JP2010059036A - Carbon aggregate molded article and method for producing carbon aggregate molded article - Google Patents

Abstract

Carbon in which a coating film such as a fluorine-based resin formed for the purpose of suppressing adhesion of cooking utensils is a base material of a molded product while being able to reduce damage due to various stresses applied when used as a cooking utensil Disclosed are a carbon aggregate molded product and a method for producing a carbon aggregate molded product that can suppress cohesive separation from the aggregate and maintain high adhesion.
A carbon aggregate molded product according to the present invention has a surface modifier on the surface of a molded product obtained by using a molding material containing carbon powder particles and an uncured phenolic resin. Is applied, and this is fired at an oxygen-free high temperature.
[Selection] Figure 4

Description

  This invention is used in cooking utensils such as a rice cooker inner pot capable of electromagnetic induction heating, and is obtained by subjecting a molded product comprising carbon powder particles and a binder, which is a high carbon-containing material, to a baking treatment in an oxygen-free state. The present invention relates to an aggregate molded article and a method for producing a carbon aggregate molded article.

  The stove or rice cooker, which is an electromagnetic heating cooker, uses electromagnetic induction heating in which iron or stainless steel, which is a magnetic metal, generates heat due to eddy current generated by an induction heating coil, which is a high-frequency magnetic field generator. It is characterized in that the food can be heated quickly and uniformly. The electromagnetic heating cooker used a clad material laminated with aluminum or copper as a pot-shaped molded product, but the clad material is difficult to shape, such as a pan or kettle, and the surface is made of fluorine resin or the like. There were also problems such as peeling of each laminated interface on the heat-resistant resin coating surface.

  Therefore, when the pan is induction heated, eddy currents are easily generated in the pan, and the generated heat is easily and evenly transmitted to the entire pan, and the pan is deformed when the pan is manufactured. In order to prevent this, in the one provided with an induction heating coil that is provided so as to face the outer bottom surface portion or the outer peripheral surface portion of the pan and induction-heats the pan, and includes a control means that controls energization of the induction heating coil Since the pan is made of graphite having a carbon purity of 99.9% or more, an eddy current is easily generated in the pan during induction heating, and the generated heat is uniformly and quickly transmitted to the entire pan. Moreover, in the case of manufacturing the above-described pan, an induction heating cooker has been proposed in which the pan is not damaged or deformed during manufacturing, unlike the clad-made pan, and the quality of the pan is improved ( For example, see Patent Document 1).

  In addition, the conventional electromagnetic heating cooker suddenly becomes high temperature, and suddenly cools and heat efficiency is poor, and it is not suitable for grilled meat cooking such as grilled meat, and grilled meat with mild heat such as charcoal grill For the purpose of providing an electromagnetic heating cooker that can cook pottery and can retain heat for a long time even when the switch is turned off, it comes in contact with the high-frequency magnetic field generator in the casing from the carbon compression body. There have been proposed an electromagnetic heating cooker including a container and an electromagnetic heating cooker including a carbon compression molding tool (see, for example, Patent Document 2).

  In the method of manufacturing an induction heating cooker described in Patent Document 1 described above, a mixture mainly composed of a binder that is a high carbon content such as phenol or pitch is formed on carbon particles such as coke, and this is formed in an oxygen-free atmosphere. After obtaining a carbon aggregate obtained by heating at 1000 to 3000 ° C. below, it is cut into an arbitrary shape. However, cutting a carbon sintered body into an arbitrary shape has the problem that the material in the hollow part of the concave portion of the container that occupies most of the cutting is discarded and the number of processing steps is large. there were.

As a means to solve these problems, it was obtained after shaping by injecting and pressing a mixture of carbon powder particles and a phenol resin raw material liquid or a binder such as tar pitch into a mold. Means for obtaining a carbon aggregate formed into a pan shape by firing the molded product has been proposed (for example, see Patent Document 3).
JP-A-9-75211 JP-A-9-70352 JP 2007-44257 A

  The molding means of the above-mentioned patent document 3 uses carbon particles such as graphite by injection or the like and a high carbon-containing substance such as phenol resin that exhibits a liquid state at a molding temperature as a binder, and fills the mold with a molding material obtained by mixing them. , The formation of an unfilled portion due to the retention of gas such as air in the mold is suppressed, and uniform and high physical properties can be obtained by applying sufficient pressure. Therefore, in order to ensure the fluidity of the raw material, it is important to contain a large amount of binder, but on the other hand, to obtain a carbon aggregate molded product with excellent strength, electrical conduction, and heat conduction necessary for an electromagnetic heating cooker. It is necessary that the mixing ratio of the carbon particles is high. For this reason, there existed a subject that it was difficult to satisfy | fill these conflicting characteristics.

