a method for producing a precursor fiber, which is capable of suppressing the adhesion between the monolayer fibers in the densification step and the second step, And to provide a method for producing a carbon fiber precursor capable of reducing changes in physical properties.

In the method for producing a carbon fiber precursor of the present invention, acrylonitrile as a main component, itaconic acid as an auxiliary component, and dimethyl sulfoxide as a solvent are introduced into a polymerization reactor, and azobisisobutyronitrile as an initiator and thioglycol After the injection, a homogeneous solution was prepared by stirring, and the polymerization was continued to prepare an acrylonitrile-based polymer doped stock solution. The resultant was dry-wet-spinned in a coagulation bath composed of dimethylsulfoxide and water, A method for producing a carbon fiber precursor by stretching, followed by treatment with an emulsion, and stretching by pressurized steam,

The hot water extruded from the hot water drawing step is immersed in a cold water bath or chilled water is sprayed to the hot water extruder to cool the yarn, the cold water bath is made into two or more stages, and a small amount of an emulsion is added to the last stage of the cold water bath, Is performed.

The method of producing a carbon fiber precursor according to the present invention suppresses adhesion (affixation) between monolayer in the densification step in the densification step and the second step of stretching, decreases the micro / macrovoids due to abrupt cooling and improves the quality of the precursor fiber, The change in physical properties of the precursor fibers with the passage of time is reduced.

Further, the emulsions are more uniformly adhered to each other to prevent adhesion between short fibers in the chlorination step, thereby preventing the affixation and surface defects of carbon fibers to obtain high strength / high-elasticity carbon fibers.

In addition, since precursor fibers are produced by reducing the width of yarn, there is an advantage in that the production amount per unit facility is increased and the cost is lowered.

Hereinafter, the present invention will be described in detail.

The carbon fiber precursor produced according to the present invention is obtained from an acrylonitrile-based polymer, and its main component is an acrylonitrile unit. The content of the acrylonitrile unit is 90% by weight or more, particularly 95 to 99% by weight based on the total acrylonitrile-based polymer. When the content of the acrylonitrile unit is too small, the strength of the carbon fiber obtained by the sintering process is lowered , The mechanical properties of the carbon fiber may be deteriorated.

The acrylonitrile-based polymer may contain one or more copolymerizable components (auxiliary components), if necessary. The content thereof is preferably less than 10% by weight, for example, 1 to 5% by weight, based on the total acrylonitrile-based polymer. Suitable examples of the auxiliary component include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, citraconic acid, maleic acid and the like, and itaconic acid is particularly preferably used.

According to the present invention, the auxiliary component and the main component are injected into the organic solvent in an amount of 15 to 25% by weight, and the initiator, for example, azobisisobutyronitrile is used in an amount of about 0.1 to 20% by weight based on the weight of the monomer (main component and auxiliary component) 1% by weight, and a polymerization initiator such as Thio Glycol is added in an amount of 0.1 to 1% by weight based on the weight of the total monomer.

As the organic solvent in the present invention, a conventional organic solvent capable of dissolving an acrylonitrile polymer such as dimethylsulfoxide, dimethylformamide or dimethylacetamide can be used, but dimethylsulfoxide, which is an organic solvent having no amide bond, It is most preferable to use it.

After the injection of all of the monomers, the solvent and the additive (initiator or degree of polymerization regulator) is completed, the solution is stirred to form a homogeneous solution. When the polymerization is further carried out, an acrylonitrile-based polymer doped stock solution containing 20% by weight of a copolymer having an intrinsic viscosity of 2.0 .

According to the present invention, the dope stock solution is transported to a decoction tank as required, defoaming is carried out, and then the product is spinned into a coagulating bath consisting of dimethyl sulfoxide and water using a nozzle in a dry and wet manner. The spun carbon fiber precursor, that is, the acrylonitrile-based fiber, is drawn in hot water at 60 ° C or higher and then subjected to a three-stage cooling bath.

That is, according to the present invention, in order to increase the fineness of the carbon fiber precursor and reduce the warpage, to prevent adhesion between the single yarns in the spinning process, and to adhere the emulsions uniformly, the Onsukuni shine from the hot water drawing process is immersed in a cold bath, The cold water is sprayed to the shrine to cool the yarn. The cold bath is made into two or more stages to prevent rapid cooling, and a small amount of the emulsion is added to the last stage of the cold bath to make the process pre-Oiling Allowing the emulsion to be better adhered and evenly adhered.

Here, it is preferable to add an emulsion so that the temperature of the first step of the cold water bath is about 60 to 80 ° C, the temperature of the second step is about 50 to 70 ° C, the temperature of the third step is about 40 to 60 ° C, Do.

Thereafter, an emulsion containing a silicone type emulsion, a modified epoxy emulsion and an ammonium compound is added in an amount of 0.1 to 5.0% by weight and dried and densified by using a heating roller and stretched under a high-temperature pressurized steam to obtain a carbon fiber precursor fiber according to the present invention Can be obtained.

