KR101898394B1 - Towpreg including epoxy resin composition - Google Patents

Abstract

According to an embodiment of the present invention, provided is an epoxy resin composition, comprising: an epoxy resin; and a cyanamide, wherein the cyanamide includes 5-20 parts by weight based on 100 parts by weight of the epoxy resin. According to the present invention, the adhesion between a reinforcing fiber and a thermosetting resin composition is excellent, and thus high interlaminar shear strength can be exhibited.

Description

TOWPREG INCLUDING EPOXY RESIN COMPOSITION comprising an epoxy resin composition < RTI ID = 0.0 >

The present invention relates to an epoxy resin composition and a toffee containing the same.

Fiber-reinforced composites containing thermosetting resins together with reinforcing fibers are lightweight and have excellent mechanical and chemical properties, and thus have been applied in many fields such as air, automobiles, ships, construction, sporting goods, and the like.

Such a fiber reinforced composite material is mainly used as a prepreg which is an intermediate substrate impregnated with a thermosetting resin in a reinforcing fiber. Among them, thousands of tens of thousands of filaments are arranged in one direction, and a bundle of reinforcing fibers is laminated with a thermoplastic resin impregnated towpreg ) Are particularly suitable for producing hollow structures.

Toupureg is used to impregnate and semi-cure a thermosetting resin in a bundle of reinforcing fibers, wrapping it in a bobbin without laminating the release paper, etc., and storing and holding a toe prgram wrapped around the bobbin. At the same time, proper tack and good drape are needed to prevent the occurrence of fiber fleece during marine operation.

Therefore, there is a need to develop a toe proge technique which is excellent in storage stability and heat resistance, excellent in marine property from bobbins, process stability and drape, and excellent in adhesion between reinforcing fiber and thermosetting resin composition, It is getting higher.

An object of the present invention is to provide an epoxy resin composition for a toffee prepreg which is excellent in storage stability, heat resistance, marine property, process stability and drapeability, and is excellent in adhesion between reinforcing fiber and thermosetting resin composition, To provide a resin composition and a toffee containing the same.

According to an embodiment of the present invention, there is provided an epoxy resin composition comprising an epoxy resin and cyanamide, wherein the cyanamide comprises 5 to 20 parts by weight based on 100 parts by weight of the epoxy resin.

Wherein the epoxy resin comprises at least one of a bisphenol A epoxy, a bisphenol F epoxy, a novolac epoxy, a flame retardant epoxy, a cyclic aliphatic epoxy and a rubber-modified epoxy, the epoxy resin having two or more epoxy groups in one molecule, 150 to 340 g / eq equivalent.

The epoxy resin composition may further comprise a curing accelerator.

The curing accelerator may include at least one of a phenol compound, an imidazole compound and a tertiary amine compound.

The curing accelerator may be included in an amount of 5 parts by weight or less based on 100 parts by weight of the epoxy resin.

The glass transition temperature (Tg) of the cured product obtained by heat-treating the epoxy resin composition at 120 ° C for 2 hours by thermal analysis using a differential scanning calorimeter (DSC) is 100 ° C or higher , The tensile strength obtained by the ASTM D638 evaluation is 70 MPa or more, and the elongation may be 2 to 10%.

According to another embodiment of the present invention, the reinforcing fiber is impregnated with an epoxy resin composition, and the epoxy resin composition comprises an epoxy resin and cyanamide, and the cyanamide is added in an amount of 5 to 100 parts by weight, 20 parts by weight.

The reinforcing fibers may include reinforcing fiber bundles composed of 1,000 to 300,000 filaments.

Wherein the reinforcing fiber is selected from the group consisting of a metal fiber, a metalized inorganic fiber, a metalized synthetic fiber, a glass fiber, a polyester fiber, a polyamide fiber, a graphite fiber, a carbon fiber, a ceramic fiber, a mineral fiber, , Kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers and coarse fibers.

The reinforcing fibers may include carbon fibers having a specific gravity of 1.7 to 1.9.

