KR101884606B1 - Epoxy resin composition for fiber reinforced composite with high impact resistance and high strength - Google Patents

Abstract

The present invention relates to an epoxy resin composition comprising 60 to 75 wt% of (A) and 10 to 20 wt% of (B), wherein (A) is a phenol novolak type epoxy resin, (B) is a mixed curing agent of 4,4′-DDS, dicyandiamide and 3-(3,4-dichlorophenyl)-1,1-dimethylurea), (C) is an aromatic thermoplastic resin which can be dissolved in (A) and (D) is a thermoplastic resin having a functional group reactive with the (A), and being soluble in the (A). The epoxy resin composition according to the present invention exhibits excellent physical properties such as high toughness, high strength and high heat resistance using an optimal resin synthesis and compounding technique and a 350°F curing type epoxy curing agent.

Description

TECHNICAL FIELD [0001] The present invention relates to an epoxy resin composition for a composite material having high impact resistance and high strength properties,

The present invention relates to an epoxy resin composition, and more particularly, to an epoxy resin composition and compounding technique suitable for use as a material for advanced transportation equipment such as aerospace components and structures requiring high impact resistance and high strength, To a prepreg excellent in toughness, high strength and high heat resistance using a curing agent.

The prepreg is a fiber-reinforced composite material produced by a combination of a fiber and a matrix mainly composed of a resin. The carbon fiber reinforced composite material composed of carbon fiber and resin has excellent mechanical strength characteristics and is widely used in general industrial applications such as sports, aerospace, automobile body, and the like.

The composite material typically consists of a continuous resin matrix and reinforcing fibers as two major components. Composites are often needed to perform tasks in demanding environments, such as aerospace, where the physical limitations and characteristics of composite components are critically important.

 Pre-impregnated composites (prepregs) are widely used in the manufacture of composite parts. A prepreg is a combination of an uncured resin matrix and a fiber reinforcement, which is a form that is easy to shape and cure into a final composite part. By pre-impregnating the fiber reinforcement with resin, the manufacturer must carefully control the amount and location of the resin impregnated with the fiber network. It is well known that the relative amount of fibers and resin in a composite part and the distribution of resin in the fiber network have a great influence on the structural characteristics of the part. Pre-pressures are a preferred material for use in the manufacture of load-bearing structural components and specifically aerospace composite components such as wings, fuselages, partitions and maneuvers. It is important that these components have sufficient strength, damage tolerance and other requirements generally established for this.

Conventional prepresses are well suited for intentional use in providing strong, damage-tolerant composite parts, but require a higher level of strength (e.g., tensile and compressive strength), damage tolerance (CAI) And interlaminar fracture toughness (GIc and GIIc). It is still a continuing need to provide prepregs that can be used to prepare composite parts having interlaminar fracture toughness (GIc and GIIc).

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an optimal resin synthesis and compounding technique for producing a composite material having tensile strength, compressive strength, damage tolerance and interlaminar fracture toughness.

The present invention is an epoxy resin composition comprising the following components, which contains 60 to 75% by weight of (A) and 10 to 20% by weight of (B).

(B): a mixed curing agent of 4,4'-DDS and dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea, (C) an epoxy resin of phenol novolak type, ): An aromatic thermoplastic resin which can be dissolved in (A), (D) a thermoplastic resin which has a functional group reactive with (A) and can be dissolved in (A).

The content ratio of 4,4'-DDS, dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea constituting the mixed curing agent of the epoxy resin composition of the present invention is 6: 1: The ratio of 4,4'-DDS to epoxy equivalent ratio is preferably 50%, dicyandiamide 29% and 3- (3,4-dichlorophenyl) -1,1-dimethylurea 21% Do.

The aromatic thermoplastic resin (C) constituting the epoxy resin composition of the present invention may be one or more resins selected from the group consisting of polyarylate, polysulfone, polyetherimide, polyethersulfone, polyamideimide and polyimide Average molecular weight of 10,000 or more and a glass transition temperature of 150 ° C or more.

The thermoplastic resin (D) of the present invention is preferably a convex copolymer or graft copolymer composed of a commercial part and a non-commercial part in the epoxy resin, and preferably has a number average molecular weight of 2,000 to 20,000.

Further, the present invention provides a prepreg made from the above epoxy resin composition.

The epoxy resin composition according to the present invention exhibits excellent physical properties such as high toughness, high strength and high heat resistance using an optimal resin synthesis and compounding technique and a 350 경 curing epoxy curing agent.

