KR20160037256A

KR20160037256A - Method of coating carbon-fiber with sizing agent, apparatus thereof, and complex materials manufactured by the same

Info

Publication number: KR20160037256A
Application number: KR1020140128785A
Authority: KR
Inventors: 정희록; 최미영; 정성륜
Original assignee: 주식회사 효성
Priority date: 2014-09-26
Filing date: 2014-09-26
Publication date: 2016-04-06

Abstract

The present invention relates to a coating method of a carbon fiber sizing agent, an apparatus thereof, and a composite material manufactured by the same. More particularly, the present invention relates to a method for coating a sizing agent to carbon fiber, wherein solids sizing agent and carbon fiber contact each other. The coating method of the present invention has enhanced workability by increasing rate of fixing fabric width and allowing carbon fibers to have uniform width of tow. Also, the carbon fiber manufactured according to the present invention and the complex material comprising the same have enhanced physical properties.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a carbon fiber sizing agent application method, a carbon fiber sizing agent application method, and a composite material produced by the method.

The present invention relates to a method for applying a carbon fiber sizing agent, an apparatus therefor, and a composite material produced thereby.

Background Art [0002] As demand for high performance materials improved in physical properties in the fields of construction, automobiles and electronic materials has increased, research on composite materials having properties such as light weight, high strength and high elastic modulus has been actively conducted. It is carbon fiber that becomes. In other words, while various attempts have been made to use composite materials, one of such reinforcing materials has been rapidly expanding its applications as carbon fibers.

However, the conventional composite material is made of a thermosetting resin such as carbon fiber and an epoxy resin, an unsaturated polyester resin, a phenol resin, a diallyl phthalate resin, or a thermoplastic resin such as polyamide, polyolefin, polyacetal, polycarbonate, Is used as a matrix resin. Since carbon fibers have a small elongation, napping is easily caused by mechanical friction or the like, and there is a problem that wettability to the matrix resin is insufficient.

Therefore, usually, the surface of the carbon fiber is treated with a sizing agent for the purpose of strengthening the bonding between the carbon fiber used as the reinforcing material and the matrix resin.

Conventional techniques for sizing treatment of carbon fiber surfaces can be understood with reference to Patent Document 1 below. As a result, all of the contents of Patent Document 1 are quoted and incorporated as part of the prior art in the specification of the present invention.

Patent Document 1 discloses a carbon fiber-reinforced prepreg product which can impart excellent aggregate properties and widening property to carbon fibers. The prepreg product to which such carbon fibers are applied is a sizing agent for carbon fibers Based on 100 parts by weight of the epoxy resin, 2 to 25 parts by weight of an emulsifier; And 3 to 10 parts by weight of a curing agent.

As can be understood from Patent Document 1, conventionally, a sizing agent is attached in such a manner that carbon fiber washed and dried after surface treatment is immersed in a sizing agent solution.

In the case of the method of immersing the carbon fiber in the liquid sizing agent solution as in the prior art, the influence on the characteristics such as the drape or the width of the carbon fiber is greatly influenced by the chemical composition or the viscosity of the sizing agent. Furthermore, when composites are produced, they also affect the thickness after resin impregnation. This is further exacerbated by the surface tension between the liquid sizing agent and the carbon fibers.

The higher the molecular weight of the epoxy in the sizing agent, the more stable the shape of the carbon fiber tow. In this case, however, another problem is that the width of the carbon fiber tow becomes narrow due to the sizing agent having a high viscosity in the sizing agent drying process have.

KR publication 10-2009-0056896 A (2009.06.03.)

An object of the present invention is to improve the workability by changing the coating method of the liquid sizing agent into a solid form, lowering the surface tension generated between the sizing agent and the carbon fibers, And also to provide a method of applying a carbon fiber sizing agent which improves the physical properties of finally produced carbon fibers, an apparatus thereof, and a composite material produced thereby.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art,

A method of applying a sizing agent to a carbon fiber,

A method for applying a carbon fiber sizing agent characterized in that a solid sizing agent and carbon fibers contact each other.

The present invention also provides a method of applying a carbon fiber sizing agent, wherein the contact between the solid sizing agent and the carbon fiber is a press contact.

Further, in the present invention, there is provided a method of applying a carbon fiber sizing agent characterized in that the solid sizing agent and the carbon fiber are in contact by heating.

The present invention also provides a method of applying a carbon fiber sizing agent, wherein the contact between the solid sizing agent and the carbon fiber is a pressurizing and heating contact.

Also, in the present invention, the solid sizing agent is a film type or a powder type.

The present invention also provides a method of applying a carbon fiber sizing agent, wherein the contact between the solid sizing agent and the carbon fiber is a continuous contact between the solid sizing agent having the transport direction and the carbon fiber.