  In securing a molded product as an electromagnetic heating cooker, in a molded product in which many pores remain because sufficient pressure cannot be applied due to dense filling of carbon particles, in an oxygen-free atmosphere There was also a problem that the carbon aggregate subjected to the baking treatment suffers from various stresses that occur when cooking, as compared with the original resistance. Such a decrease in surface strength also has a problem that the adhesion of the coating film is low because the coating film is easily peeled off together with the substrate when the surface of the molded product is coated.

  In addition, by obtaining a mode in which the binder is reduced and a large amount of carbon particles are mixed as described above, a portion where the binder is not applied is easily formed on the surface of the carbon particles, and the fluidity is lowered. Along with this, there is a problem that pressure cannot be applied between the particles, carbon pores are not densely filled and many pores remain, and the strength and thermal conductivity of the baked aggregate are reduced.

  The present invention has been made to solve the above-described problems, and can reduce damage due to various stresses when used as a cooking utensil and is formed for the purpose of suppressing adhesion of cooking utensils. Manufacture of carbon aggregate molded products and carbon aggregate molded products that can maintain high adhesion by preventing the coating film such as fluororesin from agglomerating and peeling from the carbon aggregate as the base material of the molded product It aims to provide a method.

  The carbon aggregate molded product according to the present invention is obtained by applying a surface modifier to the surface of a molded product obtained by using a molding material containing carbon particles and an uncured phenolic resin. This is characterized by firing at an oxygen-free high temperature.

  The carbon aggregate molded product according to the present invention is obtained by applying a surface modifier to the surface of a molded product obtained by using a molding material containing carbon particles and an uncured phenolic resin. By baking this at a high temperature in an oxygen-free state, the strength of the surface of the carbon aggregate molded product can be improved.

Embodiment 1 FIG.
A method for manufacturing an electromagnetic heating cooker, in which the inner surface layer of a pot-shaped molded product obtained by compression molding a mixture of carbon particles and a binder is impregnated with siloxane as a modifier at the site, and then baked. The strength improving means for performing will be described in detail below.

  First, a phenol raw material solution obtained by diluting a carbon powder obtained by pulverizing petroleum coke at an oxygen-free high temperature (about 3000 ° C.) and graphitizing a lump to 0.3 mm or less with an alcohol solution The polymer is charged in a state in which carbon particles are uniformly dispersed. If the resulting semi-cured phenolic resin maintains the temperature up to the polymerization conditions leading to securing suitable fluidity and cured state, a molding material in which fine particles forming an emulsion state after the passage of an arbitrary reaction time can be obtained. can get.

  In this state, a semi-cured phenol resin as a molding material is in a state of being dispersed in an alcohol solution, and is also attached as a thin film to the surface of the carbon particles. This state is further continued, and another semi-cured phenol resin dispersed as fine particles is deposited on the semi-cured phenol resin thin film on the surface of the carbon particle, and excessive desorption of the precipitated resin is caused again. By repeatedly adhering the surface of another carbon particle to the thin film, it is possible to secure a dispersion including a molding material that forms a stable granular shape with the carbon particle as a nucleus as the degree of polymerization increases.

  In the above dispersion liquid, the composite dispersion liquid with the carbon powder particles is cooled to a state where the semi-curable phenolic resin adhering to the surface of the carbon powder particles dispersed in the alcohol solvent is not fused again to form granules. After fully solidifying in this state, the solvent alcohol was scattered and dried under reduced pressure. As a result, an uncured phenol resin is arranged on the surface of the carbon particles to form a substantially spherical shape having a diameter of 0.05 to 0.3 mm, and the raw material charge amount of the phenol resin is adjusted in advance to obtain a resin retention rate. Obtained a molding material of about 20 wt%.

  The molding material obtained by the above-mentioned means is formed by covering a sharp end surface of the carbon powder obtained by crushing the lump and forming a smooth surface, so that the gap at the time of pressurization in the mold is filled. Thus, it is easy to move to a suitable position, that is, it has a feature of excellent fluidity.

