HEATING JACKET AND METHOD OF MAKING HEATING JACKET

This application incorporates by reference herein KR Application No. 10-2017-0038285, filed March 27, 2017.

Technical Field

[0001] This invention relates to a heating jacket used for maintaining a constant temperature of an object that is heated relative to its surroundings, such as a pipe or cylinder in which gases used for semiconductor production are stored, and more particularly to a heating jacket that uses graphite to provide for uniform and constant heat conduction functionality.

Background Art

[0002] In the semiconductor production process, liquefied gas, low-pressure gas or specialty gas is typically stored in a Y-shaped cylinder; in many cases, this gas must be kept at a constant temperature during supply. [0003] Therefore, the installation of a heating jacket that surrounds such a cylinder is known in the art.

[0004] Heating jackets may have a structure as shown in Fig. 1 , comprising from top to bottom: an outer silicone layer 1 , a glass fiber layer 2, inner silicone layer 3, a heating wire (heater) 4, and a lower silicone layer 5, and may also have additional layers that are not shown between the layers shown, or in addition to the layers shown, including: one or more conductive layers and insulation layers.

[0005] In addition, hooks 6 for connecting the jacket holding belts may be installed on either side as shown, and hook mounting parts 6a are provided on both sides for fixing these hooks 6 in place. [0006] In addition, a temperature sensor 7 for sensing the temperature of the jacket and the cylinder, and an overheating prevention sensor 8 for preventing overheating of the jacket and the cylinder, are provided at positions that adjoin the surfaces of the jacket and cylinder.

[0007] In addition, a cable connecting part 9 is provided on one side to supply power to the heating wire (heater) 4 of the jacket and is electrically connected to the sensors 7 and 8 so as to sense and transmit the signals from these sensors.

[0008] Among prior art of this kind, in the "jacket heater" of Korean Registered Patent Gazette

No. 10-1575181 (2015.12.01), a structure is presented comprising a heat insulator between an inner cover and outer cover, a grounding (Cu Mesh), a glass fiber, and a heating wire.

l [0009] Patent Reference 1 is characterized by waterproofing, and preventing overheating by using glass fiber.

[0010] However, conventional heating jackets are wrapped around the cylinder but there are portions where they are not tightly adhered to each other and partial overheating may occur, and there is known to be a high risk of fire and short-circuiting of the heating wire.

[0011] In particular, unlike a heating jacket that encloses a pipe having a uniform cross section in a semiconductor production line, it is very important that the heating jacket is brought into close contact with the surface of the cylinder when there is a portion having an irregular cross- section such as a Y-shaped cylinder, and the above-described problems of thermal efficiency deterioration and fire risk, etc., become more pronounced.

[0012] In addition, existing heating jackets, by virtue of their structure, measure and control the temperature in a pointwise fashion; as a result of the occurrence of such defects with poor adhesion and temperature fluctuations occurring under on-site usage conditions, there also occur problems of local overheating or local degradation, as well as serious durability problems. Summary of Invention

[0013] In one aspect of this invention is provided heating jackets comprising an inner layer comprising silicone rubber material that contacts an object to be heated when said heating jacket is in use; a heater (having a heating element or wire for generating heat from electrical power and means to receive electrical power from an electrical power source to generate that heat); an intermediate layer comprising silicone rubber material; an outer layer comprising silicone rubber material; and a graphite layer made of a material comprising graphite located between said intermediate layer and said outer layer.

[0014] In another aspect of this invention is provided a heating jacket that may further comprise a plurality of holes formed on the surface of said graphite layer and/or formed through said graphite layer.

[0015] In another aspect of this invention, the heating jacket in addition to other aspects further comprises an adhesive layer in the holes, the adhesive layer fixes in place the graphite layer and the intermediate layer and may also fix in place: one or more of the outer layer, the inner layer and the heater in any combination of layers. (The heater may be considered a layer, herein.)

