JP2002179771A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition useful as a matrix resin for impregnating prepreg, having appropriate fluidity to the extent not to affect the characteristic of the prepreg to obtain uniform adhesion over whole adhering interface of a honeycomb core, excellent in self-adhesion with the honeycomb core. SOLUTION: This epoxy resin composition comprises an epoxy resin, an aromatic amine-based curing agent, and a solid rubber compatible with the epoxy resin and is characterized in that a minimum value η0,02 of complex viscosity measured at 0.02 Hz of vibrating frequency at 50 to 150 deg.C exists in a range of 1.0 to 200 Pa.s, and a temperature Tlow in the low temperature side where the complex viscosity becomes 1,000 Pa.s in the course of curing of the resin composition and a temperature Thigh in the high temperature side where the complex viscosity becomes 1,000 Pa.s satisfy the relation 80 deg.C<=Thigh-Tlow<=150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a prepreg having excellent fillet formation, excellent adhesiveness with a honeycomb core material, uniform adhesive strength over the entire honeycomb core adhesive surface, and excellent heat resistance. The present invention relates to an epoxy resin composition useful as a matrix resin for impregnation.

[0002]

2. Description of the Related Art Epoxy resin compositions are used as resins having excellent heat resistance in fields such as construction, civil engineering, automobiles and aircraft. A fiber-reinforced composite material using an epoxy resin composition as a matrix resin has excellent mechanical properties, heat resistance, and water resistance. So far, prepregs using a combination of epoxy resins having various compositions and reinforcing fibers have been proposed. . A prepreg is generally in the form of a sheet, and includes a sheet plane in which continuous fibers are arranged in parallel in one direction, a continuous fiber fabric, a sheet in which discontinuous fibers are arranged in an arbitrary direction, and the like. is there. A prepreg used for an aircraft structural material or the like is often formed into a structure in which a flat surface of a prepreg is joined to a cross section of a honeycomb having a honeycomb structure from the viewpoint of weight reduction of the structural material. Conventionally,
In order to obtain the adhesion between the honeycomb core material and the prepreg, a sheet-like adhesive is bonded between the honeycomb core material and the prepreg.

[0003] A so-called cocure or self-adhesive molding is required for a prepreg, in which a prepreg is laminated on both surfaces of a honeycomb core without interposing an adhesive sheet, and curing of the prepreg itself and adhesion to the honeycomb are performed simultaneously and without an adhesive. Have been. In particular, if the prepreg and the honeycomb can be bonded without sandwiching the adhesive sheet between the prepreg and the honeycomb, the manufacturing process can be shortened, which is desirable.

As an epoxy resin for impregnating a prepreg having a self-adhesive property, various inventions have been disclosed which regulate the viscosity characteristics of the resin. JP-A-5-239317 discloses an epoxy resin composition comprising an epoxy resin, a curing agent, and a solid rubber for the purpose of avoiding generation of porosity (voids and voids generated during curing of the resin). A vibration frequency of 0.02H at 80 ° C.
The complex viscosity η _0.02 measured at z is 500 Pa · s or more, and the complex viscosity η ₂ and η measured at a vibration frequency of 2 Hz.
Epoxy resin compositions are disclosed _{which 0.02} relationship satisfies logη _0.02 -logη ₂ ≧ 0.5.

Japanese Patent Application Laid-Open No. 9-194611 discloses that a reinforcing fiber and a matrix resin are used for the purpose of improving tackiness and drapability, the matrix resin is a thermosetting resin, and the measurement frequency is 0.5 Hz. Complex viscosity η ^{* of the} matrix resin in dynamic viscoelasticity measurement at 50 ° C.
In the range of 200 to 2000 Pa · s and the energy loss tan δ in the range of 0.3 to 5 are disclosed.

On the other hand, from the viewpoint of producing a resin film suitable for producing a prepreg in which the resin content of the prepreg is uniform and uniform, JP-A-11-254435 discloses that the minimum viscosity is 0.01 to 30 Pa · s. A resin film for producing a prepreg formed by applying a thermosetting resin on a release sheet is disclosed. According to the present invention, if the minimum viscosity is lower than 0.01 Pa · s, the resin film cannot be produced uniformly, causing a problem of causing flow or repelling. If it exceeds 30 Pa · s, the film is not evenly produced, and when transferring the resin from the coating roll to the release paper, a uniform resin film cannot be obtained due to transfer unevenness, and the prepreg produced It is described that good molded products cannot be obtained due to insufficient tack and drape.

The above prior arts are all aimed at improving the thixotropy of the resin and the coating property on the release paper. Until now, the fillet formed by the resin when the honeycomb and the prepreg are bonded to each other has been proposed. No description is given of the relationship between the formability, fillet formation and the complex viscosity of the resin, and the conditions for obtaining good fillet formation are not disclosed.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to obtain a uniform adhesive force over the entire bonding surface between a honeycomb and a prepreg, so as to have an appropriate fluidity within a range not impairing the properties of the prepreg. An object of the present invention is to provide an epoxy resin composition having excellent self-adhesiveness to a core material and useful as a matrix resin for prepreg impregnation.

