JP7316137B2 - Binder composition for mold making - Google Patents

Description

The present invention relates to a binder composition for mold making.

In general, an acid-curable mold is prepared by combining refractory particles such as silica sand with a binder composition for mold molding containing an acid-curable resin and a curing agent composition containing sulfonic acid, sulfuric acid, phosphoric acid, or the like. After adding and kneading these, the resulting kneaded sand is filled in a master such as a wooden mold, and the acid-curable resin is cured to produce the product. Furan resins and phenolic resins are used as acid-curable resins. Furan resins include furfuryl alcohol, furfuryl alcohol-urea-formaldehyde resin, furfuryl alcohol-formaldehyde resin, furfuryl alcohol-phenol- Formaldehyde resin and other known modified furan resins are used. This method of manufacturing molds allows for a highly flexible molding operation, and because the molds have excellent thermal properties, high-quality castings can be produced. It is widely used in casting castings of

Furfuryl alcohol is used as a component of acid-curable resins and furan resins, and is an important key material. Therefore, agents that can replace furfuryl alcohol are being investigated.

As an agent that can replace furfuryl alcohol, saccharides have been studied because furfuryl alcohol is produced from C5 sugar, which is the main component of the core of corn (for example, Patent Document 1).

Chinese Patent Application Publication No. 102861867

However, conventional binder compositions containing sugar intended to replace furfuryl alcohol have the problem of reduced mold strength.

INDUSTRIAL APPLICABILITY The present invention provides a binder composition for mold making, which can maintain mold strength even when a part of furfuryl alcohol is replaced.

The binding agent composition for mold molding of the present invention contains a furan resin and triacetin.

ADVANTAGE OF THE INVENTION According to this invention, the binder composition for mold making which can maintain mold intensity|strength can be provided, even if it substitutes a part of furfuryl alcohol.

<Binder composition for mold making>
The binding agent composition for mold molding of the present embodiment (hereinafter also simply referred to as the binding agent composition) contains a furan resin and triacetin. According to the binder composition of the present embodiment, it is possible to provide a binder composition for mold making that can maintain mold strength even when furfuryl alcohol is partly replaced. Although the reason why the binding agent composition of the present embodiment exhibits such an effect is not clear, it is considered as follows.

Triacetin, which is acetylated glycerin, is less soluble in water than glycerin and soluble in furfuryl alcohol. This is because acetylating the hydroxyl group of glycerin increases compatibility with furan resin and promotes homogenization, and local weak points are reduced compared to blending glycerin, so furfuryl As a furan resin in which alcohol or the like is used, it is thought that the mold strength can be improved.

[Triacetin]
The binding agent composition for mold molding of the present embodiment contains triacetin from the viewpoint of maintaining mold strength even when furfuryl alcohol is substituted.

The content of triacetin in the binder composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, from the viewpoint of reducing the content of furfuryl alcohol and improving supply stability. % or more by mass is more preferable. The content of triacetin in the binder composition is preferably 40% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, and 12% by mass or less, from the viewpoint of expressing high mold strength. is still more preferable, and 10% by mass or less is even more preferable. Further, the content of triacetin in the binder composition is preferably 0.1 to 40% by mass, more preferably 1 to 20% by mass, and even more preferably 3 to 15% by mass, based on the above viewpoints. , more preferably 3 to 12% by mass, and even more preferably 3 to 10% by mass.

[Furan resin]
The furan resin includes furfuryl alcohol, condensates of furfuryl alcohol, condensates of furfuryl alcohol and aldehydes, condensates of furfuryl alcohol, urea and aldehydes (urea-modified furan resins), urea, ethylene urea and aldehydes. Condensates (urea/ethylene urea cocondensation resins), condensates of melamine and aldehydes, and condensates of urea and aldehydes, or 2 selected from these groups A mixture of more than one species can be exemplified. A cocondensate of two or more selected from these groups can also be used. Among these, one or more selected from furfuryl alcohol, condensates of furfuryl alcohol, condensates of furfuryl alcohol, urea and aldehydes, and cocondensation thereof, from the viewpoint of improving the curing speed of the mold and improving the mold strength. I prefer to use things.

