Mold-forming binder composition

Abstract

To provide a mold-forming binder composition that can suppress deterioration of the filling properties of the mold-forming composition in a low-temperature environment (e.g., below 5°C) and maintain mold strength. [Solution] It contains a cardanol-modified alkali-phenol resin obtained by polycondensing a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions. A mold-forming binder composition wherein the molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.02 to 0.20.

Description

Technical Field

[0001] The present invention relates to a binder composition for mold making.

Background Art

[0002] A mold making method is known, in which a phenol resin is used as a binder, and the phenol resin is cured with an organic ester, carbon dioxide gas, or amine gas (for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A binder containing an alkaline phenol resin has an increase in viscosity under a low temperature environment (for example, 5° C. or lower), which causes problems such as deterioration of the fluidity and filling property into a mold or the like of a composition for mold making containing the binder and refractory particles. If the filling property of the composition for mold making is poor, irregularities will occur on the surface of the obtained mold, or the surface strength of the mold will decrease, and casting defects such as sand inclusion, burning-on, penetration, drawing, and the like may occur on the obtained casting.

[0005] In order to solve the above problems, it is conceivable to add a large amount of a solvent such as water. However, increasing the amount of solvent will reduce the solid content of the binder, which may cause a decrease in mold strength.

[0006] The present invention provides a binder composition for mold making that can suppress the deterioration of the filling property of a composition for mold making under a low temperature environment (for example, 5° C. or lower) and can maintain mold strength, and a composition for mold making containing the same.

Means for Solving the Problems

[0007] The present invention It contains a cardanol-modified alkali-phenol resin obtained by polycondensing a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions. This is a mold-forming binder composition in which the molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.02 to 0.20. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a mold-forming binder composition that can suppress deterioration of the filling properties of a mold-forming composition in a low-temperature environment (e.g., 5°C or below) and maintain mold strength, and a mold-forming composition containing the same. [Modes for carrying out the invention]

[0009] <Bonding agent composition for mold making> The mold-forming binder composition of this embodiment (hereinafter also simply referred to as the binder composition) is It contains a cardanol-modified alkali-phenol resin obtained by polycondensing a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions. The molar ratio of cardanol to phenol in the aforementioned phenol compound (cardanol / phenol) is 0.02 to 0.20.

[0010] The binder composition of this embodiment can suppress the deterioration of the fillability of the mold-making composition in low-temperature environments (e.g., below 5°C) and maintain mold strength, and provides a binder composition that can do this. The reason why the binder composition of this embodiment exhibits such effects is not entirely clear, but it is thought to be as follows.

[0011] It is believed that the hydrophobic groups of the cardanol-derived structural units are oriented at the gas-liquid interface, lowering surface tension. At the same time, they strongly interact with the phenol-derived structural units through π-π stacking, reducing intermolecular friction. This is thought to suppress the deterioration of the fillability of the mold-forming composition at low temperatures.

[0012] [Cardanol-modified alkali phenol resin] The cardanol-modified alkali-phenol resin is obtained by polycondensation of a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions. As the aldehyde compound, one or more types of formaldehyde, acetaldehyde, furfural, glyoxal, etc., can be used. These compounds can be used as aqueous solutions as needed.

[0013] Cardanol is a component found in the shell of cashew nuts and is a compound represented by the following general formula (1). [ka] (In the above general formula (1), R is -(CH2) 14 CH3, -(CH2)6CH=CH(CH2)6CH3, -(CH2)6CH=CHCH2CH=CH(CH2)3CH3, or -(CH2)6CH=CHCH2CH=CH(CH2)2CH=CH2.

[0014] The molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.02 or higher, preferably 0.03 or higher, more preferably 0.05 or higher, and even more preferably 0.08 or higher, from the viewpoint of improving the fillability of the mold-making composition in a low-temperature environment. The molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.20 or lower, preferably 0.18 or lower, more preferably 0.15 or lower, even more preferably 0.12 or lower, even more preferably 0.10 or lower, even more preferably 0.08 or lower, and even more preferably 0.07 or lower, from the viewpoint of suppressing a decrease in mold strength or improving mold strength. Furthermore, the molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is preferably 0.05 to 0.18 and more preferably 0.08 to 0.15 from the viewpoint of improving the fillability of the mold-making composition in a low-temperature environment, while from the viewpoint of suppressing the decrease in mold strength or improving mold strength, it is preferably 0.02 to 0.15, more preferably 0.02 to 0.12, even more preferably 0.02 to 0.10, even more preferably 0.02 to 0.08, and even more preferably 0.03 to 0.07.

