WO2021200862A1

WO2021200862A1 - Composite

Info

Publication number: WO2021200862A1
Application number: PCT/JP2021/013387
Authority: WO
Inventors: 圭一奥山; 千愛今市; 純南舘; 純一 ▲角▼田; 智亮中西
Original assignee: Ａｇｃ株式会社
Priority date: 2020-03-31
Filing date: 2021-03-29
Publication date: 2021-10-07
Also published as: JP2023072095A

Abstract

Provided is a composite having excellent heat resistance.　This composite is provided with multiple layers stacked on top of each other, and multiple long fibers disposed inside the layers in parallel to a direction orthogonal to the thickness direction of the layers. The long fibers disposed in the n-th layer and the long fibers disposed in the n+1 layer intersect with each other. Said n is a positive integer. The layers include a matrix resin containing a thermoplastic resin and have a porosity of 3-20%.

Description

Complex

The present invention relates to a complex.

Conventionally, a composite composed of fibers such as carbon fibers and a matrix resin has been used as, for example, a heat-resistant material (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-42996

In recent years, the market has requested the development of better heat-resistant materials.
Therefore, an object of the present invention is to provide a complex having excellent heat resistance.

As a result of diligent studies, the present inventors have found that the above object can be achieved by adopting the following configuration.
That is, the present invention provides the following [1] to [10].
[1] A plurality of laminated layers and a plurality of long fibers arranged in parallel in a direction orthogonal to the thickness direction of the layer are provided inside the layer, and are arranged in the nth layer. The long fibers are crossed with the long fibers arranged in the n + 1th layer, where n is a positive integer and the layer has a matrix resin containing a thermoplastic resin. A complex having a void ratio of 3 to 20%.
[2] The complex according to the above [1], wherein the long fibers are carbon fibers.

[3] The complex according to the above [1] or [2], wherein the matrix resin has a 5% mass reduction temperature under nitrogen at 150 ° C. or higher, and the thermal deformation temperature of the matrix resin is 100 ° C. or higher. ..
[4] The complex according to the above [3], wherein the thermal deformation temperature is 150 ° C. or higher.
[5] The complex according to any one of the above [1] to [4], wherein the thermoplastic resin contains an aromatic polyetherketone.
[6] The complex according to the above [5], wherein the aromatic polyetherketone is a polyetheretherketone.
[7] The complex according to any one of [1] to [6] above, wherein the long fibers have a diameter of 1 to 20 μm.
[8] The complex according to any one of the above [1] to [7], wherein the content of the long fibers is 20 to 80% by mass.

[9] The method for producing the composite according to any one of the above [1] to [8], which comprises a matrix resin containing a thermoplastic resin and a plurality of long fibers, and the plurality of lengths. Using a linear body in which fibers are arranged in the length direction of the linear body, the linear body is arranged in one direction and melt-pressed, and then adjacent to the linear body after the melt-pressing, another said A second layer adjacent to the layer is formed in the same manner except that the linear bodies are arranged in parallel, melt-pressed, and repeated to form one layer in the complex, and then the direction of the linear bodies is changed. A method for producing a complex, which comprises forming a layer of the above-mentioned layer and optionally repeating the layer formation.
[10] The production method according to [9], wherein the long fibers are continuous fibers.

According to the present invention, it is possible to provide a complex having excellent heat resistance.

It is a perspective view which shows the complex. It is a perspective view which shows the linear body. It is a perspective view which shows the layer. It is a graph which shows the result (temperature of a test piece) of an arc heating test.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3.
However, the present invention is not limited to the following embodiments. Various modifications and substitutions can be made to the following embodiments without departing from the scope of the present invention.

[Complex]
FIG. 1 is a perspective view showing the complex 1.
The complex 1 is a laminated body in which a plurality of layers 2 are laminated.
Inside each layer 2, a plurality of long fibers 3 are arranged in parallel in a direction orthogonal to the thickness direction of the layer 2. The portion of the layer 2 excluding the long fibers 3 is a matrix resin 4 containing a thermoplastic resin. The matrix resin 4 has a function of adhering a plurality of long fibers and at the same time adhering layers 2 to each other. The long fibers 3 are preferably continuous from one fiber cut surface of layer 2 to the other fiber cut surface.

