JP7783846B2 - Stain prevention mat for induction cookers - Google Patents

Description

This invention relates to a stain-preventing mat for an induction cooker, and in particular to a stain-preventing mat for an induction cooker that prevents dirt from the bottom of a pot being heated, overflow, etc. from adhering to the top plate of the induction cooker.

Patent Document 1 shows a stain-preventing mat for induction cookers that is placed between the top plate of the cooker and the bottom of the pot.

Figure 3 is a plan view showing the external appearance of a conventional stain-preventing mat for an induction cooker when used in a general cooking heating device incorporating an induction cooker. Figure 4 is a diagram corresponding to the IV-IV line shown in Figure 3, and is a cross-sectional view showing a schematic diagram of the operating principle of an induction cooker and an enlarged cross-sectional view of a conventional stain-preventing mat for an induction cooker.

First, referring to Figure 3, induction cookers 13a and 13b are installed on the left and right sides of the front of the top plate 17 of the cooking heating device 61, and a heating wire heater 63 with nichrome wire embedded in the underside of the top plate 17 is installed behind the top plate 17. Note that depending on the model of cooking heating device 61, some may be equipped with induction cookers instead of the heating wire heater 63 (i.e., equipped with three induction cookers), while others may have only two induction cookers without the heating wire heater 63. An intake/exhaust panel 65 is also located on the back side of the top plate 17. This figure shows that a magnetically permeable, heat-resistant stain-preventing mat 51 is placed over the induction cooker 13b, and a pot 19 to be heated is placed on top of that.

For the schematic structure and heating principle of the induction cooker 13b, see Figure 4 (1). The magnetic field generating coil 14 that constitutes the induction cooker 13b is located below the top plate 17. When current flows through the magnetic field generating coil 14 by turning on a switch (not shown), magnetic field lines 15, as indicated by the two-dot chain lines, are generated around the magnetic field generating coil 14. These magnetic field lines 15 penetrate the top plate 17 and the stain-preventing mat 51, and also penetrate the bottom of the pot 19 placed on the top plate 17, forming a loop. Because the pot 19 is made of a material with a certain level of conductivity, the generation of these magnetic field lines 15 generates eddy currents 16 in the bottom of the pot. The eddy currents 16 thus generated are converted into heat by the electrical resistance of the bottom of the pot 19, raising the temperature of the bottom of the pot. This allows the food placed in the pot 19 to be heated without using fire. Furthermore, when the power supply to the magnetic force generating coil 14 is stopped, the magnetic field lines 15 disappear, and the eddy currents 16 generated in the bottom of the pot 19 also disappear. As a result, the temperature of the bottom of the pot 19 drops, and the heating state ends. A temperature sensor 18 is attached below the top plate 17. The temperature sensor 18 monitors the temperature of the top plate 17, and if the temperature of the top plate 17 rises abnormally due to empty heating, etc., a control device (not shown) cuts off the power supply and stops heating.

Referring to Figure 4(2), which shows an enlarged view of the stain-prevention mat 51 at the "Z" portion of Figure 4(1), and Figure 3, the structure of the stain-prevention mat 51 is shown. The stain-prevention mat 51 is made of a woven fabric 53 made of glass fiber, which is permeable to magnetic lines of force, with water-impermeable, heat-resistant silicone 54a and 54b applied to both sides of the woven fabric 53, which is then cut into a circular shape to form a sheet 52. The stain-prevention mat 51 has cushioning properties due to the use of woven fabric 53 as its central material. Furthermore, because water-impermeable, heat-resistant silicone 54a and 54b are applied to both sides, the entire stain-prevention mat 51 is water-impermeable and heat-resistant.

When used, the stain-prevention mat 51 prevents dirt from adhering to the bottom of the pot 19 or food splashes from directly adhering to the top plate 17, keeping it in a beautiful condition and eliminating the need for cleaning. Furthermore, to prevent its use from affecting the temperature sensor measurements of the induction cooker, the thermal resistance of the sheet 52 is set within a specified range, minimizing the impact on the temperature sensor that detects the temperature of the top plate. As a result, the risk of malfunctions occurring when using the induction cooker is reduced.