The toffee may have an adhesion of 2 to 30 gf / mm < ² >.

INDUSTRIAL APPLICABILITY As described above, the epoxy resin composition and the toffee containing the epoxy resin composition according to the present invention are excellent in storage stability, heat resistance, marine property, process stability and drapeability, and have excellent adhesiveness between the reinforcing fiber and the thermosetting resin composition And can have a high interlaminar shear strength.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control. Also, although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

First, an epoxy resin composition according to an embodiment of the present invention will be described in detail.

An epoxy resin composition according to an embodiment of the present invention includes an epoxy resin, cyanamide, and a curing accelerator.

The epoxy resin may be a liquid epoxy resin and may include at least one of bisphenol A type epoxy, bisphenol F type epoxy, novolac epoxy, flame retardant epoxy, cyclic aliphatic epoxy and rubber modified epoxy.

Also, the epoxy resin according to the embodiment of the present invention has two or more epoxy groups in one molecule and can be 150 to 340 g / eq equivalent.

When the epoxy resin having an epoxy equivalent of 150 to 340 g / eq and having two or more epoxy groups in one molecule is contained, the viscosity of the final epoxy resin composition can be lowered, and it is easy to handle or impregnate into a bundle of reinforcing fibers, It is also excellent in heat resistance.

The cyanamide may be a liquid cyanamide. As the latent curing agent which is a thermally active latent curing agent, cyanamide is contained in the epoxy resin composition so that stability in the production process of the epoxy resin composition, storage stability at room temperature, Thermal stability in the impregnation step and the like can be ensured.

The epoxy resin composition according to the embodiment of the present invention has excellent adhesiveness and excellent drape property when the epoxy resin composition is impregnated into the reinforcing fiber by incorporating cyanamide to produce a toffee prepreg, And it is also possible to prevent whitening of the surface of the tofrag which may occur when a solid particle type curing agent is used.

The cyanamide may include 5 to 20 parts by weight based on 100 parts by weight of the epoxy resin.

If cyanamide is contained in an amount of less than 5 parts by weight, mechanical strength and heat resistance may be lowered due to a low degree of curing in the preparation of tofres, and if it exceeds 20 parts by weight, the storage stability and drape property to be.

The curing accelerator is for improving the curing activity of the cyanamide, and may include at least one of a phenol compound, an imidazole, and a tertiary amine compound.

The curing accelerator may be included in an amount of 5 parts by weight or less based on 100 parts by weight of the epoxy resin.

This is because if the curing accelerator is contained in an amount exceeding 5 parts by weight, the storage stability may be lowered or the hardness of the cured product may become larger.

The mixed viscosity of the epoxy resin composition according to an embodiment of the present invention may be 10,000 cps or less. When the mixed viscosity of the epoxy resin composition exceeds 10,000 cps, the epoxy resin composition is hardly impregnated sufficiently into the reinforcing fiber This is because the fiber reinforced composite material manufacturing process may cause napping of reinforcing fibers.

When the mixed viscosity of the epoxy resin composition is 10,000 cps or less, the epoxy resin composition can be sufficiently mixed even in a short agitation time, and workability is excellent.

The glass transition temperature (Tg) of the cured product obtained by heat-treating the epoxy resin composition of the present invention at 120 ° C for 2 hours by thermal analysis using a differential scanning calorimeter (DSC) is 100 ° C or higher, and the tensile strength obtained by the ASTM D638 evaluation Is 70 MPa or more, and the elongation may be in the range of 2 to 10%.

This is because when the glass transition temperature (Tg) is 100 占 폚 or more, the fiber-reinforced composite material can be produced with excellent heat resistance while suppressing deterioration of physical properties that may be caused in the fiber-reinforced composite material.

In addition, when the tensile strength is less than 70 MPa, the stress applied to the fiber-reinforced composite material is not sufficiently transferred to the reinforcing fiber, and the physical properties of the fiber-reinforced composite material may be deteriorated.

Next, a description will be made in detail of a toframe comprising an epoxy resin composition according to an embodiment of the present invention.

