JPH04549B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an apparatus for detecting electrical properties of resin.

(Prior Art) In the production of reinforced resin products, it is already known that the degree of hardening of a matrix resin material impregnated into reinforcing fibers can be detected by electrical measurement. That is, during the curing reaction process of the resin material, electrical properties such as dielectric properties and electrical conductivity change, so by detecting these changes, the state of curing of the resin material can be known. Measurement of such electrical properties is performed using a pair of electrode plates, but for high-precision detection, the area of the electrode plates should be made sufficiently large, or the gap between the electrode plates should be made as small as possible. It is necessary to lower the impedance or electrical resistance between the electrodes. In reality, it is not practical to increase the area of the electrode plates, so in order to reduce the gap between the electrode plates,
Attempts have been made to insert or embed electrodes into the material to be measured. However, this method has a practical problem because the inserted or buried electrodes and their lead wires become product defects. Therefore, as shown in FIGS. 8 and 9, a pair of electrodes 2
0 and 21 are arranged in parallel at intervals on one side of an electrically insulating substrate 22, and the electrodes are applied directly or through a liquid resin permeable electrically insulating layer 23 such as glass cloth to the surface of the resin to be measured 24, and electrically It has been proposed to measure physical properties. FIG. 8 shows the case where the reinforcing fibers of the resin to be measured have conductivity, and in order to prevent short circuits between the electrodes, the measurement is carried out through a glass cloth or the like through which the resin easily permeates. FIG. 9 shows a case where the reinforcing fiber is an insulator, and the electrode plate is directly applied to the surface of the resin to be measured. 25 indicates a metal forming jig.

(Problems to be Solved by the Invention) The electrical equivalent circuit of the above-mentioned device having a pair of parallel electrodes on an electrically insulating substrate shown in FIGS. 8 and 9 is shown in FIG. The conductive reinforcing fiber layer 24 of FIG. 9 or the metal forming jig 2 of FIG.
5 acts as a pseudo electrode. Electrode 2 is required for accurate detection of changes in electrical properties during resin curing reaction.
0,21 needs to be several tens of mm square, and one side of the board 22 is about 100 mm. Such a large-sized device is very inconvenient to use when manufacturing small parts or when the product has a curved shape, and it also poses a problem when trying to minimize the bonding marks of the electrodes. Furthermore, in the measurement results obtained using a device with parallel electrodes, the peak may be reversed and show a trough-like change where it should normally show a peak, and accurate measurements may not be possible at this peak portion. . The reason for this is not clear, but in the case of devices with parallel electrodes, the opposing electrode surface is a carbon fiber layer that is the reinforcing fiber of the molding material, or a metal molding jig, and the shape is irregular. This seems to be due to the fact that the area is extremely large compared to the area of .

(Means for Solving the Problems) The present invention solves the above-mentioned problem of parallel electrodes, namely, that when trying to accurately measure changes in the electrical properties of resin, the detection device becomes large, and the measured value In order to solve the problem of inversion of the peak portion in , one or more layers of counter electrodes are arranged in a stacked manner so as to face each of the parallel electrodes. Between each of the parallel electrodes and the counter electrode, and between the counter electrodes, an electrically insulating layer permeable to liquid resin, such as a thin layer of glass cloth or ceramic fiber cloth, is arranged. Then, in each of the opposing electrodes, every other electrode is connected to each other when viewed in the stacking direction. Further, the uppermost counter electrode is connected to the electrode on the substrate of the adjacent stacked row. External lead wire terminals are provided on the electrically insulating substrate on the side opposite to the parallel electrodes, and these terminals are connected to the parallel electrodes. It is preferable to form holes for resin penetration in each counter electrode, and if the reinforcing fiber is conductive such as carbon-based, an electrically insulating layer permeable to liquid resin is placed under the lowest layer of the counter electrode. It is preferable to further arrange.