[0016] In another aspect of this invention, alone or with other aspects, the the plurality of holes is present in a uniform arrangement in the graphite layer and the plurality of holes are optionally circular and each hole may have a diameter from about 8 to about 12 mm and the distance between the centers of the holes in the plurality of holes may be from about 20 to about 30 mm. The plurality of holes in the graphite layer may have consistent sizing and spacing.

[0017] In another aspect of this invention, alone or with other aspects, the plurality of holes further comprise guide parts having rounded corners located at least on one surface of the graphite layer, which may be the surface of the graphite layer adjacent to said intermediate layer. In another aspect of this invention, alone or with other aspects, the plurality of holes may comprise guide parts having rounded corners on both surfaces of the graphite layer (although not shown herein).

[0018] In another aspect of this invention, alone or with other aspects, the plurality of holes further comprise guide parts, and said adhesive layer is further located in the guide parts 41a of the plurality of holes, said guide parts may be located on the surface of the graphite layer between the intermediate layer and the graphite layer.

[0019] In another aspect of this invention, alone or with other aspects, the adhesive layer comprises silicone rubber material. In another aspect of this invention, alone or with other aspects, the adhesive layer may comprise the intermediate layer after the application of heat and/or pressure to said intermediate layer and said graphite layer (and optionally to additional layers (the outer layer and/or the inner layer and/or the heater in a multilayer assembly). In another aspect of this invention, an adhesive layer is located (or formed by the application of heat and/or pressure) on both surfaces of the intermediate layer between the two or more layers in contact with the intermediate layer. (The layers in contact with the intermediate layer include one or more of the following layers in any combination: the graphite layer, the outer layer, the heater and the inner layer.) In another aspect, alone or with other aspects, the adhesive layer comprises silicone rubber material.

[0020] In another aspect, alone or with other aspects, the heating jacket is substantially free of any added adhesive material between said graphite layer, said intermediate layer and said outer layer. In another aspect, alone or with other aspects, the heating jacket is free of any added adhesive material between any of the layers located between said inner layer and said outer layer.

[0021] In another aspect of this invention is provided a method of making a heating jacket comprising the steps of: optionally forming a plurality of holes in or through a graphite layer; assembling said graphite layer having a plurality of holes therein or therethrough between an intermediate layer comprising silicone rubber material; and an outer layer comprising silicone rubber material to form a multilayer assembly; and applying heat and/or pressure to said multilayer assembly to soften said intermediate layer and cause said multilayer assembly to form a fused multilayer assembly. [0022] In another aspect of the invention, alone and with other aspects, the method comprises the additional step of: including in the multilayer assembly, prior to or after said applying heat and/or pressure step, a heater (having means to receive electrical power to generate heat) and an inner layer comprising silicone rubber material. In another aspect, the method of the invention will further comprise attaching a heater and an inner layer to said fused multilayer assembly. In the multilayer assembly the heater is located between the intermediate layer and the inner layer.

[0023] In another aspect of the invention, alone and with other aspects, the invention provides a method wherein said step of applying heat and/or pressure to said multilayer assembly to soften said intermediate layer forms an adhesive layer that fills the holes or at least partially fills the holes.

[0024] In another aspect of the invention, alone and with other aspects, the invention provides a method wherein said forming a plurality of holes step creates a uniform arrangement of holes in the graphite layer. In another aspect of the invention, alone and with other aspects, the invention provides a method wherein said forming a plurality of holes step creates a uniform arrangement of circular holes in the graphite layer, each hole having a diameter from about 8 to about 12 mm and the distance between the centers of the holes in the plurality of holes is from about 20 to about 30 mm.

[0025] In another aspect of the invention, alone and with other aspects, the invention provides a method wherein said forming a plurality of holes step further comprises forming guide parts in (each of) said plurality of holes.