JP 2009-140887 A

When a conventional stain-preventing mat 51 such as that described above in Patent Document 1 is placed on an induction cooktop 13a or 13b and heated with a pot 19 on the mat 51, the mat 51 comes into contact with the induction cooktop 13a or 13b at high temperatures. The silicones 54a and 54b in the mat 51 have a chemical structure similar to that of glass, the material of the top plate 17. This can result in adhesion between the silicone 54a or 54b located on the top plate 17 and the top plate 17, resulting in the silicone 54a or 54b remaining on the top plate 17. If the adhesion is mild, the silicone 54a or 54b can be easily removed by rubbing the adhered area with fingers or a sponge containing detergent. However, if the adhesion is strong, the mat 51 itself may become stuck to the top plate 17, making it impossible to remove, potentially resulting in the silicone 54a or 54b becoming a stain on the top plate 17 itself. Furthermore, if the stain-prevention mat 51 is strongly adhered, there is a risk that the mat 51 will tear at the adhered portion when attempting to remove it from the top plate 17. In other words, not only the silicone 54a or 54b that constitutes the stain-prevention mat 51, but also the glass fibers will remain on the top plate 17.

This invention was made to solve the above-mentioned problems, and aims to provide a stain-prevention mat for induction cooktops that is less likely to stick or tear.

In order to achieve the above object, the invention described in claim 1 is a stain prevention mat for an induction cooker that is used by being sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker, which comprises a heat-resistant sheet body that is permeable to magnetic lines, the sheet body having a maximum tear strength of 5.0 kN/m or more and 200.5 kN/m or less, and the sheet body is made of glass fiber and silicone formed on both sides of the glass fiber .

With this configuration, the stain prevention mat has a predetermined tear strength, and the effect 1 is obtained in that the mat has predetermined heat resistance and strength, as well as flexibility .

The invention described in claim 2 is the same as the invention described in claim 1, except that the thickness of the sheet body is 0.74 mm or less.

This configuration achieves effect 2, which is to reduce the impact on the temperature sensor that detects the temperature of the top plate.

The invention described in claim 3 is the configuration of the invention described in claim 1 or claim 2, wherein the sheet body comprises a sheet-like material made of heat-resistant fibers and a water-impermeable coating material formed on both sides of the material, the material having a thickness of 0.04 mm to 0.42 mm, the coating material having a coating weight of 5 g/ ^m2 to 50 g/ ^m2 on the front side , and the coating material having a coating weight of 15 g/m2 to 520 g/m2 ^on the back ^side .

This configuration provides both cushioning and a predetermined tear strength, while also reducing the impact on the temperature sensor that detects the temperature of the top plate, resulting in effect 3.

The invention described in claim 4 is the structure of the invention described in claim 3, wherein the total coating amount of the coating material on the sheet body is 20 g/m ² or more and 570 g/m ² or less.

This configuration achieves effect 4, which further reduces the impact on the temperature sensor that detects the temperature of the top plate.

The invention described in claim 5 is the same as the invention described in claim 1 or claim 2, in which the sheet body comprises a sheet-like material made of heat-resistant fibers and a water-impermeable coating material formed on both sides of the material, the material having a thickness of 0.04 mm or more and 0.42 mm or less, the coating material having a coating thickness on the front surface of 2.9 μm or more and 28.6 μm or less , and the coating material having a coating thickness on the back surface of 8.6 μm or more and 297.6 μm or less .

This configuration provides effect 5, which combines cushioning properties with a predetermined tear strength and reduces the impact on the temperature sensor that detects the temperature of the top plate.

The invention of claim 6 is the structure of the invention of claim 5, wherein the total coating thickness of the coating material on the sheet is 11.5 μm or more and 326.2 μm or less.

This configuration achieves effect 6, which further reduces the impact on the temperature sensor that detects the temperature of the top plate.

