JP3145182B2 - Prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention can impart excellent toughness to a molded product without impairing excellent handling, thermal and mechanical properties inherent in a prepreg having a thermosetting resin as a matrix. The present invention relates to a prepreg for a fiber-reinforced composite material.

[0002]

2. Description of the Related Art Advanced composite materials using high-strength and high-elastic fibers such as carbon fibers as reinforcing materials have been widely used mainly for sports applications, taking advantage of their characteristics of being excellent in specific strength and specific elasticity.

[0003] Since these advanced composite materials are generally provided and used in the form of an intermediate base material called a prepreg, the matrix resin has an appropriate tackiness (tack) and flexibility (tack) required for laminating the prepreg. A thermosetting resin that can easily impart drape property is usually used as a matrix resin.

[0004] However, thermosetting resins typified by epoxy resins have various features such as excellent heat resistance, solvent resistance, and mechanical properties in addition to the above-mentioned features, but have poor toughness due to poor toughness. It has a drawback that it is inferior in properties. Especially when the advanced composite material is used as a laminate, the resistance to impact is often governed by the delamination strength, so the impact resistance of the advanced composite material using a low-toughness thermosetting resin as the matrix is also low. As a result, the applications of advanced composite materials, especially as structural materials, have been considerably limited.

As a method of improving the disadvantages of the thermosetting matrix resin, for example, a method of adding a rubber component is known, but it is necessary to add a large amount in order to obtain a sufficient toughness improving effect. As a result, the heat resistance, the solvent resistance and the like were significantly reduced.

A method of adding a thermoplastic resin, especially a so-called engineering plastic having excellent heat resistance and solvent resistance, has also been proposed (Japanese Patent Application Laid-Open No. 61-21254).
3, JP-A-61-228016, JP-A-58-1341
11), it is reported that the decrease in heat resistance, solvent resistance, etc. is suppressed as compared with the addition of rubber components, but a large amount of addition is required to obtain sufficient toughness, and the viscosity of the entire system increases. However, this method still has a serious problem that the process passability during the production of the prepreg decreases or the tack level of the prepreg decreases.

Attempts to improve the toughness of the thermosetting matrix resin itself are not very effective from the viewpoint of improving the delamination strength of the laminate. For the purpose of effectively improving the delamination strength of the laminate, a method of intensively dispersing fine particles of a thermoplastic resin between layers has also been proposed (Japanese Patent Laid-Open No. 1-110537), but the tack level of the prepreg does not significantly decrease. In addition to the inevitable problems, new problems such as complicated processes and complicated quality control arise. Attempts to localize chopped fibers, milled fibers, and the like between layers for the same purpose have been proposed, but not only are similar problems unavoidable, but their effects are not always satisfactory.

Further, a method of inserting a kind of a shock absorbing layer called an interleaf between layers has been proposed (for example, US Pat. No. 3,472,730, Japanese Patent Laid-Open No. 51-584).
84, JP-A-60-63229, JP-A-60-2317
38 etc.), the thickness of the layers is increased, the fiber ratio is reduced, and the heat resistance and handleability are reduced, so that they have not been widely used.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a prepreg having a thermosetting resin as a matrix without impairing the excellent handling, thermal and mechanical properties inherently possessed by the prepreg.
An object of the present invention is to provide a prepreg for a fiber-reinforced composite material that can impart excellent toughness to the obtained molded product.

[0010]

According to the present invention, an elastic modulus of 200 is provided.
A glass transition temperature (Tg) is applied to the surface of a prepreg composed of a reinforcing fiber of GPa or more and a thermosetting matrix resin.
Has a core component of a thermoplastic resin having a temperature of 100 ° C. or higher and a Tg of 1
A basis weight of ^{2 to 20} g / m ² obtained by weaving using a core / sheath structure fiber having a polyamide resin having a sheath component of less than 00 ° C.
The gist of the present invention is a prepreg characterized by laminating woven fabrics.

In the present invention, the basis weight obtained by weaving using a core / sheath fiber comprising a thermoplastic resin having a Tg of 100 ° C. or higher as a core component and a polyamide resin having a Tg of less than 100 ° C. as a sheath component 2 Laminating a woven fabric of ２０20 g / m ² is the most important component.

This is because Tg is 1 as a toughness-imparting component.
Use of a polyamide having a temperature of less than 00 ° C. is particularly desirable when an epoxy resin is used as a matrix, but is not practically usable because the heat resistance of the composite material is lowered due to a low Tg. On the other hand, a thermoplastic resin having a Tg of 100 ° C. or higher does not have a problem of a decrease in heat resistance, but does not have a sufficient toughness improving effect.

