JP2003290871A - Burning-down resin pattern and precision casting method using this burning-down resin pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems as heating fuse-loss characteristic, high temperature burning characteristic and residual ash content in a resin pattern improving the disadvantage in a wax pattern. <P>SOLUTION: In a burning-down resin pattern used for a lost wax method, a resin liquid composition is formed by adding 1 to 30 wt.% plasticizer (D) into a two-liquid reaction hardening type urethane resin liquid (C) composed of a multi-functional polyol component (A) and a multi-functional polyisocyanate component (B), and further adding 1 to 20 wt.% wax component (E). The resin composition is hardened within 5 min of usable time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a precision casting method by the lost wax method. The present invention intends to fundamentally improve the defects of the wax model used in the lost wax method by using a resin model in a specific range.

[0002]

2. Description of the Related Art The entire precision casting method by the lost wax method as a conventional technique will be described.

The lost wax method is a method in which a molten wax component is poured into a mold for mass production of a wax model, cooled, and then demolded to produce a wax model having the same shape as a cast product, and the surface of the wax model is Harden with a refractory, heat to melt out the wax model, burn out at high temperature completely to make a hollow mold, pour molten alloy into this mold, cool and solidify the mold after crushing It has a manufacturing process of taking out a cast product.

More specifically, a wax model is manufactured by injection-molding this wax component in a mold. At this time, the injection temperature, the injection pressure, the injection pressure holding time, and the cooling demolding temperature are controlled to obtain a constant quality. Wax model is produced. The wax model manufactured in this way is stored in a constant temperature room at a constant temperature, and great care is taken to maintain dimensional accuracy. This wax model is assembled by brazing the wax model to a separately prepared sprue model. The entire assembled model is called a tree. Since the shape of this tree will be a sprue system as it is, many factors such as the properties of the molten metal, the size and shape of the casting, the casting conditions, and the cuttability from the tree will be taken into consideration in the design.

The tree thus produced is coated in layers by repeating dipping and drying in a coating slurry. The binder used in this coating slurry is colloidal silica, ethyl silicate, hybrid or the like. Refractory fine powder is mixed as a filler with these binders to form a slurry. The wax model is dipped in the slurry thus produced, pulled up, sprinkled with stucco grains and dried. Zircoside or molokite grains are used as the stucco grains. The coating operation is completed by repeating these operations several times.

Next, in the autoclave, 120-
The wax model is eluted from the mold at 150 ° C. This is called dewaxing. The dewaxed shell mold is fired by raising the temperature in stages in a high temperature firing furnace at 700-1000 ° C. in order to remove the adhered wax and incompletely burned carbon powder and enhance the strength of the mold. . The molten alloy is cast into the mold thus manufactured, and after cooling, the mold is disintegrated by a knockout machine, the cast product is taken out, the runners, coughs, etc. are cut and removed, and the adhered residual refractory is removed by blasting. Also, repairable parts are repaired by welding, finished with a grinder, and then heat-treated to obtain a cast alloy product.

Various researches and developments have been made on the model used in the above-mentioned lost wax 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 wax component is described in detail in the Foundry Handbook (edited by Japan Foundry Association). Further, recently, JP-A-5-38549 reports the effectiveness of a wax component in which a melamine powder is blended with the wax component. As described above, it is advantageous to use the wax model because the wax component retains the property of being melted at high temperature and easily dewaxed. As long as the wax model is used as the burned-out model, the mechanical strength and physical properties of the model itself are improved. Is limited.
Also, as a model, a method in which a synthetic resin and a wax model are laminated and combined has been reported. Japanese Unexamined Patent Publication No. 5-23791 discloses
A model in which a synthetic resin film is formed on the wax surface is disclosed. Japanese Unexamined Patent Publication No. 5-329174 discloses a tooth binding model made of hot-melt resin to form a model. further,
Japanese Patent Laid-Open No. 7-9084 discloses a model in which a lost wax stand is laminated on a photocurable resin sheet. Furthermore, JP-A-7-299542 discloses a model in which a wax / plastic material is applied to an embroidery model made of cotton thread or synthetic material. Further, JP-A-7-47443 discloses a model in which a photocurable resin model or a hot-melt resin laminated model is inserted into a mold, and lost wax is injection-molded. Further, Japanese Patent Laid-Open No. 2000-263186 discloses a model in which a lost wax stand is laminated on an ultraviolet curable resin model. As described above, synthetic resin has come to be used for a part or the whole of the model, which is mainly aimed at improving the shape retention of the wax model and simple model production. That is, it is a product in which the digitization of the molding method has been developed and the application of the photocurable resin or the thermoplastic resin to the molding has been advanced accordingly.

As a method most similar to the present invention, a precision casting method using a lost wax method as a wax model substitute for a model using a synthetic resin has been proposed.
-210755 is available. This is to make a reaction injection molding thermosetting polyurethane foam model, form a shell mold around the model, and dewax the model in the heating process,
A shell mold is hardened and a molten metal or molten alloy is cast. This is fundamentally different from the present invention which proposes a precision casting method using the lost wax method by using a foamed / non-foamed urethane model containing a plasticizer and a wax component as essential components as a wax model substitute.

On the other hand, a conventional technique of a material and a manufacturing method for producing a resin model will be described. There are various conventional techniques for producing a resin model. The basis is a method of manufacturing wood and plastic plate rods by cutting and bonding. Himekomatsu, a dried hoe tree with good dimensional accuracy, is favored in the wood mold industry for making cast models. In order to cancel the directionality of the wood and avoid distortion when making the model, a highly precise wooden model is manufactured by changing the directionality of the wood over time.

In the design model industry for producing plastic models, plate rods of Bakelite, acrylic, PP, vinyl chloride, etc. are produced by cutting and bonding. Recently, chemical wood, which is made by solidifying micro resin balloons with urethane resin and has excellent dimensional accuracy and machinability, is widely used.
Due to the rapid development of AD / CAM, we have received orders for model shapes using data rather than drawings, and have begun to make chemical wood models by cutting non-directional chemical wood with NC machines.

On the other hand, a stereolithography method in which a model shape is ordered by CAD data and a light ray controlled by computer is irradiated to a photocurable resin to manufacture a donut-shaped resin-cured disk, which is sequentially stacked to form a three-dimensional resin model. Has also become popular. The most prominent feature of this stereolithography method is that a hollow three-dimensional model can be manufactured without cutting.

Using one precision model thus created as a master model, a gypsum mold / resin mold is manufactured by gypsum inversion or resin inversion, and liquid resin is cast into the mold.
A plurality of resin models can be manufactured by curing and replicating the resin models. Liquid resins for casting include urethane resin, epoxy resin, unsaturated polyester resin,
Acrylic resin is used. Further, the resin material is selected in consideration of the required performance of the resin model.

Further, when it is necessary to manufacture a large amount of products, the resin model needs to be manufactured by a mass production manufacturing method instead of the above-described prototype model manufacturing method.
That is, it is an injection method in which the molten thermoplastic resin is exposed to a mold at high temperature and high pressure, cooled and solidified, and then demolded. Further, the RIM method in which a two-liquid reactive liquid resin is injected into a mold and cured while causing a polymerization reaction inside the mold is also a very effective method, and has already been industrialized as a short-term mass production method.

[0014]

As described above, when a precision cast product is manufactured by the lost wax method, the model is generally a wax model composed of a wax component. This is due to the fact that the wax component is easily melted away at high temperatures, and has the advantage of being excellent in the ability to burn in the mold high temperature firing step, but in recent years precision castings have become complicated structures, and Strict dimensional accuracy is being demanded, and there are cases where the wax model cannot handle this situation.

That is, the problems associated with these wax models are that the edges are difficult to come out, the thin ribs are hard to stand, the thin ribs are easily broken, and the thin parts must be demolded with great care when demolding, 1 mm or less. There is a technical limit to the production of a wax model having a too thin part. In addition, the wax model produced has problems such as being easily scratched, having poor dimensional accuracy, and being damaged by a drop impact during carrying because the surface hardness is low. Since it is apt to occur, it has a problem that it must be stored in a temperature-controlled room. Especially in the summer, when you move the wax model, you must be very careful. Furthermore, the wax component is a relatively low molecular weight organic substance, and has a problem of softening at about 80 ° C. Thus, the problems of the wax model concentrate on the problems caused by the wax component. In order to improve the problems caused by the wax component as described above, improvement studies have been made by changing the composition of the wax component, but the wax component is a low melting point organic substance that dissolves at a temperature slightly higher than room temperature, but at room temperature The current situation is that the fundamental problems have not been solved because of crystallization and solidification.