The invention described in claim 7 is a stain-preventing mat for an induction cooker that is used by sandwiching it between the top plate of the induction cooker and the bottom of a pot heated by the induction cooker. The mat is made of a heat-resistant sheet that is permeable to magnetic lines, and the sheet has a maximum tear strength of 15.0 kN/m or more and 200.5 kN/m or less. The sheet is made of a sheet-like material made of heat-resistant fibers and a water-impermeable coating material formed on both sides of the material, and the coating material contains silicone, so that the silicone of the sheet does not stick to the top plate of the induction cooker during use.
With this configuration, an effect 7 of providing a predetermined tear strength can be obtained.
The invention described in claim 8 is a stain-preventing mat for an induction cooker that is used by being sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker, and is made of a heat-resistant sheet body that is permeable to magnetic lines, and the sheet body has a maximum tear strength of 5.0 kN/m or more and 200.5 kN/m or less and a thickness of 0.74 mm or less, and the sheet body is made of a sheet-like material made of heat-resistant fibers and a water-impermeable coating material formed on both sides of the material, the material containing glass fiber, the coating material containing silicone, and the material having a thickness of 0.04 mm or more and 0.42 mm or less.
With this configuration, an effect 8 of providing a predetermined tear strength can be obtained.
The invention of claim 9 provides a stain-preventing mat for an induction cooker that is used by being sandwiched between the top plate of the induction cooker and the bottom of a pot heated by the induction cooker, the mat comprising a heat-resistant sheet body that is permeable to magnetic lines, the sheet body having a maximum tear strength of 5.0 kN/m or more and 200.5 kN/m or less, the sheet body comprising a sheet-like material made of heat-resistant fibers and a water-impermeable coating material formed on both sides of the material, the material including glass fiber and the coating material including silicone, the sheet body having a thickness of 0.74 mm or less, the material having a thickness of 0.04 mm or more and 0.42 mm or less, the coating material having a coating thickness (thickness after drying) of 2.9 μm or more and 28.6 μm or less on the front side and a coating thickness (thickness after drying) of 8.6 μm or more and 297.6 μm or less on the back side .
With this configuration, an effect 9 of providing a predetermined tear strength can be obtained.

As described above, the invention of claim 1 provides the above-mentioned effect 1, so that the stain-preventing mat is less likely to stick or tear when peeled off from the top plate. In addition, the stain-preventing mat has a predetermined strength and is excellent in heat resistance, impact resistance, and flexibility.

The invention described in claim 2 achieves the effect of the invention described in claim 1 as well as effect 2 described above, thereby reducing the risk of problems occurring when using an induction cooktop.

The invention described in claim 3 achieves the effects of the invention described in claim 1 or claim 2, as well as effect 3 described above, making it less likely to damage the top plate or pot, preventing sticking or tearing, and less likely to interfere with the proper operation of the temperature sensor.

The invention described in claim 4 achieves the effect of the invention described in claim 3 as well as effect 4, so the proper operation of the temperature sensor is not hindered.

The invention described in claim 5 achieves the effects of the invention described in claim 1 or claim 2, as well as effect 5 described above, making it difficult for the top plate or pot to be damaged, preventing sticking or tearing, and not interfering with the proper operation of the temperature sensor.

The invention described in claim 6 achieves the effect of the invention described in claim 5 as well as the above-mentioned effect 6, so it does not interfere with the proper operation of the temperature sensor.

The invention described in claim 7 achieves the above-mentioned effect 7 , so that the stain-preventing mat is less likely to stick or tear when peeled off from the top plate.
The invention described in claim 8 achieves the above-mentioned effect 8 , so that the stain-preventing mat is less likely to stick or tear when peeled off from the top plate.
The invention of claim 9 provides the above-mentioned effect 9 , so that the stain-preventing mat is less likely to stick or tear when peeled off from the top plate.

1 is an enlarged perspective view showing the general shape of a stain prevention mat for an induction cooker according to a first embodiment of the present invention; 2 is an enlarged cross-sectional view taken along the line II-II shown in FIG. 1. 1 is a plan view showing the external appearance of a conventional stain-preventing mat for an electromagnetic cooker when used in a general cooking heating device incorporating an electromagnetic cooker. 4 is a diagram corresponding to the line IV-IV shown in FIG. 3, and is a cross-sectional view schematically showing the operating principle of an induction cooker and an enlarged cross-sectional view of a conventional stain-preventing mat for an induction cooker.

Figure 1 is an enlarged perspective view showing the general shape of a stain-prevention mat for an induction cooktop according to a first embodiment of the present invention, and Figure 2 is an enlarged cross-sectional view taken along line II-II shown in Figure 1.

