JP6370858B2 - Heat conduction paste for interposing between heating device and object to be heated and heat conduction method using the heat conduction paste - Google Patents

Description

  The present invention relates to a heat conductive paste that is interposed between a heating device (heat generating device) such as a heater and an object to be heated and efficiently conducts heat generated from the heating device to the object to be heated, and heat conduction using the heat conductive paste. Regarding the method.

  In industrial heaters, such as cartridge heaters, seed heaters, band heaters, plate heaters, etc., they are inserted into metal parts (objects to be heated) such as injection molding machines and sealing machines, fitted, and fixed. To heat the part.

  If these heaters have gaps or voids (air layers, spaces) between their heating surface and the heated surface of the object to be heated, not only will there be a loss in heat conduction to the object to be heated, but heat will also be generated inside the heater. As a result, the heater may be damaged, for example, the nichrome wire as the resistance heating element may be cut off.

  In particular, cartridge heaters and sheathed heaters that have a cylindrical shape and are heated by being inserted into a round hole in the object to be heated must have an outer diameter that is smaller than the inner diameter of the round hole. A gap is likely to occur between the surface (heating surface) and the inner circumferential surface of the round hole (surface to be heated).

  In addition, the heater shape is a cylindrical shape, and the band heater has a structure in which the inner diameter of the heater must be larger than the outer diameter of the object to be heated. In other words, a gap is likely to occur between the inner peripheral surface of the heater (heating surface) and the outer peripheral surface of the object to be heated (heated surface).

  In addition, even if surface treatment such as polishing is performed on the heated surface or the heated surface, slight irregularities remain, and gaps or voids are generated between the heated surface and the heated surface due to the irregularities.

  Therefore, the following Patent Document 1 has a technical idea that gaps and voids between a heated surface and a heated surface are filled with a paste containing a material having high thermal conductivity (thermal conductive paste) to promote efficient heat conduction. It is disclosed.

Japanese Patent No. 5223226

  However, the heat conductive paste of Patent Document 1 uses “curable resin” as a main agent, and therefore presupposes that it is hardened like an adhesive after drying.

  Therefore, for example, when the heat conductive paste of Patent Document 1 is applied to a heater that is fitted to an object to be heated, the heater is adhered to the object to be heated after drying and curing, and it becomes difficult to remove. Heaters, especially industrial heaters, are often replaced and used repeatedly and must be easily removed.

  The present invention provides a heat conduction paste and a heat conduction method capable of realizing effective heat conduction and greatly extending the life of the heater, and considering replacement and repeated use of the heater.

  In short, the thermal conductive paste according to the present invention is composed of silicon carbide or boron nitride as a thermal conductive agent, smectite or bentonite as a precipitation inhibitor, and water as the main ingredients. An aqueous heat conductive paste containing 30 to 60 parts by mass of the heat conductive agent, 1 to 4 parts by mass of the suspending agent and 36 to 69 parts by mass of water with respect to a total of 100 parts by mass of the agent and water. Yes, it can penetrate into the minute gaps and voids between the heated surface (heat generating surface) and the heated surface evenly and densely to promote efficient heat conduction and harden enough to exhibit an adhesive effect even when dried Thus, the heating device such as a heater can be easily removed from the object to be heated after use.

In addition, by adding 30 to 100 parts by mass of a graphene 5% dispersion to the total 100 parts by mass of the thermal conductive agent, the suspending agent and water, the viscosity is reduced and the thermal conductive paste is applied. The smoothness of the finished surface is improved. Preferably, water is used as the solvent of the graphene 5% dispersion.

  Further, in the heat conduction method according to the present invention, the heat conductive paste according to claim 1 is interposed between the heating surface of the heater and the heated surface of the object to be heated in an undried state, that is, with a moisture-rich content. Accordingly, the heating surface and the heated surface can be brought into close contact with each other while fluidity is ensured.

  According to the heat conductive paste according to the present invention, high efficiency heat conduction can be realized by effectively filling fine gaps and voids between the heating surface and the surface to be heated. On the other hand, after drying (after using the heater) The surface to be heated can be easily separated. Further, since it is aqueous, it can be easily removed by washing with water or wiping with a wet cloth.

