JP2007242654A - Overheat protection element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an overheat protection element in which the trip temperature for interrupting a current when the circuit is overheated is prevented from differing for every element, and occurrence of chattering can be suppressed; and to provide its manufacturing method. <P>SOLUTION: The overheat protection element comprises a pair of conductive metal foils 1, and a macromolecular matrix layer 10 sandwiched between the pair of conductive metal foils 1. A plurality of recesses 3 for receiving the macromolecular matrix layer 10 are formed in the contact face 2 of each metal foil 1, and the contact face 2 is roughened in the metal foil 1 touching the macromolecular matrix layer 10. The macromolecular matrix layer 10 is admixed with insulating fine particles 11, and conduction is ensured through contact of the pair of conductive metal foils 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an overheat protection element that protects circuits, batteries, components, and the like of electrical equipment and a method for manufacturing the same.

Although not shown, the conventional overheat protection element includes a pair of conductive metal foils and a conductive polymer matrix layer sandwiched between the pair of metal foils, and a predetermined electric circuit or electronic circuit. Built-in to demonstrate the conduction function. In the polymer matrix layer, conductive resin and conductive fine particles are dispersed and blended (see Patent Documents 1 and 2).
Such an overheat protection element has a particularly low resistance value at room temperature, a sufficiently high rate of change between the room temperature resistance value and the resistance value during operation, and a small change in resistance value during repeated operation. Is required as a characteristic.

However, the conventional overheat protection element has a room temperature resistance value that increases due to repeated operations, and the conductive polymer matrix layer is sandwiched between a pair of metal foils. It has an inconvenient feature of functioning as an internal resistor.
In view of such problems, there has been proposed an overheat protection element in which a pair of metal foils serving as electrodes are in contact with each other when energized, and when the circuit is overheated, heat is detected and the pair of metal foils are separated to cut off current. .
JP 2006-024863 A JP 2005-347480 A

  Since the proposed overheat protection element is configured as described above, the polymer matrix layer can be prevented from becoming a circuit resistance. However, since the contact surface with which the metal foil contacts is simply a flat surface, a slight bias of expansion occurs when the ambient temperature rises due to distortion during molding of the polymer matrix layer, and as a result, the current is cut off when the circuit overheats. There is a possibility that the trip temperature to be different is different for each element. Furthermore, chattering in which an energized state and an insulated state occur alternately occurs near the trip temperature, which is inappropriate as an overheat protection element.

  The present invention has been made in view of the above, and provides an overheat protection element capable of suppressing the occurrence of chattering or a trip temperature at which a current is interrupted when a circuit is overheated, and a method for manufacturing the same. The purpose is that.

In the present invention, in order to solve the above-described problem, a polymer matrix is sandwiched between a plurality of conductive electrode bodies, and the plurality of electrode bodies are brought into contact with each other at room temperature so that they can conduct electricity. When the temperature rises, the polymer matrix is expanded and separated,
It is characterized in that the contact surface of the electrode body is roughened and insulating fine particles are blended in the polymer matrix.

  In addition, a retention part for the polymer matrix is formed on the contact surface of the electrode body, and the area ratio is set to 25 to 80% of the contact surface. The retention part is within the range of the thickness of the electrode body × 40 to 70%. It is preferable to form a recess at a depth.

Moreover, it is preferable that each electrode body is made of nickel, copper, or an alloy thereof, and the surface roughness Ra on the contact surface of the electrode body is 0.5 to 50 μm.
The polymer matrix preferably has a crystalline thermoplastic polymer of 70 wt% or more, and the insulating fine particles are spherical silica or silicone fine particles, and the average particle size is 0.1 to 5.0 μm.

Further, in the present invention, in order to solve the above-described problem, a polymer matrix is sandwiched between a plurality of conductive electrode bodies, and the plurality of electrode bodies are brought into contact with each other at room temperature so that they can conduct electricity. A method of manufacturing an overheat protection element that expands and separates a polymer matrix at a time when the temperature rises,
The contact surface of each electrode body is roughened, and insulating fine particles are blended in the polymer matrix.

