JPH0232843A - Intermediate body of molded product and molded product - Google Patents

Abstract

PURPOSE:To obtain a molded product which has superior heat resistance, tenacity and shock resistance and which can suppress the spread of cracks at the shock, by forming said product by a fiber having a modulus of tensile elasticity within a specific range and attaching said product onto the surface of a thermosetting prepreg having reinforcing fibers specified in the range of weight as a base material or sandwiching said product between fiber reinforced resin laminations. CONSTITUTION:Such fiber is employed for the cloth that has the modulus of tensile elasticity not larger than 10,000kgf/mm<2>, preferably 5,000kgf/mm<2>. When the modulus of tensile elasticity exceeds 10,000kgf/mm<2>, the spread of cracks can be suppressed less effectively. Although the kind of the fiber is not restricted, particularly glass fiber or aromatic aramid fiber is suitable. The weight of the cloth is 21-25g/m<2>, preferably 5-10g/m<2>. If the weight is 25g/m<2> or more, the basic characteristic of the molded product is deteriorated. The reinforcing fiber is preferably a carbon fiber, glass fiber, aromatic polyamide fiber etc. having the ductility not smaller than 1.3%. Further, when it is applied to a composite that has the ductility not smaller than 4.0% after the composite employed for the prepreg is hardened, the composite becomes high in the level of shock resistance.

Description

Detailed Description of the Invention (Technical Field) The present invention provides an intermediate for producing a molded product having excellent impact resistance and the ability to suppress crack propagation upon impact, and
The present invention relates to the molded product.

The intermediate of the present invention can impart toughness to molded products without impairing the excellent mechanical and thermal properties of the matrix resin, especially when high-strength carbon fiber or the like is used as a reinforcing material. Furthermore, the molded product of the present invention obtained from this intermediate is suitably used as an aircraft structural material.

(Prior art and problems) In recent years, composite materials using carbon fibers, aromatic polyamide fibers, etc. as reinforcement materials have been developed by utilizing their high specific strength and specific stiffness.
It has been widely used as a structural material for aircraft etc.

These composite materials are often actually used after forming a prepreg, which is an intermediate product in which reinforcing fibers are impregnated with a matrix resin, through forming and processing steps such as heating and pressing.

As the matrix resin in prepreg, thermosetting resins such as epoxy resin, bismaleimide resin, unsaturated polyester resin, and polyimide resin are used, and recently, thermoplastic resins such as polyether ether kedone have also been used. Regardless of which resin is used, the composite material has excellent heat resistance,
It has been characterized by its mechanical properties, dimensional stability, chemical resistance, and weather resistance.

When a thermoplastic resin is used as a matrix resin, it is expected to have good heat resistance and mechanical properties as well as impact properties of the composite material, but it has poor handling properties as a prepreg, such as poor drapability of the prepreg. Therefore, it is a material that is difficult to handle with current molding technology, making it difficult to apply it to complex-shaped objects.

On the other hand, when a thermosetting resin such as an epoxy resin prepreg is used as a matrix resin, it is recognized that it shows good performance in terms of heat resistance and mechanical properties.
It has been pointed out that the toughness and impact resistance of composite materials are poor due to the low elongation and brittleness of the matrix resin, and improvements have been sought.

In particular, when composite materials made from these prepregs are used for aircraft-foam structural materials, they are resistant to external impacts such as pebbles being thrown up when leaving land and falling tools during leakage adjustment. Although it is necessary to have the ability to endure, it has been considered difficult to improve impact resistance without reducing heat resistance.

When trying to improve prepreg with impact resistance, ■
- Increasing the elongation of reinforcing materials such as carbon mH, ■ Increasing the toughness of the matrix resin used in prepreg,
■It has been pointed out that optimizing the reinforcing fiber/matrix resin interface is an important point and research has been progressing, but it is also important to control the higher-order structure of the FF4 layer material that is the molded product. It is thought to be important for improving properties and suppressing crack propagation.

A technique for improving the impact resistance of composite materials by increasing the toughness of the matrix resin for prepregs is disclosed in Japanese Patent Application Laid-Open No. 58-1.
20639@, No. 62-250021, No. 62-36
As is known from publications such as No. 421 and No. 62-57417, prepregs are made by blending a matrix resin with a specific elastomer component, a polymeric rubber component, and a thermoplastic resin to improve the toughness and WJ impact properties of the composite material. Compositions have also been developed, but the impact resistance of composite materials has not yet been satisfactory.

