Two-component furan resin binder for molding and method for preparing molding sand for casting

Abstract

The application discloses a two-component furan resin binder for molding and a preparation method of foundry molding sand, wherein the binder comprises furan resin and hydrocarbon alkyl alkoxysilane; the hydrocarbon alkyl alkoxysilane comprises a compound with a structure shown in the following formula (I) and / or formula (II), the formula (I) is (OR 1 ) m1 (R 2 ) 4‑m1 Si, the formula (II) is (OR 3 ) n1 (R 4 ) 3‑ n1 Si-R 5 ‑Si(R 6 ) 3‑n2 (OR 7 ) n2 ; wherein R 1 , R 3 and R 7 are each independently selected from alkyl with 1-20 carbon atoms, R 2 , R 4 and R 6 are each independently selected from alkyl with 1-20 carbon atoms and alkenyl with 2-20 carbon atoms, R 5 is selected from alkylene with 1-20 carbon atoms and alkenylene with 2-20 carbon atoms, m1 is 1, 2, 3 or 4, and n1 and n2 are each independently 1, 2 or 3. The binder has excellent curing performance, excellent deep curing performance, and can accelerate the curing speed and reduce the emission of harmful substances. The molding sand prepared by using the binder has high tensile strength and excellent heat resistance and moisture resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of foundry binders, in particular to a two-component furan resin binder for molding, a two-component furan resin binder kit and a method for preparing foundry molding sand. BACKGROUND

[0002] Furan resin is usually cured by using p-toluenesulfonic acid, xylene sulfonic acid, methyl sulfate and the like as a curing agent. In the process of molding sand casting, furan resin as a binder can make the molding sand have high strength and excellent collapsibility at room temperature and high temperature, but the use of furan resin also causes the release of formaldehyde during molding and the emission of harmful gases such as nitrogen oxides, sulfur oxides, carbon oxides and the like during casting, which has high odor and large amount of emission. In addition, when preparing large castings, furan resin has the disadvantages of poor deep hardening ability and low production efficiency.

[0003] At present, the inorganic binders for foundry molding mainly include carbon dioxide hardened water glass, organic ester hardened modified water glass and inorganic warm core box, etc. The inorganic binder has the advantages of no odor and less VOCs emission during molding and casting, but has the disadvantages of low sand strength and high resin addition amount. In addition, since the inorganic binder contains a large amount of alkali metal salt, its regeneration performance and moisture resistance are poor, and a large amount of waste sand is often produced when using the inorganic binder. Although great progress has been made in the regeneration of inorganic binder sand in recent years, such as hot dry regeneration, wet regeneration and dry-wet mixed regeneration using reagents, the regeneration performance of inorganic binder sand is still far from that of organic binder sand; in addition, the moisture resistance of inorganic binder is poor, and the molding sand using inorganic binder is not suitable for storage, or must be stored in a constant temperature and humidity environment.

[0004] The curing performance of the binder affects the tensile strength, heat resistance, moisture resistance, stability and defect resistance of the sand mold / sand core. The deep curing performance of the binder is also an important indicator for evaluating the quality of the binder and the process applicability, which refers to the ability of the binder to achieve uniform and sufficient curing inside the sand mold or sand core, especially in the thick section or complex structure area, which directly affects the tensile strength, heat resistance, moisture resistance, stability and defect resistance of the sand mold / sand core. However, the curing performance of the binder in the prior art, especially the deep curing performance, is poor. SUMMARY

[0005] In order to overcome the drawbacks of the binder in the prior art, the present application provides a two-component furan resin binder for molding, which has excellent overall curing performance, especially excellent deep curing performance, and can significantly improve the casting efficiency. At the same time, the two-component furan resin binder of the present application can also reduce the emission of harmful gases during the curing process.

[0006] Specifically, the technical solutions of the present application are as follows:

[0007] 1. A two-component furan resin binder for molding, comprising: a furan resin and a hydrocarbylalkoxysilane.

[0008] The hydrocarbylalkoxysilane comprises a compound having a structure represented by the following formula (I) and / or formula (II):

[0009] (OR 1 ) m1 (R 2 ) 4-m1 Si Formula (I),

[0010] (OR 3 ) n1 (R 4 ) 3-n1 Si-R 5 -Si(R 6 ) 3-n2 (OR 7 ) n2 Formula (II);

[0011] wherein R 1 , R 3 and R 7 are each independently selected from an alkyl group having 1 to 20 carbon atoms, R 2 , R 4 and R 6 are each independently selected from an alkyl group having 1 to 20 carbon atoms and an alkenyl group having 2 to 20 carbon atoms, R 5 is selected from an alkylene group having 1 to 20 carbon atoms and an alkenylene group having 2 to 20 carbon atoms, m1 is 1, 2, 3 or 4, and n1 and n2 are each independently 1, 2 or 3.

