JP2019171449A - Method for manufacturing casting mold, and mold for molding casting mold and method for manufacturing the same - Google Patents

Abstract

A method for manufacturing a mold capable of manufacturing a mold with simple equipment with high productivity, and securing a necessary pot life, and shortening the time required for removing a mold, and a mold for forming a mold suitable for the method of manufacturing the mold. And its manufacturing method. A mold-forming mold made of a material that transmits microwaves is filled with a mold-forming sand composition containing a refractory granular material, an acid-curable resin, and a curing agent, and irradiated with microwaves. A method for producing a mold, comprising curing an acid-curable resin contained in the sand composition for molding a mold. [Selection diagram] None

Description

  The present invention relates to a mold manufacturing method, a mold making mold, and a manufacturing method thereof.

  Conventionally, a self-hardening mold is known as one of casting molds. A self-hardening mold is a refractory granular material such as silica sand, a binder mainly composed of an acid curable resin, a curing agent such as an organic acid such as xylene sulfonic acid, and an inorganic acid such as sulfuric acid or phosphoric acid. Are added and kneaded, and then the obtained kneaded sand is filled into a mold making mold and the binder is cured.

  An acid curable resin is a resin that undergoes polycondensation while being dehydrated with an acid (curing agent) and cures. If the pot life is too short, the acid curable resin is not filled before the kneaded sand is filled into the mold for molding. It may harden. Therefore, it is required to ensure a sufficient pot life. On the other hand, after the kneaded sand is filled into the mold for mold making, the acid curable resin is preferably cured quickly from the viewpoint of productivity, and the time for removing the mold is preferably short.

In order to shorten the die-cutting time, a curing agent having a high curing rate may be used. However, when a curing agent having a high curing rate is used, a sufficient pot life cannot be secured. On the other hand, if a curing agent having a slow curing rate is used, the pot life can be sufficiently secured, but the mold release time tends to be long.
As described above, it is difficult to achieve both the securing of the pot life and the shortening of the mold removal time.

In recent years, a method for curing kneaded sand in a short time by microwave irradiation has been proposed.
For example, in Patent Document 1, a mold making mold made of a sulfide sulfone-based resin material and provided with air holes is filled with kneaded sand containing an inorganic binder such as water glass. A method for producing a mold by heating and curing a binder by irradiation is disclosed.
In Patent Document 2, a mold making mold made of urethane resin is filled with kneaded sand containing an inorganic binder such as water glass, and the binder is heated and cured by irradiation with microwaves in a reduced pressure atmosphere. A method of manufacturing a mold is disclosed.
In patent document 3, after laminating | mixing the mixture containing a fireproof granular material and ester which is a hardening | curing agent, and repeating the operation which prints the resole resin which is a binding agent on it, after hardening a binding agent primarily, A method for producing a mold by irradiating with microwaves and performing secondary curing to remove a mixture of non-printing parts is disclosed.

JP 7-195139 A JP 2004-98160 A Special table 2017-515682 gazette

However, as described in Patent Documents 1 and 2, when an inorganic binder such as water glass is used as a binder, vapor generated by microwave irradiation is emitted from a vent hole provided in the mold for mold making. It must be discharged or removed using a decompression device.
In the method described in Patent Document 3, since the curing process is performed twice, the process becomes complicated, the productivity is poor, and the cost is increased.

  The present invention has been made in view of the above circumstances, and a mold manufacturing method capable of manufacturing a mold with simple equipment and high productivity, and shortening a mold-release time while ensuring a necessary pot life, and the mold An object of the present invention is to provide a mold for mold making suitable for the manufacturing method and a manufacturing method thereof.

The present invention has the following aspects.
[1] A mold making mold made of a material that transmits microwaves is filled with a sand mold molding mold containing a refractory granular material, an acid curable resin, and a curing agent, and irradiated with microwaves. A method for producing a mold, comprising: curing an acid curable resin contained in a sand molding composition.
[2] The process for producing a mold according to [1], wherein the sulfur atom content in the curing agent is 1.5 to 6.0% by mass with respect to the total mass of the curing agent.
[3] The method for producing a mold according to [1] or [2], wherein a sulfur atom content in the curing agent is 0.8 to 2.6 parts by mass with respect to 100 parts by mass of the acid curable resin. .
[4] The sulfur atom content in the curing agent is 0.07 to 0.20 parts by mass with respect to 1000 parts by mass of the refractory granular material, according to any one of [1] to [3]. A method for producing a mold.
[5] In any one of [1] to [4], the content of water in the mold molding sand composition is 3 to 4 parts by mass with respect to 1000 parts by mass of the refractory granular material. A method for producing the mold described above.
[6] A mold making mold made of a material having a relative dielectric constant (ε _r ) of 7 or less.
[7] The mold for mold making according to [6], wherein the material includes glass and polyamide.
[8] The mold for mold making according to [6] or [7], which is used in a method for producing a mold having a microwave irradiation step.
[9] A method for producing a mold for mold making according to any one of [6] to [8], wherein the mold for mold making is produced by three-dimensional additive manufacturing.
[10] The method for producing a mold according to any one of [1] to [5], wherein the mold for molding is the mold for molding according to any one of [6] to [8]. .

