JP3065683B2 - Prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg for a fiber-reinforced composite material capable of imparting excellent toughness to a molded product obtained without impairing excellent thermal and mechanical properties of a matrix resin.

[0002]

2. Description of the Related Art Composite materials using high-strength and high-elasticity fibers such as carbon fibers as reinforcing materials are known in the art.
It has been widely used in sports applications, taking advantage of its characteristics of excellent specific strength and specific elasticity.

[0003] Thermosetting resins, such as epoxy resins, (bis) maleimide resins, and cyanate ester resins, which are usually used as matrix resins, have various characteristics, but have the drawback of poor toughness, so that their applications are poor. Was quite limited.

[0004] As a method of improving the disadvantages of the thermosetting resin, a method of adding a rubber component or a thermoplastic resin is generally used, but in order to obtain a sufficient toughness improving effect, it is necessary to add a large amount. As a result, heat resistance, solvent resistance and the like are reduced.

A method of inserting an adhesive layer called an interleaf between layers has also been proposed, but has not been put into practical use because the fiber content cannot be increased.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a prepreg for a fiber-reinforced composite material capable of imparting excellent toughness to a molded product obtained without impairing excellent thermal and mechanical properties of a matrix resin. is there.

[0007]

The gist of the present invention is that (A)
Reinforcing fiber with elastic modulus of 200 GPa or more (B) Fibrous thermoplastic resin with elastic modulus of 100 GPa or less (C) Mixture of polyfunctional maleimide (I) and polyfunctional cyanate ester or oligomer (II) thereof or (I) In the prepreg for a fiber-reinforced composite material composed of a matrix resin mainly composed of
A prepreg characterized in that the ratio of each of the components (A), (B) and (C) is within the following range, and the fibrous thermoplastic resin of (B) is present on its outer surface. . (A) / (C) = 60 / 40-75 / 25 (weight ratio) (B) / (C) = 0.5 / 100-40 / 100 (weight ratio)

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.

The mixture of the polyfunctional (bis) maleimide (I) of (C) and the polyfunctional cyanate ester or its oligomer (II) or the pre-reacted product of (I) and (II) is used in the present invention. The matrix resin as a main component is a mixture of (I) and (II) or (I) and (I).
A resin composition wherein the pre-reacted product of I) contains 30% by weight, preferably 40% by weight or more.

The polyfunctional maleimide (I) is a compound having two or more maleimide groups,

Embedded image (Wherein X represents a divalent aromatic or aliphatic group), as well as prepolymers obtained from these bismaleimides and diamines. The bismaleimide of the formula (1) can be produced by a known method in which bismaleamic acid is prepared by reacting maleic anhydride with a diamine, followed by dehydration cyclization.

As the diamine, an aromatic diamine is preferable from the viewpoint of heat resistance. However, when it is desired to provide a function such as flexibility, an aliphatic amine can be used alone or in combination. Examples of the diamine include m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane,
4'-diaminodiphenyl ether and the like are used.

The polyfunctional cyanate ester or its oligomer (II) used in the present invention is an organic compound having two or more cyanate ester groups and its oligomer, and has the general formula

Embedded image (Wherein n is an integer of 2 to 5, and Y represents an aromatic organic residue).

As the polyfunctional cyanate ester, 1,3
-Or 1,4-dicyanatobenzene, 4,4-dicyanatobiphenyl, bis (4-cyanatophenyl)
Methane, 2,2-bis (4-cyanatophenyl) ethane, 2,2-bis (4-cyanatophenyl) propane, bis (4-cyanatophenyl) sulfone and the like are used.

The above-mentioned polyfunctional cyanate ester can be used in the form of a prepolymer formed by a reaction with an amine, in addition to a triazine oligomer obtained by trimerization of a cyanate. Examples include those used in the synthesis and modification of maleimides.

The pre-reacted product obtained by pre-reacting the above-mentioned polyfunctional maleimide (I) and polyfunctional cyanate ester or its oligomer (II) alone or in the absence of a catalyst or in the presence of a catalyst may be suitably used depending on the application. Selected and used.

The ratio of (I) and (II) is expressed by weight ratio of (I) /
(II) = 5 to 15/95 to 85 is preferred. When the amount of (I) is more than 15, the hot water resistance is improved, but a high curing temperature is required, and the impact resistance tends to decrease. When the amount is less than 5, the impact resistance improves but the hot water resistance decreases. It is not preferable because it shows a tendency.

It is preferable to mix an epoxy resin to improve the adhesion to the substrate or to add a polyester compound for the purpose of improving the toughness.

