JPH04216923A - Manufacture of light-weight composite molded form and intermediate blank thereof - Google Patents

Abstract

PURPOSE:To manufacture the above light-weight composite molded form with a porous core having sufficient strength. CONSTITUTION:A reinforcing fiber knitted in three dimensions is impregnated with a foamable resin composition and pressed, inserted into a mold and heated and foamed, thus manufacturing a light-weight composite molded form. An article, in which the reinforcing fiber woven in two dimensions is impregnated with a nonintumescent resin, or a three-dimensional knit, in which a resin sheet, a fiber-reinforced resin sheet, etc., and a foamable resin composition are impregnated and pressed, are laminated and inserted into the mold and molded at that time, thus acquiring a sandwich material.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a lightweight composite molded product mainly consisting of a porous core, which has been widely used in recent years, and an intermediate material therefor.

0002

[Prior Art] Molded products mainly consisting of porous cores can be used as lightweight materials as they are or in combination with other materials.
For example, in recent years it has been widely used as a sandwich material in aerospace materials, sporting goods, and other fields.

[0003] Such porous molded products are usually a type of resin molded products in industrial terms. Conventionally, this has been industrially molded using foamable resin, that is, foam molded. This method can be broadly divided into molding a resin or its raw material that foams when heated or depressurized, or molding a specific resin into particles (primary foam).
There is a method in which this is placed in a mold and further expanded (secondary foaming).

[0004] In order to make this into a composite lightweight structure such as a sandwich material, the foam molded product is pasted with a skin material such as a pre-formed fiber reinforced resin (hereinafter abbreviated as FRP as necessary); Usually, a foam molded product is covered with a prepreg or the like and then molded, or a foamable resin is injected into a previously molded hollow outer shell to perform foam molding. recent years,
As improvements to these methods, methods have also been proposed, such as internal pressure molding using foam expansion and methods using a thermally expandable molded product as the material for the porous body (for example, Japanese Patent Application Laid-Open No. 1-255530).
No., Japanese Patent Application No. 1-179830, Japanese Unexamined Patent Publication No. 1622-1983
No. 07). As a method that further improves these methods, the present inventors previously proposed a method for molding a sandwich material having a porous core using thermally expandable particles and a liquid curable resin, and a method for creating an intermediate material therefor. .

Although these methods are preferred, another problem common to foam molded products is the brittleness of the molded products. That is, molded products that have expanded and become lighter in weight generally lack strength and cannot necessarily be said to have sufficient properties as a material. As a solution to this problem, for example, using glass beads in the porous core (
JP-A-52-21070, JP-A-63-202633
etc.) or by mixing short fibers (Japanese Patent Application Laid-open No. 60-23585).
Attempts have been made to improve the strength of the steel (e.g., Japanese Patent Application Laid-Open No. 61-20717), but the effects are not necessarily sufficient.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for easily and advantageously obtaining a foam molded product reinforced with long fibers and a sandwich material whose core is reinforced with long fibers, and a method useful for carrying out this method. The aim is to provide a suitable intermediate material.

[0007]

[Means for Solving the Problem] As a result of research on the above-mentioned problems, the present inventors have developed a lightweight molded product reinforced with long fibers, which is said to have particularly excellent reinforcing effects, that is, a foam reinforced with long fibers. We have invented a method for obtaining a molded product, a sandwich material whose core (foam core) is reinforced with long fibers, and an intermediate material for the same.

That is, according to the present invention, there is provided a method of impregnating a three-dimensionally knitted long fiber reinforcing material with a foamable resin composition, squeezing it, placing it in a mold, heating it, and performing foam molding. At this time, a sandwich material can be obtained by laminating and molding two-dimensionally woven reinforcing fibers or resin sheets impregnated with resin.

