WO2004073905A1

WO2004073905A1 - Method of producing molds for lost wax precision casting

Info

Publication number: WO2004073905A1
Application number: PCT/JP2004/001734
Authority: WO
Inventors: Hidekazu Suzuki; Taro Kita; Akio Saito; Kazuki Kamata; Masato Kikuchihara
Original assignee: Shonan Design Co., Ltd.
Priority date: 2003-02-21
Filing date: 2004-02-17
Publication date: 2004-09-02
Also published as: EP1600229A1; JP4006696B2; US20060144555A1; JP2004261817A

Abstract

The problems of the invention are to establish a modeling resin composition excellent in shape retention and dewaxing properties in the skillful system which comprises a urethane resin easy of thermal decomposition, a plasticizer, and a wax or waxy component and a dewaxing method suitable for models made from the composition and to enhance the strength of a mold in the low-temperature region wherein dewaxing is carried out. According to the invention, a mold is produced by applying a primary layer consisting of plural refractory coating layers among which epoxy-silicone layers are laid and a backup layer consisting of plural thick coating layers on the surface of a resin model made by curing a two-part curable urethane resin fluid (F) which consists of a polyfunctional polyol component (A), a polyfunctional polyisocyanate component (B), a plasticizer (C), a wax or waxy component (D), and hollow resin balloons (E), preheating the obtained composite in a low-temperature region of 60 to 120°C for 2 to 8 hours to conduct initial dewaxing of removing 5 to 50% by weight of the resin model, raising the oven temperature gradually, and conducting the heating of the resulting composite in a medium-temperature region of 150 to 500°C for 2 to 5 hours and then the firing thereof in a high-temperature region of 500 to 1000°C for 2 to 5 hours.

Description

Description Lost Tox Manufacturing method for mold for precision manufacturing

In order to improve the shape retention, which is a drawback of the wax model used in the lost wax method, the present invention provides a method for removing the resin model in a mouth-strap precision manufacturing method using a resin model instead of a mouth model. The present invention relates to a method for manufacturing a mold for a lost-stroke precision manufacturing, which has sufficient strength and eliminates cracks in the mold. Background art

The following is an explanation of the entirety of the precision manufacturing method of the prior art as a conventional technique. The lost wax method is a method of manufacturing a mouth model having the same shape as a manufactured product by spray-molding a molten wax component into a mold for mass production of a mouth model, cooling, and demolding. The surface was coated with a refractory material, heated to melt and flow the wax model, completely burned out by high-temperature firing, manufactured a hollow mold, poured the molten alloy into the mirror mold, and cooled. After solidification, it goes through a manufacturing process that involves breaking the mold and removing the structure.

More specifically, this wax component is injection-molded into a mold to produce a wax model. The injection temperature, injection pressure, injection pressure holding time, and cooling / demolding temperature are controlled to produce a uniform quality wax model. Is done. The wax model manufactured in this way is stored in a constant temperature room at a constant temperature, and care is taken to maintain the dimensional accuracy as much as possible. To assemble this wax model, a wax model is brazed to a separately prepared gate model, and it is assembled in a tree-like shape. The entire assembled model is called Perry. Since the shape of the tree is the same as the gate system, the design takes into account many factors, such as the properties of the molten metal, the size and shape of the material, the manufacturing conditions, and the ease of cutting from the tree. Is designed.

The pellets produced in this way are repeatedly immersed in coating slurry and dried, and coated in layers. The binder used for the coating tree is colloidal silica, ethyl silicate, or the like. These binders are mixed with refractory fine powder as a filler to form a slurry. After the wax model is immersed in the slurry thus produced, the stucco particles are sprinkled and dried. Stucco grains include zircoside and morocite grains. By repeating these operations several times, the coating work is completed.

Next, in the autoclave, a wax model is eluted from the 铸 type at a temperature of 120-150 ° C. This is called dewaxing. After dewaxing, the shell 錶 is heated at 700 ° C to 100 ° C to improve the strength of the mold. Fired in a furnace. The molten alloy is injected into the mold thus manufactured, and after cooling, the mold is collapsed by a knock machine or the like. Is removed. Parts that can be repaired are repaired by welding, and the surface is finished with NC processing or grinders and heat treated to produce a ferrous alloy product.

Various studies have been made on the models used in the Rostock method. First, as a wax component of a wax model used as a model, a mixture of paraffin, rosin, carnauba wax, and terephthalic acid is generally used. The details of wax components are described in the Nikkei Handbook (edited by the Japan Food Association). In recent years, Japanese Patent Application Laid-Open No. 5-38549 discloses that the effectiveness of a wax component in which melamine powder is blended with a wax component Have been reported. It is considered that there is a limit in improving the mechanical strength properties of the mouthpiece as long as the mouthpiece keeps the property that it melts at a high temperature and it is easy to degas. In addition, as a model, there have been many reports of a system in which a synthetic resin and a wax model are laminated and united. For example, Japanese Unexamined Patent Publication No. 5-23791 discloses a model in which a synthetic resin film is formed on a wax surface. Japanese Patent Publication No. Hei 5-3 2 9 1 7 4 discloses a tooth binding model manufactured from a heated molten resin to form a model. Japanese Patent Application Laid-Open No. 7-90484 is a model in which a photo-curable resin sheet is laminated with a loss-storage table. Japanese Patent Application Laid-Open No. 7-295954 is a model in which an embroidery model made of cotton yarn or a synthetic material is coated with a plastic or plastic material. Japanese Patent Application Laid-Open No. Hei 7-474733 discloses a model in which a photocurable resin model or a heat-melting resin laminate model is inserted into a mold, and a molded article is formed by injection molding of a Lost Toxic resin. Japanese Patent Application Laid-Open No. 2000-26631186 is a model in which a lost wax table is laminated on an ultraviolet curable resin model. As described above, synthetic resin has been used for a part or the whole of a model, but this is mainly aimed at improving the shape retention of a wax model and producing a simple model.

As described above, it is known that a model using a synthetic resin is used as a substitute for a wax model in a precision structural loss method. However, when a resin model is used as a substitute for a wax model, it is difficult for the resin of the resin model to easily flow away during the dewaxing process, and in the vicinity of the temperature range where the resin of the resin model undergoes thermal decomposition, expansion and large amounts of combustion gas generate 铸 -type internal stress. It grows rapidly, causing hair-crack cracks in the 錄 type, and in some cases, type 崩壊 collapses. As described above, the resin model is not used in the dewatering process and the initial baking process, because it is difficult for the resin model to desorb and decompose and pyrolyze.

When manufacturing precision products by the Roto-Tax method, the model It is common to use a mouth model consisting of This takes advantage of the fact that the wax component liquefies above its melting point, easily desorbs and desorbs in the dewaxing process, and has excellent performance in complete combustion in the sintering process. However, in recent years, precision structures have come to have a complicated structure and demand strict dimensional accuracy. As a result, various issues have arisen, and in some cases, mouth-to-mouth models cannot be used.