Regarding optimizing the interface of reinforced 131!11/matrix resin, research is being conducted on the surface treatment conditions of fibers and the selection of scales for sizing agents, but it is still at the research stage and it is difficult to achieve the desired effect. The current situation is that it has not been obtained.

Possible techniques for controlling the higher-order structure of a composite material and improving its impact resistance include a method of controlling the material form of reinforcing fibers, and a method of inserting different materials between laminated layers. Attempts have been made to use three-dimensional fabrics as reinforcing materials in order to create uniform materials, but so far,
There are many problems such as difficulty in fabrication, poor resin impregnation, and difficulty in controlling the fiber volume content, and so it has not been able to demonstrate any significant effects in practical use.

Regarding the technology of inserting different materials between the feR spaces of composite materials, Japanese Patent Application Laid-open Nos. 51-33162 and 61-13571
As shown in Publication No. 2, a material in which a scrim cloth is laminated on the surface of a prepreg is known, but the scrim cloth in this case actually prevents horizontal cracking of the prepreg and fiber disorder. It is used for reinforcing purposes of prepreg itself.

% of the composite material by inserting dissimilar materials between the composite material stacks.
JP-A-60-632 as a technology to improve I attack characteristics.
There is an interleaf technique as shown in the publications No. 29 and No. 60-231738.

As an interleaf material, the thickness is 0.03 to 0.06
It is common to use a highly flexible epoxy resin layer with a thickness of 0.01 to 0.05 mm, for example, a film of polyetherimide, polyether sulfone, or polyether ether ketone. It is also possible to use thermoplastic resin films such as.

When using an epoxy resin with excellent flexibility as an interleaf material, for example, an engineered boxy resin layer with a high elastomer component, it is necessary to incorporate a large amount of elastomer component in order to improve the impact properties. Depending on the type and type of elastomer component, the heat resistance and mechanical properties of the composite material may be lowered.Since restrictions are placed on the type and length of the elastomer component, sufficient effects are often not achieved.

When a thermoplastic resin film is inserted between the laminated layers of a composite material, the effect of improving the impact resistance of the composite material is recognized, but since the space between adjacent layers is completely covered by the resin film, There may be problems with the adhesion between the matrix resin and the thermoplastic resin film, or the WAmAm in-plane direction fat flow may be blocked, resulting in uneven resin flow, leading to deformation of the molded product, or the thermoplastic resin film may be damaged. Since the film is relatively thick, the volume ratio of the thermoplastic resin film to the matrix resin becomes high, which sometimes causes a corresponding deterioration in the performance of the composite material.

[Purpose of the invention]

The purpose of the present invention is to overcome the above-mentioned problems and provide excellent toughness and impact properties (III impact strength) in addition to excellent heat resistance.
T! ii! an intermediate (prepreg) that provides the composite material with a molding that has the ability to suppress crack propagation during
The object of the present invention is to provide the molded product. In prepreg using thermosetting matrix resin, a thin layer made of a material different from the matrix resin is provided on the surface of the prepreg, and the different material is inserted between the laminated layers of the composite material during molding. An object of the present invention is to provide a molded intermediate for a hot-melt type fiber-reinforced composite material that has excellent impact strength and the ability to suppress crack propagation during 'tis, and a molded product obtained therefrom.

(Structure of the Invention) The present invention is as described in the following claims (1) and Ir1 (2>).

(1) A tensile modulus of 10,000 k (lf
/II cloth weight 1-25g made from fibers of 12 or less/
An intermediate body of a fiber-reinforced resin laminate molded product formed by pasting the fabric of No. 112.

(2) A 4-layer fiber-reinforced resin molded product in which a woven fabric with a fiber date of 1 to 25 g/I' made from fibers with a tensile modulus of 10,000 kOf/ms' or less is interposed between the laminated layers.

Preferred real fMBs of the present invention are as follows.

(,1) The fiber-reinforced resin laminate molded intermediate according to claim (1), wherein charcoal *m#11 having an elongation of 1.3% or more is used as the reinforcing m-thread.