From the above, the inventors of the present invention have earnestly studied the resin composition for the purpose of improving the defects of the wax model, the resin composition for clearing the heating and melting runoff performance, the high temperature combustion performance, and the residual ash content. As a result of repeated stacking, they have found that a resin model composed of a resin liquid composition within a limited range is effective as a wax model substitute, and completed the present invention.

[0017]

SUMMARY OF THE INVENTION Therefore, the present invention provides
In the burned-off resin model used in the lost wax method,
A two-component reaction-curable urethane resin liquid (C) comprising a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B) containing 1 to 30% by weight of a plasticizer (D) and a wax wax. 1 to 20% by weight of component (E) is contained to form a resin liquid composition, and the resin liquid composition is cured within a pot life of 5 minutes (claim 1). Particularly, the pot life is preferably 1 to 2 minutes.

In the two-component reaction curing type urethane resin liquid, the polyfunctional polyol component (A) has an average number of functional groups of 2.8 or more, and the polyfunctional polyisocyanate component (B) has 2.0. It is desirable to have the above average number of functional groups and NCO / OH to be 0.7 to 1.0 (claim 2).

Further, it is desirable that the plasticizer (D) be phase-separated and microdispersed when the two-component reaction-curable urethane resin liquid (C) is cured by reaction.

Furthermore, it is desirable that the two-component reaction curing type urethane resin liquid (C) contains 2 to 25% by weight of a polyether chain represented by the following chemical structural formula (claim 4).

[0021]

[Chemical 2]

The wax component (E) is
It is desirable that the particle size be in a granular, scaly, or lumpy shape and fit in about 1 cm ³ (claim 5).

Furthermore, it is desirable that 0.01 to 1.0% by weight of water (F) be contained in the two-component reaction-curable urethane resin liquid (C) to be water-foamed (claim 6). It is desirable that the liquid reaction curable urethane resin liquid (C) contains 10 to 25% by weight of the organic solvent (G).

Furthermore, it is desirable that the two-component reaction-curing urethane resin liquid (C) contains 1 to 10% of fine particles (H) of natural polymer waste (claim 8).

Further, it is desirable to carry out precision manufacturing by the lost wax method using the above burned resin model.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION The component composition of the two-component reaction-curable urethane resin liquid (C) used in the present invention will be described first. The skeleton of the two-component reaction-curable urethane resin liquid (C) is composed of two liquids of a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B). It is initiated and cured by heat. The plasticizer (D) and the wax component (E) contained in the two-component reaction curing type urethane resin liquid (C) are blended with either the polyfunctional polyol component (A) or the polyfunctional polyisocyanate component (B). It may be added, or both may be mixed. Further, since the water content (F) causes a chemical reaction with the polyfunctional isocyanate component (B), it is added to the polyfunctional polyol component (A) in advance. Since the natural cellulosic waste (H) causes a chemical reaction with the polyisocyanate component (B), it is mixed in advance with the polyfunctional polyol component (A). The organic solvent (G) may be added to either the polyfunctional polyol component (A) or the polyfunctional polyisocyanate component (B), or may be added to both.

Next, each component will be described.

As the polyfunctional polyol component (A), there are low molecular weight polyols, polyether polyols, amine polyols, polyester polyols, acrylic polyols, polybutadiene polyols and the like, and as a special one, castor oil and its derivatives are used. It

Examples of the low molecular weight polyol include ethylene glycol / propylene glycol / 1-4 butanediol / glycerin / trimethylolpropane / pentaerythritol.

Examples of the polyether polyol include polyether polyols having various molecular weights obtained by adding ethylene oxide or propylene oxide to the above low molecular weight polyol. Polyether polyol is ethylene oxide single addition, propylene oxide single addition,
The terminal hydroxyl group becomes primary or secondary by various addition methods such as mixed addition and sequential addition. As a result, various kinds of polyether polyols having different reactivity of terminal hydroxyl groups and different added chains having different hydrophilicity / hydrophobicity depending on ethylene oxide and propylene oxide. Also, TH
There is also a polytetramethylene ether glycol obtained by cationic polymerization of F, which is usually called PTMG.

The amine polyol is a low molecular amine such as ammonia / ethylenediamine or polyethylenepolyamine to which ethylene oxide or propylene oxide is added. As a result, amine pol
It is a polyol having an effect of promoting the reactivity of isocyanate by containing a tertiary nitrogen in the molecule. The amine polyol using ammonia as a starter is trifunctional, the amine polyol using ethylenediamine as a starter is tetrafunctional, and when polyethylenepolyamine is used as a starter, it is polyfunctional or higher.
These are the components essential to the present invention that perform rapid curing.

As the polyester polyol, there is a condensation type polyester polyol in which a dibasic acid and a low molecular weight polyol are esterified to form a hydroxyl group at the molecular end. A wide variety of polyester polyols can be obtained by selectively adjusting the types of dibasic acid and low molecular weight diol / triol, adjusting the molecular weight, and using a small amount of multifunctional low molecular weight polyol. Adipic acid is often used as the dibasic acid used in the condensation type polyester polyol. As the low molecular weight diol, ethylene glycol, propylene glycol, 1.
Glycerin as a triol, such as 4-butanediol,
Examples include trimethylolpropane and their low alkylene oxide adducts. As for the ring-opening polymerization type polyester polyol of ε-caprolactam, the number of functional groups and the molecular weight are adjusted by adjusting the kind and amount of the ring-opening polymerization initiator used. By adding alkylene oxide to these, some have a polyester chain and a polyether chain, and some have very multiplicity. There is also a carbonate diol obtained by ring-opening ethylene carbonate.

The acrylic polyol is a polymer obtained by polymerizing methyl acrylate or methyl methacrylate with an acrylic monomer having a terminal hydroxyl group, and is an acrylic oligomer having a plurality of hydroxyl groups in the acrylic chain.
Various acrylic polyols formed by selecting the type of acrylic monomer and adjusting the molecular weight are already commercially available. The resin liquid obtained by raising the degree of polymerization to a level at which a film is formed and polymerizing it and dissolving it in an organic solvent is slightly crosslinked by the aliphatic polyisocyanate, resulting in a coating having excellent weather resistance.

Polybutadiene polyol is a copolymer of butadiene having a hydroxyl group at the terminal and a compound having a double bond. It is a relatively strong polyol.

A urethane-modified polyol having terminal hydroxyl groups may be formed by joining these polyfunctional polyols with polyisocyanate. In this case, the molecular weight is slightly increased due to oligomerization due to urethane modification,
There is a strong tendency for the viscosity to increase. Therefore, it is preferable to use a urethane-modified polyol as a part of the polyfunctional polyol.

These polyfunctional polyols may be used alone or in combination of two or more. Generally, in order to satisfy many requirements for a purpose, a molecular structure is designed by mixing and using various polyfunctional polyol components in necessary amounts. These polyfunctional polyol components (A) have an active hydroxyl group at the molecular end, and the reactivity with isocyanate varies depending on the type of the hydroxyl group at the molecular end.

Particularly, the polyether polyol and the polyester polyol have a strong affinity for water and contain a small amount of water. This trace amount of water does not cause any inconvenience when used in water-foamed urethane. However, in the case of using non-foamed urethane, it is necessary to firmly reduce and control the trace amount of water. Therefore, the polyfunctional polyol component (A) is produced through a heating mixing dehydration step.

The polyfunctional polyisocyanate component (B) is a compound containing two or more isocyanate groups in one molecule, and the polyol component is one containing two or more hydroxyl groups in one molecule. . The isocyanate group is a highly reactive functional group and reacts with a hydroxyl group having active hydrogen, an amino group or a thiol group. Since amino groups and thiol groups react instantaneously, they are limited to isocyanate components that are poorly reactive and aromatic amines that are poorly reactive, but their combinations are often used because they react too quickly. Absent.

