JP7236218B2 - Binder composition for mold making - Google Patents

Description

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

A casting method is known that uses a water-soluble phenol resin as a binder and an ester compound as a curing agent. The mold according to the mold making method has high heat resistance and does not contain elements such as sulfur and phosphorus that deteriorate the casting quality in the binder, so that high-quality castings can be produced (for example, , Patent Document 1).

JP-A-3-291124

However, when a water-soluble phenolic resin is used as a binding agent for a mold, thermal decomposition gas accompanied by a relatively strong odor is generated during casting, which may deteriorate the working environment.

The present invention provides a binder composition for mold making that can suppress deterioration of the working environment during casting using a mold containing a phenol resin as a binder.

The present invention is a binding agent composition for casting molds containing a polymer having a monomer unit represented by the following general formula (1).

（一般式（１）中、ｍ及びｎはそれぞれフェニル基に結合している水酸基の数を示し、０以上、３以下である。但し、ｍ及びｎは同時に０ではない。）

(In general formula (1), m and n each represent the number of hydroxyl groups bonded to a phenyl group, and are 0 or more and 3 or less, provided that m and n are not 0 at the same time.)

The present invention provides a binder composition for mold making, comprising a polymer obtained by reacting a phenol containing an aromatic polyhydric alcohol represented by the following general formula (2) with an aldehyde compound under alkaline conditions. is.

（一般式（２）中、ｍ及びｎはそれぞれフェニル基に結合している水酸基の数を示し、０以上、３以下である。但し、ｍ及びｎは同時に０ではない。）

(In general formula (2), m and n each represent the number of hydroxyl groups bonded to a phenyl group, and are 0 or more and 3 or less, provided that m and n are not 0 at the same time.)

ADVANTAGE OF THE INVENTION According to this invention, even when a phenol resin is used as a binding agent, it can suppress the deterioration of the working environment at the time of casting.

<Binder composition for mold making>
The binding agent composition for mold molding of this embodiment contains a polymer having a monomer unit represented by the following general formula (1).

一般式（１）中、ｍ及びｎはそれぞれフェニル基に結合している水酸基の数を示し、鋳造時の作業環境の悪化を抑制する観点から、それぞれ０以上であり、１以上が好ましく、同様の観点から、３以下であり、２以下が好ましい。また、前記一般式（１）中のｍ及びｎは、同様の観点から、それぞれ０～３であり（但し、ｍ及びｎは同時に０ではない）、１又は２がより好ましい。

In the general formula (1), m and n each indicate the number of hydroxyl groups bonded to the phenyl group, and from the viewpoint of suppressing deterioration of the working environment during casting, each is 0 or more, preferably 1 or more, and the same from the viewpoint of, it is 3 or less, preferably 2 or less. From the same viewpoint, m and n in the general formula (1) are each 0 to 3 (wherein m and n are not 0 at the same time), and 1 or 2 is more preferable.

According to the binding agent composition for mold making of the present embodiment, it is possible to suppress deterioration of working environment during casting when a water-soluble phenol resin is used as a binding agent.

The monomer unit represented by the general formula (1) is a monomer unit derived from an aromatic polyhydric alcohol represented by the following general formula (2).

一般式（２）中、ｍ及びｎはそれぞれフェニル基に結合している水酸基の数を示し、鋳造時の作業環境の悪化を抑制する観点から、それぞれ０以上であり、同様の観点から、３以下であり、２以下が好ましい。また、前記一般式（２）中のｍ及びｎは、同様の観点から、それぞれ０～３であり、１又は２がより好ましい。ただし、ｍ及びｎは同時に０ではない。

In general formula (2), m and n each indicate the number of hydroxyl groups bonded to a phenyl group, and are each 0 or more from the viewpoint of suppressing deterioration of the working environment during casting. or less, preferably 2 or less. Further, m and n in the general formula (2) are each 0 to 3, more preferably 1 or 2, from the same viewpoint. However, m and n are not 0 at the same time.