Here, FIGS. 1 and 2 show an example of a structure in which a prepreg and a honeycomb are bonded, and a method of bonding the prepreg to the honeycomb and a fillet will be described. Here, the fillet indicates a shape of a resin layer formed between the prepreg and the honeycomb when the prepreg and the honeycomb are joined and cured.

FIG. 1 is a perspective view of the structure 1. FIG.
FIG. 2 is a cross-sectional view of the structure 1 cut in parallel with a side surface of a prism of the honeycomb 11. FIG. 2A shows a structure in which a fillet is not properly formed, and FIG. 2B shows fillets 14, 1 and 2.
4 'indicates a properly formed structure.

As shown in part a of FIG. 2, when a conventional epoxy resin composition for a prepreg is used, when it is cured by heating,
Even if the prepreg 10 and the honeycomb 11 are pressed evenly,
All of the epoxy resin composition may fall on the lower surface portion 13 ′ and no fillet is formed on the upper surface portion 13, or a gap may be partially formed on the bonding surface between the prepreg 10 and the honeycomb 11. For this reason, the adhesion between the honeycomb and the prepreg becomes incomplete.

On the other hand, as shown in part b of FIG. 2, appropriate fillets 14, 14 'are formed on the bonding surface between the prepreg 10 and the honeycomb 11, and the fillet 1 is formed.
If the curing can be completed while properly maintaining the shapes of the prepreg 10 and the honeycomb 11, the prepreg 10 and the honeycomb 11 can be firmly bonded without forming a gap in the bonding surface between the prepreg 10 and the honeycomb 11. . in this way,
In order for epoxy resin for prepreg impregnation to have self-adhesiveness, it is important that the resin has good fillet-forming properties.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the development of self-adhesiveness of an epoxy resin for impregnating a prepreg, and as a result, it has been found that a fillet is formed on an end face where a honeycomb and a prepreg are joined. In order to form a fillet, it is necessary to give the resin an appropriate flow property, and to control the flow property, the minimum viscosity of the resin and the temperature range below the viscosity that includes the minimum viscosity and allows the resin to flow Control is important, and an epoxy resin composition containing an epoxy resin, an aromatic amine-based curing agent, and a solid rubber compatible with the epoxy resin achieves the above-described properties. And found that the present invention was completed.

That is, the present invention relates to an epoxy resin composition containing an epoxy resin, an aromatic amine-based curing agent, and a solid rubber compatible with the epoxy resin.
The lowest value (minimum complex viscosity) η _{0.02 of} the complex viscosity measured at a vibration frequency of 0.02 Hz at 0 ° C. is 1.0 to 20.
The low-temperature side T _low at which the resin composition is present in the range of 0 Pa · s and the complex viscosity gives 1000 Pa · s during curing of the resin composition, and the _high- temperature temperature T _{high at} which 1000 Pa · s is given, And an epoxy resin composition satisfying the relationship of 80 ° C. ≦ T _high −T _low ≦ 150 ° C.

The epoxy resin includes an epoxy resin having an N-glycidylamino group, and further includes a bifunctional or higher functional epoxy resin, and at least one of the bifunctional or higher functional epoxy resin has a naphthalene ring, a dicyclopentadiene group. , A bisphenyl group, and a fluorene group.

Preferably, the aromatic amine curing agent is an aromatic amine compound having one or more amino groups.

Preferably, the solid rubber is an acrylonitrile butadiene rubber (NBR) compatible with the epoxy resin at a temperature of 20 to 150 ° C.

At least one of the epoxy resins having two or more functional groups is (a) an epoxy resin having a dicyclopentadiene group, and the epoxy resin having an N-glycidylamino group is (b) having an glycidylamino group. Aromatic epoxy resin, aromatic amine-based curing agent,
(C) diaminodiphenylsulfone, wherein (a) an epoxy resin having a dicyclopentadiene group is at least 15% by weight and (b) an aromatic epoxy resin having a glycidylamino group is 50% by weight of all epoxy resins. %
And the total amount of (a) and (b) is preferably 65 to 95% by weight. The composition of the present invention is an epoxy resin composition for prepreg impregnation and can be used as an adhesive for bonding a prepreg and a honeycomb core.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy resin composition of the present invention (hereinafter, referred to as the composition of the present invention) contains an epoxy resin, an aromatic diamine-based curing agent, and a solid rubber compatible with the epoxy resin, and has a vibration frequency at 50 to 150 ° C. Lowest value of complex viscosity measured at 0.02 Hz (lowest complex viscosity) η _0.02
Is 1.0 Pa · s ≦ η _0.02 ≦ 200 Pa · s, and the complex viscosity is 1000 P during curing of the resin composition.
The temperature T _low on the low temperature side that gives a · s, and 1000
The temperature T _high on the high temperature side that gives Pa · s is 80 ° C. ≦ T
It is a composition having physical properties satisfying the relationship of _high- T _low ≦ 150 ° C.

