JP5563875B2 - Kit for producing a mold composition - Google Patents

Description

  The present invention relates to a kit for producing a mold composition used together with refractory particles, a mold composition using the same, and a mold production method.

  The acid-curable self-hardening mold is obtained by adding a mold-forming binder containing an acid-curable resin and a curing agent containing an organic sulfonic acid, sulfuric acid, phosphoric acid, etc. to refractory particles such as silica sand, After kneading these, the obtained kneaded sand is filled in a prototype such as a wooden mold, and the acid curable resin is cured to produce. Furan resin, phenol resin, etc. are used for acid curable resin. Furan resin is furfuryl alcohol, furfuryl alcohol / urea formaldehyde resin, furfuryl alcohol / formaldehyde resin, furfuryl alcohol / phenol / formaldehyde. Resins and other known modified furan resins are used. The obtained mold is used when casting a casting such as a machine casting part, a construction machine part, or an automobile part.

  An improvement of the final strength of the mold is an important item in making the above-described mold or casting a desired casting using the mold. The final strength of the mold is particularly necessary when producing large molds. If the strength is insufficient, the mold may crack or core cracks may occur during casting, causing danger to the operator. There is a risk that the resulting casting will be defective.

  Another important item is the characteristics of the curing agent used for curing the furan resin, particularly storage stability and handling properties. As the curing agent, an aqueous xylene sulfonic acid solution is generally used. However, in a low temperature environment, the xylene sulfonic acid may be crystallized to reduce storage stability. In addition, the xylene sulfonic acid aqueous solution has a high viscosity in a low temperature environment, and thus there is a possibility that the handling property is lowered. Therefore, usually, storage stability and handling properties are ensured by adding sulfuric acid to the xylene sulfonic acid aqueous solution. However, when the sulfuric acid content in the curing agent is increased, there is a problem that the final strength of the mold is lowered.

  Patent Document 1 proposes a binder composition for mold making containing an acid curable resin and a metal chloride in order to improve the initial strength of the mold.

JP 2010-29905 A

  However, the inventors have found that it is difficult to improve the final strength of the mold with the binder of Patent Document 1. Patent Document 1 does not mention the production of a mold in a low temperature environment, nor does it mention the storage stability and handling properties of the curing agent.

  The present invention can ensure the storage stability and handling properties of the curing agent and improve the final strength of the mold, and a kit for producing a mold composition, and a mold composition using the kit, and A method for producing a mold is provided.

  A kit for producing a mold composition of the present invention is a kit for producing a mold composition used together with refractory particles, comprising a binder containing a furan resin and a curing agent. And the binder contains 0.5 to 5.0% by weight of calcium chloride, and the curing agent contains 20 to 60% by weight of sulfuric acid and 0 to 60% by weight of the organic sulfonic acid compound. In the curing agent, the weight ratio of sulfuric acid to the total weight of sulfuric acid and the organic sulfonic acid compound {sulfuric acid / (sulfuric acid + organic sulfonic acid compound)} is 0.35 to 1.00.

  The composition for casting_mold | template of this invention is a composition for casting_mold | templates formed by mixing a refractory particle, the said binder and the said hardening | curing agent which comprise the kit of this invention.

  The mold production method of the present invention is a mold production method in which the mold composition of the present invention is filled in a mold for mold production and the mold composition is cured.

  According to the kit for producing the mold composition of the present invention, the storage stability and handling properties of the curing agent can be secured, and the final strength of the mold can be improved. In addition, according to the mold composition and the mold manufacturing method of the present invention, it is possible to ensure the handleability of the mold composition when filling the mold for mold production, and to improve the final strength of the mold. .

  The kit for producing the mold composition of the present invention (hereinafter also simply referred to as “kit”) is a kit used together with refractory particles, and comprises a binder containing a furan resin and a curing agent. This is a two-part kit. Hereinafter, the components contained in the binder and the curing agent of the kit of the present invention will be described.