In addition, a retention part for the polymer matrix is formed on the contact surface of the electrode body, and the area ratio is set to 25 to 80% of the contact surface. The retention part is within the range of the thickness of the electrode body × 40 to 70%. It is good to form a dent with depth.
Each electrode body is preferably made of nickel, copper, or an alloy thereof, and the surface roughness Ra on the contact surface of the electrode body is preferably 0.5 to 50 μm.
Further, the polymer matrix preferably has a crystalline thermoplastic polymer of 70 wt% or more, the insulating fine particles are silicone fine particles, and the average particle size is 0.1 to 5.0 μm.

Furthermore, a polymer matrix is sandwiched between a plurality of conductive electrode bodies so that the plurality of electrode bodies can be brought into contact with each other at room temperature to be conductive, and when the temperature rises above room temperature, the polymer matrix is formed. To inflate and separate,
A retention portion for the polymer matrix may be formed on the contact surface of the electrode body, the contact surface of the electrode body may be roughened, and insulating fine particles may be blended in the polymer matrix.

  According to the present invention, since the contact surface of the electrode body is roughened and the insulating matrix is blended in the polymer matrix, the trip temperature at which the current is interrupted when the circuit is overheated is different for each element, or chattering occurs. There is an effect that can be suppressed.

  Further, a retention portion for the polymer matrix is formed on the contact surface of the electrode body, and the area ratio is set to 25 to 80% of the contact surface, and the retention portion is within the range of the thickness of the electrode body × 40 to 70%. If the recess is formed at a depth, the length (distance) between the electrode bodies can be secured stably for a long period of time, and the possibility of short-circuiting during a long period of conduction can be eliminated. Moreover, it can prevent the expansion of the polymer matrix and prevent the initial resistance value from increasing from the beginning.

  Furthermore, if each electrode body is made of nickel, copper, or an alloy thereof, and the surface roughness Ra on the contact surface of the electrode body is 0.5 to 50 μm, excellent conductivity can be obtained relatively inexpensively, In addition, chattering in which an energized state and an insulated state occur alternately can be prevented.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, an overheat protection element in this embodiment includes a pair of conductive metal foils 1 and a pair of the metal foils 1 facing each other. And an expandable insulating polymer matrix layer 10 that is bonded and sandwiched between the metal foils 1, and is incorporated into a predetermined electric circuit or electronic circuit such as a computer or an automobile, and directly between the pair of metal foils 1. Demonstrates a conduction function by contact.

  The pair of metal foils 1 and the polymer matrix layer 10 are each formed in a flat rectangular shape, each metal foil 1 is formed thin by rolling or the like, and the polymer matrix layer 10 is formed relatively thick. .

  The plurality of metal foils 1 are formed using nickel, copper, or an alloy thereof that is less likely to rust, and a part of the polymer matrix layer 10 is formed on the contact surface 2 that contacts the opposing metal foil 1. A plurality of staying portions 3 to be stayed are recessed by an etching method or the like, and a lead wire 5 for circuit connection is connected to a non-contact surface 4 that does not contact the polymer matrix layer 10 and functions as an electrode. Of the plurality of metal foils 1, the contact surface 2 of at least one metal foil 1 is roughened into rough and random irregularities.

  The plurality of staying portions 3 have an area ratio in the range of 25 to 80% of the contact surface 2 and are formed to be recessed from the contact surface 2 at a depth in the range of the thickness of the metal foil 1 x 40 to 70%. It functions to fit into a part of the polymer matrix layer 10 and increase its expansion. The area ratio of the staying portion 3 is in the range of 25 to 80% of the contact surface 2, and the depression is formed from the contact surface 2 at a depth in the range of the thickness of the metal foil 1 x 40 to 70%. This is because if it comes off, it will hinder the expansion of the polymer matrix layer 10 and the initial resistance value will be high from the beginning, which will not be practical.

  The surface roughness Ra on the contact surface 2 of the metal foil 1 is in the range of 0.5 to 50 μm from the viewpoint of improving the conductivity.

  The polymer matrix layer 10 is formed into a sheet containing 70 wt% (wt%) or more of a crystalline thermoplastic polymer, and a large number of incompatible insulating fine particles 11 are blended. As the polymer matrix layer 10, for example, polyethylene or maleic acid-modified EPR that can obtain an appropriate expansion coefficient is used as a material.

