JPH01171852A - Composite of prepreg for fiber reinforced composite material - Google Patents

Abstract

PURPOSE:To improve the adhesiveness or wettability with a resin matrix, by setting the wt. of a surface treated aromatic polyamide long fiber to the specific content of the whole of a prepreg sheet. CONSTITUTION:A monoaxially oriented prepreg sheet containing 125g/m<2> of a carbon fiber and a monoaxially oriented prepreg sheet containing 15g/m<2> of the carbon fiber are superposed so as to cross the fiber directions of both of them at a right angle and wound around a metal core rod three times so that the prepreg sheet containing 15g/m<2> of the fiber is set to the inside and the fiber directions are 90 deg. with respect to the longitudinal direction of the core rod. A monoaxially oriented prepreg sheet containing a surface treated aramid fiber in an amount of 2-20% by wt. of the whole is further wound around the prepreg layer two times so that the fiber direction thereof is same to the longitudinal direction of a mandrel. After the whole of the prepreg layer is tightened by a polyester shrink tape, the whole is heated and cured at 100 deg.C for one hr and subsequently at 120 deg.C for one hr. By this method, the merits possesses by the inorg. fiber prepreg sheets can be effectively utilized and the detects of said sheets can be compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a fiber-reinforced composite prepreg sheet, and particularly to a structure in which a plurality of types of prepreg sheets are combined.

<Conventional technology> In recent years, fiber-reinforced resin (FRP) has been widely used in many industrial fields such as the aerospace industry and the transportation machinery industry, as well as in consumer fields such as sports and leisure. is expanding even further.

FRP varies in shape, molding method, and type and size of fibers used depending on the application, but development is progressing to make it even lighter and higher in performance.

In order to improve performance, it is possible to use a combination of different types of fibers. For example, Japanese Patent Application Laid-Open No. 58-205755 describes a method in which carbon fiber threads and fiber threads of other types are placed adjacent to each other in the width direction. Arrayed hybrid prepregs are disclosed.

JP-A-58-57437 discloses a laminate in which a honeycomb is sandwiched between a carbon fiber prepreg sheet and an aromatic polyamide fiber prepreg sheet.

<Problems to be solved by the invention> JP-A-58-205755 and JP-A-58-574
In prepreg sheets and laminates thereof, such as those disclosed in Japanese Patent No. 37, in which carbon fibers are simply combined with fibers of different types, the drawbacks of carbon fibers are improved, but the characteristics of high rigidity and high elasticity are lost.

(Means for Solving the Problems) The present invention provides a prepreg sheet for inorganic long fiber reinforced composite materials (hereinafter referred to as inorganic fiber prepreg sheet) and a prepreg sheet for aromatic polyamide long fiber reinforced composite materials (hereinafter referred to as inorganic fiber prepreg sheet).
(hereinafter referred to as aromatic polyamide fiber prepreg sheet)
A fiber-reinforced composite, characterized in that the aromatic polyamide long fibers have been surface-treated, and the basis weight of the aromatic polyamide long fibers is 2 to 20% by weight of the whole. This is a prepreg composite for materials.

The inorganic fiber prepreg sheet used in the present invention is a prepreg sheet made of well-known inorganic fibers and a matrix resin.

Examples of inorganic fibers include carbon fibers, graphite fibers; ceramic fibers such as boron fibers, silicon carbide fibers, alumina fibers, and glass fibers; metal fibers such as stainless steel fibers, tungsten fibers, and molybdenum fibers; one type or There are two or more types.

These fibers can be used as they are, as they are usually reprinted.

As an example, carbon fiber is Magnamite AS-4, I
M-6 (manufactured by Sumika Vercules ■), microglass roving (Japan Glass Sen m@) as glass fiber, boron fiber (manufactured by AVCO, vacuum metallurgical ■), silicon carbide fiber (Japan Carbon side type), alumina Fibers (manufactured by Sumitomo Chemical Co., Ltd.) Examples of stainless steel fibers include Naslon@ (manufactured by Nihon Dansen).