The aromatic polyhydric alcohol represented by the general formula (2) is the group consisting of phenylphenol, 2,2'-biphenol, and 4,4'-biphenol from the viewpoint of suppressing deterioration of the working environment during casting. One or more selected from among them are preferable, and 2,2'-biphenol is more preferable.

The polymer may be a polymer composed only of the monomer unit represented by the general formula (1), and a monomer other than the monomer unit represented by the general formula (1) within a range that does not impair the effects of the present embodiment. may have units. In the present specification, a polymer composed only of monomer units represented by the general formula (1) is also referred to as a homopolymer, and represented by the general formula (1) within a range that does not impair the effects of the present embodiment. A polymer having monomer units other than monomer units is also called a copolymer-based polymer.

A monomer unit other than the monomer unit represented by the general formula (1) is preferably a monomer unit derived from a water-soluble phenol compound. The water-soluble phenolic compounds include phenol, bisphenol A, bisphenol F, cresol, 3,5-xylenol, resorcinol, catechol, nonylphenol, p-tert-butylphenol, isopropenylphenol, and other water-soluble phenols including substituted phenols. can be exemplified.

[Method for producing polymer]
The said polymer can be manufactured using a well-known method. One example is a method of obtaining a polymer by reacting a phenol containing an aromatic polyhydric alcohol represented by the general formula (2) with an aldehyde compound under alkaline conditions.

When producing the copolymer-based polymer, from the viewpoint of suppressing deterioration of the working environment during casting, the water-soluble phenol compound and 0.1 mol or more, preferably 0.2 mol, per 1 mol of the water-soluble phenol compound It is preferable to react the aromatic polyhydric alcohol represented by the above general formula (2) with an aldehyde compound under alkaline conditions. When producing a polymer having the monomer unit, from the viewpoint of suppressing a decrease in mold strength, the water-soluble phenol compound and the general formula (2) of 50 mol or less, preferably 40 mol or less per 1 mol of the water-soluble phenol compound. It is preferable to react an aromatic polyhydric alcohol represented by with an aldehyde compound under alkaline conditions.

As the aldehyde compound, formaldehyde, furfural, glyoxal and the like can be used singly or in combination of two or more. In addition to these, urea, melamine, monomers that can be condensed with aldehyde compounds such as cyclohexanone, monohydric aliphatic alcohol compounds such as methanol, ethanol, isopropyl alcohol, normal propyl alcohol, butyl alcohol, water-soluble polymers polyacrylic acid salt, cellulose derivative polymer, polyvinyl alcohol, lignin derivative and the like may be mixed.

The alkaline catalyst used in the polycondensation of the aromatic polyhydric alcohol represented by the general formula (2) and the aldehyde compound under alkaline conditions consists of lithium hydroxide, sodium hydroxide, and potassium hydroxide. One or more alkali metal hydroxides selected from the group may be mentioned, and one or more selected from the group consisting of sodium hydroxide and potassium hydroxide is particularly preferable.

From the viewpoint of improving mold strength, the weight average molecular weight (Mw) of the copolymer-based polymer is preferably 300 or more, more preferably 400 or more, preferably 5000 or less, and more preferably 4000 or less. Further, the weight average molecular weight (Mw) of the polymer is preferably 400 to 5000, more preferably 500 to 4000, from the viewpoint of improving mold strength. In this specification, the weight average molecular weight is measured by the method described in Examples.

The homopolymer is composed of the aromatic polyhydric alcohol represented by the general formula (2) and an aqueous alkali hydroxide solution that is 1-fold mol of the aromatic polyhydric alcohol represented by the general formula (2). It can be obtained by mixing and neutralizing the mixture below, adjusting the concentration appropriately, adding aldehyde, and heating to carry out a polycondensation reaction. Aldehydes that can be used in the preparation of the homopolymer are the same as aldehydes that can be used in the preparation of the copolymer.

