KR101159932B1 - A method of preparing thermoplastic prepreg and thermoplastic prepreg prepared by the same - Google Patents

Abstract

Embodiments of the present invention relate to a method for preparing a thermoplastic prepreg and a thermoplastic prepreg produced by the present invention, and more specifically, to a CNT compound chip having a thermoplastic resin-bonded CNT compound chip uniformly continuously applied to a reinforcing fiber bundle. A method for producing a thermoplastic prepreg in which particles are evenly dispersed and a thermoplastic prepreg produced thereby.

CNT Compound Chip, Thermoplastic, Prepreg, Reinforced Fiber Bundle

Description

A method of preparing thermoplastic prepreg and thermoplastic prepreg prepared by the same

Embodiments of the present invention relate to a method for producing a thermoplastic prepreg and a thermoplastic prepreg produced thereby.

In recent years, prepregs have been widely used in various industrial fields such as aircraft, automobile parts, sports, and leisure. For example, a plurality of reinforcing fiber bundles formed by plural single yarns of reinforcing fibers made of carbon fibers or glass fibers are laid side by side in parallel with each other, and then prepreg formed by impregnating with a thermosetting resin such as epoxy resin or unsaturated polyester. In addition to general industrial materials such as aircraft materials and automobile materials, they are widely used, for example, as molding materials for medical materials and sports leisure applications.

In addition, the prepreg laminate may be manufactured by performing an additional molding step as necessary, laminating two or more prepregs, and then performing a curing and consolidation process. Prepregs or prepreg laminates are usually cured and compacted using heat and vacuum, such as by heat and pressure, or by vacuum bag molding and compression in an autoclave.

Recently, studies on thermoplastic resins that can be separated later are being actively conducted in the case of composite materials instead of thermosetting resins, which are used as base materials for environmental protection. However, thermoplastic resins, unlike thermosetting resins, are difficult to be impregnated on reinforcing materials such as fibrous substrates because of their relatively high viscosity. Therefore, a new prepreg manufacturing process that can compensate for this is recognized as a technical problem.

Embodiments of the present invention by using a compound chip combined with carbon nanotubes (CNT) and a thermoplastic resin (compound chip) not only has excellent bonding strength of the resin and the reinforcing fibers, but also can significantly reduce the peeling phenomenon by external force Provided is a method for producing a leg.

Embodiments of the present invention provide a prepreg having good stiffness and strength produced by the method.

One aspect of the present invention,

Providing a reinforcing fiber bundle;

Providing a release paper;

Supplying a compound chip in which carbon nanotubes (CNT) and a thermoplastic resin are bonded to the reinforcing fiber bundle;

Forming a reinforcing material by primary melting and impregnating the compound chip into the reinforcing fiber bundle using a heating plate; And

It relates to a prepreg manufacturing method comprising the step of secondary melting and impregnating the reinforcing material using an extruder.

Another aspect of the present invention relates to a prepreg having excellent stiffness and strength produced by the method.

According to the embodiments of the present invention, by omitting the resin impregnation process applied to the release paper during prepreg manufacture, the manufacturing process can be simplified to reduce the manufacturing cost, and uniformly continuous to the reinforcing fiber bundles by chipping CNTs having poor dispersibility. By coating, it is possible to produce a thermoplastic prepreg grafted with CNTs. In addition, the prepreg prepared by the embodiments of the present invention is the CNT particles are impregnated between the reinforcing fibers with the resin not only excellent bonding strength of the resin and the reinforcing fibers, but also between the layers and the layers by the CNT particles during the fabrication of the structure The interfacial bonding force of can be increased, and the peeling phenomenon due to external force can be significantly reduced.

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

1 is a view for explaining a step of manufacturing a thermoplastic prepreg according to an embodiment of the present invention. First, the reinforcing fiber bundle 8 is pulled from the unwinder 1 and the release paper is supplied by the release paper supply roll 2.

In one embodiment of the present invention, the reinforcing fiber bundle 8 may be one fiber bundle in which a plurality of single yarns are side by side, or a fiber bundle in which a plurality of fiber bundles are parallel to each other in a sheet form. The type of reinforcing fibers forming the reinforcing fiber bundle 8 is not particularly limited, and carbon fibers, glass fibers, aramid fibers, or the like may be applied. In addition, the release paper may be a paper type coated with heat resistant silicone based on one side or both sides.

Next, the CNT thermoplastic compound chip 4 is uniformly coated on the reinforcing fiber bundle 8 through the rotary chip feeder 3 capable of supplying a pre-fabricated CNT thermoplastic compound chip 4.

CNT thermoplastic compound chip uses thermoplastic resin which is polyethylene resin, nylon resin, polyacetal resin, vinyl chloride resin, polystyrene resin, ABS resin, acrylic resin or mixtures thereof as matrix, and the content ratio of CNT to thermoplastic resin Is 0.1 to 1.5wt% ratio.

CNTs and thermoplastics are mixed using equipment that can be processed into chips, such as extruders. At this time, the surface of the CNT can be chemically treated to increase the bonding strength and dispersion state of the CNT and the thermoplastic resin, and mechanical dispersion using a solvent or a mixer is possible.