In other words, the problems with these wax models are that the edges are hard to come out, the thin ribs are hard to stand, the thin ribs are easy to break, and thin parts must be removed with great care when removing the mold. However, there is a technical limit in the production of a wax model that has a part that is too thin, such as less than one restaurant. In addition, the produced wax model has problems that it is easily damaged due to its low surface hardness, has poor dimensional accuracy, and is damaged by drop impact when it is carried.In addition, the created wax model has a change in shape under summer conditions. There is a problem that it must be stored in a constant temperature room because it is easily caused. Furthermore, there is a problem that in the summer, when moving the wax model, great care must be taken. These are derived from the fact that the wax component is a relatively low-molecular-weight organic substance and softens at about 80 ° C. Thus, the problem of the mouth model concentrates on the problem caused by the wax component. In order to improve such problems caused by the wax component, improvement research has been conducted by changing the composition of the oral component, but the oral component is a low-melting organic substance that melts at a temperature slightly higher than room temperature. At present, the fundamental problem has not been solved because it is crystallized and solidified.

The present inventors have developed a resin model that promises to improve the defects of the wax model. The composition has been studied diligently. It is an object of the present invention to provide a resin composition for a model excellent in shape retention and opening property in a system in which a plasticizer and a mouth / box component are skillfully blended with a urethane resin that is easily decomposed. It is necessary to set a method of opening that is suitable for the resin model, and to reinforce the mirror mold in the low-temperature region to be dewaxed. Disclosure of the invention

Accordingly, the present invention comprises a polyfunctional polyol component (A), a polyfunctional polyisocyanate component (B), a plasticizer (C), a wax-wax component (D), and a hollow resin balloon (E). Process of mixing two-component reaction-curable urethane resin liquid (F), casting into mold (G), curing and demolding to produce resin model (H): into fire-resistant coating liquid (I) After the resin model (H) has been immersed, the resin model (H) is pulled up and dried, and the operation of applying an epoxy silicon (N) to its surface, drying and curing to form a coating layer is repeated several times. Manufacturing a primary layer consisting of a plurality of coating layers laminated on the surface of the resin model (H) Process: immersing the resin model (H) in the refractory coating liquid (I) Sprinkle with stucco (M) to dry The process of applying, drying and curing the oxysilicon (N) to form a thick coating layer is repeated a plurality of times, starting with the thick coating layer laminated on the surface of the resin model (H). Step of manufacturing a backup layer made of: A resin model (H) coated with a thick refractory coating multilayer consisting of the primary layer and the backup layer described above is placed in a furnace with a gate facing down. Pre-heating in the low temperature range of ~ 120 ° C for 2-8 hours to initially dewax 5-50% of the resin model weight: 150-500 ° C by gradually increasing the furnace temperature In the medium temperature area, heat for 2-5 hours, Evacuation of the resin model: a step of terminating combustion: and a step of firing for 2 to 5 hours in a high temperature range of 500 to 1000 ° C.

Furthermore, the average number of functional groups of the polyfunctional polyol component (A) is 2.8 or more, the average number of functional groups of the polyfunctional polyisocyanate component (B) is 2.0 or more, and NCO / OH is 0.8 to 1 0 is desirable.

Furthermore, it is desirable that the plasticizer (C) is phase-separated and micro-dispersed during the reaction curing of the two-component reaction-curable urethane resin liquid (F). The two-component reaction-curable urethane resin liquid (F) preferably contains 2 to 20% by weight of a polyether chain represented by the following chemical structural formula.

-(CH ₂ CHO) n- R: H or CH ₃

I n: 1-5 0

R

Further, the mouthwash component (D) is in the form of a powder having a melting point of 60 to 130 ° C and a maximum of 5 mm, and is contained in the two-component reaction-curable urethane resin solution (F) in an amount of 3 to 30%. Desirably, it is contained by weight.

Furthermore, it is desirable that the epoxy silicon (N) comprises a bisphenol-type epoxy (J), an aminosilane (K), and an organic solvent (L).

The hollow resin balloon (E) has a particle diameter of 10 to LOO m and a true specific gravity of 0.01 to 0.03, and the two-part reaction-curable urethane resin liquid (F) It is desirable that the content is 0.001 to 0.5% by weight. BEST MODE FOR CARRYING OUT THE INVENTION

A method for manufacturing a mold for loss-to-truss precision manufacturing using the resin model of the present invention. It will be explained in the process.

In the first step of the production of a mold for lost-package precision manufacturing using a resin model, a polyfunctional polyol component (A), a polyfunctional polyisocyanate component (B), a plasticizer (C), and a wax '' A two-component reaction-curable urethane resin solution (F) composed of a wax component (D) and a hollow resin balloon (E) is blended, and the two-component reaction-curable urethane resin solution (F) is molded ( Cast it into G), cure it, remove it, and make a resin model (H).

In the first step, the binder component of the two-component reaction-curable urethane resin liquid (F) is composed of a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B). The plasticizer (C), wax component (D) and hollow resin balloon (E) are additive components. The plasticizer (C) may be added to the polyfunctional polyol component (A), or may be added as one component when producing the polyfunctional polyol component (A). Further, the plasticizer (C) may be added to the polyfunctional polyisocyanate component (B), or may be added as one component when producing the polyfunctional polyisocyanate component (B). .

Further, the wax component (D) may be added to the polyfunctional polyol component (A), or after the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) are blended. It may be added. Furthermore, the wax component (D) may be added to the polyfunctional polyisocyanate component (B), or the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) are blended. It may be added after the addition.

The hollow resin balloon (E) may be added to the polyfunctional polyol component (A), or may be added after the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) are blended. good. In addition, the The hollow resin balloon (E) may be added to the polyfunctional polyisocyanate component (B).

In this manner, a two-part liquid composed of the polyfunctional polyol component (A), the polyfunctional polyisocyanate component (B), the plasticizer (C), the wax component (D), and the hollow resin balloon (E) A reaction-curable urethane resin liquid (F) is blended and cast into mold (G).

As the mold (G), a mold, a simple mold, a resin mold and a silicone rubber mold are applicable. The mold is suitable for mass production, the simple mold and resin mold are suitable for medium-volume production, and the silicone rubber mold is suitable for small-lot trial production. Die · Simple mold-The resin mold is designed with a draft angle, but in the case of a silicone rubber mold, the mold design with a draft angle is not an absolute requirement. In other words, due to the rubber elasticity, the silicon rubber mold is slightly bent, the model is taken out, and if the bending stress is released, the original shape can be restored. However, if used many times, rubber elasticity will be lost, so the limit is about 20 moldings. Therefore, it is suitable for small-scale trial production.

The two-component reaction-curable urethane resin liquid (F) poured into the mold (G) causes a chemical reaction at room temperature and cures for a set time. After curing and maintaining the shape, the mold is removed and the resin model (H) is taken out. It is common practice to apply a mold release agent to the mold (G) to be used and dry it beforehand.

