JP2008290441A - Manufacturing method of sandwich material made of reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved method which does not cause non-impregnation of resin, provides stable quality and permits a light weight and low cost with respect to a manufacturing method of sandwich material made of reinforced plastic according to a vacuum injection molding method. <P>SOLUTION: In the improved method, a material 2 to be impregnated made by arranging a liquid-permeable reinforcing material on both surfaces of a liquid-permeable core part is impregnated with a liquid heat curable resin according to the vacuum injection molding method and, thereafter, is cured. A resin foamed body, a sheet-like body in which a through-hole is formed or a liquid-permeable sheet-like body in which granular material is filled is preferably used as the liquid-permeable core part. A fiber base material such as nonwoven fabric, short-fiber layered mat-like material and sheet-like material made of long fibers, cloth, woven fabric and nit fabric is preferably used as the liquid-permeable reinforcing material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a reinforced plastic sandwich material, and more particularly, to a vacuum injection molding method of a reinforced plastic sandwich material using an impregnated material in which a liquid-permeable reinforcing material is disposed on both surfaces of a core portion. It relates to an improved method.

  As a lightweight and high-strength material, fiber reinforced plastic (FRP) has attracted attention in various industrial fields, and among them, carbon fiber reinforced plastic is being frequently used due to its excellent mechanical properties and the like. Such fiber reinforced plastics are often molded by a conventional hand-up molding method.

However, this molding method is not preferable for producing a relatively large and thick molded article, and is too costly, and styrene and the like are volatilized during the production.
Therefore, in recent years, a vacuum injection molding method in which a resin is injected into a base material having a void made of a reinforcing fiber material under vacuum, for example, vacuum by vacuum suction, is being adopted as a basic technique. The material to be impregnated is placed on the mold, and further, a resin fluidized layer is provided through a release material, and a bag film covering the resin film is installed so that the periphery thereof can be sealed and vacuumed, A method for injecting and molding a resin into the bag film has been proposed (see, for example, Patent Document 1).

In this vacuum injection molding method, when a large-sized and thick molded product is to be produced, there are problems such as an excessive weight, a long time for resin impregnation, low productivity, and high cost.
In order to solve such problems, it is recalled that the core material is made of a lightweight material, for example, a resin foam, and a reinforced plastic material is arranged on both sides to make the sandwich material lightweight and strong. Is done.
However, in order to produce a sandwich material by the vacuum injection molding method, a resin fluidized layer is provided at the top in the process of impregnating the impregnated material with the resin, and the upper surface (the surface opposite to the mold) is The resin is easy to flow and impregnate, but the impregnated material on the lower surface placed on the mold is not provided with the resin fluidized layer, so the resin is difficult to impregnate and the resin non-impregnated part is generated Problems such as easy to do.

JP-A-60-83826

  In view of such problems, the object of the present invention is to provide a method for producing a sandwich material made of reinforced plastic by a vacuum injection molding method, exhibiting stable quality without unimpregnation of resin, and capable of reducing weight and cost. To provide a law.

  As a result of intensive studies to solve the above problems, the present inventors have arranged a liquid-permeable reinforcing material on both surfaces of the liquid-permeable core portion to obtain an impregnated material, which is subjected to a liquid heat treatment by a vacuum injection molding method. It has been found that impregnation with a curable resin and curing and molding contributes to solving the problem, and the present invention has been made based on this finding.

  That is, according to the first aspect of the present invention, a liquid thermosetting resin is applied to an impregnated article in which a liquid-permeable reinforcing material is disposed on both surfaces of a liquid-permeable core portion by a vacuum injection molding method. Provided is a method for producing a reinforced plastic sandwich material characterized in that it is impregnated and then cured.

  According to a second aspect of the present invention, there is provided the manufacturing method according to the first aspect, wherein the liquid-permeable core portion is made of a resin foam.

  Further, according to the third invention of the present invention, in the second invention, the resin foam is formed in a sheet shape and a large number of through holes are dispersed on the entire surface in the thickness direction on average. A manufacturing method is provided.

  According to the fourth invention of the present invention, in the first invention, the liquid-permeable core portion includes a plurality of resin foams, with the gaps being substantially parallel to each other, and the liquid-permeable reinforcing material. There is provided a manufacturing method characterized by being juxtaposed in between.

  According to a fifth aspect of the present invention, there is provided a production method characterized in that, in any one of the second to fourth aspects, the resin foam is an independent foam.

  According to a sixth aspect of the present invention, in the first aspect, the liquid-permeable core portion is made of a liquid-permeable sheet-like body filled with a granular material. Is provided.