Referring to these figures, the stain-preventing mat 1 is for use with an induction cooktop, sandwiched between the top plate of the cooktop and the bottom of a pot heated by the induction cooktop. It consists of a circular cutout of a heat-resistant sheet 2 that is permeable to magnetic lines. The sheet 2 comprises a sheet-like woven fabric 3 made of a plain-woven glass fiber that is permeable to magnetic lines and heat-resistant, and has a maximum tear strength of 5.0 kN/m to 240 kN/m. Coating materials 4a and 4b are formed on both sides of the woven fabric 3 and are made of water-impermeable, heat-resistant silicone. In this specification, "silicone" refers to silicone resin, silicone rubber, and both. This configuration provides a predetermined tear strength, making the stain-preventing mat 1 less likely to stick or tear when peeled from the top plate. Furthermore, a maximum tear strength of 15.0 kN/m or more is more preferable, since it reduces the likelihood of even slight adhesion of the stain-preventing mat 1. From the standpoint of adhesion, there is no particular upper limit to the maximum tear strength of the sheet body 2. However, the tear strength of the sheet body 2 varies depending on the thickness and fiber density of the glass fiber-containing woven fabric 3 that constitutes the sheet body 2, which affect the response of the temperature sensor that detects the temperature of the top plate. Therefore, setting the tear strength of the sheet body 2 to 240 kN/m or less, more preferably 210 kN/m or less, can also reduce the impact on the response of the temperature sensor. Furthermore, if the tear strength of the sheet body 2 is too high, the sheet body 2 may be difficult to handle and process during the manufacture of the stain-preventing mat 1. Furthermore, having a tear strength higher than necessary is undesirable because it may waste resources and be environmentally friendly. The outer peripheral edge of the sheet body 2 may be bordered around the entire periphery with bias tape or the like that creates a U-shaped cross section.

When the sheet-like material is a woven fabric 3 formed by weaving glass fibers, the stain-preventing mat 1 has the required heat resistance and strength while also being flexible, resulting in a stain-preventing mat 1 with the required strength and excellent heat resistance, impact resistance, and flexibility. Furthermore, since commonly available, general-purpose glass fibers can be used, manufacturing costs can also be reduced. Furthermore, when the coating materials 4a and 4b are made of silicone, the surface of the stain-preventing mat 1 is non-slip, heat-resistant, and impermeable, resulting in a stain-preventing mat 1 that is easy to use.

To go into more detail about the structure and effects of the stain-prevention mat 1, the stain-prevention mat 1 uses woven fabric 3 as its core material, which gives it cushioning properties. Furthermore, the impermeable coating materials 4a and 4b fill the weaves of the woven fabric 3, preventing dirt from reaching the interior of the woven fabric 3, making the entire stain-prevention mat 1 impermeable.

When the stain-prevention mat 1 configured in this manner is placed on the top plate 17 of the induction cooker 13a or 13b in place of the stain-prevention mat 51 shown in Figures 3 and 4 and a pot 19 is placed on top of it, the stain-prevention mat 1 prevents dirt adhering to the bottom of the pot 19 and food splashes from adhering directly to the top plate 17, just like the stain-prevention mat 51.

Furthermore, due to the stain prevention mat 1's own cushioning properties, there is no risk of damaging the top plate 17 or pot 19 during use, and there is no risk of the stain prevention mat 1 itself breaking, making it easy to handle. Furthermore, the woven fabric 3 made from glass fiber is a material that not only has excellent cushioning properties, but also has excellent heat and impact resistance, further improving reliability during use. Furthermore, because it is an inexpensive material, the stain prevention mat 1 is cost-effective (economically efficient).

Furthermore, the coating materials 4a and 4b are heat-resistant, so there is no risk of them melting during cooking, and they provide anti-slip properties to the bottom of the pot 19 and the top plate 17, making them even easier to use. Furthermore, the coating materials 4a and 4b are water-repellent, so not only is there no risk of liquid dirt penetrating into the woven fabric 3, but they can also be easily washed with water, allowing for more hygienic use of the stain-prevention mat 1.

It is preferable that the thickness of the sheet body 2 be 0.74 mm or less. This configuration reduces the impact on the temperature sensor 18 that detects the temperature of the top plate 17, thereby reducing the risk of malfunctions when using the induction cooker 13a or 13b.

The sheet-like material, woven fabric 3, has a thickness of 0.02 mm to 0.42 mm, and the coating weight (weight after drying) of each of the surface coating material 4a and the back coating material 4b is preferably 5 g/ ^m² to 520 g/ ^m² , more preferably 10 g/ ^m² or more, and even more preferably 20 g/ ^m² to 150 g/ ^m² . This configuration provides both cushioning and a predetermined tear strength, while minimizing the impact on the temperature sensor 18 that detects the temperature of the top plate 17. This reduces damage to the top plate 17 and pots 19, prevents adhesion or tearing of the stain-prevention mat 1, and minimizes interference with the proper operation of the temperature sensor 18. Furthermore, particularly when the coating weight is 150 g/ ^m² or less, waste of the coating materials 4a and 4b is reduced, resulting in a stain-prevention mat 1 that is cost- and resource-efficient.

