JP6933994B2 - Resin composite - Google Patents

Description

The present invention relates to a resin composite, and more particularly to a resin composite including a core material made of a resin foam and a fiber reinforced resin layer covering the core material.

Conventionally, a fiber reinforced resin material called FRP or the like has been widely used because it has both excellent lightness and strength.
As this type of fiber-reinforced resin material, a type in which short fibers are dispersed in a resin and a type in which a fiber base material such as a woven fabric is impregnated with a resin are known.

In recent years, a resin composite in which a fiber-reinforced resin material is laminated on a resin foam as a core material to form a fiber-reinforced resin layer on the core material has expanded its use.
This type of resin composite is formed of a fiber-reinforced resin layer having a hard surface and excellent smoothness, and a resin foam having excellent lightness is provided inside the fiber-reinforced resin layer to provide strength and lightness. It is widely used in applications where both are required.
Regarding such a resin composite, for example, in Patent Document 1 below (see Examples and the like), a resin is obtained by stacking a plurality of UD prepregs based on a fiber sheet in which carbon fibers are aligned in one direction. It is described that a fiber reinforced resin layer is formed on the foam.

Japanese Unexamined Patent Publication No. 2006-35671

When the resin foam and the fiber-reinforced resin material are adhered to each other, the resin composite as described above may entrain air to form voids on the surface of the fiber-reinforced resin layer, thereby exhibiting a sufficiently good aesthetic appearance. It has the problem that it can be difficult.

Therefore, the present invention has an object of solving such a problem, and an object of providing a resin composite having an excellent aesthetic appearance.

The present invention solves the above problems.
A core material made of resin foam and
A fiber reinforced resin layer covering the core material is provided.
The fiber reinforced resin layer is composed of a fiber base material and a sheet-shaped fiber reinforced resin material having a resin impregnated in the fiber base material.
A resin composite that satisfies the following formula (1) when the value of 5% compressive stress is P (MPa) and the average density of the whole including the core material and the fiber reinforced resin layer is D (g / cm ^3). Provide the body.

1 ≤ (P / D) ≤ 5 ... (1)

According to the present invention, it is possible to provide a resin composite having few voids and a beautiful appearance.

It is the schematic perspective view which showed the resin composite of one Embodiment. Cross-sectional view of the resin composite (cross-sectional view taken along the line II-II of FIG. 1). An enlarged cross-sectional view of a main part of the resin composite (enlarged view of Part III in FIG. 2).

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

FIG. 1 is a view showing the panel 100, and as shown in the figure, the panel 100 according to the present embodiment is slightly outwardly spread from the bottom wall portion 101 and the outer peripheral edge of the bottom wall portion 101. It has a peripheral side wall portion 102 that rises up, and a flange portion 103 that extends outward from the upper end of the peripheral side wall portion 102.
As shown in FIG. 2, the panel 100 in the present embodiment is provided with a core material 1 made of a resin foam only in the bottom wall portion 101.

The core material 1 in the present embodiment has a plate shape, the entire outer surface is covered with the fiber reinforced resin material, and the fiber reinforced resin layer 2 is laminated on all the surfaces.
Specifically, in the core material 1, one or a plurality of sheet-shaped fiber reinforced resin materials 20 are laminated on one surface side, and one or a plurality of fibers are also laminated on the other surface side opposite to the one surface side. The reinforced resin material 20 is laminated.
In the present embodiment, a plurality of fiber reinforced resin materials 20 are laminated on one surface side and the other surface side of the core material 1, respectively.
That is, the fiber reinforced resin layer 2 of the present embodiment has a laminated structure.

The fiber-reinforced resin layer 2 in the present embodiment, which is composed of a plurality of fiber-reinforced resin materials 20, is arranged on the surface layer portion of the panel 100 to form the surface 100a of the panel 100, and the fiber-reinforced resin material 21 and the above. The fiber reinforced resin material 26, which is closest to the core material 1 and is arranged at the position farthest from the surface 100a, is of a different type.
That is, they are common in that they have a fiber base material and a resin impregnated in the fiber base material, but these are different in the type of the fiber base material.

The fiber base material of the fiber reinforced resin material 21 constituting the surface layer portion of the panel 100 of the present embodiment is a woven fabric 21a composed of multifilament yarns, and the multifilament yarns are composed of a plurality of glass fibers. The fiber-reinforced resin material 26 arranged closest to the core material 1 includes a fiber sheet (not shown) composed of carbon fibers aligned in one direction as the fiber base material.