  Next, a means for obtaining a cooker composed of a carbon aggregate molded product that forms a pot shape in the mold from the molding material will be described in detail. First, in order to obtain a pot-shaped molded product, the mold is heated in advance to about 160 ° C., which is the curing temperature of the phenol resin as a binder, and an arbitrary amount of molding material is charged. At this time, it is important for the phenol resin to promote by-product water vapor and unreacted substances in the initial stage of the reaction, and to positively exhaust the generated gas so that it does not remain inside the molded product. Therefore, the time during which the viscosity at the time of flow accompanying the progress of the reaction does not become excessively high, in this embodiment, 20-40 seconds is maintained at a low pressure of about the contact pressure, and then the uncured phenol is repeatedly released after temporary mold release. The resin was melted and shaped into an approximate shape. Then, after the phenol resin is cured by leaving the molding material in a high pressure state so as to form the closest packing, in this embodiment, pressurizing at about 10 MPa for an arbitrary time, in this embodiment, 300 to 360 seconds, the mold The pot-shaped molded product A was taken out of the product.

  Next, in order to modify the surface of the carbon aggregate molded product obtained by baking at an oxygen-free high temperature, which is performed later, a modifier is applied to the surface of the pan-shaped molded product molded as described above. To make a cooker. This manufacturing process will be described with reference to the manufacturing process diagram of FIG.

  First, the pan-shaped product B is removed by means of applying a paint containing siloxane bonds, for example, composed of organosiloxane (hereinafter simply referred to as siloxane) by spraying or using a brush or the like on the surface of the pan-shaped product A taken out from the mold. Get.

  Alternatively, a means may be used in which siloxane is applied to the mold surface and a molding material is placed thereon to impregnate the surface layer portion before molding. In this latter method, since a high-viscosity siloxane compound is disposed on the mold surface, only the surface layer portion of the molding material in contact with the mold can be impregnated. A pot-shaped pot-shaped molded product C was also obtained by the same molding method as that for the body molded product A.

  Apart from this, using a molding raw material obtained by kneading a commercially available low melting point novolak type phenolic resin to the same carbon powder as in the present embodiment so that the content is 20 wt% and using an extruder. As in the case of obtaining the pot-shaped molded product in the present embodiment, in the mold by pressurizing at low pressure and high pressure in the mold heated to the curing temperature for obtaining the pot-shaped molded product. The phenolic resin was cured with to obtain a pot-shaped molded product as a comparative example.

  Any pan-shaped product thus obtained was allowed to stand in an oxygen-free atmosphere at about 1200 ° C. to carbonize the phenol resin to obtain a carbon-coagulated product molded into a pan-like shape.

  A product obtained by allowing the pot-shaped molded product A to stand in an oxygen-free atmosphere at about 1200 ° C. to carbonize the phenol resin is referred to as a carbon aggregate molded product A.

  Similarly, a product obtained by allowing the pot-shaped molded product B to stand in an oxygen-free atmosphere at about 1200 ° C. to carbonize the phenol resin is referred to as a carbon aggregate molded product B.

  Further, a product obtained by allowing the pot-shaped molded product C to stand in an oxygen-free atmosphere at about 1200 ° C. to carbonize the phenol resin is referred to as a carbon aggregate molded product C.

  Further, a comparative product of a pot-like molded product obtained by carbonizing a phenol resin by leaving it in an oxygen-free atmosphere at about 1200 ° C. is used as a carbon aggregate molded product of the comparative example.

  At this time, in order to prevent the decomposition product of phenol from staying inside the carbon aggregate molded product and staying inside and generating a fault crack, it is possible to increase the temperature stepwise. Essentially, in the vicinity of 350 ° C., 500 ° C., and 800 ° C., where the phenol resin is actively decomposed and suddenly loses its weight, the temperature gradually rises or is maintained. Specifically, the temperature was rapidly increased up to 300 ° C. at 0.5 ° C./min, then reached 350 ° C. at a moderate temperature increase of 1 ° C./hr, and then held for 5 hours. Furthermore, after reaching 450 ° C. at 5 ° C./hr, reaching 500 ° C. at 1 ° C./hr, holding for 5 hours, reaching up to 750 ° C. at 5 ° C./hr, reaching up to 800 ° C. at 2 ° C./hr, 3 I kept time. Furthermore, after that, the temperature was reached at 1200 ° C. at 0.5 ° C./min and held for 2 hours.

  Moreover, about cooling, it cooled to room temperature vicinity at 0.5 degree-C / min.

  Next, about the carbon aggregate molded product (carbon aggregate molded product A, carbon aggregate molded product B, carbon aggregate molded product C, and carbon aggregate molded product of the comparative example) having a pan shape prepared by the above means. In order to confirm the improvement in strength that is a modification effect in the surface layer of the molded product impregnated with siloxane during molding, the part was coated with a silicone resin, and the adhesion of the coating film was evaluated. Only the silicone resin paint is longitudinally and laterally spaced at intervals of 1 mm, each having 11 cuts in a checkerboard pattern, and confirming a defect portion caused by repeating the peeling operation of the tape adhered on this surface 10 times, The evaluation was based on the number of squares in the part without defects.