[Binder]
<Furan resin>
As the furan resin contained in the binder, known resins can be used, for example, furfuryl alcohol, condensates of furfuryl alcohol and aldehydes, condensates of furfuryl alcohol and urea, furfuryl alcohol and phenols. Selected from the group consisting of a condensate of aldehydes with furfuryl alcohol, melamine and aldehydes, and a condensate of furfuryl alcohol with urea and aldehydes, or selected from these groups What consists of 2 or more types of mixtures can be used. Moreover, the cocondensate which consists of 2 or more types chosen from these groups can also be used. Since furfuryl alcohol can be produced from a plant which is a non-petroleum resource, it is preferable to use the enumerated furan resins from the viewpoint of the global environment. From the viewpoint of cost and mold strength, it is preferable to use furfuryl alcohol, a condensate of furfuryl alcohol and aldehydes, and a condensate of furfuryl alcohol, urea and aldehydes. It is more preferable to use a condensate of furyl alcohol, urea and aldehydes. It is more preferable to use formaldehyde as the aldehydes.

  Examples of the aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, glyoxal, furfural, terephthalaldehyde, and the like, and one or more of these can be used as appropriate. From the viewpoint of improving the 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 or terephthalaldehyde.

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

  Specific examples of furan resins include commercially available products such as Kaolitener EF-5501 (a furan resin in which a silane coupling agent is added to a furfuryl alcohol solution of a condensate of furfuryl alcohol, urea and formaldehyde) manufactured by Kao Quaker. It is done.

  The content of the furan resin in the binder is preferably 55 to 99.5% by weight, more preferably 60 to 90% by weight, and still more preferably 65 to 85% from the viewpoint of sufficiently expressing the mold strength. % By weight.

<Calcium chloride>
The binder used in the present invention contains calcium chloride in order to improve the final strength of the mold. Although it does not specifically limit as calcium chloride, For example, commercial items, such as a calcium chloride dihydrate (the reagent and special grade by Wako Pure Chemical Industries, Ltd.), can be used.

  The method for adding calcium chloride is not particularly limited, and may be added at the time of synthesizing the furan resin, or may be added after the synthesis of the furan resin. In the furan resin synthesis step, when the condensation reaction is performed in the presence of calcium chloride, conventionally known methods can be employed for the other condensation reaction conditions.

  The content of calcium chloride in the binder is 0.5 to 5.0% by weight from the viewpoint of solubility in furan resin and improvement of the final strength of the mold, and is 1.0 to 5.0. % By weight is preferable, and 2.0 to 4.0% by weight is more preferable.

<Curing accelerator>
The binder used in the present invention (or the mold composition of the present invention) may contain a curing accelerator from the viewpoint of improving the mold strength. As the curing accelerator, from the viewpoint of improving the mold strength, from a compound represented by the following general formula (1) (hereinafter referred to as curing accelerator (1)), a phenol derivative, an aromatic dialdehyde, and a tannin compound. One or more selected from the group consisting of In addition, a hardening accelerator may be contained as one component of furan resin.

〔式中、Ｘ₁及びＸ₂は、それぞれ水素原子、ＣＨ₃又はＣ₂Ｈ₅の何れかを表す。〕

[Wherein, X ₁ and X ₂ each represent a hydrogen atom, CH ₃ or C ₂ H ₅ . ]

  As the curing accelerator (1), 2,5-bishydroxymethylfuran, 2,5-bismethoxymethylfuran, 2,5-bisethoxymethylfuran, 2-hydroxymethyl-5-methoxymethylfuran, 2-hydroxy Examples include methyl-5-ethoxymethylfuran and 2-methoxymethyl-5-ethoxymethylfuran. Among these, 2,5-bishydroxymethylfuran is preferably used from the viewpoint of improving the mold strength. The content of the curing accelerator (1) in the binder is 0.5 to 63% by weight from the viewpoint of the solubility of the curing accelerator (1) in the furan resin and the mold strength. Is preferably 1.8 to 50% by weight, more preferably 2.5 to 50% by weight, and still more preferably 3.0 to 40% by weight.