As described above, the fiber-reinforced resin layer 2 of the panel 100 of the present embodiment has a laminated structure and has a layer made of the fiber-reinforced resin material 21 having the woven fabric 21a on the most surface layer side. Between the layer and the core material 1, another layer composed of a second fiber reinforced resin material 26 different from the fiber reinforced resin material is provided, and the second fiber reinforced resin is provided. The fiber base material of the material 26 is composed of carbon fibers.
More specifically, the fiber-reinforced resin layer 2 is a fiber-reinforced resin in which a fiber sheet (hereinafter, also referred to as “carbon UD”) composed of carbon fibers aligned in one direction is impregnated with a heat-curable resin. Fiber reinforced with four layers composed of materials 23, 24, 25 and 26, and woven fabrics 21a and 22a (hereinafter also referred to as "glass cloth") composed of glass fibers impregnated with a heat-curable resin. It is provided with two layers composed of resin materials 21 and 22.
That is, the fiber reinforced resin layer 2 of the present embodiment has a six-layer structure.
The second fiber-reinforced resin materials 23, 24, 25, and 26 provided with carbon UD are laminated in a state in which the directions in which the carbon fibers are aligned are offset by 45 degrees from each other to form four layers on the core material side. However, the first fiber-reinforced resin materials 21 and 22 provided with the glass cloth form two layers on the surface side of the panel 100.

As described above, in the present embodiment, the bottom wall portion 101 has the core material 1 made of the resin foam, while the peripheral side wall portion 102 and the flange portion 103 do not have the core material 1. ..
The peripheral side wall portion 102 and the flange portion 103 are composed of a fiber-reinforced resin material laminated on the core material 1 on the bottom wall portion 101 and a continuous fiber-reinforced resin material.
That is, in the present embodiment, the fiber reinforced resin material having a larger area than the region where the core material 1 and the fiber reinforced resin material are adhered is adhered to the core material 1 to the outside of the region. An extension portion formed by extending the fiber-reinforced resin material is provided, and the extension portion constitutes a peripheral side wall portion 102 and a flange portion 103.
Therefore, the peripheral side wall portion 102 and the flange portion 103 are composed of six fiber-reinforced resin materials laminated on one surface side of the core material 1 and six fiber-reinforced resin materials laminated on the other surface side of the core material 1. It has a 12-layer structure in which and is directly bonded to each other.
That is, the peripheral side wall portion 102 and the flange portion 103 have a structure in which the fiber reinforced resin material provided with the carbon UD is sandwiched between the fiber reinforced resin material provided with the glass cloth.

As described above, the fiber-reinforced resin layer 2 of the panel 100 of the present embodiment has a first region 2a that is adhered to the core material 1 to form the bottom wall portion 101, and a peripheral side wall outside the first region 2a. It has a second region 2b in which fiber-reinforced resin materials are adhered to each other so as to form a portion 102 and a flange portion 103.

Glass fiber is usually less rigid than carbon fiber.
Therefore, the panel 100 of the present embodiment in which the surface 100a is made of the fiber-reinforced resin material 21 provided with the glass cloth can have a beautiful appearance because the surface state is relatively easy to adjust.
On the other hand, carbon fiber is lighter and more rigid than glass fiber.
Therefore, in the panel 100 of the present embodiment in which the fiber reinforced resin material 26 provided with the carbon UD is arranged at the position closest to the core material 1, the core material 1 is formed by the fiber reinforced resin material 26 and the three layers following the fiber reinforced resin material 26. It is possible to suppress that the unevenness of the surface of the surface affects the appearance.
Moreover, four fiber-reinforced resin materials 23, 24, 25, and 26 having carbon UD are arranged between the fiber-reinforced resin material 21 provided with the glass cloth and the core material 1, so that the panel 100 of the present embodiment can be used. Can exhibit excellent lightness.

The panel 100 is manufactured by adhering a fiber-reinforced resin material (hereinafter, also referred to as “prepreg sheet”) in which the resin 21b is uncured and a resin foam to be the core material 1 as described in detail later. However, it is difficult to completely prevent air from being entrained between the prepreg sheets or between the prepreg sheets and the core material 1 in this bonding process.
In some cases, the prepreg sheet itself contains air between the fibers.
Then, such air may remain as bubbles (voids) in the fiber reinforced resin layer 2 after the bonding step.