Hereinafter, the high-tough epoxy resin composition and prepreg of the present invention will be described in detail.

The epoxy resin composition of the present invention is composed of the following components, and contains 60 to 75% by weight of (A) and 10 to 20% by weight of (B).

(A): phenol novolac type epoxy resin,

(B): a mixed curing agent of 4,4'-DDS and dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea,

(C): an aromatic thermoplastic resin which can be dissolved in (A)

(D): a thermoplastic resin having a functional group reactive with (A), and being soluble in (A).

The epoxy resin (A) used in the present invention is a phenol novolak type epoxy resin, which is a reaction product containing a polyfunctional epoxy compound as a main component. The phenol novolak type epoxy resin can be obtained by reacting phenol novolak resin obtained from phenol and formaldehyde with epichlorohydrin or methyl epichlorohydrin.

In the present invention, the content of the epoxy resin is preferably in the range of 60 to 75 parts by weight based on 100 parts by weight of the resin composition in view of the mechanical strength of the prepreg. When the content of the epoxy resin is less than 60 parts by weight, moldability is poor. When the amount is more than 75 parts by weight, the epoxy resin does not have adequate physical properties such as tensile strength for composites.

As the curing agent used in the epoxy resin composition of the present invention, any compound having an active group capable of reacting with an epoxy group can be used. Examples of the amine-based curing agent include aliphatic amines such as ethylenediamine, ethylenetriamine, triethylenetetramine, hexamethylenediamine and m-xylenediamine, meta-phenylenediamine, diaminodiphenylmethane, diaminodiethyldiphenyl Aromatic amines such as methane and diamino diethyldiphenyl sulfone, tertiary amines such as benzyldimethylamine, tetramethylguanidine and 2,4,6-tris (dimethylaminomethyl) phenol, and basic amines such as dicyandiamide Hydrogen compounds and organic acid dihydrazides such as adipic acid dihydrazide, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole. Examples of the acid anhydride-based curing agent include aliphatic acid anhydrides such as polyadipic acid anhydride, poly (ethyloctadecanedioic acid) anhydride and poly sebacic acid anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylcyclohexene dicarboxylic acid anhydride Alicyclic acid anhydrides such as trimellitic anhydride, trimellitic anhydride, pyromellitic anhydride, and glycerol tristrimellitate, and halogen-based acid anhydrides such as anhydrous hic acid and tetrabromophthalic anhydride. have. In the present invention, since it is cured at a relatively low temperature and the storage stability is good, a basic active hydrogen compound can be preferably used in the amine curing agent as a curing agent. In addition, as a curing agent suitable for the epoxy resin composition of the present invention, 4,4'-diaminodiphenylsulfone (DDS) is included.

As the hardening accelerator, it is preferable to use dicyandiamide, and it is preferable to use 2 to 6 parts by weight, and it is most preferable to use 1 to 3 parts by weight. The curing can be caused by the latent amine type curing agent, but the curing time can be greatly shortened by a small amount of catalyst, that is, a curing accelerator. As such, it is to be understood that the term catalyst and cure accelerator refers to a chemical that shortens the curing time achievable with the curing agent alone. As the urea catalysts used to complete the shortening of the curing time exceeding the previous expectations, 3,3 '- (4-methyl-1,3-phenylene) bis (1,1-dimethylurea) - (3,4-dichlorophenyl) -1,1-dimethylurea. The catalyst is used in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, most preferably 0.5 to 3 parts by weight.

The mixed curing agent containing the curing accelerator is preferably 10 to 20 parts by weight based on 100 parts by weight of the total of the resin composition. If the amount of the curing agent containing the curing accelerator is less than 10 parts by weight, the curing rate will be adversely affected. If the amount is more than 20 parts by weight, the moldability is poor.

In the present invention, the content ratio of 4,4'-DDS, dicyandiamide, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea constituting the mixed curing agent is 6: 1: 1 to 12: 2 : 1 is preferable. Also, in the present invention, the mixed curing agent of 4,4'-DDS and dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea has a ratio of 4,4'-DDS of 50% , 29% of dicyandiamide and 21% of 3- (3,4-dichlorophenyl) -1,1-dimethylurea are most preferable.

The composite material typically consists of a continuous resin matrix and reinforcing fibers as two major components. Composites are often needed to perform tasks in demanding environments, such as aerospace, where the physical limitations and characteristics of composite components are critically important.