  ADVANTAGE OF THE INVENTION According to this invention, the casting_mold | template manufacturing method which can manufacture a casting_mold | template with simple equipment with high productivity, and can shorten a die-cutting time while ensuring the required pot life, and the casting_mold | template suitable for the manufacturing method of the said casting_mold | template A mold for molding and a manufacturing method thereof can be provided.

[Sand composition for mold making]
The mold molding sand composition used in the present invention (hereinafter simply referred to as “sand composition”) includes a refractory granular material, an acid curable resin, and a curing agent.

<Fireproof granular material>
As the refractory granular material, conventionally known materials such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Moreover, the thing which collect | recovered used refractory granular materials (collected sand), the thing which regenerated (regenerated sand), etc. can be used. These refractory granular materials may be used alone or in combination of two or more. Among these, silica sand is preferable because it easily transmits microwaves.

<Acid curable resin>
The acid curable resin is generally a resin mainly composed of furfuryl alcohol, urea, phenols, aldehydes, etc., and is cured by polycondensation while dehydrating with an acid. The acid curable resin serves as a binder.

  Examples of aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propyl aldehyde, benzaldehyde, salicylaldehyde, glyoxal, and furfural. These aldehydes may be used individually by 1 type, and may use 2 or more types together. Among these, formaldehyde is preferable in that curing proceeds sufficiently.

  Examples of phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E, bisphenol F, and bisphenol Z. These phenols may be used individually by 1 type, and may use 2 or more types together.

The following four examples are particularly preferable for the acid curable resin. In addition, the (co) condensate in the following means at least one of a condensate and a cocondensate.
i) A mixture of a (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes with furfuryl alcohol.
ii) A mixture of urea and aldehyde condensate and furfuryl alcohol.
iii) A (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes, a mixture of phenol and aldehydes, and a mixture of furfuryl alcohol.
iv) A mixture of phenol and aldehyde condensate and furfuryl alcohol.

It is preferable that the acid curable resin is in such an embodiment of i) to iv) because a sand composition can be obtained in which the pot life can be set more easily and the mold strength can be further improved.
In the aspect of i), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 15 to 45% by mass, and 25 to 35% by mass. Is more preferable. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the aspect of ii), the ratio of the condensate of urea and aldehydes in the acid curable resin is preferably 3.5 to 20% by mass, and more preferably 6.9 to 13.5% by mass. The ratio of furfuryl alcohol is preferably 80 to 96.5% by mass, and more preferably 86.5 to 93.1% by mass.
In the embodiment of iii), the ratio of the (co) condensate obtained by condensing urea, furfuryl alcohol and aldehydes in the acid curable resin is preferably 7.5 to 22.5% by mass, More preferably, it is 5 to 17.5% by mass. The ratio of the condensation product of phenol and aldehyde is preferably 7.5 to 22.5% by mass, and more preferably 12.5 to 17.5% by mass. The ratio of furfuryl alcohol is preferably 55 to 85% by mass, and more preferably 65 to 75% by mass.
In the aspect of iv), the ratio of the condensate of phenol and aldehyde in the acid curable resin is preferably 10 to 40% by mass, and more preferably 20 to 30% by mass. The ratio of furfuryl alcohol is preferably 60 to 90% by mass, and more preferably 70 to 80% by mass.

The acid curable resin can be obtained by a general production method. An example is shown below.
First, acid curable resin raw materials (furfuryl alcohol, aldehydes, urea, phenols, etc.) are mixed, an aqueous solution of a basic catalyst is added, and the pH of the mixture is adjusted to 9 to 11 to make it alkaline. Next, the temperature of the mixture is raised to cause an addition reaction between urea and aldehydes to generate a reaction product (first step). An acidic catalyst is added to the obtained reaction liquid, the pH of the reaction liquid is adjusted to 2 to 5 to make it acidic, and a condensation reaction such as an addition reaction product of urea and aldehydes proceeds (second step). Thereafter, an aqueous solution of a basic catalyst is added to the reaction liquid, the pH of the reaction liquid is adjusted to 7 to 10 to make it alkaline, the additive is mixed and reacted (third step), and the additive is added as necessary. Further, it is added to obtain a reaction product containing an acid curable resin.

Examples of the basic catalyst include sodium hydroxide and potassium hydroxide.
Examples of the acidic catalyst include hydrochloric acid, sulfuric acid, paratoluenesulfonic acid and the like.
In addition, since there is little addition amount of an acidic catalyst, it does not progress to hardening reaction.