In the second step, the resin model (H) is immersed in the refractory coating liquid (I), pulled up and dried, coated with epoxy silicon (N), dried and cured, and then cured. The operation of forming a refractory coating layer on the surface of (1) is repeated a plurality of times, for example, 2 to 5 times, to form a primary layer in which a plurality of refractory coating layers are laminated. That is, in the second step, when the resin model (H) is immersed in the refractory coating liquid (I) and pulled up, the refractory coating liquid (I) adheres to the surface of the resin model (H). Come up. This was dried, and epoxy silicon (N) was applied to the surface of the refractory coating layer of the resin model (H), and was dried and cured, and the surface of the resin model (H) was refractory coated. A tinting layer is formed. By repeating this operation 2 to 5 times, a single layer of bram- ary consisting of two to five refractory coating layers is formed. The epoxy silicon (N) is a solvent-diluted low-viscosity liquid, which is entirely or partially coated by spraying. The refractory coating solution (I) usually needs to be dried for half a day to one day, whereas the epoxy silicon (N) is formed by drying for one to three hours.

Since the primary layer is transferred to the skin of an animal, it contains a relatively fine filler and forms a dense refractory coating layer. The primary layer is preferably formed by repeating several times. If a thick film is coated at once, cracks will be generated at the time of drying, so it is necessary to apply it again.

Next, in the third step, the resin model (H) is immersed in the refractory coating liquid (I), pulled up, sprinkled with stucco (M), dried, and coated with epoxy silicon (N). Then, it is dried and cured to form a thick refractory coating layer on the surface of the resin model (H). By repeating this operation 2 to 5 times, a thick backup layer composed of 2 to 5 thick refractory coating layers is formed.

In the third step, the resin model (H) is immersed in the refractory coating liquid (I), pulled up, sprinkled with stucco (M) before drying, and dried. Then, apply epoxy silicon (N) and dry After drying and curing, a thick refractory coating layer is formed on the surface of the primary layer of the resin model (H). This operation is repeated two to five times to form a thick back-up layer in which two to five thick-film refractory coating layers are laminated. In other words, a thick film can be obtained by sprinkling stucco (M) and attaching it.

In the second and third steps described above, the resin model (H) is laminated on the primary layer, which is densely laminated in the structure in which the epoxy silicon (N) layer is provided between the refractory coating layers, and on the thick film. Will be covered with the backup layer. That is, the layer composed of the refractory coating liquid (I) ^ and the epoxy silicon (N) layer are alternated. The refractory coating does not exhibit significant strength in the low temperature range of 60 to 120 ° C. It is baked in a high temperature range of 500 to 1000 ° C and develops strength to form a kind of ceramic layer.

On the other hand, the layer made of epoxy silicon (N) is completely formed at room temperature and has a heat-resistant three-dimensional network structure, so it consists of a primary layer and a backup layer in a low temperature range of 80 to 200 ° C. It gives strength to the refractory coating layer. It is supposed that it burns in the high temperature range of 500 to 1000 ° C and loses its intensity. Therefore, by providing a layer made of epoxy silicon (N) between the layers and superimposing it, the D-type strength in the low temperature region is remarkably improved.

Next, in the fourth step, the resin model (H) having the primary layer and the backup layer formed on the surface of the と -shape is placed in a furnace with the gate facing down, and the resin model (H) is heated at 60 to 120 ° C for 2 to 2 hours. Perform preheating for 8 hours to dewax 5 to 50% of the weight of the resin model.

In the fourth step, the plasticizer (C) and the wax component (D) are softened or preheated by preheating at 60 to 120 ° C for 2 to 8 hours. Melts and gradually oozes from the inside of the resin model (H) to the surface of the resin model (H). In this temperature range, no combustion gas is generated, and the 応力 -type internal stress is due to the expansion of the resin model (H). The 鍩 -type consisting of the refractory coating layer is significantly compensated by the layer made of epoxy silicon (N). Since it has been strengthened, cracking will not occur at this level.

The exuded plasticizer (C) and wax / wax component (D) accumulate in the gap between the resin mold (H) and the mold, and penetrate into the porous mold inner surface, and the increase in mold pressure is reduced. Is done. When the accumulation of the wax component (D) further increases, it slowly descends and begins to dewax by dripping from the gate. Once the dewaxing phenomenon occurs, a dewaxing passage is created, after which dewaxing proceeds sequentially. If the temperature is raised so that it passes through this process in a short period of time, the combustion temperature will rapidly rise and the decomposition gas will accompany, so the internal pressure of the mold will rise sharply and the layer made of epoxy silicon (N) Even though it is a significantly reinforced type II, it will crack.

In the fourth step, when the preheating at 60 to 120 ° C. is performed for 8 hours or more, the process time becomes long, and there is no cost efficiency. In addition, within 2 hours, the plasticizer (C) and wax component (D) did not exude sufficiently and dewaxing did not proceed. Therefore, the preheating time is preferably 2 to 4 hours at 60 to 120 ° C. Then, it is preferable to initially dewax 2 to 20% of the resin model weight.

Next, in the fifth step, the furnace temperature is gradually increased, and heating is performed at 150 to 500 ° C. for 2 to 8 hours to complete the dewaxing and burning of the resin model.

In the fifth step, a two-component reaction consisting of a polyfunctional polyol component (A;), a polyfunctional polysocyanate component (B), a plasticizer (C), a wax component (D), and a hollow resin balloon (E) Curable urethane resin liquid (F) The hardened material is thermally decomposed and melts while generating decomposition gas, and the liquefied material tries to flow out. At this time, an outflow passage has already been formed between the resin model (H) and the mold 、, and the liquefied liquid that has melted from this passage tries to flow out through this outflow passage. At this time, the internal pressure of the mold 錶 due to the decomposed gas becomes a force to push out the molten and liquefied substances, so that the dewaxing proceeds smoothly and the decomposed gas is also discharged smoothly. Hair cracking is avoided.

Next, in a sixth step, the mold is fired at 500 to 100 ° C.

In the sixth step, the resin model is burning, and the mold is fired to reach the highest strength. After that, the mold is cooled slowly and the ash remaining in the mold is removed to complete the mold without cracks or hair cracks. Next, the components of the two-component reaction-curable urethane resin liquid (F) used in the present invention will be described.

The backbone of the two-part reaction-curable urethane resin liquid (F) is composed of two parts, a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B). The reaction is started and generates heat and hardens. The plasticizer (C) and wax / wax component (D) contained in the two-component reaction-curable urethane resin solution (F) are either polyfunctional polyol component (A) or polyfunctional polyisocyanate component (B). Or both.