The tensile strength of the cured composite material is largely dependent on the individual properties of the reinforcing fibers and the matrix resin as well as by the interaction between these two components. In addition, fiber-resin composition ratio is an important factor. The cured composites under tensile forces tend to fail through the mechanism of cumulative loss resulting from multiple tensile failure of individual fiber filaments located in the reinforcing tow. If the stress level of the resin adjacent to the broken filament end becomes very large, the entire composite can be broken. Therefore, the fiber strength, the strength of the matrix, and the stress dissipation efficiency near the destroyed filament end will contribute to the tensile strength of the cured composite.

In many applications, it is desirable to maximize the tensile strength properties of the cured composite. Attempts to maximize tensile strength, however, can often have negative effects on other desirable properties, such as compressive performance and damage tolerance of the composite structure. In addition, attempts to maximize tensile strength can have unexpected effects on the tack and outlife of the prepreg. The stickiness or tackiness of the uncured prepreg is generally referred to as "tack ". The viscosity of the uncured prepreg is an important consideration in lay up and molding operations. A prepreg with little or no viscosity is difficult to fabricate with a laminate that can be molded to make structurally robust composite parts. On the contrary, a prepreg having a very high viscosity is difficult to handle, and it may also be difficult to position it on a mold. The prepreg preferably has a suitable amount of viscosity to ensure easy handling and excellent laminate / molding characteristics. In any attempt to increase the strength and / or damage tolerance of the cured composite material provided, it is important to maintain the viscosity of the uncured prepreg within acceptable limits to ensure proper prepreg handling and molding.

The "out-life" of the prepreg is a period during which the prepreg can be exposed to ambient conditions before it is cured to an unacceptable degree. The out-life of the prepreg can vary widely depending on various factors, but is mainly controlled by the resin formulation used. The prepreg out-life should be long enough so that routine handling, layup, and molding operations are performed without curing the prepreg to an unacceptable degree. In any attempt to increase the strength and / or damage tolerance of the cured composite material provided, the out-life of the uncured prepreg allows sufficient time for processing, handling and laying up the prepreg before curing It is important to be as long as possible.

The most common way to increase the tensile performance of a composite is to change the surface of the fiber to weaken the bond strength between the matrix and the fiber. This can be achieved by reducing the amount of electro-oxidized surface treatment of the fibers after graphitization. Reducing the matrix fiber bond strength causes a mechanism for stress dissipation at the filament ends exposed by interfacial separation. This interfacial separation increases the amount of tensile loss that a composite component can withstand before it loses its tensile strength.

Alternatively, applying a coating or "size" to the fibers can reduce the resin-fiber bond strength. This method is well known in glass fiber composites, but can also be applied to composites reinforced with carbon fibers. By using these strategies, it is possible to significantly increase the tensile strength. However, this improvement entails a decrease in properties such as compression after impact (CAI) strength, which requires a high bond strength between the resin matrix and the fibers.

Another alternative is to use a lower coefficient matrix. Having a low coefficient resin reduces the stress level to be formed in the vicinity of the broken filament. This may be accomplished by selecting a resin that is usually inherently lower in modulus (e.g., cyanate ester) or by selecting an elastomer (carboxy-terminated butadiene-acrylonitrile [CTBN], amine- terminated butadiene- acrylonitrile [ATBN], etc.). Combinations of these various methods are also known.

Choosing a lower coefficient resin may be effective in increasing the composite tensile strength. However, this can lead to propensity for damage tolerance, which is typically measured by compression properties, such as impact-after-compression (CAI) strength and reduced open hole compression (OHC) strength. Therefore, it is very difficult to simultaneously increase both the tensile strength and the damage tolerance.

Multiple layers of prepreg are typically used to produce composite parts having laminated structures. The detachment of such composite parts is an important failure mode. Peeling occurs when the two layers are separated from each other. Important design constraints include both the energy required to initiate delamination and the energy required to propagate delamination. The onset and advancement of delamination is often determined by examining Method I and Method II fracture toughness. Fracture toughness is usually measured using a composite material with unidirectional fiber orientation. The interlaminar fracture toughness of the composite material is quantified using Glc (Double Cantilever Beam) and G2c (End Notch Flex) tests. In Method I, the pre-cracked laminate fracture is subjected to a peel force, and in Method II, the crack is advanced by a shear force. G2c interlaminar fracture toughness is related to CAI. The prepreg material exhibiting high damage tolerance also has a high CAI and G2c value.