[0012] 2. The two-component furan resin binder for molding according to item 1, wherein the mass ratio of the furan resin and the hydrocarbylalkoxysilane is (1 to 99): 1, preferably (5 to 50): 1.

[0013] 3. The two-component furan resin binder for molding according to item 1 or 2, wherein R 1 , R 3 and R 7 are each independently selected from an alkyl group having 1 to 10, preferably 1 to 4, more preferably 1 to 2, carbon atoms.

[0014] Preferably, R 2 , R 4 and R 6 are each independently selected from an alkyl group having 1 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms; more preferably, R2 R 4 and R 6 are each independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and alkenyl groups having 2 to 4 carbon atoms; further preferably, R 2 R 4 and R 6 are each independently a methyl group or an ethyl group;

[0015] Preferably, R 5 is selected from the group consisting of alkylene groups having 1 to 10 carbon atoms and alkenylene groups having 2 to 10 carbon atoms; more preferably, R 5 is selected from the group consisting of alkylene groups having 1 to 4 carbon atoms and alkenylene groups having 2 to 4 carbon atoms; further preferably, R 5 is a methylene group or an ethylene group.

[0016] 4. The two-component furan resin binder for molding according to item 1 or 2, wherein m1 is 2, 3 or 4, preferably 3.

[0017] Preferably, n1 and n2 are each independently 2 or 3.

[0018] 5. The two-component furan resin binder for molding according to item 1 or 2, wherein the content of silicon in the hydrocarbylalkoxysilane is 2 to 30 wt%.

[0019] 6. The two-component furan resin binder for molding according to item 1 or 2, wherein the hydrocarbylalkoxysilane is one or two or more selected from the group consisting of trimethoxymethylsilane, triethoxymethylsilane, methoxytrimethylsilane, dimethoxydimethylsilane, trimethoxyethylsilane, 1,2-bistrimethoxysilylethane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxyethylsilane, tetraethoxysilane, tetramethoxysilane, 1,2-bistrimethoxysilylethane, vinyltrimethoxysilane and vinyltriethoxysilane.

[0020] Preferably, the hydrocarbylalkoxysilane is one or two or more selected from the group consisting of trimethoxymethylsilane, trimethoxyethylsilane, 1,2-bistrimethoxysilylethane, triethoxymethylsilane, triethoxyethylsilane and 1,2-bistrimethoxysilylethane.

[0021] More preferably, the hydrocarbylalkoxysilane comprises 1,2-bistrimethoxysilylethane.

[0022] 7. The two-component furan resin binder for molding according to item 1 or 2, wherein the furan resin is one or two or more selected from the group consisting of furfuryl alcohol formaldehyde resin, urea formaldehyde-modified furan resin, phenol formaldehyde-modified furan resin, phenol urea formaldehyde-modified furan resin, furfural resin, furfuryl ketone resin.

[0023] 8. The two-component furan resin binder for molding according to item 1 or 2, wherein the furan resin and the hydrocarbylalkoxysilane are stored separately or mixed.

[0024] 9. Use of a furan resin and / or a hydrocarbylalkoxysilane for the production of a two-component furan resin binder for molding.

[0025] wherein the furan resin and the hydrocarbylalkoxysilane are as defined in any one of items 1 to 8.

[0026] 10. A two-component furan resin binder kit comprising an A-agent and a B-agent, the A-agent comprising a furan resin as defined in any one of items 1 to 8 and the B-agent comprising a hydrocarbylalkoxysilane as defined in any one of items 1 to 8.

[0027] 11. A method for producing a molding sand for casting, wherein the method comprises the steps of:

[0028] adding a two-component furan resin binder for molding comprising a furan resin and a hydrocarbylalkoxysilane and a curing agent to refractory aggregates to obtain a mixture, and placing the mixture into a mold to obtain a molding sand for casting.

[0029] wherein the two-component furan resin binder for molding is as defined in any one of items 1 to 8.

[0030] 12. The method for producing according to item 11, wherein the two-component furan resin binder for molding is present in an amount of 0.5 wt% to 3 wt%, preferably 0.7 wt% to 1.5 wt%, relative to the refractory aggregates.

[0031] Effects of the invention

[0032] (1) The two-component furan resin binder for molding of the present application comprises a furan resin and a hydrocarbylalkoxysilane. Compared to a common furan resin binder for molding (furan resin), the use of the binder of the present application allows for a reduction of the amount of furan resin to be added, which can be up to 30%, and achieves a better effect than the common furan resin binder for molding, i.e. a lower emission of nitrogen oxides, sulfur oxides, carbon oxides, etc. and a better curing performance. In the case of the same amount of curing agent and the same amount of binder, the binder of the present application allows for a significantly faster curing speed. Based on this effect, the use of the binder of the present application in the process of producing a molding sand also allows for a reduction of the amount of curing agent to be added, while ensuring the strength and heat resistance of the molding sand, and further reducing the emission of nitrogen oxides, sulfur oxides, carbon oxides, etc. during casting.