Further, the present invention provides a method for applying a carbon fiber sizing agent, wherein the direction of conveyance between the solid sizing agent and the carbon fibers is parallel or countercurrent.

Also, the present invention provides a method for applying a carbon fiber sizing agent, wherein the temperature of the heating contact is within a range of 50 to 300 占 폚.

The present invention also provides a method for applying a carbon fiber sizing agent, wherein the solid sizing agent has a room temperature viscosity of 1.0 × 10 ⁷ to 1.0 × 10 ⁹ cPs.

Further, as an apparatus for applying a sizing agent to carbon fibers,

A film supply unit including a supply roller for supplying and discharging the wound solid-sizing agent film, and a collection roller for collecting the collected solid-sizing agent film;

A carbon fiber supply portion including a carbon fiber winding roller winding the carbon fiber in a clockwise or counterclockwise direction;

A pressurizing roller for establishing a press contact between the solid sizing agent film and the carbon fiber, a heating plate for establishing heat contact between the solid sizing agent film and the carbon fiber, and a cooling plate for cooling the carbon fiber coated with the heated sizing agent Contact; And

And a guide portion including a guide roller for gripping the solid sizing agent film and the carbon fibers so as to be brought into contact with and transported from above and below.

Further, in the apparatus of the present invention, the feeding roller and the collecting roller are wound in the same or opposite direction as the take-up roller.

Also provided is a composite material comprising carbon fibers produced by the method of the present invention.

The present invention has the effect of improving the workability and, at the same time, improving the physical properties of the carbon fiber finally produced and the composite material containing the same, by increasing the sag width fixing ratio and having a uniform toe width.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing an embodiment of a sizing agent application device of the present invention. FIG.
2 is a view showing the contact between the solid sizing agent film of the present invention and the carbon fiber.

Hereinafter, the present invention will be described in detail.

According to an aspect of the present invention,

A method of applying a sizing agent to a carbon fiber, wherein the solid sizing agent and the carbon fiber contact each other.

When the sizing agent is applied, solid sizing agent coated on the film is supplied not by liquid phase impregnation with a sizing agent dispersed in an aqueous solution but by treating it with heat or pressure. The carbon fiber thus produced can be impregnated with a resin to produce a composite material having excellent physical properties from uniform thickness and excellent shape stability in the production of a composite material.

The solid sizing agent and the carbon fibers may be in contact, pressurized, and / or heated contact, and preferably are pressurized and heated contact. This is because the solid sizing agent may not be uniformly coated on the carbon fiber only by the contact by pressurization. In this case, the temperature of the heating contact is preferably within the range of 50 to 300 ° C, more preferably within the range of 100 to 200 ° C, and even more preferably within the range of 120 to 170 ° C. If the temperature is lower than 50 ° C, the solid sizing agent may not be uniformly melted to uniformly coat the carbon fiber. If the temperature is higher than 300 ° C, the solid sizing agent may become a complete liquid phase, Technology and the like.

The solid sizing agent may be solid, and is not particularly limited, but may be a film type or a powder type, and is more preferable because the film type is convenient in the process.

The composition of the solid sizing agent may be a conventional sizing agent well known to those skilled in the art (hereinafter referred to as " those skilled in the art "). However, even in this case, the viscosity at room temperature of the solid sizing agent should be within the range of 1.0 × 10 ⁷ to 1.0 × 10 ⁹ cPs. This is because the sizing agent can be smoothly applied to the surface of the carbon fiber without causing problems such as reduction in surface roughness due to the surface tension between the carbon fiber and the solid sizing agent at a room temperature viscosity within this range.

The contact between the solid sizing agent and the carbon fibers can be achieved by intermittent or continuous contact, but from the viewpoint of process efficiency, it is preferable to continuously contact the solid sizing agent having a constant transport direction and the carbon fibers Do.

In the case of the continuous contact, the direction of conveyance between the solid sizing agent and the carbon fibers is preferably such that the direction of conveyance of the solid sizing agent and the carbon fibers is the same in the direction of conveyance, or the conveying direction of the solid sizing agent and the carbon fibers is They may be countercurrent countercurrent directions. A person skilled in the art will be able to properly select one of the above-mentioned co-current direction and counter current direction in the transport direction in consideration of various process conditions.

Another aspect of the present invention is an apparatus for applying a sizing agent to carbon fibers.

FIG. 1 shows an exemplary embodiment of the coating apparatus of the present invention, and will be described on the basis of this embodiment.

In the apparatus for applying the sizing agent to the carbon fiber of the present invention,

A film supply section 3, a carbon fiber supply section 5, a contact section 7, and a guide section 9.

The film supply unit 3 includes a supply roller 10 which unwinds the film of the solid sizing agent which is wound in a counterclockwise direction to supply the film from left to right, And a collecting roller 12 for collecting the supplied film again.