A simple way to increase the interlaminar fracture toughness was to increase the ductility of the matrix resin by introducing a thermoplastic sheet as an insert between the prepreg layers. However, in this method, it is easy to obtain a hard and viscous material which is difficult to use. Another method is to include a layer of hard resin between about 25 to 30 microns thick between the fibrous layers. The prepreg product comprises a resin rich surface containing fine, hard thermoplastic particles. For layer-hardened materials, the initial value of the Method II fracture toughness is about four times higher than the value of the carbonless prepreg without the interlayer, but the fracture toughness value decreases as the crack spreads and converges at low values, It is almost identical to the value of the system without inserts. As a result, the average G2c value becomes highest as the cracks move from the very hard interlayer (resin-enriched) region of the composite to the less hard interlayer (fiber) region.

Conventional prepresses are well suited for intentional use in providing strong, damage-tolerant composite parts, but require a higher level of strength (e.g., tensile and compressive strength), damage tolerance (CAI) And interlaminar fracture toughness (GIc and GIIc). It is still a continuing need to provide prepregs that can be used to prepare composite parts having interlaminar fracture toughness (GIc and GIIc).

In order to solve the above problems in the present invention, the aromatic thermoplastic resin (C) and the thermoplastic resin (D) are used together with the epoxy resin (A) and the mixed curing agent (B) to provide a remarkable toughness, high heat resistance, , A resin composition having physical stability can be obtained.

The aromatic thermoplastic resin (C) is an aromatic thermoplastic resin dissolved in the epoxy resin (A). Specific examples of the resin include polyarylate, polysulfone, polyetherimide, polyether sulfone, polyamideimide and polyimide, and resins having good heat resistance. Polyethersulfone is most preferred in the present invention. An aromatic thermoplastic resin having a number average molecular weight of 10,000 or more and a glass transition temperature of 150 占 폚 or more is preferable. When the number average molecular weight is less than 10,000 or the glass transition temperature is less than 150 ° C, it is not preferable from the viewpoint of the mechanical properties of the composite material.

The thermoplastic resin (D) is preferably a convex copolymer or a graft copolymer having both a commercial portion and an emergency portion in the epoxy resin. Specifically, a block copolymer composed of a polyimide skeleton, a polyamide skeleton, a polysulfone skeleton or a polyether sulfone skeleton having compatibility with an epoxy resin and a chain composed of an epoxy resin and a siloxane skeleton or nitrile rubber having inherently incompatibility or Graft copolymer. Particularly, block copolymers composed of a siloxane skeleton and a polyimide skeleton are suitable for composite materials for aviation because they have a high toughness improving effect and low water wettability. Further, by appropriately adding the thermoplastic resin (D), it becomes possible to control the size of the dispersed phase, and a cured product having high toughness, which could not be obtained in the past, can be obtained. The number average molecular weight of the thermoplastic resin (D) is preferably 2,000 to 20,000. When the number average molecular weight of the thermoplastic resin (D) is less than 2,000, it is difficult to obtain the effect of improving the toughness. When the number average molecular weight is more than 20,000, it is not preferable from the viewpoint of the mechanical properties of the composite material.

The content of the aromatic thermoplastic resin (C) and the thermoplastic resin (D) is preferably 10 to 30 parts by weight in the resin composition. When the amount is less than 10 parts by weight, the effect of improving toughness is not obtained. When the amount is more than 30 parts by weight, there is a problem that the handling property is poor.

Next, the prepreg of the present invention will be described. By impregnating the reinforcing fiber with the embodiment of the resin composition, a prepreg containing the embodiment of the epoxy resin composition as a matrix resin in the form of a cured product can be obtained.

The prepreg of the present invention is obtained by impregnating the resin composition with the reinforcing fiber. There are no specific limitations or restrictions on the type of reinforcing fibers used and a wide variety of fibers are used, including glass fibers, carbon fibers, graphite fibers, aramid fibers, boron fibers, alumina fibers and silicon carbide fibers. Two or more of these fibers may be used in combination. The shape and arrangement of the reinforcing fibers are not limited, and for example, fibrous structures such as long fibers aligned in one direction, single tows, fabrics, knits, nonwoven fabrics, mats and braids are used.

Particularly, in applications where the weight of the material is required to be high or the strength thereof is high, carbon fibers can be suitably used because of its excellent non-elasticity ratio and non-elasticity. Therefore, carbon fiber is preferred in the present invention.