The main feature of the method of the present invention is that a three-dimensional knitted fabric made of reinforcing fibers is impregnated with a foamable resin composition,
After squeezing this, it is put into a mold and heated and foam-molded within the mold. The reason why three-dimensional knitting is used for foam molding is that when the resin composition expands and deforms,
The reinforcing fibers follow this and deform to fit into a predetermined reinforcing position, and if these reinforcing fibers are made into a woven fabric or two-dimensional knitted fabric, the conformability of the shape to the molded product will be poor. The use of a foamable resin composition is necessary in order to transform the resin together with reinforcing fibers into a predetermined shape, and the shape of the molded product is determined by the shape of the mold cavity. During molding, the resin composition foams and expands. Therefore, the mold must have a resin discharge facility or leave room for the resin to foam and expand. Note that the term "mold" as used herein refers to molds for molding, and is not limited to metal molds. Eliminate resin discharge or
The three-dimensional knitted fabric impregnated with resin is subjected to some degree of compression in order to at least suppress the amount of discharge. The heating temperature after putting it into the mold needs to be higher than the foaming temperature of the foaming material, which will be described later. Thus, the method of the present invention uses an intermediate material obtained by impregnating a three-dimensional knitted fabric with a foamable resin composition and pressing it.

[0010] The three-dimensional knitted material, which is the main element constituting the present invention, may be either organic long fibers or inorganic long fibers. Examples of organic long fibers include polyesters, polyamides, especially arylates and aramids, polyolefins, especially high modulus polyolefins, and other industrial fibers. Examples of inorganic long fibers include carbon fibers, glass fibers, silicon carbide fibers, and silicon nitride fibers. , alumina fiber, etc. In recent years, glass fibers particularly suitable for knitting have been developed, making the method of the present invention increasingly useful.

Various techniques have been published regarding three-dimensional knitting and its manufacturing method, and various methods can be selected from these according to the fiber. Although the present invention is not limited to the type or method of three-dimensional knitting, relatively tight knitting is preferred.

On the other hand, the resin constituting the foamable resin composition may be either a thermosetting resin or a thermoplastic resin. As the thermosetting resin, uncured or semi-cured resins such as unsaturated polyester resins, epoxy resins, and vinyl ester resins are particularly preferably used, and as the thermoplastic resins, polyolefin resins, polyamide resins, polycarbonate resins, polyester resins, and polyurethane resins are used. etc.

The foaming material used together with the above resin to form the foamable resin composition is not particularly limited, and is selected depending on the resin used. As the foaming material, expandable particles such as "Expancel" 461 manufactured by Expancel Co., Ltd.
, 551, "Matsumoto Microspheres" F-30D, F-50D from Matsumoto Yushi Pharmaceutical Co., Ltd., "Eslen Beads" HE from Sekisui Plastics Co., Ltd., etc., and organic blowing agents such as azodicarbonamide, azodiisobutyronitrile, dinitrile, etc. Pentamethylenetetramine, paratoluenesulfonylhydrazide, 4,4'-oxybisbenzenesulfonylhydrazide, etc., and inorganic blowing agents such as sodium hydrogen carbonate are used. In the case of a foaming agent, a foaming aid may be used in combination, if necessary.

In the present invention, a material obtained by impregnating a two-dimensional reinforcing fiber fabric with a resin can also be used by laminating it on the three-dimensional knitted fabric impregnated with the above-mentioned foamable resin composition. In this case, the reinforcing fibers may be either organic long fibers or inorganic long fibers as in the case of three-dimensional knitted fabrics. Such reinforcing fibers include polyesters, polyamides, especially arylates and aramids, polyolefins, especially high modulus polyolefins, other industrial fibers as organic fibers, carbon fibers, glass fibers, silicon carbide fibers, silicon nitride fibers, alumina fibers. etc. are mentioned as inorganic fibers. The resin impregnated into this may similarly be either a thermosetting resin or a thermoplastic resin. As the thermosetting resin, uncured or semi-cured resins such as unsaturated polyester resins, epoxy resins, and vinyl ester resins are particularly preferably used, and as the thermoplastic resins, polyolefin resins, polyamide resins, polycarbonate resins, polyester resins, and polyurethane resins are used. etc.