The present inventors have conducted intensive studies to achieve both conflicting propositions of improving toughness and maintaining heat resistance. As a result, a thermoplastic resin having a Tg of 100 ° C. or more was used as a core component.
The inventors have found that these propositions can be achieved by using a fiber having a core / sheath structure in which a polyamide resin having a Tg of less than 100 ° C. is a sheath component, and reached the present invention.

The polyamide resin used as the sheath component of the core / sheath structure fiber in the present invention includes nylon 6, nylon 66, nylon 612, nylon 12, nylon 11
For example, ordinary crystalline nylon can be used, but those having low hygroscopicity are more preferable.

The core component is not particularly limited as long as it is a thermoplastic resin having a Tg of 100 ° C. or higher, and any resin can be used. However, amorphous polyamide is particularly preferable from the viewpoint of compatibility with the sheath component. preferable. Representative examples of amorphous polyamides include TR-55 (Tg = 155 ° C.) of Ems and Trogamid-T (Tg = Tg) of Daicel Huels.
148 ° C).

It is also very important to use a coarse woven fabric having a basis weight of ^{2 to 20} g / m ² as a woven fabric composed of fibers having a core / sheath structure. That is, by using a coarse woven fabric, it is possible to effectively arrange the toughness-imparting component in the surface layer of the prepreg, so that a small amount of the toughness-imparting component can achieve sufficient toughness improvement, Because of the coarseness, the original tack level of the base prepreg composed of the reinforcing fibers and the thermosetting resin is maintained as it is, so that the problem of a decrease in tack level, which is a problem in the prior art, does not occur. Furthermore, compared to the prior art such as a fine particle addition system,
There is no problem of controlling the distribution of the toughness-imparting component, and the quality control is easy. In addition, the conventional process can be used as it is for the production of prepreg, so that there is no problem in the process.

The form of the core / sheath fiber is preferably a monofilament or a multifilament obtained by bundling them, but is not necessarily limited thereto. The diameter of each filament is preferably 100 μm or less, particularly preferably 50 μm or less. When used as a multifilament, total denier is 100
It is preferably 0 denier or less, particularly preferably 500 denier or less. The method of weaving using these fibers having a core / sheath structure is not particularly limited, and any method can be used as long as it can weave a coarse woven fabric having a basis weight of ^{2 to 20} g / m ^2. It is.

The ratio of the fibers having a core / sheath structure to the thermosetting matrix resin is 25 parts by weight or less, preferably 5 to 10 parts by weight, per 100 parts by weight of the thermosetting matrix resin.

As the reinforcing fibers having an elastic modulus of 200 GPa or more in the present invention, reinforcing fibers used in ordinary fiber-reinforced composite materials, such as carbon fibers, graphite fibers, and boron fibers, can be used as they are, but they have a tensile strength of 3500 MPa or more. Carbon fibers or graphite fibers are preferably used. Above all,
High strength and high elongation carbon fibers or graphite fibers having a tensile strength of 4500 MPa or more and an elongation of 1.7% or more are most preferably used.

As the thermosetting matrix resin in the present invention, any resin can be used as long as it is cured and at least partially forms a three-dimensional cured product.

Typical examples are epoxy resins, maleimide resins, polyimide resins, resins having a cyanate ester terminal, resins having an acetylene terminal, resins having a vinyl terminal, resins having an allyl terminal, and resins having a nadic acid terminal. Is raised.

As the thermosetting matrix resin most suitable for the present invention, an epoxy resin is used. Particularly, an epoxy resin using an amine or a phenol as a precursor is preferable. Specifically, tetraglycidyldiaminodiphenylmethane, triglycidyl-p-aminophenol, triglycidyl-m-aminophenol, various isomers of triglycidylaminocresol, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type Examples include, but are not limited to, epoxy resins, phenol novolak epoxy resins, cresol novolak epoxy resins, and the like. A brominated epoxy resin obtained by brominating these epoxy resins is also used. These epoxy resins may be used alone, but may be used as a mixture of two or more types depending on the purpose.

The epoxy resin is usually used in combination with a curing agent, but the curing agent used in the present invention is not particularly limited, and a functional group that can react with the epoxy resin, such as an amino group or an acid anhydride group, may be appropriately used. However, aromatic amines represented by various isomers of diaminodiphenylsulfone, dicyandiamide, and aminobenzoic acid esters are suitable.