As the polyisocyanate component, there are aromatic polyisocyanate, aliphatic polyisocyanate and alicyclic polyisocyanate. Typical aromatic polyisocyanates are tolylene diisocyanate and diphenylmethane diisocyanate. Tolylene diisocyanate is obtained as a mixture of various isomers due to a chemical reaction during production, and industrially, TDI-100 (2,4-TDI 100 is used depending on a mixing ratio of 2,4-isomer and 2,6-isomer).
%), TDI-80 (2,4-TDI 80% 2,6-
TDI 20%), TDI-65 (2,4-TDI 6
5% 2,6-TDI 35%) is commercially available. Similarly, diphenylmethane diisocyanate is obtained as a mixture of various isomers due to the chemical reaction during production, and industrially, there are pure MDI and polymeric MDI. Pure MDI is a binuclear body, polymeric MDI is a polynuclear body, and pure MDI is isolated by distillation, leaving the polymeric MDI as a bottom residue. Since this polymer MDI has different numbers of polynuclear bodies under the manufacturing conditions, various polymer M
There is DI, and it is marketed by each manufacturer. Further, naphthalene diisocyanate having an isocyanate group in the naphthalene nucleus and tolidine diisocyanate can be mentioned. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and lysine diisocyanate. Examples of the alicyclic polyisocyanate include hydrogenated xylylene diisocyanate obtained by hydrogenating xylylene diisocyanate and hydrogenated MDI obtained by hydrogenating MDI.

Since polyisocyanates are generally highly reactive, and particularly volatile polyisocyanates are highly toxic, they are used in various modifications. These include urethane modification, dimerization, trimerization, polycarbidiimidization, urea modification, prepolymerization, blocking and the like. These are self-condensed by utilizing the high reactivity of the isocyanate group, or jointed via the active ingredient,
An isocyanate group remains at the terminal.

The specific range of the present invention regarding the two-component reaction-curable urethane resin liquid (C) containing the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) as resin components will be described.

A two-component reaction-curable urethane resin liquid (C) containing a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B) as resin components has two polyether chains represented by the following chemical structural formulas. It contains -20% by weight.

[0043]

[Chemical 3]

When a polyether is used as the polyfunctional polyol component (A), the polyether chain is introduced. When a polyester polyol is used, if it is an ester of polyether, it means that a polyether chain has been introduced. If the polyfunctional polyisocyanate component (B) is a polyether-terminated terminal isocyanate, a so-called quasi prepolymer, it means that a polyether chain has been introduced. This polyether chain is the soft component of the urethane resin, especially the polyether chain derived from propylene oxide is very soft. The fact that it is very soft has the property that when it is heated to a high temperature in the dewaxing / firing process, it undergoes thermal decomposition, and liquefaction, outflow, and combustion easily occur due to thermal decomposition. In the present invention, this characteristic is skillfully exhibited by containing a polyether chain in an amount of 2 to 25% by weight. This effect diminishes when the content of polyether chains falls below 2% by weight. When the content of the polyether chain is 20% by weight or more, the soft component becomes too much and the cured product becomes soft, and the hardness required for the model cannot be maintained. Therefore, the more preferable polyether chain content is 5-
It is 20% by weight.

The compounding amounts of the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) are calculated by calculating the number of NCO groups and the number of OH groups.
It is designed so that the ratio NCO / OH of the number of O groups and the number of OH groups is around 1.0. NCO / OH for urethane foam
Is designed in an isocyanate excess region of about 1.0 to 1.1. NCO / OH = 1.0 is a design in which the number of isocyanate groups and the number of hydroxyl groups are the same and the reaction is completed properly. In other words, it is the region that exhibits the highest strength. In the present invention, NCO / OH = 0.7 to 1.0 and NC
It is set in the O-deficient area. Normally, the molecular design of urethane is not performed in such an NCO-deficient region. The reason why the molecule can be designed in such an abnormal NCO / OH region in the present invention is that the polyisocyanate component has an average number of functional groups of 2.1 or more and the polyol component has an average number of functional groups of 3.0 or more. By NCO
This is because a three-dimensional mesh structure can be obtained even in the region where / OH is 1.0 or less. In this state, the NCO group is insufficient and the OH group is excessive, but since the monomer used is polyfunctional, the monomer connection can be completed and the main chain can be formed without complete reaction of the functional group. The OH group having no excess reaction partner terminates the reaction with the OH group in the main chain.
For this reason, it is considered that the keep of hydrophilicity is increased, and as a result, the plasticizer having strong hydrophobicity can be phase-separated and micro-dispersed.

As a result, NCO / OH = 0.7-
It is 1.0, preferably 0.8 to 0.9. NCO / O
When H is 0.7 or less, the isocyanate group becomes significantly insufficient, and a three-dimensional network structure cannot be obtained after reaction curing,
It causes an extreme decrease in hardness, and finally becomes softer as it becomes difficult to maintain the shape. On the other hand, NCO / OH is 1.0
In the case of the above, the isocyanate groups become excessive, and unreacted isocyanate groups remain even after the demolding time comes, resulting in an unfavorable phenomenon that a predetermined hardness does not appear or color unevenness occurs on the surface of the cured product.

The catalyst for promoting the chemical reaction between the polyfunctional polyol component (A) and the polyfunctional polyisocyanate component (B) includes a metal catalyst and an amine catalyst. Examples of the metal catalyst include zinc octylate / lead octylate, dibutyltin dilaurate, and dibutyltin diacetate. As the amine catalyst, triethylenediamine, NN-
Dimethylpiperazine, N-methylmorpholine and the like can be mentioned. These catalysts are usually added in 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, the catalyst is added to the polyfunctional polyol component (A) so that the usable time, that is, the usable time is within 5 minutes. If the pot life is 5 minutes or more, the curing and demolding time will be 5 hours or more, which will be a problem in producing a resin model. If the pot life is less than 1 minute, the reaction viscosity will increase rapidly and it will be difficult to mix and cast the two liquids. Therefore, the pot life is preferably 1 to 2 minutes.

Next, the plasticizer (D) used in the present invention
Will be described.

The plasticizer (D) used in the present invention is a compound having no functional group that causes a chemical reaction and negligible inactive volatility, and is liquid at room temperature. Examples of the plasticizer (D) include ester plasticizers, ether plasticizers, and ester / ether plasticizers. Specifically, ester-based plasticizers include dioctyl adipate (DOA),
Dioctyl phthalate (DOP) and dibutyl phthalate (DBP) are typical. In addition, benzyl acetate, butyl benzoate, octyl benzoate, isopentyl benzoate, ethylene glycol benzoic acid diester, polyethylene glycol benzoic acid diester, propylene glycol benzoic acid diester, polypropylene glycol benzoic acid diester, ethylene glycol dioleate,
Examples thereof include polyethylene glycol diolate, propylene glycol diolate, and polypropylene glycol diolate. As the ether plasticizer, ethylene glycol dibutyl ether, ethylene glycol diphenyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl butyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol dimethyl ether, triethylene Examples thereof include glycol diethyl ether, troethylene glycol dibutyl ether, tetraethylene glycol dimethyl ether, and tetraethylene glycol diethyl ether. Examples of the ether ester type include ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethiten glycol monophenyl ether acetate and the like.

The amount of the plasticizer (D) used is 2 to 20% by weight based on the two-component reaction curing type urethane resin liquid (C). When the amount of the plasticizer (D) used is as high as 20% by weight or more, the plasticizer (D) bleeds to the surface of the resin model, causing stickiness and tack. Further, when the amount of the plasticizer (D) used is 2% by weight or less, it is difficult for the plasticizer (D) to flow out at the time of resin pyrolysis melt flow loss combustion in the dewaxing / firing process. This is because the plasticizer (D) is a liquid having a high viscosity at room temperature, but has a low viscosity that easily flows out at a high temperature. In order to exert such an effect strongly, it is desired that the plasticizer (D) be contained as much as possible. Usually, when a large amount of a plasticizer is contained in the resin component, as described above, the plasticizer bleeds to the surface of the cured product, and tack or stickiness is generated on the surface. Therefore, as a result of diligent studies to make the content of the plasticizer (D) as high as possible, as a result, the plasticizer (D) is phase-separated from the cured resin and rapidly cured within a usable time of 5 minutes. The inventors have found that it is effective to have a microscopically confined state in a network structure, and have completed the present invention.