In the present invention, the complex viscosity is defined as a dynamic mechanical analyzer (dynamic viscoelasticity measuring device; D
MA) and the value measured as follows.

That is, the gap between the plates is set to 1.0 mm by a plate-plate type (parallel plate method) measurement using a disk-shaped plate having a diameter of 25 mm or 50 mm. The plate of the present invention is filled between the two plates, and one plate is set at a predetermined frequency with an amplitude of 3.0.
Give% vibration. The complex viscosity is obtained from the torque and the phase difference generated at that time. The minimum complex viscosity η _0.02 at a vibration frequency of _0.02 Hz at 50 to 150 ° C. is obtained by raising the temperature of the measurement atmosphere from 50 ° C. to 150 ° C. at a rate of 2 ° C./min. Is vibrated, the complex viscosity is obtained from the torque and the phase difference generated at that time, and the minimum value is obtained from the obtained complex viscosity.

FIG. 3 shows the relationship between the complex viscosity at a vibration frequency of 0.02 Hz and the measured temperature when three types of epoxy resin compositions having different complex viscosities are heated at a constant speed to 50 to 150 ° C. 4 shows a schematic graph representing. The vertical axis of the graph is the complex viscosity, and the horizontal axis is the measured temperature. In the graph,
Passing through a point on the vertical axis where the complex viscosity is 1000 Pa · s,
The intersection of the straight line parallel to the horizontal axis and the curve is T _{low on the low} temperature side and T _high on the _high temperature side in the same curve. The value of the complex viscosity of 1,000 Pa · s is a complex viscosity that is a measure of the flowability of the epoxy resin composition of the present invention and is 1
The composition of the present invention exhibits fluidity in the region of a complex viscosity lower than 000 Pa · s. Hereinafter, the relationship between the fillet forming property, the complex viscosity, and the temperature difference between T _low and T _high will be qualitatively described. Note that a region including the lowest complex viscosity, a temperature width lower than a certain complex viscosity, and a region surrounded by 1000 Pa · s and the lowest complex viscosity is referred to as a “process window”.
That.

The epoxy resin giving a curve giving the complex viscosity-measurement temperature of the above has a relatively high minimum complex viscosity η _0.02 and a temperature difference between T _low and T _high (T _low -T _high ).
However, it is larger than other epoxy resins. Since the measurement temperature is raised at a constant speed, a large temperature range can be considered as a long time between them. Such an epoxy resin has a wide temperature range in which the resin can flow with low viscosity, but since the resin has low fluidity in the vicinity of a temperature at which η _0.02 is given, it is difficult for the resin to flow from the prepreg to the honeycomb, and it takes time to form a fillet. It takes too much and eventually has poor fillet formation.

The epoxy resin giving the curve of
Complex viscosity η_0.02Is relatively low and T _low-T_highBut other
Epoxy resin, smaller than that. Such an d
Poxy resin is η_0.02Near the temperature that gives
High enough, but T_low-T_{hi gh}Is epoxy resin,
The time required for the resin to flow with low viscosity is relatively small
Short, fillet formation not complete, fillet formation
Inferior.

The epoxy resin giving the curve is a resin having physical properties between the epoxy resin and the epoxy resin. The minimum complex viscosity η _0.02 is not so low, T _low −T
_high is not that small. Such an epoxy resin has a certain degree of fluidity of the resin and a temperature range at which the resin can flow with a low viscosity. Therefore, when a prepreg using such a resin as an epoxy resin for impregnation is honeycomb-bonded, an appropriate fillet is obtained. Is formed, and the prepreg and the honeycomb are sufficiently firmly bonded to each other.

In general, in a structure obtained from a honeycomb and a prepreg, which is required to have a high adhesive force, such as for an aircraft,
Adhesion between the prepreg and the honeycomb is achieved at a heating rate of about 2 ° C
The temperature is raised to a predetermined curing temperature at a pressure of about 3 kg / cm ² per minute, and then the temperature is maintained for a predetermined time. Therefore, the curing temperature of the resin is set near this predetermined curing temperature so that the prepreg-impregnating resin is sufficiently cured under these elevated temperature conditions, and the temperature at which the fillet is formed is also preferably around this predetermined curing temperature. . Therefore, the temperature range in which the resin exhibits fluidity is a temperature range lower than the predetermined curing temperature. The curing temperature is not constant, and may be appropriately set depending on various uses.

The composition of the present invention has a minimum complex viscosity η measured at a vibration frequency of 0.02 Hz at 50 to 150 ° C.
_0.02 is 1.0 Pa · s ≦ η _0.02 ≦ 200 Pa · s. The composition of the present invention has a η in a temperature range of 50 to 150 ° C.
_{Since 0.02} ≦ 200 Pa · s, the composition can sufficiently flow out of the prepreg before the composition is cured to form a fillet, and the honeycomb and the prepreg can be firmly bonded. . On the other hand, since 1.0 Pa · s ≦ η _0.02 , the composition does not flow out of the prepreg too much, and does not impair the properties of the prepreg such as adhesiveness and cured product strength. Preferably, 2.0 Pa · s ≦ η _0.02 ≦ 180 Pa
-It is s.