[0026] In another aspect of the invention, alone and with other aspects, the invention provides a method wherein during said assembling step said guide parts in said holes in said graphite layer are located adjacent to said intermediate layer. [0027] In another aspect of the invention, alone and with other aspects, the invention provides a method free of any added adhesive material between either said graphite layer and said intermediate layer or between said graphite layer and said outer layer, or between said intermediate layer and said outer layer.

[0028] In another aspect of the invention, alone and with other aspects, the invention provides a method of making a heating jacket said method is free of any added adhesive material (that is, free of any steps of applying any added adhesive material) between any of said layers located between said inner layer and said outer layer, excluding adhesive materials that may be used to mount discrete contacts or wires to the heating jacket.

[0029] In another aspect of the invention, alone and with other aspects, said invention includes heating jackets made by any of the methods described herein. [0030] In another aspect of the invention alone or with other aspects is provided a heating jacket that when used contacts an object surrounds a cylinder in a semiconductor facility so as to keep the internal temperature of the cylinder constant, comprising: an inner layer 10 of silicone rubber material, making up the inner surface of the heating jacket surrounding said cylinder; a heater 20 that receives electrical power from outside and generates heat, installed on the outer surface of said inner layer 10; an intermediate layer 30 made of silicone rubber material and installed on the outer surface of said heater 20; a graphite 40 made of a material comprising graphite, and installed on the outer surface of said intermediate layer 30; and an outer layer 50 comprising a silicone rubber layer and installed on the outer surface of said graphite 40.

[0031] In another aspect of the invention alone or with other aspects is provided a heating jacket wherein an adhesive layer 42 is furnished that has been formed by (at least partially) filling the holes 41 with an adhesive, so that the adhesive layer 42 fixes in place the

intermediate layer 30 and outer layer 50 respectively on the inside and outside of the graphite 40.

[0032] The heating jacket of this invention resolve the problems that have arisen in the prior art as described above. The ground (e.g. Cu Mesh) formerly used for preventing the electric leakage is removed, the contact area is uniformly improved by installing graphite having not only electrical conductivity but also uniform thermal conductivity, and heat conductivity may be increased by utilizing the material properties of the graphite. Additionally, the heating jacket of this invention provides one or more of the following benefits: improved residual heat removal ability when the temperature is lowered from a high temperature to a low temperature, improved ability to maintain a constant temperature, increased durability, and/or better temperature control and and/or thereby fewer problems with overheating and improved safety. The invention keeps the portion of the heating jacket where the heater is located inside the jacket at a higher but uniform temperature as compared to the balance of the jacket where the heater is not located, which is beneficial to keeping the inside temperature of the object to be heated at a constant temperature, even if the object has a non-uniform shape, such as a Y- cylinder. Brief Description of Drawings

[0033] FIG 1 shows a heating jacket of the prior art.

[0034] FIG. 2 is a perspective view showing an embodiment of a heating jacket of this invention.

[0035] FIG. 3 is a plan view showing the overall shape of the graphite. [0036] FIG. 4 is a perspective view showing another embodiment of a heating jacket of this invention.

[0037] FIG. 5 is a cross-section showing the cross-sectional state of the heating jacket of this invention. [0038] FIG. 6 is a photograph comparing the infrared signature of a heating jacket using Cu mesh and a heating jacket according to this invention.

Detailed Description of the Invention

[0039] Hereinbelow, the heating jacket of this invention will be explained in detail with reference to the attached drawings. [0040] The heating jacket of this invention, in broad terms, has a cross-sectional structure comprising an inner layer 10, a heater 20, an intermediate layer 30, a graphite layer 40 and an outer layer 50. The inner layer 10 and outer layer 50 are exterior layers of the heating jacket of this invention. The inner layer 10 preferably directly contacts the object to be heated when the heating jacket is in use, and the outer layer 50 forms the outer surface (in the absence of additional layers, such as insulation or waterproofing layers) of the heating jacket preferably surrounding the object to be heated, such as a cylinder.