[0015] The phenol compound may include phenol and cardanol-based phenol compounds to the extent that it does not impair the effects of the present invention. Examples of phenol compounds other than phenol and cardanol include bisphenol A, bisphenol F, cresol, 3,5-xylenol, resorcinol, catechol, nonylphenol, p-tert-butylphenol, isopropenylphenol, phenylphenol, and other substituted phenols. From the viewpoint of improving the fillability of the mold-making composition in a low-temperature environment and suppressing the reduction of mold strength, the total content of phenol and cardanol in the phenol compound is preferably 80% by mass or more, more preferably substantially 100% by mass, and even more preferably 100% by mass. In this specification, "substantially" means that an amount equivalent to an impurity may be included.

[0016] Examples of alkali catalysts used in the synthesis of the cardanol-modified alkali phenol resin include alkali metal hydroxides such as LiOH, NaOH, and KOH, with NaOH and / or KOH being particularly preferred. Alternatively, these alkali catalysts may be mixed with the binder composition. The alkali metal hydroxide is preferably used in an amount of 0.01 to 6 moles, more preferably 0.5 to 2.5 moles, per mole of phenol.

[0017] Generally, the cardanol-modified alkali phenol resin is used in aqueous solution form. The content of the cardanol-modified alkali phenol resin in the aqueous solution of the cardanol-modified alkali phenol resin (solid mass after drying the aqueous solution of the cardanol-modified alkali phenol resin at 105°C for 3 hours) is preferably 30% by mass or more, and more preferably 50% by mass or more, from the viewpoint of improving mold strength. The content of the cardanol-modified alkali phenol resin in the aqueous solution of the cardanol-modified alkali phenol resin is preferably 85% by mass or less, and more preferably 75% by mass or less, from the viewpoint of improving mold strength and workability. Furthermore, the content of the cardanol-modified alkali phenol resin in the aqueous solution of the cardanol-modified alkali phenol resin is preferably 30 to 85% by mass, and more preferably 50 to 75% by mass, from the viewpoint of improving mold strength and workability.

[0018] From the viewpoint of improving mold strength, the weight average molecular weight (Mw) of the cardanol-modified alkaline phenolic resin is preferably 500 or more, more preferably 800 or more, and still more preferably 1200 or more. From the viewpoints of improving mold strength and improving workability, the weight average molecular weight (Mw) of the cardanol-modified alkaline phenolic resin is preferably 8000 or less, more preferably 5000 or less, and still more preferably 3000 or less. Further, from the viewpoints of improving mold strength and improving workability, the weight average molecular weight (Mw) of the cardanol-modified alkaline phenolic resin is preferably 500 to 8000, more preferably 800 to 5000, and still more preferably 1200 to 3000. The weight average molecular weight of the cardanol-modified alkaline phenolic resin is measured by the method described in the examples.

[0019] From the viewpoint of improving mold strength, the content of the cardanol-modified alkaline phenolic resin in the binder composition is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and even more preferably 35% by mass or more. From the viewpoints of suppressing thickening of the binder composition during storage and improving the fluidity of the molding composition, the content of the cardanol-modified alkaline phenolic resin in the binder composition is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 55% by mass or less, and even more preferably 50% by mass or less. Further, from the viewpoints of improving mold strength, suppressing thickening of the binder composition during storage, and improving the fluidity of the molding composition, the content of the cardanol-modified alkaline phenolic resin in the binder composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, still more preferably 30 to 60% by mass, even more preferably 35 to 60% by mass, still even more preferably 35 to 55% by mass, and still even more preferably 35 to 50% by mass.

