JP3137733B2 - Prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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-elasticity fibers such as carbon fibers as reinforcing materials have been widely used for sports applications, taking advantage of their excellent 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.

However, thermosetting resins typified by epoxy resins have various characteristics other than the above-mentioned characteristics, such as excellent heat resistance, solvent resistance, and mechanical characteristics, but are poor in toughness, and therefore have a high impact resistance. 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 and solvent resistance is suppressed as compared with the addition of a rubber component, but a large amount of addition is necessary 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]

DISCLOSURE OF THE INVENTION The present invention provides a molded article having excellent toughness without impairing the excellent handling, thermal and mechanical properties inherent in a prepreg having a thermosetting resin as a matrix. An object of the present invention is to provide a prepreg for a fiber-reinforced composite material that can be applied.

[0010]

According to the present invention, there are provided (A) a reinforcing fiber having an elastic modulus of 200 GPa or more;
Shear modulus in the temperature range of 0 ° C. is from 250 to 5000
A fibrous thermoplastic resin obtained by spinning a thermoplastic resin in the range of MPa, and (C) a prepreg for a fiber-reinforced composite material comprising a thermosetting matrix resin,
A prepreg characterized in that the fibrous thermoplastic resin (B) is localized on the outer surface.

In the present invention, (B) of -60 ° C. to 100 ° C.
Shear modulus in the temperature range of 250C to 250-5000M
The fibrous thermoplastic resin obtained by spinning a thermoplastic resin within the range of Pa is the most important component in the present invention. For the first time, using a fibrous shaped thermoplastic resin, without impairing the excellent handling, thermal and mechanical properties inherent in the base prepreg consisting of reinforcing fibers and a thermosetting matrix resin ,
This is because a prepreg for a fiber-reinforced composite material that can impart excellent toughness to a molded product can be obtained. In other words, since the thermoplastic resin can be effectively arranged on the surface layer of the prepreg by shaping into a fibrous form, sufficient improvement in toughness can be achieved with a small amount of the thermoplastic resin, and the tack level of the prepreg can be improved. Is easy to control, so that the problem of lowering the tack level, which is a problem in the prior art, does not occur, and furthermore, the distribution of the thermoplastic resin component is easier to control than in the conventional technology such as a fine particle addition system. For,
To that extent, there is an advantage that quality control is easy, and there is no problem in the process because the conventional prepreg manufacturing process can be used as it is.

The thermoplastic resin used has a shear modulus of 250 to 500 in a temperature range of -60 ° C to 100 ° C.
It is also important to be within the range of 0 MPa. In this temperature range, when a thermoplastic resin having a shear elastic modulus of 5000 MPa or less is used, the effect of improving the toughness as a composite material is particularly large. By using a thermoplastic resin of 250 MPa or more, interlaminar shear strength accompanying a decrease in rigidity as a matrix is given. This is because it is possible to avoid a decrease in The shear modulus in the present invention is a shear modulus measured under the following conditions.

[Method of Measuring Shear Modulus] Apparatus: RDS-7700 manufactured by Rheometrics
And equivalents Specimen shape: 12mm width x 2mm thickness x 40-50mm
Length mode: Temperature Sweep Start temperature: -90 ° C Temperature rise rate: 2 ° C / min Strain rate: 10 RAD / SEC Initial strain: 0.1% In the temperature range of -60 ° C to 100 ° C of (B) in the present invention. As a thermoplastic resin having a shear modulus in the range of 250 to 5000 MPa, almost any amorphous thermoplastic resin having a glass transition temperature (Tg) of 100 ° C. or more, and any crystalline thermoplastic resin can be used. Some high-modulus thermoplastic resins such as polyparaphenylenebenzbisthiazole are not preferred because of poor toughness improving effect. Conversely, the shear rigidity at 100 ° C. of polyethylene or the like is 250 MPa
A thermoplastic resin having a shear strength of less than 100
It is not preferable because it cannot be maintained at around ℃. Examples of particularly preferred thermoplastic resins include amorphous polyamide, polyetherimide, polyamideimide, thermoplastic polyimide, polyarylate, polysulfone, and the like.
A more preferable range of the shear modulus is 500 to 2500MP.
a.