The epoxy resin used may be a known epoxy resin, for example, the following compounds.
Polyglycidyl ethers of diphenylol alkanes such as diphenylolpropane, diphenylolethane and diphenylolmethane, polyglycidyl ethers of polyhydric phenols such as novolak, cresol and resol, cyclohexane, cyclopentadiene and dicyclopentadiene Epoxy resins formed by epoxidation of alicyclic compounds such as (3,4-epoxy-6) of 3,4-epoxy-6-methyl-cyclohexane-carboxylic acid
Poly (epoxyalkyl) ethers of aliphatic polyoxy compounds such as methyl-cyclohexane) -methyl ester, ethylene glycol and glycerin, and epoxyalkyl esters of carboxylic acids such as glycidyl esters of aromatic or aliphatic carboxylic acids. In addition, for example, U.S. Pat.
It may be a pre-reacted product of an epoxy resin and a curing agent as described in each specification of JP-A-67170, or may be a simple mixture.

These may be used alone or in combination of two or more. Suitable epoxy compounds include, for example, the diglycidyl ether of bisphenol A or the diglycidyl ether of bisphenol F, or the prereacted product of these epoxy compounds and diaminodiphenyl sulfone at an epoxy group / NH group ratio of 4/1.

The polyester compound has the general formula

Embedded image Or

Embedded image (Wherein Ar is a phenylene group, R ₁ is a divalent aliphatic group, R
₂ represents a divalent aromatic group or an aliphatic group), particularly preferably a compound in which the acid component is mainly terephthalic acid and the glycol component is mainly neopentyl glycol or ethylene glycol. It is important that the softening point of the polyester compound is 100 ° C. or lower, and it is better that the softening point is 70 ° C. or lower.

If the softening point exceeds 100 ° C., the compatibility with polyfunctional maleimides, polyfunctional cyanate esters and epoxy compounds becomes poor, and it becomes difficult to obtain a uniform composition. This polyester compound preferably has a number average molecular weight of 500 to 10,000, particularly preferably 500 to 3,000. If it is less than 500, the viscosity will be low, and if it exceeds 10,000, the workability of mixing with other components will be lacking, which is not suitable. The polyester compound used in the present invention can be produced by a general method used in producing another linear polyester.

The mixing ratio is multifunctional bismaleimide (I)
And a mixture of a polyfunctional cyanate ester or its oligomer (II) or a pre-reaction product 1 of (I) and (II)
It is preferable to use 5 to 100 parts by weight of the epoxy resin and 5 to 50 parts by weight of the polyester compound based on 00 parts by weight.

When the amount of the epoxy compound is less than 5 parts by weight, the adhesion to the substrate is poor, and when it exceeds 100 parts by weight, satisfactory heat resistance cannot be obtained. If the amount of the polyester compound is less than 5 parts by weight, sufficient impact resistance is not exhibited, and if it exceeds 50 parts by weight, heat resistance and solvent resistance are significantly reduced.

A catalyst may be added for the purpose of imparting desired properties to the cured resin or controlling the thermosetting property of the resin. Examples of the catalyst include a staying curing catalyst such as a boron trifluoride amine complex compound, triethylene diamine,
1,8-diazabicyclo (5.4.0) undecene,
Tertiary amines such as N, N-dimethylbenzylamine, N-methylmorpholine, tri-n-butylamine, organic peroxides such as dicumyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, zinc octylate ,
Organic acid metal salts such as tin octylate, zinc naphthenate, and cobalt naphthenate are exemplified. The amount of the catalyst used may be determined according to the purpose, but from the viewpoint of the stability of the resin composition, the amount is preferably 0.2 to 3% by weight based on the total resin solid components.

Further, reactive elastomers such as a carboxyl group-terminated butadiene / acrylonitrile copolymer, a carboxyl group-terminated polybutadiene, and an acryloyloxy group-terminated butadiene / acrylonitrile copolymer, and thermosetting resins such as an epoxy resin unsaturated polyester resin, a phenol resin, and a silicone resin. A curable resin, a thermoplastic resin such as polyether sulfone, polyetherimide, polyetheretherketone, thermoplastic imide, polyester, polyamide, or polyamideimide may be added. It is preferable that the addition amount of the thermoplastic resin be 30% by weight or less. 30
When used in excess of the weight percentage, the viscosity of the system becomes too high, which causes not only impregnation failure during prepreg formation but also causes a reduction in tackiness and drape properties of the prepreg.

It is also possible to mix a small amount of inorganic fine particles such as fine powder silica. The ratio of the reinforcing fiber of (A) to the matrix resin of (C) can be appropriately set according to the purpose, but the weight ratio of (A) / (C) = 60/40 to 75/25 A range is particularly preferred.