The forms of these long fibers are continuous unidirectional tows, yarns and woven fabrics.

This form is selected depending on the use of the prepreg composite.

When the prepreg composite is a long object such as a tubular body and requires directional properties, that is, when bending strength is required in the longitudinal direction, tows and yarns aligned in one direction are used. If the prepreg composite is a plate-like material and requires homogeneous physical properties, a woven fabric may be used.

Matrix resins forming the prepreg sheet include epoxy resin, phenol resin, alkyd resin, urea-formaldehyde resin, melamine-formaldehyde resin, unsaturated polyester resin, aromatic polyamide resin, polyamide-imide resin, polyester-imide resin, and polyimide. Resin, thermosetting resin such as polybenzothiazole resin, silicone resin, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, polyvinyl chloride, ABS resin, styrene-acrylonitrile copolymer, polyamide, polyacetal, polysulfone, polycarbonate, polycarbonate Enylene oxide,
Thermoplastic resins such as polyether sulfone and polyether ether ketone, polybutadiene, polyisoprene,
Polychloroprene, styrene-butadiene copolymer (S
BR), acrylonitrile-butadiene copolymer (NB
R) Synthetic rubbers such as silicone rubber and natural rubber can be mentioned.

Note that the thermosetting resin is mixed with a known curing agent and curing accelerator suitable for the resin.

Among these, epoxy resins, unsaturated polyesters, polysulfones, polyethersulfones, polyetheretherketones, and polyimides are preferred.

Methods for producing inorganic fiber prepreg sheets are also well known.

That is, a sheet-like fiber tow drawn in one direction, a method of impregnating a sheet-like woven fabric with a resin solution, a method of impregnating a resin melt with a solvent and drying it, a sheet-like fiber resin membrane drawn in one direction, a method of applying pressure, etc. There is a method of heating and impregnating.

The fiber basis weight of the prepreg sheet is determined depending on the use of the prepreg composite, but is generally about 60 to 300 g/rd.

The resin content is approximately 25-50% by weight.

It is also possible to create an image by overlapping prepreg sheets with different fiber directions, or by combining short fibers such as chopped strands and whiskers. good.

In addition, when using multiple types of fibers, when aligning the fibers in one direction or making them into a woven fabric, it is possible to mix them in advance to make a prepreg sheet or create an intralayer type prepreg, or to use different types of fibers. Any method may be used, such as forming a glabellar-shaped prepreg by overlapping prepreg sheets and integrating them.

The aromatic polyamide long fibers used in the present invention include:
It is a long fiber of polyphenylene terephthalamide, and commercially available products include Kevlar (manufactured by DuPont) and Twaron (manufactured by DuPont).
Nippon Aramid Co., Ltd.) Technora (manufactured by Teijin) and other commonly known aramid fibers.

The surface treatment of aromatic polyamide long fibers to increase their affinity with the matrix resin includes well-known methods such as corona treatment, low-temperature plasma treatment, chemical etching, and brimer treatment. Preferred is a method of coating and curing the surface of the fibers with a brimer consisting of an epoxy compound and its curing agent as described in the publication.

As the epoxy compound, diglycidyl ether of glycerol is preferred; as the curing agent, amines, especially piperazine, are preferred; furthermore, as the composition of the brimer, imidazole, ethylene glycol, dicyamindiamide, and 2.4.6-)lith( Contains curing accelerators such as (dimethylaminomethyl)phenol.

Brimer is applied in an amount of 0.3 to 1 part by weight per 100 parts by weight of fibers.

After application of the brimer, it is dried at 130-250°C and subsequently hardened at 150-300°C.

Drying and curing are carried out using conventional methods and equipment, e.g. heated drums,
heat plate, heat roll, heating gas, steam box,
An infrared heater or the like is used.

If necessary, apply a finish such as polyglycol ester of oleic acid.

The finish may be applied at the same time as the brimer, or after the brimer has been applied, uncured or after it has been cured.