If voids are present in the fiber-reinforced resin material 21 constituting the surface 100a of the panel 100, it may be difficult to exhibit a sufficient aesthetic appearance.
When the appearance of the panel 100 is observed by a method as shown below and the surface quality of the fiber reinforced resin layer 2 is evaluated in four stages according to the following criteria, the determination is preferably 3 or more. Is more preferable.
In the following, this determination result may be referred to as a "void number index" or the like, and for example, a case where the determination result is "determination 4" may be referred to as a "void number index 4" or the like.

(Appearance observation method)
-Sprinkle a techpolymer (Sekisui Plastics Co., Ltd., MBX-8, particle size: 8 μm), which is a spherical fine particle polymer, on the surface of the resin composite, and blend it with a waste cloth or the like so that the particles are pushed into the void portion.
-Remove the particles other than the particles remaining in the void part with a waste cloth or the like.
-Observe the surface of the resin composite at × 20 times with a microscope (KEYENCE, VHX-1000), determine the void portion by color extraction, and automatically measure the number of voids. (There are white particles in the void part, and since the parts other than the void part are black, it can be distinguished by the color difference)

(Judgment method)
Judgment 1: The number of voids in an area of 50 mm × 50 mm is 101 or more.
Judgment 2: The number of voids in the area of 50 mm × 50 mm is 51-100.
Judgment 3: The number of voids in the area of 50 mm × 50 mm is 6-50.
Judgment 4: The number of voids in the area of 50 mm × 50 mm is 0-5.

The resin foam in the present embodiment preferably has a compressive strength (5% compressive stress) of 0.5 MPa or more.
The compressive strength of the resin foam used for the core material 1 is more preferably 0.6 MPa or more, further preferably 1.0 MPa or more.
It is preferable that the compressive strength is exerted in the direction in which pressure is applied in the bonding step (usually, in the direction orthogonal to the surface).
If the resin foam is to exhibit an excessively high compressive strength, the foaming ratio may be lowered to sacrifice lightness.
In such a respect, the compressive strength excessively high for the resin foam is usually 4 MPa or less.

The compressive strength (5% compressive stress) of the resin foam can be measured, for example, by cutting out a test piece having a size of 50 mm in length × 50 mm in width × 12.6 mm in thickness from the resin foam.
Compressive strength can be measured by the method described in JIS K 7220: 2006 "Hard foamed plastic-How to determine compressive properties".
The compressive strength of the resin foam is 1.5 mm / min in the thickness direction of the test piece using Orientec "Tencilon UCT-10T" universal tester and soft brain "UTPS-458X" universal tester data processing. It is obtained by compressing at a rate and measuring the compressive strength at the time of 5% compression.
The number of test specimens is usually set to 5 and the average value is calculated.
For the measurement, the test piece was adjusted to the JIS K 7100: 1999 symbol "23/50" (temperature 23 ° C., relative humidity 50%) for 16 hours under a second-class standard atmosphere, and then the same standard atmosphere. Do it below.
The compressive strength is obtained by using the origin of displacement as a regression point.

-The compressive strength σm (MPa) can be calculated by the following formula.

σm = Fm / A0

Fm: Maximum force (N) reached within 5% of deformation rate
A0: Initial cross-sectional area of the test piece (mm ² )

The compressive strength of the resin foam before the fiber-reinforced resin material is adhered is usually exhibited in the core material 1 after the panel 100 is formed.
Therefore, the panel 100 also usually exhibits a compressive strength (5% compressive strength) equal to or higher than that of the resin foam.
In order to confirm the compressive strength of the resin composite such as the panel 100, a test piece may be cut out from the resin composite and the compressive strength may be measured by the same method as that of the resin foam.
At this time, the test body has a quadrangular prism shape having a length of 50 mm and a width of 50 mm and a height of which is the thickness of the resin composite, and the quadrangular prism penetrates the central portion of the resin composite. It is cut out.
Therefore, in the cut-out test piece, the upper and lower two surfaces are usually fiber-reinforced resin layers, and the four side surfaces are in a state in which no fiber-reinforced resin material is present other than the upper and lower fiber-reinforced resin layers.
The compressive strength of the resin composite can be measured by measuring the above-mentioned compressive strength using the test body produced in this manner.