The weight average molecular weight of the homopolymer is 300 or more, more preferably 400 or more, from the viewpoint of improving mold strength, and is preferably 10,000 or less, more preferably 2,000 from the viewpoint of ease of handling such as fluidity. It is below. Further, the weight average molecular weight of the homopolymer is preferably 300 to 10,000, more preferably 400 to 2,000, from the viewpoint of improving mold strength.

[Confirmation of polymer structure]
The fact that the polymer has a monomer unit represented by the general formula (1) is obtained by analyzing an analysis sample fractionated to a weight average molecular weight of a certain value or less (e.g., 10000 or less) by MALDI-TOF / MS. can be confirmed by

The mold forming binder composition may contain a known phenolic resin. Any known phenolic resin can be used. Specific examples of the known phenolic resins include conventionally known phenolic resins such as novolac resins, resol resins, and water-soluble alkaline phenolic resins, which are suitable for their respective curing systems. Moreover, these phenol resins include resins co-condensed with conventionally known phenols such as cresol and bisphenols such as bisphenol A. Among these, water-soluble alkali phenol resins are preferred.

From the viewpoint of suppressing deterioration of the working environment during casting, the amount of the monomer unit represented by the general formula (1) in the polymer should be It is preferably 0.1 mol or more, more preferably 0.2 mol or more, relative to 1 mol of the total amount of monomer units other than the monomer unit represented by the general formula (1) in coalescing, from the viewpoint of suppressing reduction in mold strength. , is preferably 50 mol or less, more preferably 40 mol or less. In addition, the amount of the monomer unit represented by the general formula (1) in the polymer is adjusted from the viewpoint of suppressing the deterioration of the working environment during casting and from the viewpoint of suppressing the decrease in mold strength. It is preferably from 0.1 to 50 mol, more preferably from 0.2 to 40 mol, per 1 mol of the total amount of the monomer of the phenol compound in the polymer and the amount of the monomer unit in the polymer.

The binding agent composition for mold making may contain phenols including the aromatic polyhydric alcohol represented by the general formula (2). The phenols are preferably one or more selected from the group consisting of phenylphenol, 2,2'-biphenol, and 4,4'-biphenol from the viewpoint of suppressing deterioration of the working environment during casting. 2'-biphenol is more preferred.

The content of the phenols in the binder composition for mold making is not particularly limited, and can be adjusted as appropriate. As an example, the sum of the amount of the aromatic polyhydric alcohol represented by the general formula (2) and the amount of the monomer units represented by the general formula (1) in the polymer is the working environment during casting From the viewpoint of suppressing the deterioration of the is preferably 0.1 mol or more, more preferably 0.2 mol or more, and from the viewpoint of suppressing a decrease in mold strength, it is preferably 50 mol or less, more preferably 40 mol or less. The sum of the amount of the aromatic polyhydric alcohol represented by the general formula (2) and the amount of the monomer unit represented by the general formula (1) in the polymer is phenol in the binder composition From the viewpoint of suppressing the deterioration of the working environment during casting and the strength of the mold, the total amount of 1 mol of the monomer amount of the compound and the amount of the monomer unit other than the monomer unit represented by the general formula (1) in the polymer From the viewpoint of suppressing the decrease, it is preferably 0.1 to 50 mol, more preferably 0.2 to 40 mol, per 1 mol of the total amount of the phenol compound monomer in the binder composition and the monomer unit in the polymer. more preferred.

As a method for adding the phenols to the binder composition for molding molds, there is a method of adding them separately, or an excessive amount of By using it, it can be included as an unreacted product.

[Auxiliary component]
The binding agent composition for mold making may contain additives such as water, silane coupling agents, urea, surfactants, and alcohols to the extent that the effects of the present embodiment are not impaired. In addition, it is preferable that the binding agent composition for mold making contains a silane coupling agent, since the final strength of the resulting mold can be further improved. Examples of the silane coupling agent include γ-(2-amino)propylmethyldimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N- β-(aminoethyl)γ-aminopropylmethyldimethoxysilane and the like. The content of the silane coupling agent in the binder composition for mold making is preferably 0.005 to 3 parts by mass from the viewpoint of improving the mold strength with respect to 100 parts by mass of the binder composition. , 0.01 to 1 part by mass is more preferable.

