JP2020037263A - Resin composite - Google Patents

Abstract

To obtain a resin composite having excellent strength.SOLUTION: The present invention provides a resin composite wherein a resin exudes from a fiber-reinforced resin layer to permeate a core material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin composite, and more particularly, to a resin composite including a core material formed of a resin foam and a fiber-reinforced resin layer containing a resin and a fiber.

Conventionally, a resin composite comprising a core material composed of a resin foam and a fiber reinforced resin layer containing a resin and a fiber, and the core material being covered by the fiber reinforced resin layer is used for various applications. ing.
This type of resin composite is required to have high strength while being lightweight (see Patent Document 1 below).

JP-A-2013-193119

As described in Patent Document 1, it is demanded to increase the strength of the resin composite as described above.
However, conventional resin composites have room for improvement in strength.
That is, the above demands have not been sufficiently satisfied.
Then, this invention was made in order to solve such a problem, and makes it a subject to provide the resin composite excellent in intensity | strength.

The inventors of the present invention have conducted intensive studies on the above problems, and found that reinforcing the interface between the fiber reinforced resin layer and the core material was particularly effective in improving the strength of the resin composite, and completed the present invention. It led to.
That is, the present invention includes a core material composed of a resin foam, and a fiber reinforced resin layer composed of a fiber reinforced material containing resin and fibers, wherein the core material is covered by the fiber reinforced resin layer. A resin composite, wherein the resin oozes out of the fiber reinforced resin layer and permeates the core material, and the maximum depth of penetration of the resin is the core material and the fiber reinforced resin. A resin composite having a thickness of 500 μm or more from the interface with the layer is provided.

In the present invention, the resin exudes from the fiber reinforced resin layer and permeates the core material.
That is, the resin composite of the present invention is reinforced by the resin that has penetrated the surface layer of the core material adjacent to the fiber-reinforced resin layer.
The infiltrated resin functions to support the mechanical strength exerted by the fiber reinforced resin layer from the inside of the fiber reinforced resin layer, and provides an intermediate strength between the resin foam and the fiber reinforced resin layer. It functions to suppress the occurrence of stress concentration at the interface between the core material and the fiber reinforced resin layer.
Therefore, according to the present invention, a resin composite having excellent strength can be provided.

It is the schematic perspective view which showed the resin composite of one Embodiment. FIG. 2 is a sectional view of the resin composite (a sectional view taken along line II-II in FIG. 1). FIG. 3 is an enlarged sectional view of a main part of the resin composite (an enlarged view of a part III in FIG. 2). FIG. 2 is a cross-sectional photograph (scanning electron micrograph: upper diagram) of the interface portion of the resin composite of Example 1 and an explanatory diagram thereof (lower diagram).

Hereinafter, the resin composite according to the embodiment of the present invention will be described by taking as an example a case where the resin composite is used as a sandwich panel.
First, the resin composite according to the present embodiment will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the sandwich panel 100 according to the present embodiment has a fiber-reinforced resin layer 2 laminated on both sides of a plate-shaped core material 1 and two fiber-reinforced resin layers 2. It has a structure in which the core material 1 is sandwiched between them.
That is, the sandwich panel 100 includes a first fiber-reinforced resin layer 2a that forms one surface 100a, and a second fiber-reinforced resin layer 2b that forms the other surface 100b.
The core material 1 in the sandwich panel 100 of the present embodiment has one surface side covered with a first fiber reinforced resin layer 2a and the other surface side covered with a second fiber reinforced resin layer 2b.
In the present embodiment, the core material 1 is in direct contact with these fiber reinforced resin layers 2a and 2b.

The first fiber reinforced resin layer 2a and the second fiber reinforced resin layer 2b are made of a sheet-like fiber reinforced material 20.
The first fiber reinforced resin layer 2a and the second fiber reinforced resin layer 2b in the present embodiment are formed by laminating a plurality of fiber reinforced materials 20 on the surface of the core material 1, respectively.

The fiber reinforcement 20 includes a fiber and a resin.
Specifically, the fiber reinforced material 20 of the present embodiment includes a base cloth 21 woven using a yarn in which a plurality of continuous fibers are bundled, and a resin 22 impregnated and supported on the base cloth 21. Having.
The fiber-reinforced resin layer 2 laminated on the surface of the core material 1 in the sandwich panel 100 is bonded to the core material 1 by the resin 22 and is integrated with the core material 1. ing.