  In addition, according to the heat conduction method of the present invention, the heated surface and the heated surface can be brought into close contact with moisture, and the thermally conductive paste can be interposed between the heated surface and the heated surface while maintaining fluidity. . Therefore, it is possible to effectively fill the gaps and gaps between the heating surface and the heated surface and realize efficient heat conduction.

The perspective view of a cartridge heater. (A) is a perspective view explaining the insertion of the cartridge heater into the round hole of the object to be heated, (B) is a longitudinal sectional view showing a state in which the cartridge heater is inserted into the object to be heated. Sectional drawing which expands and shows the heating surface of a heater, and the to-be-heated surface of a to-be-heated material. The expanded cross-sectional view which shows the state which inserted the cartridge heater or the sheathed heater in the to-be-heated material. (A) is a perspective view which shows the state which inserted the sheathed heater in the to-be-heated material, (B) is the longitudinal cross-sectional view. (A) is a perspective view which shows the state which fitted the band heater to the outer peripheral surface of to-be-heated material, (B) is the longitudinal cross-sectional view. The expanded cross-sectional view which shows the state which fitted the band heater to the to-be-heated material. (A) is a perspective view which shows the state which fixed the plate heater to the to-be-heated object, (B) is the longitudinal cross-sectional view.

  Hereinafter, the heat conductive paste according to the present invention will be described in detail, and a heat conductive method using the heat conductive paste will be described with reference to FIGS. 1 to 8.

<Thermal conductive paste>
The heat conductive paste according to the present invention is an aqueous paste comprising a heat conductive agent, which is a powder having heat conductivity, a suspending agent for preventing precipitation of the heat conductive agent, and water as a solvent. It is a heat conductive paste.

  As the thermal conductive agent, silicon carbide (SiC) or boron nitride (BN) powder is used. Of these, silicon carbide is more preferable because it is excellent in heat resistance and hardness in addition to thermal conductivity.

  As the precipitation inhibitor, smectite or bentonite is used. These suspending agents absorb water and swell, form a highly viscous sol, and effectively prevent precipitation of the heat conducting agent.

  As a blending example, 30 to 60 parts by mass of the thermal conductive agent is included for 100 parts by mass of the total of 100 parts by mass of silicon carbide or boron nitride as the thermal conductive agent, smectite or bentonite as the precipitation inhibitor, and 1 precipitation inhibitor. It is set as the mixing | blending which contains 36-69 mass parts of water while containing ~ 4 mass parts. A heat conductive agent can be disperse | distributed appropriately by mix | blending each agent in the range shown to this compounding example.

  Further, in the heat conductive paste according to the present invention, 30 to 100 parts by mass of graphene 5% dispersion or graphite 5% dispersion with respect to a total of 100 parts by mass of the heat conductive agent, the precipitation inhibitor and water. Liquid can be added. As a result, the viscosity is reduced and the lubricity of the surface on which the heat conductive paste is applied is improved. Preferably, water is used as a solvent for the graphene 5% dispersion and the graphite 5% dispersion.

  When producing the heat conductive paste according to the present invention mainly composed of the above-mentioned heat conductive agent, suspending agent and water, first the suspending agent and water are stirred and dissolved to form a paste, and then the heat conductive agent is mixed. Stir to disperse the thermal conductive agent. The viscosity is adjusted to about 23 to 25 Pa · s (25 ° C.).

  Moreover, when adding a graphene 5% dispersion and the said graphite 5% dispersion, the said dispersion is added and further stirred, and a viscosity is adjusted to about 10-11 Pa.s (25 degreeC).

  According to the heat conductive paste according to the present invention, it is possible to effectively fill a minute gap or gap between the heated surface and the heated surface to realize high-efficiency heat conduction, while easily using the heated surface and the heated surface after use. Can be separated.

  In addition, since it is water-based, it can be used safely and safely, and can be easily removed by simply rinsing with water or wiping with a wet cloth after drying.

<Thermal conduction method>
First, the relationship between a cartridge heater, a sheathed heater, a band heater and a plate heater (also called flat heater or space heater), which are typical industrial heaters, and an object to be heated will be described.