  The result of evaluation of those coating film adhesiveness is shown in FIG. Those in which the surface layer portion of the molded product was impregnated with siloxane (carbon aggregate molded product B and carbon aggregate molded product C) were all excellent in coating film adhesion and hardly had defects. On the other hand, in the carbon aggregate molded product of the comparative example, it was confirmed that defects occurred in almost half of the meshes, and in particular, the paint was peeled off with the carbon aggregate as the base material.

  In other words, by impregnating with siloxane and firing at a high temperature, the strength of the surface layer portion of the molded product was improved, and it was possible to sufficiently withstand the tensile stress caused by the tape peeling. It could be confirmed.

Embodiment 2. FIG.
For the inner pot of a rice cooker, which is an electromagnetic heating cooker obtained by firing a molded product by injection molding at a high temperature in an oxygen-free state, a mixture of the raw material carbon powder and a binder is injected into the mold. The means for improving the strength of the surface of the aggregate of the molded product obtained as described above will be described in detail below.

  First, carbon coagulates of 0.1 mm or less obtained by pulverizing lumps obtained by calcination of petroleum coke at an oxygen-free high temperature (about 3000 ° C.) to give a resin content of about 40 wt%. Add a diluted ethanol solution of phenol and mix under reduced pressure to fully wet the surface. Thereafter, excessive formaldehyde is added while continuing mixing so that the carbon powder particles are dispersed, and the mixture is heated to 50 to 80 ° C. and subjected to condensation polymerization. At this time, in order to obtain a phenol resin that has a fluidity and a suitable curing reaction, while suppressing the amount of gas such as water vapor, which is a by-product of curing that proceeds during injection and mold filling, polymerization of the uncured phenol resin It is important to control the degree.

  In the mixed liquid obtained by mixing the molding raw material, which is carbon powder holding an uncured phenol resin film, and dispersing it in ethanol and excess formaldehyde with respect to the above-prepared molding raw material, A heat-resistant thermoplastic resin in which a fine powder of polyamide that exhibits a marked decrease in viscosity due to pressure was added and dispersed in an amount equivalent to about 10% of the phenol resin was prepared. The polyamide fine powder used here is mixed and held with a phenol resin covering the surface of the carbon particles. Instead of polyamide, PBT resin (polybutylene terephthalate) may be used.

  As the reaction of these molding material raw materials proceeds, the phenolic resin solidifies, so that low-boiling point ethanol and excess formaldehyde are reduced in pressure while maintaining a low temperature so as to ensure a stable state in which this does not aggregate. By performing a drying treatment to be scattered below, an uncured phenol resin film was held on the surface of the carbon powder particles, and a molding raw material having a particle diameter of approximately 1 mm was obtained.

  The molding raw material obtained by the above-mentioned means is formed by forming a smooth surface by covering the sharp end surfaces of the carbon particles with an uncured phenol resin film, so that excellent kneadability can be obtained with an injection molding machine, When flowing in the mold after injection, the coating resin melts without causing the surface of the carbon particles to be almost exposed, and exhibits excellent fluidity.

  Next, means for obtaining a rice cooker inner pot by firing the obtained molded product in an oxygen-free high temperature atmosphere after injection molding using the molding raw material will be described in detail. A mold provided with a portion corresponding to the outer periphery of the inner hook opening as a gate is heated to about 160 ° C., which is the curing temperature of the phenol resin, and the molding material is filled from the gate. At this time, a mixture of polyamide and molding material particles has a much lower viscosity than a molding material that does not mix polyamide at the time of filling and improves apparent fluidity and is filled between raw material particles. Therefore, it is advantageous because it hardly affects characteristics of the cooking utensil such as strength and thermal conductivity, and hardly affects the fusion between the forming raw materials.

  In addition, the phenol resin obtained in the above-mentioned process promotes the diffusion of gas such as water vapor as a by-product in the initial stage of the reaction, and in order to ensure suitable fluidity in the mold, the cylinder is phenolic resin. It is adjusted at a temperature slightly higher than the melting point of the cylinder, and is removed by suction from a vent provided near the middle part of the cylinder under reduced pressure, or the inside of the closed mold is maintained in a reduced pressure state to facilitate discharge. Is effective.