The monomer composition used for synthesizing the furan resin contains furfuryl alcohol, and one or more monomers selected from, for example, aldehydes, urea, phenols, and melamine are selected depending on the desired condensate. available and available.

Examples of the aldehydes include formaldehyde, acetaldehyde, glyoxal, furfural, terephthalaldehyde, hydroxymethylfurfural and the like, and one or more of these can be used as appropriate. From the viewpoint of improving mold strength, it is preferable to use formaldehyde, and from the viewpoint of reducing the amount of formaldehyde generated during molding, it is preferable to use furfural, terephthalaldehyde, and hydroxymethylfurfural.

Examples of the phenols include phenol, cresol, resorcinol, bisphenol A, bisphenol C, bisphenol E and bisphenol F, and one or more of these can be used.

When producing a condensate of furfuryl alcohol and aldehydes, it is preferable to use 0.01 to 1 mol of aldehydes per 1 mol of furfuryl alcohol. Further, when producing a condensate of furfuryl alcohol, aldehydes and urea, 0.05 to 3 mol of aldehydes and 0.03 to 1.5 mol of urea are used per 1 mol of furfuryl alcohol. preferably.

The reaction temperature for synthesizing the furan resin varies depending on the raw materials used, and the viscosity of the resulting binder composition, the amount of residual aldehyde, the shortening of the production time, the prevention of the runaway reaction of the furan resin, and the evaporation of the raw materials. From the point of view, 50 to 150°C is preferable, 70 to 130°C is more preferable, and 80 to 130°C is even more preferable. From the same point of view, the reaction time for synthesizing the furan resin is preferably 0.5 to 12 hours, more preferably 1 to 10 hours, and even more preferably 3 to 8 hours.

When furan resin is produced, furan resin, raw material furfuryl alcohol, water contained in the raw material, water generated during the reaction, and the like are included, but they do not have to be removed from the viewpoint of economy. The furan resin composition contains furan resin, furfuryl alcohol and components other than furan resin, such as water.

From the viewpoint of improving mold strength, the content of the furan resin in the binder composition is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 68% by mass or more, and 72% by mass or more. Even more preferred. From the viewpoint of viscosity reduction, the content of the furan resin in the binder composition is more preferably 98% by mass or less, and even more preferably 95% by mass or less. Further, the content of the furan resin in the binder composition is preferably 50 to 98% by mass, more preferably 60 to 95% by mass, more preferably 68 to 95% by mass, from the viewpoint of improving mold strength and reducing viscosity. is more preferred, and 72 to 95% by mass is even more preferred.

[Curing accelerator]
The binder composition of the present embodiment may contain a curing accelerator from the viewpoint of improving mold strength. Specific examples and amounts of curing accelerators are described in International Publication 2015/098642.

<Water>
The binder composition may further contain water. For example, when synthesizing various condensates such as a condensate of furfuryl alcohol and aldehydes, the condensate is usually in the form of a mixture with water, since aqueous raw materials are used or condensation water is produced. is obtained by When using such a condensate in a binder composition, water may be removed by topping or the like as necessary, but it is necessary to remove water during production as long as the curing reaction rate can be maintained. no. Further, water may be further added for the purpose of adjusting the viscosity of the binder composition so that it is easy to handle. When water is further added for the purpose of adjusting the viscosity of the binder composition to be easy to handle, the content of water in the binder composition is preferably 0.5% by mass or more, more preferably 1% by mass or more. , more preferably 3% by mass or more. However, from the viewpoint of maintaining the curing reaction rate, the content of water in the binder composition is preferably 30% by mass or less, more preferably 25% by mass or less. Further, the content of water in the binder composition is preferably 0.5 to 30% by mass from the viewpoint of adjusting the viscosity of the binder composition to be easy to handle and from the viewpoint of maintaining the curing reaction speed. 1 to 25% by mass is more preferable, and 3 to 25% by mass is even more preferable.