[0033] (2) The binder of the present application does not contain an alkali metal salt, and thus the sand regeneration performance and the moisture resistance can be improved to a level comparable to or even better than that of sand using a general furan resin binder.

[0034] (3) Since the furan resin and the curing agent undergo a polycondensation reaction to generate water, and the hydrocarbylalkoxysilane of the present application undergoes a hydrolysis reaction with the water, the molding sand obtained has less moisture, and thus the curing performance of the binder of the present application is more excellent than that of a general furan resin binder, and the deep curing performance is more excellent, and the binder of the present application can significantly improve the casting efficiency.

[0035] (4) The molding sand prepared using the binder of the present application has high tensile strength, excellent heat resistance, and excellent moisture resistance. DETAILED DESCRIPTION

[0036] Hereinafter, the present application will be described in detail. It is to be noted that the term "comprising" or "including" as used in the specification and claims means "including but not limited to," as the term is used in the art of describing general principles of the present application. The description that follows is intended to be a best mode of practicing the present application, but is not intended to limit the scope of the present application. The scope of the present application is defined by the appended claims.

[0037] In one aspect, the present application provides a two-component furan resin binder for molding, wherein the two-component furan resin binder for molding comprises: a furan resin and a hydrocarbylalkoxysilane.

[0038] The hydrocarbylalkoxysilane comprises a compound having a structure represented by the following Formula (I) and / or Formula (II):

[0039] (OR 1 ) m1 (R 2 ) 4-m1 Si Formula (I),

[0040] (OR 3 ) n1 (R 4 ) 3-n1 Si-R 5 -Si(R 6 ) 3-n2 (OR 7 ) n2 Formula (II);

[0041] wherein R 1 , R 3 , and R 7 are each independently selected from an alkyl group having 1 to 20 carbon atoms, R 2 , R4 and R 6 each independently selected from the group consisting of an alkyl group having 1 to 20 carbon atoms and an alkenyl group having 2 to 20 carbon atoms, R 5 selected from the group consisting of an alkylene group having 1 to 20 carbon atoms and an alkenylene group having 2 to 20 carbon atoms, m1 is 1, 2, 3, or 4, and n1 and n2 are each independently 1, 2, or 3.

[0042] The two-component molding furan resin binder of the present application comprises a furan resin and a hydrocarbylalkoxysilane. Compared with a common two-component molding furan resin binder, the amount of furan resin used in the binder of the present application can be reduced by up to 30%, and the binder of the present application can achieve better effects than the common two-component molding furan resin binder, such as lower emissions of nitrogen oxides, sulfur oxides, carbon oxides, and the like, and better curing performance. In addition, the hydrocarbylalkoxysilane of the present application can hydrolyze with water, so that the prepared molding sand has less water content. Therefore, compared with the common furan resin binder, the curing performance of the binder of the present application is better, and the deep curing performance is more excellent. The binder of the present application can significantly improve the casting efficiency. At the same time, the molding sand prepared using the binder of the present application has high tensile strength, excellent heat resistance, and excellent moisture resistance.

[0043] In some embodiments, the two-component molding furan resin binder of the present application consists of a furan resin and a hydrocarbylalkoxysilane.

[0044] In the present application, the alkyl group having 1 to 20 carbon atoms may, for example, be a substituted or unsubstituted, straight-chain or branched alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, a neopentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, an eicosyl group, and the like. Preferably, the alkyl group has 1 to 10 carbon atoms, more preferably 1 to 4 carbon atoms, and most preferably a methyl group or an ethyl group.

[0045] In the present application, the alkenyl group having 2 to 20 carbon atoms may, for example, be a substituted or unsubstituted, straight-chain or branched alkenyl group, and examples thereof include a vinyl group, a propenyl group, an isopropenyl group, a butenyl group, an isobutenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a nonenyl group, a decenyl group, an undecenyl group, a dodecenyl group, a tridecenyl group, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group, a heptadecenyl group, an octadecenyl group, a nonadecenyl group, an eicosenyl group, and the like. Preferably, the alkenyl group has 2 to 10 carbon atoms, more preferably 2 to 4 carbon atoms, and most preferably a vinyl group.

[0046] In the present application, the alkylene group having 1 to 20 carbon atoms can be a substituted or unsubstituted, straight-chain or branched alkylene group, and examples thereof include a methylene group, an ethylene group, a propylene group, an isopropylene group, a butylene group, a sec-butylene group, an isobutylene group, a t-butylene group, a pentylene group, a neopentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, an undecylene group, a dodecylene group, a tridecylene group, a tetradecylene group, a pentadecylene group, a hexadecylene group, a heptadecylene group, an octadecylene group, a nonadecylene group, an icosylene group, and the like, preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and most preferably a methylene group or an ethylene group.