The length fibers 3 arranged in the nth layer (for example, the first layer from the bottom in FIG. 1) and the lengths 2 arranged in the n + 1th layer (for example, the second layer from the bottom in FIG. 1). The fibers 3 intersect with each other in a top view when the stacking direction is on the upper side, and are non-parallel to each other. Here, n is a positive integer. More specifically, assuming that the number of layers of the complex 1 is m, n is an integer in the range of 1 to (m-1).
In FIG. 1, in order to clearly indicate the intersection of the long fibers 3, one long fiber 3 incorporated in each layer 2 is shown by a broken line.

A plurality of voids (not shown) are formed in each of the layers 2 (particularly, the matrix resin 4) constituting the complex 1.
The porosity of the complex 1 is 3 to 20%.

Such a complex 1 is excellent in heat resistance.
The reason is presumed as follows.
First, in the complex 1, long fibers 3 long in one direction are alternately incorporated in each layer 2. As a result, it is considered that the complex 1 has a tough structure that is less likely to collapse due to heat than, for example, a complex in which short fibers are randomly dispersed inside.
Further, it is considered that the complex 1 contains an appropriate amount of air by having an appropriate void, thereby having good heat insulating properties.
In addition, it is considered that when the complex 1 has appropriate voids, the gas due to the decomposition of the matrix resin 4 is easily volatilized, and an endothermic effect can be obtained. It is considered that this makes it possible to cool the complex 1 placed in a high temperature environment and improve the heat resistance of the complex 1.

The porosity of the complex 1 is preferably 6% or more, more preferably 8% or more, still more preferably 10% or more, because the heat resistance of the complex 1 is more excellent.
On the other hand, the porosity of the complex 1 is preferably 18% or less, more preferably 16% or less, further preferably 14% or less, because the heat resistance of the complex 1 is more excellent while maintaining the strength of the complex 1. preferable.

The porosity can be measured by the combustion method described in JIS K 7075.
The porosity can also be estimated by the X-ray CT (X-ray Computed Tomography) method by confirming the correlation by the combustion method.
The method for measuring the porosity using the X-ray CT method is as follows.
First, a scanned image of the complex 1 is acquired using an X-ray CT apparatus. As the X-ray CT apparatus, for example, SMX-225CT FPD manufactured by Shimadzu Corporation can be used. The conditions for acquiring the scan image of the composite 1 are, for example, a tube voltage of 75 kV, a tube current of 70 μA, a scan image size of 1024 pixels × 1024 pixels, a slice thickness of 0.104 mm, and a scan accuracy of 360 °. Can be mentioned.
Next, the void ratio is calculated from the acquired scanned image using analysis software. As the analysis software, for example, VS Studio MAX manufactured by Volume Graphics can be used. As the analysis algorithm, VG Easy Pole in the above analysis software is used. Select the relative mode as the analysis mode. The minimum voxel size is 8 voxels. With respect to the obtained analysis result, the shade level of the threshold value of the interface between the void and the matrix resin 4 and the long fiber 3 is adjusted so that the void can be clearly identified. Specifically, parameters such as gray value contrast and the level of internal cleaning of voids are adjusted. This parameter is adjusted with reference to the porosity measured by the above combustion method.

Hereinafter, the complex 1 will be described in more detail.

When the complex 1 is viewed from the upper surface side or the lower surface side, the angle in the longitudinal direction of the long fibers 3 of the n + 1th layer (hereinafter, also referred to as “intersection angle”) with respect to the longitudinal direction of the long fibers 3 of the nth layer is 0. If it exceeds °, it is not particularly limited, and is preferably 45 ° or more. FIG. 1 shows an example in which the crossing angle is 90 °.

The size (thickness, etc.) of the complex 1 is not particularly limited, and is appropriately set according to the intended use and the like.
The complex 1 has three layers in FIG. 1, but is not particularly limited as long as it has two or more layers. The number of layers of the complex 1 is appropriately set according to the thickness of the complex 1 and the like.
Complex 1 is a rectangular parallelepiped in FIG. 1, but is not limited thereto. For example, each layer 2 may have a different size (length in a direction orthogonal to the thickness direction) and may be provided with a step.