Furthermore, the total coating amount (weight after drying) of the coating materials 4a and 4b of the sheet body 2 is preferably 20 g/ ^m2 or more and 570 g/ ^m2 or less, and more preferably 30 g/ ^m2 or more and 300 g/ ^m2 or less. This configuration further reduces the effect on the temperature sensor 18 that detects the temperature of the top plate 17, and does not interfere with the proper operation of the temperature sensor 18.

Furthermore, the coating thickness (thickness after drying) of the coating material on both the front and back surfaces is preferably 2 μm to 300 μm, and more preferably 10 μm to 90 μm. This configuration provides both cushioning properties and a predetermined tear strength, while minimizing the impact on the temperature sensor 18 that detects the temperature of the top plate 17. This makes it less likely to damage the top plate 17 or pot 19, prevents the stain-prevention mat 1 from sticking or tearing, and is less likely to interfere with the proper operation of the temperature sensor 18. Furthermore, since waste of the coating materials 4a and 4b is avoided, the stain-prevention mat 1 is cost- and resource-efficient.

Furthermore, the total coating thickness (thickness after drying) of the coating material on the sheet body is preferably 4 μm or more and 330 μm or less, more preferably 10 μm or more, and even more preferably 15 μm or more and 180 μm or less. This configuration further reduces the impact on the temperature sensor 18 that detects the temperature of the top plate 17, so that the proper operation of the temperature sensor 18 is not hindered.

In the first embodiment described above, the stain-prevention mat was made of woven fabric and a coating material formed on both sides of the woven fabric, but it may also be made of silicone only.

In addition, in the first embodiment described above, the sheet-like material was a plain-woven fabric of glass fiber, but it may also contain glass fiber in part, or may be made of other fibers or materials that are permeable to magnetic lines and heat-resistant. For example, it may be a nonwoven fabric made of glass fiber, a woven or nonwoven fabric made of carbon fiber or ceramic fiber, or paper.

Furthermore, in the first embodiment described above, the coating material was formed on the entire surface of both sides of the woven fabric, but it may be formed only on a portion of the surface. It may also be formed on only one side, or it may not be present at all.

Furthermore, in the first embodiment described above, the coating material is made of silicone, but it may also contain silicone in part, or may be made of other non-permeable materials. It is preferable for the coating material to be permeable to magnetic lines of force, but even if it is non-permeable above a certain thickness, it can also be used as long as it can maintain permeability when the thickness is reduced below the certain thickness.

Furthermore, while in the first embodiment described above the stain-prevention mat is circular, it may be other shapes such as rectangular or donut-shaped. If an opening is formed in the center, as in the donut-shaped case, it can also be used as a stain-prevention mat for a gas stove by placing it under the trivet of a gas stove other than an induction cooker. Therefore, in the present invention, even if it can be used as a stain-prevention mat for a gas stove, it is considered to be within the scope of the present invention as long as it can also be used as a stain-prevention mat for an induction cooker.

Furthermore, in the first embodiment described above, it was preferable that the thickness of the sheet body, the thickness of the sheet-like material, the coating amount on each of the front and back sides of the coating material, and the total coating amount on the front and back sides were all set within specific ranges, but they may be set outside the specific ranges as long as the maximum tear strength of the sheet body is 5.0 kN/m or more and 240 kN/m or less.

Experiments were conducted to evaluate the degree to which the tear strength of the above-mentioned stain prevention mat affects the adhesion phenomenon, and the degree to which the thickness of the sheet body affects the temperature sensor.

For the experiment, stain-prevention mat samples were prepared with different glass fiber types, amounts of coating material (silicone) on the front and back (weight after drying), tear strength, sheet thickness, and thickness of coating material (silicone) on the front and back, as shown in Table 1. Table 1 also shows the results of the experiment (Evaluation 1 and Evaluation 2), details of which will be described later. The information for each glass fiber shown in Table 1 is as shown in Table 2 below.

