KR20160054644A - Process of producing high-tenacity hybrid uni-direction prepreg - Google Patents

Abstract

The present Invention relates to a producing method of a high strength hybrid uni-directional prepreg which applying a coating agent on a front surface and a rear surface of fiber yarns by providing fibers which alternately arrange carbon fiber yarns and aramid fiber yarns. The hybrid uni-directional prepreg having excellent physical properties such as high torsional stiffness and high damage tolerance is provided during deformation caused by external force. Lifespan of a composite tube can be improved by preventing shear failure and delamination, and lighter weight and impact strength can be improved.

Description

TECHNICAL FIELD [0001] The present invention relates to a high-strength hybrid unidirectional prepreg,

The present invention relates to a method for producing a high-strength hybrid unidirectional prepreg by supplying fibers arranged alternately with carbon fiber yarns and aramid fiber yarns, applying a coating agent to the front and back surfaces of the fiber yarns and drying the same.

The application of composite materials using textile materials in relation to sporting goods started with the application of GFRP (Glass Fiber Reinforced Plastics) of Ski in the late 1960s, Carbon Fiber Reinforced Plastics (CFRP) to golf clubs in the early 1970s, Various advanced materials are being used. Particularly, in the bicycle related industry, the use of composite materials using fiber materials was first applied to carbon fiber bicycle frames in bicycle frames in the mid 1970s, and in the 1980s, the use of bicycle frames using fibrous composite materials Research on utilization has been concentrated.

In accordance with the development of the mechanical performance of material fibers such as carbon fiber, boron fiber and aramid fiber, and in order to meet the demands of light weight of sports equipment and excellent mechanical properties, As a next-generation material to replace.

In addition, most of the composite bicycles are made of carbon fiber composite material, which is weak to impact due to the characteristics of the carbon fiber composite material. When riding a bicycle, it is often the case that the stones bump into the frame, especially in the lower part, the down tube and the chain stay, and in the case of a frame made of a carbon composite material, Or cracks may occur. In order to improve the strength of the impact, it was considered necessary to develop a bicycle frame using aramid fiber. However, the aramid fiber alone has a problem that the bicycle does not satisfy the strength and stiffness required by the frame.

Korean Patent Publication No. 10-2014-0044502 (published April 15, 2014)

Therefore, according to the present invention, since the bicycle can not satisfy the strength and rigidity required by the frame only by using the aramid fiber or the carbon fiber alone, the hybrid material is provided to develop the frame to solve the problems of impact, And to provide a hybrid prepreg which is capable of producing a hybrid prepreg.

Therefore, according to the present invention, After the molten coating agent is applied to the surface of the release paper to supply the coating sheet,

Carbon fiber yarns and aramid fiber yarns are alternately arranged and passed over the coating agent on the coating sheet to coat the surface of the fiber yarns with a coating agent,

The back surface of the fiber yarn is again passed over the coating agent on the coating sheet to apply a coating agent to the back surface of the fiber yarns and then dried, thereby drying the fiber yarn.

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

The method for producing a high strength hybrid unidirectional prepreg of the present invention is a method for producing a high strength hybrid unidirectional prepreg, comprising the steps of: applying fibers, in which carbon fiber yarns and aramid fiber yarns are alternately arranged on a coating sheet comprising a release paper coated with a coating agent, And then dried.

The high-strength hybrid unidirectional prepreg produced by the present invention is a prepreg for forming a structural material such as a frame of a road bike. Since the impact strength properties are important, carbon fiber yarns and aramid fiber yarns are used. For optimization, carbon fiber yarns and aramid fiber yarns should be alternately arranged to form unidirectional prepregs. From the viewpoint of a composite material such as a prepreg, the higher the strength of the fiber used as the reinforcing material used to improve the strength of the composite material, the greater the strength against external stress per 1 g / d of fiber. The higher the modulus of elasticity, the higher the ability to disperse external stresses into the entire fiber more rapidly. Therefore, in the present invention, carbon fibers and aramid fibers are alternately arranged because it is important to disperse the impact with appropriate strength.