The binder composition can be obtained by mechanically kneading one or more components using a mixing device.

<Mold manufacturing method>
In the method for producing a mold according to the present embodiment, refractory particles, the binder composition for mold molding, and a curing agent for curing the binder composition for mold molding are mixed to obtain a composition for mold. and a curing step of filling the casting composition into a mold and curing the casting composition. In the mold manufacturing method of the present embodiment, the mold can be manufactured by using the conventional mold manufacturing process as it is.

According to the mold manufacturing method of the present embodiment, it is possible to reduce the odor during casting using the mold containing the phenol resin in the binder composition, and to suppress deterioration of the working environment.

[Mixing process]
[Refractory particles]
As the refractory particles that can be used in the mold manufacturing method of the present embodiment, conventionally known particles such as silica sand, chromite sand, zircon sand, olivine sand, alumina sand, mullite sand, and synthetic mullite sand can be used. Recycled sand obtained by recovering and regenerating used refractory particles can also be used, but reclaimed sand is preferable from the viewpoint of economy and the effect of the mold manufacturing method. The refractory particles can be used alone or in combination of two or more.

[Curing agent]
The curing agent can be used without any particular limitation as long as it cures the binder composition, but an ester compound is preferable from the viewpoint of improving mold strength.

The ester compound is a conventionally known ester compound that can be used as a curing agent for the binder composition. Examples of the ester compound include lactones or organic ester compounds derived from monohydric or polyhydric alcohols having 1 to 10 carbon atoms and organic carboxylic acids having 1 to 10 carbon atoms, either singly or as a mixture.

Specific examples of the ester compounds include propionolactone, ε-caprolactone, ethyl formate, and ethylene glycol monoacetate. Among these, propylene carbonate, γ-butyrolactone, triacetin, ethylene glycol diacetate, and triethylene glycol diacetate , dimethyl succinate, dimethyl glutarate, dimethyl adipate and the like are preferably used.

Also, the ester compound may be a branched ester compound. Examples of the branched ester compounds include dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, dimethyl 2-methyladipate, methyl 2-ethylhexanoate, ethyl 2-ethylhexanoate, dimethyl 2-methylsebacate, 2- Dimethyl ethylazelate, diethyl 2-ethylglutarate, dimethyl 2-(n-propyl)glutarate, diethyl 2-(n-butyl)succinate, dimethyl 2-(n-butyl)succinate, diethyl 2-methylpimelate , dimethyl 2-methylsuberate, and mixtures thereof. Among them, dimethyl 2-ethylsuccinate, dimethyl 2-methylglutarate, and dimethyl 2-methyladipate are preferable because the curing time of the water-soluble phenol resin can be adjusted within a more appropriate range.

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.

In the mixing step, from the viewpoint of suppressing deterioration of the working environment during casting, the amount of the binder composition for mold making is determined by the general formula (1) of the polymer in the composition for mold making. It is preferable to mix with the polymer in such a range that the amount of the represented monomer unit is 0.1 mol or more per 1 mol of various monomer units in the casting composition, and it is added so that the amount is 0.2 mol or more. From the viewpoint of suppressing a decrease in mold strength, it is preferably added in an amount of 50 mol or less, and more preferably in an amount of 40 mol or less. In addition, in the mixing step, the amount of the binder composition for mold making is adjusted from the viewpoint of suppressing the deterioration of the working environment during casting and from the viewpoint of suppressing the decrease in mold strength. It is preferable to mix with the polymer in such a range that the amount of the monomer unit represented by the general formula (1) in the polymer is 0.1 to 50 mol per 1 mol of various monomer units in the casting composition. , 0.2 to 40 mol.