  According to a seventh aspect of the present invention, there is provided the manufacturing method according to the sixth aspect, wherein the sheet-like body is a honeycomb sheet.

  According to an eighth aspect of the present invention, there is provided the manufacturing method according to any one of the first to seventh aspects, wherein the liquid-permeable reinforcing material is a fiber base material.

  According to the ninth invention of the present invention, in the eighth invention, the fiber base material is selected from the group consisting of a nonwoven fabric, a short fiber laminated mat, a sheet made of long fibers, a fabric, a woven fabric, and a knitted fabric. There is provided a production method characterized by at least one selected from the above.

  According to the method of the present invention, by making the core portion liquid-permeable, from the impregnated material on the upper surface where the liquid-permeable reinforcing material is disposed, through the hole in the core material, the gap in the core material, and the like. Thus, the resin can easily flow into and impregnate the material to be impregnated on the lower surface, and a remarkable effect is obtained that the resin non-impregnated portion of the material to be impregnated on the lower surface is less likely to occur.

  The reinforced plastic sandwich material molded by the method of the present invention is stable in strength because no resin-impregnated portion is generated, and moreover, when the core portion is made of a resin foam, it is more than a molded product of reinforced plastic alone. In addition, the amount of resin and fibers used is reduced, the cost is low, and the weight is reduced.Furthermore, when the core is a liquid-permeable sheet-like body in which a honeycomb sheet is filled with granules, The sheet material has advantages such as improved thickness accuracy, stable strength, and increased strength.

  In the method of the present invention, a liquid thermosetting resin is impregnated by a vacuum injection molding method on an impregnated material in which a liquid-permeable reinforcing material is disposed on both surfaces of a liquid-permeable core, and then cured. It is characterized by.

  As the liquid-permeable core, for example, a resin foam having a large number of sheet-like through holes dispersed on the entire surface in the thickness direction and a plurality of resin foams, or a plurality of resin foams, are substantially spaced from each other. Opened in parallel and juxtaposed between liquid-permeable reinforcing materials, in other words, the resin foam is cut into several members and arranged side by side so that the resin can permeate and flow in. Examples thereof include a liquid-permeable sheet-like body formed by filling a honeycomb core or a net-like bag with a granular material such as a small piece of sand, metal, inorganic material, plastic, or a pulverized product of industrial waste thereof.

The resin foam is preferably a closed foam having closed cells because the foam is not impregnated with resin and contributes to weight reduction. However, a resin foam having open cells can also be used.
As the resin foam, a foam of a thermoplastic resin such as polypropylene, polyethylene, polyethylene terephthalate, or polystyrene is preferable, and a foam of a thermosetting resin such as a phenol resin or a urethane resin is also used. The foaming ratio of the foam is preferably 5 to 30 times. If the expansion ratio is too high, the strength as a sandwich plate is insufficient, and if it is too low, the weight cannot be reduced.
When a sheet-like material having through holes is used as the resin foam, the through holes preferably have a hole diameter of 1 to 7 mm. If the pore diameter is too large, the amount of impregnated resin increases, and the weight cannot be reduced. If it is too small, the liquid resin does not pass easily. In the case of a small hole of about 1 mm, it is better to place a larger number of holes on the entire surface. In this way, the impregnation of the lower material to be impregnated becomes more uniform.
When a plurality of resin foams are juxtaposed, it is preferable that the individual resin foams are installed with a gap between them and arranged at a pitch of 100 mm to 400 mm. If this pitch is too wide, resin impregnation of the lower material to be impregnated is delayed, and if it is too narrow, weight reduction cannot be achieved. The gap is preferably 1 to 10 mm.
In addition, when using a liquid-permeable sheet-like material filled with a granular material, sand and the like can be obtained at low cost and can be expected to have a high strength as a sandwich plate by being impregnated with resin. As the granular material, those having an average particle diameter of 100 μm to 5 mm are preferable, and as the liquid-permeable sheet-like material, for example, a net-like material such as a net or a honeycomb sheet is preferable. The average particle size is determined based on the particle size distribution measured according to a conventional method using a laser diffraction type particle size distribution analyzer.
Also, filling the honeycomb sheet core with particles such as sand is a good means for improving the thickness accuracy of the core material.

As the liquid-permeable reinforcing material, a fiber base material is preferable. Among them, a nonwoven fabric, a short fiber laminated mat-like material, a sheet-like material made of long fibers, a fabric, a woven fabric, a knitted fabric, and the like can be given. Examples of the nonwoven fabric include carbon cloth and Kepler cloth, and chopped strand mats.
Other liquid-permeable reinforcing materials include metal-perforated metal with liquid permeability, aluminum mats, liquid-permeable panels with holes in inorganic materials, wood panels, and foams. Open-cell plastic materials can also be used.
These liquid-permeable reinforcing materials may be arranged in a stacked manner instead of a single body, or may be a laminate of different materials of a metal material and a plastic material.
In addition, a liquid-permeable sheet-like material filled with a granular material such as sand may be used as the core material.