The core material 1 includes a permeation region 11 in which the resin 22 of the fiber reinforcement 20 permeates at a portion constituting an interface XS with the fiber reinforced resin layer 2.
That is, in the sandwich panel 100 of the present embodiment, the resin 22 oozes out of the fiber reinforced resin layer 2 and permeates the core material 1.
The core material 1 of the present embodiment includes a non-penetrable region 12 in which the resin 22 has not penetrated inside the penetrating region 11.
That is, the core material 1 includes the permeation region 11 at both ends in the thickness direction Z of the sandwich panel 100, and includes the non-permeation region 12 at an intermediate portion of the permeation region 11.
FIG. 3 shows that the permeation region 11 is formed along the width direction X of the sandwich panel 100. However, the permeation region 11 also extends in the length direction Y of the sandwich panel 100. are doing.

The permeation region 11 is preferably formed such that the depth D from the interface XS is as uniform as possible, and the area of the sandwich panel 100 as viewed in the thickness direction is preferably larger.
When the area of the interface XS where the core material 1 and the fiber reinforced resin layer 2 are in contact with each other is S ₀ (cm ² ), and the area of the permeation region 11 is S ₁ (cm ² ), these area ratios (S ₁ / S ₀ ) preferably satisfies the following relational expression (1).

80% ≦ (S ₁ / S ₀ ) × 100% (1)

The area ratio (S ₁ / S ₀ ) more preferably satisfies the following relational expression (2), and particularly preferably satisfies the following relational expression (3).

85% ≦ (S ₁ / S ₀ ) × 100% (2)
90% ≦ (S ₁ / S ₀ ) × 100% (3)

The maximum depth (the maximum depth in a direction orthogonal to the interface) of the permeation region 11 in which the resin has penetrated is 500 μm or more from the interface XS between the core material 1 and the fiber-reinforced resin layer 2. Is preferred.
When the area of the portion where the resin permeates 500 μm or more from the interface XS is defined as S ₂ (cm ² ), the ratio of the area to the interface (S ₂ / S ₀ ) is expressed by the following relational expression ( Preferably, 4) is satisfied.

5% ≦ (S ₂ / S ₀ ) × 100% (4)

The area ratio (S ₂ / S ₀ ) more preferably satisfies the following relational expression (5), and particularly preferably satisfies the following relational expression (6).

10% ≦ (S ₂ / S ₀ ) × 100% (5)
20% ≦ (S ₂ / S ₀ ) × 100% (6)

  The average depth of the portion where the resin has penetrated is preferably 200 μm or more, more preferably 350 μm or more, and particularly preferably 500 μm or more.

  The average depth of the portion where the resin has penetrated is a section of a fixed length (L) in a direction along the interface XS in a cross section that appears by cutting the sandwich panel 100 in a direction orthogonal to the interface XS. In (2), the cross-sectional area (Sa) of the portion where the resin has permeated is obtained, and the cross-sectional area (Sa) can be obtained by dividing the cross-sectional area (Sa) by the length (L).

  The permeation region 11 is preferably in the above-mentioned state in one of the first fiber-reinforced resin layer 2a and the second fiber-reinforced resin layer 2b, and the first fiber-reinforced resin layer 2a It is more preferable that both the first and second fiber-reinforced resin layers 2b are in the above-described state.

In the present embodiment, the core material 1 is not subjected to cutting or the like on the surface 1a constituting the interface XS, and does not have a cut surface formed by cutting a resin foam on the surface 1a. .
The surface 1a of the core 1 is formed of a foamed film of a resin foam.

The core material 1 in the present embodiment can be a foamed sheet (extruded foamed sheet) having a thickness of less than 5 mm formed by an extrusion foaming method or a molded product obtained by thermoforming the foamed sheet.
The resin foam constituting the core material 1 may be a board (extruded foam board) or a rod (extruded foam rod) having a thickness of 5 mm to 50 mm formed by an extrusion foaming method.
The resin foam constituting the core material 1 may be a molded product obtained by foaming foamable resin beads or a resin block having a foaming property in a molding die (in-mold molded product).
Examples of the in-mold molded article include a bead foam molded article in which foamed resin particles are heat-sealed and integrated.
The core material 1 of the present embodiment is preferably either an extruded foam sheet or a bead foam molded product.