Examples of the polyfunctional polyol component (A) include low molecular weight polyols, polyester polyols, amine polyols, polyester polyols, acryl polyols, and butadiene polyols. Low-molecular-weight polyols include ethylene glycol, propylene glycol, 1- to 4-butanediol, glycerin, trimethylolpropane, and pen-erythri. And tolls. As polyether polyols, polyether polyols of various molecular weights obtained by adding ethylene oxide to propylene oxide to the above low molecular polyols are commercially available. The terminal hydroxyl group becomes primary or secondary by various addition methods such as addition of ethylene oxide alone, addition of propylene oxide alone, mixed addition, and sequential addition. Due to this, the reactivity of terminal hydroxyl groups is different, and polyether polyols having various hydrophilicity depending on whether the added chain is ethylene oxide or propylene oxide are commercially available.

The amine polyol is obtained by adding ethylene oxide to propylene oxide to a low molecular weight amine such as ammonia ethyl diamine. Therefore, it contains tertiary nitrogen in the molecule, and is a polyol possessing the effect of promoting the reactivity of isocyanate. It is an essential component of the present invention that performs rapid curing.

Polyester polyol is obtained by esterifying a dibasic acid and a low molecular weight diol to form a hydroxyl group at the molecular end. By selecting and adjusting the type of dibasic acid and low molecular weight polyol, adjusting the molecular weight, and using a small amount of polyfunctional low molecular weight polyol, a wide variety of polyester polyols can be obtained. There is also a lactone polyester polyol obtained by ring-opening polymerization of £ -prolactam. By adding an alkylene oxide to these, some have a polyester chain and a polyether chain, and are very diverse.

Acryl polyol is a polymer obtained by polymerizing methyl acrylate / methyl methacrylate with an acryl monomer having a terminal hydroxyl group, and is an acryl polyol having a plurality of hydroxyl groups in an acryl chain. Various acryl polyols formed by selecting the type of acrylic monomer and adjusting the molecular weight are commercially available. Film formation The resin solution, which has increased the degree of polymerization to a high level, polymerized, and dissolved in an organic solvent, becomes a paint with excellent weather resistance by performing a slight cross-linking with aliphatic polyisocyanate. Butadiene polyol is a copolymer of butadiene having a hydroxyl group at a terminal and a compound having a double bond. A relatively hydrophobic polyol.

These polyfunctional polyols may be joined with a polyisocyanate to form a urethane-modified polyol having a terminal hydroxyl group. Due to the urethanization modification, the oligomer is oligomerized and the molecular weight is slightly increased, so that the viscosity tends to increase. Therefore, it is preferable that a part of the polyfunctional polyol is a urethane-modified polyol.

The polyfunctional polyisocyanate component (B) is a compound containing two or more isocyanate groups in one molecule, and the polyol component is a compound containing two or more hydroxyl groups in one molecule. . The isocyanate group is a very reactive functional group and reacts with a hydroxyl group having active hydrogen, an amino group or a thiol group. Amino groups and thiol groups react instantaneously, so they are limitedly applied to poorly reactive isocyanate components and poorly reactive aromatic amines, etc., but still react more quickly. The combination is not heavily used.

The polyisocyanate component includes an aromatic polyisocyanate, an aliphatic polyisocyanate, and an alicyclic polyisocyanate. Representative examples of aromatic polyisocyanates include tolylene diisocyanate and diphenylmethane diisocyanate. Tolylene diisocyanate is obtained as a mixture of various isomers due to the chemical reaction at the time of production, and industrially, TDI-100 (2,4) is obtained by a mixing ratio of 2,4-isomer and 2,6 in one. -TD I 100%) ヽ TD A 80 (2,4—TDI 80% 2,6 -TD I 201 1%), TDI—65 (2,4—TD I 65% 2, 6-TDI 35%) is commercially available. The diphenyl methanediisocyanate is also obtained as a mixture of various isomers due to the chemical reaction at the time of production, and there are industrially pure MDI and polymeric MDI. Pure MDI is binuclear, polymeric MDI is polynuclear, pure MDI is isolated by distillation, and polymeric MDI remains in the bottom. Polymeric MDI is commercially available from various manufacturers, because the number of polynuclei varies depending on the production conditions. Also, naphthalene nuclei include naphthalene dicysinate 1 and naphthylene dicysinate which have a group 1 in the naphthalene nucleus. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and lysine diisocyanate. Examples of the alicyclic polysocyanate include hydrogenated xylylene disocyanate—hydrogenated xylylene disocyanate—MDI and hydrogenated MDI.

Because polyisocyanate is highly reactive, volatile polyisocyanate is highly toxic and is used after various modifications. Examples include urethane modification, dimerization, trimerization, polycarbazimidation, urea modification, prepolymerization, and blocking. These are self-condensed utilizing the high reactivity of the isocyanate group, or are joined via an active ingredient to leave the isocyanate group at the terminal.

The two-component reaction-curable urethane resin solution (F), which comprises a polyfunctional polyol component (A) and a polyfunctional polysocyanate component (B) as resin components, comprises a polyether polymer represented by the following chemical structural formula. It contains 20% by weight. One (CH ₂ CHO) n- R: H or CH ₃

I n: 1-5 0

R

When a polyether is used for the polyfunctional polyol component (A), a polyester chain is introduced. When using a polyester polyol, a polyether ester means that a polyether chain has been introduced. If the polyfunctional polyisocyanate component (B) is a terminal isocyanate joined with a polyether, a so-called quasi prepolymer, a polyether chain has been introduced.

This polyether chain is a soft component, and when heated to a high temperature in the dewaxing / firing process, it is thermally decomposed. .

The blending amount of the polyisocyanate component and the polyol component is designed so that the number of NCO groups and OH groups is calculated, and the ratio of the number of NCO groups to OH groups (NCOZ OH) is usually around 1.0. (NCOZ〇H) = 1.0 is a design in which the number of isocyanate groups and hydroxyl groups are the same, and the reaction ends exactly. That is, it is a region where the highest strength is exhibited. In the present invention, by setting the average number of functional groups of the polyisocyanate component to be at least 2.1 and the average number of functional groups of the polyol component to be at least 3.0, it is possible to obtain an NCOZOtHl. It is set to 7 to 1.0. Preferably, it is 0.8 to 0.9. If the NCOZOH falls below 0.7, the isocyanate group will be in a severely shortage state, failing to obtain a three-dimensional network structure after reaction hardening, causing an extreme decrease in hardness, and eventually becoming soft enough to make the shape retention difficult. On the other hand, if the NCOZOH is 1-0 or more, the isocyanate group becomes excessive, and the unreacted isocyanate group remains even after the demolding time. Phenomena such as uneven coloration or foaming of the cured product surface occur. Examples of catalysts that promote the chemical reaction between the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) include a metal catalyst and an amine catalyst. Examples of the metal catalyst include zinc octoate / lead octoate, dibutyltin dilaurate, dibutyltin diacetate, and the like. Examples of the amine catalyst include triethylenediamine, NN-dimethylbiperazine, and N-methylmorpholine. These catalysts are usually added to the polyol component. Usually 1 to 1000 ppm is added to the polyfunctional polyol component (A) to adjust the pot life. In the present invention, a catalyst is added to the polyfunctional polyol component (A) so that the pot life, that is, the pot life is within 5 minutes. If the pot life exceeds 5 minutes, the curing demold time will be 2 hours or more, which will hinder resin model production. Therefore, the pot life is preferably 1 to 2 minutes.