Such a phase-separated micro-dispersed structure can be expressed as a state in which the plasticizer (D) is contained in the honeycomb-shaped cured resin. In addition, it can be said that the honeycomb-shaped cured resin has a structure having excellent strength properties, and has a three-dimensional structure in which the plasticizer (D) is carefully stored in the honeycomb and is not released to the outside. As a result, even if the plasticizer (D) is contained in a relatively high amount, it does not ooze out onto the surface of the cured product and cause tacking. When the phase-separated micro-dispersed structure is not used, the plasticizer is dissolved in the cured resin, and when it reaches the saturated state or more, the plasticizer oozes out on the surface of the cured product, and tack occurs. It tends to occur. Such a phase-separated microdispersion structure has been confirmed by an electron microscope. In order to promote the phase-separated micro-dispersed structure, it is necessary to perform rapid curing within 5 minutes of the pot life. Preferably within 3 minutes,
It is especially 1 to 2 minutes. When the pot life is 5 minutes or more, it becomes difficult to complete the phase-separated microdispersion, and it takes more than one day to release the mold during model production, which reduces the speed of model production.

The plasticizer (D) is required to be in a uniformly dissolved state when it exists as the two-component reaction-curable resin liquid (C), and phase separation micro-dispersion is promoted from the cured resin at the reaction-curing stage. At the time of completion of the reaction curing, the microdispersed plasticizer is contained and bleeding to the surface is prevented. The composition is constructed on the delicate balance. That is, it is necessary to design in a region where the balance between the hydrophilicity and the hydrophobicity of the plasticizer (D) and the reaction curable resin is well adjusted. Therefore, the alkylene oxide chain is effective as the hydrophilic segment, and the hydrocarbon chain is effective as the hydrophobic segment. These hydrophilic segment / hydrophobic segment are determined by the selection of the raw material monomer to be used. The balance between the hydrophilicity and the hydrophobicity needs to be designed to be separated to some extent. When the ethylene oxide chain is frequently used in the two-component reaction-curable resin liquid (C), the hydrophilicity becomes strong, and when the propylene oxide chain is used, the hydrophilicity becomes weaker than that of the ethylene oxide chain. When the ethylene oxide chain and the propylene oxide chain are reduced, the two-component reaction curable resin liquid (C) having strong hydrophobicity is obtained. By adjusting these, hydrophilicity and hydrophobicity can be adjusted within a certain range. Further, by adjusting the type and amount of the plasticizer (D) used, the hydrophilicity and hydrophobicity of the plasticizer (D) itself can be adjusted within a certain range. For example, when the end is an alkyl ether, methyl ether
The hydrophobicity increases as it changes from ethyl ether / butyl ether / phenyl ether. In this way, the chemical structure and the usage amount of the plasticizer (D) are changed, and the chemical structure and the usage amount of the two-component reaction curable resin liquid (B) are changed to set the region range for phase-separation microdispersion. By such a method, the plasticizer (D) is made relatively hydrophobic,
Further, when the resin component is set to have relatively strong hydrophilicity, phase separation micro dispersion is well established.

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

The wax component is a compound having no functional group that causes a chemical reaction and negligible inactive volatility, and is a crystalline solid at room temperature. The wax component (E) includes naturally occurring natural waxes and synthetically obtained waxes. As a natural wax, there are candles that are familiar to us. The chemical composition of the natural wax component is an ester composed of higher fatty acid and higher alcohol, and is called wax ester. The higher fatty acids and higher alcohols mainly have 16 or more carbon atoms. Since it is an ester compound, some acid value remains. That is, free fatty acids remain. In addition, since many saturated and unsaturated higher fatty acids exist in nature, some waxes also contain higher unsaturated fatty acids and hydroxy acids.
These waxes have a chemical structure close to that of paraffin, are solids crystallized or non-crystallized at room temperature, and their melting points are generally around 80 ° C. Typical waxes include candelilla wax, carnauba wax, rice wax, dense wax,
Examples thereof include whale wax, montan wax, lanolin wax auricuri wax, alfa wax, cork fiber wax, sugar cane wax, wood wax, sumac wax, microlostarine wax, and ground wax. As synthetic wax, polyethylene wax, Fisher-T
Wax obtained by topsch synthesis, waxy copolymer and ester thereof, wax obtained by catalytic hydrogenation of animal or vegetable oil or dietary oil having C8-C32 linear or branched fatty chain, and silicone wax , Fluorine-containing wax, and the like. These wax / wax components may be used alone or as a mixture, or may be a wax component or wax component to which a third component is added. The wax component (E) has a strong property as paraffin or olefin, is extremely hydrophobic, and is solid at room temperature. Therefore, it is difficult to dissolve in the polyfunctional polyol component (A), the polyfunctional polyisocyanate component (B) and the plasticizer (D). Therefore, even if it is blended with the two-component reaction-curable urethane resin liquid (C), it is difficult to be dissolved and it is in a state of floating in the liquid system. In such a state, the two-component reaction-curable urethane resin liquid (C) is rapidly cured, and as a result, it is contained as a solid in the resin having a three-dimensional network structure. Therefore, the resin model of the present invention is characterized in that the wax model is not directly exposed on the surface of the resin model, so that all the defects of the wax model are avoided. The wax / wax component (E) has a great effect of accelerating the outflow of the resin decomposed product "softened / pyrolyzed / melted" in the dewaxing / firing process by heating.

The wax component (E) is 1 to 20% by weight based on the two-component reaction-curable urethane resin liquid (C).
Is what is used. If the amount used is less than 1% by weight,
The dewaxing effect of using the wax component (E) disappears. When it is 20% by weight or more, the fluidity of the two-component reaction-curable resin liquid (C) deteriorates, and the workability during resin model production is impaired. In addition, the strength of the resin model itself decreases, and the possibility of cracking or breaking during mold release increases. Therefore, it is preferably 5 to 20% by weight, and more preferably 10 to 15% by weight.

This wax component (E) is 1 cm
It is in the form of particles, scales, or lumps that fit in the cube of ³ . The particles or lumps may be beads, lump sugar, or a slightly deformed shape. In other words, it is not limited to true balls or honest prisms. The size is such that it fits in a cube of 1 cm ³ . Preferably, the diameter is 1 mm (approximately 0.
8 mm ³ ) or less. Naturally, the wax component is less likely to flow into the thin portion of the model having a thickness of 1 mm or less. Therefore, the uniform distribution of the wax / wax component (E) in the model is impaired, but the shape retention as a model, the dimensional accuracy, the decomposition melt flow-out property at the time of heating, and the combustion decomposition residual ash content at high temperature are It is sufficient if the number of molds and precision casting can be implemented. Naturally, this wax component easily flows into the thick portion of 1 mm or more of the model. It is said that the uncured resin liquid also easily flows in, and as a result, the model can be released from the mold, and the resin component should be spread throughout the model. In a sense, it is convenient that a large amount of the wax component (E) flows into the thick portion of the model. In other words, the thick part is dewaxed.
Melt outflow decomposition combustion tends to be delayed in the firing process. If a relatively large amount of wax / wax component (E) flows into this part and is fixed by a hardened resin, a great effect is exerted in the dewaxing / firing process, which assists melt-out decomposition decomposition combustion well. It will be.

Next, the water (F) used in the present invention will be described.

Moisture (F) is H ₂ O. Moisture (F) includes intentionally blended water, a trace amount of water usually mixed into a chemical raw material in the manufacturing process, and water absorbed by the raw material itself from the air. Here, the water content (F) in the present invention includes all of them. The reason for using the water content (F) is to use carbon dioxide gas generated by a chemical reaction with a polyfunctional polyisocyanate as a foaming agent, that is, to introduce a urethane water foaming technique. As a result, the resin model is a foam containing a plasticizer (D), a wax component (E), and bubbles. As a result, within the limited range in which foaming is adjusted, such a resin model itself, which is a foam, maintains a firm shape-retaining property, and exerts great effectiveness in thermal melting decomposition outflow combustion in the dewaxing / firing process. To do.