The tear strength in Table 1 was measured using a test method conforming to JIS K6252:2015 (trouser type) constant-rate elongation type, with a tensile speed of 10 cm/min, and the tear strength refers to the maximum value (maximum strength). The sheet thickness is the arithmetic average of the thicknesses measured at three locations near the tear point of the test piece using a dial thickness gauge according to the method specified in JIS K 6250-10 (dimensional measurement method). The thicknesses of the coating material on the front and back surfaces (coating thicknesses) are the arithmetic average of the thicknesses of the coating material measured at 10 locations at 200 μm intervals in a direction perpendicular to the thickness of the coating material (i.e., a direction parallel to the glass fiber woven fabric used as the sheet material) after embedding the sheet in epoxy resin so that the cross section of the sheet was the observation surface and observing the polished surface with a scanning electron microscope (SEM). The name of the scanning electron microscope used for observing the cross section of the sheet body with the scanning electron microscope and the measurement conditions are as follows: As a pretreatment for the observation with the scanning electron microscope, the sheet body to be observed was embedded in epoxy resin, mechanically polished, and then carbon vapor deposited.
Device name: Hitachi High-Technologies Corporation scanning electron microscope (model number: S-3700N), measurement conditions: measurement magnification 150x, acceleration voltage 5 kV, vacuum degree 10 Pa, backscattered electron image acquisition. Furthermore, these images obtained by the scanning electron microscope were analyzed using image analysis software (Mitani Corporation's WinRoof2018) under the condition of measuring the distance between two points.

To further explain the tear strength measurement, first, each sample was prepared as a trouser-shaped test specimen (each rectangular sample had a slit cut from the center of one short edge parallel to the longitudinal direction). Next, the maximum tear force (maximum strength) required for each test specimen was measured, starting from the slit and with the tear direction at a 45° angle to the crease in the glass fiber. Note that the tear strength in JIS K6252:2015 (trouser-shaped) is defined as the median tear force required from the slit, determined in accordance with JIS K6274, divided by the thickness of the test specimen. However, in the above samples, which primarily consist of glass fiber, the glass fiber would break apart as tearing began, causing a rapid drop in the measured value and preventing accurate measurement results. Therefore, in this experiment, the tear strength value was determined by dividing the maximum force required to tear (maximum strength) by the thickness of the test specimen, rather than the median force required to tear.

Next, the influence of each sample on the sticking phenomenon (Evaluation 1) was evaluated.
(1) Specifications of the equipment used in the measurement of Evaluation 1 Muffle furnace: electric furnace (manufactured by Yamato Scientific Co., Ltd.: FO510)
Crystallized glass: Ultra heat-resistant crystallized glass: 3 mm thick (manufactured by Nippon Electric Glass Co., Ltd.: Neoceram N-0)
(2) Measurement details of evaluation 1 First, a specimen of each sample is placed on the crystallized glass and heated in a muffle furnace at 300 ° C for 16 hours. After heating is completed, the specimen is cooled to room temperature and then peeled off from the crystallized glass. When peeling off, the specimen is evaluated as ⊚ if it peels off cleanly, ◯ if some silicone of the specimen remains on the crystallized glass but can be easily removed by rubbing with fingers, and × if silicone and glass fiber of the specimen remain on the crystallized glass (including when the specimen is torn).
(3) Measurement Results of Evaluation 1 The following points were revealed from the measurement results of Evaluation 1.

First, in Examples 1 to 3, the specimen peeled cleanly in Examples 1 and 2, whereas in Example 3, which had the lowest tear strength, some of the silicone from the specimen remained on the crystallized glass, although it was easily removable. Furthermore, in Comparative Example 1, which had the same glass fibers in the woven fabric and the same amount of coating material on the front surface as Example 3, but with a lower amount of coating material on the back surface and lower tear strength than Example 3, the silicone and glass fibers from the specimen remained on the crystallized glass, resulting in the specimen tearing. Furthermore, in Example 4 and Comparative Example 2, which had higher tear strength than Examples 1 to 3, the specimen peeled cleanly. Therefore, it can be said that the presence and extent of the sticking phenomenon depend on the tear strength of the sheet body.

Specifically, if the maximum tear strength of the sheet body is 5.0 kN/m or more, the mat has the specified tear strength, making it less likely to stick or tear when peeled off from the top plate.

In addition, for a sheet body having a maximum tear strength of 5.0 kN/m or more, in order for the stain-prevention mat to have both cushioning properties and a predetermined tear strength, it is preferable that the thickness of the woven fabric material be 0.02 mm or more, and that the coating material have a coating amount of 5 g/ ^m2 or more on each of the front and back surfaces, with the total coating amount being 20 g/ ^m2 or more.