The plasticizer (C) used in the present invention is a compound having no functional group that causes a chemical reaction and having negligible inert volatility, and preferably a liquid at room temperature. Examples of the plasticizer (C) include an ester plasticizer, an ether plasticizer, and an ester ether plasticizer. Specifically, representative examples of the ester plasticizer include octyl adipate (DOA), octyl phthalate (D0P), and dibutyl phthalate (DBP). In addition, benzyl acetate, butyl benzoate, octyl benzoate, isopentyl benzoate, ethylene glycol benzoate diester, polyethylene glycol benzoate diester, propylene glycol benzoate diester, polypropylene glycol benzoate diester, ethylene glycol geo Acrylate, polyethylene glycol dioleate, propylene glycol dioleate, polypropylene glycol dioleate and the like. Ethylene plasticizer is ethylene Glycol butyl ether, ethylene glycol diphenyl ether, diethylene glycol dimethyl ether, methylene glycol methyl ethyl ether, diethylene glycol methyl dimethyl ether, dimethylene glycol ethyl butyl ether, dimethylene glycol dibutyl ether, triethylene glycol Dimethyl ether, triethylene glycol dimethyl ether, triethylene glycol dibutyl ether, troethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol monomethyl ether, and the like. Examples of the ether ester include ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and diethene glycol monomonophenyl ether acetate.

The amount of the plasticizer (C) used is 2 to 20% by weight based on the two-component reaction-curable urethane resin liquid (F). If the amount of the plasticizer (C) used is higher than 20% by weight, the plasticizer (C) bleeds to the surface of the resin model, causing stickiness and sunset. When the amount of the plasticizer (C) is less than 2% by weight, the resin is thermally decomposed, melted, lost, and burned out in the dewaxing / firing process, so that the resin is hardly discharged. This is because the plasticizer (C) is a liquid at room temperature and has a low viscosity that easily flows out at high temperatures. In order to exert such effects strongly, it is desirable to contain the plasticizer (C) as high as possible.

As a result of intensive studies to increase the content of the plasticizer (C) as much as possible, it was rapidly cured within a pot life of 5 minutes, and the plasticizer (C) phase-separated from the cured resin, resulting in a three-dimensional cured resin. It has been found that it is effective to achieve a state of being confined in a micro-dispersed state within the network structure. Such a phase In a word, the separated microdispersion structure can be described as the presence of a plasticizer (C) that becomes a larva in a honeycomb-shaped cured resin. The honeycomb-shaped cured resin has a structure with excellent strength and physical properties, and has a structure in which the plasticizer (C) is carefully preserved in the honeycomb and is not released to the outside. Therefore, even if the content of the plasticizer (C) is relatively high, the plasticizer (C) does not ooze out on the surface of the cured product, and does not cause the generation of the evening sun. If a phase-separated micro-dispersed structure is not adopted, the plasticizer dissolves in the cured resin, and when it becomes saturated or more, the plasticizer oozes out on the surface of the cured product and tacks out. If there is much oozing, stickiness is likely to occur. Such a phase-separated microdispersion structure has been confirmed by electron microscopy. To promote the phase-separated microdispersion structure, it is necessary to rapidly cure within 5 minutes of the pot life. It is preferably within 3 minutes. If the pot life exceeds 5 minutes, phase separation microdispersion becomes difficult to complete, and it takes one day or more to remove the mold when making the model, and the speed of model production is lost.

When present as a two-part reaction-curable urethane resin liquid (F), the plasticizer (C) needs to be in a homogeneously dissolved state. At the stage of reaction curing, phase separation micro-dispersion from the cured resin is promoted, At the end of curing, it contains a plasticizer dispersed in the mouth and prevents bleeding to the surface. The composition is based on such a delicate balance. In other words, it is designed in a region where the balance between the hydrophilicity and hydrophobicity of the plasticizer (C) and the reaction curable resin is well adjusted. An alkylene oxide chain is effective as a hydrophilic segment, and a hydrocarbon chain is effective as a hydrophobic segment. These hydrophilic and hydrophobic segments are determined by the selection of the raw material monomers to be used. The balance between hydrophilicity and hydrophobicity needs to be designed to some extent. Excessive use of ethylene oxide chains in two-component reaction-curable urethane resin liquid (F) When propylene oxide chains are used, hydrophilicity becomes stronger, and when propylene oxide chains are used, the hydrophilicity becomes weaker than when ethylene oxide chains are used. When the number of ethylene oxide chains / propylene oxide chains is reduced, a two-part reaction-curable urethane resin liquid (F) having high hydrophobicity can be obtained, and the hydrophilicity and hydrophobicity can be adjusted within a certain range. In addition, by adjusting the type and amount of the plasticizer (C), the hydrophilicity and hydrophobicity of the plasticizer (C) itself can be adjusted within a certain range. For example, when the terminal is an alkyl ether, the hydrophobicity increases as it changes to methyl ether, ethyl ether, butyl ether, and phenyl ether. In this manner, the chemical structure and amount of the plasticizer (C) and the chemical structure and amount of the two-component reaction-curable urethane resin solution (F) are changed to set the range of the phase separation microdispersion.

The plasticizer (C) is liquid at room temperature. The plasticizer (C) is encapsulated in the resin in a micro-dispersed state in the resin model where the two-component reaction-curable urethane resin liquid (F) is cured. Therefore, when the resin begins to undergo thermal expansion and partial thermal decomposition and melting in the dewaxing and firing steps, the plasticizer (C) exudes from the resin model as a high-temperature, low-viscosity liquid. That is, it contributes as a leading component for improving the dewaxing property.

Next, the wax component (D) used in the present invention will be described.

Wax occurs naturally and is typically a candle. The chemical composition of wax is an ester composed of higher fatty acids and higher alcohols, and is called wax ester. Higher fatty acids and higher alcohols mainly contain 16 or more carbon atoms. Since it is an ester compound, some acid value remains. That is, free fatty acids remain. In addition, since a large number of saturated and unsaturated higher fatty acids exist in nature, some waxes also contain higher unsaturated fatty acids and hydroxy acids. These waxes are paraffin It has a close chemical structure, and is a solid crystallized or non-crystallized at room temperature, and its melting point is generally in the region of about 80 ° C. Typical waxes include candelilla wax, carnauba wax, rice wax, beeswax, whale mouth ゥ, and monsoon wax. These waxes may be mixed singly, or may be a wax to which a third component is added. The main components are ester compounds of higher fatty acids and higher alcohols, which have the chemical composition of wax. There are two types of oils: petroleum oils and synthetic oils. It is easy to understand that the mouth is a natural box.