The composition of the present invention has a complex viscosity of 1000
At Pa · s, 80 ° C ≦ T _high −T _low ≦ 150 ° C.
Satisfy the relationship. If the temperature range is within this range, sufficient time is allowed for the composition to flow and form a fillet, and the composition flows out of the prepreg too much, and the properties of the prepreg, such as adhesiveness and cured product strength, are reduced. There is no loss. Preferably, 82 ° C. ≦ T _high −T _low ≦ 14
8 ° C.

The length of the fillet formed between the honeycomb and the prepreg is preferably 100 μm or more. This is because if the fillet is 100 μm or more, strong adhesiveness can be obtained between the honeycomb and the prepreg. More preferably, it is 110 μm or more.
The appropriate length of the fillet was determined as follows. A carbon prepreg obtained by impregnating a carbon fiber sheet with an epoxy resin composition is joined to both cross sections of a Nomex honeycomb made of an aramid-based resin exhibiting a honeycomb pattern, and the temperature is increased by an autoclave at a rate of 2 ° C./min and a pressure of 3 kg.
The temperature is raised to 180 ° C./cm ² and then kept at that temperature for 120 minutes. A tensile test is performed using the obtained structure of the honeycomb and the prepreg, and the adhesive strength between the honeycomb and the prepreg is measured. In addition, in the same structure, it is observed how long the fillets are formed above and below both ends of the honeycomb, and whether the honeycomb and the prepreg are joined without gaps. This makes it possible to know the length of the fillet when sufficient adhesive strength is obtained.

The composition of the present invention satisfying the above-mentioned physical properties is an epoxy resin composition containing an epoxy resin, an aromatic amine-based curing agent, and a solid rubber compatible with the epoxy resin. The epoxy resin used in the present invention is not particularly limited as long as it is a polyepoxy compound having an average of two or more epoxy groups in one molecule. Specific examples include, for example, epoxy compounds having a bisphenyl group such as bisphenol A type, bisphenol F type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol S type, bisphenol AF type, and biphenyl type; Bifunctional glycidyl ether epoxy resins such as an alkylene glycol type, an alkylene glycol type epoxy compound, an epoxy compound having a naphthalene ring and an epoxy compound having a fluorene group; phenol novolak type, orthocresol novolak type, DPP
Novolak type, Tris-hydroxyphenylmethane type,
Polyfunctional glycidyl ether type epoxy resin such as trifunctional type and tetraphenylolethane type; glycidyl ester type epoxy resin of synthetic fatty acid such as dimer acid; N, N, N ′, represented by the following formula (1): Epoxy resin having an N-glycidylamino group such as N′-tetraglycidyldiaminodiphenylmethane (TGDDM), tetraglycidyl-m-xylylenediamine, triglycidyl-p-aminophenol, N, N-diglycidylaniline;

[0031]

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The tricyclo [5, represented by the following formula (2)
2,1,0 ^2,6 ] epoxy compound having a decane ring (hereinafter referred to as dicyclopentadiene group), specifically, for example, polymerization of dicyclopentadiene and cresols such as metacresol, or phenols After letting
An epoxy compound obtainable by a known production method of reacting epichlorohydrin;

[0033]

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Alicyclic epoxy resin; epoxy resin represented by FLEP 10 manufactured by Toraythiol Co., Ltd .; epoxy resin having a sulfur atom in the main chain; urethane-modified epoxy resin having urethane bond; polybutadiene, liquid polyacrylonitrile-butadiene rubber or A rubber-modified epoxy resin containing NBR is exemplified. These may be used alone or in combination of two or more.

The composition of the present invention preferably contains an epoxy resin having an N-glycidylamino group as an essential component. By including the epoxy resin having an N-glycidylamino group, the composition of the present invention can have excellent heat resistance and water resistance. As the epoxy resin having an N-glycidylamino group, commercially available products can be used. For example, ELM-434, manufactured by Sumitomo Chemical Co., Ltd.
TETRAD-X manufactured by Mitsubishi Gas Chemical Company or the like can be used.

The composition of the present invention comprises, as an epoxy resin,
In addition to the above-mentioned epoxy resin having an N-glycidylamino group, the epoxy resin preferably further contains an epoxy resin having two or more epoxy groups in one molecule, and at least one of the bifunctional or more epoxy resin has a naphthalene ring, It preferably has at least one functional group selected from the group consisting of a dicyclopentadiene group, a bisphenyl group, and a fluorene group. By containing these bifunctional or higher epoxy resins, the composition of the present invention
It is preferable because it has excellent heat resistance, water resistance, and good adhesion to honeycomb and carbon fiber.