Particularly preferred as the epoxy resin is an epoxy resin composition comprising the following (a), (b) and (c).

(A) 20 parts to the total amount of the matrix resin
(B) 10 to 50% by weight, based on the total amount of the matrix resin, of a pre-reaction product of the epoxy resin and the bifunctional phenol compound, substantially free of phenolic hydroxyl groups; (C) 0.8 to 1.7 equivalents of an aromatic diamine curing agent based on the epoxy groups of (a) and (b).

The epoxy resin composition comprising the above (a), (b), and (c) has a high toughness, and when used as a matrix resin, it can be extremely combined with an amorphous polyamide fabric having a small basis weight. A fiber-reinforced composite material molded article exhibiting high impact resistance is obtained.

As the thermosetting matrix resin in the present invention, a resin obtained by adding a thermoplastic resin or an oligomer thereof to the above-mentioned thermosetting resin can also be used. In particular, so-called engineering plastics such as polyimide, polyetherimide, polysulfone, polyethersulfone, and polyetheretherketone are preferable from the viewpoint of heat resistance, and have a functional group capable of reacting with a thermosetting resin at a molecular terminal or in a molecular chain. Is more preferred.

The addition amount of the thermoplastic resin component to the thermosetting resin component is preferably 30% by weight or less, more preferably 15% by weight or less. If the addition amount of the thermoplastic resin component exceeds 30% by weight, not only does the viscosity of the system become too high, which causes impregnation failure during prepreg formation, but also causes the tack property and drape property of the prepreg to significantly decrease. Become.

Further, a thermosetting resin may be mixed with inorganic fine particles such as fine powder silica or an elastomer component such as butadiene / acrylonitrile copolymer in a small amount within a range not sacrificing prepreg characteristics, processing characteristics, mechanical characteristics, thermal characteristics, and the like. It is also possible to add.

The ratio between the reinforcing fiber (A) having an elastic modulus of 200 GPa or more and the thermosetting matrix resin (C) can be appropriately set according to the purpose, but the weight ratio is (A) / (C). ) = 40/60 to 85/15. A more preferred range is as follows.

(A) / (C) = 60 / 40-75 / 25

[0032]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

In the examples, the blending parts are all parts by weight, and the epoxy resins used are as follows.

YH434L; tetraglycidyl diamine type epoxy resin (manufactured by Toto Kasei Co., Ltd.) ELM-100; triglycidylamine type epoxy resin (manufactured by Sumitomo Chemical Co., Ltd.) Epicoat 807; bisphenol F type epoxy resin (manufactured by Yuka Shell Co., Ltd.) Example 1] Amorphous nylon, TR-55 (EMS-CHEMIE
AG: Tg = 155 ° C.)
After vacuum drying for a period of time, the mixture is melted using the first extruder, while nylon 12 (Daicel Huls: L
2140: Tg = 41 ° C.), vacuum-dried at 80 ° C. for 12 hours, and then melted using a second extruder. Each melt stream was led to a spinning head, and TR-55 was a core component. And the ratio of the core component / sheath component is 70 / by volume ratio.
After forming a composite stream to reach a spinning temperature of 30
Melt spinning was performed at 5 ° C. and a spinning speed of 700 m / min to obtain a core / sheath structural fiber having a total denier of 90 d and 18 filaments.

Example 1 Epicoats 807 and 680
g, ELM-100, 477 g, and tetramethylbisphenol A, 426 g were charged into a reaction vessel and reacted at 120 ° C. for 8 hours to obtain a pre-reacted product. 35 parts by weight of the pre-reacted product, 807, 25 parts by weight of epicoat and YH
434 L, 40 parts by weight, and 50 parts by weight of diaminodiphenylsulfone as a curing agent were blended and thoroughly mixed until the whole became uniform.

The obtained resin composition and Mitsubishi Rayon Co., Ltd.
Prepreg was manufactured from the high-strength medium-elasticity carbon fiber and MR60P by a hot melt method. The CF basis weight of this prepreg was 190 g / m ² , and the resin content was 34% by weight.