[0020] [Water] The binder composition may further contain water. From the viewpoints of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition, the content of water in the binder composition is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, and even more preferably 30% by mass or more. From the viewpoints of improving mold strength, suppressing thickening of the binder composition during storage, and improving the fluidity of the mold-making composition, the content of water in the binder composition is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 55% by mass or less, and even more preferably 50% by mass or less. Furthermore, from the viewpoints of suppressing thickening of the binder composition during storage, improving the fluidity of the mold-making composition, and improving mold strength, the content of water in the binder composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, still more preferably 25 to 55% by mass, and even more preferably 30 to 50% by mass.

[0021] The mass ratio of the cardanol-modified alkaline phenolic resin to water in the binder composition (mass of water / mass of cardanol-modified alkaline phenolic resin) is preferably 0.3 or more, more preferably 0.4 or more, and still more preferably 0.5 or more, from the viewpoints of suppressing thickening of the binder composition during storage and improving the fluidity of the mold-making composition. The mass ratio of the cardanol-modified alkaline phenolic resin to water in the binder composition is preferably 1.5 or less, more preferably 1.3 or less, and still more preferably 1.2 or less, from the viewpoints of improving mold strength, suppressing thickening of the binder composition during storage, and improving the fluidity of the mold-making composition. Furthermore, the mass ratio of the cardanol-modified alkaline phenolic resin to water in the binder composition is preferably 0.3 to 1.5, more preferably 0.4 to 1.3, and still more preferably 0.5 to 1.2, from the viewpoints of suppressing thickening of the binder composition during storage, improving the fluidity of the mold-making composition, and improving mold strength.

[0022] [Other Components] The binder composition may further contain additives such as silane coupling agents, aluminates, and oxyanion compounds, to an extent that does not hinder the effects of this embodiment.

[0023] [Silane coupling agent] The binder composition preferably contains a silane coupling agent from the viewpoint of improving mold strength. Examples of the silane coupling agent include γ-(2-amino)propylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane. The content of the silane coupling agent in the binder composition is preferably 0.1 to 5% by mass, more preferably 0.3 to 1% by mass, from the viewpoint of improving mold strength.

[0024] [Aluminate] The binder composition preferably contains an aluminate from the viewpoint of improving mold strength. Examples of the aluminate include alkali metal salts of aluminic acid. From the viewpoint of improving mold strength, sodium aluminate is preferred. From the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. From the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. Furthermore, from the viewpoint of improving mold strength, the content of the aluminate in the binder composition is preferably 0.1 to 10% by mass, more preferably 0.5 to 5% by mass, and even more preferably 1 to 3% by mass.

[0025] [Oxyanionic compounds] When curing the binder composition with carbon dioxide, it is preferable to include an oxyanion compound from the viewpoint of improving mold strength and improving the curing speed of the mold. This is because it is thought that the oxyanion compound forms an ionomer and polymerizes the cardanol-modified alkali phenol resin only after absorbing carbon dioxide. Examples of the oxyanion compound include boric acid and borate compounds. Examples of borates include sodium tetraborate decahydrate (borax), potassium tetraborate decahydrate, sodium metaborate, sodium pentaborate, and potassium pentaborate. From the viewpoint of improving mold strength and improving the curing speed of the mold, sodium tetraborate decahydrate (borax) is preferred.

[0026] The content of the oxyanion compound in the binder composition is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and even more preferably 6% by mass or more, from the viewpoint of improving mold strength and improving the curing speed of the mold. The content of the oxyanion compound in the binder composition is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and even more preferably 10% by mass or less, from the viewpoint of improving mold strength and improving the fluidity of the mold-making composition. Furthermore, the content of the oxyanion compound in the binder composition is preferably 1 to 30% by mass, more preferably 3 to 20% by mass, even more preferably 5 to 15% by mass, and even more preferably 6 to 10% by mass, from the viewpoint of improving mold strength, improving the curing speed of the mold and improving the fluidity of the mold-making composition.

[0027] <Method for producing a binder composition for mold making> The method for producing the mold-forming binder composition of this embodiment comprises the steps of: obtaining a cardanol-modified alkali-phenol resin by polycondensing a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions; and preparing a mold-forming binder composition containing the cardanol-modified alkali-phenol resin, wherein the molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.02 to 0.20. The preferred range of the mold-forming binder composition in the method for producing the mold-forming binder composition is the same as that of the mold-forming binder composition described above, so no further explanation is provided.