  Next, a general vacuum injection molding method will be described with reference to the drawings. FIG. 1 shows a state before injecting resin, and FIG. 2 shows a state after resin impregnation.

  In each figure, 1 is a mold, 2 is an impregnated material placed on the mold, 3 is a resin fluidized bed, 4 is a release material, 5 is a bag film placed so as to cover them, 6 is A vacuum holding sealing material interposed between the bag film 5 and the mold 1, 7 and 8 are connectors attached to both ends of the bag film 5, and 9 is a resin reservoir tank connected to the connector 7 via a valve 10. , 11 is a resin for impregnation, 12 is a drain connected to the connector 8 via a valve 13, and 14 is a evacuation system line connected to this drain via a valve 15.

As shown in FIG. 1, an impregnated material 2 is placed on a molding die 1, and a resin fluidized bed 3 is disposed adjacently via a mold release material 4 thereon.
In this state, the bag film 5 is covered from above, and a sealing material 6 is disposed between the lower edge portion and the mold 1 and vacuum sealed.

When the connectors 7 and 8 are set on the bag film 5 and the valves 13 and 15 are opened, the air in the bag film 5 is discharged to the evacuation system line 14 through the drain 12, and the bag film 5 is maintained in a vacuum state. Is done.
When the valve 10 is opened in this state, as shown in FIG. 2, the resin 11 for impregnation in the resin storage tank 9 is supplied into the bag film 5 through the connector 7 and can flow into the resin fluidized bed 3. It is filled and supplied to the material 2 to be impregnated through the release material 4 and impregnated. At this time, since the resin for impregnation is held in the resin fluidized bed 3 in a flowable state, the resin is supplied from the resin fluidized bed 3 to the unimpregnated portion of the article 2 to be impregnated, and conversely from the excessively impregnated portion. The resin is sucked into the resin fluidized bed 3 and the resin content of the impregnated material 2 is made uniform.
The excess resin in the bag film 5 flows into the drain 12 through the connector 8, and the bubbles mixed in the resin are sucked out at this time, so that the object 2 to be impregnated is uniformly impregnated with the impregnating resin 11 as a whole. Does not remain.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.

Example 1
A reinforced plastic sandwich material was prepared by vacuum injection molding using the impregnated material and the core material shown in FIGS.
That is, as the forming die 1, a steel plate die having a size of 800 mm width × 1300 mm length was used. The material to be impregnated placed on the mold is composed of a liquid-permeable reinforcing material 202, a core material 17, and a liquid-permeable reinforcing material 201. The liquid-permeable reinforcing material 202 is formed by alternately laminating glass cloth with a basis weight of 800 (g / m ² ) and chopped strand mats with a basis weight of 900 (g / m ² ), 3 layers, a width of 500 mm, and a length of 1000 mm. The core material 17 placed thereon was a polypropylene foam having a foaming ratio of 20 times, and a width of 490 mm, a length of 990 mm, and a thickness of 50 mm was used. In the core member 17, through-holes 16 having a diameter of 1 mm are formed on the entire surface at a pitch of about 50 mm. The liquid-permeable reinforcing material 201 placed on the core material has the same configuration as 202. Around the core member 17, a strip-shaped impregnated article 203 having a width of 50 mm (the same thickness as the core member 17) laminated in five layers of chopped strand mat 800 (g / m ² ) is wound around the entire circumference.
In this way, the article to be impregnated as a whole is configured.
A release material (not shown) was placed on the impregnated material until it hits the mold, and the impregnated material was completely covered with the release material. As a release material, BLEDER LEASE B (trade name, manufactured by AIRTECH, 0.011 mm thick silicon-coated polyamide cloth) was used.
Further, the resin fluidized bed 3 was placed on the material to be impregnated through a release material to cover the material to be impregnated. As the resin fluidized bed 3, GREENFLOW 75 (trade name, manufactured by AIRTECH, 0.89 mm thick polypropylene net) was used.
Further, a bag film (not shown) was placed so as to cover the mold. As the bag film, KM1300 (trade name, manufactured by AIRTECH, polyamide film having a thickness of 0.25 mm) was used.
The mold 1 and the bag film were bonded with a sealing material (not shown) provided around the mold.
A vacuum valve for resin injection (not shown) and a vacuum valve for vacuuming (not shown) were arranged as shown in FIG.
In such a molding apparatus, the inside of the bag film was sucked at a vacuum pressure of 0.06 MPa.
As the impregnating resin (liquid thermosetting resin) 11, a vinyl ester resin [Neopol 8250 (trade name) manufactured by Nippon Iupika Co., Ltd.] (viscosity at a temperature of 20 ° C .: about 0) in which a curing agent and an accelerator are blended. .2 Pa · s)] was used.
When the vacuum valve was opened, the impregnating resin 11 flowed as shown in FIG. 3, and the whole was impregnated.
After the resin was cured, the resin was taken out from the molding die and visually checked for the presence or absence of an unimpregnated portion of the resin.
The sandwich material thus obtained had a good appearance with no resin-impregnated part on the upper side as well as the lower side in contact with the mold.