Among the above samples, the sample with the largest sheet thickness (Comparative Example 2) had the highest tear strength, but increasing the sheet thickness increases the insulating effect of the stain-prevention mat. Furthermore, if the insulating effect of the sheet is too high, it becomes difficult for the temperature of the pot to be transmitted to the temperature sensor. Therefore, even if a stain-prevention mat has high tear strength and is less likely to stick, it can be said to be unsuitable for use if its insulating effect is too high and it interferes with the proper operation of the temperature sensor.

Therefore, the influence of each sample on an induction cooker when used (evaluation 2) was measured.
(4) Specifications of the equipment used in the measurements of Evaluation 2: Induction cooker: Cooking heater (Mitsubishi Electric: CS-G3205BDS)
Pot: Dedicated tempura pot: 22cm diameter (manufactured by Urushiyama Metal Industry: CS-100667)
Oil: Nissin salad oil (Nissin Oillio Group)
Oil temperature measuring device: Infrared radiation thermometer (manufactured by Sato Keiki: SK-8700II)
(5) Measurement details for evaluation 2: Each sample was placed between the pan and the top plate, and 200 cc of salad oil was poured into the pan and heated using the "deep-frying function." The "deep-frying function" refers to the function in which the temperature sensor detects the heat of the heated pan via the top plate, and adjusts the amount of heat based on this detected temperature to maintain the oil temperature at approximately 200°C.

Furthermore, the induction cooker used requires a minimum of 500cc of oil to be used safely. Therefore, the 200cc of oil used in this case was not an appropriate amount.

If the oil temperature did not exceed 300°C and the induction cooker automatically finished preheating (stopped heating), it was evaluated as ◯, and if it exceeded 300°C, it was evaluated as ×.
(6) Measurement Results of Evaluation 2 The following points were revealed from the measurement results of Evaluation 2.

In Examples 1 to 4 and Comparative Example 1, the induction cooker automatically stopped heating before the oil temperature exceeded 300°C, whereas in Comparative Example 2, which had the largest values for sheet thickness and coating thickness, the induction cooker did not automatically stop heating and the oil temperature exceeded 300°C. This means that Comparative Example 2 does not provide temperature control for the frying function, posing a safety issue. Therefore, it can be said that the thickness of the sheet and the coating thickness of the coating affect the proper operation of the temperature sensor on an induction cooker. Furthermore, since the thickness of the sheet is determined by the thickness of the woven fabric (sheet-like material), the coating amount and coating thickness on the front and back of the coating material, and the total coating amount and total coating thickness on both sides, it can be said that these also affect the proper operation of the temperature sensor.

Specifically, if the sheet thickness is 0.74 mm or less, it will have less of an effect on the temperature sensor that detects the temperature of the top plate, reducing the risk of malfunctions when using an induction cooktop.

Furthermore, if the total coating thickness of the coating material on the front and back surfaces is 326.2 μm or less, the impact on the temperature sensor that detects the temperature of the top plate will be further reduced, and the temperature sensor will not be hindered from operating properly.

In addition, for a sheet body having a thickness of 0.74 mm or less, in order to provide a predetermined tear strength while minimizing the impact on the temperature sensor, it is preferable that the maximum tear strength be 5.0 kN/m or more and 240 kN/m or less. Furthermore, if the thickness of the woven fabric material is 0.42 mm or less and the coating amount of the coating material is 520 g/ ^m2 or less on each of the front and back surfaces, it is more preferable because it combines cushioning properties and a predetermined tear strength while minimizing the impact on the temperature sensor detecting the temperature of the top plate. Furthermore, if the total coating amount of the coating material is 570 g/ ^m2 or less, it is even more preferable because it further minimizes the impact on the temperature sensor detecting the temperature of the top plate.

From the above, it can be said that the tear strength of a stain-prevention mat has a significant impact on the adhesion phenomenon of the stain-prevention mat, while the thickness of the stain-prevention mat sheet, the thickness of the sheet material, the amount and thickness of the coating on the front and back of the coating material, and the total amount and thickness of the coating on both sides all have a significant impact on the operating state of an induction cooker, and it is only with the appropriate selection of these factors that the existence of a stain-prevention mat becomes meaningful.

That is, in the stain-preventing mat, the maximum tear strength of the sheet body is preferably 5.0 kN/m or more and 240 kN/m or less, and in addition, the thickness of the sheet body is 0.74 mm or less, the thickness of the sheet-like material of the sheet body is 0.02 mm or more and 0.42 mm or less, the coating material has a coating amount of 5 g/ ^m2 or more and 520 g/ ^m2 or less on each of the front and back sides, with a total coating amount of 20 g/ ^m2 or more and 570 g/ ^m2 or less, and the coating thickness of each of the front and back sides is 2 μm or more and 300 μm or less, with a total coating thickness of 4 μm or more and 330 μm or less. Furthermore, if the maximum tear strength of the sheet body is 15.0 kN/m or more, the sticking phenomenon itself is less likely to occur, making it an even more preferable stain-preventing mat.