  The insulating fine particles 11 are made of, for example, spherical silica or silicone fine particles, and have an average particle diameter of 0.1 to 5.0 μm, preferably 0.3 to 2.0 μm. It functions to improve rigidity. The average particle diameter of the insulating fine particles 11 is in the range of 0.1 to 5.0 μm. When the average particle diameter is less than 0.1 μm, the viscosity increases during the dispersion of the resin or a problem occurs in moldability. This is because the cost increases. Conversely, when the average particle diameter exceeds 5.0 μm, the strength of the overheat protection element becomes insufficient when used for a long period of time.

  In the above, when manufacturing an overheat protection element, first, a pair of metal foils 1 is prepared, and a plurality of dwelling portions 3 for the polymer matrix layer 10 are formed on the contact surface 2, respectively. The contact surface 2 is roughened into irregularities.

  Further, before and after the processing of the metal foil 1, the pellet-shaped polymer matrix and the insulating fine particles 11 are set in a jet mill or the like to adjust the particle size, and the polymer matrix and the insulating fine particles 11 are mixed with the mixer. The polymer matrix layer 10 is manufactured by mixing with stirring and kneading with a pressure kneader adjusted to a predetermined temperature, setting in a calendering machine, and sheeting with the calendering machine.

  When the pair of metal foils 1 and the polymer matrix layer 10 are manufactured in this way, the polymer matrix layer 10 is sandwiched between the pair of metal foils 1 and set in a press molding machine. If the laminate is manufactured, and then the laminate is irradiated with an electron beam to crosslink the polymer matrix and the lead wire 5 is connected to the non-contact surface 4 of each metal foil 1, an overheat protection element can be manufactured. .

  The overheat protection element manufactured in this way is incorporated in a predetermined electric circuit or electronic circuit, and a pair of metal foils 1 come into contact with each other at room temperature so that the circuit can be conducted, and when the temperature rises higher than room temperature That is, at the time of overheating, the polymer matrix layer 10 expands and separates to interrupt the current. Such an overheat protection element can be widely used as a fuse for protection of primary batteries, secondary batteries, automobile motors, speakers, computer circuits, and the like.

  According to the above, the contact surface 2 of the metal foil 1 is not flat but roughened to moderate irregularities, and the insulating fine particles 11 are blended in the polymer matrix layer 10, so that the circuit has a temperature higher than normal temperature. The trip temperature for interrupting the current during overheating of the device does not differ for each element, and a stable initial resistance value and steep trip characteristics can be obtained. Further, since chattering in which the energized state and the insulated state occur alternately near the trip temperature can be suppressed and prevented, an appropriate overheat protection element can be provided.

  In addition, since the insulating fine particles 11 are blended in the polymer matrix, it becomes possible to improve the stability of the overheat protection element after a trip. Furthermore, since the retention part 3 which secures the volume of the polymer matrix layer 10 to some extent is formed in each metal foil 1 to increase the expansion width of the polymer matrix layer 10 when the overheat protection element is overheated, for example, the overheat protection element Even if the thin polymer matrix layer 10 is softened by its own heat, the entire distance between the metal foils 1 can be secured stably for a long time, and a short circuit occurs when approaching for a long time. There is no fear.

  In the above-described embodiment, the contact surface 2 of one metal foil 1 is roughened into rough and random irregularities. However, the contact surface 2 of each metal foil 1 may be roughened into rough and random irregularities. Moreover, although the several retention part 3 was recessedly formed in the contact surface 2 of each metal foil 1, it is not limited to this at all, For example, you may form the single retention part 3 into a recess. Furthermore, the polymer matrix of the polymer matrix layer 10 is not particularly limited to one type, many types, or a plurality of types as long as it has insulating properties.

Examples of the overheat protection element and the method for manufacturing the same according to the present invention will be described below together with comparative examples.
Example 1
First, in order to produce a polymer matrix layer and insulating fine particles, polyethylene (Idemitsu Petrochemical: trade name 548B) 92 wt%, maleic acid-modified EPR (JSR: trade name T-7741P) 7 wt%, silicone fine particles (GE Toshiba Silicone: trade name XC99-A8808) 1 wt% was prepared.

  After preparing the material of the polymer matrix layer and the insulating fine particles in this way, the particle size is adjusted to 16 to 100 mesh from the pellets in the form of supply by a jet mill, and this polymer matrix and the insulating fine particles are put into a super mixer (manufactured by Kawata). The mixture is mixed and stirred and kneaded by a pressure kneader adjusted to a temperature of 180 ° C. to produce a kneaded product. The kneaded product is set in a calendering machine and seated, and a polymer matrix having a thickness of 50 μm. A layer was produced.