The tohpre according to an embodiment of the present invention may be formed by impregnating an epoxy resin composition into a bundle of reinforcing fibers having 1,000 to 300,000 filaments.

Here, the epoxy resin composition can use the epoxy resin composition described above, and a duplicate description will be omitted.

If the number of filaments in the bundle of reinforcing fibers is less than 1,000, there is a disadvantage in that the manufacturing cost is increased due to a low area per unit area in manufacturing a large-sized fiber-reinforced composite material. If the number of filaments exceeds 300,000, Tensile strength, compressive strength and the like can be lowered.

The reinforcing fiber is selected from the group consisting of a metal fiber, a metalized inorganic fiber, a metallized synthetic fiber, a glass fiber, a polyester fiber, a polyamide fiber, a graphite fiber, a carbon fiber, a ceramic fiber, a mineral fiber, And may include at least one of kenaf fiber, jute fiber, flax fiber, hemp fiber, cellulose fiber, sisal fiber and coarse fiber, preferably a carbon fiber having a specific gravity of 1.7 to 1.9, And a carbon fiber having a specific gravity of 1.75 to 1.85.

This is because when the specific gravity of the carbon fiber is less than 1.7, voids or the like may be present in the carbon fiber filaments forming the carbon fiber tow, or the compactness of the carbon fiber filament may be lowered so that the compressive strength may be lowered. The effect of lightening can be lowered.

The tofu which is impregnated with the epoxy resin composition in the reinforcing fiber can be produced by various known methods.

For example, a wet method in which an epoxy resin composition is dissolved in an organic solvent such as methyl ethyl ketone or methanol to make a low viscosity, impregnated with a bundle of reinforcing fibers, and then evaporated to an organic solvent using an oven, A filament winding method in which a composition is subjected to a low viscosity by heating without a solvent and then impregnated with a bundle of reinforcing fibers to produce a toffee prepreg; an epoxy resin composition obtained by heating a low viscosity epoxy resin composition on a roll or release paper, And a hot melt method in which the film is transferred to both surfaces and impregnated with a roll so as to be impregnated.

The tread according to an embodiment of the present invention may have a tack of 2 to 30 gf / mm ² .

The tack of the tofread means the tensile stress per unit area generated at the contact surface of the probe and the tofure. When the adhesion is less than ² gf / mm ² , the adhesiveness in the filament winding process is low, , And if it exceeds 30 gf / mm < ^{2 &} gt ;, the tow prep may be defoamed from the bobbin, or the reinforcing fiber fluff may occur during the filament winding process.

The fiber-reinforced composite material that can be produced by laminating the toe prills according to an embodiment of the present invention may have an interlaminar shear strength of 60 MPa or more obtained by the ASTM D2344 evaluation. When the interlaminar shear strength is less than 60 MPa, the reinforcing fiber and the epoxy resin composition The stress applied to the fiber-reinforced composite material can not be sufficiently transferred to the reinforcing fiber, thereby deteriorating the physical properties of the fiber-reinforced composite material.

The toe press according to the embodiment of the present invention can be applied in various fields, and can be used, for example, in the manufacture of pressure vessels.

Here, the pressure vessel may be a cylindrical or non-cylindrical storage tank having a hollow for storing various gases such as hydrogen, methane, butane, propane, helium, nitrogen, oxygen, and the like. The fiber bundle is wound around a liner of a storage tank, and the bundle is cured by applying heat. However, the fiber bundle can be manufactured through various known methods.

Thus, the pressure vessel manufactured using the toe prepress according to the embodiment of the present invention can have a burst pressure of 200 to 2,000 bar on the inspection standard of the Ministry of Land, Transport and Transport No. 2013-562.

Hereinafter, the structure and effect of the present invention will be described in more detail with reference to examples and comparative examples. However, this embodiment is intended to explain the present invention more specifically, and the scope of the present invention is not limited to these embodiments.