The extruded foam sheet or bead foam molded product used as the core material 1 is preferably subjected to a treatment for facilitating the infiltration of the resin during the production thereof.
In the resin foam, for example, by reducing the thickness of the bubble film on the surface, the resin of the fiber reinforcement can be easily permeated from the surface when the fiber reinforcement is laminated.
In addition, the resin foam can be made to easily infiltrate the resin of the fiber reinforcement from the surface by using a resin having high compatibility with the resin of the fiber reinforcement as a raw material.

In the present embodiment, the resin foam to be the core material 1 is made to easily penetrate the resin by the above-described treatment. Alternatively, the surface of the resin foam may be rubbed with a polishing sheet such as sandpaper or a belt sander to further reduce the thickness of the foam film, or a small hole may be formed in the foam film.
By performing a rubbing treatment with such an abrasive sheet, not only the degree of penetration of the resin can be easily adjusted, but also the surface of the resin foam becomes moderately rough and the bubble film is raised. Thus, a resin composite in which the core material 1 and the fiber-reinforced resin layer 2 are firmly bonded is easily obtained.

In the present embodiment, the surface of the resin foam may be sliced with a blade to completely remove the bubble film on the surface of the resin foam, and the surface may be a cut surface of the bubbles.
By slicing the surface of the resin foam and greatly opening the air bubbles on the lamination surface of the fiber reinforced material in this way, when laminating the fiber reinforced material and the resin foam, pressure applied between them is reduced. By adjusting, the penetration depth of the resin can be adjusted.
That is, if these are laminated and integrated by a hot press or the like, if a cut surface of bubbles is provided on the lamination surface, pressing is performed at a pressure higher than the normal pressing pressure, or a temperature condition higher than normal is set. If the resin is pressed to lower the viscosity of the resin than usual, the maximum depth of penetration of the resin is 500 μm or more from the interface between the core material 1 and the fiber reinforced resin layer. Can be easily obtained.

It is advantageous that the resin of the fiber reinforced material is a thermosetting resin such as an unsaturated polyester resin or an epoxy resin in order to exhibit excellent strength to the fiber reinforced resin layer 2.
In particular, the fiber reinforcement preferably contains an epoxy resin as the resin.
The fiber reinforcing material preferably contains a bisphenol-type epoxy resin as the epoxy resin, and more preferably contains bisphenol A diglycidyl ether.
The fiber reinforcement may include a novolak type epoxy resin as the epoxy resin.
The fiber reinforcing material may contain a component serving as a reactive diluent for the epoxy resin.
Examples of the reactive diluent include epichlorohydrin, butyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,6-hexanediol diglycidyl ether, and the like.

  When the epoxy resin is contained in the fiber-reinforced resin layer 2, the resin foam used as the core material 1 is a resin composition containing a copolymer of styrene, (meth) acrylate, and maleic anhydride. Has the effect that the epoxy resin easily penetrates.

When the resin contained in the fiber reinforcing material and the resin contained in the resin foam exhibit a high affinity, the resin of the fiber reinforcing material easily penetrates into the core material, but excessively If the affinity is high, the resin that has penetrated into the resin foam from the fiber reinforced material side causes the foam film constituting the resin foam to be melted at the interface between the core material 1 and the fiber reinforced resin layer 2. Sometimes it becomes.
In that case, only a large lump is formed on the surface layer portion of the core material 1 (the interface portion between the core material and the fiber reinforced resin layer) by the resin oozing out from the fiber reinforced resin layer 2, and the structure of the interface portion is reduced. It tends to be relatively simple.
On the other hand, if the affinity between the resin contained in the fiber reinforced material and the resin contained in the resin foam is appropriate, the resin exuded from the fiber reinforced resin layer 2 may be a foam film of a core material. Can be suppressed, and the resin can easily flow into the individual bubbles opened at the interface XS, so that a resin pool can be formed inside the plurality of bubbles.
That is, in such a case, the lump of resin formed on the surface layer of the core material 1 is finer than in a case where the bubble film is melted.
In this case, the structure of the interface becomes more complicated, a high anchoring effect is exerted between the core material 1 and the fiber reinforced resin layer 2, and a high peel strength can be exhibited therebetween.