In order to make a prepreg sheet from the surface-treated aromatic polyamide long fibers, first, the long fibers are stretched in one direction and spread flat, or a woven fabric is prepared, and the above-mentioned matrix resin is applied to this by the above-mentioned method. Impregnate.

Since the weight of the aromatic polyamide long fibers in the prepreg composite of the present invention is relatively low at 2 to 20% by weight, the prepreg sheet of aromatic polyamide long fibers also has a small fiber weight, for example, 5 to 55 g/rd. It is preferable to make it somewhat thin.

To make this thin material, use thinner fibers,
A method of widening the fibers to make them thinner when aligning them, such as the method described in JP-A-60-11315, is applicable.

In addition, to make a thin prepreg sheet, a film of stretchable thermoplastic resin such as polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, etc. is coated on both sides of a prepreg sheet of unidirectionally aligned fibers produced by a known method. There is also a method of applying these thermoplastic resin film stretching methods to thin the prepreg sheet by stretching it in a direction perpendicular to the fiber direction of the prepreg sheet.

The combination of both prepreg sheets is made by combining one or more of both prepreg sheets in any number in any order to form a prepreg composite.

The overall thickness and shape can be determined depending on the industrial field and purpose of use, but if the fiber weight of the prepreg composite is small, the impact resistance will not be sufficient, and if there is too much, the inorganic Since the high bending strength and high elasticity of the fibers are no longer expressed, it is approximately 2 to 20% by weight, or 5 to 15% by weight, more preferably 5 to 15% by weight.
It is about 10% by weight.

Both matrix resins are preferably the same or of the same quality in terms of adhesion.

The method of combining and integrating an inorganic fiber prepreg sheet and an aromatic polyamide fiber prepreg sheet is as follows:
The best practice is to bring both matrix resins into close contact at a temperature that causes them to become sticky.

When making a prepreg composite into a flat plate, there is a method, for example, of stacking both prepreg sheets, passing them through a press roll heated to 30 to 100°C, and applying a linear pressure of several kg/cts.

As an example of forming a tubular prepreg composite from both prepreg sheets, both prepreg sheets are first cut out to a required size.

Both cut prepreg sheets are wrapped around a mandrel in the desired order on a horizontal table, then tightly wrapped with polyester, polypropylene or nylon shrink tape, and then crimped by heating in a hot air oven, etc. After hardening, the mandrel is pulled out using a hydraulic de-coring machine to form a tubular body.

<Effects of the Invention> According to the method of the present invention, it is possible to provide a prepreg sheet composite that fully takes advantage of the characteristics of aromatic polyamide fibers.

That is, by using aromatic polyamide fibers that have undergone special surface treatment according to the present invention, it is possible to improve adhesion and wettability with the resin matrix, and carbon fibers with high elastic modulus but low impact resistance can be improved. It is possible to compensate for the disadvantages of inorganic fiber prepreg sheets while maintaining their advantages.

<Example> Next, the present invention will be described in more detail, but the present invention is not limited thereto.

In the examples shown below, the total weight of fibers in the prepreg composites was the same.

The resins contained in the prepreg sheets used were all the same mixed epoxy resin, with the composition of 60 parts by weight of Sumiepoxy ELA-134 (manufactured by Sumitomo Chemical, bisphenol A type epoxy resin) and Sumiepoxy ES.
A mixture of 40 parts by weight of CN-220H (manufactured by Sumitomo Chemical, cresol novolac type epoxy resin), 5 parts by weight of dicyandiamide as a curing agent, and 1°1 of 3-(3,4-dichlorophenyl)-1 as a curing accelerator. - 4 parts by weight of dimethylurea was used.

As the inorganic fiber prepreg sheet, carbon fiber IM6
(manufactured by Vercules Co., Ltd., elastic modulus 30Ton/f12) was used by aligning it to one side, the fiber basis weight was 15g/rrl, 12
5g/m, 135g/rd, each with a resin content of 36%.