  Examples of the phenol derivative include resorcin, cresol, hydroquinone, phloroglucinol, methylene bisphenol, and the like. Of these, resorcin and phloroglucinol are preferred from the viewpoint of improving the mold strength. The content of the phenol derivative in the binder is preferably 1.5 to 25% by weight from the viewpoint of the solubility of the phenol derivative in the furan resin and the mold strength, and is preferably 2.0 to It is more preferably 15% by weight, and further preferably 3.0 to 10% by weight.

  Examples of the aromatic dialdehyde include terephthalaldehyde, phthalaldehyde, isophthalaldehyde, and derivatives thereof. These derivatives mean compounds having a substituent such as an alkyl group on the aromatic ring of an aromatic compound having two formyl groups as the basic skeleton. From the viewpoint of improving the mold strength, terephthalaldehyde and terephthalaldehyde derivatives are preferable, and terephthalaldehyde is more preferable. The content of the aromatic dialdehyde in the binder is preferably from the viewpoint of sufficiently dissolving the aromatic dialdehyde in the furan resin, from the viewpoint of improving the mold strength, and from the viewpoint of suppressing the odor of the aromatic dialdehyde itself. Is 0.1 to 15% by weight, more preferably 0.5 to 10% by weight, still more preferably 1 to 5% by weight.

  The tannin compound is preferably condensed tannin or hydrolyzed tannin from the viewpoint of improving the template strength, and more preferably an extract from a plant from the viewpoint of the global environment. In particular, condensed tannins extracted from bark and hydrolyzed tannins extracted from plant insects are preferred.

<Moisture>
The binder used in the present invention may further contain moisture. For example, when synthesizing various condensates such as a condensate of furfuryl alcohol and aldehydes, an aqueous raw material is used or condensed water is generated. However, when such a condensate is used as a binder, it is not necessary to remove these waters derived from the synthesis process. Further, moisture may be further added for the purpose of adjusting the binder to a viscosity that is easy to handle. However, if the moisture becomes excessive, the curing reaction of the furan resin may be inhibited. Therefore, the moisture content in the binder is preferably in the range of 0.5 to 30% by weight. From the viewpoint of facilitating handling and maintaining the curing reaction rate, the range of 1 to 10% by weight is more preferable, and the range of 3 to 7% by weight is even more preferable. Further, from the viewpoint of improving the mold strength, it is preferably 10% by weight or less, more preferably 7% by weight or less, and still more preferably 4% by weight or less.

<Other additives>
The binder used in the present invention may further contain an additive such as a silane coupling agent. For example, it is preferable that a silane coupling agent is contained because the strength of the obtained mold can be improved. As the silane coupling agent, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl)- aminosilanes such as γ-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-β- (aminoethyl) -α-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycol Epoxy silanes such as sidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, ureidosilane, mercaptosilane, sulfide silane, methacryloxysilane, acryloxysilane, etc. Used. Amino silane, epoxy silane, and ureido silane are preferable. The content of the silane coupling agent in the binder is preferably 0.01 to 0.5% by weight, more preferably 0.05 to 0.3% by weight from the viewpoint of mold strength. . Note that the silane coupling agent may be contained as one component of a furan resin.

[Curing agent]
The curing agent used in the present invention is a curing agent that cures the binder, and the storage stability and handling properties of the curing agent, particularly the storage stability of the curing agent in a low temperature environment (for example, 10 ° C. or less) and In order to improve handling properties and improve the final strength of the mold, sulfuric acid and an organic sulfonic acid compound are contained in a specific ratio.

<Sulfuric acid>
The sulfuric acid used in the present invention is a substance represented by the chemical formula of H ₂ SO ₄ , and is generally available as a 96 to 98% by weight sulfuric acid aqueous solution as a commercial product.