[0041] In addition, just as in a conventional heating jacket, the inner layer 10 adhered to or contacting the cylinder and the outer layer 50 are provided with an overheating prevention sensor 70 for preventing overheating of the cylinder and jacket. Additionally, temperature sensors 60, 80, which detect the temperature of the jacket and the cylinder, may also be installed. Still further the jacket may include hooks, clips, zippers, velcro or other attachment means (not shown) customarily used to attach the heating jacket to the object to be heated.

[0042] In addition, it is also apparent that cable connecting parts not indicated by reference numerals in the drawings are formed in the same manner as in the prior art, and the cable connecting parts and the cables too are electrically connected to the heater 20 and the respective sensors 60, 70, 80 when in use, as the means to supply electrical power and electrical connections respectively and to those parts. The temperature sensors may communicate with a controller (not shown) that may be used to cause the heater to increase or decrease its heat output and/or shut off the heater 20. [0043] FIGS. 2 and 4 show temperature sensors 60, 70 and 80. Temperature sensor 60 may be a Platinum resistance temperature sensor; and temperature sensor 80, may be a Type K thermocouple sensor; however, other types of known temperature sensors may be used in the heating jacket of this invention. [0044] The inner layer 10, intermediate layer 30, and outer layer 50 are preferably made of silicon-containing materials, and in particular, preferably consist of silicone rubber material. The silicon-containing materials making up those layers may be the same or different. In one embodiment, at least the intermediate layer 30 is silicon-containing material that exhibits adhesive performance when heated to a temperature above the maximum temperature of the heating jacket when in use, but at a lower temperature than the temperature that will degrade the performance of at least some of the other layers and/or the heater, depending upon the method of manufacturing the heating jacket. Useful silicone rubber layers are readily commercially available from numerous suppliers, including Rubber-Cal, Inc and Shenzhen Tandy Silicon & Rubber Co. In one embodiment, the silicone rubber layers used to make the intermediate layer, the outer layer and/or the inner layer may be the same and may be heat resistant to about 180°C to about 200°C.

[0045] The intermediate layer 30 is provided between the heater 20 and the graphite layer 40.

[0046] The heater 20 may be arranged in series or in parallel and may be connected to the cable connecting parts to generate heat by external power supply. The heater that converts electrical power to heat may be any commercially available heater known to be useful in a heating jacket.

[0047] Graphite 40 (also referred to as the graphite layer 40) is known to have excellent heat resistance, chemical resistance, high thermal conductivity and high electric conductivity. In this invention, the graphite 40 should be made of a soft material rather than a hard material, since it should be able to be wrapped and unwrapped or from around the cylinder. The graphite 40 may be prepared by continuously passing a precursor such as a casting film, phenol resin, polyamide resin, aramid resin, or a polyacrylonitrile resin into a drying chamber, carbonizing furnace, and graphitizing furnace to dry, carbonize, and graphitize the precursor. Or it may also comprise a resin component uniformly containing a graphite powder. Or it may be configured such that a plurality of graphites are attached to the surface of a soft sheet. Graphite layer materials that are useful in this invention are commercially available from GrafTech.

[0048] The graphite 40 preferably assembled between the intermediate layer 30 and outer layer 50, preferably exhibits electrical as well as thermal conductivity. Ordinary adhesives if used to attach the intermediate layer 30 and the outer layer 50 to the graphite may impair the thermal and/or electrical conductivity of the graphite. Plus, these layers should be bonded together so as to be able to wrap the cylinder without forming gaps or wrinkling between the layers.

[0049] To improve the adhesion, the graphite 40 preferably comprises a plurality of holes on the surface of the graphite or through the graphite layer to improve the bonding of the graphite layer 40 to said intermediate layer 30, and/or the outer layer 50. [0050] As shown in FIGS. 2 through 5, the plurality of holes 41 are formed on or through the surface of the graphite 40. The holes are formed in or through the graphite either at the time the graphite layer is manufactured or by punching the holes through the graphite layer (sheet) after manufacturing the graphite, using for example, a punching die tool in a press. The same tool can be used to create holes on the surface of (but not through) the graphite depending on the die and/or the pressure.