The carbon fiber supply portion 5 includes a carbon fiber take-up roller 22 that winds the carbon fiber clockwise or counterclockwise. At this time, the carbon fibers 200 may be fed from the rollers on which the carbon fibers are wound, but may be transferred directly from the step of carbonizing the precursor fibers. The method of supplying the carbon fibers is not particularly limited. The feeding roller and the collecting roller may be wound in the same or opposite direction as the take-up roller. In the same direction, a cross-directional contact will occur between the solid sizing agent film and the carbon fiber, and in the opposite direction, an anti-directional contact will occur between the solid sizing agent film and the carbon fiber.

The contacting portion 7 comprises at least one pressure roller 30 for making a pressure contact between the solid sizing agent film and the carbon fibers, a heating plate 40 for making a heating contact between the solid sizing agent film and the carbon fibers, The sizing agent may be configured to include a cooling plate 50 for cooling the coated carbon fibers. At this time, the pressure roller 30 is positioned above and below the heating plate 40, respectively, so as to apply pressure and heat contact between the solid sizing agent film and the carbon fibers.

The guide portion 9 includes at least one pair of guide rollers for vertically holding the solid sizing agent film and the carbon fibers so as to be contacted and transferred.

The solid sizing agent film (100) is a film provided with a solid sizing agent on the release paper sheet. After passing through the contact portion (7), the solid sizing agent is applied to the carbon fiber, And the release paper is wound on the film recovery roller 12. Fig. 2 shows the contact between the solid sizing agent film and the carbon fiber.

According to another aspect of the present invention,

Is a composite material comprising carbon fibers produced by the method of the present invention.

Carbon fibers are widely used as reinforcing composite materials by mixing with resins, not by themselves as ordinary fibers. Here, the composite material means a resin composite composition (PMC) such as FRP (fiber reinforced plastics).

The carbon fiber produced by the method of the present invention has an effect of increasing the strength conversion ratio (composite strength / carbon fiber strength) of the properties of the carbon fiber, ultimately improving the strength of the composite material.

Hereinafter, the present invention will be described in more detail by way of examples. It is to be understood that the following embodiments are for the purpose of illustration only and are not intended to limit the scope of the present invention.

Example

Example One

98% by weight of acrylonitrile as a main component and 2% by weight of itaconic acid as an auxiliary component were added, and dimethylsulfoxide as a solvent was added thereto to introduce azobisisobutyronitrile as an initiator in an amount of 0.1% by weight based on the weight of the total monomer. Thio Glycol was injected in an amount of 0.2% by weight based on the weight of the total monomer to effect solution polymerization.

An acrylonitrile-based polymer dopant stock solution containing 20 wt% of a copolymer having an intrinsic viscosity of 2.0 was prepared. The dope stock solution was dried and wet-spinned with a gap of 5 mm in a coagulating bath composed of dimethyl sulfoxide and water using 6,000 nozzles, and an emulsion containing a silicone type emulsion, a modified epoxy emulsion and an ammonium compound was applied, dried and densified, And stretched under pressure steam to obtain precursor fibers for carbon fibers.

Using carbon fiber precursors, chlorinated flame retardants with specific gravity of 1.35 were produced in an oxidizing atmosphere and carbonized under nitrogen atmosphere at 300 to 500 ° C. The carbonized fiber was immersed in a surface treatment tank to perform electrolytic oxidation surface treatment, and a sizing agent was given as follows.

The sizing agent is composed mainly of an epoxy (bisphenol A type epoxy resin) compound and a resin mixed with a polyester compound. The sizing agent thus prepared had a room temperature viscosity of 2 x 10 < ⁸ > cPs and coated itself on the film without emulsification in water.

The sizing agent coated on the film is fed to the surface of the carbon fiber after the surface treatment is finished. The sizing film is heated and pressed at the same speed as the carbon fiber transporting speed, and the film is rewound to attach the sizing agent to the carbon fiber bundle. When the sizing film is supplied to the carbon fiber, the temperature is 140 ° C. The pressure applied to the carbon fiber is 0.4 kg / cm ² , the sizing agent on the film and the surface of the carbon fiber are integrated, and the film is rewound to remove from the carbon fiber And the surface is smoothed through a guide roll, and then wound by a winder.

The prepared carbon fibers were measured for physical properties such as haze, thickness and mechanical strength. The mechanical strength of the carbon fiber was measured by manufacturing strands. The carbon fiber strength was 5.5 GPa. In order to determine the physical properties of the composite carbon fiber, the ring burst strength was measured by filament winding using a hoop method, and the composite material strength conversion ratio (composite material tensile strength / carbon fiber tensile strength) was calculated.

As the matrix resin for the composite material, bisphenol A type epoxy resin, amine type curing agent and 2E4MZ type promoter were mixed and used. Ring burst test specimens were prepared as follows.