Furthermore, in the present invention, a resin sheet and/or a fiber-reinforced resin sheet can be used by laminating a three-dimensional knitted fabric impregnated with a foamable resin composition and pressed. In this case, either a thermosetting resin or a thermoplastic resin can be used as the resin. In the case of thermosetting resins, semi-cured ones are used, such as unsaturated polyester resins,
Semi-cured resins such as epoxy resins and vinyl ester resins are particularly preferably used. Thermoplastic resins include polyolefin resin, polyamide resin, polycarbonate resin,
Polyester resin, polyurethane resin, etc. are used. In the case of a fiber-reinforced sheet, reinforcing short fibers such as glass fibers, carbon fibers, silicon carbide fibers, alumina, short cut fibers of silicon nitride fibers, milled fibers, carbon, silicon carbide, silicon nitride, alumina, etc. Examples include those reinforced with whiskers or the like.

[0016]

EXAMPLES Next, the present invention will be explained in detail with reference to Examples. These are for the purpose of illustrating the invention and are not intended to limit the scope of the invention. In the following examples, parts are parts by weight unless otherwise specified.

[0017]

[Example 1] A mold was made from an aluminum plate and a Teflon spacer. The thickness of the spacer was 10 mm. A nozzle was provided at the end of the aluminum plate, and a valve was attached to this.

A three-dimensional knit preform 5gageinterlock, which is being sold on a trial basis by Teijin Ltd., was prepared. This preform was cut to fit a previously prepared mold.

100 parts of epoxy resin "Epicote 807" manufactured by Yuka Shell Co., Ltd. and 31 parts of "Epomate YLH006" were mixed, and further 5 parts of azobisisobutyronitrile were added. This is used as a foamable resin composition.

[0020] The three-dimensional knit preform was immersed in the above foamable resin composition to fully impregnate it with the resin composition. This was lightly squeezed using a press to reduce the amount of resin.

[0021] This resin-impregnated preform is placed in a mold,
The mold was placed in a hot bath at 80°C, and after 1 minute, the nozzle valve of the mold was opened to discharge the resin. The valve was closed when the discharge almost stopped.

After one hour, the mold was removed from the hot bath, cooled, opened, and the molded product was taken out. The obtained molded product was a porous molded product reinforced with long fiber knitting and had an apparent specific gravity of 0.85.

[0023]

Example 2 The mold, epoxy resin mixture, and three-dimensional preform used in Example 1 were prepared. In addition, expandable particles "Matsumoto Microsphere F-30D" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd. were prepared. Hereinafter, this will be abbreviated as F-30D.

Epoxy resin mixture 10 used in Example 1
F-30D was mixed with 0 parts and 10 parts. This will be referred to as resin mixture A.

[0025] A three-dimensional preform was cut out to fit the mold, immersed in resin mixture A to impregnate it, and then lightly squeezed. Place this in a mold and place it in a silicone oil bath at 80°C.
It was removed from the oil bath after about 1 hour. At this time, excess resin was discharged from the nozzle of the mold. However, the nozzle closed halfway. After cooling, the mold was opened and the molded product was taken out. The moldings obtained had good appearance and a reasonable density. The specific gravity of the molded product was approximately 0.87.

[0026]

[Example 3] Similar to Example 2, expandable particles "Matsumoto Microsphere F-30D" manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.
prepared. Hereinafter, it will be abbreviated as F-30D.

The mold and epoxy resin mixture used in Example 1 were prepared. However, the spacer of the mold was 5 mm. The epoxy resin mixture is 100 parts of epoxy resin "Epicote 807" manufactured by Yuka Shell and "Epomate YLH".
006'' was mixed with 31 parts.

In addition, glass cloth (MS253-1040-2NT-10FS manufactured by Asahi Fiberglass Co., Ltd.) and polyester nonwoven fabric “Unicel BT040” manufactured by Unicell Co., Ltd.
4" was prepared.

10 parts to 100 parts of the above epoxy resin mixture
F-30D was mixed in the proportion of 1.5 parts. Add this to resin mixture A
shall be.

[0030] A three-dimensional knit preform 5 gage 1 x 1 rib, which is sold on a trial basis by Teijin Ltd., was prepared, and this preform was cut into a mold prepared in advance.