Further, the fibrous thermoplastic resin (B) in the present invention is particularly preferably one having a functional group capable of reacting with the thermosetting matrix resin (C) in the molecule.

Therefore, when the thermosetting matrix resin (C) is an epoxy resin, the fibrous thermoplastic resin (B) can react with an epoxy resin such as an amino group, an amide group or a phenolic hydroxyl group. Those having a functional group are particularly preferred.

The form of the fibrous thermoplastic resin 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, the total denier is preferably 1,000 denier or less, particularly preferably 500 denier or less.

It is also possible to use a combination of two or more kinds of fibrous thermoplastic resins having different materials and deniers. The method of combination is not particularly limited, and a method of alternately aligning two kinds of fibers or a method of using as a mixed yarn by interlace processing may be appropriately employed. Further, a composite yarn having a core / sheath structure, a sea-island structure or the like obtained by composite spinning of two or more thermoplastic resins can also be used. The use of two or more fibers having different properties as a composite yarn or a mixed yarn is one of the effective methods for balancing various properties. A spun yarn obtained by spinning a short fiber can also be exemplified as one preferable embodiment of the fibrous thermoplastic resin (B).

The ratio of the fibrous thermoplastic resin (B) is 40 parts by weight or less, preferably 0.5 to 20 parts by weight, per 100 parts by weight of the thermosetting matrix resin (C). If the amount is less than 0.5 part by weight, a sufficient toughness-improving effect cannot be obtained, while if it exceeds 40 parts by weight, not only the toughness-improving effect reaches a plateau, but also the tack level of the prepreg undesirably decreases.

It is important that the fibrous thermoplastic resin (B) in the present invention exists near the outer surface of the prepreg. In the state of being completely buried in the center of the prepreg, a sufficient toughness improving effect cannot be obtained. However, it is still not preferable that the fibrous thermoplastic resin is completely raised from the surface of the prepreg, and most of the fibrous thermoplastic resin is preferably buried in the thermosetting matrix resin. Further, it is more preferable that the fibrous thermoplastic resin is aligned in one direction at equal intervals, but it is not necessarily limited thereto. Of course, it is also possible to arrange them in two or more directions at the same time, and to arrange them in a crossed manner, so that a high effect can be obtained, but the process becomes complicated. There is no particular limitation on the alignment direction, and the alignment direction may exist at any angle with respect to the reinforcing fibers, but it is easiest in the process to align in the same direction as the reinforcing fibers.

The elastic modulus (A) of the present invention is 200 GP.
As the reinforcing fibers of a or more, carbon fibers, graphite fibers, reinforcing fibers used in ordinary fiber-reinforced composite materials such as boron fibers are used as they are, but carbon fibers and graphite fibers having a tensile strength of 3500 MPa or more are preferably used. . Among them, high strength and high elongation carbon fiber and graphite fiber 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 (C) 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, resins having a nadic acid terminal. Is raised.

An epoxy resin is used as the thermosetting matrix resin most suitable for the present invention. 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 capable of reacting with the epoxy resin such as an amino group or an acid anhydride group is appropriately used. Although aromatic amines represented by various isomers of diaminodiphenylsulfone, dicyandiamide, and aminobenzoates are suitable.

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

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. When the addition amount of the thermoplastic resin component is 30% by weight or more, the viscosity of the system becomes too high, which causes not only impregnation failure at the time of prepreg formation, but also causes a significant decrease in tackiness and drape properties of the prepreg. Become.