The total draw ratio of the prepared precursor fibers is generally 7 to 25 times, and the single fiber fineness is 0.5 to 2.0 dtex. The spun carbon fiber precursor is subjected to a chlorination treatment in an oxygen atmosphere and at a temperature of 200 to 400 占 폚 in an ordinary atmosphere and then carbonized at 800 to 2000 占 폚 in an inert atmosphere to obtain a carbon fiber precursor having uniform physical properties, Carbon fiber can be produced. The carbon fiber produced using the precursor of the present invention can be usefully used as a material for forming an energy-related substrate such as a CNG tank, a blade for a wind power generator, a turbine blade, and a structural reinforcement material for roads and bridges.

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

Example 1 to  2( Comparative Example 1 to  2)

Acrylonitrile as a main component, itaconic acid as an auxiliary component, and dimethyl sulfoxide as a solvent were injected into the polymerization reactor preferentially. At this time, the polymerization composition was 98% by weight of acrylonitrile and 2% by weight of itaconic acid, and the solvent was added so that the concentration of the monomer (main component and auxiliary component) was 22.0% by weight based on the total injection amount. Nitrile was added so as to be 0.1 wt% of the total monomer, and Thio Glycol, which is a polymerization degree regulator, was injected so as to be 0.2 wt% of the total monomer.

After injection of all monomers, solvents, additives (initiator and degree of polymerization regulator) was completed within 2 hours, the solution was stirred to prepare a homogeneous solution. Polymerization was carried out at 65 캜 for 14 hours to prepare an acrylonitrile-based polymer dopant stock solution containing 20% by weight of a copolymer having an intrinsic viscosity of 2.0.

The dope stock solution was stored at 50 ° C and the fibers were solidified by dry-wet spinning with a gap of 5 mm in a coagulating bath consisting of dimethyl sulfoxide and water using a nozzle having a diameter of 0.12 mm and a number of holes of 4000. The resultant coagulum was washed with water, extended to hot water of 60 ° C or more, and subjected to a 3-step cold water bath (70 ° C for 1 stage, 60 ° C for 2 stages, 50 ° C for 3 stages, and no cold bath in Comparative Example 2). As shown in the following Table 1, the emulsion concentration in the third stage was 0.8% in Example 1 and 3.0% in Example 2, and the emulsions were not added in Comparative Examples 1 and 2.

Thereafter, an emulsion containing a silicone type emulsion, a modified epoxy emulsion, and an ammonium compound was applied, dried and densified using a heating roller at 150 DEG C, and stretched under a high-temperature pressurized steam to obtain a precursor fiber for carbon fibers. The haze of thermal investigation was measured as shown in the following Table 1 and the affix of the precursor fiber for carbon fiber was evaluated. The difference in tensile strength CV% immediately after the production of the carbon fiber precursor fibers and after 60 days was evaluated and is shown in Table 1 below.

The carbon fiber precursor was used to shrink 10% at a temperature of 240 to 250 占 폚 while making a salt-resistant phosphor having a fiber specific gravity of 1.35, extended 3% under a nitrogen atmosphere at 300 to 500 占 폚 and shrunk 5% under a nitrogen atmosphere at 1350 占 폚, Fiber was obtained. The adherence of the chlorinated lacquer was evaluated and the strength of the carbon fiber strand was measured.

Although the preferred embodiments of the present invention have been described in detail to some extent, it is natural that various modifications can be made to them. It is therefore to be understood that the invention may be practiced otherwise than as specifically described herein without departing from the scope and spirit of the invention.

Claims (2)

Acrylonitrile as a main component, itaconic acid as an auxiliary component and dimethylsulfoxide as a solvent are injected into a polymerization reactor, and azobisisobutyronitrile as an initiator and thioglycol as a polymerization degree regulator are injected, and then a homogeneous solution is prepared by stirring , Polymerization was continued to prepare an acrylonitrile-based polymer doped raw solution, and then dried and wet-spinned in a coagulating bath composed of dimethylsulfoxide and water, and the coagulated carbon fibers spun out were heated in hot water, treated with an emulsion, A method of producing a carbon fiber precursor by stretching the carbon fiber precursor,
The hot water extruded from the hot water drawing step is immersed in a cold water bath or chilled water is sprayed to the hot water extruder to cool the yarn, the cold water bath is made into two or more stages, and a small amount of an emulsion is added to the last stage of the cold water bath, Wherein the carbon fiber precursor is a carbon fiber precursor. The method according to claim 1, wherein the cold water bath has a first stage temperature of 60 to 80 占 폚, a second stage temperature of 50 to 70 占 폚, a third stage temperature of 40 to 60 占 폚, and an emulsion having a concentration of 1% By weight based on the total weight of the carbon fiber precursor.