Petroleum oils are hydrocarbons that are present in crude oil and are solid or semi-solid at room temperature, and are roughly classified into paraffin wax, microcrystalline wax, and petrolactam.

Paraffin wax is mainly composed of straight-chain saturated hydrocarbons having 20 to 36 carbon atoms, and contains a small amount of side-chain saturated hydrocarbons, naphthine and aromatic hydrocarbons, and has a molecular weight of 300 to 500 It is solid at room temperature. Microcrystalline wax is a somewhat complex compound having a molecular weight of 450-700 and a side chain in the main chain, which is larger than that of paraffin wax, and has a carbon number in the range of 31-50. . It is a solid at room temperature that contains a small amount of straight-chain saturated hydrocarbons, naphthine, aromatic hydrocarbons, etc. in addition to the main chain side-chain saturated hydrocarbons.

Petrolactam is a semi-solid wax at room temperature that contains a small amount of straight-chain saturated hydrocarbons, naphthine, aromatic hydrocarbons, etc., in addition to the main chain side-chain saturated hydrocarbons, similar to microcrystalline phosphorus wax. It is. Synthetic resins include petroleum-based synthetic resins, polyethylene-based resins, fissure-port-opened synthetic resins, and oil-based synthetic resins.

As a petroleum-based synthetic wax, there is montan wax. It has a melting point of about 85 ° C, and is a black-brown box obtained by extracting with organic solvent from lignite containing men. The crude monoxide oxide is commercially available as an oxide.

Polyethylene wax is produced by the polymerization of ethylene, but also by pyrolysis of general-purpose polyethylene. Natural wax has a molecular weight of 100 or less, whereas polyethylene wax has a molecular weight of 1

000 to 100 000.The difference in physical properties due to the difference in molecular weight and the difference in chemical structure, such as the continuous structure of the ethylene chain, make various properties o.

The mouth / box component (D) of the present invention may be composed of a single mouth / single box, but rather is used by being blended. Further, the wax component (D) is a compound having a strong paraffinic property, having a very strong hydrophobicity, and being solid at room temperature. Therefore, it has a property that it is hardly dissolved in the polyfunctional polyol component (A), the polyfunctional polyisocyanate component (B) and the plasticizer (C). Therefore, even when it is mixed with the two-component reaction-curable urethane resin liquid (F), it is hardly dissolved, and is in a state of swelling and floating in a liquid system. In such a state, when the two-component reaction-curable urethane resin liquid (F) is rapidly cured, it is embedded and contained as a solid in the cured resin.

The wax component (D) is used in an amount of 1 to 20% by weight based on the two-component reaction-curable urethane resin solution (F). More preferably, it is 5 to 10% by weight. If the content is less than 1% by weight, the effect of using the wax component (D) disappears. If the content exceeds 20% by weight, the fluidity of the two-component reaction-curable resin liquid (C) deteriorates, and the workability at the time of resin model production is impaired. In addition, the strength of the resin model itself decreases, and the possibility of cracking or breaking at the time of demolding increases. The melting point of the wax component (D) is 60 to 130 ° C. Preferably it is 60 to 120 ° C. When the melting point is 60 ° C or lower, the wax component (D) is melted by the heat generated by the curing of the two-component reaction curable urethane resin solution (F), and the particles of the wax component (D) are fused. It is inappropriate because it separates into the upper layer of the model. When the melting point is higher than 130 ° C., the molecular weight is increased, the melt viscosity is high, and the dewaxing is undesirably delayed.

The particles of the wax component (D) are in the form of particles with a maximum size of 5 mm or less. If it is larger than 5 mm, it will be difficult to flow into the thick part of the model less than 5 mm, and the uniform distribution of the mouth and lips components (D) in the model will be impaired. The wax component (D) is preferably 1 mm or less. The particles of the wax component (D) float in the two-part reaction-curable urethane resin liquid (F) in a partially swollen state on the surface. Therefore, the wax component (D) of the fine particles does not instantaneously float on the liquid surface. In the cured resin model, particles are dispersed in a state covered with the resin film. Therefore, when the resin begins to undergo thermal expansion-partial thermal decomposition and melting in the dewaxing and firing process, the wax and wax component (D) exudes from the resin model as a high-temperature and low-viscosity liquid. That is, it contributes as a leading component for improving the outflow performance.

The hollow resin balloon (E) is a resin bead having a hollow inside. Phenol resin balloons A acryl resin balloon is commercially available. The particle diameter of these hollow resin balloons (E) is about 10 to 100 μm, and the true specific gravity is 0.01 to 0.03. When such a light-weight hollow resin balloon (E) is mixed with a two-component reaction-curable urethane resin liquid (F), it tends to float on the liquid surface. On the other hand, since the fine particles of the wax component (D) are compounded, the hollow resin balloon (E) has to push up the fine particles of the wax-wax component (D) and float up. The ascent to the surface is slower than expected. The two-component reaction-curable urethane resin liquid (F) has a short pot life, causing a chemical reaction from the moment of mixing the two components, and the pot life is as short as 1 to 5 minutes. Since there is a rise in viscosity at this point, the intensive floating of the hollow resin balloon (E) on the liquid surface is prevented.

If the particle diameter of the hollow resin balloon (E) is 10 μm or less, the fluidity of the two-component reaction-curable urethane resin liquid (F) compounding system becomes poor, and the casting operation becomes difficult. When the particle size is 100 zm or more, the floating of the hollow resin balloon (E) particles in the two-component reaction-curable polyurethane resin liquid (F) compounding system is accelerated, and separation in the liquid is not preferred. The preferred particle size is between 20 and 80 microns.

As a result, the hollow resin balloon (E) is relatively uniformly dispersed in the cured resin model (H) mixed with the two-component reaction-curable urethane resin liquid (F). This means that gas was dispersed in the resin model (H) in a sealed state, and dewaxing and interspersed with unnecessary combustion components contributed greatly to dewaxing properties. It produces a contributing effect.

The compounding amount of the hollow resin balloon (E) is 0.001 to 1.0% by weight based on the two-component reaction-curable urethane resin liquid (F). When the amount is less than 0.001% by weight, the effect of greatly reducing the degassing property and flammability is reduced. If the content is more than 1.0% by weight, the resin mixture becomes rough and the fluidity becomes poor, so that smooth casting becomes difficult. Preferably, the compounding amount of the hollow resin balloon (E) is 0.03 to 0.10% by weight based on the two-component reaction-curable urethane resin liquid (F).