  When producing the condensate of urea and aldehydes, it is preferable to use 1-3 mol of aldehydes with respect to 1 mol of urea. If the amount of the aldehyde used is 1 mol or more, it becomes a condensate with a low degree of polymerization, so that the pot life can be set more easily. On the other hand, if the amount of the aldehyde used is 3 mol or less, a condensate having a high degree of polymerization is obtained, so that the template strength is better expressed.

Examples of the additive include a silane coupling agent and a formaldehyde reducing agent.
If a silane coupling agent is used as an additive, the strength of the mold is further improved. Examples of the silane coupling agent include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane. These silane coupling agents may be used individually by 1 type, and may use 2 or more types together.
The formaldehyde reducing agent is for reducing formaldehyde generated during mold making. Examples of formaldehyde reducing agents include urea, resorcinol, gallic acid, pyrogallol and the like. These formaldehyde reducing agents may be used alone or in combination of two or more.

The reaction product thus obtained includes an acid curable resin, water, and optionally a silane coupling agent.
The acid curable resin contains components used for reactions other than water and silane coupling. Specifically, one or more selected from the group consisting of furfuryl alcohol, phenols and urea and an aldehyde 1 type (s) or 2 or more types of the condensate or cocondensate with a class, furfuryl alcohol, and the condensate of furfuryl alcohol are contained. In the production of the acid curable resin, when a formaldehyde reducing agent is used as an additive, the formaldehyde reducing agent is also included in the acid curable resin. The unreacted furfuryl alcohol serves as a diluent for reducing the entire acid-curable resin to a low viscosity, and becomes a resin and becomes a cured product in the curing reaction.
The water is water derived from bound water generated when the condensate or cocondensate is formed, or water supplied from an aqueous raw material (for example, formalin). Moreover, the water added as needed is also contained.
The silane coupling agent is a silane coupling agent used as an additive in the production of the acid curable resin. Moreover, the silane coupling agent added as needed after manufacture of acid curable resin is also contained.

The content of each component in the reaction product varies depending on the conditions of the production method, the molecular weight of the acid curable resin, the amount of additive added, and the like, for example, as follows.
The content of the acid curable resin is preferably 70 to 95% by mass, more preferably 75 to 90% by mass, further preferably 75 to 85% by mass, and more preferably 80 to 85% by mass with respect to the total mass of the reaction product. Is particularly preferred.
5-30 mass% is preferable with respect to the total mass of a reaction product, as for content of water, 10-25 mass% is more preferable, 15-25 mass% is further more preferable, 15-20 mass% is especially preferable. .
As for content of a silane coupling agent, 10 mass% or less is preferable with respect to the total mass of a reaction product, 0.1-9 mass% is more preferable, 0.1-5 mass% is further more preferable.

The nitrogen atom content derived from urea or the like is preferably 0.1 to 6% by mass and more preferably 0.1 to 4.5% by mass with respect to the total mass of the reaction product.
The nitrogen atom content affects the initial strength and final strength of the template. When the nitrogen atom content is low, the initial strength of the template tends to be high, and when the nitrogen atom content is high, the template is high. The final strength of the steel tends to increase.
Therefore, it is preferable to appropriately adjust the nitrogen atom content as necessary. If the nitrogen atom content is within the above range, a template having an excellent balance between the initial strength and the final strength can be easily obtained.

<Curing agent>
Examples of the curing agent include inorganic acids such as sulfuric acid, phosphoric acid, and hydrochloric acid; and organic acids such as organic sulfonic acid and carboxylic acid.
An organic sulfonic acid is an organic compound in which a sulfo group is substituted with a carbon skeleton. Examples of the organic sulfonic acid include xylene sulfonic acid, paratoluene sulfonic acid, benzene sulfonic acid, and methane sulfonic acid. These sulfonic acids may be used alone or in combination of two or more.
Examples of the carboxylic acid include formic acid, acetic acid, oxalic acid, lactic acid, maleic acid, malic acid, citric acid, tartaric acid, malonic acid, succinic acid, benzoic acid and the like. These acids having a carboxylic acid may be used alone or in combination of two or more.

A hardening | curing agent can be selected and used according to the temperature of working environments, such as the time of preparation of a sand composition, and the time of the filling of the sand composition to the mold for mold making.
As the curing agent, it is preferable to use at least an organic acid from the viewpoint that the pot life is long and the normal temperature strength of the mold is further improved. As the organic acid, an organic sulfonic acid is preferable in that the normal temperature strength and heat resistance of the template are further increased, and among them, xylene sulfonic acid and paratoluene sulfonic acid are more preferable in terms of excellent performance as a curing agent. As the organic acid, an organic sulfonic acid and a carboxylic acid may be used in combination.