[0028] <Method for manufacturing molds> In the mold manufacturing method of this embodiment, the mold can be manufactured by using the conventional mold manufacturing process as is. A preferred mold manufacturing method includes a mixing step of mixing at least refractory particles and the binder composition to obtain a mold-forming composition, and a curing step of filling the mold-forming composition into a mold and curing the mold-forming composition.

[0029] [Mixing process] [Fire-resistant particles] The refractory particles usable in the mold manufacturing method of this embodiment include conventionally known materials such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, synthetic mullite sand, and alumina ball sand. Recycled sand obtained by recovering and recycling used refractory particles can also be used. The refractory particles can be used individually or in combination of two or more types.

[0030] The average particle size of the refractory particles is preferably greater than 50 μm, more preferably 70 μm or more, even more preferably 120 μm or more, and even more preferably 150 μm or more, from the viewpoint of improving mold strength and economic efficiency. From the same viewpoint, it is preferably 600 μm or less, more preferably 400 μm or less, even more preferably 300 μm or less, and even more preferably 250 μm or less. In this specification, the average particle size is measured by the method described in the examples.

[0031] In the aforementioned mixing process, known methods can be used to mix each raw material. For example, methods include adding and kneading each raw material using a batch mixer, or supplying each raw material to a continuous mixer and kneading it.

[0032] The ratio of the refractory particles to the binder composition can be set as appropriate, but from the viewpoint of improving mold strength and economic efficiency, the content of the binder composition per 1000 parts by mass of the refractory particles is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less. Furthermore, per 1000 parts by mass of the refractory particles, the cardanol-modified alkali phenol resin is preferably 3 parts by mass or more, more preferably 5 parts by mass or more, preferably 80 parts by mass or less, even more preferably 50 parts by mass or less, even more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less.

[0033] [Curing process] In the curing step, the mold-forming composition is packed into a mold and cured. A commonly known method can be used to cure the mold-forming composition. One method for curing the mold-forming composition is curing it with a curing agent. Examples of curing agents include organic ester compounds and carbon dioxide.

[0034] As the aforementioned organic ester compounds, lactones having 3 to 10 carbon atoms, organic esters derived from monohydric or polyhydric alcohols having 1 to 10 carbon atoms and organic carboxylic acids having 1 to 10 carbon atoms, or alkylene carbonates having 1 to 8 carbon atoms can be used alone or in combination. In the self-hardening mold molding method, it is preferable to use γ-butyrolactone, propionactone, ε-caprolactone, ethyl formate, ethylene glycol diacetate, ethylene glycol monoacetate, triacetin, ethylene carbonate, propylene carbonate, etc.

[0035] When an organic ester is used as the curing agent, the amount of the organic ester is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 35 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the binder composition, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0036] When an organic ester is used as the curing agent, the amount of organic ester is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and more preferably 70 parts by mass or less, and more preferably 60 parts by mass or less, per 100 parts by mass of cardanol-modified alkali phenol resin, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0037] When carbon dioxide is used as the curing agent, the flow rate of the carbon dioxide should be such that, from the viewpoint of improving the strength of the mold, the mold is 100 cm 3 The flow rate is preferably 0.2 L / min or more, more preferably 1 L / min or more, even more preferably 5 L / min or more, even more preferably 10 L / min or more, and even more preferably 15 L / min or more, and from the viewpoint of economy, a mold of 100 cm 3 The flow rate is preferably 30 L / min or less, more preferably 25 L / min or less. The carbon dioxide flow time is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 25 seconds or more, from the viewpoint of improving mold strength, and preferably 90 seconds or less, more preferably 70 seconds or less, even more preferably 50 seconds or less, and even more preferably 40 seconds or less, from the viewpoint of economic efficiency. The curing temperature is preferably -5°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher, from the viewpoint of improving mold strength, and preferably 45°C or lower, more preferably 40°C or lower, and even more preferably 35°C or lower, from the viewpoint of economic efficiency.

[0038] When carbon dioxide is used as the curing agent, the amount of carbon dioxide is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and preferably 100 parts by mass or less, and more preferably 75 parts by mass or less, per 100 parts by mass of the binder composition, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0039] When carbon dioxide is used as the curing agent, the amount of carbon dioxide is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, and more preferably 200 parts by mass or less, and more preferably 150 parts by mass or less, per 100 parts by mass of cardanol-modified alkali phenol resin, from the viewpoint of improving mold strength, improving curing speed, and economic efficiency.