The aromatic amine curing agent used in the present invention is:
The aromatic amines used as an epoxy resin curing agent are not particularly limited as long as they are aromatic amines. Specifically, diaminodiphenyl sulfone (D) represented by the following formula (3)
DS), diaminodiphenylmethane (DDM), diaminodiphenylether (DADPE), bisaniline,
Benzyldimethylaniline, 2- (dimethylaminomethyl) phenol (DMP-10), 2,4,6-tris (dimethylaminomethyl) phenol (DMP-3)
0) and tri-2-ethylhexyl acid salt of DMP-30. These can be used alone or 2
Mixtures of more than one species may be used.

[0038]

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Among the above-described aromatic amine-based curing agents, aromatic amine-based compounds having one or more amino groups in the molecule are preferred from the viewpoint that the resulting composition of the present invention has excellent heat resistance. Examples of such an aromatic amine compound having one or more amino groups include diaminodiphenylsulfone (DDS) and diaminodiphenylmethane (DDS).
DM), diaminodiphenyl ether (DADPE),
Bisaniline and the like can be mentioned. Among these, it is preferable to use various isomers of diaminodiphenylsulfone (DDS) as a curing agent because they are particularly excellent in heat resistance.

The content of the aromatic amine-based curing agent is not particularly limited, but from the viewpoint of exhibiting heat resistance, the equivalent ratio to the epoxy resin is determined by the following formula. The equivalent weight is preferably 0.6 to 1.2, and more preferably 0.7 to 1.1.

In the composition of the present invention, in addition to aromatic amine-based curing agents, those generally used as curing agents for epoxy resins and curing catalysts, as long as the object of the present invention is not impaired. You may mix. For example, dicyandiamide (DICY), various derivatives of imidazole, aminobenzoic acid esters, various acid anhydrides, phenol novolak resins, cresol novolak resins and the like can be mentioned.

The solid rubber compatible with the epoxy resin used in the present invention is a solid rubber having a functional group capable of reacting with the epoxy resin in a molecule and compatible with the epoxy resin at preferably 20 to 150 ° C. is there. As the rubber, acrylonitrile butadiene rubber and its hydride, acrylic rubber, ethylene-acryl rubber, styrene-butadiene rubber, epichlorohydrin rubber, butyl rubber, ethylene-
Various rubbers having excellent heat resistance such as propylene rubber and ethylene-vinyl acetate rubber are exemplified. Examples of the functional group include a carboxyl group, a halogen group, and maleic acid.

Among them, the carboxy-modified acrylonitrile-butadiene rubber is particularly preferably the above-mentioned preferred epoxy resin, specifically, the epoxy resin having an N-glycidylamino group, and further containing the epoxy resin having two or more functional groups. At least one of the above epoxy resins is preferable because it has good compatibility with an epoxy resin having at least one functional group selected from the group consisting of a naphthalene ring, a dicyclopentadiene group, a bisphenyl group, and a fluorene group. . As the acrylonitrile butadiene rubber, one or both of hydrogenated and non-hydrogenated rubbers may be used. When a hydrogenated product is used, the obtained composition of the present invention has good weather resistance and heat resistance. The acrylonitrile-butadiene rubber may be one of various compositions or a mixture of two or more. Further, the hydrogenated acrylonitrile butadiene rubber has a nitrile content of 20% by weight to 40% by weight and a carboxy content of 0.5% by weight.
Carboxy-modified hydrogenated acrylonitrile butadiene rubber having a content of about 6% by weight is preferred from the viewpoint of compatibility.

The content of the solid rubber compatible with the epoxy resin is not particularly limited, but is preferably 5 to 19 parts by weight based on 100 parts by weight of the epoxy resin. Is preferable from the viewpoint of the viscosity (complex viscosity) and the fillet forming property.

As the composition of the present invention, (a) an epoxy resin having a dicyclopentadiene group, (b) an aromatic epoxy resin having a glycidylamino group, and
(C) containing diaminodiphenylsulfone, and
In all the epoxy resins, the epoxy resin (a) is 15% by weight or more, and (b) the aromatic epoxy resin having a glycidylamino group is 50% by weight or more, and
More preferably, the total amount of (a) and (b) is 65 to 95% by weight. When it is 65% by weight or more, it is more preferable from the viewpoint of water resistance and heat resistance, and when it is 95% by weight or less, it is more preferable from the viewpoint of workability.

As the epoxy resin having a dicyclopentadiene group, commercially available products can be used. Examples thereof include TACTIX-556 manufactured by Dow Chemical Company and HP-7200 manufactured by Dainippon Ink and Chemicals. I can do it.