Polyfunctional polyol component (A), polyfunctional polyisocyanate component (B), plasticizer (C), wax wax component (D), and hollow resin balloon (E) If necessary, an inert organic compound having no active hydrogen may be added to the two-component reaction-curable urethane resin solution (F) composed of For example, organic solvents, antioxidants, coloring agents, curing accelerators, dispersants, modifiers, and the like. As the organic solvent, methyl acetate / ethyl acetate / butyl acetate / methyl ethyl ketone / methyl isobutyl ketone'toluene / xylene may be blended for the purpose of reducing the viscosity. As an antioxidant, a hindered phenol or a hindered amine may be blended for the purpose of preventing thermal deterioration and ultraviolet light deterioration. As a coloring agent, an organic dye may be blended for the purpose of aesthetic sense. Tertiary amine / a trace amount of zinc octylate-peptyltin laurate may be added as a curing accelerator. As a dispersant, an amide compound or a surfactant may be added. However, it is not preferable to mix inorganic substances that become ash after combustion.

Next, the refractory coating liquid (I) will be described in detail.

The refractory coating liquid (I) is a slurry-like liquid in which fine zirconium alumina is usually blended with colloidal silica ethyl silicate. As the binder used for the refractory coating liquid (I), ie, co-idal silica and ethyl silicate, has a usable life, it is particularly necessary to carefully control the pH of the liquid. is there. Colloidal silica and ethyl silicate are hardened by a dehydration reaction. When this is fired at a high temperature, it is further dehydrated and becomes ceramic by the Si—0—Si bond, resulting in a high hardness 鎵. Since ethyl silicate is used in an alcohol solvent system, alcohol is scattered during drying. Colloidal silica is water-based, and water is scattered when dried.錶 In the construction industry, due to the problem of environmental pollution, colloidal silicity, which does not splash alcohol, tends to be heavily used.

Next, the epoxy silicon (N) used in the present invention will be described in detail. explain.

Epoxysilicone (N) is a low-viscosity, sprayable liquid obtained by mixing bisphenol A type epoxy (J) with aminosilane (K) and diluting it with an organic solvent (L).

Bisphenol-type epoxy (J) is an epoxy having a molecular glycidyl group represented by the chemical structural formula shown in the following chemical formula 4, and includes bisphenol A-type epoxy and bisphenol F-type epoxy. Bisphenol A-type epoxy is commercially available under the trademark Epikoto 828 Epicoat 1001. Bisphenol type epoxy (J) is represented by the following chemical structural formula.

R

O H ^^-C- ^) -Q C H EC H C H s

o n = 1 to 1 0

R: H or CH a

Aminosilane (K) is commercially available as a silane coupling agent, and is a compound having an alkoxysilyl group and an amino group at the molecular terminal represented by the following chemical structural formula.

H ₂ N (CH ₂ ) p [NH (CH ₂ ) p] qS i (OR) nRm

p: 2-3

q: 0 ~ 1

n + m = 3

R: G aH2a + l

(a = l ~ 2) To be specific, aminopropyltriethoxysilane, N-(? aminoethyl) -1-aminopropyltrimethoxysilane, N-1 (? aminoethyl) -aminopropylmethyl Dimethoxysilane and the like.

The organic solvent (L) is preferably a diluting solvent for epoxy resins that does not impair the reaction between epoxy and amine. For example, ketone-based organic solvents as true solvents for dissolving epoxy resins, ester-based organic solvents, ether-based organic solvents as diluent solvents for dissolving and diluting epoxy resins with true solvents, aromatic organic solvents, alcohol-based solvents Organic solvents and the like.

Examples of the ketone organic solvent include methyl ethyl ketone and methyl isobutyl ketone. Examples of the ester-based organic solvent include methyl acetate-ethyl acetate / propyl acetate / butyl acetate. Examples of ether organic solvents include dioxane, ethylene glycol dimethyl ether and ethylene glycol dibutyl ether. As the aromatic organic solvent, toluene and xylene are typical. Alcohol organic solvents include methanol- Ethanol. Isopropyl alcohol and butyl alcohol 'Ethylene glycol monomethyl ether and the like. Since these organic solvents contain a trace amount of water, they are preferably used after being dehydrated as much as possible.

When the bisphenol-type epoxy (J) and the aminosilane (K) are mixed, the glycidyl group of the bisphenol-type epoxy (J) and the amino group of the aminosilane (K) undergo an addition reaction at room temperature to bond. The alkoxysilyl group of aminosilane causes a dealcoholization reaction with the moisture in the air and the OH group on the surface of the underlying refractory coating layer to form a film. The addition reaction between the glycidyl group and the amino group and the dealcohol condensation reaction between the alkoxysilyl group proceed smoothly at room temperature.

The blending ratio of bisphenol-type epoxy (J) and aminosilane (K) is determined by determining the blending weight such that aminosilane (K) is 1.5 to 2 moles per mole of bisphenol-type epoxy (J). Good.

The epoxy silicon (N) layer adheres firmly to the underlying primary and backup layers. The adhesion mechanism is that the alkoxysilyl group of aminosilane (K) undergoes a de-alcohol reaction with the Si—OH group on the surface of the underlying refractory coating layer, and the formation of a Si—0—Si bond occurs. Strong bonding with covalent bonds. Also, it is considered that the OH group generated by the addition reaction between the epoxy group and the amino group generates a hydrogen bond with Si—OH of the base refractory coating layer, and is strongly bonded.

In addition, it has a relatively heat-resistant chemical structure among resins, and is hardly thermally decomposed in a low-temperature region (100 to 200 ° C), contributing to an increase in type I strength. In the medium temperature range (300-500 ° C), it burns, so intensity intensity will disappear gradually. In the high temperature region (500-10000 ° C), the 銪 type is sintered and ceramicized, and the mirror-type strength reaches the maximum strength.低温 Low temperature range where the strength of mold strength is insufficient and cracks are likely to occur. Epoxy silicon (N) compensates for insufficient strength at 200 ° C) ο

In the case of dewaxing the resin model (H) of the present invention, it is necessary to adapt the optimum conditions suitable for the opening の of the wax model (H). In general, in the rotox precision manufacturing, the dewaxing temperature of the wax model is raised to 120 ° C, and dewaxed at 120 to 150 ° C for 1 to 2 hours. The temperature is raised to ~ 500 ° C. If this condition is applied as it is, the thermal expansion of the resin model and the generation of combustion gas due to thermal decomposition will cause the 錶 internal pressure to rapidly increase, causing the を to crack, and in some cases the 崩壊 to collapse. Become. It is considered that the reason for the cracks occurring when the mold dewaxes is that the internal stress increases when the mold 強度 strength is at a low level, and the mold 強度 strength does not withstand the internal stress.

As a result of examining the dewaxing and firing conditions suitable for the resin model of the present invention, preheating was performed for 2 to 8 hours in a low temperature range of 60 to 120 ° C, and 5 to 50% of the weight of the resin model was initially set. A step of dewaxing is provided, and the furnace temperature is gradually increased and heating is performed for 2 to 5 hours in a medium temperature range of 150 to 500 ° C, and a step of degassing and burning of the resin model is completed. It comprises a step of firing in a high temperature range of from 100 to 100 ° C. In other words, low-temperature dewaxing conditions that avoid rapid temperature rise are introduced because resin components that are difficult to dewax are mainly used.