[0051] An adhesive layer 42 (that may be in the shape of a plug in the hole) is furnished that has been formed by at least partially filling the holes 41 with an added adhesive material or forming the adhesive material from at least the intermediate layer. The adhesive layer 42 fixes in place the intermediate layer 30 and outer layer 50 respectively on the inside and outside surfaces of the graphite layer 40. In some embodiments the adhesive layer fills a majority of the space defined by the holes, and more preferably fills the entire space defined by the holes (particularly after the application of heat and pressure). When the graphite 40 is fixed by the adhesive layer present in the uniformly arranged holes 41 , the multilayers (the graphite with the intermediate layer 30 and outer layer 50 above and below it) act as a single unit, the heat may be conducted uniformly therethrough, and the precision of temperature sensing may also be improved.

[0052] The adhesion between any and all of the layers can also be improved by using heat and pressure to improve the bonding process. For example, as shown in Figure 7, the intermediate layer 30 may be adhered to the graphite layer 40 by pressing the two layers together after the optional application of an added adhesive between those layers. The application of heat and pressure fuses the layers. In the absence of an added adhesive, the intermediate layer is softened by the application of the heat and pressure and flows into the holes 41 , thereby forming a fused multilayer assembly. [0053] The adhesive may be a layer and/or which may be in the shape of a plug, or both an adhesive layer and adhesive plug that are contiguous between the silicone layers; therefore the term "adhesive layer" may be used to describe thinner and thicker areas of adhesive between the layers or through the holes in a layer. The adhesive layer 42 may be in the shape of a plug when formed by at least partially filling the holes 41 with an adhesive, preferably filling the holes, so that the adhesive plug 42 fixes in place the intermediate layer 30 and outer layer 50 respectively on the inside and outside surfaces of the graphite 40. The adhesive may be made by softening the silicon-containing material used to make the intermediate layer or by using an added adhesive. If an added adhesive material is used, it can be any known commercially available adhesive material for this application, such as a polychloroprene based adhesive, such as those commercially available from 3M that can be spread on the graphite and/or intermediate layer and/or outer layer before the layers are brought into contact. In one embodiment of the method of making the heating jacket of this invention, the layers may be pressed together optionally with heating until the adhesive cures, dries or otherwise completes its bonding thereby forming the adhesive layer 42 between the layers.