  1 and 2 show the relationship between the cartridge heater 1 and a heated object 2 such as a small mold, and similarly, FIG. 5 shows the relationship between the sheathed heater 1 and the heated object 2 such as a small mold. 6 shows the relationship between the band heater 1 and the heated object 2 having a cylindrical or cylindrical shape such as a pipe or nozzle, and FIG. 7 shows the relationship between the plate heater and the heated object 2 having a planar heated surface 2a. Yes.

  The cartridge heater 1 has a cylindrical shape as a whole as shown in FIG. 1, and is used by being inserted into a round hole 5 of an object to be heated 2 as shown in FIG. Also, the sheathed heater 1 has a cylindrical shape as shown in FIG. 5 and is inserted into the round hole 5 of the article 2 to be heated. Therefore, the cartridge heater and the sheathed heater have a structure in which the outer diameter of the heater 1 must be smaller than the inner diameter of the round hole 5, and as shown in FIG. 4, the outer peripheral surface of the heater, that is, the heating surface 1a and the round hole A gap 3A tends to occur between the peripheral surfaces, that is, the heated surface 2a. Moreover, as shown in FIG. 3, the space | gap 3B may generate | occur | produce by the uneven | corrugated shape of the heating surface 1a or / and the to-be-heated surface 2a. In the present invention, as described later, the gap 3 </ b> A and the gap 3 </ b> B can be filled with the heat conductive paste 4 to perform effective heat conduction.

  Moreover, as shown in FIG. 6, the band heater 1 has a cylindrical heater shape, and is used by being fitted to the outer peripheral surface of a heated object 2 having a columnar shape or a cylindrical shape. Therefore, structurally, the inner diameter of the heater 1 must be larger than the outer diameter of the article 2 to be heated, and as shown in FIG. A gap 3A is likely to occur between the heating surfaces 2a. Moreover, as shown in FIG. 3, the space | gap 3B may generate | occur | produce by the uneven | corrugated shape of the heating surface 1a or / and the to-be-heated surface 2a. In the present invention, as described later, the gap 3A and the gap 3B can be effectively filled with the heat conductive paste 4, and heat can be conducted from the heating surface 1a to the heated surface 2a without loss.

  Further, as shown in FIG. 8, the plate heater 1 has a flat heating surface 1a, and heats the same heated surface 2a. Therefore, it is a surface contact between flat surfaces, and in this case as well, if there is unevenness on at least one surface, there is a possibility that a void 3B will be formed, as shown in FIG. Heat conduction can be performed.

  The heat conduction method according to the present invention comprises the above-described heat conduction paste 4 (silicon carbide or boron nitride as a heat conduction agent, smectite or bentonite as a precipitation inhibitor, and water as the main ingredients, and the heat conduction described above. An aqueous solution containing 30 to 60 parts by mass of the thermal conductive agent, 1 to 4 parts by mass of the precipitation inhibitor and 36 to 69 parts by mass of the water with respect to a total of 100 parts by mass of the agent, the precipitation inhibitor and water. Heat conductive paste 4 or aqueous heat conductive paste 4) in which 30 to 100 parts by mass of graphene 5% dispersion or graphite 5% dispersion is added to heating surface 1a of heater 1 and heated surface 2a of object 2 to be heated It is characterized by interposing it in an undried state.

  Specifically, first, the undried aqueous heat conductive paste 4 is applied to the heating surface 1a and / or the heated surface 2a. The coating method may be a known coating method such as brush coating, roller coating, or spray coating.

  In particular, the aqueous heat conductive paste 4 to which the graphene 5% dispersion or the graphite 5% dispersion is added improves the lubricity of the coated surface (the heated surface 1a and / or the heated surface 2a) in an undried state. Therefore, when the heater 1 to be used is a cartridge heater or a sheathed heater, the object to be heated 2 can be smoothly inserted into the round hole 5.