  The molding material filled in the mold vaporizes the raw material mainly composed of phenol that did not contribute to the reaction with water vapor as a by-product of the reaction when the uncured phenol resin coated on the surface is cured. Since the released gas component is released, a smooth molded product surface can be secured by smooth discharge together with a molding material composition that minimizes this.

  In addition, at this time, by providing a fine convex shape on the mold surface, the high-viscosity raw material for molding can suppress adhesion to the mold surface, so that the phenolic resin is not completely cured at the time of demolding. Even if the strength is insufficient, the mold can be removed without causing damage such as peeling of the surface of the molded article. Therefore, the mold was opened 3 minutes after the completion of injection, and the molded article was taken out.

  The raw material for molding filled in the mold is cured by the phenolic resin covering the surface of the molding raw material. Since the surface of the obtained molded product contains a large amount of a phenol resin that has melted and reduced friction generated between the mold and contributed to an improvement in fluidity, and a polyamide supplemented with fluidity, it will be described later. Many fine pores exist as a result of the release of airborne substances accompanying the baking treatment under anoxic conditions.

  Also, at the firing stage where these pores are formed, the carbon powder and the phenolic resin have different expansion and shrinkage behavior during the firing process, so the generated stress generates defects such as fine cracks and the surface of the molded product. In order to promote a decrease in the strength of the molded product, the coating film applied to the surface of the molded product is likely to be lost with the destruction of the base material, and the apparent adhesion of the coating film is lowered, which is not preferable.

  Therefore, it is effective to apply a process of laminating a layer having higher strength on the surface of the obtained molded product. In the present embodiment, a high carbon-containing compound such as a copna resin, petroleum, and the like is used as a surface modifier. Coal tar was applied as a surface modifier. As a result, there is almost no defect on the surface of the molded product that occurs due to expansion or contraction with the carbon powder particles on the molded product surface. A reinforcing effect against film peeling can be brought about.

  Moreover, what gave the process which laminates | stacks the surface modifier which mixed easily degradable fibers, such as a pulp fiber, in the said high carbon content compound was also produced. This is because the easily decomposable substance is decomposed and diffused during the baking process after coating, so that uniform pores are generated in the surface layer portion. To get. That is, the high carbon-containing compound may comprise fine pores that are scattered traces of particulate matter or fibrous matter.

  The molded product that has undergone the above steps is obtained by carbonizing the phenolic resin on the substrate of the molded product and the high-carbon-containing compound that is the coating film on the surface in an oxygen-free atmosphere at about 1200 ° C. A carbon aggregate having a possible inner pot shape was obtained. At this time, in addition to the expansion and contraction behavior that causes cracks in the wall surface due to the decomposition accompanying the carbonization, the internal pressure of the molded product wall, particularly the portion close to the surface, increases due to the generation of gas, resulting in local swelling and Cracks may occur. In order to prevent this problem, it is important to dissipate the decomposition products without staying in the molded product, and it is effective to raise the firing temperature stepwise according to the amount of decomposition gas generated. In other words, in a temperature range that causes a sudden weight reduction accompanying the decomposition of the phenol resin, the temperature is controlled to be gradually increased or maintained. For example, 12 hours after increasing the temperature up to 300 ° C. at 3 to 5 ° C./hr. And further up to 600 ° C. is fired at a rate of temperature increase of 5 to 10 ° C./hr.

  However, among the molded products created in the present embodiment, for those in which polyamide, which is a thermoplastic resin, is dispersed, cracks caused by stress generated due to gas generation such as decomposition gas or thermal expansion or contraction In response to the occurrence, the stress locally generated along with the movement to the low stress load portion in the molded product including the outflow of the polyamide in the molten state is relieved. As a result, it became possible to promote the temperature rise during firing. As a result, as shown in FIG. 3, cracks did not occur even if the firing time was shortened. As a result, the conventional firing time of 20 days was achieved. On the other hand, it could be completed in about 2/3 of 14 days.

  The pot-shaped molded product made of the above-mentioned carbon aggregate needs to be coated for the purpose of improving wear resistance and antifouling property as a cooking utensil, and the paint used here is a pore formed by the firing. A silicone resin that is easy to impregnate inside and has excellent wear resistance and heat resistance was used on the outer surface. The paint impregnates many pores on the surface of the aggregate to promote firm fixation of the coating film due to the anchor effect. The peel strength of the obtained coating film was determined by performing the operation of peeling only the coating material by vertically and horizontally at intervals of 1 mm, making 11 cuts in a grid pattern on each surface, and bringing the tape into close contact with this surface. The number of defects that occurred due to repetition was confirmed and evaluated by the number of cells in the part without defects.