Example 1

(1) Preparation of epoxy resin composition

5 parts by weight of liquid cyanamide (AlzChem AG, Dyhard (R) Fluid 111) was added to 100 parts by weight of a bifunctional epoxy resin (Diglycidylether of Bisphenol A, DGEBA: Kumho Pheny Chemical Co., Ltd., KER 828) For 10 minutes to prepare an epoxy resin composition.

(2) Manufacture of toffee

Widely expanded carbon fiber (TORAYCA T700S-24000-50C) 40 parts by weight, the discharge of the carbon fiber tow total weight of the tow at a pressure of 20kgf / cm ³ of the prepared epoxy resin composition, the epoxy resin composition by impregnating the impregnated carbon fiber tows And dried in an oven at 150 DEG C for 2 minutes to prepare a semi-cured toupre.

(3) Manufacture of pressure vessels

The prepared tread was wrapped in a 52L plastic liner using a filament winder, placed in a curing furnace, and cured at 120 ° C for 2 hours to prepare a pressure vessel.

Example 2

A pressure vessel was prepared in the same manner as in Example 1, except that 10 parts by weight of liquid cyanamide was added to 100 parts by weight of the epoxy resin.

Example 3

Except that 10 parts by weight of liquid cyanamide relative to 100 parts by weight of epoxy resin and 5 parts by weight of a curing accelerator (AlzChem AG, Dyhard ^® UR400) relative to 100 parts by weight of epoxy resin were further added A pressure vessel was prepared.

Example 4

A pressure vessel was prepared in the same manner as in Example 1, except that 15 parts by weight of liquid cyanamide was added to 100 parts by weight of the epoxy resin.

Example 5

A pressure vessel was prepared in the same manner as in Example 1, except that 20 parts by weight of liquid cyanamide was added to 100 parts by weight of the epoxy resin.

Comparative Example 1

A pressure vessel was prepared in the same manner as in Example 1, except that 4 parts by weight of liquid cyanamide was added to 100 parts by weight of the epoxy resin.

Comparative Example 2

A pressure vessel was prepared in the same manner as in Example 1, except that 21 parts by weight of liquid cyanamide was contained relative to 100 parts by weight of the epoxy resin.

Comparative Example 3

A pressure vessel was prepared in the same manner as in Example 3, except that 6 parts by weight of a hardening accelerator (AlzChem AG, Dyhard ^® UR400) relative to 100 parts by weight of epoxy resin was used.

Experimental Example

(1) Mixed viscosity measurement of epoxy resin composition

The epoxy resin compositions prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were subjected to measurement of mixed viscosity at room temperature using a viscometer (Brookfield LVDV-I +) at a rotational speed of 3.0 rpm and a No. 62 spindle.

(2) Measurement of glass transition temperature of epoxy resin composition

The epoxy resin compositions prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were cured in an oven at 120 ° C. for 2 hours and cured specimens were heated at a rate of 5 ° C./min using a differential scanning calorimeter (DSC) To measure the glass transition temperature.

(3) Measurement of tensile strength and elongation of epoxy resin composition

The epoxy resin composition prepared in Examples 1 to 5 and Comparative Examples 1 to 3 was injected into a dog-bone mold, cured at 120 ° C for 2 hours, and cured using an Instron Model 5985 UTM according to ASTM D638 The tensile strength was measured. At this time, a load cell having a maximum load of 250 kN was used, and the crosshead speed during the tensile strength test was kept constant at 0.05 mm / min.

(4) Tack measurement of the toffee

The tensile stress at the time when the probe was dropped on the toe prone was measured using a Yeonjin TXA ^TM Texture Analyzer with a compression load of 300 gf and a holding time of 10 seconds using the tread prepared through Examples 1 to 5 and Comparative Examples 1 to 3 , And the tensile stress measured was divided by the area of the probe to measure the adhesiveness of the tofres.

(5) To determine the interlaminar shear strength

The toe progs prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were wound 10 times in a mold and cured at 120 ° C for 2 hours and the interlaminar shear strength was measured using an Instron Model 5965 UTM according to ASTM D2344 standard. At this time, a load cell with a maximum load of 5 kN was used, and the cross head speed was kept constant at 1.0 mm / min during the interlaminar shear strength test.