Next, a polymer matrix layer is sandwiched between a pair of roughened metal foils shown in FIG. 2 and Table 1 and set in a press molding machine, and heated by this press molding machine at 250 ° C. and 10 kgf / cm ^2. A laminate having a thickness of 250 μm was produced by pressurization, and then the polymer matrix was crosslinked by irradiating the laminate with an electron beam of 30 MRad by an electron beam crosslinking apparatus, thereby producing an overheat protection element. Each metal foil was a nickel foil having a thickness of 125 μm, and its surface roughness Ra was 2.0 μm.

Example 2
In order to produce a polymer matrix layer and insulating fine particles, polyethylene (Idemitsu Petrochemical: trade name 548B) 92 wt%, maleic acid modified EPR (JSR: trade name T-7741P) 7 wt%, silicone fine particles (GE) Toshiba Silicone Co., Ltd. product name XC99-A8808) 1 wt% was prepared. The dimensional ratio of the pair of metal foils was changed as shown in Table 1. The other parts were the same as in Example 1.

Example 3
In order to produce a polymer matrix layer and insulating fine particles, polyethylene (Idemitsu Petrochemical: trade name 548B) 92 wt%, maleic acid-modified EPR (JSR: trade name T-7741P) 7 wt%, silicone fine particles (GE) Toshiba Silicone product name: Tospearl 145) 1 wt% was prepared. The dimensional ratio of the pair of metal foils was changed as shown in Table 1. The other parts were the same as in Example 1.

Example 4
In order to produce the polymer matrix layer and the insulating fine particles, polyethylene (Idemitsu Petrochemical: trade name 548B) 92 wt%, maleic acid-modified EPR (JSR: trade name NO903HC) 7 wt%, silicone fine particles (GE Toshiba Silicone) Product name: XC99-A8808) 1 wt% was prepared. The dimensional ratio of the pair of metal foils was changed as shown in Table 1. The other parts were the same as in Example 1.

Example 5
In order to produce a polymer matrix layer and insulating fine particles, the materials are polyethylene (Idemitsu Petrochemical: trade name 548B) 92 wt%, maleic acid modified EPR (JSR: trade name NO903HC) 7 wt%, silicone fine particles (GE Toshiba Silicone). Product name: XC99-A8808) 1 wt% was prepared. The dimensional ratio of the pair of metal foils was changed as shown in Table 1. The other parts were the same as in Example 1.

Comparative Example First, 93 wt% of polyethylene (made by Idemitsu Petrochemical Co., Ltd .: trade name 548B) and 7 wt% of maleic acid-modified EPR (made by JSR: T-7741P) are selected as materials, and this material is supplied from pellets that are supplied by a jet mill. The particle size was adjusted to 16 to 100 mesh, these were put into a super mixer (manufactured by Kawata), mixed and stirred, and kneaded by a pressure kneader adjusted to a temperature of 180 ° C. to produce a kneaded product. When the kneaded material was manufactured in this way, the kneaded material was set in a calendering machine and sheeted to manufacture a sheet having a thickness of 50 μm.

Next, a sheet is sandwiched between a pair of metal foils shown in Table 1 and set in a press molding machine, and this press molding machine is heated and pressed under the conditions of 250 ° C. and 10 kgf / cm ² to produce a laminate having a thickness of 250 μm. Thereafter, the laminate was irradiated with an electron beam of 30 MRad by an electron beam cross-linking device to cross-link the polymer composition of the sheet, thereby producing an overheat protection element. Unlike the case of an Example, each metal foil was comprised in the structure which does not have a roughening process and a retention part.

  When the overheat protection elements of Examples and Comparative Examples were respectively produced, the characteristics and RT curves of each overheat protection element were measured and summarized in Tables 2 to 4 and FIGS.

  When measuring the characteristics of the overheat protection element, connect an electric wire to the overheat protection element, connect the other end of the electric wire to a resistance measuring instrument, place the connected overheat protection element in an oven, and measure the resistance value. Started. The resistance value was measured by increasing the temperature sequentially from 20 ° C. every 10 ° C., and the temperature was increased to 160 ° C. When the temperature reached 160 ° C. in this way, the temperature was maintained and the resistance value state of the overheat protection element was observed. When the insulation could not be maintained, the measurement was stopped at that time. The resistance value in the insulation state was measured with a limit of 35000Ω.