[0040] <Mold making composition> The mold-making composition of this embodiment contains the refractory particles and the binder composition. That is, the mold-making composition of this embodiment contains the refractory particles and the cardanol-modified alkali phenol resin.

[0041] The content of the binder composition is as described in the mixing step of the mold manufacturing method with respect to the refractory particles.

[0042] The content of the cardanol-modified alkali phenol resin is as described in the mixing step of the mold manufacturing method with respect to the refractory particles. [Examples]

[0043] The following describes specific examples illustrating the present invention.

[0044] <Method for evaluating raw materials> [Weight-average molecular weight (Mw) of cardanol-modified alkali phenol resin and alkali phenol resin] The weight-average molecular weight (Mw) of cardanol-modified alkali phenol resins, etc., was measured by GPC (gel permeation chromatography) under the following conditions. (a) Sample preparation: An equal weight of deionized water was added to the sample, and neutralization was performed by adding 0.1% by mass of H2SO4. The resulting precipitate was filtered, washed with water, and dried. This was dissolved in tetrahydrofuran (THF) to prepare the sample for GPC. (b) Columns: One Guard Column TSX (manufactured by Toyo Soda Industries Co., Ltd.) HXL (6.5 mmφ × 4 cm), one TSK3000HXL (7.8 mmφ × 30 cm), and one TSK2500HXL (7.8 mmφ × 30 cm) were used. The columns were connected in the order of Guard Column TSX HXL - TSK3000HXL - TSK2500HXL from the injection port side. (c) Standard material: Monodisperse polystyrene with known weight-average molecular weight (manufactured by Toyo Soda Co., Ltd.) (d) Eluent: THF (flow rate: 1cm 3 / min) (e) Column temperature: 25℃ (f) Detector: Ultraviolet spectrophotometer (quantification at the wavelength of the maximum peak of ultraviolet absorption of phenol) (g) Splitting method for molecular weight calculation: Time splitting (2 sec)

[0045] [Average particle size] (For particles larger than 53 μm) Based on the method specified in Annex 2 of JIS Z2601 (1993) "Test Methods for Foundry Sand," measurements were taken using sieves of 850, 600, 425, 300, 212, 150, 106, 75, and 53 μm, and the particle size at 50% mass accumulation was taken as the average particle size. (For particles smaller than 53 μm) This is the average particle diameter at 50% volume cumulative, measured using a laser diffraction particle size distribution analyzer (LA-920, Horiba, Ltd.). The analysis conditions are as follows: • Measurement method: Flow method • Dispersion medium: Ion-exchanged water • Dispersion method: stirring, built-in ultrasonic for 3 minutes • Sample concentration: 2 mg / 100 cc

[0046] <Preparation of cardanol-modified alkali phenol resin A aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 309.6 g of phenol, 34.4 g of cardanol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of cardanol-modified alkali phenol resin A. The content (solid content concentration) of cardanol-modified alkali phenol resin A in the aqueous solution was 65.6% by mass. The weight-average molecular weight (Mw) of the cardanol-modified alkali phenol resin A was 2371.

[0047] <Preparation of cardanol-modified alkali phenol resin B aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 275.2 g of phenol, 68.8 g of cardanol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of cardanol-modified alkali phenol resin B. The content (solid content concentration) of cardanol-modified alkali phenol resin B in the aqueous solution was 65.6% by mass. The weight-average molecular weight (Mw) of the cardanol-modified alkali phenol resin B was 2148.

[0048] <Preparation of cardanol-modified alkali phenol resin C aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 240.8 g of phenol, 103.2 g of cardanol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of cardanol-modified alkali phenol resin C. The content (solid content concentration) of cardanol-modified alkali phenol resin C in the aqueous solution was 65.6% by mass. The weight-average molecular weight (Mw) of the cardanol-modified alkali phenol resin C was 2210.