Moreover, you may use together an inorganic acid and an organic acid as a hardening | curing agent. When an inorganic acid and an organic acid are used in combination, it is preferable that the ratio of the organic acid is larger than that of the inorganic acid.
By the way, sulfuric acid, which is an inorganic acid, is one of the highly versatile curing agents because of its high curing speed and low cost. However, when sulfuric acid is used, the sulfur atom content in the curing agent increases, and the sulfur atom content in the resulting template also increases. When a casting is manufactured using such a mold, the surface of the resulting casting, that is, the surface in contact with the mold, is easily affected by sulfur in the mold. For example, cast iron contains carbon and becomes spherical when the casting cools. Under the influence of sulfur, the carbon on the casting surface is less likely to be spherical, and the metal stretchability and casting strength tend to decrease. Therefore, the surface of the casting may be shaved, and the yield is reduced.
Thus, sulfur atoms in the curing agent can cause casting defects. In addition, since sulfuric acid has a high curing rate, it tends to be difficult to ensure sufficient pot life, particularly when the temperature is high, such as in summer. Therefore, it is preferable that the curing agent does not substantially contain sulfuric acid. Here, substantially not containing sulfuric acid means that the content of sulfuric acid is less than 1% by mass relative to the total mass of the curing agent.

The sulfur atom content in the curing agent is preferably 1.5 to 6.0% by mass, more preferably 2.0 to 5.0% by mass, and 2.5 to 4.0% with respect to the total mass of the curing agent. More preferred is mass%.
The sulfur atom content in the curing agent is preferably 0.8 to 2.6 parts by mass, more preferably 1.0 to 2.0 parts by mass, and 1.3 to 1 with respect to 100 parts by mass of the acid curable resin. More preferably, 7 parts by mass.
The sulfur atom content in the curing agent is preferably 0.07 to 0.20 parts by mass, more preferably 0.09 to 0.18 parts by mass with respect to 1000 parts by mass of the refractory granular material, and 0.10 to 0 More preferably, 13 parts by mass.
If the sulfur atom content in the curing agent is within the above range, the sulfur atom content in the mold can be sufficiently reduced, so that the influence of sulfur on the casting can be reduced. Moreover, even if the temperature is high, sufficient pot life can be secured.
The sulfur atom content in the curing agent can be controlled by the type and composition of the curing agent.

The curing agent can be used in the form of an aqueous solution, that is, as a curing agent aqueous solution.
The content of the curing agent with respect to the total mass of the aqueous curing agent solution is preferably 20 to 75% by mass, and more preferably 30 to 70% by mass.
25-80 mass% is preferable and, as for content of water with respect to the total mass of hardening | curing agent aqueous solution, 30-70 mass% is more preferable.
The aqueous curing agent solution may contain a solvent (other solvent) other than water, and examples of the other solvent include alcohols such as methanol, ethanol, and butanol.

<Optional component>
The sand composition may contain components (arbitrary components) other than the above-described refractory granular material, acid curable resin, and curing agent.
Examples of optional components include silane coupling agents, water, and other solvents.

The silane coupling agent includes all of the silane coupling agent derived from the additive used in the production of the acid curable resin and the silane coupling agent added separately as needed.
Condensed water derived from the production of the acid curable resin, water supplied by an aqueous raw material (for example, formalin, etc.), water derived from the aqueous curing agent solution, added separately as needed. Contains all of the water.
The other solvents include all other solvents derived from the aqueous curing agent solution and other solvents added separately as necessary.

<Content>
The content of each component in the sand composition is as follows.
0.1-2 mass parts is preferable with respect to 100 mass parts of refractory granular materials, and, as for content of acid curable resin, 0.2-1 mass part is more preferable. If content of acid curable resin is more than the said lower limit, a template with higher intensity | strength will be easy to be obtained. If content of acid curable resin is below the said upper limit, it will become easy to disassemble the casting mold after pouring.
As for content of a hardening | curing agent, 0.06-1.2 mass part is preferable with respect to 100 mass parts of refractory granular materials, and 0.08-1 mass part is more preferable. When the content of the curing agent is within the above range, a mold having higher strength is easily obtained.
As for water content, 3-4 mass parts is preferable with respect to 1000 mass parts of refractory granular materials. If water content is more than the said lower limit, since it will generate | occur | produce enough heat | fever when it irradiates with a microwave, hardening of a binder composition will advance easily. If water content is below the said upper limit, a die-cutting time can be shortened more.

[Mold for mold making]
The mold making mold used in the present invention is made of a material that transmits microwaves.
The transmission of microwave means that at least a part of the microwave passes through the mold making mold to such an extent that heat generation necessary to accelerate hardening of the sand composition filled in the mold making mold is generated. Specifically, this means that the relative dielectric constant (ε _r ) of the material is 7 or less. The relative dielectric constant is preferably 6 or less, and more preferably 5 or less. The lower limit value of the relative dielectric constant is not particularly limited.
The relative dielectric constant is obtained by a cavity resonance perturbation method. Specifically, for example, the material is molded into a size of width 50.0 mm × length 50.0 mm × thickness 1.5 mm at room temperature, and the dielectric constant (ε) is obtained for the obtained molding by a cavity resonance perturbation method. _r ) is measured.