The thickness of the layer 2 may be the same or different for each layer 2, but the heat resistance of the complex 1 is more excellent, and the homogeneity of the obtained complex 1 is improved, so that the mechanical properties are designed. The same is preferred because it is easy.
The thickness of the layer 2 is appropriately set according to the thickness of the complex 1 and the like, but is, for example, 0.1 mm or more, preferably 0.2 mm or more. On the other hand, 0.5 mm or less is preferable, and 0.4 mm or less is more preferable.
The thickness of the layer 2 is a value obtained by measuring using a scanning electron microscope (SEM), an optical microscope, or a laser microscope, and is an average value of any five points.

Examples of the long fibers 3 contained in the composite 1 include carbon fibers, glass fibers, silica fibers (quartz fibers), silicon carbide (SiC) fibers, alumina fibers, zirconia fibers, boron fibers and other inorganic fibers, and aramid fibers. , Nylon fiber, polyester fiber, organic fiber such as PBO (polyparaphenylene benzobisoxazole) fiber and the like. Complex 1 may contain two or more of these.
Of these, inorganic fibers are preferable, and carbon fibers are more preferable, because the heat resistance of the complex 1 is more excellent.

The long fiber 3 is, for example, a material having a cylindrical shape that is long in one direction.
The length (distance in the longitudinal direction) of the long fibers 3 is preferably 10 cm or more, and more preferably the distance from one side surface to the other side surface, which is the fiber cutting surface of the layer 2. ..
The diameter of the long fibers 3 is preferably 1 μm or more, more preferably 3 μm or more, because the complex 1 has high strength. On the other hand, the diameter of the long fiber 3 is preferably 20 μm or less, more preferably 15 μm or less, because it is easy to manufacture the linear body 5 (see FIG. 2) described later.
The diameter of the long fiber 3 is a value obtained by measuring using a scanning electron microscope (SEM), an optical microscope, or a laser microscope, and is an average value of any five points.

The content of the long fibers 3 in the complex 1 is preferably 20% by mass or more, more preferably 40% by mass or more, because the heat resistance of the complex 1 is more excellent while maintaining the strength of the complex 1.
On the other hand, the content of the long fibers 3 in the complex 1 is 80% by mass or less for the reason that the complex 1 can be easily molded and the amount of the matrix resin 4 for adhering the layers 2 to each other is sufficiently secured. It is preferably 60% by mass or less, more preferably 60% by mass or less.
The content of long fibers 3 is measured by thermogravimetric analysis (TGA).

Examples of the thermoplastic resin contained in the matrix resin 4 in the composite 1 include polyethylene, polypropylene, polyamide (PA), polysulfone (PSU), polyethersulfone (PES), polystyrene (PS), polyphthalamide (PPA), and the like. Examples thereof include polyphenylsulfone (PPSU), liquid crystal polymer (LCP), polyetherimide (PEI), polyphenylsulfide (PPS), aromatic polyetherketone (PAEK) and the like.
Of these, PAEK is preferable because it has a high melting point, decomposition temperature, and mechanical strength, and the heat resistance of the complex 1 is more excellent.

Examples of PAEK include polyetherketone (PEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), and polyetheretherketoneketone (PEEKK).
Of these, PEEK is preferable because it has a higher melting point, decomposition temperature, and mechanical strength, further excellent heat resistance of the complex 1, and excellent chemical resistance.

The matrix resin 4 may contain other resins, and examples thereof include thermosetting resins such as unsaturated polyester, epoxy, and polyimide (PI).

The melt flow rate (MFR) of the matrix resin 4 is preferably 2,000 g / 10 minutes or less because the impact resistance of the complex 1 is excellent.
On the other hand, the MFR of the matrix resin 4 is preferably 1 g / 10 minutes or more because the matrix resin 4 is easily deformed when the complex 1 is produced as described later.
Melt flow rate (MFR) can be measured according to ASTM D1238.

The 5% mass reduction temperature of the matrix resin 4 under nitrogen is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, still more preferably 500 ° C. or higher. In this case, the complex 1 exposed to a high temperature environment is less likely to be thermally decomposed. Further, the heat insulating effect can be obtained by covering the complex 1 with the gas generated by the thermal decomposition.
On the other hand, the 5% mass reduction temperature of the matrix resin 4 under nitrogen is preferably 1,000 ° C. or lower, more preferably 800 ° C. or lower, and even more preferably 600 ° C. or lower. In this case, when the composite 1 is manufactured as described later, the matrix resin 4 is easily melted and the adhesion to the long fibers 3 is excellent.
The mass loss temperature of 5% under nitrogen is measured at 10 ° C./min under nitrogen using thermogravimetric analysis (TGA), and the mass is 5% based on the mass at the start of measurement. The temperature at which weight is reduced.