The main factor that determines the expansion ratio is the amount of water (F), and the sub-factors are the adsorbed water on the mold surface, the temperature and humidity of the outside air, and the like. The amount of water (F) is 0.01 to 1.0% by weight based on the two-component reaction-curable urethane resin liquid (C). Preferably 0.03 to 0.5% by weight
Is. More preferably, it is 0.08 to 0.15% by weight. When the water content (F) is 1.0% by weight or more, a large amount of air bubbles are concentrated on the resin surface, the skin layer on the model surface becomes thin, and the skin layer is destroyed during demolding, and the air bubbles appear on the model surface in a concave state. As a result, the model surface becomes inconvenient.
That is, it is necessary to control the level of fine foaming. In the foamed urethane, a foam stabilizer is used to make the sizes of the bubbles uniform. In the present invention, of course, it is important to add a foam stabilizer to make the sizes of the bubbles uniform.

The water content (F) is usually added to the polyfunctional polyol component (A). This polyfunctional polyol component (A) is controlled by blending water and uniformly mixing it, and measuring a trace amount of water by the Karl Fischer method. When blended with the polyfunctional polyol component (A), water alone may be used, or there is no particular limitation as long as the component containing water does not cause abnormalities in model production. For example,
Examples thereof include a surfactant aqueous solution, a dye aqueous solution, an aqueous glue, and a resin aqueous solution.

The aqueous surfactant solution is an aqueous solution of an anionic surfactant, a cationic surfactant, a nonionic surfactant, a zwitterionic surfactant, or a polymer surfactant. However, the concentration of the aqueous solution is not particularly limited. That is, it is a liquid detergent containing a large amount of water, a solid detergent containing a small amount of water, or a powder detergent. These addition methods are to be added to the polyfunctional polyol component (A). This may be one that is uniformly dissolved in the polyfunctional polyol component (A), or may be in a dispersed and suspended state.

The surface active agent generally comprises a hydrophobic group which is a long chain alkyl group and a hydrophilic group which is easily dissolved in water. Since the highly hydrophobic plasticizer component (D) and wax wax component (E) are present in the compounding system, the surfactant is considered to be oriented in these highly hydrophobic compounds.

The aqueous dye solution is an aqueous solution of a dye having a hydrophilic group, and the aqueous glue is a kind of polymer surfactant and is a cellulose-based polymer aqueous solution.

The resin aqueous solution is an aqueous solution of a highly hydrophilic resin, and is typically vinyl acetate, EVA or the like.

When water-foaming in this way, a foam stabilizer is used to make the size of the bubbles as uniform as possible. The foam stabilizer is a kind of surfactant, and is generally of the type in which alkylene oxide is added to silicon. By adding a foam stabilizer and water-foaming the foam, it is possible to obtain a foam in which bubbles of the same size are relatively uniformly scattered in the model. In this case, the strength of the model decreases, but the dewaxing process
Since the dewaxing component and the calcining component are greatly reduced in the calcining process, a great advantage is realized. This is because there is no strict requirement for the strength of the model, and it is sufficient that the model can be smoothly demolded when demolding. Also, the strength of the model after demolding should be a level that can be carried.
Furthermore, it is sufficient that the change in shape is extremely small during storage at room temperature. Furthermore, at the time of fireproof coating, it is sufficient that the strength to withstand the coating work is maintained. From the above, since high strength is not required, the resin model of the present invention containing a plasticizer and a wax component is sufficient.

Next, the organic solvent (G) used in the present invention will be described.

As the organic solvent (G), an inert organic solvent which does not chemically react with isocyanate is selected. Inert organic solvents include aromatic organic solvents, ester organic solvents, ether organic solvents, aliphatic organic solvents,
There are chlorine-based organic solvents. The performance required of the organic solvent (G) is to dissolve the polyfunctional polyether (A), the polyfunctional polyisocyanate (B) and the plasticizer (D), the odor is mild, and the poisonous gas during combustion. It does not occur, and it is economical. The organic solvent (G) satisfying such required performance is preferably selected from aromatic organic solvents such as toluene and xylene.

The organic solvent (G) is liable to become a gas in the stage of the exothermic gelation of the two-component reaction-curable resin liquid (C), which has the effect of promoting the role of a foaming agent. In addition, the organic solvent (G) is in a state of being somewhat trapped inside the model after curing and demolding. If anything, the organic solvent (G) remains inside the thick-walled portion where the wall-thickness is 1 mm or more, which is difficult to burn, and the effect of promoting combustion during the dewaxing / sintering step is great. Further, the effect of lowering the resin viscosity and improving workability in model making is very large.

Next, the fine particles (H) of natural polymer waste used in the present invention will be described.

The fine particles (H) of natural polymer waste are
It is a fine piece of paper waste, wood waste, textile waste. The fine pieces of paper waste include fine pieces of newspaper, advertising paper, office copy paper, wrapping paper, cardboard and the like. As fine pieces of wood waste,
Examples include waste wood for construction, waste wood for civil engineering, furniture waste materials, wood between trees, dead grass of plants, and fine pieces of rice husks. The waste of textile clothing includes fine pieces of cotton clothing, linen clothing and wool clothing. For example, in the case of papers, disposable office paper is shredded and shredded, in the case of woods, sawdust produced by dismantling, crushing, and cutting, and in the case of textiles, it is made into single fibers. It is crushed and cut fiber waste. It is preferable to miniaturize various shapes having a length of 1 mm or less.

Fine pieces (H) of these natural polymer wastes
Is preferably blended with the polyfunctional polyol component (A). Since the specific gravity of the fine particles (H) of the natural polymer waste is close to that of the polyfunctional polyol component (A), sedimentation /
Since it hardly floats, it floats in the liquid of the fine particles (H) of natural polymer waste, and it is easy to relatively uniformly disperse them by mixing. When the fine particles (H) of the natural polymer waste are mixed in the liquid of the polyfunctional polyol component (A), the air contained in the fine particles (H) of the natural polymer waste is used. If it is difficult to mix and disperse and float, degassing under reduced pressure will remove air and facilitate mixing and dispersion.

The fine particles (H) of natural polymer waste are generally hydrophilic and thus contain more or less moisture. Therefore, when the fine particles (H) of the natural polymer waste are mixed and dispersed in the polyfunctional polyol component (A), the water contained in the fine particles (H) of the natural polymer waste is brought in. Thus, the amount of water in the polyfunctional polyol component (A) will increase. Therefore, it is necessary to control the water content of the polyfunctional polyol component (A) in consideration of the water content brought in by the mixing amount of the fine particles (H) of the natural polymer waste.

To the two-component reaction-curable resin liquid (C), a regulator / stabilizer / colorant / flammable filler / diluting solvent for each component is added. As the stabilizer, hindered phenol-based / hindered amine-based antioxidants are used. Organic dyes and carbon powders are effective colorants. The pigment is not preferable because it remains as ash in the firing process. Addition of flame retardants should be avoided. As flammable filler, hollow balloon or and carbon powder 1-10%
It is effective to contain it. What is a hollow resin balloon?
True specific gravity 0.15 to 0.50 g / cc, particle diameter 15 to 10
UCAR Phenoli, a lightweight differential of 0 μm
c Microballoon (manufactured by Union Carbide Co.) or Matsumoto Microsphere (manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.). The inclusion of such hollow resin balloons results in embedding air in the resin model, which promotes decomposition, outflow, and combustion in the dewaxing process and firing process, and has the effect of reducing residual ash content. . The content of the hollow resin balloon is 0.1 to 10% by weight based on the resin model. When it is 10% by weight or more, the reaction curable resin liquid (B) becomes rough and it becomes difficult to obtain smooth fluidity. Therefore, preferably 3 to 8% by weight
Is.

The present invention pursues what kind of resin composition is most suitable for a burned model used for precision casting, and proposes that a resin composition within a limited range is effective as a burned model. Insufficient strength, which is a drawback of the wax model, is definitely improved by using a resin model. If the resin model is not manufactured quickly, it will not be economical. From the beginning, resin models do not lead to mass production, so it is important for industrialization to be able to quickly produce resin models of other types in small quantities. Therefore, instead of an injection method using a mold / thermoplastic resin, a study was conducted on the resin composition as a burnout model in the area of a reaction-curing resin that rapidly cures.