The carbon fiber was rewound on an aluminum mandrel having a diameter of 200 mm, a width of 100 mm, and a thickness of 5 mm, passed through a resin bath to impregnate the resin, passed through a guide and rotated four times on a mandrel. And the pre-cure was carried out. After the gelation was completed, curing was carried out in a hot air oven at 130 ° C for 3 hours. The ring-shaped specimen was cut to a width of 25 mm, and the ring burst strength was measured based on ASTM 2290-92, and the average ring burst strength was obtained by setting n = 7.

Example 2

Carbon fiber was prepared in the same manner as in Example 1 except that a sizing agent having a viscosity of 5.0 x 10 ⁷ cPs at room temperature was used as the sizing agent and the heat treatment temperature was set at 130 캜.

Example 3

Carbon fiber was prepared in the same manner as in Example 1 except that a sizing agent having a viscosity of 1.0 x 10 ⁷ cPs at room temperature was used as the sizing agent.

Example 4

Carbon fibers were prepared in the same manner as in Example 1 except that the sizing agent having a viscosity of 5.0 x 10 ⁶ cPs at room temperature was used and the heat treatment temperature was set at 110 ° C.

Comparative Example One

Carbon fiber was prepared in the same manner as in Example 1 except that the sizing agent having an epoxy resin as a main component and having a viscosity of 2.0 x ^{10 8} cPs at room temperature was diluted with water to prepare a sizing bath And the carbon fibers were impregnated with the sizing agent so that the amount of the sizing agent became 1.0% by mass, dried at 140 ° C, and wound up to obtain carbon fibers.

Comparative Example 2

A sizing agent was prepared and given in the same manner as in Comparative Example 1 except that the sizing agent was dried at 130 캜 using a sizing agent having a viscosity of 5.0 x ¹⁰ < ^{7 >} cPs at room temperature and then wound up to obtain carbon fibers.

The physical properties of Examples 1 to 4 and Comparative Examples 1 and 2 were as shown in Table 1 below.

As shown in Table 1, when the sizing agent was applied as in the case of the embodiment, the shape stability of the carbon fiber was high. That is, it was found that the flatness ratio was increased as the warp width was widened, and the warp width after resin impregnation did not change much as compared with that before resin impregnation, which is advantageous for improving the strength conversion ratio.

1: sizing agent dispensing device
3: Film supply part 5: Carbon fiber supply part
7: contact portion 9: guide portion
10: film feed roller 12:
20: Carbon fiber feed roller 22: Carbon fiber take-up roller
30: pressure roller
40: Heating plate 50: Cooling plate
60, 62, 64: guide rollers
100: solid sizing agent film 200: carbon fiber

Claims

A method of applying a sizing agent to a carbon fiber,
Wherein the solid sizing agent is in contact with the carbon fiber.

The method of claim 1, wherein the contact between the solid sizing agent and the carbon fibers is a press contact.

The method of claim 1, wherein the contact between the solid sizing agent and the carbon fibers is a thermal contact.

The method of claim 1, wherein the contact between the solid sizing agent and the carbon fibers is a pressurizing and heating contact.

The method of claim 1, wherein the solid sizing agent is film or powder.

The method of claim 1, wherein the contact between the solid sizing agent and the carbon fibers is by continuous contact between the solid sizing agent having the transport direction and the carbon fibers.

7. The method of claim 6, wherein the direction of transport between the solid sizing agent and the carbon fibers is in the cocurrent or countercurrent direction.

4. The method of claim 3, wherein the temperature of the heating contact is in the range of 50 to 300 占 폚.

The method of claim 1, wherein the solid sizing agent has a room temperature viscosity within a range of 1.0 × 10 ⁷ to 1.0 × 10 ⁹ cPs.

An apparatus for applying a sizing agent to carbon fibers,
A film supply unit including a supply roller for supplying and discharging the wound solid-sizing agent film, and a collection roller for collecting the collected solid-sizing agent film;
A carbon fiber supply portion including a carbon fiber winding roller winding the carbon fiber in a clockwise or counterclockwise direction;
A pressurizing roller for establishing a press contact between the solid sizing agent film and the carbon fiber, a heating plate for establishing heat contact between the solid sizing agent film and the carbon fiber, and a cooling plate for cooling the carbon fiber coated with the heated sizing agent Contact; And
And a guide portion including a guide roller for gripping the solid sizing agent film and the carbon fiber from above and below so as to be brought into contact with and transported from the carbon fiber sizing agent film and the carbon fiber sizing agent film.

11. The apparatus for applying a carbon fiber sizing agent according to claim 10, wherein the feeding roller and the collecting roller are wound in the same or opposite direction as the take-up roller.

A composite material comprising carbon fibers produced by the method of any one of claims 1 to 9.