<Other additives>
In addition, the binder composition may further contain an additive such as a silane coupling agent. For example, if the binder composition contains a silane coupling agent, the final strength of the resulting mold can be further improved, which is preferable. Specific examples of silane coupling agents include those described in International Publication 2015/098642. As the silane coupling agent, from the viewpoint of improving the strength of the template, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, Aminosilanes such as N-β-(aminoethyl)-γ-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane are preferred, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane is more preferred.

From the viewpoint of improving the final strength of the mold, the content of the silane coupling agent in the binder composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more. From the same viewpoint, the content of the silane coupling agent in the binder composition is preferably 0.5% by mass or less, more preferably 0.3% by mass or less.

<Mold composition>
The binder composition can be mixed with refractory particles and a hardener composition to form a foundry composition. The foundry composition of the present embodiment contains the binder composition, the refractory particles and the curing agent composition.

[Refractory particles]
As the refractory particles, conventionally known ones such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Recycled materials can also be used.

[Curing agent composition]
The curing agent composition may be used without particular limitation as long as it contains a curing agent that cures the binder composition. Examples of the curing agent include acid-based curing agents such as xylenesulfonic acid (especially m-xylenesulfonic acid), toluenesulfonic acid (especially p-toluenesulfonic acid), sulfonic acid compounds such as methanesulfonic acid, phosphorus One or more of conventionally known substances such as acids, phosphoric acid compounds such as acid phosphate esters, and acidic aqueous solutions containing sulfuric acid and the like can be used. However, if a curing agent composition containing a sulfur-containing acid such as sulfonic acid or sulfuric acid is used, sulfur dioxide gas is generated during casting, so only 2,6-dihydroxybenzoic acid and/or oxalic acid are contained. preferably. In this case, generation of sulfur dioxide gas during casting can be prevented. The content of the sulfur-containing acid in the curing agent composition is preferably 30% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and even more preferably 1% by mass or less.

The content of the curing agent in the curing agent composition is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, from the viewpoint of improving final mold strength.

In the casting composition, 0.5 to 3.0 parts by mass of the binder composition and 0.07 to 2.0 parts by mass of the curing agent composition are contained with respect to 100 parts by mass of the refractory particles. is preferred.

In addition, the content of the curing agent composition in the foundry composition is preferably 0.1 parts by mass or more, more preferably 0.1 part by mass or more, with respect to 1.0 parts by mass of the binder composition from the viewpoint of improving the strength of the mold. is 0.14 parts by mass or more, more preferably 0.2 parts by mass or more, preferably 0.8 parts by mass or less, more preferably 0.6 parts by mass or less, and even more preferably 0.4 parts by mass or less be. Summarizing the above, the content of the curing agent composition in the foundry composition is preferably 0.1 to 0.1 parts per 1.0 part by mass of the binder composition from the viewpoint of improving the strength of the foundry mold. 8 parts by mass, more preferably 0.14 to 0.6 parts by mass, and even more preferably 0.2 to 0.4 parts by mass.

<Mold manufacturing method>
A casting mold can be produced by curing the casting composition of the present embodiment. In the mold manufacturing method of the present embodiment, the mold can be manufactured by using the conventional mold manufacturing process as it is. As a preferred casting mold manufacturing method, the refractory particles, the binder composition for casting molds of the present embodiment, and a curing agent composition for curing the binding agent composition for casting molds are mixed to form a composition for casting molds. and a curing step of filling the mold composition into a mold and curing the mold composition.

The mixing step includes a first mixing step of mixing a refractory granular material and a hardener composition for mold making containing a hardener composition, and adding a binder for mold making to the mixture obtained after the first mixing step. It is preferred to have a second mixing step of mixing the composition.