  In the resin composite of the present embodiment, the resin exuded from the fiber reinforced resin layer 2 is not only infiltrated into the core 1, but also at the interface between the core and the fiber reinforced resin layer. A lump composed of the resin is formed therein, the lump is formed so as to be continuous with the resin of the fiber reinforced resin layer 2, and the lump is open at the interface. It is preferably formed in.

In the resin composite of the present embodiment, it is preferable that the resin is contained in two or more air bubbles adjacent to each other at the interface, and a lump of resin is formed in each of the bubbles.
In this case, the bubble film is sandwiched between the bubbles in which the respective lumps are accommodated by the two lumps which are continuous with the resin of the fiber reinforced resin layer.
Therefore, in such a case, a better anchor effect can be exhibited between the core material 1 and the fiber reinforced resin layer 2.

In the case described above, a bubble film is usually inserted between two adjacent masses in a direction opposite to the direction of resin exudation (direction away from the interface).
It is preferable that the bubble film between two adjacent masses is arranged obliquely rather than arranged along a direction orthogonal to the interface between the core material and the fiber reinforced resin layer.
For example, it is preferable that the angle of the bubble film with respect to the interface be 15 degrees or more and 75 degrees or less in a cross section when the sandwich panel 100 is cut along a plane orthogonal to the interface.

The sandwich panel 100 of the present embodiment is produced, for example, by bonding a fiber reinforced resin material (hereinafter also referred to as a “prepreg sheet”) in which the epoxy resin is uncured and a resin foam serving as the core material 1. Is done.
The fiber contained in the prepreg sheet together with the epoxy resin or the like can be glass fiber or carbon fiber.
That is, the base cloth 21 of the present embodiment can be a glass cloth or a carbon cloth.
Although the fiber-reinforced resin material of the present embodiment contains fibers in the form of a cloth, the fibers may be contained in the form of short fibers or the like.
The fiber reinforced resin material of the present embodiment may contain fibers in a state of a fiber sheet (hereinafter, also referred to as “carbon UD”) made of carbon fibers aligned in one direction.

  In the present embodiment, a styrene- (meth) acrylate-maleic anhydride copolymer is exemplified as a resin constituting the core 1, but the core 1 is made of a polycarbonate resin foam, a polystyrene resin foam. Alternatively, a resin foam such as a polyolefin resin foam, a polyamide resin foam, a polyester resin foam, or a general acrylic resin foam may be used.

As the resin foam, for example, one having an apparent density of 50 kg / m ³ or more and 700 kg / m ³ or less can be adopted.

The apparent density of the resin foam can be measured by the method described in JIS K7222: 2005 “Foamed plastic and rubber—determination of apparent density”.
That is, the apparent density can be determined in principle as follows.
(Apparent density measurement method)
A test piece of 100 cm ³ or more can be cut without changing the original cell structure of the material, and its mass can be measured and calculated by the following equation.

Apparent density (g / cm ³ ) = specimen mass (g) / specimen volume (cm ³ )

In addition, the test piece for measurement shall be cut out from the sample which passed 72 hours or more after the shaping | molding was performed, and shall be left for 16 hours or more in the atmospheric conditions of 23 ± 2 degreeC of temperature, and 50 ± 5% of humidity.

As the resin foam, for example, a resin foam having an open cell ratio of 40% or less can be employed.
The open cell ratio is preferably 35% or less, more preferably 25% or less, and particularly preferably 15% or less.
The open cell ratio of the resin foam was prepared by cutting a plurality of sheet samples of 25 mm length × 25 mm width from the resin foam, and overlapping the cut samples so that there was no space to produce a test piece having a thickness of 50 mm. You can ask.
Specifically, using a “Digimatic caliper” manufactured by Mitutoyo Corporation, the outer dimensions of the test piece were measured to 1/100 mm to determine the apparent volume (cm ³ ) of the test piece. Using a total of 1000 type (manufactured by Tokyo Science Co., Ltd.), the volume (cm ³ ) of the test piece was determined by the 1-1 / 2-1 atmospheric pressure method of ASTM D2856-87, and the open cell ratio (%) was calculated by the following equation. Can be obtained by
The open cell rate is determined, for example, as an average value of five test pieces.