(b) The intermediate of the fiber-reinforced resin W 4-layer molded product according to claim (1), wherein the fibers forming the woven fabric adhered to the surface of the thermosetting resin prepreg have a melting point of 200°C or higher. body.

(C) The fiber-reinforced resin laminate molded intermediate according to claim 1, wherein the cured matrix resin used in the thermosetting resin prepreg has an elongation of 4.0% or more.

The molded product of the present invention has excellent Vfi impact strength and also has the property of making it difficult for cracks that occur to propagate.

In the present invention, fibers having a tensile modulus of elasticity of fibers of 10,000 kgf/lIm' or less, preferably 5,000 kof/gui' or less are used as the II cloth constituting the woven fabric. Tensile modulus of fiber is 10,000kgf
/■', the effect of suppressing crack propagation and improving impact properties is small. The type of fiber used is not limited, and may be either inorganic navy blue or organic fiber, and may be either natural polymer fiber or synthetic polymer fiber. In particular, glass fiber and aromatic aramid 1iua are preferably used.

These fibers may be used alone or in combination.

The form of the powder is not particularly limited, and filamentary, spun yarn, blended yarn, etc. are used. There is no particular limit to the twist of the thread, and the thickness of commercially available yarn is usually 20 to 50 mm.
The fibers with a diameter of 0μ are used, and the above-mentioned fibers are run on a loom in the form of single threads or twisted white threads, and processed into lt products.

Regarding the thermal properties of the fibers, since the thermosetting resin composition which is the matrix resin has a curing temperature of 100 to 200°C, it is desirable that the melting point of the substance constituting the fibers is 200°C or higher. In addition, in order to improve handleability or the compatibility of the thermosetting resin composition that is the matrix resin,
Physical treatment, chemical treatment, oil treatment, etc., which are generally used for each m1ii fiber, may be performed.

Examples of the type of fabric II include plain weave, twill weave, satin weave, and Karame weave. It is also possible to use a so-called mixed fabric, which is woven using different types of fibers.

The fiber basis weight (weight per 111th area) of the fabric is #! Since the snout will be inserted between the laminated sheets (composite), it is necessary to have a weight that does not impair the mechanical properties of the molded product.
/11', preferably 5 to 10 g/-2.

If the fiber basis weight is less than 19/m3, sufficient effect of improving impact properties cannot be exhibited;
If it exceeds +e', the basic properties such as tensile strength and compressive strength required for the molded product itself will be reduced.

Specific types of fibers used in the fabrics used in the present invention include cotton, silk, rayon, organic synthetic polymer fibers (
Fibers such as polyacrylonitrile, polyamide, polyester, polyetherimide, polyetheretherketone, aramid, polybenzimidazole, polyimide, etc.)
, glass fiber, aluminum fiber, etc., and several types of fabrics made of AI navy blue may be used together in one molded product.

The reinforcing fibers used in the present invention are preferably carbon fibers, glass fibers, aromatic polyamide fibers, etc. having an elongation of 1.3% or more. Usually glass fiber, aromatic polyamide 4I
I11 has an elongation of 2.5% or more. carbon uI
If II is used with an elongation of less than 1.3%, the impact properties of the composite material tend to be somewhat inadequate.

In particular, in the present invention, the effect is great when carbon fiber, especially high modulus carbon fiber, is used as the reinforcing material.

Carbon mm is not particularly limited, such as acrylic carbon fiber, pitch carbon fiber, etc., and has a tensile strength of 350 kgf/m.
m' and an elastic modulus of 24T/+am' are preferably used. A material that improves the mechanical properties of composite materials, has a tensile strength of 400 kgf/am' or more, and a modulus of elasticity of 30 T/v.
It is also possible to use a so-called medium elasticity high hardness carbon fiber having a w' level.

Intermediates (prepregs) based on these reinforced II miscellaneous materials are impregnated with an uncured thermosetting resin composition between the fibers of a base material such as a one-sided sheet of reinforcing fibers, a woven fabric, or a short IIA fiber mat. /C thing.