The thermal deformation temperature of the matrix resin 4 is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 160 ° C. or higher. In this case, the complex 1 is not easily deformed and is of high quality.
On the other hand, the thermal deformation temperature of the matrix resin 4 is preferably 500 ° C. or lower, more preferably 450 ° C. or lower. In this case, when the complex 1 is manufactured as described later, the matrix resin 4 is easily melted, and the adhesion between the layers 2 is excellent.
The heat distortion temperature is the deflection temperature under load obtained in accordance with the method A (1.8 MPa) of ISO75 (JIS K 7191).

In order to improve the mechanical properties, thermal properties, electrical properties, workability, etc. of the complex 1, each layer 2 constituting the complex 1 further contains a filler (however, long fibers 3 and a matrix resin 4). Excludes) and additives may be included.
Examples of the filler include short carbon fibers, silica, talc, short glass fibers, inorganic fillers such as titanium oxide, short polyester fibers, and organic fillers such as short cellulose fibers. In addition, as additives, inorganic powders other than the above, organic powders other than the above, fluororesin powders, elastomer powders, fiber treatment agents and the like can also be used.

The thermal deformation temperature of the complex 1 is preferably 190 ° C. or higher, more preferably 200 ° C. or higher, further preferably 210 ° C. or higher, and particularly preferably 300 ° C. or higher. In this case, the complex 1 is not easily deformed in a high temperature environment and has excellent dimensional stability.
On the other hand, the thermal deformation temperature of the complex 1 is preferably 500 ° C. or lower, more preferably 450 ° C. or lower, and even more preferably 400 ° C. or lower. In this case, when the complex 1 is manufactured, the adhesion between the layers 2 is excellent.

[Use of complex]
The use of the complex 1 is not particularly limited. Specific examples of applications of the complex 1 include parts for mobility (parts used for automobiles, bicycles, ships, aircraft, electric vertical take-off and landing aircraft, spacecraft, etc.), building parts, parts for electronic devices, and the like. .. The complex 1 can be used for the frame, wings, skeleton, exterior material, interior material, and the like of these parts.

[Method for manufacturing complex]
Next, an example of a method for producing the complex 1 will be described with reference to FIGS. 2 and 3.
FIG. 2 is a perspective view showing the linear body 5. FIG. 3 is a perspective view showing the layer 2.
The linear body 5 is a cylindrical material composed of the above-mentioned long fibers 3 (for example, carbon fibers) and a matrix resin 4 containing a thermoplastic resin. The cross-sectional shape of the linear body 5 is a circle or an ellipse. A plurality of long fibers 3 are built in one linear body 5, and the long fibers 3 are arranged in the length direction of the linear body 5, and most of them are continuous from the tip to the end of the linear body 5. doing. The linear body 5 has continuous fibers and a matrix resin arranged in the length direction thereof, and is preferably a long linear body having the same length as the continuous fibers. By using such a long linear body, a composite in which long fibers are arranged in a predetermined direction can be produced by a filament winding method or another long fiber reinforced resin molding method.

As an example, when producing the complex 1 having the shape shown in FIG. 1, one linear body 5 (see FIG. 2) is first melted and then pressed. Another linear body 5 is arranged in parallel next to the pressed linear body 5, and similarly melted and pressed. By repeating this, one layer 2 (see FIG. 3) is formed.
Next, the direction of the linear body 5 is changed to form one layer 2 in the same manner.
By laminating a plurality of layers 2, the above-mentioned complex 1 (see FIG. 1) can be obtained.

The length and diameter of the linear body 5 to be used are appropriately selected according to the layer 2 and the complex 1 to be formed.
For example, the diameter of the linear body 5 is 1 to 2 mm, and the number of long fibers 3 incorporated in the linear body 5 is 5,000 to 50,000, but the diameter is not limited thereto.

