KR20160116697A - Preparation Method of Carbon Fiber Web for Polymer Composites - Google Patents

Abstract

The present invention relates to a method for manufacturing a carbon fiber web, with improved mechanical properties by treating a water-dispersed solution with ozone and improving dispersion, wherein a carbon fiber and a hydrophilic fiber are dispersed in the water-dispersed solution.

Description

Preparation Method of Carbon Fiber Web for Polymer Composites [

The present invention relates to a method for producing a carbon fiber web in which mechanical properties are improved by treating ozone with an aqueous dispersion in which hydrophilic fibers are dispersed together with carbon fibers to improve dispersibility.

In the conventional carbon paper manufacturing method, when carbon paper is produced by a wet-laid process, the carbon fiber is first dispersed in an aqueous solution or the like, dehydrated and ground through a wet paper forming apparatus, Carbon fiber web. The produced carbon fiber web is impregnated with a thermosetting resin or the like and then cured by applying heat and pressure. When a carbon sheet is formed through such a curing process, if the thermosetting resin in the finally formed sheet is manufactured by degreasing and high- Is completed. Such a method for producing carbon paper by a wet process is disclosed in Korean Patent Registration No. 10-1468866.

However, the carbon paper produced by such a wet process exhibits the property that the carbon fibers constituting the carbon paper are not uniformly dispersed to each other, resulting in a decrease in electrical conductivity and gas permeability of the carbon paper produced.

As another example, Korean Patent Registration No. 10-1392232 discloses a carbon paper dispersion method using a carbon fiber dispersion containing a carbon fiber whose surface has been oxidized by ozone treatment. The carbon fiber dispersion is prepared by mixing carbon fiber and carboxymethyl cellulose, polyethylene Discloses a method for producing carbon fibers by using a carbon fiber dispersion containing a thickener selected from the group consisting of titanium oxide, polyethylene glycol, hydroxyethyl cellulose, acrylic thickener, and mixtures thereof.

Korean Patent Registration No. 10-1468866 Korean Patent Registration No. 10-1392232

Accordingly, it is an object of the present invention to improve the mechanical properties of the resultant carbon fiber web by controlling the dispersibility of the carbon fiber as a constituent material of the carbon fiber web to uniformly disperse the carbon fibers in the produced carbon fiber web. The present invention also provides a method for manufacturing a carbon fiber web.

In order to achieve the above object,

Applying ozone to a dispersion in which carbon fibers are dispersed in water;

Adding and mixing polyvinyl alcohol fibers to the dispersion; And

Preparing a carbon fiber web by dewatering, papermaking and drying the dispersion to which the polyvinyl alcohol fiber is added through a wet paper forming apparatus

And a carbon fiber web.

According to the present invention, a carbon fiber web having excellent electrical conductivity and mechanical properties can be provided by ozone treatment and uniform dispersion of carbon fibers by polyvinyl alcohol fibers.

1 is a photograph of a wet-laid paper forming equipment used to produce the carbon fiber web of the present invention.
Fig. 2 is a photograph of carbon fiber webs of Examples 1 to 3 and Comparative Example 1 of the present invention. Fig.

In the present invention, a method for producing a carbon fiber web is disclosed in which ozone is treated with an aqueous dispersion in which polyvinyl alcohol fibers as hydrophilic fibers are dispersed together with carbon fibers to improve dispersibility and physical properties.

Each step will be described in detail below.

First, ozone is applied to a dispersion in which carbon fibers are dispersed in water.

The carbon fibers in the dispersion may have a length of 3.0 mm to 8.0 mm. When the length of the carbon fiber is less than 3.0 mm, the dispersibility is improved, but the porosity and the electrical conductivity are poor. On the other hand, when the length exceeds 8.0 mm, the carbon fiber is not well dispersed in the dispersion, It is not preferable.

The carbon fibers may be contained in an amount of 0.02 wt% to 0.5 wt% in the dispersion in consideration of the formation and the dispersibility of the carbon fiber web.

At this time, the ozone is preferably applied at 200 to 300 mg per hour. This ozone treatment can improve the dispersibility of carbon fibers.

Next, polyvinyl alcohol fiber is added to the dispersion and mixed.

When polyvinyl alcohol fibers are added to the dispersion, they are uniformly dispersed uniformly due to the entangle between fibers as a hydrophilic fiber, and the nonwoven fabric (web) improves the formability. At this time, the polyvinyl alcohol fiber is contained in an amount of 3 to 10% by weight in the dispersion. If the content of the polyvinyl alcohol fiber is less than the above range, the effect of improving the dispersibility is insignificant. On the contrary, if the content exceeds the above range, there is a problem of deterioration of the physical properties of the composite material produced using the carbon fiber web.

The dispersion is then dewatered, papermaking and dried through a wet paper forming apparatus to produce a carbon fiber web.

Since such a wet paper forming method is well known in the art, a detailed description thereof will be omitted herein.

The carbon fiber web produced according to the method of the present invention described above can produce a carbon fiber web having excellent mechanical properties because carbon fibers are uniformly dispersed in a dispersion and formed due to entanglement between polyvinyl alcohol fibers.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to assist the understanding of the present invention and should not be construed as limiting the scope of the present invention.