  Moreover, according to the heat conduction method according to the present invention, the aqueous heat conductive paste 4 is interposed between the heating surface 1a and the surface to be heated 2a in an undried state, that is, in a state of being rich in moisture. Therefore, the heating surface 1a and the heated surface 2a can be brought into close contact with each other by the surface tension of moisture, and the heat conductive paste can be interposed between the heated surface 1a and the heated surface 2a while maintaining fluidity. Therefore, it is possible to effectively fill the gap 3A and the gap 3B between the heating surface 1a and the heated surface 2a and realize efficient heat conduction.

  On the other hand, since the aqueous heat conductive paste 4 according to the present invention does not harden to the extent that it exhibits an adhesive effect even when dried, the coating film can be easily broken after the heater 1 is used. Therefore, the heater 1 can be easily detached from the article 2 to be heated. In addition, the coating film remaining on the heater 1 or the object to be heated 2 can be easily removed by washing away with water or wiping with a wet cloth.

<Demonstration experiment>
Next, the experiment conducted in order to demonstrate the effect of the heat conductive paste and heat conductive method concerning this invention is demonstrated.

The heat conductive paste used was manufactured by the following composition.
≪Thermal conductive paste≫
Thermal conductive agent ... Silicon carbide powder 45 parts by mass Precipitation inhibitor ... Smectite 3 parts by mass Water 52 parts by mass
Total 100 parts by mass

The specifications and dimensions of the heater used and the materials and dimensions of the object to be heated are as follows.
≪Heater (cartridge heater) ≫
Working voltage 100V
Capacity 300W
Outer diameter 15mm (+0 ・ -0.1)
Total length 95mm
≪Subject to be heated (small mold) ≫
Material ... Iron Depth 95mm
Width 25mm
Height 35mm
Round hole: penetrates the center along the depth direction of the mold. Therefore, the total length is 95mm
Round hole inner diameter 15mm (+0 ・ -0)

  Prepare a heater that does not apply thermal conductive paste to the outer peripheral surface and a heater that applies thermal conductive paste to the outer peripheral surface, insert each into a small mold (object to be heated), energize each heater, The surface temperature of the mold and the internal temperature of the heater were measured in time series with a known thermocouple. The room temperature is 23 ° C.

  The results are as shown in Table 1 below, and after 15 minutes of energization, the heater coated with the heat conductive paste has a lower internal temperature than the heater without coating, but the small mold as the object to be heated It can be seen that the surface temperature is higher than the surface temperature of the small mold heated by the heater without coating.

  The above results show that in a heater coated with a heat conductive paste, the heat conductive paste is interposed between the heated surface and the heated surface, and the heat generated from the heated surface is effectively conducted to the heated surface. It is none other than proof.

  In addition, at the heater internal temperature, after 15 minutes of energization, the material with the heat conductive paste applied was actually 63 ° C. lower than the one without the application, which is the “Arrhenius 10 ° C. double rule” (the temperature of the operating environment). If it is applied to the rule that the life will be doubled when the temperature drops by 10 ° C), the heater used by applying the thermal paste will last about 64 (2 6) times longer than the heater used without applying it. Will be.

DESCRIPTION OF SYMBOLS 1 ... Heater, 1a ... Heating surface 2 ... To-be-heated object, 2a ... Heated surface 3A ... Crevice, 3B ... Air gap 4 ... Thermal conductive paste 5 ... Round hole

Claims (3)

Silicon carbide or boron nitride as a heat conductive agent, smectite or bentonite as a precipitation inhibitor, and water are blended as main components, and the total amount is 100 parts by mass for the heat conductive agent, the precipitation inhibitor and water. the thermal interface material includes 30 to 60 parts by mass, seen from 36 to 69 parts by mass including the water with containing 1 to 4 parts by mass of the suspending agent, further the heat conducting agent, suspending agent and total 100 parts by weight of water On the other hand, an aqueous heat conductive paste for interposition between a heating apparatus and an object to be heated , wherein 30 to 100 parts by mass of graphene 5% dispersion is added . The graphene 5% dispersion of the solvent-mediated Aqueous heat conduction paste to between the heating device and the object to be heated according to claim 1, wherein the water.   A heat conduction method comprising interposing the heat conductive paste according to claim 1 between the heating surface of the heater and the surface to be heated of the object to be heated in an undried state.