In addition, inorganic fine particles such as fine powder silica and an elastomer component such as butadiene / acrylonitrile copolymer are added to the thermosetting resin 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 of the reinforcing fiber (A) having a modulus of elasticity of 200 GPa or more to the thermosetting matrix resin (C) can be appropriately set according to the purpose. (C) = The range of 40/60 to 85/15 is appropriate. A more preferred range is (A) / (C) = 60/40 to 75/25.

The method for producing a prepreg from the reinforcing fibers (A) having a modulus of 200 GPa or more, the thermosetting matrix resin (C) and the fibrous thermoplastic resin having a modulus of 100 GPa or less (B) is particularly limited. Therefore, any method can be used as long as the desired prepreg can be obtained. For example, the following methods can be exemplified, but are not necessarily limited thereto.

[Method 1] The fibrous thermoplastic resin of (B) is arranged on a base prepreg obtained from the reinforcing fibers of (A) and the thermosetting matrix resin of (C), and is impregnated with heat.

[Method 2] The reinforcing fiber of (A) and the reinforcing fiber of (B) are coated on release paper coated with the thermosetting matrix resin of (C).
And simultaneously impregnating the fibrous thermoplastic resin.

[Method 3] After the fibrous thermoplastic resin of (B) is arranged and fixed on the release paper coated with the thermosetting matrix resin of (C), the reinforcing fibers of (A) are overlapped and impregnated. .

[0034]

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

YH434L; tetraglycidyl diamine type epoxy resin (manufactured by Toto Kasei Co., Ltd.) ELM-100; triglycidyl diamine type epoxy resin (manufactured by Sumitomo Chemical Co., Ltd.) Epicoat 807; bisphenol F type epoxy resin (manufactured by Yuka Shell Co., Ltd.) 1 Epicoat 807,680 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 these pre-reacted products. To 35 parts by weight of this prereaction product, 25 parts by weight of Epicoat 807, 40 parts by weight of YH434L, and 50 parts by weight of diaminodiphenylsulfone as a curing agent were mixed 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. Prepreg C
The F weight was 190 g / m ² and the resin content was 34% by weight.

Amorphous nylon on both sides of the prepreg,
TR-55 (manufactured by EMS-CHEMIEAG; shear modulus at −60 ° C. = 1100 MPa, shear modulus at 100 ° C. =
720MPa) multifilament (150d, 18
fil) was wound at 2.5 mm intervals 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 270 lb-in impact was measured according to the mmend Method SRM2-88.
The obtained compressive strength after impact was 342 MPa.

Further, a width of 6.4 from a molded plate having the same lamination structure.
A test piece having a length of 30 mm and a length of 30 mm was cut out, and the interlaminar shear strength at 82 ° C. was measured under the conditions of L / D = 4 and crosshead speed = 1 mm / min. The resulting interlayer shear strength is 59
MPa.

Comparative Example 1 A unidirectional prepreg was produced in the same manner as in Example 1 except that a resin film having a resin content of 36% by weight was used. Using this prepreg, the compression strength after impact and the interlaminar shear strength were measured in the same manner as in Example 1 without adhering TR-55 fibers.

The obtained compressive strength after impact is 274MP.
a, Interlaminar shear strength at 82 ° C. was 62 MPa.

Example 2 Instead of TR-55, amorphous nylon, Trogam
id-T (manufactured by Dynamit Nobel; -60 ° C)
A prepreg was produced in the same manner as in Example 1 except that a multifilament (total denier 150d, number of filaments 18fil) having a shear modulus of 1500 MPa and a shear modulus at 100 ° C of 940 MPa was used. The shear strength was measured.

The obtained compressive strength after impact is 337 MPa.
a, Interlaminar shear strength at 82 ° C. was 61 MPa.

Comparative Example 2 A prepreg was produced in the same manner as in Example 1 except that a multifilament (total denier: 150 d, number of filaments: 18 fil) of nylon 12 (shear modulus at 100 ° C. = 140 MPa) was used instead of TR-55. Then, the compression strength and the interlaminar shear strength after impact were measured. The obtained compressive strength after impact was 346 MPa, and the interlaminar shear strength at 82 ° C. was 44 MPa.