In the composition containing the epoxy resin (a) and the epoxy resin (b) in the above range as the epoxy resin contained in the composition of the present invention, two or more epoxy groups are averaged in one molecule. It is preferable to contain 5-35 weight of the general-purpose epoxy resin used in the general epoxy resin composition described above as the polyepoxy compound to maintain heat resistance and control tackiness and drapability.
Commercial products can also be used as such an epoxy resin, and examples thereof include glycidyl ether type epoxy resins represented by the following formulas (4) and (5). A specific example is TACTIX-7 manufactured by Dow Chemical Company.
42 (trifunctional epoxy resin), EP-154 (phenol novolak epoxy resin) manufactured by Yuka Shell Chemical Co., Ltd.
It is possible to use commercially available products such as.

[0048]

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The solid rubber compounded in the composition of the present invention having the above specific composition is not particularly limited, and any of the solid rubbers described above can be compounded. Among them, a combination with a carboxy-modified acrylonitrile butadiene rubber can be used. Is preferred from the viewpoints of heat resistance, viscosity, and fillet forming property of the obtained composition of the present invention.

The composition of the present invention comprises, in addition to the components described above,
Other additives such as a filler, an antioxidant, a solvent and the like may be blended within a range not to impair the object of the present invention.

Examples of the filler include carbon black, calcium carbonate, titanium oxide, silica, and aluminum hydroxide. Examples of the anti-aging agent include hindered amines and hindered phenols. Examples of the solvent include methanol, ethanol, propanol, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK) and the like.

The composition of the present invention comprises an epoxy resin, an aromatic amine curing agent, a solid rubber compatible with the epoxy resin,
Further, if necessary, a raw material such as a filler is mixed together using a Dalton-type mixer, a paint roll, a grinder, or the like by an ordinary method. In particular, when (hydrogenated) acrylonitrile butadiene rubber is mixed, it may be dissolved in a solvent and mixed, or may be mixed with a kneader, roll, paint roll, or the like. It must be dissolved.

Since the epoxy resin composition of the present invention can form a good fillet by adopting the above-mentioned constitution, it exhibits excellent adhesive strength. Furthermore, it has excellent heat resistance. Therefore, the epoxy resin composition of the present invention is useful as an adhesive, a matrix resin composition for prepreg, and the like.

An example of manufacturing a structure with a honeycomb using the composition of the present invention as a matrix resin composition for prepreg will be described below. Prepreg is made of carbon fiber,
Aramid fiber such as Kevlar, fiber woven fabric such as glass fiber,
Alternatively, it is produced by impregnating the unidirectional fiber with the epoxy resin composition of the present invention or laminating a plurality of woven fabrics impregnated with resin. When impregnating, either a wet method using a solvent or a hot melt method that is a solventless method may be used. In the case of producing a prepreg by a wet method, the composition of the present invention is dissolved in a solvent, a varnish is prepared, and the varnish is impregnated. As a solvent used at the time of preparing the varnish, alcohols such as methanol, ethanol and propanol, or ketones such as methyl ethyl ketone (MEK) are preferable. A varnish containing the composition of the present invention dissolved in these solvents is preferably used. After adjustment, the woven fabric may be impregnated. When the amount of the solvent added is such that the composition 10
The amount of 1 to 20 parts by weight relative to 0 parts by weight is preferable for optimizing the drying step.

The fiber woven fabric used for the prepreg using the composition of the present invention as a matrix resin includes carbon fiber, aramid fiber such as Kevlar, fiber woven fabric such as glass fiber, and unidirectional fiber (long fiber) thereof. Is mentioned. As a specific example, a carbon fiber T-30 manufactured by Toray Industries, Inc.
And carbon fiber HTA grade manufactured by Toho Rayon Co., Ltd., and the fiber basis weight is preferably 140 to 200 g / m ² . The prepreg using the composition of the present invention as a matrix resin is preferably a prepreg obtained by impregnating a woven fabric of carbon fibers as a varnish with or without a solvent using the composition of the present invention. Such a prepreg can be manufactured using a device such as a UD (unidirectional) machine. The weight of the reinforcing material varies greatly depending on the fiber material and woven structure. Therefore, the content of the impregnated composition may be a value suitable for each use, and is not particularly limited.

The composition of the present invention is not only a matrix resin of the prepreg but also an adhesive with the honeycomb. Therefore, if the prepreg is applied as it is, it is not necessary to use another adhesive between the prepreg and the honeycomb. Therefore,
It is not necessary to use an adhesive sheet for bonding the honeycomb and the prepreg, and the manufacture of the structure of the honeycomb and the prepreg becomes easy. Also, the use of auxiliary materials such as sheets and release paper can be reduced, contributing to global environmental conservation. Of course, the composition of the present invention can be used only for prepreg impregnation or as an adhesive between honeycomb and prepreg.

As the material of the honeycomb, any composition may be used as long as it is a non-metallic honeycomb such as resin-based or paper. For example, a Nomex honeycomb in which Nomex is impregnated with a phenol resin is an aircraft. It is most preferable when considering the application to Various sizes can be used for the size of the hexagonal pillars of the honeycomb-shaped structure of the honeycomb, but the honeycomb cell having a length of 1/8 to 3/8 inch is used. It is preferable in terms of weight reduction.