REFERENCE SIGNS LIST 1...stain prevention mat 2...sheet body 3...woven fabric 4a, 4b...coating material 13a, 13b...electromagnetic cooker 17...top plate 19...pot Note that the same symbols in each drawing indicate the same or corresponding parts.

Claims (9)

A stain-preventing mat for an induction cooker is sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker,
It is made of a heat-resistant sheet body that is permeable to magnetic lines of force,
The sheet body has a maximum tear strength of 5.0 kN/m or more and 200.5 kN/m or less,
The sheet body is a stain-preventing mat for an induction cooker, which is made of glass fiber and silicone formed on both sides of the glass fiber . The stain-preventing mat for induction cookers according to claim 1, wherein the thickness of the sheet body is 0.74 mm or less. The sheet body is
a sheet-like material made of heat-resistant fibers;
and a coating material formed on both sides of the material and having water impermeability.
The material has a thickness of 0.04 mm or more and 0.42 mm or less,
The coating material has a coating amount of 5 g/m ² or more and 50 g/m ² or less on the surface ,
3. The stain-preventing mat for an induction cooker according to claim 1 , wherein the coating material has a coating weight of 15 g/m ^{<2 >} or more and 520 g/m ^{<2 >} or less on the back surface. The sheet body is
The stain-preventing mat for an induction cooker according to claim 3, wherein the total coating amount of the coating material is 20 g/m ² or more and 570 g/m ² or less. The sheet body is
a sheet-like material made of heat-resistant fibers;
and a coating material formed on both sides of the material and having water impermeability.
The material has a thickness of 0.04 mm or more and 0.42 mm or less,
The coating material has a coating thickness of 2.9 μm or more and 28.6 μm or less on the surface ,
3. The stain-preventing mat for an induction cooker according to claim 1 , wherein the coating material has a coating thickness of 8.6 μm or more and 297.6 μm or less on the back surface . The sheet body is
The stain-preventing mat for an induction cooker according to claim 5, wherein the total coating thickness of the coating material is 11.5 μm or more and 326.2 μm or less . A stain-preventing mat for an induction cooker is sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker,
It is made of a heat-resistant sheet body that is permeable to magnetic lines of force,
The sheet body has a maximum tear strength of 15.0 kN/m or more and 200.5 kN/m or less,
The sheet body includes a sheet-like material made of heat-resistant fibers,
and a coating material formed on both sides of the material and having water impermeability.
the coating material contains silicone,
This stain-preventing mat for an electromagnetic cooker prevents the silicone of the sheet body from remaining on the top plate of the electromagnetic cooker during use, resulting in no sticking phenomenon. A stain-preventing mat for an induction cooker is sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker,
It is made of a heat-resistant sheet body that is permeable to magnetic lines of force,
The sheet body has a maximum tear strength of 5.0 kN/m or more and 200.5 N/m or less,
The thickness of the sheet body is 0.74 mm or less,
The sheet body includes a sheet-like material made of heat-resistant fibers,
and a coating material formed on both sides of the material and having water impermeability.
The material includes glass fiber,
the coating material contains silicone,
The material has a thickness of 0.04 mm or more and 0.42 mm or less. A stain-preventing mat for an induction cooker is sandwiched between the top plate of the induction cooker and the bottom surface of a pot heated by the induction cooker,
It is made of a heat-resistant sheet body that is permeable to magnetic lines of force,
The sheet body has a maximum tear strength of 5.0 kN/m or more and 200.5 kN/m or less,
The sheet body includes a sheet-like material made of heat-resistant fibers,
and a coating material formed on both sides of the material and having water impermeability.
The material includes glass fiber,
the coating material contains silicone,
The thickness of the sheet body is 0.74 mm or less,
The material has a thickness of 0.04 mm or more and 0.42 mm or less,
The coating material has a coating thickness (thickness after drying) of 2.9 μm or more and 28.6 μm or less on the surface ,
The stain-preventing mat for an induction cooker , wherein the coating material has a coating thickness (thickness after drying) on the back surface of 8.6 μm or more and 297.6 μm or less .