Examples of materials that transmit microwaves include glass, preferably soda-lime glass (ε _r = 6.0 to 8.0), polyamide (ε _r = 3.5 to 5.0), epoxy resin (ε _r = 2.5-6.0), polystyrene (ε _r = 2.4-2.6), silicone resin (ε _r = 3.5-5.0), polyurethane (ε _r = 5.0-5.3) ) And polylactic acid (ε _r = about 3). These materials may be used alone or in combination of two or more.
Among these, when manufacturing a mold for mold making by three-dimensional additive manufacturing, it is preferable to use glass (preferably soda-lime glass) and polyamide together.

The method for producing the mold for mold making is not particularly limited, and examples thereof include injection molding and three-dimensional additive manufacturing. Moreover, after shape | molding the material mentioned above in plate shape so that it may become desired thickness, you may manufacture the type | mold for mold making by cutting a plate-shaped molded object so that it may become a desired shape. In particular, it is preferable to manufacture a mold making mold by three-dimensional additive manufacturing because it has a high degree of freedom in shape and can be easily manufactured even in a complicated shape.
Hereinafter, an example of a method for producing a mold for mold making by three-dimensional additive manufacturing will be described.

As the three-dimensional additive manufacturing, a selective laser sintering method (SLS method: Selective Laser Sintering method) is suitable.
First, three-dimensional data of a cross-sectional shape at a constant interval of a target mold making mold is created in advance, and a thin layer made of the material powder is laminated on a work table based on the three-dimensional data. The thin layer is heated by scanning and irradiating the thin layer with the powder of the material. Next, another thin layer made of the powder of the material is laminated on the thin layer after sintering, and the operation of scanning and irradiating a laser is repeated, so that the mold making die made of the melt-bonded material is obtained. can get.

[Mold manufacturing method]
The mold manufacturing method of the present invention includes a step of filling the mold making mold with the sand composition and irradiating microwaves to cure the acid curable resin contained in the sand composition.

The microwave irradiation conditions are set according to the size of the mold to be obtained and the blending composition of the mold making sand composition. For example, the surface temperature of the sand composition filled in the mold making mold is 50 to It is preferable to control the output and the irradiation time so as to be 70 ° C.
If the output is too high, the sand composition and the resulting mold making mold may be melted. Therefore, the output is preferably 600 W or less, and more preferably 500 W or less. Further, from the viewpoint of shortening the irradiation time, 200 W or more is preferable, and 400 W or more is more preferable.
If the irradiation time is too long, the sand composition or the resulting mold making mold may be melted. Therefore, it is preferable to set the irradiation time according to the output.
Further, the microwave may be irradiated in multiple times by changing at least one of the output and the irradiation time.

  According to the method for producing a mold of the present invention described above, the curing of the acid curable resin, which is a binder, is accelerated by irradiation with microwaves, so that the acid curable resin is cured in a short time, and the mold release time can be reduced. . Therefore, even a curing agent having a slow curing rate can be used, and the curing agent can be freely selected according to the temperature of the working environment such as when the sand composition is prepared or when the sand composition is filled in the mold for molding. Therefore, the adjustment of the pot life is easy and the necessary pot life can be secured.

  In addition, since an acid curable resin is used as the binder in the present invention, the water content in the sand composition is less than that of an inorganic binder such as water glass. Moisture in the sand composition is used for heat generation during microwave irradiation, but the amount of steam generated is smaller than when an inorganic binder is used. Therefore, if it is this invention, it is not necessary to use the decompression device which accelerates | stimulates discharge of a vapor | steam, and a casting_mold | template can be manufactured with simple equipment. In addition, according to the present invention, it is not necessary to cure the acid curable resin twice, so that the mold can be manufactured with high productivity.

  Further, according to the present invention, since it is possible to remove the mold in a short time, it is not necessary to dare to use a curing agent having a high curing rate such as sulfuric acid. If a curing agent substantially free of sulfuric acid is used, a long pot life can be obtained. In addition, since the sulfur atom content in the mold can be sufficiently reduced, the influence of sulfur on the casting can be reduced.

  Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto. Various measurement and evaluation methods and preparation of the acid curable resin are as follows.

(Measurement of water content)
The water content was measured as follows based on the Karl Fischer (KF) titration method.
About 2 mL of sample was collected in a dropper and weighed. Next, the weighed sample was injected into an automatic moisture measuring device (Hiranuma Sangyo Co., Ltd. “AQV-2200”) containing about 50 mL of methanol. In addition, K. The F reagent was added dropwise to confirm that it was in an anhydrous state. The dropper after the sample injection was weighed, and the mass difference between the dropper before and after the sample injection was input to the automatic moisture measuring apparatus as the sample collection amount. After sample injection, stir for 1 minute. The amount of water was quantified by dropping F reagent. K. As the F reagent, “Hydranal Composite 5” manufactured by Hayashi Pure Chemical Industries, Ltd. was used.