Example 3 Instead of TR-55, polyetherimide ULTEM was used.
1000 (manufactured by General Electric);-
A prepreg was produced in the same manner as in Example 1 except that a multifilament (total denier 150d, number of filaments 18fil) having a shear modulus at 60 ° C of 1700 MPa and a shear modulus at 100 ° C = 1250 MPa was used, and the compressive strength after impact. The interlaminar shear strength was measured.

The obtained compressive strength after impact is 332 MP.
a, Interlaminar shear strength at 82 ° C. was 62 MPa.

Comparative Example 3 A prepreg was produced in the same manner as in Example 1 except that a multifilament (total denier: 150 d, number of filaments: 18 fil) of nylon 66 (shear modulus at 100 ° C. = 130 MPa) was used instead of TR-55. Then, the compression strength and the interlaminar shear strength after impact were measured. The obtained compressive strength after impact is 321 MPa, and the interlaminar shear strength is 42 MP.
a.

[0048]

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 B29K 105: 08 C08L 63:00 (72) Inventor Takashi Murata 4-160 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Japan Mitsubishi Rayon Co., Ltd. Development Research Institute (72) Inventor Tsutomu Ibuki 4-160 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Tetsuya Yamaoka 4-1-1 Ushikawa-dori, Toyohashi City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Toyohashi Works (72) Inventor Takashi Akita 4-2-1 Ushikawadori, Toyohashi City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Toyohashi Works Examiner Hiroki Amano (56) References JP-A-60-63229 (JP, A) JP-A-60-231738 (JP, A) JP-A-2-32843 (JP, A) JP-A-3-143917 (JP, A) Flat 5-9310 (JP, A) JP flat 5-202288 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) B29B 11/16 B29B 15/08 C08J 5/24

Claims (10)

(57) [Claims] 1. A fiber obtained by spinning (A) a reinforcing fiber having an elastic modulus of 200 GPa or more, and (B) a thermoplastic resin having a shear elastic modulus within a range of 250 to 5000 MPa in a temperature range of -60 ° C to 100 ° C. (C) a prepreg for a fiber-reinforced composite material comprising a thermosetting matrix resin, wherein the fibrous thermoplastic resin (B) is localized on the outer surface thereof. Prepreg to be characterized . 2. The ratio of each of the components (A), (B) and (C) is
2. The prepreg according to claim 1, which is in the following range:.  (A) / (C) = 40 / 60-85 / 15 (weight ratio) (B) / (C) = 0.5 / 100-40 / 100 (weight
Quantity ratio) 3. The ratio of each of the components (A), (B) and (C) is
2. The prepreg according to claim 1, which is in the following range:.  (A) / (C) = 60 / 40-75 / 25 (weight ratio) (B) / (C) = 0.5 / 100-20 / 100 (weight
Quantity ratio) 4. The prepreg according to claim 1, wherein (A) is a carbon fiber or a graphite fiber having a tensile strength of 3500 MPa or more . 5. The prepreg according to claim 1, wherein the fibrous thermoplastic resin (B) is a monofilament or a multifilament . 6. The prepreg according to claim 1, wherein the fibrous thermoplastic resin (B) is locally arranged on the outer surface thereof at a certain interval in one direction . 7. The prepreg according to claim 1, wherein (C) is a thermosetting matrix resin containing an epoxy resin as a main component . 8. The fibrous thermoplastic resin of (B) is an epoxy resin.
The prepreg according to claim 7, which is a fibrous material of a thermoplastic resin having a functional group capable of reacting with the resin . 9. The method according to claim 9, wherein the functional group capable of reacting with the epoxy resin is
9. A thio group, an amide group or a phenolic hydroxyl group.
The prepreg described. 10. The prepreg according to claim 7, wherein the fibrous thermoplastic resin (B) is a fibrous amorphous polyamide .