[0054] In alternative embodiments the adhesive layer which, also or alternatively, may comprise a contiguous plug on one or both sides of the graphite layer and/or the adhesive present in the holes, may not comprise a separate added adhesive material applied between the layers and/or into the holes, but may instead be formed by heating the outer layer and intermediate layer with the graphite layer present between those layers to an elevated temperature, which causes the intermediate layer and/or the outer silicone rubber layer to become soft and sticky and to flow into the holes 42 in or through the graphite layer, thereby forming a fused multilayer assembly. In alternative embodiments the adhesive layer is formed while pressing the layers together, that is, by the simultaneous application of heat and positive pressure which causes the intermediate layer and/or outer silicone rubber layer to become soft and sticky and to flow (under pressure) into the holes 42 in or through the graphite layer. The silicone rubber that flows into the holes will adhere the intermediate and outer silicone layers to each other thereby fixing the graphite sheet in place between them and will also adhere the outer and intermediate (silicone rubber) layers to the surface of the graphite layer too. By selecting the correct hole size and spacing, the multiple (three) layers will create a durable fused multilayer assembly that acts as a single layer. Providing holes in or through the graphite layer provides improved adhesion between the otherwise smooth surface of the graphite layer and the one or more outer and intermediate (silicone rubber) layers. The just-described embodiment may be free of added-adhesive material, meaning without the addition of a separate adhesive material between the intermediate layer, graphite layer and outer layer and in some embodiments the heating jacket will be free of added adhesive material between the intermediate layer 30, heater 20 and inner layer 10 too. [0055] In alternative embodiments, in addition to the outer layer, graphite layer and intermediate layer, the heater and the inner layer will be assembled in a multilayer assembly as shown in Figure two and all layers (the outer layer, graphite layer, intermediate layer, heater and inner layer) of the multilayer assembly will be heated and preferably simultaneously placed under pressure to adhere all of the layers to each other simultaneously. The layers may comprise an added adhesive between the layers, for example between the heater and the inner layer and/or between the heater and the intermediate layer and/or as described above between one or more of the layers and in the holes; however, in alternative embodiments the heating jacket will be free of any added-adhesive material, except for the adhesive formed by heating one or more of the silicone rubber layers (particularly the intermediate layer) to soften them, to cause one or more of them to become sticky and/or to flow and adhere to each other (the intermediate layer and the inner layer and/or outer layer) and to the graphite layer and heater and/or alternative components and/or layers that may be present in the heating jacket. [0056] In some embodiments, the intermediate silicone rubber layer will be selected so that it is affected more by the heat and the pressure as compared to the affect that the heat and/or pressure has on the inner and outer layers. In these embodiments, the intermediate silicone rubber layer will become soft and sticky at a lower temperature and/or pressure than the outer and the inner silicone rubber layers of the heating jacket. In this way, both sides of the intermediate layer will become the adhesive layer that holds the (all five or more or fewer) layers together. The inner and outer silicone rubber layers may be selected to withstand higher temperatures and pressures before they soften to provide more durable exterior layers to the heating jacket. Additionally, the intermediate layer may be selected so that it is thinner than either the inner layer and/or the outer layer.

[0057] In the embodiment in which all five layers (or more or fewer) are heated and pressed together simultaneously, the resulting heating jacket, although comprising multilayers, by taking advantage of the strong silicone rubber to silicone rubber bonding and the bonding of the silicone rubber to the materials of the other layers throughout the heating jacket, the multilayers will be adhered together to form a fused multilayer assembly that behaves as if the heating jacket were a single layer.

[0058] To accomplish the bonding of the layers of the heating jacket, the temperature and pressure may be applied by a heated press, hot plate or the like. In one embodiment, the temperature may be applied by slowing heating the heating jacket to the temperature is necessary to soften the intermediate layer, which may be between from about 180 °C to about 200°C. In addition to the temperature, the press or plate provides a positive pressure to the multilayer assembly inserted therein and treated thereby. The best temperature and pressure will depend on the materials used to make the heating jacket and can be determined by simple experimentation based on the teachings herein. The press or plate preferably applies heat and/or pressure over the entire surface or substantially the entire surfaces of the heating jacket. The press or plate and the fused multilayer assembly may be cooled to below the softening temperature of the silicone rubber before removing the fused multilayer assembly from the plate or press.

[0059] In an alternative embodiment, one or more surfaces of the silicone rubber layers of the intermediate layer and/or outer layer and/or the inner layer can be pre-heated and assembled in a heated or ambient temperature press to adhere the layers together to form the fused multilayer jacket. In this embodiment preferably both surfaces of the intermediate layer are pre-heated. If the inner layer and/or the outer layer are also pre-heated, preferably, only the surface(s) of the outer layer and/or the inner layer that contact other layers of the multilayer assembly when assembled, that is, that will be on the interior of the fused multilayer assembly is(are) pre-heated. [0060] The holes 41 may be any shape. The holes are preferably arranged in a continuous repeating pattern over the surface of the graphite layer, preferably over the entire surface of the graphite layer. They may be an array of dimples on the surface or any shape void through the graphite layer, for examples, the holes may be eliptical-, rectangular- or square-shaped. In other embodiments, the holes may be circular-shaped. The diameter (or an effective diameter for non-circular shapes) of the holes may be from 8 to 12 mm and the distance between the centers of the holes may be from 20 to 30 mm. The diameters and spacing may vary depending upon the size of the heating jacket and the shape of the holes. If the holes are too big, the heat transferability may be compromised. Also, if the holes are too small the bonding area between the layers may be too small and the durability of the heating jacket may decline.