Open cell ratio (%) = 100 × (apparent volume−air comparison specific gravity meter measurement volume) / apparent volume

In addition, the above-mentioned measurement shall be performed under the JIS K7100: 1999 symbol 23/50, class 2 environment after storing the test piece in a JIS K7100: 1999 symbol 23/50, class 2 environment for 16 hours. And
In addition, the air-comparison hydrometer shall be corrected using a standard sphere (large, 28.96 cc, small, 8.58 cc).

In the present embodiment, the fiber reinforced resin material for forming the fiber reinforced resin layer 2 on the surface of the core material 1 is a thermosetting resin in an uncured state before being bonded to a resin foam. It is a prepreg sheet impregnated in a material.
Therefore, the sandwich panel 100 of the present embodiment is manufactured by a method including an adhesion step of adhering the fiber reinforced resin material (prepreg sheet) and the resin foam under heat and pressure.

The sandwich panel 100 of the present embodiment can be manufactured by heat molding such as hot press molding using both male and female molds or autoclave molding using only one of them.
In the heat molding in the present embodiment, the resin impregnated in the fiber reinforced resin material is made to exude from the fiber reinforced resin layer 2 by heat and pressure applied to the fiber reinforced resin material, and the core material 1 Implemented to infiltrate.
Further, in the present embodiment, since the resin impregnated in the fiber reinforced resin material has thermosetting properties, when the fiber reinforced resin layer 2 is formed by heat molding, the resin 22 carried on the base cloth 21 is cured. As a result, the fiber reinforced resin layer 2 having excellent strength is formed.
Further, in the heat molding, the same resin as the fiber-reinforced resin material permeates the core material 1 to form the permeation region 11, and the resin permeated into the core material 1 is also thermoset.

The permeated region 11 into which the resin has penetrated has better mechanical strength such as flexural modulus than the non-permeated region 12.
The region in contact with the fiber reinforced resin layer 2 from the back side is the permeation region 11 having excellent strength in this way, so that the sandwich panel 100 exhibits excellent strength.
Further, if the permeation region 11 does not exist, the strength of the sandwich panel rapidly changes at the interface between the fiber reinforced resin layer and the core material, and when an external force is applied to the sandwich panel, the stress concentrates on the interface. Tends to occur.
On the other hand, in the sandwich panel 100 of the present embodiment, the presence of the permeation region 11 can suppress the stress concentration.
In order to exert such an effect more remarkably, the area of the permeation region 11 in a cross section obtained by slicing the core material in a plane parallel to the interface may gradually decrease from the interface toward the inside of the core material. preferable.

  In the present embodiment, a thermosetting resin is exemplified as a resin that is exuded from the fiber reinforced resin layer and penetrates into the core material because it is advantageous in exhibiting a high reinforcing effect in the permeation region 11. However, the resin may be a thermoplastic resin such as a polyolefin resin, a polyester resin, an acrylic resin, and a styrene resin.

Various modifications other than those described above can be made to the resin composite of the present embodiment and the method for producing the same.
Further, in the present embodiment, the case where the resin composite is a sandwich panel is taken as an example, but the form of the resin composite in the present invention is not limited to the sandwich panel.
That is, the present invention is not limited to the above examples.