(Measurement of nitrogen atom content)
The nitrogen atom content was determined by the titration method of the factory wastewater test method of JIS K 0102.

(Measurement of pot life)
The pot life was determined by JACT test method HM-2. If the pot life was 30 minutes or more, it was judged that there was no problem in practice.

(Evaluation of die cutting)
Ease of taking out the test piece from the mold for mold making after 10 minutes from the start of kneading of the refractory granular material, the acid curable resin and the curing agent, and whether or not the shape of the test piece could be maintained Evaluation was made according to the following evaluation criteria.
○: The shape can be easily maintained at the time of taking out, and the compressive strength can be measured with a desktop counter pressure tester.
Δ: Although the shape is partially collapsed at the time of taking out, the compressive strength can be measured with a desktop pressure tester.
X: The shape collapses when taken out, and the compressive strength cannot be measured with a desktop counter pressure tester.

(Measurement of compressive strength)
The compressive strength of the test piece was measured by using a desktop counter pressure tester (manufactured by Takachiho Machine Co., Ltd.) in accordance with the test method for foundry sand of JIS Z 2601.

(Preparation of acid curable resin (a))
In a reaction vessel equipped with a thermometer, a condenser and a stirrer, 70.4 parts by mass of furfuryl alcohol, 4.0 parts by mass of urea, 8.4 parts by mass of a 92% by mass aqueous formaldehyde solution, and 15% by mass sodium hydroxide An aqueous solution (0.1 part by mass) was added and reacted at 80 ° C. for 1 hour (first step: first addition reaction). Thereafter, 0.3 part by mass of 10% by mass hydrochloric acid was added, and further reacted at 80 ° C. for 3 hours (second step: condensation reaction). Thereafter, 0.2 parts by mass of a 15% by mass aqueous sodium hydroxide solution and 2.4 parts by mass of urea as a formaldehyde reducing agent are added to the reaction solution, and further reacted at 80 ° C. for 30 minutes (third step: second step Addition reaction), a reaction mixture was obtained. In the obtained reaction mixture, 1.0 part by mass of resorcinol as a formaldehyde reducing agent, 0.2 part by mass of gallic acid, and 0.2 part by mass of N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane as a silane coupling agent 12.8 parts by mass of water were added to obtain 100 parts by mass of a reaction product (a) containing the acid curable resin (a).
The content of the acid curable resin (a) with respect to the total mass of the obtained reaction product (a) is 81.3% by mass, the content of the silane coupling agent is 0.2% by mass, and water The content of was 18.5% by mass, and the nitrogen atom content was 3.5% by mass.

(Preparation of acid curable resin (b))
The acid curable resin (b) is the same as the preparation of the acid curable resin (a) except that the amount of furfuryl alcohol is changed to 68.9 parts by mass and the amount of water is changed to 14.3 parts by mass. The reaction product (b) containing 100 parts by mass was obtained.
The content of the acid curable resin (b) is 79.8% by mass with respect to the total mass of the obtained reaction product (b), the content of the silane coupling agent is 0.2% by mass, The content of was 20% by mass, and the nitrogen atom content was 3.5% by mass.

(Preparation of acid curable resin (c))
The acid-curable resin (c) is the same as the preparation of the acid-curable resin (a) except that the amount of furfuryl alcohol is changed to 63.9 parts by mass and the amount of water is changed to 19.3 parts by mass. The reaction product (c) containing 100 parts by mass was obtained.
The content of the acid curable resin (c) with respect to the total mass of the obtained reaction product (c) is 74.8% by mass, the content of the silane coupling agent is 0.2% by mass, The content of was 25% by mass, and the nitrogen atom content was 3.5% by mass.

(Preparation of acid curable resin (d))
The acid-curable resin (d) is the same as the preparation of the acid-curable resin (a) except that the amount of furfuryl alcohol is changed to 83.0 parts by mass and the amount of water is changed to 0.2 parts by mass. The reaction product (d) containing 100 parts by mass was obtained.
The content of the acid curable resin (d) with respect to the total mass of the obtained reaction product (d) is 94.8% by mass, the content of the silane coupling agent is 0.2% by mass, The content of was 5% by mass, and the nitrogen atom content was 3.5% by mass.

(Manufacture of mold making mold (α))
Polyamide 11 (ε _r = 4.3) and soda lime glass (ε _r = 6.0) were mixed in a mass ratio (polyamide 11: soda lime glass) = 50: 50. Using the resulting mixture, based on the SLS method, a laser sintering machine (“EOSINT P380” manufactured by EOS) used to prepare test pieces in which four cylindrical molds with an inner diameter of 50 mm and a height of 50 mm were formed. A mold making mold (α) was prepared.