The fact that the composition of the present invention is not only a matrix resin of the prepreg but also can be used as an adhesive with the honeycomb. The fact that the prepreg is prepared using the composition of the present invention, and the prepreg itself is cured and adhered to the honeycomb. This means that so-called cocure molding can be performed simultaneously. Examples of the bonding method include a method in which a prepreg impregnated with the composition of the present invention is bonded to one or both end faces of a honeycomb showing a honeycomb structure, and heat-cured by an autoclave or the like while applying pressure from both ends. You. Curing conditions for bonding the honeycomb and the prepreg are 2 to 5 ° C. (preferably 2 ° C.) / Min, and pressure 2.5 to 5 ° C.
At 4.0 (preferably 3) kg / cm ² , 150-18
After raising the temperature to 5 ° C (preferably 180 ° C),
Maintain at １８185 ° C. (preferably 180 ° C.) for 1-2 hours (preferably 2 hours), and then maintain at 2-5 ° C. (preferably 2 hours).
(° C.) / Min to room temperature.

In the thus obtained prepreg / honeycomb structure using the composition of the present invention as a prepreg impregnating resin, the composition of the present invention has an appropriate complex viscosity, and A fillet is formed. For this reason, conventionally, the bonding between the honeycomb and the prepreg was incomplete, but in the composition of the present invention, the bonding was completely performed,
Uniform adhesive strength is obtained over the entire adhesive surface. In addition, since the epoxy resin composition does not flow out of the prepreg excessively and an appropriate amount of the epoxy resin composition can be present in the prepreg, curing can be completed while maintaining an appropriate shape of the fillet. In addition, also on the lower surface of the structure, when the viscosity once decreases, a fillet is formed by surface tension, the composition is appropriately held, and curing can be completed. Furthermore, since the epoxy resin composition can be present in the prepreg in an appropriate amount without flowing out too much, the characteristics of the prepreg are not impaired.

The thus obtained structure of the prepreg and the honeycomb using the composition of the present invention has excellent heat resistance and sufficient adhesion between the prepreg and the honeycomb. It is useful as a member.

[0061]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples of the present invention. (Examples 1 to 3 and Comparative Examples 1 to 6) Various epoxy resin compositions were produced at the weight ratios shown in Table 1 below by sufficiently stirring the components or partially using a paint roll. . The following evaluation was performed about the obtained epoxy resin composition. The results are shown in Table 1 below. The amount of the epoxy resin was shown by weight% of the total epoxy resin, and the amount of the rubber and the amount of the curing agent were shown by parts by weight based on 100 parts by weight of the epoxy resin.

<Viscoelasticity>
Nikal Analyzer (Dynamic Viscoelasticity Measurement Device; DMA)
Using the parallel plate method (diameter 25mm)
Measured at a heating rate of 2 ° C./min and a frequency of 0.02 Hz, the composition
Complex viscosity η in the curing process of the product _0.02[Pa ・
s] was measured. <Temperature range where the complex viscosity is less than 1000 Pa · s> <Viscosity
Elasticity> The same measurement method as in the test
And the temperature on the low temperature side at which each composition shows 1000 Pa · s
T_lowAnd the higher temperature T_highIs measured and the complex viscosity is
A temperature range [° C.] lower than 1000 Pa · s was determined.

<Flowability of Resin> Carbon fiber (T-300, manufactured by Toray Industries, Inc.) using a UD machine manufactured by Yokohama Rubber Co., Ltd.
(A fiber weight of 190 g / m ² ) was impregnated with 38% of a composition having the composition shown in Table 1 below to prepare a carbon prepreg.
Using this carbon prepreg, a structure is manufactured by laminating with a honeycomb core, and under the curing conditions for bonding the honeycomb and the prepreg, the flowability of the composition is visually evaluated, and the flow of the composition is evaluated. Those having no problem with fillet formation due to the property were defined as “good”, those that formed a fillet but did not have sufficient adhesion were rated as “OK”, and those that had excessively flowed out of the prepreg were determined as “excessive”. The composition which did not flow was evaluated as "not flowing". <Adhesiveness> Using a structure of the honeycomb and the carbon prepreg, a specimen in which the honeycomb and the prepreg were fixed to a jig was subjected to a tensile tester in accordance with a flatwise tensile test described in MIL-STD-4018. It is fixed and pulled at a pulling speed of 0.5 mm / min, and the maximum load until the structure is broken is measured. Here, the flat wise tensile strength F [MPa] is obtained by the following equation. F = P _MAX / (a × b) Here, F: flatwise tensile strength [MPa] P _MAX : maximum load [N] a, b: width of test specimen [m] The adhesive strength is 4.13. [MPa] or more is preferable.