  Compared to the comparative example of the first embodiment, it is a molded product of a coagulated product obtained by applying a coplanar resin to the surface of a coagulated product obtained by baking an injection molded product (carbon coagulated product D), and a phenol resin. In addition to the molded product of the aggregate (carbon aggregate molded product E) provided with a coating film mixed with pulp fibers, the surface of the molded product mixed with polyamide is injected into the surface of the injection molded product, and then baked after the application of the copna resin. FIG. 4 shows the evaluation results of the coating film adhesion for the molded product (carbon aggregate molded product F). In the molded product described in this embodiment, the molded product, which is a carbon aggregate of a comparative example that has only a base material and does not have a modifier coating film, was peeled off with cohesive peeling of the base material. On the other hand, the carbon aggregate molded product D, the carbon aggregate molded product E, and the carbon aggregate molded product F were almost free from defects and exhibited significantly superior coating film adhesion.

  In this embodiment, a thermosetting resin such as a phenol resin is used as a binder or a surface modifier. Instead, carbon content such as tar pitch that exhibits fluidity at high temperatures is used. When a high substance is used, carbon is not sufficiently left after the decomposition products are scattered at the time of high-temperature firing, so that shrinkage and insufficient bonding force do not occur. Furthermore, since it has the behavior that it can move to the low stress load part in the molded product including outflow from the system and achieve homogenization, the shrinkage amount during firing based on uneven distribution of molding material and uneven distribution of binder during firing It is possible to obtain the effect of shortening the time required for the firing treatment as in the case of mixing polyamide of a thermoplastic resin, etc. I can do it.

Embodiment 3 FIG.
A frying pan-like cooker that is an electromagnetic heating cooker obtained by baking a molded product by compression molding at an oxygen-free high temperature, and is obtained by filling a mold with a mixture of carbon powder as a raw material and a binder. The means for improving the strength by modifying the aggregate surface of the molded product thus obtained will be described in detail below.

  An uncured novolak-type phenolic resin that is added as a binder to a carbon particle of 0.1 mm or less obtained by pulverizing a lump of graphite obtained by baking petroleum coke at an oxygen-free high temperature (about 3000 ° C.). Molding material adjusted to have a holding ratio of about 30 wt%, and a diameter of about 30 μm for promoting pore generation that promotes resin impregnation such as paint from the surface of the molded product after baking. 2 mm or less of polypropylene fiber (an example of an easily degradable fibrous resin) was added and mixed uniformly to prepare two types of molding materials.

  At this time, the easily degradable fibrous resin that enables the formation of pores that can be impregnated with the resin may be replaced with another thermoplastic resin, for example, an olefin resin such as polyethylene or polyamide, instead of polypropylene fiber. A granular resin may be used as long as it is a resin that can be melted in the molding stage and can intervene in the voids between the carbon powder particles and the novolac phenol resin particles.

  Next, compression molding is performed using the molding material composed of the above-described mixture. After the mold is heated to about 160 ° C., which is the curing temperature of the phenol resin, the molding material described above is put into the lower mold forming the outer surface to close the mold. At this time, the mold gap is kept so that the compression load is kept at a low level of contact pressure, and the water vapor generated in the initial stage of curing and the unreacted raw material gas such as formaldehyde are prevented from being diffused to stay inside the molded product. Consideration such as reducing the pressure inside is necessary. Therefore, after maintaining the contact pressure for 10 to 30 seconds, a pressure of about 10 Mpa was applied to secure a desired shape, and the mold was opened after 3 minutes from completion of injection to complete the curing, and the molded product was taken out.

  Next, a carbon agglomerate forming a cooker capable of electromagnetic induction heating is obtained by performing a baking treatment for carbonizing a phenol resin in an oxygen-free atmosphere at about 1200 ° C. At this time, in the temperature range that causes rapid decomposition of phenol resin, etc., in addition to cracks in the wall due to expansion and contraction behavior due to scattering of cracked gas, local in the vicinity of the surface layer due to internal pressure increase due to gas generation In order to prevent the occurrence of typical swelling and cracks, it is important to suppress the rapid generation of cracked gas by gradually increasing the firing temperature. For example, after heating up to 300 ° C. at 3 to 5 ° C./hr and holding for 12 hours, firing up to 600 ° C. at 1 to 3 ° C./hr and firing up to 1200 ° C. at a heating rate of 5 to 10 ° C./hr did.