[0049] <Preparation of cardanol-modified alkali phenol resin D aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 172.0 g of phenol, 172.0 g of cardanol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of cardanol-modified alkali phenol resin D. The content (solid content concentration) of cardanol-modified alkali phenol resin D in the aqueous solution was 65.6% by mass. The weight-average molecular weight (Mw) of the cardanol-modified alkali phenol resin D was 2350.

[0050] <Preparation of cardanol-modified alkali phenol resin E aqueous solution> In a 2-liter glass container equipped with a thermometer and stirrer, 337.1 g of phenol, 6.9 g of cardanol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of cardanol-modified alkali phenol resin E. The content (solid content concentration) of cardanol-modified alkali phenol resin E in the aqueous solution was 65.6% by mass. The weight-average molecular weight (Mw) of the cardanol-modified alkali phenol resin E was 2180.

[0051] <Preparation of an aqueous solution of alkali phenolic resin A> In a 2-liter glass container equipped with a thermometer and stirrer, 344.0 g of phenol, 128.3 g of 48% potassium hydroxide aqueous solution, 242.4 g of water, and 238.7 g of 92% paraformaldehyde were mixed and reacted at 80°C to obtain an aqueous solution of alkali phenol resin A. The content (solid content concentration) of alkali phenol resin A in the aqueous solution of alkali phenol resin A was 65.6% by mass. The weight-average molecular weight (Mw) of alkali phenol resin A was 2176.

[0052] Table 1 shows the proportions of each cardanol-modified alkali phenol resin used in the preparation of the aforementioned materials.

[0053] [Table 1]

[0054] <Examples and Comparative Examples> [Example 1 (Preparation of binder composition)] A binder composition according to Example 1 was obtained using 53.0% by mass of the cardanol-modified alkali phenol resin A aqueous solution (34.7% by mass of cardanol-modified alkali phenol resin), 26.4% by mass of a 48% by mass potassium hydroxide aqueous solution, 10.5% by mass of triethylene glycol monoethyl ether, 2.9% by mass of a 50% by mass sodium aluminate aqueous solution, 6.5% by mass of sodium tetraborate decahydrate (borax), and 0.7% by mass of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent. The composition of the binder composition according to Example 1 is shown in Table 2.

[0055] [Examples 2 and 3 (Preparation of binder composition)] The procedure was carried out in the same manner as in Example 1, except that cardanol-modified alkali phenol resin B or C was used, to obtain the binder compositions according to Examples 2 and 3. The compositions of the binder compositions according to Examples 2 and 3 are shown in Table 2.

[0056] [Example 4 (Preparation of binder composition)] A binder composition according to Example 4 was obtained using 67.5% by mass of the cardanol-modified alkali phenol resin A aqueous solution (44.3% by mass of cardanol-modified alkali phenol resin), 9.2% by mass of a 48% by mass sodium hydroxide aqueous solution, 22.3% by mass of water, 0.2% by mass of a 50% by mass sodium aluminate aqueous solution, and 0.8% by mass of 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent. The composition of the binder composition according to Example 4 is shown in Table 3.

[0057] [Comparative Example 1 (Preparation of a binder composition)] The procedure was carried out in the same manner as in Example 1, except that alkali phenol resin A was used, to obtain a binder composition according to Comparative Example 1. The composition of the binder composition according to Comparative Example 1 is shown in Table 2.

[0058] [Comparative Examples 2 and 3 (Preparation of Binding Agent Compositions)] The procedure was carried out in the same manner as in Example 1, except that cardanol-modified alkali phenol resin D or E was used, to obtain the binder compositions for Comparative Examples 2 and 3. The compositions of the binder compositions for Comparative Examples 2 and 3 are shown in Table 2.

[0059] [Comparative Example 4 (Preparation of a binder composition)] The procedure was carried out in the same manner as in Example 4, except that the alkali phenol resin A was used, to obtain the binder composition according to Comparative Example 4. The composition of the binder composition according to Comparative Example 4 is shown in Table 3.