The thermosetting resin composition as the matrix resin is an epoxy resin, a bismaleimide resin, an unsaturated polyester resin, a polyimide resin, etc., and the content of the resin composition is 3
0 to 50% by volume is suitable. The present invention is also effective when the elongation of the matrix resin is improved due to resin modification or the like. If the fabric used in the present invention is applied to a prepreg made of a resin composition with high impact properties, the impact resistance of the composite will be further improved, and it will have the property of making it difficult to avoid the propagation of cracks that occur. In particular, when the woven fabric of the present invention is used between composite layers in which the cured elongation +a of the thermosetting resin composition used in the prepreg is 4.0% or more, the composite has a high level of box impact resistance. As a result, the scope of application to aircraft-substructure materials will be expanded.

The basic prepreg of the thermosetting resin composition can be manufactured by a conventionally known method.

The present invention will be explained with reference to the drawings.

FIG. 1 at J3 in the drawings shows a perspective view of the intermediate molded product of the present invention.

FIG. 2 shows examples (a), (b), and (c) of the texture of the fabric attached to the molded intermediate of the present invention.

FIG. 3 schematically shows a cross-sectional view of the molded product intermediate of the present invention.

In FIG. 1, 1 is a prepreg, and 2 is a woven fabric. The prepreg 1 is made by impregnating and retaining an uncured thermosetting resin between the fibers in a fiber sheet such as a unidirectional fiber sheet, a woven fabric, or a random mat.As the thermosetting resin, the above-mentioned epoxy resin, These include bismaleimide resin, unsaturated polyester resin, polyimide resin, etc.

Since the fabric 2 has through holes, the matrix resin 1-2 of the prepreg passes through the through holes 2-1 of the fabric 2 and wraps around the surface of the fabric to form a continuous layer.

Although the fabric 2 may be attached to both sides of the prepreg 1, it is usually attached only to one side.

When laminating the molded product intermediate of the present invention, it is not necessary that all the layers are composed of the molded intermediate of the present invention, but it can also be laminated in combination with a normal prepreg to which no woven fabric is attached. Such a molded product has excellent impact resistance and is less likely to cause peeling between laminated layers.

The solid in molded article of the present invention can be produced, for example, by the following method.

First, a prepreg is prepared by a conventional method such as a hot melt method or a solvent method, and then a fabric is combined with the prepreg and integrated by pressing with a plate, an O-ra, etc. At this time, heating can be performed, but the heating temperature is 6.
The temperature is preferably 0 to 120°C.

(Effects of the Invention) According to the present invention, the molded product intermediate and molded product (q) have excellent mechanical properties, thermal properties, and toughness, and also have characteristics that prevent cracks that occur from propagating. Therefore, it is suitably used for aircraft mechanism T1 materials, space structure materials, etc.

(Examples and Comparative Examples) Example 1 A carbon fiber unidirectional prepreg made of a resin composition not shown in Table 1 below was produced by a hot melt method.The carbon fiber (CF) used was Besphite [ M-500 (manufactured by Toho Rayon Co., Ltd., tensile strength 500 kgf/+es2, elastic modulus 30 T/mIm"). The CF basis weight of the prepreg was 150 g/*', and the resin content was 32%.

On the other hand, a plain weave with a fiber basis weight of 10 g/l 112 made from doubled polyether ether ketone fibers (abbreviated as PEEK fibers, tensile modulus of elasticity of about 600 kgf/as', melting point of 334°C) with an apparent thickness of about 80 μm. Prepared the fabric.

The prepreg and film were stacked and passed between hot rollers at 80° C. to seal them together to obtain a molded intermediate.

From this molded intermediate, a predetermined method and number of small pieces are cut, laminated, and molded in an autoclave at a heating rate of 2°C.
The resin was cured at 180°C for 2 hours to produce a molded plate. A test piece was cut out from this, 0° interlaminar shear strength, 0° compressive strength, 1500 in-lb/1n.
When the compressive strength after lj @ was measured, the results shown in Table 1 were obtained.

Comparative Example 1 A carbon fiber unidirectional prepreg made of the resin composition shown in Table 1 was produced in the same manner as in Example 1.

A molded plate was prepared under similar conditions from this prepreg to which no 4T fabric made of polyetheretherketone fibers was attached, and the molded plate was tested.