[0061] In one embodiment, as shown in Figure 7, the holes 41 optionally comprise a guide part 41 a formed, as shown, near the bottom of the hole, that is, where the hole meets the intermediate layer. The guide part has rounded corners and/or an increased or increasing diameter relative to the rest of the hole. The adhesive layer 42 (which may be silicone rubber that flowed from the intermediate layer and/or outer silicone rubber layers or may be an added adhesive material) at least partially filling the hole 41 is guided into the hole by the guide part 41 a. The guide part 41a, located between the intermediate layer 30 and graphite 40, helps to form the adhesive layer in the hole to firmly fix the graphite 40 and intermediate layer 30 in place. [0062] When guide parts 41 a are present in the holes after the graphite 40 has been placed on the intermediate layer 30 and the adhesive (either added adhesive material and/or formed adhesive from one or more of the silicone rubber layers by heating and pressure) is injected into or through the holes 41 , the adhesive smoothly seeps to the upper surface of the intermediate layer 30 (that is, to the surface of the intermediate layer in contact with the graphite layer) and into the guide part 41a.

[0063] By using this method of adhesion of this invention and the holes through the graphite layer, the graphite layer is better adhered to the layers contacting the graphite layer 40, such as the intermediate layer 30 and/or the outer layer 50. The holes provide for improved adhesion particularly between the fused silicone rubber layers relative to the adhesion between the typically smooth surfaces of the graphite layer without holes to which adhesives (either formed or added) do not always form a strong bond.

[0064] FIG. 6 shows an experimental result for a hole diameter of 10 mm and a center distance of 25 mm, and a comparison of an infrared image of a heating jacket using a Cu mesh layer at a temperature of 55 °C under natural convection conditions. The heating jacket using the Cu mesh has a maximum temperature of 57.9°C, while the heating jacket of this invention exhibits a lower maximum temperature of 56.5°C. However, the heating jacket of this invention had a more uniform temperature distribution overall, particularly in the area where the heater was located inside the heating jacket.

[0065] The heating jacket of this invention and made by the method of this invention had excellent adhesion and thermal conductivity. The surface temperature deviation is minimized, and improved thermal conductivity in all directions in the heating jacket of this invention.

Improving the thermal conductivity in the heating jacket improves the reliability of using a pointwise temperature measurement technique (for example, by using one or more of the temperature sensors 60,70, 80) to control the temperature of the heating jacket). The heating jacket of this invention also provides increased reliability and superior durability. [0066] The heating jacket of this invention may additionally comprise optional components for safety such as leak detectors, additional temperature sensors, etc. and layers such as one or more insulating layers and waterproofing layers, which may be added to the exterior of the outer layer.

[0067] In addition, the inner layer 10 and the outer layer 50, which are the exterior surfaces in the above-described configuration, may be formed at opposite positions to one another; in this case, the aforementioned sensors or cable connecting parts may also be formed in opposite positions.

[0068] Note the use of open terms such as "having", "comprising" and the like in the description above and in the claims that follow includes the more narrow terms, such as, "consisting essentially of" and "consisting of as if they were included in the description.

[0069] [Description of Symbols]

1 : Outer silicone layer

2: Ground layer

3: Intermediate silicone layer 4: Heat line

5: Lower silicone layer

6: Hook

6a: Hook mounting part 7: Overheating prevention sensor 8: Temperature sensor 9: Cable connecting part : Inner layer

: Heater

: Middle layer

: Graphite

: Hole

a: Guide part

: Adhesive layer: Outer layer

: Temperature sensor: Overheating prevention: K sensor