(Function) When using the detection device having the above configuration of the present invention, if the reinforcing fibers of the object to be measured are non-conductive, the counter electrode should be directly connected to the surface, and the reinforcing fibers of the object to be measured should be conductive. In the case of a liquid resin permeable electrical insulating layer, they are faced to each other through an electrically insulating layer permeable to a liquid resin. Since the fluid resin during the curing reaction permeates the electrical insulating layer between the opposing electrodes, the electrical properties of the resin can be measured by the electrical signal appearing between the electrodes. Since the connection between the electrodes is in the form of a plurality of capacitors connected in parallel, a larger capacitance can be obtained compared to measurement using a pair of parallel electrodes, and the electrodes can be made smaller accordingly. As an example, the electrical equivalent circuit of the embodiment of the present invention shown in FIG. 1 is a circuit in which a plurality of capacitors are connected in parallel as shown in FIG. The capacity of the entire device is 9/2Co. On the other hand, the 10th
If the capacitance of each capacitor in the electrical equivalent circuit of the conventional example shown in the figure is Co, which is the same as that of the embodiment of the present invention, the capacitance of the conventional device will be 1/2 Co. In other words, if conditions such as the electrode plate area are the same, the embodiment of the present invention has a capacity nine times larger by simple calculation, and the area of each electrode plate can be reduced by the increased capacitance. High precision and compactness can be achieved.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the present invention, in which a pair of electrodes 3 and 4 are provided on one surface of an electrically insulating substrate 1.
are arranged in parallel at intervals, and lead wire terminals 5 and 6 connected to each of these electrodes 3 and 4 are arranged on the opposite surface. A pair of counter electrodes 7 and 8 are disposed opposite to the electrodes 3 and 4 with a layer, such as a glass cloth layer 9, permeable to the fluid resin and having electrical insulation properties interposed therebetween. Furthermore, another pair of counter electrodes 10 and 11 are arranged with a glass cloth layer 12 in between, at positions facing each of the counter electrodes 7 and 8. The counter electrodes 10 and 11 are placed facing the surface of the reinforced resin product 14 with the glass cloth layer 13 in between. If the reinforcing fibers of the reinforced resin product 14 do not have electrical conductivity, the glass cloth layer 13 may be omitted. Electrodes 3, 7, 10 form one electrode stack array, and electrodes 4, 8, 11 form another electrode stack array. Electrode 3 is connected to counter electrodes 8 and 10, and electrode 4 is connected to counter electrodes 7 and 11.
It is connected to the. The thickness of the counter electrode plate is approximately 0.1mm.
The thickness of the glass cloth layer is very thin at 0.1 to 0.15 mm, and even when laminated, there is only a slight increase in the dimension in the thickness direction. Further, as described above, the electrical equivalent circuit of this embodiment is as shown in FIG. 6, and a large capacity can be achieved even if the temporary electrode area is reduced. In other words, it is possible to provide a highly accurate and compact detection device.

Further, FIG. 7 shows an electrical equivalent circuit in the case where the reinforcing fibers have no conductivity in this example. In the present invention, since a counter electrode is provided at a position facing the electrode arranged on the substrate, the pseudo electrode which is essential in the conventional example is not necessary. Therefore, even if the reinforcing fibers do not have electrical conductivity, the electrical properties can be detected without a molding jig or the like, or even if the resin is used alone.

As shown in FIG. 2, the terminals 5 and 6 on the substrate 1 are L-shaped, and the connections with the electrodes 3 and 4 are made through holes formed in the substrate 1. Counter electrodes 7, 8,
10 and 11 are substantially rectangular as shown in FIG. 3, and position lead pieces 16 are formed at both ends thereof, eccentric in the width direction from the center line 15 in the longitudinal direction of the rectangle. The electrodes can be arranged as shown in FIG. 2, the lead piece 16 can be folded back, and the desired connection can be completed with solder. If the lead piece 16 is made eccentric in the width direction, the position of the lead piece can be changed by turning the electrodes of the same shape over and using them, making the connection work convenient. Note that, as shown in FIG. 3, a large number of holes 17 are formed in the counter electrodes 7, 8, 10, and 11 for passage of the fluid resin.