The carbon fiber yarn may be a conventional carbon fiber yarn used as a reinforcing material. The degree of fineness is preferably from 600 to 15,000 d / 16 to 144 ft. The aramid fiber yarn can be a conventional para-aramid fiber yarn used as a reinforcing material. The fineness having a standard of 200 to 3,000 d / 16 to 144 fila is preferably used in an alternate configuration and is good in impact strength.

The ratio of the carbon fiber yarn and the aramid fiber yarn is preferably in the range of 1: 1 to 1: 4 in terms of the impact strength.

The coating agent is applied to the bundle of mixed fiber yarns in which the carbon fiber yarns and the aramid fiber yarns are alternately arranged. The melted coating agent is applied to the surface of the release paper and is passed through the bundle of mixed fibers, The coating agent is applied to the surface of the substrate.

The coated sheet was prepared by coating a melted coating agent on the surface of a release paper. The coating agent was a mixture of 35 to 50% by weight of phenol novolac epoxy resin, bisphenol A epoxy resin 40 , 2 to 4 wt% of dicyandiamide, and 2 to 4 wt% of dichlorophenyl dimethylurea, based on the total weight of the composition.

The prepreg of the present invention is excellent in workability and form stability and is excellent in impact resistance and is used for frames for road bikes and the like. The thermosetting resin having high heat resistance such as epoxy or unsaturated polyester maintains high viscosity at room temperature, It is preferable to use it as a coating resin. In the case of road bikes, the characteristics of the reinforcing fiber as a structural material is also important, but the nature of the matrix to be reinforced is also an important factor. Therefore, it compensates for the drawbacks of the manufacturer of roadbike composite materials manufactured by high temperature and high- The thermosetting resin used as a matrix is important.

In the case of the epoxy resin, the resin shrinkage is small and the mechanical properties to be provided as a FRC (Fiber Reinforcement Composite) matrix such as dimensional stability and abrasion resistance are superior to other resins. In particular, It is a resin suitable for the manufacture of bicycle frames because it prevents interfacial phenomenon and improves interfacial bonding between fiber and resin by stably controlling B stage in which crosslinking occurs after opening ring reaction of epoxy ring. The phenol novolac epoxy resin is preferably contained in the coating resin in an amount of 35 to 50% by weight. When the content of the phenol novolac epoxy resin is less than 35% by weight, the rigidity is deteriorated. When the content of the phenol novolac epoxy resin exceeds 50% There is a problem in that the impact strength is lowered.

The bisphenol A epoxy resin is preferably contained in an amount of 40 to 60% by weight. When the amount is less than 40% by weight, the impact strength is lowered. When the amount is more than 60% by weight, A problem arises. Polyvinyl formal acts to increase the bonding force between fibers. When the content is less than 1% by weight, the impact strength is lowered due to weak bonding force between the fibers. When the content is more than 2% by weight, Lt; / RTI >

As the curing agent, dicyandiamide is used to improve the curing reactivity, preferably 2 to 4 wt%. It is preferable that the curing accelerator contains dichlorophenyldimethylurea in an amount of 2 to 4% by weight in order to control the curing time.

One of the main characteristics required for the prepreg is the tackiness, which plays a role of smoothly stacking the sheets without being slipped between the stacked layers when a plurality of prepregs are laminated in the forming process. The Tack property can be changed according to the viscosity behavior of the resin after B-stage curing and is influenced by the properties of the functional group, Tg and molecular weight, and affects affinity with the adherend.

Phenol Novolac Epoxy Resin and bis phenol A Epoxy Resin are expected to improve the workability comparatively to other epoxy resins. The degree of hardness or softness of the resin and the bonding of the probe and the resin The initial peak at which the epoxy resin appears is most excellent in the epoxy resin.

The carbon fiber yarns and the aramid fiber yarns are alternately arranged and passed over the coating agent on the coating sheet to apply a coating agent to the surface of the fiber yarns and then the back surface of the fiber yarns is again passed over the coating agent on the release paper, The coating agent is applied to the back surface of the fiber yarns to sufficiently apply the coating agent to the front and back surfaces of the fiber yarns and then dried to produce a high strength hybrid unidirectional prepreg of the present invention.