  In addition, because the behavior of expansion and contraction when the temperature of the carbon powder and the phenolic resin is increased during the firing stage, the generated stress generates defects such as fine cracks and is applied to the surface of the molded product. The paint is lost along with the destruction of the base material, which causes a decrease in apparent adhesion.

  On the other hand, the molded product of the present embodiment is formed by melting the polypropylene fiber during molding and continuously holding the carbon particles, so that the molten state is maintained in the initial stage of the firing process described later. It decomposes to form continuous pores. For this reason, since the decomposition | disassembly gas of the phenol resin was provided with the effect which can be dissipated without staying in the inside of a molded article, the generation | occurrence | production suppression effect of a swelling and a crack in a molded article is acquired.

  Also, cracks that occur due to thermal expansion or contraction act as a relaxation behavior of the stress that accompanies expansion due to heating due to outflow from the system, etc., and cracks are less likely to occur. Thus, the temperature raising rate can be increased. As a result, compared with the conventional baking time of 20 days, the molded article made of the aggregate of the present embodiment could be completed in about 2/3 of 14 days.

  Next, the surface strength of the obtained molded product was subjected to a process of laminating a high strength layer, thereby improving the apparent strength on the surface of the molded product and obtaining high coating film adhesion. In the present embodiment, the surface of the molded product generated from the interaction such as the expansion of carbon particles and the shrinkage accompanying the firing of the phenol resin due to the application of a high carbon-containing compound as a surface modifier, such as a copna resin or a phenol resin. There are almost no fine cracks and the like, and the direct application of stress due to the peeling of the coating film is alleviated to provide a reinforcing effect against the peeling of the coating film.

  First, on the surface of a carbon condensation molded product obtained by baking an injection molded product, a mixture of a high carbon content compound copna resin diluted with ethanol and polypropylene fibers for decomposing and removing to form pores is used as a modifier. And then sufficiently impregnated.

  This was baked in an oxygen-free atmosphere at about 1200 ° C. similar to the molded product to assimilate with the carbon aggregate of the base material, and a surface layer capable of electromagnetic induction heating was retained. Since many pores are provided on the surface of the aggregate, the pores can be impregnated with a copna resin paint to firmly fix the coating film due to the anchor effect. Further, the copna resin itself has a feature that it has a very large amount of residual carbon due to baking at a high temperature in an oxygen-free state, and can exhibit sufficient strength as a base material for a coating film.

  Even if petroleum and coal tar are used as other high carbon-containing compounds, the carbon residual amount is very large and sufficient strength is exhibited after firing in an oxygen-free atmosphere at about 1200 ° C. as in the case of Copna resin. A surface layer that can be obtained was obtained.

  On the other hand, the same effect can be obtained by applying and impregnating a mixture of a siloxane compound such as organosiloxane and an uncured phenol resin as a surface modifier. In this case, at about 1200 ° C., which is the firing temperature of phenol and siloxane, both substances react to produce silicon carbide, and the excellent rigidity and strength thereof modify the aggregate surface.

  In order to obtain a practical function as a cooking utensil, the carbon agglomerated product obtained as described above is applied to the outer surface to provide a silicone resin excellent in wear resistance and heat resistance, and the inner surface is fixed to cooking utensils. The fluororesin coating material to suppress was applied, the predetermined drying process was performed, and the coating film was closely_contact | adhered and fixed.

  The peel strength of the coating film is generated by repeating the stripping operation of the tape adhered to this surface 10 times 10 times by placing eleven cuts in a grid pattern at intervals of 1 mm in the paint only at intervals of 1 mm. The missing part was confirmed and evaluated by the number of cells in the part without the missing part.

  Condensate molded product (carbon aggregate molded product G) calcined after application of copna resin, aggregate molded product (carbon aggregate molded product H) calcined after application of a mixture of siloxane and phenolic resin, coating The evaluation results of the film adhesion are shown in FIG. 5 together with the comparative example 2 shown in the second embodiment. The molded product described in the present embodiment is a coating of a mixture of phenol resin and carbon powder, which is a conventional aggregate molded product, whereas many coatings were peeled off with the base material. The coating film adhesion was significantly excellent with almost no defects.

  In this embodiment, a thermosetting resin such as a phenol resin is used as the surface modifier. Instead, a substance having a high carbon content such as petroleum tar that exhibits fluidity at high temperatures is used. Even if it is used (condensate molded product I), carbon does not remain sufficiently even if the decomposition products by high-temperature firing scatter, and shrinkage and insufficient bonding force do not occur. Since the same effect was obtained from the result of the adhesion of the coated film, it can be replaced.