Figures 4 and 5 show measurement results when only one layer of opposing electrodes is used in a conventional device consisting of only a pair of parallel electrodes and the device of the present invention.
Conditions such as electrode area and distance between electrodes are the same. FIG. 4 shows changes in the dielectric loss coefficient, which represents the degree of leakage current that is directly related to energy loss in the dielectric, and FIG. 5 shows changes in the interelectrode capacitance. Note that the graphs of the conventional example D ₂ and the graph of the present invention D ₁ correspond to the scales of D ₂ and D ₁ shown at the left end of the figure, respectively. As is clear from FIG. 4, according to the present invention, the dielectric loss coefficient can be detected with much higher sensitivity than the conventional device even if the counter electrode is only one layer, and the dielectric loss coefficient can be detected with much higher sensitivity than the conventional device. Noise (indicated by A, B, C, and D in FIG. 4) can also be almost eliminated. Furthermore, as shown in Fig. 5, in the conventional device, a V-shaped inverse peak sometimes appeared in the measured value of the interelectrode capacitance, but the present invention does not have such a problem and is highly accurate. It was found that capacitance changes can be detected. It has been experimentally confirmed that the above-mentioned effects of the present invention can be further improved by using a plurality of opposing electrodes.

(Effects) As described above, according to the present invention, counter electrodes are arranged at positions opposite to each of a pair of electrodes arranged in parallel with an interval on an electrically insulating substrate, and a liquid is injected between these electrodes. Since a resin-permeable electrical insulating layer is provided, its electrical equivalent circuit becomes one in which capacitors are connected in parallel as described above, and a large capacitance can be achieved with a small electrode area. The present invention provides an electrical property detection device. Furthermore, since each capacitor section is mostly composed of pairs of electrodes facing each other, it is possible to eliminate the problem of a reverse signal appearing at the peak of the measured value, which is thought to be caused by the shape and area of the electrodes being too large.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a resin electrical property detection device according to the present invention, Fig. 2 is an exploded perspective view thereof, Fig. 3 is a plan view showing an example of a counter electrode, and Fig. 4 is a measurement of dielectric loss coefficient. FIG. 5 is a chart showing the results of measuring the interelectrode capacitance. 6 is an electrical equivalent circuit of FIG. 1, FIG. 7 is an electrical equivalent circuit of another embodiment, FIGS. 8 and 9 are conventional detection devices, and FIG. 10 is an electrical equivalent circuit of FIG. Shows an electrical equivalent circuit. 1... Insulating substrate, 3, 4... Electrode, 7, 8,
10, 11... Counter electrode, 9, 12, 13... Electrical insulation layer, 14... Reinforced resin product.

Claims (1)

[Claims] 1. In a detection device that detects a change in the electrical properties of a resin by interposing the resin between electrodes to which a voltage is applied, a first electrode and a second electrode are arranged on one side of an electrically insulating substrate at a distance from each other. A third electrode is arranged in a position opposite to the first electrode, and a fourth electrode is arranged in a position opposite to the second electrode, with a liquid resin permeable electrical insulating layer interposed therebetween. the first electrode and the fourth electrode are placed in an electrically connected relationship with each other, the second electrode and the third electrode are placed in an electrically connected relationship with each other, and the substrate other than the substrate is placed in an electrically connected relationship. A resin electrical property detecting device including external lead wire terminals connected to the first electrode and the second electrode, respectively, on the side surfaces. 2. The detection device according to item 1 above, wherein holes for resin penetration are formed in the third and fourth electrodes. 3. The detection device according to item 1 or 2, wherein the electrically insulating layer permeable to liquid resin is constituted by a glass fiber layer. 4. In a device that detects the electrical properties of a resin by interposing the resin between electrodes to which a voltage is applied,
A pair of electrodes are arranged in parallel at intervals on one side of an electrically insulating substrate, and a plurality of opposing electrodes are arranged at positions opposite to these pairs of electrodes through an electrically insulating layer permeable to liquid resin. The electrodes are arranged in layers or laminated, and are arranged in overlapping positions in the lamination direction.
The electrodes on the farthest side when viewed from the electrically insulating substrate are electrically connected to each other every other electrode when viewed in the stacking direction, and the counter electrode at the top of each stacked row is connected to the electrode on the substrate of the adjacent stacked row. A resin electrical property detection device, characterized in that it is connected to an electrode. 5. The detection device according to item 4 above, wherein each of the opposing electrodes is formed with a hole for resin penetration.