The compressive strength of the resin foam or the resin composite is usually increased by lowering the foaming ratio (increasing the apparent density).
Further, the compressive strength of the resin foam or the resin composite is usually increased by improving the closed cell property (reducing the open cell ratio).
Further, the compressive strength of the resin foam or the resin composite is usually increased by using a hard resin such as polyethylene terephthalate resin as a raw material.
The compressive strength of the resin foam or the resin composite can also be adjusted by the average cell diameter (thickness of the cell film) or the like.

In the panel 100 of the present embodiment, the value of 5% compressive stress is set to "P (MPa)", and the total mass (M) and volume (V) including the core material 1 and the fiber reinforced resin layer 2 are included. When the average density (M / V) obtained by is "D (g / cm ³ )", the following formula (1) is satisfied.

1 ≤ (P / D) ≤ 5 ... (1)

The apparent density of the resin foam constituting the panel 100 is preferably 0.01 g / cm ³ or more and 0.4 g / cm ³ or less.
The apparent density of the resin foam used as the core material 1 ^{is more preferably 0.1 g / cm 3} or more, and further preferably 0.3 g / cm ³ or more.
It is preferable that such an apparent density of the resin foam is also provided in the resin foam after the panel 100 is formed.

The apparent density of the resin foam can be measured by the method described in JIS K7222: 2005 "Foam plastics and rubber-How to determine the apparent density".
That is, the apparent density can be obtained in principle as follows.
(Apparent density measurement method)
A test piece of 100 cm ³ or more can be cut so as not to change the original cell structure of the material, its mass is measured, and it can be calculated by the following formula.

Density (g / cm ³ ) = test piece mass (g) / test piece volume (cm ³ )

The test piece for measurement shall be cut out from a sample 72 hours or more after being molded and left in an atmospheric condition of a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% for 16 hours or more.

It is preferable that the apparent density of the resin foam as described above is provided even in the state where the core material 1 is formed after the panel 100 is formed.

The resin foam can also be used as the core material 1 after being subjected to secondary processing such as cutting or thermoforming.
For example, the core material 1 of the present embodiment has a plate-like shape as described above, but the resin foam used as the core material 1 is formed by using a molding die corresponding to the shape of the core material 1. It may be made by slicing a massive resin foam thicker than the core material 1.

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 fiber base of a thermosetting resin in an uncured state before being bonded to the resin foam. It is a prepreg sheet impregnated in the material.
Therefore, the 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 heating and pressurizing conditions.

The panel 100 of the present embodiment can be produced by heat molding such as hot press molding using both male and female molds and autoclave molding using only one of them.
In such heat molding, it is preferable to flow the resin impregnated in the fiber-reinforced resin material to a region outside the product, and to expel air to the outside of the product to suppress the formation of voids.
Therefore, in the bonding step of adhering the fiber base material and the sheet-shaped fiber reinforced resin material having the resin impregnated in the fiber base material and the resin foam under heating and pressurizing conditions, the fiber reinforced resin material is used. It is preferable that the adhesive film is sandwiched between the resin foam and the resin foam to carry out the adhesion, and the amount of resin that can be flowed in the bonding step by the thermal melt of the adhesive film is increased.

As described above, the resin composite of the present embodiment is
A core material made of resin foam and
A fiber reinforced resin layer covering the core material is provided.
The fiber reinforced resin layer is composed of a fiber base material and a sheet-shaped fiber reinforced resin material having a resin impregnated in the fiber base material.
When the value of 5% compressive stress is P (MPa) and the average density of the whole including the core material and the fiber reinforced resin layer is D (g / cm ³ ), the following formula (1) is satisfied. be.

1 ≤ (P / D) ≤ 5 ... (1)

Since the resin composite of the present embodiment has high compressive strength for its density, it is possible to suppress the formation of voids during production.
That is, in the present embodiment, it is possible to obtain a resin composite having a good appearance with a high score of the void number index.
The resin composite is required to be lightweight, and the average density D (g / cm ³ ) of the resin composite is preferably 0.7 g / cm ³ or less.

In the resin composite in the present embodiment, the resin foam may be a bead foam molded product.
As a result, the above effects can be more prominently exhibited.