  Next, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

(Preliminary experiment)
In the examples, since a resin composite is produced by pressing as described later, as a preliminary experiment, a study was conducted on conditions under which the depth of penetration of the resin into the resin foam was 500 μm or more.
First, a sample having a size of 150 mm × 150 mm was cut out from a sheet-shaped foam mainly composed of polyethylene terephthalate (a foamed sheet having a density of about 0.3 g / cm ³ ).
The surface of this sample was sliced thinly to prepare a core material having a thickness of about 3 mm in which cut surfaces of bubbles were exposed on both sides.
Similarly, 20 pieces of carbon FRP prepreg and 2 pieces of glass FRP prepreg cut into 150 mm × 150 mm were prepared.
In addition, each prepreg contained an epoxy resin as a resin.
The carbon FRP prepreg was “carbon UD”, and the base material was composed of carbon fibers aligned in one direction.
The substrate of the glass FRP prepreg was a glass cloth.
After laminating ten carbon FRP prepregs so that the outer peripheral edge was aligned with the upper surface side of the core material, one glass FRP prepreg was laminated on the surface of the outermost carbon FRP prepreg.
Similarly, after laminating ten carbon FRP prepregs on the lower surface side of the core material, one glass FRP prepreg was laminated on the surface of the outermost carbon FRP prepreg to prepare a preform.
The preform was hot-pressed at 125 ° C. to produce a resin composite in which the thickness of the core material was reduced by about 5% as compared with that before pressing.
This resin composite was cut along a plane orthogonal to the surface (cut in the thickness direction), and the cross section of the fiber reinforced resin layer was observed with a microscope (KEYENCE, VHX-1000) at a magnification of 50 times.
Observe the interface between the fiber reinforced resin layer and the core material, identify the point where the resin leached from the fiber reinforced resin layer has penetrated the core material most deeply, and determine the length from the interface to the tip of the resin that has permeated. It was measured and calculated as the maximum resin depth.
As a result, in this resin composite, the maximum resin depth was about 60 μm.

Next, a board-shaped bead foam molded product having a lower density (about half the density) than the sheet foam is prepared, and a sample having a size of 150 mm × 150 mm is cut out from the bead foam molded product. The surface was sliced thinly to prepare a core material having a thickness of about 7 mm in which cut surfaces of bubbles were exposed on both sides.
Using this core material, a preform was produced in the same manner as described above.
The preform was hot-pressed at 125 ° C. to produce a resin composite in which the thickness of the core material was reduced by about 6% as compared with that before pressing.
In this resin composite, the maximum resin depth was about 400 μm.
Based on the results, resin composites of Examples and Comparative Examples were prepared as follows.

(Example 1)
(Molding of resin composite)
A sample having a thickness of about 3 mm and a size of 150 mm × 150 mm was cut out from a sheet-like foam (foam sheet) containing polyethylene terephthalate as a main component and used as a core material.
The foamed sheet used as the core material was prepared by subjecting the surface to a rubbing treatment with sandpaper so that a hole was formed in the foam film on the surface.
Similarly, 20 pieces of carbon FRP prepreg (hereinafter, referred to as “CFRP1”) and two pieces of glass FRP prepreg (hereinafter, referred to as “GFRP1”) cut to 150 mm × 150 mm are prepared, and the outer peripheral edges are aligned on the upper surface side of the core material. Then, after ten CRFP1s were overlaid, one GFRP1 was overlaid on the surface of the outermost CRFP1.
The above CFRP1 is a carbon UD composed of carbon fibers aligned in one direction, and when overlapping with the core material, the directions of the vertically adjacent CRFP fibers are orthogonal.
Similarly, after ten CRFP1s were stacked on the lower surface side of the core material, one GFRP1 was stacked on the outermost CRFP1 surface to prepare a preform.
In addition, each prepreg contained an epoxy resin as a resin.
The configurations of CRFP1 and GFRP1 are as shown in Table 1 below.
The preformed body was pressed in a male and female mold under a heated state to produce a resin composite having a fiber reinforced resin layer composed of 10 CFRP1s and 1 GFRP1 formed on the upper and lower surfaces of a core material. .
Specifically, in the male and female molds, the pre-formed body is pressed and heated at a temperature of 120 to 130 ° C. for 10 minutes to completely cure the epoxy resin in CFRP1 and the epoxy resin in GFRP1 (curing). Step) to produce a resin composite.
As a result of measuring the thickness of the resin composite, the residual ratio of the thickness of the core after the production of the resin composite was 62.1% compared to the thickness of the original core.
In addition, the thickness of the resin composite was determined to be the thickness of the resin composite by sandwiching both surfaces between smooth metal plates of 200 mm × 200 mm and measuring the gap between the metal plates.
The gap between the metal plates was measured with a precision of 1/100 mm at the center of the four sides of the resin composite using "Digimatic Caliper" manufactured by Mitutoyo Corporation, and the arithmetic average of the four-side gap was defined as the thickness of the composite.
Further, assuming that the thickness of the fiber-reinforced resin layer is 1.00 mm, the value obtained by subtracting from the thickness of the resin composite is defined as the thickness of the core after the production of the resin composite, and is divided by the original thickness of the core. Thickness residual ratio.