Sectional density of the long fibers 3 in linear body 5, the reason that complex 1 obtained becomes high strength is preferably 7,000 / mm ² or more, 10,000 / mm ² or more is more preferable.
Meanwhile, cross-sectional density of the long fibers 3 in the linear member 5 is preferably 20,000 / mm ² or less, more preferably 18,000 / mm ² or less. In this case, the long fibers 3 become more compatible with the matrix resin 4, and the adhesion between the long fibers 3 and the matrix resin 4 is improved. As a result, the strength of the obtained complex 1 can be improved.

The content of the long fibers 3 in the linear body 5 can be regarded as the content of the long fibers 3 in the obtained complex 1.

The production of such a complex 1 is preferably carried out using a three-dimensional (3D) printer based on Fused Deposition Modeling (FDM) or Directed energy deposition (DED). .. This is because a relatively large complex 1 can be produced with high definition, and a linear body 5 using various thermoplastic resins can be used as the matrix resin 4.
When the linear body 5 in which the matrix resin 4 (thermoplastic resin) is PAEK (particularly PEEK) is used, it is more preferable to use the directed energy deposition method because the adhesion between the layers 2 can be improved. ..

Specifically, for example, first, a long linear body 5 wound on a spool or the like is discharged from the head of a 3D printer onto a build plate or the like to irradiate the laser beam. In the linear body 5 irradiated with the laser light, the matrix resin 4 containing the thermoplastic resin is melted by heat conduction from the long fibers 3 (for example, carbon fibers) that have absorbed the laser light.
Next, the linear body 5 in which the matrix resin 4 is melted is pressed by using a compression roller of a 3D printer. Then, the cooled linear body 5 is cut and separated from the head of the 3D printer.
By repeating such discharge of the linear body 5, irradiation of laser light, pressing by a compression roller, and cutting, the layer 2 is formed, and eventually the complex 1 is manufactured.

By adjusting the overlap rate of the linear body 5, the porosity of the finally obtained complex 1 can be adjusted.
The overlap rate of the linear body 5 is preferably 20% or less, more preferably 15% or less, further preferably 10% or less, particularly preferably 5% or less, and most preferably 0% or less. In this case, the outermost surface after forming each layer 2 can be smoothed while adjusting the porosity of the complex 1.
On the other hand, the overlap rate of the linear body 5 is preferably −10% or more, more preferably −5% or more, further preferably -3% or more. In this case, the porosity of the complex 1 can be reduced while maintaining the strength of the complex 1.
The overlapping rate of the linear bodies 5 is a value expressed as a percentage by dividing the width (overlapping width) at which adjacent linear bodies 5 overlap each other by the diameter of the linear bodies 5. A negative value means that a groove exists between the adjacent linear bodies 5, and the shortest distance of the groove is used instead of the overlapping width.

Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited to the following examples.

Hereinafter, Example 1 is an example, and Example 2 is a comparative example.

<Example 1>
The complex described with reference to FIG. 1 was made according to the method described with reference to FIGS. 2 and 3 and subjected to an arc heating test. Hereinafter, a detailed description will be given.

<< Preparation of complex >>
A complex was produced using a 3D printer having a 6-axis articulated arm and a head for discharging (printing) a linear body at the tip thereof.

The linear body used contains a plurality of continuous carbon fibers (having the same length as the linear body), and the details thereof are as follows.
-Diameter of striatum: 1.5 mm
・ Number of carbon fibers per linear body: 11,000 ・ Carbon fiber diameter: 8 μm
-Carbon fiber content: 56.5% by mass
-Matrix resin: PEEK (melting point: 343 ° C., MFR: 36 g / 10 minutes)
・ 5% mass reduction temperature of matrix resin under nitrogen: 556 ° C
・ Thermal deformation temperature of matrix resin: 160 ℃

Other physical characteristics of the used linear body are as follows.
-Tensile strength: 1,200 MPa
-Tension elastic modulus: 105 GPa
-Specific gravity: 1.5 x 10 ^-3 kg / m ³

The linear body was dried before use. Specifically, the linear body wound on the spool was placed in an oven (PVH-331M, manufactured by ESPEC) and dried at 100 ° C. for 8 hours in an air atmosphere.
After drying, the striatum was rewound into a metal spool using a linear winder (UniSpooler, manufactured by Showmark).
After that, a metal spool around which a linear body was wound was installed in a 3D printer.