In addition to the above, various improvements may be added to the resin composite of the present embodiment and the method for producing the same.
That is, the present invention is not limited to the above examples.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

(Example 1)
A rectangular plate-shaped resin foam (bead foam molded product) formed of polyethylene terephthalate resin (PET) was prepared.
Separately from this, a plurality of prepreg sheets in which resin was impregnated and supported on carbon UD were prepared.
The prepared prepreg sheet had a sufficient area to cover the entire one side of the resin foam.
A plurality of prepreg sheets were laminated to form two laminated sheets.
These two laminated sheets were temporarily adhered to both sides of the resin foam to prepare a preformed body having a sandwich structure.
The bonding step of adhering the laminated sheet constituting the preformed body and the resin foam under heating and pressurizing conditions was carried out by a press manufacturing method, and 1.2 mm each on both sides of a plate-shaped core material having a thickness of 10 mm. A resin composite having a fiber-reinforced resin layer having a thickness was prepared.
For the obtained resin composite, the surface condition of the fiber-reinforced resin layer was observed and the void number index was investigated.
In addition, the average density (D: g / cm ³ ) of the obtained resin composite was measured, and a test piece was cut out from the central portion of the resin composite to measure 5% compressive strength (P: MPa).
As a result, it was found that the resin composite obtained here had a void number index of "4", an average density of "0.6 g / cm ³ ", and a 5% compressive strength of "0.6 MPa". ..
In addition, the apparent density of the resin foam used as the core material was measured.
As a result, it was found that the apparent density of the resin foam constituting the core material in the resin composite was 0.23 g / cm ^3.
The lightness was determined from the average density of the resin composite.
The judgment was "○" when the density was 0.7 g / cm ³ or less, and "x" when the average density was higher than ^{0.7 g / cm 3.}
As described above, since the average density of the resin composite obtained here was 0.6 g / cm ³ , the lightness of this resin composite was judged as “◯”.

(Example 2)
A resin composite was produced in the same manner as in Example 1 except that the resin foam was changed to an acrylic resin foam instead of the bead foam molded product made of polyethylene terephthalate resin, and evaluated in the same manner as in Example 1.

(Example 3)
A resin composite was produced in the same manner as before, except that the resin foam was changed to an acrylic resin foam cut out from a lumpy foam instead of a bead foam molded product, and evaluated in the same manner as before.

(Example 4, Comparative Example 1, Comparative Example 2)
Using resin foams having different apparent densities from Example 1, resin composites having different 5% compressive strength and average density from Example 1 were prepared.
The prepared resin composite was evaluated in the same manner as before.
The results are shown in the table below.

From the above, it can be seen that according to the present invention, a resin composite having an excellent aesthetic appearance can be provided.

1: Core material 2: Fiber reinforced resin layer 20 (21, 22, 23, 24, 25, 26): Fiber reinforced resin material 21a, 22a: Woven fabric (glass cloth)
21b: Resin 100: Panel (resin composite)
100a: Surface 101: Bottom wall 102: Peripheral wall 103: Brim X: Plane direction Y: Depth direction

Claims (6)

A core material made of resin foam and
A fiber reinforced resin layer that covers the entire outer surface of the core material is provided.
The fiber-reinforced resin layer is composed of a fiber base material and a sheet-shaped fiber-reinforced resin material having a resin impregnated in the fiber base material , and a plurality of the fiber-reinforced resin materials are laminated in the fiber-reinforced resin layer. ,
5% compressive stress, which is the stress when a test piece cut out so that the upper and lower two surfaces of the resin foam form the fiber reinforced resin layer is compressed by 5% in a direction orthogonal to the surface of the fiber reinforced resin layer. A resin composite satisfying the following formula (1) when the value of is P (MPa) and the average density of the whole including the core material and the fiber reinforced resin layer is D (g / cm ^3).

1.0 ≤ (P / D) ≤ 3.1 ... (1)
The resin composite according to claim 1, wherein the fiber base material is either a fiber sheet in which fibers are aligned in one direction or a woven fabric. The resin composite according to claim 1 or 2, wherein the fibers constituting the fiber base material are either glass fibers or carbon fibers. The resin composite according to claim 3, wherein the fibers constituting the fiber base material are carbon fibers. The resin composite according to any one of claims 1 to 4, wherein the resin foam is made of polyethylene terephthalate resin. The resin composite according to any one of claims 1 to 5, wherein the resin foam is a bead foam molded product.

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