Example 1

). 성형된 탄소섬유 웹을 그물망건조기(Net dryer)와 습식부직포 건조기에 연결시켜 건조시켜 탄소섬유 웹을 제조하였다(dryer 온도 : 80℃, 평량×밸트폭×밸트속도 = 농도×pump속도, 40g/

×0.3m×2.0m/min = 0.4g/L×60L/min). 이렇게 제조한 탄소섬유 웹의 양쪽 면을 폴리프로필렌 필름(120 마이크로 두께)으로 200 ℃에서 2.5MPa로 30분간 합지하여 복합소재를 제조하였다.
The wet-laid equipment of FIG. 1 was used for carbon fiber web fabrication. 40 L of water and 388 g of 3 mm carbon fiber were put into a pulper, and 200-300 mg of ozone was added to water per hour, and the mixture was stirred for 1 hour. Then, 12 g of polyvinyl alcohol fiber was added and dispersed by stirring for 20 minutes. The dispersion containing polyvinyl alcohol and carbon fiber dispersed in a water tank was charged to 1000 L and mixed for 10 minutes. The dispersion was formed into a carbon fiber web on a Teflon coated belt using a wet-laid paper forming machine (Belt drive speed: 2.0 m / min, basis weight: 40 g /

). The formed carbon fiber web was connected to a net dryer and a wet nonwoven dryer to be dried to prepare a carbon fiber web (dryer temperature: 80 캜, basis weight × belt width × belt speed = concentration × pump speed, 40 g /

× 0.3 m × 2.0 m / min = 0.4 g / L × 60 L / min). Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Example 2

A carbon fiber web was prepared in the same manner as in Example 1 except that 380 g of carbon fibers and 20 g of polyvinyl alcohol fibers were used in Example 1. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Example 3

A carbon fiber web was prepared in the same manner as in Example 1 except that 380 g of carbon fibers and 20 g of polyvinyl alcohol fibers were used in Example 1. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Example 3

A carbon fiber web was prepared in the same manner as in Example 1 except that 360 g of carbon fibers and 40 g of polyvinyl alcohol fibers were used in Example 1. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Comparative Example 1

A carbon fiber web was prepared in the same manner as in Example 1 except that 400 g of carbon fiber was used and polyvinyl alcohol fiber was not used. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Comparative Example 2

A carbon fiber web was prepared in the same manner as in Example 3 except that polyvinylpyrrolidone was used in the same amount as in Example 3 instead of polyvinyl alcohol fiber. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Comparative Example 3

A carbon fiber web was produced in the same manner as in Example 3, except that PEG-PPG-PEG (molecular weight: 2700) was used in the same amount as in Example 3 instead of polyvinyl alcohol fiber. Both sides of the carbon fiber web thus prepared were laminated with a polypropylene film (120 micrometers) at 200 DEG C and 2.5 MPa for 30 minutes to prepare a composite material.

Experimental Example 1: Measurement of mechanical properties

(1) Tensile strength

The specimens were manufactured according to the Standard Test Method for Tensile Properties of Plastics (ASTM D638-08) and then measured using a Universal Test Machine (UTM). Five samples were taken and taken as an average value.

(2) Tensile modulus

The specimens were manufactured according to the Standard Test Method for Tensile Properties of Plastics (ASTM D638-08) and then measured using a Universal Test Machine (UTM). Five samples were taken and taken as an average value.

(3) Flexural strength

The test specimens were manufactured using Universal Test Machine (UTM) after standard specimens were manufactured using the Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials (ASTM D790-07). Five samples were taken and taken as an average value.

(4) Flexural modulus

The test specimens were manufactured using Universal Test Machine (UTM) after standard specimens were manufactured using the Standard Test Method for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials (ASTM D790-07). Five samples were taken and taken as an average value.

(5) Impact strength

Standard Test Method for Determining the Izod Pendulum After preparing specimens according to the Impact Resistance of Plastics (ASTM D256-06) standard, the Izod strength is measured using an impact strength meter. Five samples were taken and taken as an average value.

(6) Electrical resistance

A 5 cm x 5 cm sample was prepared and the surface resistance was measured using a four-terminal method. The sample was taken as an average value by measuring 10 portions.

division  Example 1  Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile Strength (Mpa) 148 152 158 143 140 138 Tensile modulus (GPa) 6.0 6.8 7.1 5.9 6.1 5.9 Flexural Strength (MPa) 310 314 315 313 314 308 Flexural modulus (GPa) 16 17 18 16 14 15.1 Impact strength (KJ / m ² ) 45.1 47.7 52.8 40.6 39.2 41.0 Electrical Resistance (Ω) 380 345 320 450 400 415

Claims (4)

Applying ozone to a dispersion in which carbon fibers are dispersed in water;
Adding and mixing polyvinyl alcohol fibers to the dispersion; And
Preparing a carbon fiber web by dewatering, papermaking and drying the dispersion to which the polyvinyl alcohol fiber has been added through a wet paper forming apparatus
Wherein the carbon fiber web is made of carbon fibers. The method according to claim 1, wherein the carbon fiber in the dispersion is contained in an amount of 0.02 wt% to 0.5 wt%. The method according to claim 1, wherein the polyvinyl alcohol fiber in the dispersion is contained in an amount of 3 to 10% by weight. The method of claim 1, wherein the ozone is applied at a rate of 200 to 300 mg per hour.

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