By preheating at 60 to 120 ° C for 2 to 8 hours, the plasticizer (C), microphase separated in the resin component, oozes through the resin membrane to the interface between the resin and the mold. Seems to come. This is accumulated, and the plasticizer (C) starts flowing out of the gate through the inner surface of the mold. Furthermore, since the wax component (D) is at a temperature near or above its melting point, it has begun to soften and liquefy, exuding together with the plasticizer (C), or the plasticizer (C). Begins to flow out of the gate along the path that has flowed out. In the low temperature range of 60 to 120 ° C, the resin component is in a softened and degraded state, and pyrolysis that has generated gas has not yet occurred. Therefore, the inside of the mold is an internal pressure due to the thermal expansion of the resin component, and serves as a force for pushing out the plasticizer (C) and the wax component (D) to the gate. Therefore, the pressure inside the mold 錶 is reduced by the extrusion and outflow, so that the mold 耐え can withstand the internal pressure and the generation of cracks can be avoided.

When the temperature rises to 300 ° C. or higher, the resin component undergoes thermal decomposition, generating decomposition gas, while decomposing the main chain and side chains to lower the molecular weight, and the resin itself partially liquefies. Decomposed gas is generated inside the type III and is contained. As a result, the internal pressure of the mold increases, but if the passage through which the plasticizer (C) or wax component (D) escapes at 60 to 120 ° C is opened, the decomposition gas can be easily removed. Get out. It also serves as a force to push out the residual liquefied material to the gate, and when the residual liquefied material flows out of the gate, the decomposition gas is released out of the system, and the internal pressure of the mold decreases.樹脂 Inside the mold, the resin is thermally decomposed steadily, generating decomposition gas. With these phenomena, venting and combustion occur sequentially, and it is thought that the sudden increase in the internal pressure of mold 鎳 is considerably reduced. When the outlet ① and combustion are activated at the same time, a considerably large space is created between the mold 錶 and the resin model, and the flame is released and the residual liquefied material flows out. The constituent components of the two-component reaction-curable urethane resin liquid (F) used in the present invention are a balance between casting workability, curability, shape retention of the cured product, opening property, thermal decomposition, and flammability. It is designed to be a resin model with improved defects of the mouth model. When dewaxing a resin model composed of these constituents, there is a large point in that the temperature conditions for slowly and gradually dewaxing are set so as not to apply excessive stress to the mold. In addition, a structure in which an epoxy silicon layer is sandwiched between the refractory coating layers In the meantime, we increased the strength of type III in the low temperature range.

The composition of the resin model and the strength of the refractory coating material and the application of dewaxing conditions suitable for the resin model have been studied diligently from three directions, and a method of forming a mold without cracks in the dewaxing and firing processes. Heading, the present invention has been reached. Industrial applicability

As described above, a number of effects can be obtained by performing the precision structure using the mold for lost wax precision structure of the present invention. The effects are as follows.

We can manufacture thin-walled, complex-shaped products with sharp edges and ribs, which could not be achieved by conventional Lost-X precision manufacturing.

By adapting to titanium alloys, we can manufacture thin, complex-shaped titanium products with excellent dimensional accuracy, light weight, high hardness, high heat resistance, and high corrosion.

High-precision and lightweight lightweight mechanical parts for racing cars, aircraft jet engine parts, robot parts, and space development rocket parts.

In particular, it is possible to manufacture structural parts for the high-tech industry, and great effects are expected.

Claims

The scope of the claims

1. Consists of a polyfunctional polyol component (A), a polyfunctional polyisocyanate component (B), a plasticizer (C), a wax component (D), and a hollow resin balloon (E). A process of combining a liquid reaction-curable urethane resin liquid (F), casting it into a mold (G), curing it, and removing it from the mold to produce a resin model (H):

After the resin model (H) is immersed in the refractory coating liquid (I), the resin model (H) is pulled up and dried, and epoxy silicon (N) is applied to the surface, dried and cured to form a coating layer. The forming operation is repeated a plurality of times to produce a primary layer composed of a plurality of coating layers laminated on the surface of the resin model (H):

After the resin model (H) is immersed in the refractory coating solution (I), the surface is sprinkled with silver (M) and dried, and epoxy silicon (N) is applied and dried and cured. The operation of forming a thick coating layer by repeating a plurality of times to form a thick coating layer on the surface of the resin model (H):

A resin model (H) coated with a thick refractory coating multilayer consisting of the primary layer and the back-up layer is placed in a furnace with a gate down, and in a low temperature range of 60 to 120 ° C, Pre-heating for 2 to 8 hours to initially dewax 5 to 50% of the resin model weight:

The furnace temperature is gradually increased, and heating is performed for 2 to 5 hours in a medium temperature range of 150 to 500 ° C to exit the resin model and finish the combustion: and

Baking in a high temperature range of 500 to 1000 ° C. for 2 to 5 hours.

2. The average number of functional groups of the polyfunctional polyol component (A) is 2.8 or more, and the average number of functional groups of the polyfunctional polyisocyanate component (B) is 2. ° or more. 2. The method of claim 1, wherein 0/0 ^ 1 is in the range of 0.8 to 1.0.

3. The port according to claim 1, wherein the plasticizer (C) is phase-separated and micro-dispersed during the reaction curing of the two-component reaction-curable urethane resin liquid (F). Manufacturing method for molds for precision manufacturing.

4. The two-part reaction-curable urethane resin liquid (F)

-(CH ₂ CHO) n- R: H or CH ₃

I n: 1-5 0

R

4. A loss-to-truss precision manufacturing method using a resin model according to any one of claims 1 to 3, wherein the resin contains 2 to 20% by weight of a polyether resin represented by the following formula: Mold making method.

5. The wax component (D) is in the form of a powder having a melting point of 60 to 130 ° C and a maximum of 5 mm, and 3 to 30% by weight in the two-component reaction-curable urethane resin solution (F). The method for producing a mold for precision manufacturing of a lost-stroke structure according to any one of claims 1 to 4, wherein the mold is contained.

6. The method according to claim 1, wherein the epoxy silicon (N), the bisphenol compound (J), the aminosilane (K), and the organic solvent (L) are included. 6. The method for producing a mold for precision manufacturing of a lost tox according to any one of the items 5 to 5.

7. The particle diameter of the hollow resin balloon (E) is 10 to 100 μm, the true specific gravity is 0.01 to 0.03, and the two-part reaction hardening type urethane resin liquid ( 7. The mouth wax according to any one of claims 1 to 6, wherein the wax is incorporated in the composition (F) in an amount of 0.001 to 0.5% by weight. Manufacturing method of mold for precision manufacturing.