For aramid fibers, 0.6 parts by weight of primer (dicrycidyl ether of glycerol,
A mixture of piperazine, imidazole, and ethylene glycol) and surface-treated with 0.5 parts by weight of oleic acid polyglycol ester were used by pulling them together in one direction, and the fiber basis weight was 15 g/rrr, and the resin content was 40 weight. % stuff.

Using aramid fibers that are not surface treated and aligned in one direction,
The fiber basis weight is 15g/I, 80g/I, and the resin content is 40% by weight.

Alumina fiber (manufactured by Sumitomo Chemical, diameter 15 microns)
The fiber weight is 15 g/cd, 8
0 g/rd, each with a resin content of 30 parts by weight.

Four-point bending strength, elastic modulus, and impact strength were measured as physical properties of the hybrid cylindrical molded body having an inner diameter of 10 mm produced in this example.

In the 4-point bending test, the bending strength was measured from the load at the time of failure at a crosshead speed of 20 mm/min at a distance between fulcrums (long span) of 486 m and a path between load points (short span) of 162 m. A deflection curve was drawn and the flexural modulus was measured.

The impact strength was measured by cutting a cylindrical molded body into a length of 140fi.
J using Charpy impact tester with span 1201111
According to IS, K6911, the peak load was measured from the impact absorption energy required for failure without a notch and the impact failure behavior (load-time).

Example 1 Unidirectionally aligned prepreg sheet with fiber basis weight 125 g/rr+ of carbon fiber IM6 and fiber basis weight 1 of carbon fiber IM6
5 g/m unidirectionally aligned prepreg sheets are heat-pressed with the fiber direction perpendicular to 90 degrees, and then the prepreg sheet with a fiber basis weight of 15 g/rd is placed on the inside of a 10 mφ metal 8 rod (mandrel), and the fibers are It was wound three times in a direction 90 degrees from the length direction of the eight rods.

Furthermore, the fiber basis weight of the aramid fiber that has been surface-treated is 1
A 5 g/rd unidirectionally aligned prepreg sheet was wound twice so that the fiber direction was the same as the length direction of the mandrel.

Then, after wrapping it with polyester shrink tape, it was placed in a hot air oven at 100°C for 1 hour, then at 120°C.
A tubular molded product was obtained by heating for 1 hour and hardening.

The evaluation results are shown in Table 1.

Example 2 Instead of wrapping the unidirectional alignment prepreg sheet of surface-treated aramid fibers with a fiber basis weight of 15 g/rrr twice in Example 1, unidirectional alignment of surface-treated aramid fibers with a fiber basis weight of 15 g/rrr was performed. Except that a prepreg sheet and an alumina fiber prepreg sheet with a fiber basis weight of 15 g/rrr were laminated in the same fiber direction and wrapped once in the same fiber direction as the length direction of the mandrel.
The same procedure as in Example 1 was carried out.

The results are shown in Table 1.

Comparative Example 1 Instead of wrapping twice the unidirectionally aligned prepreg sheet of surface-treated aramid fibers with a fiber basis weight of 15 g/rrl in Example 1, a unidirectionally aligned prepreg sheet of untreated aramid fibers with a fiber basis weight of 15 g/m was used. The same procedure as in Example 2 was carried out except that the sheet was wrapped twice.

The evaluation results are shown in Table 1.

Comparative Example 2 1M6 unidirectionally aligned prepreg sheet with fiber basis weight 135g/i and fiber basis weight 15g/n? 1M6 unidirectionally aligned prepreg is laminated so that the fiber direction is perpendicular to 90 degrees. I wrapped it around.

Thereafter, tubular molding was performed in the same manner as in Example 1.

The evaluation results are shown in Table 1.

Claims (1)

[Claims] In a prepreg composite formed by combining a prepreg sheet for a fiber-reinforced composite material in which inorganic long fibers are aligned in one direction and a prepreg sheet for an aromatic polyamide long fiber-reinforced composite material, the aromatic polyamide long fibers are surface-treated. The basis weight of the aromatic polyamide long fibers is 2 to 20% of the total weight.
A prepreg composite for a fiber-reinforced composite material, characterized in that the content is 20% by weight.