The preform was immersed in resin mixture A to impregnate it. Both sides of this sheet are covered with non-woven fabric “UNICELL BT04”.
04" and epoxy resin ("Epicoat 807" 1
A glass cloth (MS253-1040-2NT-10FS manufactured by Asahi Fiberglass) coated with a resin containing 00 parts of Epomate YLH006 and 31 parts of Epomate YLH006 was placed on top of the other and placed in a mold.

[0032] The mold was closed and placed in a silicone oil bath at 80°C, and removed from the silicone oil bath after about 1 hour. On this occasion,
Excess resin was drained from the nozzle. However, the nozzle closed halfway. After cooling, the mold was opened and the molded product was taken out. The obtained molded product had a side-itch structure with a porous core, good appearance, and appropriate strength. The specific gravity of the molded product is approximately 0.97, and the bending strength is 14.2 kg/m.
m2, and the elastic modulus was 757 kg/mm2. The glass fraction of the molded product was 33% by weight, and the calculated ratio of resin to spaces (bubbles) was 50/50.

[0033]

[Example 4] Expanded particles "Expancel DU461" manufactured by Expancel were prepared. From now on, refer to this as DU461
It is abbreviated as. Furthermore, the same mold and epoxy resin mixture used in Example 3 were prepared. The spacer of this mold is 5 mm. The epoxy resin mixture was a mixture of 100 parts of epoxy resin "Epicote 807" manufactured by Yuka Shell Co., Ltd. and 31 parts of "Epomate YLH006". Furthermore, carbon fiber cloth (C06343B manufactured by Toray Industries, Inc., basis weight approximately 200 g/m2) and polyester nonwoven fabric (nonwoven fabric "Unicell BT0908" manufactured by Unicell Co., Ltd.) were prepared.

10 parts to 100 parts of the above epoxy resin mixture
DU461 was mixed in the proportion of 1.5 parts. Add this to resin mixture A
shall be.

[0035] On the other hand, a knit preform 5gage 1 x 1 rib, which is sold on a trial basis by Teijin Ltd., was prepared, and this preform was cut to fit a mold prepared in advance.

The preform was immersed in resin mixture A to impregnate it. Both sides of this sheet are covered with Unicel Co., Ltd.'s nonwoven fabric.
Unicell BT0908" and resin ("Epicote 8
Carbon fiber cloth (Toray C0
6343B) were stacked and placed in a mold.

The mold was closed and placed in a silicone oil bath at 100°C, and removed from the oil bath after about 1 hour. At this time, excess resin was discharged from the nozzle of the mold. However, the nozzle closed halfway.

After cooling, the mold was opened and the molded product was taken out. The molded product obtained had a good appearance and appropriate strength. Specific gravity is approximately 0.98, bending strength is 14.7kg/mm
2, the elastic modulus was 1230 kg/mm2.

[0039]

According to the method of the present invention as described above, a lightweight composite molded article having a porous core reinforced with long fibers can be produced in substantially one step. The resulting molded product exhibits excellent physical properties and can be widely applied to various structural materials, sporting goods, and parts for vehicles and aerospace.

Claims (5)

[Claims] Claim 1: Three-dimensionally knitted reinforcing fibers are impregnated with a foamable resin composition, compressed, and then inserted into a mold,
A method for producing a lightweight composite molded article, which is characterized by molding by heating, foaming, and expanding. Claim 2: Two-dimensionally woven reinforcing fibers are impregnated with non-foamable resin, and this is laminated with three-dimensionally knitted reinforcing fibers impregnated with a foamable resin composition and compressed. 2. The method of manufacturing a lightweight composite molded article according to claim 1, wherein the lightweight composite molded article is molded by inserting the article into a mold and heating, foaming and expanding the article. Claim 3: After laminating a resin sheet and/or fiber-reinforced resin sheet and three-dimensionally knitted reinforcing fibers impregnated with a foamable resin composition and compressed, the laminated sheet is inserted into a mold and heated. 2. The method for producing a lightweight composite molded article according to claim 1, wherein the molding is carried out by foaming and expanding. 4. An intermediate material for foam molding, characterized in that three-dimensionally woven reinforcing fibers are impregnated with a foamable resin composition and then compressed. 5. The intermediate material for foam molding according to claim 4, wherein the three-dimensionally knitted reinforcing fibers are knitted glass fibers.