  As described above, the coating layer formed on the cooking surface of the cooking utensil is obtained by making the surface of the aggregate molded article a strong surface layer of silicon carbide generated from a high carbon-containing compound and siloxane. It was confirmed that the adhesion performance can be greatly improved.

FIG. 5 shows the first embodiment and is a manufacturing process diagram of a cooking utensil. FIG. 5 shows the first embodiment, and shows the evaluation results of the coating film adhesion of the carbon aggregate molded product. The figure which shows Embodiment 2 and is a figure which shows the crack generation | occurrence | production situation of the carbon aggregate molded product (rice cooker inner pot) by polyamide presence or absence. It is a figure which shows Embodiment 2, and is a figure which shows the evaluation result of the coating-film adhesiveness of a carbon aggregate molded article. It is a figure which shows Embodiment 3, and is a figure which shows the coating-film adhesiveness evaluation result of a carbon aggregate molded article.

Claims (20)

  A surface modifier is applied to the surface of the molded product obtained by using a molding material containing carbon powder particles and an uncured phenolic resin, and this is fired at an oxygen-free high temperature. Carbon aggregate molded product characterized by   The carbon aggregate molded article according to claim 1, wherein the surface modifier is formed by applying a paint containing a high carbon-containing compound.   The carbon aggregate molded product according to claim 2, wherein the high carbon-containing compound is a copna resin.   3. The carbon aggregate molded article according to claim 2, wherein the high carbon-containing compound comprises tar of petroleum and coal.   3. The carbon aggregate molded article according to claim 2, wherein the high carbon-containing compound comprises fine pores that are scattered traces of particulate matter or fibrous matter.   Carbon aggregate molding characterized in that siloxane is applied to the surface of a molded product obtained by using a molding material containing carbon particles and an uncured phenolic resin, and then baked at an oxygen-free high temperature. Goods.   After applying a siloxane to the surface of a molded product obtained by curing a molding material composed of an uncured phenolic resin that has undergone a polymerization step while mixing an arbitrary amount of carbon particles while pressing in a mold, A method for producing a carbon aggregate molded article, which is obtained by decomposing an organic substance by baking treatment at a high temperature in an oxygen-free state.   The molding material, which is formed after placing a molding material composed of an uncured phenol-based resin that has undergone a polymerization stage while mixing an arbitrary amount of carbon particles on a mold surface coated with siloxane, or disposed in the mold A carbon aggregate molded article obtained by decomposing an organic substance by baking at a high temperature in an oxygen-free state after a siloxane is sprayed on the surface of the mold and cured while being pressed in a mold. Production method.   A surface modifier is added to the surface of a molded product obtained by curing a molding material composed of an uncured phenolic resin that has undergone a polymerization stage while mixing an arbitrary amount of carbon particles while pressing in a mold. A method for producing a carbon aggregate molded article obtained by decomposing an organic substance by baking treatment at a high temperature in an oxygen-free state after coating.   The method for producing a carbon aggregate molded article according to claim 9, wherein the molding material is a mixture of polyamide or PBT resin having a melting temperature that melts by heating during molding.   The method for producing a carbon aggregate molded article according to claim 9, wherein the surface modifier is formed by applying a paint containing a high carbon-containing compound.   The method for producing a carbon aggregate molded article according to claim 11, wherein the high carbon-containing compound is a Copna resin.   12. The method for producing a carbon aggregate molded article according to claim 11, wherein the high carbon-containing compound comprises tar of petroleum and coal.   The method for producing a carbon aggregate molded article according to claim 11, wherein the high carbon-containing compound is formed by mixing an easily decomposable particulate substance or fibrous substance.   After firing the molded product obtained by pressurizing and heating the molding material, which is a mixture of carbon particles, readily degradable fibrous resin, and phenolic resin uncured material, in a mold at an oxygen-free high temperature A method for producing a carbon aggregate molded article, in which a surface modifier is applied to the surface and subjected to a re-baking treatment at an oxygen-free high temperature.   The method for producing a carbon aggregate molded article according to claim 15, wherein the easily decomposable fibrous resin is made of an olefin resin.   The method for producing a carbon aggregate molded article according to claim 15, wherein the surface modifier is coated with a paint containing at least a siloxane compound.   The method for producing a carbon aggregate molded article according to claim 15, wherein the surface modifier is formed by applying a paint containing a high carbon-containing compound.   The method for producing a carbon aggregate molded article according to claim 18, wherein the high carbon-containing compound is a Copna resin.   The method for producing a carbon aggregate molded article according to claim 18, wherein the high carbon-containing compound is tar of petroleum and coal.

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