A basis weight of 5 g obtained by weaving both sides of the prepreg with the core / sheath structure fiber produced in Reference Example 1 was obtained.
/ M ² of fabric was bonded to both sides of the prepreg to produce a prepreg of the present invention. A small piece of a predetermined size was cut out from this prepreg, and after lamination, a test piece for measuring compressive strength after impact was formed by autoclave molding. (Curing conditions: 180 ° C. × 2 hours) Using this test piece, SACMA (Suppliers
of Advanced Composite Ma
Reco of terials Association)
The compressive strength after a 2701 b-in impact was measured according to the mmend Method SRM2-88.
The obtained compressive strength after impact was 357 MPa.

Further, a width of 6.4 from a molded plate having the same lamination structure.
mm, a test piece having a length of 30 mm was cut out, and L / D = 4.
82 ° C. under the condition of crosshead speed = 1 mm / min
Was measured for the interlaminar shear strength. The obtained interlayer shear strength was 56 MPa.

[Comparative Example 1] The resin content of the prepreg was 3
A one-way prepreg was produced in the same manner as in Example 1 except that a resin film having a concentration of 6% by weight was used. Using this prepreg, the compressive strength after impact and the interlaminar shear strength at 82 ° C. were measured in the same manner as in Example 1 without adhering the woven fabric of the core / sheath structure fiber. The obtained compressive strength after impact is 274 MPa, and the interlaminar shear strength at 82 ° C. is 62 M.
Pa.

Reference Example 2 Amorphous nylon was TR-55
To Trogamid-T (Daicel Hulls: T
g = 148 ° C.) and the core component (Trogamid-
T) / sheath component (nylon 12) in a volume ratio of 50 /
A total denier of 90 d and a core / sheath structure fiber of 18 filaments were obtained in the same manner as in Reference Example 1 except that the discharge amount was adjusted to 50.

Example 2 The procedure of Example 1 was repeated except that the core / sheath structure fiber produced in Reference Example 2 was used instead of the core / sheath structure fiber produced in Reference Example 1 (weight per unit area: 5 g / m ² ). A prepreg was produced in the same manner as described above, and the compression strength after impact and the interlaminar shear strength at 82 ° C. were measured. The obtained compressive strength after impact is 348 MPa, and the interlaminar shear strength at 82 ° C. is 5
It was 7 MPa.

[0042]

The prepreg of the present invention has not only the same excellent handling properties as the prepreg using a conventional thermosetting resin as a matrix, but also a molded product obtained without impairing the thermal and mechanical properties. It can provide excellent toughness, and particularly has high resistance to delamination when subjected to an impact, so that it is suitably used as a structural material for aircraft or the like.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI B32B 17/04 B32B 17/04 Z 27/38 27/38 // C08L 63:00 (72) Inventor Tadashi Yokochi Tada Sunadahashi, Higashi-ku, Nagoya City, Aichi Prefecture No. 1-60, Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Takeshi Goto 4-6-1 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Laboratory (72) Inventor Tetsuya Yamaoka Toyohashi, Aichi Prefecture Hiroshi Amano, Mitsubishi Rayon Co., Ltd. 4-1-1, Ushikawa-dori, Toyohashi-shi, Aichi, Japan (72) Inventor Takashi Akita Takashi Akano Document JP-A-2-32843 (JP, A) JP-A-5-329838 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 5/24 B29B 11/16 B32B 5 / 00-5/32 B32B 17/04 B32B 27/38

Claims (4)

(57) [Claims] 1. A prepreg comprising a reinforcing fiber having an elastic modulus of 200 GPa or more and a thermosetting matrix resin, a thermoplastic resin having a glass transition temperature (Tg) of 100 ° C. or more as a core component, and a Tg of 100 ° C. A prepreg, wherein a woven fabric having a basis weight of ^{2 to 20} g / m ² obtained by weaving using fibers having a core / sheath structure having less than a polyamide resin as a sheath component is bonded. 2. The prepreg according to claim 1, wherein the reinforcing fibers are carbon fibers or graphite fibers having a tensile strength of 3500 MPa or more. 3. The prepreg according to claim 1, wherein the thermosetting matrix resin is a thermosetting resin comprising the following (a), (b) and (c). (A) 20 to 60% by weight based on the total amount of the matrix resin
Epoxy resin component. (B) 10 to 50% by weight based on the total amount of the matrix resin
A pre-reaction product of an epoxy resin and a bifunctional phenol compound substantially free of phenolic hydroxyl groups. (C) 0.8 with respect to the epoxy groups of (a) and (b).
~ 1.7 equivalents of aromatic diamine curing agent. 4. The prepreg according to claim 1, wherein the core component of the fiber having a core / sheath structure is an amorphous polyamide.