Before operating the 3D printer, first, data of a complex having dimensions of 150 mm × 150 mm × 30 mm was created as a complex for an arc heating test.
In the created data, the longitudinal direction of the linear body discharged from the head was staggered for each layer (intersection angle was set to 90 °). That is, when the angle in the longitudinal direction of the linear body of the first layer was 0 °, the angle of the second layer was 90 ° and that of the third layer was 0 °, and this was repeated thereafter.
Data were created so that the overlap rate of the striatum was -5% in each layer.

Based on the created data, the 3D printer was operated and the production of the complex was started on the build plate. A polycarbonate sheet was previously attached to the surface of the build plate by vacuuming for heat diffusion.

Specifically, first, the linear body was sent out to the head with an appropriate tension by an accumulator provided in the 3D printer, and discharged from the head at a speed of 30 mm / sec.
During this period, the condition of the striatum was monitored using a camera in order to immediately detect the occurrence of defective delivery.

Next, the linear body discharged from the head was irradiated with a laser beam from a laser provided in the 3D printer. In the linear body irradiated with the laser light, the carbon fibers absorbed the laser light, and the heat conduction from the carbon fibers melted PEEK, which is a thermoplastic resin.
During the irradiation of the laser beam, the temperature of the striatum was monitored using an IR camera (Thermal viewer, manufactured by FLIR). The virtual temperature displayed on the monitor of the IR camera was monitored, and the output of the laser beam was controlled so that the temperature of the linear body was in the range of 400 ° C. or higher and 500 ° C. or lower.
During the irradiation of the laser beam, nitrogen was injected onto the linear body from the tube provided in the 3D printer to inhibit the combustion of the linear body due to the irradiation of the laser light.

Then, the linear body irradiated with the laser beam was pressed using the compression roller provided in the 3D printer. At this time, the compression roller was controlled so that the height of the linear body after pressing was 0.35 mm.

After irradiation with the laser beam and pressing by the compression roller, air was blown from the tube onto the striatum to cool the striatum.
After cooling, the linear body was cut by a cutter provided on the head and separated from the head.

By repeating such discharge of the linear body, irradiation of the laser beam, pressing by the compression roller, and cutting, a complex for an arc heating test was prepared.
The complex was peeled off from the build plate after preparation, and the surface was polished.
When the porosity and the thermal deformation temperature of the produced complex for the arc heating test were determined by the above-mentioned method, the porosity was 12% and the thermal deformation temperature was 350 ° C.
In addition, the complex for the arc heating test had about 43 layers.

《Arc heating test》
From the prepared composite for arc heating test (dimensions: 150 mm × 150 mm × 30 mm), a cylindrical test piece having a diameter of 20 mm and a height of 30 mm was hollowed out and subjected to an arc heating test.
The arc heating test is a test that simulates the state of re-entry into the atmosphere. In general, the arc discharge generated a high thermal content airflow, which heated the specimen.

More specifically, the arc heating test was carried out in the 750 kW arc heating wind tunnel of the Japan Aerospace Exploration Agency (Sagamihara Campus) as follows.
First, the test piece was placed inside a closed measurement room. One bottom surface of the cylindrical test piece was made to face the arc heater which is a heat source. The distance from the arc heater to the bottom surface of the test piece was set to 100 mm.
Next, an arc discharge controlled by a current (2,000 kW, DC power supply) was generated by an arc heater to heat a working gas composed of air. The working gas expanded due to heating, and an air flow with a high heat content was generated inside the measurement chamber. The test piece was heated by the generated airflow. The heating rate was 4.75 MW / m ² , and the heating time was 25 seconds.

The temperature of the test piece during heating was measured.
Specifically, the surface temperature of the bottom surface of the test body and the internal temperature at distances of 5 mm, 10 mm, and 15 mm from the bottom surface of the test body were measured, respectively. The surface temperature was measured from the infrared intensity using a radiation thermometer. The internal temperature was measured by a thermocouple inserted inside the test piece.
The measurement results are shown in the graph of FIG.
FIG. 4 is a graph showing the result of the arc heating test (temperature of the test piece). The horizontal axis represents the distance from the bottom surface (unit: mm), and the vertical axis represents the temperature (surface temperature or internal temperature, unit: ° C.). show.

Further, before and after the arc heating test, the mass of the test piece was measured, and the rate of decrease in mass (unit: kg / (sec · m ² )) was calculated. The results are shown in Table 1 below.