The carbon fiber preferably used in the present invention may be any kind of carbon fiber, but is preferably carbon fiber having a tensile modulus in the range of 200 to 300 GPa from the viewpoint of interlayer toughness and impact resistance. The resin composition preferably has a minimum viscosity at 100 to 150 DEG C of 1.0 Poise and a support of 2.5 Poise or less.

The resin composition is expected to have a viscosity of 5,000 to 10,000 Paise or less at 30 占 폚. A resin composition having a viscosity of 10,000 Paise or less is preferable, and has various desirable characteristics of a prepreg.

It is also preferable that the average epoxy equivalence of the resin composition is 200 to 300. To achieve this preferred range of average epoxy equivalents, a high molecular weight resin (e.g., molecular weight greater than 1,000) and a low molecular weight (e.g., less than 200 molecular weight) resin are mixed.

The prepreg of the present invention is preferably impregnated with the reinforcing fiber, and the reinforcing fiber mass fraction of the prepreg is preferably 35 to 65 parts by weight. If the weight of the reinforcing fiber is excessively low, the resultant composite material becomes excessively massive, and the advantage of the fiber reinforced composite material excellent in the non-rigidity and the non-elasticity ratio adversely affects. If the weight of the carbon fiber is excessively high, , The resulting composite material tends to have a large void, and its mechanical properties may be significantly lowered.

The prepreg produced by the above method has a tear strength of 10 to 13 in-lbf / in ² and a compressive strength of 1200 MPa or more at the time of wet heat, and is excellent in toughness and wet heat compression strength and is used as a composite material for aerospace components .

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

Next, the FRP material is described. The FRP material can be produced by using a method such as a prepreg lamination and molding method, a resin transfer molding method, a resin film injection method, a hand lay up method, a sheet molding compound method, a filament winding method and a drawing forming method, The present invention is not limited thereto.

The resin transfer molding method is a method in which a reinforcing fiber resin base material is directly impregnated with a liquid thermosetting resin composition and cured. Since this method does not involve intermediate products such as prepregs, it has a great potential for reducing molding costs and is advantageously used for the production of structural materials such as spacecraft, aircraft, railway vehicles, automobiles, and marine vessels.

The prepreg lamination and shaping process includes forming and / or laminating the prepreg or prepregs produced by impregnating the reinforcing fiber base material with the thermosetting resin composition, and then forming and / or laminating the formed and / or laminated prepreg / The resin is cured by applying pressure to obtain FRP material.

The filament winding method includes laminating one to several tens of reinforcing fiber rovings around a rotating metal core (mandrel) under a tension at a predetermined angle, so that one to several tens of reinforcing fiber rovings are stretched together in one direction and impregnated with a thermosetting resin composition . After the lap of the roving reaches a predetermined thickness, it is cured and then the metal core is removed.

The draw-forming method is a method in which the impregnation tank filled with the liquid thermosetting resin composition for impregnating the reinforcing fiber with the thermosetting resin composition is successively passed through a squeeze die and a heating die for molding and curing and is continuously stretched using a tensile machine . This method is used in the manufacture of FRP materials for fishing rods, rods, pipes, sheets, antennas, building structures, etc., since it provides the advantage of continuously forming FRP materials.

Of these methods, prepreg lamination and molding methods can be used to provide excellent stiffness and strength to the obtained FRP material.

The prepreg may contain embodiments of epoxy resin compositions and reinforcing fibers. This prepreg can be obtained by impregnating the reinforcing fiber base material with the epoxy resin composition disclosed herein. The impregnation method includes a wet method and a hot-melt method (dry method).

In the wet method, first, the reinforcing fiber is immersed in a solution of the epoxy resin composition produced by dissolving the epoxy resin composition in a solvent such as methyl ethyl ketone or methanol, and recovered. Then, the solvent is removed through evaporation by an oven or the like, Is impregnated with an epoxy resin composition. The hot melt method is a method of directly impregnating reinforcing fibers with a fluid epoxy resin composition by preliminary heating or by first coating a release paper piece or pieces with an epoxy resin composition for use as a resin film, , And then applying heat and pressure to impregnate the reinforcing fibers with the resin. The hot melt process can provide a prepreg that has virtually no residual solvent.