  The content of sulfuric acid in the curing agent is 20% by weight or more, preferably 25% by weight or more, and preferably 30% by weight or more from the viewpoint of improving the storage stability and handling properties of the curing agent. More preferred. Further, from the viewpoint of improving the final strength of the mold, it is 60% by weight or less, preferably 55% by weight or less, and more preferably 50% by weight or less. Taking the above viewpoints together, the content of sulfuric acid in the curing agent is 20 to 60% by weight, preferably 25 to 55% by weight, and more preferably 30 to 50% by weight.

<Organic sulfonic acid compound>
Examples of the organic sulfonic acid compounds include alkylbenzene sulfonic acids such as methane sulfonic acid, ethane sulfonic acid, and ethyl benzene sulfonic acid, alkanes such as benzene sulfonic acid, toluene sulfonic acid, and xylene sulfonic acid, aryl sulfonic acids, and phenol sulfonic acid. However, from the viewpoint of improving the final strength of the template and from the viewpoint of cost, one or more selected from the group consisting of xylene sulfonic acid, toluene sulfonic acid, ethylbenzene sulfonic acid, and methane sulfonic acid are preferable, xylene sulfonic acid, One or more selected from the group consisting of toluenesulfonic acid and methanesulfonic acid is more preferable.

  The organic sulfonic acid-based compound may contain an isomer generated during production. For example, taking xylene sulfonic acid as an example, m-xylene-4-sulfonic acid, m-xylene-2-sulfonic acid, o-xylene-4-sulfonic acid, o-xylene-2-sulfonic acid, p-xylene 2-sulfonic acid and disulfonic acid such as m-xylene-2,4-disulfonic acid and m-xylene-2,6-disulfonic acid may be contained as impurities. These types of sulfonic acids can be identified by NMR analysis.

  The content of the organic sulfonic acid compound in the curing agent is 0% by weight or more, preferably 10% by weight or more, and more preferably 20% by weight or more from the viewpoint of improving the final strength of the mold. preferable. Further, from the viewpoint of improving the storage stability and handling properties of the curing agent, it is 60% by weight or less, preferably 50% by weight or less, and more preferably 30% by weight or less. In summary of the above viewpoints, the content of the organic sulfonic acid compound in the curing agent is 0 to 60% by weight, preferably 10 to 50% by weight, and more preferably 20 to 30% by weight. preferable.

  In the curing agent used in the present invention, the storage stability and handling properties of the curing agent, particularly the storage stability and handling properties of the curing agent in a low temperature environment (for example, 10 ° C. or less) are improved, and the final strength of the mold is increased. From the viewpoint of improvement, the weight ratio {sulfuric acid / (sulfuric acid + organic sulfonic acid compound)} of sulfuric acid to the total weight of sulfuric acid and the organic sulfonic acid compound is 0.35 to 1.00, and 0.50 to 0 .90 is preferable, and 0.60 to 0.85 is more preferable.

<Other ingredients>
The curing agent used in the present invention may contain known acidic substances as components other than sulfuric acid and organic sulfonic acid compounds. Examples of the acidic substance include one or a mixture of two or more organic acids such as carboxylic acids, phosphoric acid compounds such as phosphoric acid, and inorganic acids such as nitric acid. The content of the acidic substance in the curing agent is preferably 0.1 to 30% by weight and more preferably 0.1 to 20% by weight from the viewpoint of improving the mold strength.

  Furthermore, the curing agent can contain one or more solvents selected from the group consisting of alcohols, ether alcohols and esters, and carboxylic acids. Among these, alcohols and ether alcohols are preferable and ether alcohols are more preferable from the viewpoint of improving the mold strength. Moreover, when the said solvent and carboxylic acid are contained, since the moisture content in a hardening | curing agent is reduced, mold intensity | strength further improves. The content of the solvent or the carboxylic acid in the curing agent is preferably 5 to 50% by weight and more preferably 10 to 40% by weight from the viewpoint of improving the mold strength. Moreover, it is preferable to contain methanol and ethanol from a viewpoint of reducing the viscosity of a hardening | curing agent.