[0060] <Evaluation Method> [Examples 1-3, Comparative Examples 1-3] [Evaluation of filling properties] Under conditions of 5°C and 55% RH, 1000 parts by mass of refractory particles cooled to 5°C and 30 parts by mass of the binder composition were added to a kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade. The mixture was then mixed at a rotation speed of 300 rpm for 2 minutes to obtain a mold-making composition. The obtained mold-making composition was filled into a 50 mmΦ × 300 mm test tube from the top to the top of the tube, and the mass was measured. A larger mass value indicates better filling performance. The refractory particles used were silica sand ("Mikawa Silica Sand R Grade No. 6," manufactured by Mikawa Silica Co., Ltd.). The average particle size of the refractory particles was 181 μm. The evaluation results are shown in Table 2.

[0061] [Evaluation of mold strength] Under conditions of 5°C and 55%RH, 1000 parts by mass of refractory particles cooled to 5°C and 30 parts by mass of the binder composition were added to a kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade, and mixed at a rotation speed of 300 rpm for 2 minutes to obtain a mold-making composition. The obtained mold-making composition was filled into a wooden mold for a test piece measuring 50 mmΦ × 50 mm, and carbon dioxide gas was passed through it at a flow rate of 20 L / min at 25°C for 30 seconds to obtain an evaluation test piece. After 30 seconds had elapsed since carbon dioxide gas passage, the mold compressive strength of the test piece was measured using a compressive strength evaluation tester ("SDW-020F" Imada Seisakusho Co., Ltd.) at a speed of 5 mm / min. The evaluation results are shown in Table 2.

[0062] [Table 2]

[0063] [Example 4, Comparative Example 4] [Evaluation of filling properties] Under conditions of 5°C and 55% RH, 1000 parts by mass of refractory particles cooled to 5°C, 15 parts by mass of the binder composition, and 3.0 parts by mass of triacetin were added to a kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade. The mixture was then mixed at a rotation speed of 300 rpm for 2 minutes to obtain a mold-making composition. The obtained mold-making composition was filled into a 50 mmΦ × 300 mm test tube from the top to the top of the tube, and the mass was measured. A larger mass value indicates better filling performance. The refractory particles used were silica sand ("Mikawa Silica Sand R Grade No. 6," manufactured by Mikawa Silica Co., Ltd.). The average particle size of the refractory particles was 181 μm. The evaluation results are shown in Table 3.

[0064] [Evaluation of mold strength] Under conditions of 5°C and 55% RH, 1000 parts by mass of refractory particles cooled to 5°C, 15 parts by mass of the binder composition, and 3.0 parts by mass of triacetin were placed in a kitchen mixer "Kenmix Aiko Chef" (manufactured by Aikosha Seisakusho Co., Ltd.) equipped with an aluminum beater stirring blade, and mixed at a rotation speed of 300 rpm for 2 minutes to obtain a mold-making composition. The obtained mold-making composition was filled into a wooden mold for a test piece measuring 50 mmΦ × 50 mm, and left to stand at 25°C for 30 minutes to obtain an evaluation test piece. The test piece was evaluated using a compression strength evaluation tester ("SDW-020F" manufactured by Imada Seisakusho Co., Ltd.) at a speed of 5 mm / min, and the mold compression strength of the test piece was measured. The evaluation results are shown in Table 3.

[0065] [Table 3]

Claims

1. It contains a cardanol-modified alkali-phenol resin obtained by polycondensing a phenol compound containing phenol and cardanol with an aldehyde compound under alkaline conditions. A mold-forming binder composition wherein the molar ratio of cardanol to phenol in the phenol compound (cardanol / phenol) is 0.02 to 0.

20.

2. The mold-forming binder composition according to claim 1, wherein it contains water and the mass ratio of the cardanol-modified alkali phenol resin to the water (mass of water / mass of cardanol-modified alkali phenol resin) is 0.3 to 1.

5.

3. The mold-forming binder composition according to claim 1, wherein the content of the cardanol-modified alkali phenol resin in the mold-forming binder composition is 10% by mass or more and 70% by mass or less.

4. A mold-making composition containing a mold-making binder composition and refractory particles according to any one of claims 1 to 3.

5. A method for manufacturing a mold, comprising a mixing step of mixing refractory particles and a mold-forming binder composition according to any one of claims 1 to 3 to obtain a mold-forming composition, and a curing step of filling a mold-forming composition into a mold and curing the mold-forming composition.

6. The method for producing a mold according to claim 5, wherein the curing agent used to cure the mold-making composition in the curing step is an organic ester compound or carbon dioxide.

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