The reinforcing fiber cross-sectional density of the prepreg may be 50 to 200 g / m < 2 >. If the cross-sectional density is at least 50 g / m < 2 >, it may be necessary to laminate a small number of prepregs in order to fix a predetermined thickness in forming the FRP material, which can simplify the lamination operation. On the other hand, if the cross-sectional density is 200 g / m 2 or less, the drape property of the prepreg can be excellent. The reinforcing fiber mass fraction of the prepreg may be from 60 to 90 mass% in some embodiments, from 65 to 85 mass% in some embodiments, or even from 70 to 80 mass% in yet another embodiment. If the reinforcing fiber mass fraction is at least 60% by weight, there is a sufficient fiber content, which not only provides the advantages of the FRP material in terms of good non-strength and inelastic modulus, but also that the FRP material generates too much heat during the curing time . If the reinforcing fiber mass fraction is 90 mass% or less, the resin impregnation can be satisfactory and the risk of forming many voids in the FRP material is reduced.

A press forming method, an autoclave forming method, a bagging forming method, a lapping tape method, an internal pressure forming method and the like can be suitably used for applying heat and pressure under prepreg lamination and forming method.

In the autoclave molding method, a prepreg is laminated on a tool plate of a predetermined shape, then covered with a bagging film, and then air is drawn out from the laminate, and heat and pressure are applied to perform curing. This not only allows precise control of the fiber orientation, but also provides a high quality molding material with excellent mechanical properties due to the minimum void content. The pressure applied during the molding process may be 0.3 to 1.0 MPa, while the molding temperature may be in the range of 90 to 200 < 0 > C.

The lapping tape method is a method of forming a tubular FRP material by lapping a mandrel or any other shim around the removed rod with a prepreg. This method can be used to manufacture golf shafts, fishing rods, and other rod products. In a more specific expression, this method involves lapping the mandrel around with a prepreg, lapping with a lapping tape made of a thermoplastic film on the prepreg under tension and fixing the prepreg, and applying pressure thereto. After curing the resin through heating in the oven, the roughened rod is removed to obtain a tubular body. The tension used for wrapping with the lapping tape may be 20 to 78 N. The forming temperature may range from 80 to 200 캜.

The internal pressure forming method is a method in which a preform obtained by lapping a thermoplastic resin tube or any other internal pressure-applying device with a prepreg is placed inside a metal mold, and then a high-pressure gas is introduced into the internal pressure-applying device to apply pressure, Simultaneously, the metal mold is heated to mold the prepreg. This method can be used when forming objects having complex shapes, such as golf shafts, bats, and tennis or badminton racquets. The pressure applied during the molding process may be 0.1 to 2.0 MPa. The forming temperature may be from room temperature to 200 캜 or from 80 to 180 캜.

FRP materials produced from prepregs may have Class A surfaces as mentioned above. Class A surfaces are surfaces that exhibit extremely high finish quality characteristics without aesthetic flaws and defects.

The cured epoxy resin composition obtained from the epoxy resin composition and the FRP material containing the reinforcing fibers are advantageously used in sports applications, general industrial applications, and aerospace applications. Specific sports applications in which such materials are advantageously used include golf shafts, fishing rods, tennis or badminton racquets, hockey sticks and ski poles. Specific general industrial applications in which such materials are advantageously employed include structural materials of vehicles such as automobiles, bicycles, marine vessels and railway vehicles, drive shafts, leaf springs, wind mill blades, pressure vessels, flywheels, And repair / reinforcement materials.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

Example 1

The phenol novolak epoxy resin is heated from room temperature (25 ° C) to 120 ° C at a rate of 2 ° C / min. Then, the solution is poured into a solution of solvay PES and maintained at a temperature of 120 ° C for 1 hour. After the PES particles are completely melted, a siloxane polyimide copolymer having a number average molecular weight of 15,000 is added and mixed homogeneously for 0.5 to 1 h. The PES and siloxane polyimide particles used herein were mixed with 5 탆 particles pulverized through a ball mill, and the viscosity of the compound was 0.2 poise / min at 180 캜. After the temperature of the mixture was reduced to 2 캜 / min, the curing agent containing 4,4'-DDS and dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea was stirred evenly within 10 minutes Respectively. At this time, the ratio of the compound constituting the mixed curing agent was 10: 2: 1. The final formulation has a viscosity at 30 ° C of 5000 to 10,000 poise, and at 130 ° C it forms 10 to 100 posie.

Examples 2 to 5 and Comparative Example 1

A resin composition was prepared in the same manner as in Example 1, except that the content of the resin composition was changed as shown in Table 1.