[0064]

[Table 1]

<Each component in the table> ELM-434: glycidylamine type epoxy resin (epoxy equivalent: 120), HP-7200 manufactured by Sumitomo Chemical Co., Ltd .: epoxy resin having dicyclopentadiene group (epoxy equivalent: 250 to 280), large TACTIX-742: Triphenylmethane triglycidyl ether (epoxy equivalent: 160) manufactured by Nippon Ink and Chemicals, EP-154: Phenol novolak type epoxy resin (epoxy equivalent: 180) manufactured by Dow Chemical Company, Nipol manufactured by Yuka Shell Chemical 1072: Carboxy-modified acrylonitrile butadiene rubber, manufactured by Zeon Corporation DDS: 4,4'-diaminodiphenyl sulfone (molecular weight: 248), trade name Seika Cure S, Wakayama Seika Co., Ltd. DICY: dicyandiamide, manufactured by Yuka Shell Chemical Company

[0066]

The epoxy resin composition of the present invention has excellent self-adhesiveness due to good fillet formation, high adhesive strength, and a cured product having excellent heat resistance. The composition of the present invention is useful as a matrix resin composition for prepreg impregnation to be bonded to a honeycomb. A prepreg using the composition of the present invention as a matrix resin eliminates the need for a conventionally used sheet adhesive. Therefore, not only is the step of installing the adhesive sheet unnecessary, but also it is possible to reduce auxiliary materials such as release paper used for the sheet, thereby giving full consideration to the preservation of the global environment. The structure of the prepreg and the honeycomb using the composition of the present invention as a matrix resin for impregnation can obtain a uniform adhesive force over the entire joint surface between the prepreg and the honeycomb, and is excellent in heat resistance.

[Brief description of the drawings]

FIG. 1 is a perspective view of a structure including a honeycomb and a prepreg.

FIG. 2 is a cross-sectional view of a structure including a honeycomb and a prepreg.

FIG. 3 is a graph schematically showing a relationship between a temperature and a complex viscosity in curing of an epoxy resin composition.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Structure 10 Prepreg 11 Honeycomb 12 End part 13 Upper surface part 13 'Lower surface part 14 Upper fillet 14' Lower fillet a Structure using prepreg formed of conventional matrix resin b Book using composition of the present invention as matrix resin Structure using the prepreg of the invention c Cell size

Continued on the front page (72) Inventor Mitsuhiro Iwata 2-1 Oiwake, Hiratsuka-shi, Kanagawa F-term in Yokohama Rubber Co., Ltd. Hiratsuka Works 4J036 AB01 AC02 AC03 AD07 AD08 AD09 AD11 AE07 AF06 AG05 AH06 AH07 AJ08 AK02 DA01 DC02 DC03 DC10 DC14 DC15 DD01 DD04 DD05 FB02 FB03 FB05 JA06 JA11 4J040 CA072 CA082 CA172 DA052 DA062 DA122 DA142 DF002 EC021 EC051 EC061 EC071 EC091 EC261 EC271 EC281 GA03 GA07 GA19 HC08 HD16 KA16 LA06 LA08 MB08 NA15

Claims (5)

[Claims] 1. An epoxy resin composition containing an epoxy resin, an aromatic amine-based curing agent, and a solid rubber compatible with the epoxy resin, wherein the complex is measured at a vibration frequency of 0.02 Hz at 50 to 150 ° C. Minimum value of viscosity η
_0.02 exists in the range of 1.0 to 200 Pa · s, and
During the curing of the resin composition, the complex viscosity is 1000 Pa ·
and the temperature T _low on the low temperature side that gives s
The temperature T _high on the high temperature side that gives s is 80 ° C. ≦ T _high −
An epoxy resin composition characterized by satisfying a relationship of T _low ≦ 150 ° C. 2. The epoxy resin includes an epoxy resin having an N-glycidylamino group, and further includes a bifunctional or higher epoxy resin, wherein at least one of the bifunctional or higher epoxy resin has a naphthalene ring, The epoxy resin composition according to claim 1, wherein the epoxy resin composition has at least one functional group selected from the group consisting of a pentadiene group, a bisphenyl group, and a fluorene group. 3. The epoxy resin composition according to claim 1, wherein the aromatic amine curing agent is an aromatic amine compound having one or more amino groups. 4. The acrylonitrile-butadiene rubber (N) which is compatible with the epoxy resin according to claim 2,
The epoxy resin composition according to claim 2, wherein the epoxy resin composition is BR). 5. An epoxy resin having at least one of the above-mentioned difunctional or higher functional epoxy resin, wherein (a) an epoxy resin having a dicyclopentadiene group, and (b) an epoxy resin having an N-glycidylamino group. Is an aromatic epoxy resin having an aromatic amine-based curing agent,
(C) diaminodiphenylsulfone, wherein in all epoxy resins, (a) an epoxy resin having a dicyclopentadiene group is 15% by weight or more, and
(B) The amount of the aromatic epoxy resin having a glycidylamino group is 50% by weight or more, and the total amount of (a) and (b) is 65 to 95% by weight.
The epoxy resin composition according to any one of items 1 to 4,