The elastic modulus (B) of the present invention is 100 GP.
The following fibrous thermoplastic resins include fibrous polyamides and polyesters as well as so-called engineering plastics and super engineering plastics such as polyetherimide, polyimide, polyamideimide, polybenzimidazole, polyarylsulfone, and polyetheretherketone. Is preferably used.

It is preferable to have a functional group capable of reacting with a matrix resin such as an amino group, a phenolic hydroxyl group, or an amide group in the molecular chain, and an engineering plastic having a functional group introduced into the terminal or into the molecular chain by means such as copolymerization. , Super-engineered plastic or polymer alloy is preferred.

The form of the fibrous thermoplastic resin is preferably a monofilament or a bundle thereof, but is not necessarily limited thereto. The diameter of the fiber is preferably 100 μm or less, more preferably 50 μm or less. Improving the toughness of the composite material can also be achieved by adding the thermoplastic resin to the resin in powder form.However, when the thermoplastic resin powder is uniformly dispersed or dissolved in the resin, Problems such as a decrease in processability during prepreg production or a decrease in tack level of the prepreg due to an increase in viscosity are inevitable.

Further, for example, Japanese Patent Application Laid-Open No. 1-110537 discloses that the toughness of the composite material is effectively improved by localizing spherical fine particles from the surface of the prepreg to a depth within 30% of the thickness of the prepreg. However, even in this case, a significant decrease in the tack of the prepreg is unavoidable, and further problems such as complicated processes and complicated quality control occur.

On the other hand, the method of using the fibrous thermoplastic resin of the present invention is as follows: 1) a small amount of thermoplastic resin can be arranged on the surface; 2) the tack level of the prepreg is easily controlled; There is no need to handle viscous materials and the conventional prepreg manufacturing process can be used as it is. 4) It has various features such as easy quality control. These are effects that cannot be obtained by the conventional technology, and are effects obtained only by using the fibrous thermoplastic resin in the present invention.

The ratio of the fibrous thermoplastic resin is preferably 0.5 to 40 parts by weight based on 100 parts by weight of the matrix resin (C). If the amount is less than 0.5 part by weight, a sufficient toughness improving effect cannot be obtained. Conversely, if the amount exceeds 40 parts by weight, the effect of improving the toughness will not only reach a peak even if a thermoplastic resin is used, but also the properties such as heat resistance and solvent resistance will be greatly reduced depending on the type of the resin used. Absent.

It is important that the fibrous thermoplastic resin 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 not preferable that the fibrous thermoplastic resin is completely raised from the prepreg surface, and it is preferable that most of the fibrous thermoplastic resin is buried in the resin. Further, it is more preferable that the fibrous thermoplastic resin is present in a state of being aligned in one direction at equal intervals.

The alignment direction is not particularly limited and may be present at any angle with respect to the reinforcing fiber, but it is easiest in the process to align in the same direction as the reinforcing fiber. There is no particular limitation on the method for producing such a prepreg from the reinforcing fiber and the matrix resin and the fibrous thermoplastic resin, and the resin film impregnated with the fibrous thermoplastic resin in advance and impregnated with the reinforcing fiber is usually used. The prepreg can be produced by a method similar to the method for producing a prepreg, a method in which a fibrous thermoplastic resin is aligned with a prepreg produced by a usual method, and integrated.

[0035]

The molded product obtained from the prepreg of the present invention is provided with excellent toughness without impairing the excellent thermal and mechanical properties of the matrix resin, and furthermore, the cracks generated can be propagated. Since it has difficult properties, it is suitably used as an aircraft structural material.

[0036]

The present invention will be described in detail with reference to the following examples. Examples 1-3 Bis (4-maleimidophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, epoxy equivalent 1
No. 72 Epicoat 807 (manufactured by Yuka Shell Co., Ltd.) and polyester having a softening point of 25 ° C. consisting of terephthalic acid as an acid component and neopentyl glycol as a glycol component are mixed at the ratio shown in Table 1, and further, aerosol 380 (micro silicon oxide powder) 1.25 parts of Nippon Aerosil Co., Ltd. and 0.2 part of dicumyl peroxide as a curing catalyst were added, and 70 ° C.
And high-strength medium elastic carbon fiber (Mitsubishi Rayon, MR-50K, tensile strength 5600M)
(Pa, elastic modulus 300 GPa) to produce a unidirectional prepreg by a hot melt method.