Comparative Example 2

A resin composition was prepared in the same manner as in Example 1 except that only 4,4'-DDS was used as a curing agent.

Preparation of prepreg

The resin composition thus compounded is applied to a release paper to prepare a resin sheet.

The resin unit weight applied to release paper was 59g / m 2 resin paper. Next, a unidirectional prepreg was obtained by impregnating both sides of the carbon fiber with resin paper in one direction by heating and pressing.

Measurement of compressive strength during wet heat

The unidirectional prepregs prepared in the examples and comparative examples were laminated by aligning the fibers in a direction of 12 pl and molded at a temperature of 180 ° C for 2 hours under a pressure of 0.59 MPa at a temperature raising rate of 1.5 ° C / Thereby producing a laminate. A test piece having a total length of 80.8, a thickness of 1.2 mm, a width of 12.8 mm, and a length of 38.0 mm attached on both sides was produced from this laminate. At this time, a test piece was prepared so that the longitudinal direction of the test piece and the fiber direction were parallel. This specimen was immersed in hot water at 71 ° C for 14 days. The test piece was measured at 0 ° compression strength at 82 ° C using a universal testing machine equipped with a thermostatic chamber according to JIS K 7076 (1991). The number of samples was 5.

Shear mode interlaminar fracture toughness (GIIc) test of composites

For preparing the GIIc specimen, 20 sheets of the prepreg were stacked in one direction, and molding with a normal autoclave was carried out at 180 DEG C for 2 hours and at a pressure of 6 bar. Thereafter, the specimens were prepared by cutting at a size of 0.5 inches in the direction of 13 degrees and 90 degrees in the direction of 0 degrees.

The test specimens were used to carry out the evaluation according to the test procedure of BMS 8-276. At this time, five specimens were evaluated and the average values were recorded in Table 1.

Measurement of compressive strength (CAI) after impact of composite material

Twenty-four prepregs were laminated with (+ 45/0 / -45 / 90) 3S to prepare a CAI specimen. Molding with a normal autoclave was carried out at 180 DEG C for 2 hours and at a pressure of 6 bar. The specimens were cut into 4 inches by 6 inches long.

After five test specimens were prepared, the impact test was carried out at a 270 in-lbf impact level, and a compression test was conducted. The average values were recorded in Table 1.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Composition content Epoxy 66 66 62 70 61 49 62 Mixed hardener 14 14 19 9 20 16 19 Aromatic thermoplastic resin 15 5 14 15 13 21 14 Thermoplastic resin 5 15 5 6 6 14 5 Carbon Fiber IMS60 IMS60 IMS60 IMS60 IMS60 IMS60 IMS60 Compressive strength during wet heat
(MPa) 1230 1200 1210 1120 1080 1070 1110 G _II c
(in-lbf / in ² ) Avg. 11.19 12.01 12.11 8.91 5.10 8.32 6.28 CAI (ksi) (270 in-lbf impact level) Avg. 47.72 46.27 46.11 45.07 38.92 42.28 40.92

As shown in Table 1, Examples 1 to 5 according to the present invention showed superior compressive strength, interlaminar toughness and fracture toughness after impact than the Comparative Examples.

Claims (5)

(A), (B) is 14 to 19 parts by weight, (C) and (D) is 19 to 20 parts by weight, and the following components The content ratio of 4,4'-diaminodiphenylsulfone (DDS), dicyandiamide, and 3- (3,4-dichlorophenyl) -1,1-dimethylurea is 6: 1: 1 to 12: 2: 1. ≪ / RTI >
(A): phenol novolak type epoxy resin
(B): A mixed curing agent of 4,4'-diaminodiphenylsulfone (DDS), dicyandiamide and 3- (3,4-dichlorophenyl) -1,1-dimethylurea
(C): an aromatic thermoplastic resin soluble in (A)
(D) a thermoplastic resin having a functional group reactive with (A), which is soluble in (A), and which is composed of a siloxane skeleton and a polyimide skeleton and has a number average molecular weight of 2,000 to 20,000
The method according to claim 1,
The aromatic thermoplastic resin (C) comprises one or more resins selected from the group consisting of polyarylate, polysulfone, polyetherimide, polyether sulfone, polyamideimide and polyimide, and has a number average molecular weight of 10,000 or more , And a glass transition temperature of 150 ° C or higher. delete delete A prepreg produced from the epoxy resin composition of claim 1.