[Example 1]
<Preparation of sand assembly>
Xylene sulfonic acid, lactic acid, methanol and water were mixed at a mass ratio (xylene sulfonic acid: lactic acid: methanol: water) = 20: 20: 5: 55 to prepare an aqueous curing agent solution.
To 100 parts by mass of silica sand (manufactured by Mitsubishi Corporation Building Materials Co., Ltd., Freemantle Shinsuna), 0.8 part by mass of the reaction product (a) and 0.32 parts by mass of the aqueous curing agent solution are added, and a Shinagawa universal agitator (stock) A sand composition was obtained by kneading with MIXER.
The obtained sand composition contains 0.650 parts by mass of the acid curable resin (a) and 0.128 parts by mass of the curing agent with respect to 100 parts by mass of the refractory granular material, and 1000 parts by mass of the refractory granular material. In contrast, 3.24 parts by mass of water is contained.

<Manufacture of test pieces>
A part of the obtained sand composition was immediately filled in a mold making mold (α) under the conditions of a temperature of 25 ° C. and a humidity of 50%. Immediately, the mold making mold (α) filled with the sand composition was put into a microwave generator, irradiated with microwaves (2.45 GHz) for 2 minutes at an output of 500 W, and then microwaves (2 for 2 minutes at 200 W). .45 GHz) was applied to cure the acid curable resin (a).
After irradiation, the mold making mold (α) is taken out from the microwave generator, and when the test piece is taken out from the mold making mold (α) after 10 minutes from the start of kneading, It was evaluated whether or not the shape could be maintained. The results are shown in Table 1.

[Example 2]
A sand composition and a test piece were produced and evaluated in the same manner as in Example 1 except that the reaction product (b) was used. The results are shown in Table 1.
The sand composition obtained in Example 2 contains 0.638 parts by mass of the acid curable resin (b) and 0.128 parts by mass of the curing agent with respect to 100 parts by mass of the refractory granular material. 3.36 parts by mass of water is included with respect to 1000 parts by mass of the particulate material.

[Example 3]
A sand composition and a test piece were produced and evaluated in the same manner as in Example 1 except that the reaction product (c) was used. The results are shown in Table 1.
The sand composition obtained in Example 3 contains 0.598 parts by mass of the acid curable resin (c) and 0.128 parts by mass of the curing agent with respect to 100 parts by mass of the refractory granular material. 3.76 parts by mass of water is included with respect to 1000 parts by mass of the particulate material.

  In Table 1 and Table 2 shown below, “content of acid curable resin” and “content of curing agent” are amounts (parts by mass) relative to 100 parts by mass of the refractory granular material. “Water content” is an amount (part by mass) relative to 1000 parts by mass of the refractory granular material.

  From the results in Table 1, in Examples 1 to 3, the mold could be removed in 10 minutes from the start of curing.

[Example 4]
A sand composition was prepared in the same manner as in Example 1. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.

A part of the obtained sand composition was immediately filled in a mold making mold (α) under the conditions of a temperature of 25 ° C. and a humidity of 50%. Immediately, the mold making mold (α) filled with the sand composition was put into a microwave generator, irradiated with microwaves (2.45 GHz) for 2 minutes at an output of 500 W, and then microwaves (2 for 2 minutes at 200 W). .45 GHz) was applied to cure the acid curable resin (a).
After the irradiation, the mold making mold (α) was taken out from the microwave generator, and when 10 minutes passed from the start of kneading, the test piece was taken out from the mold making mold (α) (molding time 10 minutes).
About the obtained test piece, the compressive strength after the lapse of 10 minutes, 30 minutes, 1 hour, 3 hours and 24 hours from the start of kneading was measured. The results are shown in Table 2.

[Example 5]
Xylene sulfonic acid, lactic acid, methanol and water were mixed in a mass ratio (xylene sulfonic acid: lactic acid: methanol: water) = 15: 25: 5: 55 to prepare an aqueous curing agent solution.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution was used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.
A test piece was produced in the same manner as in Example 4 except that the obtained sand composition was used, and the compressive strength was measured. The results are shown in Table 2.

[Example 6]
Xylene sulfonic acid, lactic acid, methanol and water were mixed in a mass ratio (xylene sulfonic acid: lactic acid: methanol: water) = 30: 0: 5: 65 to prepare an aqueous curing agent solution.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution was used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.
A test piece was produced in the same manner as in Example 4 except that the obtained sand composition was used, and the compressive strength was measured. The results are shown in Table 2.