  From the viewpoint of improving the mold strength, the alcohols are preferably propanol, butanol, pentanol, hexanol, heptanol, octanol, benzyl alcohol, and the ether alcohols include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, Ethylene glycol monohexyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, ethylene glycol monophenyl ether are preferred, and esters include butyl acetate, butyl benzoate, ethylene glycol monobutyl ether acetate , Diethylene glycol monobutyl ether acetate Over door is preferable. As the carboxylic acids, a carboxylic acid having a hydroxyl group is preferable, and lactic acid, citric acid, and malic acid are more preferable from the viewpoint of improving the template strength and reducing the odor. In addition, the curing agent can use water such as ion-exchanged water as the balance other than the above components, but from the viewpoint of improving the storage stability and handling properties of the curing agent, the water content in the curing agent is: It is preferably 10 to 50% by weight, more preferably 15 to 50% by weight, and still more preferably 20 to 50% by weight.

  The composition for casting_mold | template of this invention is a composition for casting_mold | templates formed by mixing a refractory particle, the said binder and the said hardening | curing agent which comprise the kit of this invention. 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. Processed ones can also be used.

  The ratio of the refractory particles, the binder and the curing agent in the mold composition of the present invention can be appropriately set, but the binder is 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the refractory particles. And the range of 0.07-1 weight part of hardening | curing agents is preferable. With such a ratio, it is easy to obtain a mold having sufficient strength. Furthermore, the content of the curing agent is 10 to 40 parts by weight with respect to 100 parts by weight of the furan resin in the binder from the viewpoint of minimizing the amount of water contained in the mold and the mixing efficiency in the mixer. Preferably, it is 15 to 35 parts by weight, more preferably 18 to 25 parts by weight.

  The mold production method of the present invention is a mold production method in which the mold composition (casting sand) of the present invention is filled in a mold for mold production and the mold composition is cured. In the mold manufacturing method of the present invention, a mold can be manufactured using the process of the conventional mold manufacturing method. For example, a mold composition (casting sand) is prepared by adding the binder and the curing agent to the refractory particles and kneading them with a batch mixer or a continuous mixer. A mold can be obtained by filling the mold for use and curing the mold composition.

  In the conventional mold manufacturing method, the handling property of the mold composition may be lowered due to an increase in the viscosity of the curing agent in the mold composition in a low temperature environment. However, in the method for producing a mold of the present invention, by using a curing agent containing sulfuric acid and an organic sulfonic acid compound in a specific ratio, it is preferably 10 ° C. or less, more preferably 5 ° C. or less in a low temperature environment. The handleability of the mold composition can be ensured even at ambient temperature. In addition, in the manufacturing method of the casting_mold | template of this invention, it is preferable to add the said binder after adding the said hardening | curing agent to a refractory particle from a viewpoint of ensuring pot life.

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

<Furan resin used in binder>
As the furan resin, a furan resin obtained by adding a silane coupling agent to a furfuryl alcohol solution of a condensate of furfuryl alcohol, urea and formaldehyde (Kao Quaker, Caolitener EF-5501, nitrogen content: 1.8) Wt%, water content: 3.4 wt%, viscosity: 17 mPa · s / 25 ° C.). The content of free furfuryl alcohol in the furan resin was 72% by weight, and the content of the silane coupling agent (N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane) was 0.00. It was 1% by weight. The measuring method of the said nitrogen content, water content, and viscosity is shown below.

<Nitrogen content in furan resin>
The nitrogen content in the furan resin was measured based on the Kjeldahl method shown in JIS K 0102.

<Water content in furan resin>
The water content in the furan resin was measured based on the Karl Fischer method shown in JIS K 2275.

<Viscosity of furan resin>
The viscosity of the furan resin was measured with an E-type viscometer based on JIS Z 8803.