On the other hand, when the hardened resin is very hard, there is a problem in that the melting, decomposition, flow and combustion are delayed during heating and heating, and the expansion of the resin causes the mold to crack and break. Therefore, it is necessary that the entire cured resin model is quickly softened, and the expansion stress of the resin is dispersed in the gate and the air vent. For this purpose, the hardness of the disappeared resin model, which is a cured product, at 80 ° C. is 20-5 in Shore D hardness.
5 was found to be optimal. More preferably 30
-50. When the hardness at 80 ° C is 55 or more in Shore D hardness, the relaxation stress of the cured resin is poor, the stress cannot be dispersed to the sprue and the air vent, and it expands unilaterally, eventually causing the mold to be damaged by the expansive force. Be different. 80 ° C
If the hardness is less than 20 in Shore D hardness, the resin model hardness at summer temperature is less than 40 in Shore D, causing insufficient hardness in the demolding process at the time of resin model manufacturing, and the resin model is forced to demold stress. May be deformed.

As described above, in setting the resin composition for burning model, the amount of resin, the skeleton, the speed of curing, the plasticizer component, the wax,
The present invention has been accomplished by finding an optimal application range in which the melted outflow combustion component of the wax component, the hardness of the cured product, the foaming control, and the like are interrelated.

[0077]

EXAMPLES First, a two-component reaction-curable urethane resin liquid (C)
Examples of are described below.

(Example 1-Resin solution) 34.0 parts by weight of crude MDI (NCO = 32%) in a 3-necked Kolben, 14.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, polypropylene glycol (MW = 200). ) 2.0
Charge the weight, dissolve with uniform stirring, and gradually raise the temperature to 80 ° C.
After stirring for 5 hours, a urethane reaction was carried out to obtain a urethane prepolymer having a terminal NCO. NCO = 20.9%. To this, 0.01 part by weight of an antifoaming agent was added and mixed to obtain a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 18.0 parts by weight of trimethylolpropane / propylene oxide adduct (MW = 400), and 10.0 parts by weight of 2-ethylhexyl adipate as a plasticizer were charged, and while sucking nitrogen gas from the capillary,
The mixture was stirred, mixed at 100 ° C. for 1 hour, and dehydrated. Moisture was measured by Karl Fischer and found to be 0.0
It was 15%. After cooling, 0.01 part by weight of a defoaming agent and a small amount of zinc octylate / xylene solution (10% solution) were added to adjust the pot life to 3 minutes. Further, 5.0 parts by weight of beeswax was added as a wax / wax component to obtain a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated value is NCO / OH 0.88, plasticizer content 24.0
% By weight, polyether chain content 21.7% by weight, wax / wax component content 10.0% by weight, polyfunctional polyol component average functional group number 3.43, polyfunctional polyisocyanate component average functional group The cardinality is 2.33.

(Comparative Example 1-Resin solution) 43.0 parts by weight of crude MDI (NCO = 32%) in a 3-necked corben, 4.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, polypropylene glycol (MW = 200). ) 2.0
A weight was charged, and after uniform stirring and dissolution, the temperature was gradually raised and stirred at 80 ° C. for 5 hours to carry out a urethanization reaction to obtain a urethane prepolymer having a terminal NCO. NCO = 25.0%.
To this, 0.01 part by weight of an antifoaming agent was added and mixed to obtain a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight and 45.0 parts by weight of a bisphenol / propylene oxide adduct (MW = 400) were agitated, mixed and dehydrated under vacuum at 100 ° C. for 1 hour while suctioning nitrogen gas from the capillary. The water content measured by a Karl Fischer was 0.015%.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated values are: NCO / OH 1.02, plasticizer content 5.0% by weight, polyether chain content 23.4% by weight, wax
The content of the wax component was 0% by weight, the average number of functional groups of the polyfunctional polyol component was 2.26, and the average number of functional groups of the polyfunctional polyisocyanate component was 2.32.

[0084]

[Table 1]

(Example 2-Resin Liquid) 32.0 parts by weight of crude MDI (NCO = 32%) in a 3-neck Kolben, 5.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, and 8.0 parts by weight of xylene. Parts were charged and dissolved by uniform stirring. 5.0 parts by weight of beeswax as a wax component was added to this and mixed with stirring. NCO = 20.5%. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 7.0 parts by weight of ethylenediamine / propylene oxide adduct (MW = 400) and trimethylolpropane / propylene oxide adduct (MW = 40)
0) 16.0 parts by weight and 5.0 parts by weight of 2-ethylhexyl adipate as a plasticizer were charged, and the mixture was stirred, mixed and dehydrated under vacuum at 100 ° C. for 1 hour while sucking nitrogen gas from the capillary. The water content measured by a Karl Fischer was 0.02%.

After cooling, 7 parts by weight of xylene was added, mixed and diluted, and a small amount of zinc octylate / xylene solution (10% solution) was added to adjust the working time to 90 seconds. Further, 5.0 parts by weight of beeswax was added as a wax / wax component to obtain a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated value is NCO / OH 0.88, plasticizer content 10.0
% By weight, polyether chain content 21.7% by weight, wax / wax component content 13.0% by weight, polyfunctional polyol component average functional group number 3.40, polyfunctional polyisocyanate component average functional group number. Is 2.37.

(Comparative Example 2-Resin liquid) 36.0 parts by weight of crude MDI (NCO = 32%) in a 3-neck Kolben, 2.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, polypropylene glycol (mw = 200). ) 2.0
By weight, xylene 10 was added by weight, and after uniformly stirring and dissolving, the temperature was gradually raised and mixed at 80 ° C. for 1 hour. NCO = 2
It was 0.5%. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 2.0 parts by weight of trimethylolpropane / propylene oxide adduct (MW = 400), and 33.0 parts by weight of bisphenol / propylene oxide adduct were charged, and vacuum was applied while sucking nitrogen gas from the capillary. At 100 ° C., the mixture was stirred and mixed for dehydration. The water content is 0.0 when measured with a Karl Fisher.
It was 2%.

After cooling, 10.0 parts by weight of xylene was added, mixed and diluted, and a small amount of zinc octylate / xylene solution (10% solution) was added to adjust the pot life to 3 minutes. This was used as a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated values are: NCO / OH 1.03, plasticizer content 2.0% by weight, polyether chain content 21.3% by weight, wax
The wax component content was 0% by weight, the polyfunctional polyol component had an average number of functional groups of 2.37, and the polyfunctional polyisocyanate component had an average number of functional groups of 2.33.

[0093]

[Table 2]

(Example 3-Resin Liquid) 32.0 parts by weight of crude MDI (NCO = 32%) in a 3-necked Kolben, 5.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, and 8.0 parts by weight of xylene. Parts were charged and dissolved by uniform stirring. 5.0 parts by weight of beeswax as a wax component was added to this and mixed with stirring. NCO = 20.5%. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 8.0 parts by weight of ethylenediamine / propylene oxide adduct (MW = 400) and trimethylolpropane / propylene oxide adduct (MW = 40)
0) 16.0 parts by weight and 5.0 parts by weight of 2-ethylhexyl adipate as a plasticizer were charged, and the mixture was stirred, mixed and dehydrated under vacuum at 100 ° C. for 1 hour while sucking nitrogen gas from the capillary. The water content measured by a Karl Fischer was 0.02%.

After cooling, 0.03 part by weight of water was added and homogeneously mixed for 1 hour. Then, 9.0 parts by weight of xylene was added, mixed and diluted to give a zinc octylate / xylene solution (10% solution).
Was added to adjust the pot life to 2 minutes. Further, 5.0 parts by weight of beeswax was added as a wax / wax component to obtain a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated value is NCO / OH 0.77, plasticizer content 10.0
% By weight, polyether chain content 37.0% by weight, wax / wax component content 10.0% by weight, polyfunctional polyol component average functional group number 3.30, polyfunctional polyisocyanate component average functional group number Is 2.30.

(Comparative Example 3-Resin liquid) 36.0 parts by weight of crude MDI (NCO = 32%) in a 3-necked corben, 2.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, polypropylene glycol (mw = 200). ) 2.0
1 part by weight and 10 parts by weight of xylene were charged, and after uniformly stirring and dissolving, the temperature was gradually raised and mixed at 80 ° C. for 1 hour. NCO =
It was 20.5%. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 2.0 parts by weight of trimethylolpropane / propylene oxide adduct (MW = 400), and 33.0 parts by weight of bisphenol / propylene oxide adduct were charged, and vacuum was applied while sucking nitrogen gas from the capillary. The mixture was stirred, mixed and dehydrated at 100 ° C. for 1 hour. The water content measured by a Karl Fischer was 0.
It was 02%.