In the mixing step, an acid-curable resin, a curing accelerator, water, an additive such as a silane coupling agent, an acidic substance, a solvent, and the like may be added to such an extent that the effects of the present embodiment are not impaired.

In the mixing step, as a method for mixing each raw material, a known general method can be used, for example, a method of adding each raw material by a batch mixer and kneading, or a method of supplying each raw material to a continuous mixer and kneading. method.

EXAMPLES Examples and the like specifically showing the present invention will be described below.

<Examples 1 to 3, Comparative Examples 1 to 3>

[Preparation of furan resin composition]
100 parts by mass of furfuryl alcohol, 35 parts by mass of paraformaldehyde and 13 parts by mass of urea were mixed in a three-necked flask and adjusted to pH 9 with a 25% by mass sodium hydroxide aqueous solution. After the temperature of the reaction mixture was raised to 100° C., the reaction was carried out at the same temperature for 1 hour. The pH was adjusted to 4.5 with 37% by mass hydrochloric acid, and the mixture was further reacted at 100° C. for 1 hour. After that, the pH was adjusted to 7 with a 25% by mass sodium hydroxide aqueous solution, 5 parts by mass of urea was added, and the mixture was reacted at 100° C. for 30 minutes to obtain a furan resin composition. The composition of the furan resin composition was 71.7% by mass of urea-modified furan resin, 19.5% by mass of furfuryl alcohol, and 8.8% by mass of water.

[Preparation of Binder Composition for Mold Making]
Using the above furan resin composition, furfuryl alcohol, triacetin or glycerin, water, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane as a silane coupling agent, the composition shown in Table 1 was obtained. to prepare the binder compositions for mold making of Examples 1 to 3 and Comparative Examples 1 to 3. In Table 1, FFA means furfuryl alcohol.

[Manufacture of mold composition]
Under the conditions of 25° C. and 55% RH, 0.32 parts by mass of the curing agent composition was added to 100 parts by mass of furan-regenerated silica sand, and the caking molds of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared. 0.8 parts by mass of the agent composition was added and mixed to obtain a casting composition. As the furan-regenerated silica sand, sand having a mass loss rate (LOI) of 1.9% by mass when heated at 1000° C. for 1 hour in air and a grain size of 38 (AFS) was used. Kao Lightener US-3 and C-21 (both aqueous solutions with xylenesulfonic acid and sulfuric acid) manufactured by Kao Quaker Co., Ltd. are used for the above-mentioned curing agent composition. Tests were carried out by blending in proportions.

[Test example]
The casting composition immediately after kneading was filled in a cylindrical test piece frame with a diameter of 50 mm and a height of 50 mm, and the mold was removed when the compressive strength reached 1 MPa. The compressive strength (MPa) was measured by the method described above, and was defined as "compressive strength after 24 hours". The higher the value of "compressive strength after 24 hours", the better the mold strength. Table 1 shows the results.

From the results in Table 1, it can be seen that Examples 1 to 3 are superior in mold strength to Comparative Examples 1 to 3, respectively.

Claims (4)

A binder composition for mold molding containing furan resin and triacetin ,
A binder composition for mold making, wherein the triacetin content in the binder composition for mold making is 0.1 to 40% by mass. 2. The mold forming caking agent according to claim 1, wherein the furan resin is at least one selected from furfuryl alcohol, condensates of furfuryl alcohol, urea and aldehydes, and condensates of urea, ethylene urea and aldehydes. agent composition. A foundry composition containing refractory particles, the foundry binder composition according to claim 1 or 2 , and a curing agent composition containing a curing agent for curing the foundry binder composition. thing. Refractory particles, the binder composition for mold molding according to claim 1 or 2 , and a curing agent composition containing a curing agent for curing the binder composition for mold molding are mixed to form a mold. A method for producing a casting mold, comprising a mixing step of obtaining a composition, and a curing step of filling the casting composition into a mold and curing the casting composition.