<Preparation of the composition for casting_mold | template of Examples 1-9 and Comparative Examples 1-8>
Under conditions of 5 ° C. and 55% relative humidity, 10.0 g of the curing agent shown in Table 1 is added to 2 kg of silica sand (manufactured by Yamakawa Sangyo Co., Ltd., fresh mantle new sand), kneaded, and then the amount shown in Table 1 Then, 20.0 g of a binder obtained by mixing EF-5501, which is the furan resin, and calcium chloride dihydrate (a reagent / special grade manufactured by Wako Pure Chemical Industries, Ltd.) was added, and these were mixed. A mold composition (casting sand) was obtained.

  The following evaluation was performed about the used hardening | curing agent and the obtained composition for casting_mold | templates. The results are shown in Table 1.

<Storage stability of curing agent>
Each 30 g of the curing agent shown in Table 1 was weighed into a glass screw tube with a capacity of 50 mL, sealed, and stored at −20 ° C. for 3 days using a low-temperature thermostat (manufactured by ESPEC, LU-113). Evaluation was performed according to the following criteria.
A: It remained liquid.
B: Although not solidified at the time of preparation (5 ° C.), it solidified during storage.
C: Solidified at the time of preparation (5 ° C.).

<Handling property of curing agent>
The handling property of the curing agent was evaluated according to the following criteria by measuring the viscosity of the curing agent (25 ° C.) with a B-type viscometer based on JIS Z 8803.
A: The viscosity is 30 mPa · s or less.
B: The viscosity is more than 30 mPa · s and less than 50 mPa · s.
C: Viscosity is 50 mPa · s or more or already solidified.

<Mold strength measurement>
The mold composition immediately after kneading was filled into a cylindrical test piece frame having a diameter of 50 mm and a height of 50 mm. Samples left for 0.5 hours and 1 hour under conditions of 5 ° C. and 55% relative humidity were subjected to die cutting, and the compressive strength was measured by the method described in JIS Z 2604-1976, respectively, and the measured values obtained Were the mold strengths after 0.5 hour and 1 hour, respectively. Separately, the mold composition immediately after kneading is filled into a cylindrical test piece frame having a diameter of 50 mm and a height of 50 mm, left standing at 5 ° C. and a relative humidity of 55% for 3 hours, and then removed from the mold. Compressive strength was measured by the method described in JIS Z 2604-1976 for a sample that had been left for 21 hours under the conditions of ℃ and relative humidity of 55% (total time left for 24 hours). The mold strength after 24 hours was used.

  As shown in Table 1, the curing agents of the examples all had good storage stability and handling properties. Moreover, since all the molds obtained in the examples have high mold strength after 24 hours, it was confirmed that the final strength of the mold can be improved according to the present invention. On the other hand, the comparative example was a result in which at least one evaluation item was significantly inferior to the example.

Claims (5)

A kit for producing a mold composition for use with refractory particles comprising:
It consists of a binder containing a furan resin and a curing agent,
The binder contains 0.5 to 5.0% by weight of calcium chloride;
The curing agent contains 20 to 60% by weight of sulfuric acid and 0 to 60% by weight of an organic sulfonic acid compound,
In the curing agent, the weight ratio of sulfuric acid to the total weight of sulfuric acid and the organic sulfonic acid compound {sulfuric acid / (sulfuric acid + organic sulfonic acid compound)} is 0.35 to 1.00.   The furan resin comprises furfuryl alcohol, furfuryl alcohol and aldehyde condensate, furfuryl alcohol and urea condensate, furfuryl alcohol, phenol and aldehyde condensate, furfuryl alcohol, melamine and aldehyde. The kit according to claim 1, comprising a condensate and one or more selected from the group consisting of a condensate of furfuryl alcohol, urea, and aldehydes, or a cocondensate consisting of two or more selected from the above group.   The composition for casting_mold | templates formed by mixing a refractory particle, the said binder and the said hardening | curing agent which comprise the kit of Claim 1 or 2.   A method for producing a mold, wherein the mold composition according to claim 3 is filled in a mold for producing a mold, and the mold composition is cured.   The method for producing a mold according to claim 4, wherein the mold composition is filled with the mold composition at an atmospheric temperature of 10 ° C. or less.