After cooling, 10.0 parts by weight of xylene was added, mixed and diluted, and a small amount of zinc octylate / xylene solution (10% solution) was added to adjust the pot life to 3 minutes. This was used as a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated values are: NCO / OH 1.03, plasticizer content 2.0% by weight, polyether chain content 21.3% by weight, wax
The wax component content was 0% by weight, the polyfunctional polyol component had an average number of functional groups of 2.37, and the polyfunctional polyisocyanate component had an average number of functional groups of 2.33.

[0102]

[Table 3]

Example 4-Resin liquid: 32.0 parts by weight of crude MDI (NCO = 32%) in a 3-neck Kolben, 5.0 parts by weight of 2-ethylhexyl adipate as a plasticizer, and 8.0 parts by weight of xylene. Parts were charged and dissolved by uniform stirring. 5.0 parts by weight of beeswax as a wax component was added to this and mixed with stirring. NCO = 20.5%. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 8.0 parts by weight of ethylenediamine / propylene oxide adduct (MW = 400) and trimethylolpropane / propylene oxide adduct (MW = 40)
0) 16.0 parts by weight and 3.0 parts by weight of 2-ethylhexyl adipate as a plasticizer were charged, and the mixture was stirred, mixed, and dehydrated under vacuum at 100 ° C. for 1 hour while sucking nitrogen gas from the capillary. The water content measured by a Karl Fischer was 0.02%.

After cooling, 9.0 parts by weight of xylene was added, mixed and diluted to give a zinc octylate / xylene solution (10% solution).
Was added to adjust the pot life to 3 minutes. Further, as a wax / wax component, 5.0 parts by weight of dense wax and 2.0 parts by weight of sawdust having a water content of 10% by weight (wood cutting powder generated at the time of cutting wood) were added, and this was used as a polyfunctional polyol component. did.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated values are NCO / OH 0.83, plasticizer content 8.0% by weight, polyether chain content 21.0% by weight, wax
The content of the wax component was 10.0% by weight, the average number of functional groups of the polyfunctional polyol component was 3.30, and the average number of functional groups of the polyfunctional polyisocyanate component was 2.30.

(Comparative Example 4-Resin Liquid) A 3-necked Kolben was charged with 42.0 parts by weight of crude MDI (NCO = 32%) and 8.0 parts by weight of xylene, and after uniform stirring and dissolution, the temperature was gradually raised. Mix at 80 ° C. for 1 hour. NCO = 26.9%
Met. This was used as a polyfunctional polyisocyanate component.

Then, an ethylenediamine / propylene oxide adduct (MW = 300) was added to the 4-neck Kolben.
0 parts by weight, 3.5 parts by weight of trimethylolpropane / propylene oxide adduct (MW = 400), and 30.0 parts by weight of bisphenol / propylene oxide adduct were charged, and vacuumed while sucking nitrogen gas from the capillary. At 100 ° C., the mixture was stirred and mixed for 1 hour for dehydration. 1.5 parts by weight of water was added and mixed with stirring for 1 hour. The water content is 3.02 when measured with a Karl Fischer
%Met.

After cooling, 8.0 parts by weight of xylene was added, mixed and diluted to give a zinc octylate / xylene solution (10% solution).
Was added to adjust the pot life to 3 minutes. This was used as a polyfunctional polyol component.

The compounding ratio of the polyfunctional polyol component and the polyfunctional polyisocyanate component is 1: 1 (weight). Calculated values are NCO / OH 0.78, plasticizer content 0.0% by weight, polyether chain content 21.3% by weight, wax
The wax component content was 0% by weight, the polyfunctional polyol component had an average number of functional groups of 2.24, and the polyfunctional polyisocyanate component had an average number of functional groups of 2.20.

[0111]

[Table 4]

Next, examples and comparative examples of resin models using these two-component reaction-curable urethane resin solutions (C) are shown below.

The model is an automobile part, and the total model weight is 0.
8 kg, thick part 25 mm, thin part 0.4 mm, vertical longest part 200 mm, horizontal longest part 300 mm, height longest part 20
It is 0 mm. Since it has a complicated shape as a whole and there is no draft, we inverted the master model to a silicone rubber mold and manufactured a model by vacuum casting.

The master model is created by the following method. In other words, by charging the photocurable acrylic resin liquid into the resin container of the stereolithography machine and slightly lowering the vertically movable support stage installed in the resin container from the resin liquid surface, the resin liquid is deposited on the support stage. Supply and form its thin layer. Next, a solid cured resin layer is formed by irradiating this thin layer with light controlled by a computer based on the shape data of the resin model to be molded. Then, a reaction curable resin liquid is supplied onto the cured resin layer to form a further thin layer, and the thin layer is irradiated with light controlled by a computer to continuously form a thin layer on the cured resin layer. Then, a new cured resin layer is formed so as to be integrally laminated. By repeating this process a predetermined number of times with or without changing the pattern of light irradiation by computer control, a plurality of cured resin layers are integrally laminated to form a resin as a three-dimensional three-dimensional object. A model is built. The resin model three-dimensionally shaped in this manner is separated from the support stage of the storage container and taken out. Unreacted resin liquid remaining on the surface of the resin model is washed off with an organic solvent. Examples of the cleaning organic solvent include isopropyl alcohol, ethyl alcohol, acetone, ethyl acetate, and methyl ethyl ketone. Then, post-curing is further performed by light irradiation to completely cure. Then, the burrs protruding to the side surface of the cured resin model are trimmed with a cutter. On the surface of the resin model formed by this,
There was no bleeding and tacking of the plasticizer and it became a normal model. Further, the resin liquid was instantaneously cured by irradiation with light. The hardness of the cured resin model was 75 in Shore D hardness.

The inversion from the master model to the silicon type is as follows. The gate and casting port are decided, the gate of the plastic rod is joined to the master model, it is temporarily fixed in the container, and the release agent treatment is performed. Clear RTV silicone resin liquid (KE1606, Shin-Etsu Chemical Co., Ltd.) and curing agent resin liquid (CAT-RG, Shin-Etsu Chemical Co., Ltd.) were taken out at 20: 1 into a mixing container, mixed with a stirrer, and put in a vacuum defoaming tank. The vacuum state and the degassing leak state are repeated several times, and the mixed bubbles floating on the surface of the resin liquid are broken and defoamed. Then, the mixed transparent RTV silicone resin liquid is slowly poured into the container in which the master model and the gate are temporarily fixed. In order to completely break the bubbles at the time of pouring, the mixture was placed in the vacuum tank again and kept under reduced pressure for 10 minutes for defoaming.
Then, remove it from the vacuum chamber and let it cure at room temperature for one day.
A cured product of transparent RTV silicon including the master model is obtained. Aiming at the particle line described in the master model, the transparent silicon cured product is cut into 2 molds with a knife to take out the master model. Cut the tip of the gate with a cutter to make a casting port. On the other hand, the transparent silicon mold is V-cut with a knife to create an air vent. In this way, a transparent silicon split mold having a casting port and an air bleeding port at the top is created. Then, the split molds are properly aligned along the positioning bosses, firmly fixed with tape, and a plastic funnel is inserted into the casting port and fixed, and used as a tray for the casting resin liquid.

The method of producing each model by vacuum casting from the resin liquids of Examples and Comparative Examples is as follows. A silicone mold is installed in a vacuum tank, and 50 parts of the polyfunctional polyol component (A) is weighed in the two containers that have been set, and 50 parts of the polyfunctional polyisocyanate component (B) is weighed and set in the other container. The vacuum tank is depressurized, and then the container is tilted by rotating a rotary knob that is guided from the container set containing the polyfunctional polyol component (A) in the vacuum tank to the outside of the vacuum tank, and the polyfunctional polyisocyanate component ( The polyfunctional polyol component (A) is poured into a container containing B). Immediately thereafter, the stirring rod attached to the container containing the polyfunctional polyisocyanate component (B) is rotated to mix the two liquids. By rotating the knob for rotation, which is guided from the container of the two-liquid mixture to the outside of the vacuum chamber, the two-liquid mixture is poured into the plastic funnel fixed to the transparent RTV silicon casting port. As a result, the two-liquid mixture is poured into the model-shaped space portion of transparent RTV silicon. Then, the vacuum in the vacuum tank is immediately broken and the inside of the vacuum tank is returned to normal pressure. The work up to this point is carried out satisfactorily, and is completed within about 40 seconds.