Example 2
As the core material 17, a polypropylene foam having a foaming ratio of 20 times, a width of 160 mm, a length of 490 mm, and a thickness of 50 mm was placed in the same manner as in Example 1 except that a gap 19 of about 5 mm was opened and placed side by side as shown in FIG. A reinforced plastic sandwich was prepared. The obtained sandwich material had good appearance with no resin-impregnated part observed on the lower side which was in contact with the mold as well as the upper side.

Example 3
A reinforced plastic sandwich was prepared in the same manner as in Example 1 except that the core material 17 had the same dimensions as in Example 1 and sand having an average particle diameter of 2 mm filled in a 20-mesh polyethylene net. . The obtained sandwich material had good appearance with no resin-impregnated part observed on the lower side which was in contact with the mold as well as the upper side.

Example 4
A reinforced plastic sandwich material was prepared in the same manner as in Example 1 except that the core material 17 had the same dimensions as in Example 1 and sand having an average particle diameter of 2 mm was filled in the core of a paper honeycomb sheet. did. The obtained sandwich material had good appearance with no resin-impregnated part observed on the lower side which was in contact with the mold as well as the upper side.

Comparative Example 1
As shown in FIGS. 6 and 7, a reinforced plastic is used in the same manner as in Example 1 except that a non-porous polypropylene foam having the same dimensions as in Example 1 and having no through holes is used as the core material 18. A sandwich material was prepared. In the obtained sandwich material, the resin non-impregnated portion 20 was observed on the lower side in contact with the mold, and the appearance was poor.

The schematic diagram before resin injection | pouring in an example of a vacuum injection molding method. The schematic diagram after resin injection | pouring in an example of a vacuum injection molding method. The schematic diagram in the resin impregnation in the vacuum injection molding of Examples 1 and 2. FIG. Sectional drawing of an example of the principal part in FIG. 3 (CC arrow view). Sectional drawing of another example of the principal part in FIG. 3 (CC arrow view). The schematic diagram in the vacuum injection molding of the comparative example 1 (resin impregnation initial stage). Schematic diagram in vacuum injection molding of Comparative Example 1 (at the end of resin impregnation)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Impregnated material 3 Resin fluidized bed 4 Release material 5 Bag film 6 Seal material 7,8 Connector 9 Resin storage tank 10,13,15 Valve 11 Impregnation resin 12 Drain 14 Vacuum drawing system line 16 Through hole 17 core Material 18 Foam without core (core material)
19 Clearance 20 Resin unimpregnated part

Claims (9)

  It is characterized by impregnating a liquid thermosetting resin by a vacuum injection molding method on an impregnated material in which a liquid-permeable reinforcing material is disposed on both surfaces of a liquid-permeable core portion, and then curing. A method of manufacturing a reinforced plastic sandwich.   The manufacturing method according to claim 1, wherein the liquid-permeable core portion is made of a resin foam.   3. The production method according to claim 2, wherein the resin foam is in the form of a sheet, and a large number of through-holes are spread and dispersed on the entire surface in the thickness direction.   2. The liquid-permeable core portion is formed by juxtaposing a plurality of resin foams between liquid-permeable reinforcing materials with gaps being substantially parallel to each other. Production method.   The manufacturing method according to claim 2, wherein the resin foam is an independent foam.   The manufacturing method according to claim 1, wherein the liquid-permeable core portion is formed of a liquid-permeable sheet-like body filled with a granular material.   The manufacturing method according to claim 6, wherein the sheet-like body is a honeycomb sheet.   The production method according to claim 1, wherein the liquid-permeable reinforcing material is a fiber base material.   9. The production method according to claim 8, wherein the fiber base material is at least one selected from the group consisting of a nonwoven fabric, a short fiber laminated mat, a sheet made of long fibers, a fabric, a woven fabric, and a knitted fabric. .

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