(Comparison of results) Although not shown in Table 1 and based on the physical properties, the molded plate of Example 1 has no strength difference in 0° WJ shear strength and 0° compressive strength compared to Comparative Example 1. ! i00 i n-1b /
In! It was revealed that the compressive strength after impact was high and the impact resistance was excellent.

Example 2 A carbon fiber-oriented prepreg made of the wood composition shown in Table 1'11 was made in the same manner as in Example 1, and a spun yarn with an apparent thickness of about 200 μm was used as a fabric to be attached to the prepreg. polyetherimide fiber (abbreviated as PEI, tensile modulus approximately 700 kgf/1111', glass rolling 1i
Fiber mesh (41Sg /+
Prepare the plain weave fabric of e', arrange it on the prepreg surface,
Both were pasted together by passing between hot rollers at 80°C to obtain a molded intermediate.

A molded plate was prepared from this molded intermediate in the same manner as in Example 1, and had a 0° interlaminar shear strength, 0° compressive strength, 1500
When the compressive strength of the in-1b/in impact model was measured, the results shown in Table 1 were 1 tP.

Comparative example 2 A prepreg was made in the same manner as in Example 2.

Molding was performed in the same manner using only this prepreg without attaching the fabric, and tests were conducted on the molded plates.

(Comparison of results) As shown in Table 1, the molded plate of Example 2 has no difference in 0° interlaminar shear strength and 0° compressive strength compared to Comparative Example 2, but -Ib /1nllj
It became clear that the compressive strength after 12 hours was high, and the VM impact resistance was affected.

Example 3 A carbon fiber unidirectional prepreg made of the resin composition shown in Table 1 was made in the same manner as in Example 1, and a doubled polyester yarn with an apparent thickness of about 100 μm was used as a fabric to be attached to the prepreg. Fiber (Tetron, tensile modulus 120
Prepare a plain weave fabric with a fiber basis weight of 20 (1/I') made from 0klJf/ms" (melting point 260°C), arrange it on the prepreg surface, pass it between 11-butler rollers at 80°C and stick both sides together to form a molded product. 1g of intermediate.

This molded intermediate was prepared for molding in the same manner as in ¥Zettai 1, and then RI! It was cured at 130° C. for 1.5 hours at a temperature of 2° C. to produce a molded plate. Shear strength between 0°WI for molded plate, 0
Compressive strength: 1500 in-1 b/in The compressive strength after impact was measured and the results are shown in Table 1 as 1!7.

Comparative example 3 A prepreg was made in the same manner as in Example 3.

Molding was performed in the same manner using only this prepreg without attaching the fabric, and tests were conducted on the molded plates.

(Comparison of Results) As shown in Table 1, the molded plate of Example 3 has no difference in 0° interlaminar shear strength and 0° compressive strength compared to Comparative Example 3, but It was revealed that the compressive strength after impact was high and the impact resistance was excellent.

Example 4 A carbon fiber-oriented prepreg made of the resin composition shown in Table 1 was made in the same manner as in Example 1, and a woven fabric with an apparent thickness of about 60 μm was prepared to be attached to the prepreg. Polyetherimide fiber N (abbreviation PEI, tensile modulus 700kof/+ua2, glass transition temperature 216°C)
A twill fabric with a mis area weight of 250/l' was prepared, and this fabric was arranged on the surface of the prepreg and passed between hot rollers at 80° C. to stick them together to obtain a molded intermediate. From this molded product intermediate, a molded plate was prepared in the same manner as in Example 1, and the shear strength at 0°, the compressive strength at 0°,
When the compressive strength after 1500in-lb/1nlj impact was assumed, the results shown in Table 1 were Ifjtζ.

Comparative example 4 A prepreg was made in the same manner as in Example 4.

Molding was performed in the same manner using only this prepreg without attaching the fabric, and tests were conducted on the molded plates.

(Comparison of results) As shown in Table 1, the molded plate of Example 4 has no strength difference in 0° layer sliding 1 shear strength and 0° compressive strength compared to Comparative Example 3. However, it was revealed that the compressive strength after 1500 in-Ib/in impact was high (and the impact resistance was excellent).