  The resistance value in the trip state was measured about every 24 hours and observed until 1000 hours were reached (equivalent to the aging test of UL1434). Then, the overheat protection element which did not cause a problem was allowed to stand at room temperature for 1 hour, and then the RT curve was measured.

  The RT curve was measured as follows. That is, the resistance value was measured by increasing the temperature sequentially from 20 ° C. every 10 ° C., and the temperature was increased to 160 ° C. When the temperature reached 160 ° C., the temperature was sequentially decreased every 10 ° C. and measurement was continued until 20 ° C., and the resistance value when the temperature returned to 20 ° C. was called a relaxation resistance value.

In the case of Examples 1 to 5, a good insulation state was shown, and there was no problem even in the RT measurement after 1000 hours.
On the other hand, in the case of the comparative example, after reaching the trip temperature, the insulation state is not maintained after about 50 hours, and it is confirmed that chattering is performed, and after 250 hours, all are in the energized state. It was confirmed.

It is a section explanatory view showing typically an embodiment of an overheat protection element concerning the present invention. It is a perspective explanatory view showing typically the example of the overheat protection element concerning the present invention. It is a graph which shows the long-term stability in the Example of the overheat protection element which concerns on this invention. It is a graph which shows the long-term stability in the comparative example of the overheat protection element which concerns on this invention. It is a graph which shows the RT curve in Example 1 of the overheat protection element which concerns on this invention. It is a graph which shows the RT curve in Example 2 of the overheat protection element which concerns on this invention. It is a graph which shows the RT curve in Example 3 of the overheat protection element which concerns on this invention. It is a graph which shows the RT curve in Example 4 of the overheat protection element which concerns on this invention. It is a graph which shows the RT curve in Example 5 of the overheat protection element which concerns on this invention.

Explanation of symbols

1 Metal foil (electrode body)
2 Contact surface 3 Retaining part 10 Polymer matrix layer (polymer matrix)
11 Insulating fine particles

Claims (8)

A polymer matrix is sandwiched between a plurality of conductive electrode bodies so that the plurality of electrode bodies can be brought into contact with each other at room temperature to be conductive, and the polymer matrix is expanded when the temperature rises above room temperature. An overheat protection element that is separated by
An overheat protection element characterized in that the contact surface of the electrode body is roughened and insulating fine particles are blended in a polymer matrix.   A retention portion for the polymer matrix is formed on the contact surface of the electrode body, and the area ratio is set to 25 to 80% of the contact surface, and the retention portion has a depth in the range of the thickness of the electrode body × 40 to 70%. The overheat protection element according to claim 1, wherein the overheat protection element is formed as a depression.   The overheat protection element according to claim 1 or 2, wherein each electrode body is made of nickel, copper, or an alloy thereof, and the surface roughness Ra on the contact surface of the electrode body is 0.5 to 50 µm.   The superheat according to claim 1, 2, or 3, wherein the polymer matrix has a crystalline thermoplastic polymer of 70 wt% or more, the insulating fine particles are silicone fine particles, and the average particle size is 0.1 to 5.0 µm. Protective element. A polymer matrix is sandwiched between a plurality of conductive electrode bodies so that the plurality of electrode bodies can be brought into contact with each other at room temperature to be conductive, and the polymer matrix is expanded when the temperature rises above room temperature. A method of manufacturing an overheat protection element that is separated by
A method for manufacturing an overheat protection element, characterized in that the contact surface of each electrode body is roughened and insulating fine particles are blended in a polymer matrix.   A retention portion for the polymer matrix is formed on the contact surface of the electrode body, and the area ratio is set to 25 to 80% of the contact surface. This retention portion is a depth in the range of the thickness of the electrode body × 40 to 70%. The method for manufacturing an overheat protection element according to claim 5, wherein the depression is formed by a step.   The method for manufacturing an overheat protection element according to claim 5 or 6, wherein each electrode body is made of nickel, copper, or an alloy thereof, and the surface roughness Ra on the contact surface of the electrode body is 0.5 to 50 µm. The superheat according to claim 5, 6 or 7, wherein the polymer matrix has a crystalline thermoplastic polymer of 70 wt% or more, the insulating fine particles are silicone fine particles, and the average particle size is 0.1 to 5.0 µm. A manufacturing method of a protection element.

Images