<Example 2>
A composite (carbon fiber content: 56) in which short carbon fibers (diameter: about 10 μm, length: about 30 μm) are randomly dispersed in PEEK (melting point: 343 ° C., MFR: 20 g / 10 minutes) which is a matrix resin. .5% by mass) was produced by injection molding. The 5% mass reduction temperature and thermal deformation temperature of the matrix resin used in Example 2 under nitrogen are as follows.
・ 5% mass reduction temperature of matrix resin under nitrogen: 556 ° C
・ Thermal deformation temperature of matrix resin: 152 ℃
Injection molding was carried out using an injection molding machine (ROBOSHOT a-S100iA manufactured by FANUC) in the following procedure.
First, in the injection molding machine, the cylinder temperature was set to 370 ° C., 380 ° C., 390 ° C. and 390 ° C. from the hopper side toward the nozzle, and the temperature was raised.
Next, a mixed resin in which short carbon fibers were dispersed was prepared in PEEK dried in an atmosphere of 150 ° C. for 2 hours, and the prepared mixed resin was put into a hopper of an injection molding machine.
The mixed resin was melted and weighed at a screw rotation speed of 100 rpm and a back pressure of 5 MPa. Then, the molten mixed resin was injected into the mold under the conditions of an injection pressure of 100 MPa, an injection speed of 60 mm / sec, a holding pressure of 15 MPa, and a cooling time of 20 seconds. After a cooling time of 20 seconds had elapsed, the solidified mixed resin was taken out from the mold and used as a complex.
The porosity of the produced complex was determined by the method described above and found to be 0.5%. The thermal deformation temperature of the complex was 290 ° C.
From the produced complex, a cylindrical test piece having a diameter of 20 mm and a height of 30 mm was hollowed out and subjected to the same arc heating test as in Example 1. The various results of the arc heating test are shown in the graph of FIG. 4 and Table 1 below.

<Summary of evaluation results>
Looking at the graph of FIG. 4, the internal temperature at a distance of 5 mm from the bottom surface of the test piece was about 700 ° C. lower in Example 1 than in Example 2.
Further, looking at Table 1 above, in Example 1, the value of the mass reduction rate was smaller than that in Example 2.
From the above results, Example 1 was superior in heat resistance to Example 2.
The entire contents of the specification, claims, abstract and drawings of Japanese Patent Application No. 2020-063142 filed on March 31, 2020 are cited here as disclosure of the specification of the present invention. It is something to incorporate.

1: Complex 2: Layer 3: Long fiber 4: Matrix resin 5: Striatum

Claims

With multiple stacked layers,
Inside the layer, a plurality of long fibers arranged in parallel in a direction orthogonal to the thickness direction of the layer are provided.
The long fibers arranged in the nth layer and the long fibers arranged in the n + 1th layer intersect, where n is a positive integer.
The layer has a matrix resin containing a thermoplastic resin and has
A complex having a porosity of 3 to 20%.
The complex according to claim 1, wherein the long fibers are carbon fibers.
The 5% mass reduction temperature of the matrix resin under nitrogen is 150 ° C. or higher.
The complex according to claim 1 or 2, wherein the matrix resin has a thermal deformation temperature of 100 ° C. or higher.
The complex according to claim 3, wherein the thermal deformation temperature is 150 ° C. or higher.
The complex according to any one of claims 1 to 4, wherein the thermoplastic resin contains an aromatic polyetherketone.
The complex according to claim 5, wherein the aromatic polyetherketone is a polyetheretherketone.
The complex according to any one of claims 1 to 6, wherein the long fibers have a diameter of 1 to 20 μm.
The complex according to any one of claims 1 to 7, wherein the content of the long fibers is 20 to 80% by mass.
The method for producing a composite according to any one of claims 1 to 8, wherein the composite has a matrix resin containing a thermoplastic resin and a plurality of long fibers, and the plurality of long fibers are linear. Using the linear bodies arranged in the length direction of the body, the linear bodies are arranged in one direction and melt-pressed, and then another linear body is placed adjacent to the linear body after the melt-pressing. A second layer adjacent to the layer is formed in the same manner except that one layer in the composite is formed by arranging them in parallel, melting and pressing, and then changing the direction of the linear body. A method for producing a complex, which comprises repeating the layer formation arbitrarily.
The manufacturing method according to claim 9, wherein the long fibers are continuous fibers.