Examples 5 to 8 and Comparative Examples 5 to 8 Carbon fiber unidirectional prepregs were made in the same manner as in Example 1 using the resin compositions shown in Table 2, and fabrics shown in Table 2 (tensile modulus of 700kgf/s+m',
7000 kof/ln+' of glass fiber, about 7000 kaf/1 m2 of aramid IMII, and 7000 kgf/as' of aluminum fiber were arranged on the prepreg surface, and passed between hot rollers at 80°C to stick them together to obtain a molded intermediate. Ta.

From this molded product intermediate, a molded plate was prepared under molding conditions not shown in Table 2, and the molded plate had a 0° interlayer t! A/Strength,
The compressive strength of 0'' compressive strength and 1500 in-1b/in impact erosion were measured, and the results shown in Table 2 were obtained.

Moreover, in Comparative Examples 5 to 8, prepregs were made in the same manner as in Examples 5 to 8. Molding was performed in the same manner using only the prepreg without attaching the fabric, and tests were conducted on the molded plates.

(Comparison of results) As shown in Table 2, the molded plates of Examples 5 to 8 showed no strength differences in 0° interlaminar shear strength and O'' compressive strength compared to Comparative Examples 5 to 8. Although not, 1500in-1b /
It was found that the compressive strength after being hit by 1nW77J was n low, indicating that it had excellent impact resistance.

Notes to Table 1 (Note 1) * 1: Zero characteristics after 1500 in-lb/inm impact (using 32 Bly pseudo-isotropic laminate) Note 2) Araldite MY720. Tetraglycidylamine type epoxy resin (manufactured by Ciba Geigy) E LMioo: Triglycidylamine type epoxy resin (manufactured by Sumitomo Chemical) EPN-1138: Phenol/novolak type epoxy resin (manufactured by Ciba Geigy) Epicote 828: Bisphenol A type epoxy resin (manufactured by Ciba Geigy)
Epicoat 1001: Bisphenol A epoxy resin (manufactured by Yuka Shell) EPU-6: Urethane-modified epoxy resin (manufactured by Asahi Denka) DEN485: Phenol novolak epoxy resin (manufactured by Dow Chemical) CTBN Hiker 1300x13: Butadiene.

Crylonitrile rubber (manufactured by Ube Industries, Ltd.) (Note 3) PEI: Polyetherimide PE [EK: Polyether ether ketone Note to Table 2 (Note 1) * 1: 1500 in-lb / in% [Strength 11
217) 4i Wi pseudo-isotropic laminate used) (32 plastic (Note 2) BT-2160: Bismaleimide-triazine resin (
Matrimid 5292: Bismaleimide resin (manufactured by Ciba Geigy) Compimidel-1-800: Bismaleimide resin (manufactured by Shell Chemical) PMR15: Polyimide resin (manufactured by NASA, TRW) Epicoat 828: Bisphenol A type Epoxy resin(
manufactured by Yuka Shell Co., Ltd.) ELM-100: Trigcidylamine type epoxy resin (
(manufactured by Sumitomo Chemical Co., Ltd.) (Note 3) PEI: Polyetherimide (Note 4) Fiber volume content of molded product: 58-60% by volume

[Brief explanation of the drawing]

FIG. 1 shows a perspective view of an intermediate molded product of the present invention. Figures 1' and 12 show examples (a), (b), and (c) of the textile structure to be adhered to the molded intermediate of the present invention. FIG. 3 schematically shows a cross-sectional view of the molded product intermediate of the present invention. Explanation of symbols in the drawings 1 Nibbly preg, 1-1: fiber, 1-2: lil fat, 2
: Textile, 2- through hole patent applicant l! Kunishi - Yoshi Shushiki Company Representative Patent Attorney
Doi Part 3 Figure 2 Figure 1 (C) 5 pieces of horizontal Mikoori

Claims (2)

[Claims] (1) A tensile modulus of elasticity of 10,000 kgf/mm^2 is applied to the surface of a thermosetting resin prepreg based on reinforcing fibers.
A fiber-reinforced resin laminate molded intermediate product made by pasting a fabric with a fiber basis weight of 1 to 25 g/m^2 made from the following fibers. (2) A fiber-reinforced resin laminate molded product in which a woven fabric with a fiber basis weight of 1 to 25 g/m^2 made from fibers with a tensile modulus of elasticity of 10,000 kgf/mm^2 or less is interposed between the laminated layers.