Table 5 collectively shows Examples and Comparative Examples of the resin model.

[0118]

[Table 5]

[0119]

[Table 6]

The conditions of precision casting process using a resin model using the reaction-curable resin liquid of the present invention, casting examples, and comparative examples will be described.

The precision casting process after the model production is as follows.

1. Model preparation: Join the sprue made of lost wax to the resin model.

2. Coating: Dip in a slurry composed of zirconia sol and fused zirconia, sprinkle fused zirconia as stucco particles and dry for 3 hours to form a first layer.
Then, it is dipped in a slurry of colloidal silica-mullite, sprinkled with fused silica as stucco particles and dried for 2 hours. This operation is repeated 10 times to complete the coating.

3. Dewaxing: Apply hot air to the sprue of the coated resin model with a dryer and heat for about 1 hour.
Dewaxes the lost wax part and promotes thermal decomposition and liquefaction of the resin model.

4. Primary calcination: After dewaxing, it is placed in a gas furnace, gradually heated and kept at 200 ° C. for 30 minutes to promote thermal decomposition and combustion of the resin model. The temperature is raised gradually to 60 at 550 ° C.
Hold for minutes to burn off the resin model. The temperature is further gradually raised to complete combustion of the resin model and strengthening of the mold at 1100 ° C.

5. Secondary firing: After removing the ash content inside the mold,
It is placed in an electric furnace and fired at 850 ° C. for 1 hour to remove moisture adhering to the mold.

6. Metal melting: In a melting furnace of a vacuum melting casting furnace, Ti-6.4 alloy is melted under an argon gas stream. The melting temperature is 1700 ° C.

7. Casting: Casting is performed immediately after melting the Ti alloy. After casting, it is slowly cooled in the furnace.

8. Disassembling: Remove the casting mold with a hammer, take out the casting, cut the runner, shot blast,
Residual refractory deposits are removed by sandblasting.

Visual inspection: Visually check the appearance shape of the casting, the occurrence of surface voids, the sharpness of edges, and the rib standing of thin parts.

Examples and comparative examples of precision casting with a resin model using a reaction-curable resin liquid are summarized in Tables 7 to 8 and described below.

[0132]

[Table 7]

[0133]

[Table 8]

[0134]

EFFECTS OF THE INVENTION In the precision casting by the lost wax method, when the wax model to be the disappearance model has a portion with a wall thickness of 1 mm or less, the wax model is injection-molded into the mold regardless of the cutting process due to insufficient strength of the wax. Anyway, it is difficult to make. According to the present invention, a model having a wall thickness of 0.5 mm can be easily manufactured. That is, in the present invention,
It becomes possible to produce ultra-thin precision casting parts, such as cameras, watches,
Shaving / mobile phones, automobile parts, aircraft parts, etc. Precision casting parts are widely applied, producing a great effect.

In the case of a wax model having a wall thickness of approximately 1 mm, the resin model of the present invention is a wax model, although the thin portion is easily damaged and bent or broken unless careful handling is performed. Is far superior in strength and elasticity.

Especially, the production quantity is 1,000 pieces, 10,0 pieces.
If the number increases to 00, even with the utmost care, it has been a very difficult task with the conventional wax model. However, with the resin model of the present invention, the strength and elasticity of the model itself are far greater. Since it is excellent in precision, there is an effect that it is very easy for precision casting companies to handle the model.

Further, the wax model is hard to produce a sharp edge, but the resin model according to the present invention has a beautiful sharp edge because the model surface is covered with resin and the wax component is buried in the resin skeleton. be able to. As described above, since a resin model having a resin as a skeleton has a variety of shapes, the thin product having a complicated shape has an absolute advantage.

Furthermore, since the conventional wax model has a high risk of its shape being collapsed at the temperature of midsummer, it has been required to be stored in a temperature-controlled room. However, the resin model in which the wax component is buried in the resin skeleton according to the present invention. In the case of, since it has sufficient hardness to retain its shape even in the temperature of midsummer, there is also an effect that it is not necessary to perform strict control such that it must be stored in a temperature-controlled room.

Furthermore, in the resin model according to the present invention,
Since it contains a large amount of plasticizer components, it is easy to melt, decompose, and flow out during the dewaxing / firing process, and the mold does not crack. Moreover, since the wax component is added, this effect becomes more and more effective. Furthermore, the effect is immeasurable because a fine foamed resin model is obtained by adding water.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08G 101: 00) (72) Inventor Masayuki Tanaka 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. Company (72) Inventor Toshinobu Kasuga 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. (72) Inventor Keiichiro Onzo 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. Company (72) Inventor Reiji Matsuyama 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. (72) Inventor Hisa Mizuno 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. (72) Inventor Akira Takase 3-11-10 Hashimotodai, Sagamihara City, Kanagawa Shonan Design Co., Ltd. (72) Inventor Ryuji Oi Kanagawa Prefecture 3-11-10 Hashimotodai, Sagamihara-shi Shonan Design Co., Ltd. (72) Inventor Minoru Matsumura 3-11-10 Hashimotodai, Sagamihara-shi, Kanagawa Shonan Design Co., Ltd. (72) Inventor Kitataro Sagamihara-shi, Kanagawa Hashimotodai 3-11-10 Shonan Design Co., Ltd. (72) Inventor Kazuki Kamata Sagamihara City, Kanagawa Prefecture 3-11-10 Hashimotodai Shonan Design Co., Ltd. (72) Inventor Masato Kikuchi Hashimotodai, Sagamihara City, Kanagawa Prefecture 3-11-10 Shonan Design Co., Ltd. F term (reference) 4E093 GA01 GA03 GA04 GA06 GA07 GD01 4J034 BA05 BA06 BA07 BA08 CA03 CA04 CA05 CA14 CA15 CA19 CB02 CB03 CB04 CB05 CB07 DF08 DG08 DB03 DF20 DF12 DF12 DG04 DG14 DP18 DP20 GA06 HA01 HA06 HA07 HC12 HC13 HC22 HC33 HC34 HC35 HC46 HC52 HC61 HC64 HC67 HC71 HC73 MA12 MA22 MA26 NA03 QA02 QA03 QC01 QD03 RA11 SA02

Claims (9)

[Claims] 1. A burnout resin model used in the lost wax method, wherein a two-component reaction-curable urethane resin liquid (C) comprising a polyfunctional polyol component (A) and a polyfunctional polyisocyanate component (B) is added to a plasticizer. (D) is contained in an amount of 1 to 30% by weight and a wax component (E) is included in an amount of 1 to 20% by weight to form a resin liquid composition, and the resin liquid composition is used for a usable time of 5 minutes or less. A burned-off resin model that is formed by curing with. 2. In the two-component reaction-curable urethane resin liquid, the polyfunctional polyol component (A) has an average number of functional groups of 2.8 or more, and the polyfunctional polyisocyanate component (B) has 2.0. With the average number of functional groups above,
And the NCO / OH is 0.7 to 1.0, and the burned resin model according to claim 1. 3. The burn-off resin model according to claim 1, wherein the plasticizer (D) is phase-separated and micro-dispersed when the two-component reaction-curable urethane resin liquid (C) is reactively cured. . 4. The two-component reaction-curable urethane resin liquid (C) contains 2 to 25% by weight of a polyether chain represented by the following chemical structural formula. The burned-off resin model described in any one. [Chemical 1] 5. The wax component (E) is in the form of granules, flakes or lumps and has a size of about 1 cm ³ , which is one of the claims 1 to 4. The burned-off resin model described. 6. The two-component reaction-curable urethane resin liquid (C) contains 0.01 to 1.0% by weight of water (F), and is foamed with water. The burned-off resin model described in any one. 7. The two-component reaction-curable urethane resin liquid (C) contains 10 to 25% by weight of an organic solvent (G), according to any one of claims 1 to 5. Burnt resin model. 8. The fine particles (H) of natural polymer waste are added to the two-component reaction-curable urethane resin liquid (C) in an amount of 1 to 1.
The burned resin model according to any one of claims 1 to 6, wherein the burned resin model contains 0%. 9. A precision casting method using the burned resin model according to any one of claims 1 to 8.