The ratio of the refractory particles, the binder composition, and the curing agent in the mold manufacturing method can be set as appropriate. The binder composition is preferably 50 parts by mass or more, and more preferably 500 parts by mass or less. From the viewpoint of improving the final strength of the mold, the curing agent is preferably 10 parts by mass or more and more preferably 150 parts by mass or less with respect to 10000 parts by mass of the refractory particles.

[Curing process]
In the curing step, as a method for curing the mold composition, a known general technique can be used.

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

<Synthesis example>
[Water-soluble phenolic resin composition A]
7 mol of phenol, 50% by mass potassium hydroxide aqueous solution (0.40 times mol with respect to the total of phenol and 2,2′-biphenol), and 50% by mass sodium hydroxide aqueous solution (phenol and 2,2′-biphenol 0.40 times mol with respect to the total), water is added until the content of the resin (solid content) in the solution after the reaction is 50% by mass, and 2,2'-biphenol 3 mol of was added. After the temperature was raised to 80°C, 92% by mass paraformaldehyde (2.00 times mol per 10 mol of the total of phenol and 2,2'-biphenol) was added, and a polycondensation reaction was carried out at 80°C. Next, 0.5 parts by mass of γ-glycidoxypropyltrimethoxysilane was added to 100 parts by mass of the reaction solution to obtain a mol ratio of the monomer units derived from 2,2'-biphenol and the monomer units derived from phenol. Water-soluble phenolic resin containing water-soluble phenolic resin A (weight average molecular weight: 860) in a ratio (mol of monomer units derived from 2,2'-biphenol:mol of monomer units derived from phenol) of 3:7 A composition A was obtained.

[Water-soluble phenolic resin composition B]
Under the same conditions as the water-soluble phenolic resin composition A except that 3 mol of phenol and 7 mol of 2,2'-biphenol were used, the molar ratio of the derived monomer units (monomer unit derived from 2,2'-biphenol A water-soluble phenolic resin composition B containing a water-soluble phenolic resin B (weight-average molecular weight: 1085) in a ratio of 7:3 (mol of monomer units derived from phenol: mol of monomer units derived from phenol) was obtained.

[Biphenol resin composition C]
10 mol of 2,2′-biphenol, 50% by mass potassium hydroxide aqueous solution (0.40 times mol with respect to the total amount of 2,2′-biphenol), and 50% by mass aqueous sodium hydroxide solution (2,2′- 0.40 times mol with respect to the total amount of biphenol), water is added until the resin (solid content) content in the solution after the reaction is 50% by mass, and the temperature is raised to 80°C. 92% by mass of paraformaldehyde (2.00 times mol with respect to 10 mol of 2,2'-biphenol) was added, and a polycondensation reaction was carried out at 90°C. After the reaction, 0.5 part by mass of γ-glycidoxypropyltrimethoxysilane was added to 100 parts by mass of the reaction solution to obtain a biphenol resin composition C containing biphenol resin C (weight average molecular weight: 642). .

[Water-soluble phenolic resin composition D]
An aqueous solution obtained by mixing 10 mol of phenol, a 50% by mass aqueous potassium hydroxide solution (0.40 times mol with respect to phenol), and a 50% by mass aqueous sodium hydroxide solution (0.40 times mol with respect to phenol) was reacted. Water was added until the content of the resin (solid content) in the solution after completion was 50% by mass, 92% by mass paraformaldehyde (2.00 times mol relative to phenol) was added, and polymerization was performed at 80 ° C. A condensation reaction was carried out, and the reaction was continued until the weight average molecular weight of the water-soluble phenolic resin reached 2,000. Next, 0.5 part by mass of γ-glycidoxypropyltrimethoxysilane was added to 100 parts by mass of the reaction solution to obtain a water-soluble phenolic resin composition D containing a water-soluble phenolic resin D (weight average molecular weight: 2000). Obtained.