(Section observation)
The resin composite was cut along a plane perpendicular to the surface, and the cross section of the fiber reinforced resin layer was observed at a magnification of 50 times with a microscope (KEYENCE, VHX-1000).
Observe the interface between the fiber reinforced resin layer and the core material, identify the point where the resin leached from the fiber reinforced resin layer has penetrated the core material most deeply, and determine the length from the interface to the tip of the resin that has permeated. It was measured and calculated as the maximum resin depth.

(Absorbed energy)
Five flat rectangular test pieces measuring 25 mm long × 150 mm wide were cut out from the resin composite of Example 1.
The bending load of each test piece was measured in accordance with JIS K7221-1: 2006 "Hard foamed plastic-Bending test-Part 1: Determination of flexure characteristics" except for the size of the test piece.
That is, the test piece was maintained in an environment of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% for 16 hours or more, and then measured in an environment of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5%. Using a Tensilon universal testing machine (trade name "UCT-10T" manufactured by Orientec Co., Ltd.) and a universal testing machine data processing software (trade name "UTPS-237S" manufactured by Soft Brain Co., Ltd.), a compression speed of 10 mm / min and a pressure wedge. The measurement was carried out under the condition that the distance between fulcrums was 100 mm as 5R and the support 5R. The number of test pieces was five.

With respect to the obtained results, the integrated value of the load-displacement graph from the start of the test to the displacement indicating the maximum point load was obtained, and the obtained five integrated values were arithmetically averaged to obtain the absorbed energy.
Table 2 below shows the measured values of the absorbed energy.

(Example 2)
A resin composite was produced in the same manner as in Example 1 except that a board-like foam (bead foam molded product) having a thickness of about 14 mm was used as a core material instead of a sheet-like foam having a thickness of about 3 mm. Then, the resin composite was evaluated in the same manner as in Example 1.

(Comparative Example 1)
A resin composite was prepared in the same manner as in Example 1, except that the material for forming the fiber-reinforced resin layer was changed, and that a foam film on the surface of the core material was left. Was evaluated.

(Comparative Example 2)
A resin composite was prepared in the same manner as in Example 2 except that the material for forming the fiber-reinforced resin layer was changed from CFRP1 to CFRP2, and that the foam film on the surface of the core material was left, and the same as in Example 2 The evaluation of the resin composite was carried out.

  The details of GFRP and CFRP used in each of the examples and comparative examples, and the results of the evaluation and the like are shown in Tables 1 and 2 below.

In Table 1, “FW” means the mass of the fiber per unit area, and “Rc” means the mass of the resin per unit area.
"TAW" in Table 1 means the total mass per unit area.

FIG. 4 shows the state of the interface between the fiber-reinforced resin layer and the core in the resin composite of Example 1 among the resin composites prepared as described above.
In FIG. 4, the upper figure is a photograph taken by a scanning electron microscope of a cross section of the resin composite (a cross section in a direction orthogonal to the interface between the core material 1 and the fiber reinforced resin layer 2), and the lower figure is an explanatory view thereof. is there.
In the figure below, hatched portions are hatched portions where the presence of resin is observed. In this embodiment, a plurality of aggregates RX made of resin are formed in the core material at the interface. Was.
Further, in this example, the resin flowed into the bubbles opened at the interface XS to form several lump bodies RX, and the bubble film CF was present so as to be sandwiched between the two lump bodies.

  From the above, it is understood that a resin composite having excellent strength can be obtained according to the present invention.

1: core material, 2: fiber reinforced resin layer, 11: penetration area, 100: sandwich panel (resin composite)

Claims (3)

A resin composite comprising a core material made of a resin foam, and a fiber reinforced resin layer made of a fiber reinforced material containing a resin and a fiber, wherein the core material is covered with the fiber reinforced resin layer. hand,
The resin oozes out of the fiber reinforced resin layer and permeates the core material, and the maximum depth at which the resin permeates is 500 μm or more from the interface between the core material and the fiber reinforced resin layer. A resin composite.   The resin composite according to claim 1, wherein the average depth of penetration of the resin is 350 µm or more.   3. The resin composite according to claim 1, wherein the core material is provided with air bubbles that are open at the interface, and the resin exuded from the fiber-reinforced resin layer is contained in the air bubbles.