The prepreg of the present invention is an intermediate molding material of a composite material obtained by impregnating a reinforcing fiber with a resin into a B-stage, and finally, the prepreg is laminated on a mold and cured by heating and pressing to form a frame of a road bike A structural material can be manufactured.

Therefore, it is possible to provide a hybrid unidirectional prepreg having excellent properties such as high torsional rigidity and high damage tolerance at the time of deformation due to external force according to the present invention, to prevent shear fracture and prevent delamination, It is possible to improve the light weight, weight, weight and impact strength.

1 is a photograph of a surface micrograph of a prepreg of the present invention,
2 is a side view of the prepreg of the present invention.

The following examples illustrate non-limiting examples of making the hybrid unidirectional prepreg of the present invention.

[Example 1]

44.5% by weight of phenol novolac epoxy resin, 47% by weight of bisphenol A epoxy resin, 1.5% by weight of polyvinyl formal, 4% by weight of dicyandiamide, And 3% by weight of dichlorophenyldimethylurea was melted (90 DEG C), stirred for 5 minutes, and then charged into a resin-coated bath (85 DEG C). The UD machine was operated to coat the release resin with the mixed resin (coating agent) on the primary resin coated part. Then, a carbon fiber yarn (14,850d / 16fila, toray still), an aramid fiber yarn (1500d / 144fila, In a ratio of 1: 1 by volume, and then applying the coating agent on the surface of the fiber yarn, applying a release agent coated with a coating agent on the back surface of the fiber yarn, applying a coating agent to the fiber yarn Cooling, and winding.

The surface of the prepared prepreg is shown in Fig. 1, in which the resin is applied to the entire hybrid prepreg in which the aramid fiber and the carbon fiber are intersected at regular intervals, and there is no boundary line between the aramid and the carbon. , It was confirmed that the resin was uniformly impregnated between the fibers.

The prepreg was cut to 150 mm × 100 mm for the impact strength test of the prepreg, and then a plurality of sheets were stacked and then put into a mold and molded at a temperature of 150 ° C. under a pressure of 1000 psi using a hot press. The laminate was cut according to its thickness, length and width and measured using a drop impact tester.

[Comparative Example 1]

A prepreg was prepared in the same manner as in Example 1, except that the constituent fibers were used only as carbon fibers.

(Impact strength: 0.77 to 4.65 m / s, falling height: 0.03 to 1.10 m, falling weight: 1.00 to 37.5 kg , Impact specifications were measured using ASTM 3763, ISO 6603-2-Puncture, ISO 179, ASTM D 6110-Charpy, ISO 180, ASTM D 256-Izod.

As shown in Table 1, the impact properties showed a higher impact strength value than that of Comparative Example 1, which is a carbon composite material (CFRP), due to the influence of aramid.

division Peak Force (N) Total Energy (J) Example 1 9,233.84 (47% increase) 42.38 (26% increase) Comparative Example 1 4,912.00 31.20

Claims (3)

After the molten coating agent is applied to the surface of the release paper to supply the coating sheet,
Carbon fiber yarns and aramid fiber yarns are alternately arranged and passed over the coating agent on the coating sheet to coat the surface of the fiber yarns with a coating agent,
Wherein the back side of the fiber yarn is passed over the coating agent on the coating sheet to apply a coating agent on the back side of the fiber yarns and then dried. The coating composition according to claim 1, wherein the coating agent comprises 35 to 50% by weight of a phenol novolac epoxy resin, 40 to 60% by weight of a bisphenol A epoxy resin, a polyvinyl formal, 1 to 2% by weight of dicyandiamide, 2 to 4% by weight of dicyandiamide, and 2 to 4% by weight of dichlorophenyldimethylurea. The method of claim 1, wherein the ratio of the carbon fiber yarn to the aramid fiber yarn is 1: 1 to 1: 4 by volume.

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