As described above, the embodiments of the present invention can simplify the process by omitting the resin impregnation process applied to the release paper when preparing the prepreg using the CNT thermoplastic compound chip 4. In addition, the CNTs with poor dispersibility may be chipped and uniformly applied to the reinforcing fiber bundles, and the CNT particles may be impregnated between the reinforcing fibers together with the resin to increase the bonding strength of the resin and the reinforcing fibers. When the structure is manufactured using the thermoplastic prepreg grafted with CNTs, the interfacial bonding force between the layers is increased by the CNT particles, which may significantly reduce the peeling phenomenon due to external force.

In one embodiment of the present invention, the gear-shaped feeder 5 may be mounted inside the rotary chip feeder 3, whereby a uniform supply of chips is possible. 2 shows an internal view of a rotary chip feeder 3 according to an embodiment of the invention, in which a gear feeder 5 is shown.

In the embodiments of the present invention, the thermoplastic resin bonded to the CNT may further include additives such as a heat stabilizer, a plasticizer, a chemical curing agent, an inorganic filler, a viscosity modifier, and a light stabilizer, as necessary. The thermoplastic synthetic resin composition is preferably insoluble, but is not necessarily limited thereto.

The applied CNT compound chips are then melt impregnated primarily through the heating plate 6, and the resulting reinforcing material is secondary melt impregnated through the upper and lower extruders 7. After cooling the reinforcing fiber bundle with cooling water, a thermoplastic prepreg is formed.

The upper and lower extruders 7 are used in combination of two or more rolls of metal or rubber. In addition, irregularities may be formed in the upper and lower extruders 7 to impart irregularities to the formed thermoplastic prepreg.

According to another embodiment of the present invention, the method may further include heating and rolling the thermoplastic prepreg to smooth the surface of the formed thermoplastic prepreg.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for illustrative purposes only and are not intended to limit the present invention.

Example  1: thermoplastic Prepreg  Produce

Single-walled carbon fiber was used as a fibrous base material for the preparation of the thermoplastic prepreg, and a silicon coated paper was used as a release paper, and a CNT thermoplastic compound chip having a CNT content of 0.5 wt% was used.

As shown in Figure 1, while releasing the carbon fiber fabric, the release paper was fed. Subsequently, the CNT thermoplastic compound chip was evenly applied on top of the reinforcing fiber through the rotary chip feeder. Next, the applied CNT compound chip was melt impregnated primarily through a heating plate, and the resulting reinforcing material was secondary melt impregnated through an up and down extruder. The primary melting temperature is typically above Tg-5 ℃ and below Tg + 20 ℃, and the secondary melt impregnation through extrusion generally has a temperature range of Tm-10 ℃ and above Tm + 20 ℃ and pressure. Is in the range of 0 to 20 kg / cm ² .
After cooling the carbon fiber fabric with cooling water to prepare a thermoplastic prepreg.
The prepared prepreg is first dispersed in the thermoplastic resin, and then in the form of chips into the prepreg manufacturing process, by dispersing the prepreg in the resin, which is a conventional method or applying the CNT in the prepreg manufacturing process Control of CNT content and uniform dispersion can be ensured.

1 is a view for explaining a step of manufacturing a thermoplastic prepreg according to an embodiment of the present invention.

Figure 2 is an internal view of a rotary chip feeder according to an embodiment of the present invention.

** Description of the main symbols in the drawings **

1: unwinder 2: release paper feed roll

3: rotary chip feeder 4: CNT thermoplastic compound chip

5: gear shape feeder 6: heating plate

7: top and bottom extruder 8: reinforcing fiber bundle

Claims (9)

Providing a reinforcing fiber bundle; Providing a release paper; Supplying a compound chip in which carbon nanotubes (CNT) and a thermoplastic resin are bonded to the reinforcing fiber bundle by a chip feeder equipped with a rotary feeder having a gear shape therein; Forming a reinforcing material by primary melting and impregnating the compound chip into the reinforcing fiber bundle using a heating plate; And The prepreg manufacturing method comprising the step of secondary melting and impregnating the reinforcing material using an extruder. delete The method of claim 1, wherein the reinforcing fiber bundle is a single fiber bundle having a plurality of single yarns side by side. 4. The method according to claim 3, wherein the reinforcing fiber bundle is a fiber bundle in which one fiber bundle is formed in a plurality of sheets in parallel with each other. The method of claim 1, wherein the reinforcing fiber bundle is formed of at least one member selected from the group consisting of carbon fibers, glass fibers, and aramid fibers. The method of claim 1, wherein the thermoplastic resin is at least one thermoplastic polymer selected from the group consisting of polyethylene resin, nylon resin, polyacetal resin, vinyl chloride resin, polystyrene resin, ABS resin, acrylic resin or mixtures thereof. Prepreg manufacturing method to use. The method of claim 1, wherein the content ratio of carbon nanotubes (CNT) to the thermoplastic resin is 0.1 to 1.5 wt%. The method of claim 1, further comprising: heating and rolling the formed thermoplastic prepreg after the second melting and impregnation step to smooth the surface of the thermoplastic prepreg. A prepreg produced by the method of any one of claims 1 and 3 to 8.

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