[Comparative Example 1]
Sulfuric acid: xylene sulfonic acid, lactic acid, methanol and water are mixed in a mass ratio (sulfuric acid: xylene sulfonic acid: lactic acid: methanol: water) = 28.8: 22.8: 6: 8.5: 33.9 Then, an aqueous curing agent solution was prepared.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution was used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.

A portion of the obtained sand composition was immediately filled into a test piece production wooden mold in which four cylindrical molds having an inner diameter of 50 mm and a height of 50 mm were formed under the conditions of a temperature of 25 ° C. and a humidity of 50%. The test piece was taken out from the wooden mold after 30 minutes from the start of kneading (molding time 30 minutes).
About the obtained test piece, the compressive strength was measured after 30 minutes, 1 hour, 3 hours, and 24 hours from the start of kneading. The results are shown in Table 2. In Comparative Example 1, an attempt was made to take out the test piece from the wooden mold 10 minutes after the start of kneading, but the mold could not be removed.

[Comparative Example 2]
Sulfuric acid: xylene sulfonic acid, lactic acid, methanol and water are mixed in a mass ratio (sulfuric acid: xylene sulfonic acid: lactic acid: methanol: water) = 35: 23.4: 3: 9.2: 29.4, An aqueous curing agent solution was prepared.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution was used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.
A test piece was produced in the same manner as in Comparative Example 1 except that the obtained sand composition was used, and the compressive strength was measured. The results are shown in Table 2. In Comparative Example 2, since the test piece could be taken out from the wooden mold 10 minutes after the start of kneading (molding time 10 minutes), the compressive strength 10 minutes after the start of kneading was also measured.

[Comparative Example 3]
A curing agent aqueous solution was prepared in the same manner as in Comparative Example 1.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution and reaction product (d) were used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.
A test piece was produced in the same manner as in Comparative Example 1 except that the obtained sand composition was used, and the compressive strength was measured. The results are shown in Table 2. In Comparative Example 3, an attempt was made to take out the test piece from the wooden mold 10 minutes after the start of kneading, but the mold could not be removed.

[Comparative Example 4]
A curing agent aqueous solution was prepared in the same manner as in Comparative Example 2.
A sand composition was prepared in the same manner as in Example 1 except that the obtained aqueous curing agent solution and reaction product (d) were used. The sulfur atom content is shown in Table 2. Moreover, the pot life was measured about the obtained sand composition. The results are shown in Table 2.
A test piece was produced in the same manner as in Comparative Example 1 except that the obtained sand composition was used, and the compressive strength was measured. The results are shown in Table 2. In Comparative Example 4, since the test piece could be taken out from the wooden mold 10 minutes after the start of kneading (molding time 10 minutes), the compressive strength 10 minutes after the start of kneading was also measured.

  In Table 2, “S / curing agent” in “sulfur atom content” is the sulfur atom content (% by mass) in the curing agent with respect to the total mass of the curing agent. “S / acid curable resin” is the sulfur atom content (parts by mass) in the curing agent with respect to 100 parts by mass of the acid curable resin. “S / Refractory granular material” is an amount (part by mass) relative to 1000 parts by mass of the refractory granular material.

From the results of Table 2, in Examples 4 to 6, although the pot life was longer than that of Comparative Examples 1 to 4, it was possible to remove the mold in a short time.

Claims (10)

  A mold molding mold made of a material that transmits microwaves is filled with a sand mold molding mold composition containing a refractory granular material, an acid curable resin, and a curing agent, and irradiated with microwaves for the mold molding. A method for producing a mold, wherein an acid curable resin contained in a sand composition is cured.   The manufacturing method of the casting_mold | template of Claim 1 whose sulfur atom content in a hardening | curing agent is 1.5-6.0 mass% with respect to the total mass of a hardening | curing agent.   The manufacturing method of the casting_mold | template of Claim 1 or 2 whose sulfur atom content in a hardening | curing agent is 0.8-2.6 mass parts with respect to 100 mass parts of said acid curable resins.   The manufacturing method of the casting_mold | template as described in any one of Claims 1-3 whose sulfur atom content in a hardening | curing agent is 0.07-0.20 mass part with respect to 1000 mass parts of said refractory granular materials. .   The mold production according to any one of claims 1 to 4, wherein a content of water in the mold molding sand composition is 3 to 4 parts by mass with respect to 1000 parts by mass of the refractory granular material. Method. A mold making mold made of a material having a relative dielectric constant (ε _r ) of 7 or less.   The mold for mold making according to claim 6, wherein the material includes glass and polyamide.   The mold for mold making according to claim 6 or 7, which is used in a method for producing a mold having a microwave irradiation step. It is a manufacturing method of the mold for mold making according to any one of claims 6 to 8,
A method for producing a mold for mold making, wherein the mold for mold making is produced by three-dimensional additive manufacturing.   The method for producing a mold according to any one of claims 1 to 5, wherein the mold making mold is a mold making mold according to any one of claims 6 to 8.