<Evaluation method>
[Weight average molecular weight of resin]
The weight average molecular weight was measured in terms of standard polyethylene by gel permeation chromatography.
[Measurement condition]
・Gel filtration chromatograph SC-8020 series manufactured by Tosoh Corporation ・Build-up system ・Column: G2000HXL + G4000HXL
・Detector: UV 285 nm
・Carrier: 1 mL/min of tetrahydrofuran ・Column temperature: 38°C

[Solid content mass of resin]
2 g of the resin composition and 1 g of water were added to a petri dish, mixed, and then heat-treated in an electric furnace heated to 105° C. for 4 hours. The mass g/2g×100 value after the heat treatment was taken as the solid content.

[Confirmation of resin structure]
It was confirmed by the following method that the water-soluble phenol resin composition A, the water-soluble phenol resin composition B, and the biphenol resin composition C each have a monomer unit represented by the general formula (1).

[Preparation of measurement sample]
For each of the water-soluble phenolic resin composition A, the water-soluble phenolic resin composition B, and the biphenolic resin composition C, using a gel dialysis membrane under the following conditions, fractional components (measurement sample) was obtained.
・ Apparatus: HLC-8320GPC (manufactured by Tosoh Corporation)
・ SEC separation column: (α (guard column), two α-M (analysis columns) in series)
・Calibration: Set using 6 types of standard polystyrene with different molecular weight orders from 5 million to 8 million weight average molecular weight

[Measurement of weight average molecular weight of resin]
The weight average molecular weight of the measurement sample for structure confirmation was analyzed by MALDI-TOF/MS under the following conditions.
・Device: ultrafle Xtreme (manufactured by Bruker Daltonics)
• Matrix: 2,5-dihydroxybenzoic acid was used as appropriate.
・Conditions: Reflector mode is Positive, measurement range Mw 0-3000, laser intensity 98%
・Detector: Linear mode, ion detection in positive mode

[Confirmation of the presence of the monomer unit represented by the general formula (1)]
From the difference between the weight average molecular weight of each measurement sample obtained by the measurement and each raw material monomer, the presence of the monomer unit represented by the general formula (1) in the polymer can be confirmed. It was a polymer in which the sum of m and n in (1) was 2.

[Sensory evaluation of odor]
Put 50.0 g of evaluation sand into a magnetic crucible of φ45×36, cover with a magnetic lid, put the crucible containing the evaluation sand in a small electric furnace KBF794N1 manufactured by Koyo Thermo Systems Co., Ltd. heated to 500 ° C., and display After the temperature reached 500°C, it was heated for 10 minutes. The crucible was removed from the electric furnace, and five panelists smelled the odor emanating from the gap between the crucible and the lid within 2 minutes. Evaluation criteria are shown below.
・Evaluation 1: Feels extremely strongly ・Evaluation 2: Feels very strongly ・Evaluation 3: Feels strongly ・Evaluation 4: Feels somewhat strongly ・Evaluation 5: Feels faintly

<Examples 1 to 5, and Comparative Examples 1 and 2>
To 100 parts by mass of refractory particles (silica sand manufactured by Yamakawa Sangyo Co., Ltd. (Fremantle new sand)), the formulation under the conditions shown in Table 1 was added and kneaded to obtain evaluation sand (sand composition for mold making). . The curing agent in Table 1 is triacetin.

<Mold Strength of Examples 1 to 5 and Comparative Examples 1 and 2>
In addition, it was confirmed that the mold strength of the test piece of φ50×50 mmH produced from new sand free mantle all had a compressive strength of 1.5 MPa or more, and could be used for mold making.

Claims (1)

A method for producing a polymer having a monomer unit represented by the following general formula (1) contained in a binder composition for mold making ,
A water-soluble phenol compound, 0.1 to 50 mol of an aromatic polyhydric alcohol represented by the following general formula (2) per 1 mol of the water-soluble phenol compound, and an aldehyde compound are reacted under alkaline conditions to obtain the above A production method comprising a step of obtaining a polymer.

(In general formula (1), m and n each indicate the number of hydroxyl groups bonded to a phenyl group and are 1.)

(In general formula (2), m and n each indicate the number of hydroxyl groups bonded to a phenyl group and are 1.)