(6) Measurement of rupture pressure of pressure vessel

The pressure vessel manufactured in Examples 1 to 5 and Comparative Examples 1 to 3 was connected to a pressure vessel by a high pressure water pump in accordance with Ministry of Land Transport and Public Notice Notice No. 2013-562 to raise the pressure inside the pressure vessel, The rupture pressure of the pressure vessel was measured.

The results are shown in Table 1 below.

Mixed viscosity
(cps) Tg
(° C) The tensile strength
(MPa) Elongation
(%) Adhesiveness
(gf / mm ² ) Interlayer shear
Strength (MPa) Burst pressure
(bar) Example 1 9700 102 71 9.8 2.64 61 319 Example 2 6600 118 78 6.7 10.48 72 762 Example 3 3800 129 85 4.4 22.44 81 1469 Example 4 3600 126 83 4.2 20.12 81 1492 Example 5 940 135 92 2.3 28.73 93 1886 Comparative Example 1 10500 98 65 10.1 1.96 55 193 Comparative Example 2 900 138 93 1.8 32.36 94 1612 Comparative Example 3 11000 139 90 1.6 35.21 89 1247

As shown in Table 1, as the cyanamide content increases, the glass transition temperature and the tensile strength increase but the elongation decreases. This is because it limits the mobility of the epoxy resin molecules as the cyanamide content increases.

As the cyanamide content increases, the adhesion of the tofuram and the interlaminar shear strength also increase. This is because the crosslinking degree of the epoxy resin composition impregnated into the reinforcing fiber in the semi-cured state increases as the cyanamide content increases, And increased shear strength.

On the other hand, in Comparative Example 1 in which the cyanamide content is less than 5 parts by weight, the mixing viscosity is too high, the glass transition temperature is less than 100 ° C, the tensile strength is less than 70 MPa, the elongation is also excessively high, Comparative Example 2 in which the cyanamide content exceeded 20 parts by weight was too low in elongation and too high in adhesiveness to cause napping and was incompatible. Comparative Example 2, which contained curing accelerator in an amount of more than 5 parts by weight In Example 3, it was confirmed that the mixed viscosity was too high, the elongation was too low, and the adhesiveness was excessively high, so that fluff was formed.

INDUSTRIAL APPLICABILITY As described above, the epoxy resin composition and the toffee containing the epoxy resin composition according to the present invention are excellent in storage stability, heat resistance, marine property, process stability and drapeability, and have excellent adhesiveness between the reinforcing fiber and the thermosetting resin composition And can have a high interlaminar shear strength.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (12)

delete delete delete delete delete delete As a toffee prepreg impregnated with an epoxy resin composition in a reinforcing fiber,
Wherein the epoxy resin composition comprises an epoxy resin and a liquid cyanamide, wherein the liquid cyanamide includes 5 to 20 parts by weight based on 100 parts by weight of the epoxy resin,
Toupee with an adhesion of 2 to 30 gf / mm ² . 8. The method of claim 7,
Wherein the epoxy resin composition comprises 5 parts by weight or less of a curing accelerator containing at least one of a phenol compound, an imidazole, and a tertiary amine compound, based on 100 parts by weight of the epoxy resin. 8. The method of claim 7,
Wherein the reinforcing fiber comprises a bundle of reinforcing fibers consisting of 1,000 to 300,000 filaments. The method of claim 9,
Wherein the reinforcing fiber is selected from the group consisting of a metal fiber, a metalized inorganic fiber, a metalized synthetic fiber, a glass fiber, a polyester fiber, a polyamide fiber, a graphite fiber, a carbon fiber, a ceramic fiber, a mineral fiber, , Kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers and coir fibers. 11. The method of claim 10,
Wherein the reinforcing fiber comprises a carbon fiber having a specific gravity of 1.7 to 1.9. delete