The prepreg has a basis weight of 145 g / m ² ,
The resin content was 34% by weight. Nylon 12 fibers (9) having an apparent thickness of about 40 μm were added to this prepreg.
0d / 36f) (elastic modulus of about 2 GPa) by 3.3 mm in the same direction as CF on both sides of the prepreg by the filament winding method so that the fiber basis weight per side is 3 g / m ^2.
The prepreg of the present invention was manufactured by winding at equal intervals and burying most of the nylon 12 fibers lightly in the prepreg.
A small piece of a predetermined size is cut out from this prepreg (+4
(5 ° / 0 ° / −45 ° / 90 °) After lamination to 4S, a test piece for measuring compressive strength after impact was prepared by autoclave molding.

The curing conditions were 180 ° C. × 2 hours and 5 atm. Using this test piece, SACMA (Supplier
s of Advanced Composite M
materials Association) Reco
The compressive strength after impact of 270 lb-in was measured according to the mmend Method SRM2-88, and the results shown in Table 1 were obtained.

Comparative Examples 1 to 3 Unidirectional prepregs were produced in the same manner as in Examples 1 to 3, except that a resin film in which the resin content of the prepreg was 36% by weight was used. Using this prepreg, evaluation was made in the same manner as in Example 1 without attaching nylon 12 fibers. The results are shown in Table 1.

[0040]

[Table 1]

Example 4 A prepreg having a resin content of 31% by weight and nylon 1
Polyetherimide fiber ( 300 d /
Prepreg was manufactured in the same manner as in Example 1 except that the wind spacing was 4.1 mm, and the compressive strength after impact was set to 24 g, using a modulus of elasticity of about 4 GPa) and a fiber weight per side of 8 g / m ^2. It was measured. The resulting compression strength after impact is 2
It was 78 MPa.

[0042] Using those polyether sulfone (VICTREX5003) instead of Example 5 polyetherimide fibers were melt shaping into a fibrous (250d / 36f, elastic modulus about 3 GPa),
The compressive strength after impact was measured in the same manner as in Example 4, except that the fiber spacing per one side was 8 g / m ² , except that the wind interval was 3.5 mm. The obtained compression strength after impact was 240 MPa.

Example 6 Polyarylsulfone (RADEL A-200, manufactured by Amoco) was melt-shaped into a fiber instead of polyetherimide fiber (300 d / 50 f, elastic modulus about 3 GP).
The compressive strength after impact was measured in the same manner as in Example 4 except for using a). The resulting compression strength after impact is 265M
Pa.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Murata Inventor, 4-1-1 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture Inside the Mitsubishi Rayon Co., Ltd. (72) Takeshi Kato 4-1-1 Sunadabashi, Higashi-ku, Nagoya City, Aichi Prefecture No. 60 Mitsubishi Rayon Co., Ltd. Product Development Research Center (72) Inventor Kazuya Goto 1-60 Sunadabashi 4-chome, Higashi-ku, Nagoya City, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Laboratory (72) Inventor Takashi Tada Nagoya City, Aichi Prefecture 4-61-60, Sunadabashi, Ward Mitsubishi Rayon Co., Ltd. Product Development Laboratory Inspector Yoshihide Kawakami (56) References JP-A-3-221414 (JP, A) JP-A-3-221413 (JP, A) JP-A-3-221412 (JP, A) JP-A-3-292111 (JP, A) JP-A-3-292110 (JP, A) JP JP-A-2-32843 (JP, A) JP-A-3-253309 (JP, A) JP-A-1-171852 (JP, A) JP-A-51-126260 (JP, A) A) The Polymer Society of Japan, edited by Toshio Kotogi et al., “New Polymer OnePoint 9, High Strength and High Modulus Fiber,” May 20, 1988, first edition, pages 2-4, page 46, Kyoritsu Shuppan (58) Field (Int.Cl. ⁷ , DB name) C08J 5/24 C08J 5/04-5/10 B29B 11/16

Claims (4)

(57) [Claims] (A) a reinforcing fiber having an elastic modulus of 200 GPa or more; (B) a fibrous thermoplastic resin having an elastic modulus of 100 GPa or less; (C) a polyfunctional maleimide (I) and a polyfunctional cyanate ester or an oligomer thereof ( In a prepreg for a fiber-reinforced composite material comprising a matrix resin containing a mixture of II) or a pre-reacted product of (I) and (II) as a main component,
A prepreg characterized in that the ratio of each of the components (A), (B) and (C) is within the following range, and the fibrous thermoplastic resin of (B) is present on the outer surface thereof. (A) / (C) = 60 / 40-75 / 25 (weight ratio) (B) / (C) = 0.5 / 100-40 / 100 (weight ratio) 2. 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. 3. The prepreg according to claim 1, wherein (B) is a mono- or multi-filament of a thermoplastic resin. 4. The prepreg according to claim 1, wherein the fibrous thermoplastic resin (B) is embedded in the outer surface thereof at a certain interval in one direction.