[0047] In the present application, the alkenylene group having 2 to 20 carbon atoms can be a substituted or unsubstituted, straight-chain or branched alkenylene group, and examples thereof include an ethenylene group, a 1-propenylene group, a 2-propenylene group, a 1-butenylene group, a 2-butenylene group, a 1-pentenylene group, a 2-pentenylene group, a 1-hexenylene group, a 2-hexenylene group, a 1-heptenylene group, a 2-heptenylene group, a 1-octenylene group, a 2-octenylene group, a 1-nonene- ylene group, a 2-nonenylene group, a 1-decenylene group, a 2-decenylene group, a 1-undecenylene group, a 2-undecenylene group, a 1-dodecenylene group, a 2-dodecenylene group, a 1-tridecenylene group, a 2-tridecenylene group, a 1-tetradecenylene group, a 2-tetradecenylene group, a 1-pentadecenylene group, a 2-pentadecenylene group, a 1-hexadecenylene group, a 2-hexadecenylene group, a 1-heptadecenylene group, a 2-heptadecenylene group, a 1-octadecenylene group, a 2-octadecenylene group, a 1-nonadecenylene group, a 2-nonadecenylene group, a 1-icosene- ylene group, a 2-icosenylene group, and the like, preferably an alkenylene group having 2 to 10 carbon atoms, more preferably an alkenylene group having 2 to 4 carbon atoms.

[0048] In some embodiments, m1 is 2, 3, or 4, and each of n1 and n2 is independently 2 or 3. In some embodiments, m1 is 3 or 4, and each of n1 and n2 is independently 2 or 3. In some embodiments, m1 is 3 or 4, and each of n1 and n2 is independently 2 or 3.

[0049] In some embodiments, R 1 , R 3 , and R 7 are each independently selected from an alkyl group having 1 to 10 carbon atoms, R 2 , R 4 , and R 6 are each independently selected from an alkyl group having 1 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms, and R 5 is selected from an alkylene group having 1 to 10 carbon atoms and an alkenylene group having 2 to 10 carbon atoms.

[0050] In some embodiments, R 1 , R 3 , and R7 each independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, R 2 , R 4 and R 6 each independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and alkenyl groups having 2 to 4 carbon atoms, R 5 is selected from the group consisting of alkylene groups having 1 to 4 carbon atoms and alkenylene groups having 2 to 4 carbon atoms.

[0051] In some embodiments, R 1 , R 3 and R 7 each independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms, R 2 , R 4 and R 6 each independently selected from the group consisting of alkyl groups having 1 to 4 carbon atoms and alkenyl groups having 2 to 4 carbon atoms, R 5 is selected from the group consisting of alkylene groups having 1 to 4 carbon atoms and alkenylene groups having 2 to 4 carbon atoms, m1 is 2, 3 or 4, and n1 and n2 are each independently 2 or 3.

[0052] In some embodiments, the silicon content in the alkylalkoxysilane is 2 wt% to 30 wt%, for example, it can be 2 wt%, 2.3 wt%, 2.7 wt%, 3.1 wt%, 3.4 wt%, 3.7 wt%, 4.1 wt%, 4.3 wt%, 4.6 wt%, 5.1 wt%, 5.3 wt%, 5.7 wt%, 6.1 wt%, 6.3 wt%, 6.8 wt%, 7.1 wt%, 7.3 wt%, 7.8 wt%, 8.1 wt%, 8.5 wt%, 8.8 wt%, 9.3 wt%, 9.5 wt%, 9.7 wt%, 10.1 wt%, 10.4 wt%, 10.7 wt%, 11.1 wt%, 11.4 wt%, 11.5 wt%, 11.9 wt%, 12.2 wt%, 12.6 wt%, 13.0 wt%, 13.5 wt%, 13.9 wt%. The silicon content was 14.4 wt%, 15.0 wt%, 15.5 wt%, 16.1 wt%, 16.8 wt%, 17.1 wt%, 17.5 wt%, 17.6 wt%, 18.4 wt%, 19.3 wt%, 20.3 wt%, 21.3 wt%, 22.6 wt%, 23.9 wt%, 25.4 wt%, 27.1 wt%, 29.1 wt%, and 30 wt%, respectively. The method for detecting silicon content in this application is as follows: Weigh 0.5000 g to 1.0000 g (±0.02 g) of sample, accurately add 0.0001 g to a volumetric flask, add methanol solution, dilute 50 times according to the mass method, shake the sample well to ensure complete dissolution; use an inductively coupled plasma optical emission spectrometer (Avio 200) to determine the emission intensity value of the sample and the emission intensity of the standard working solution; based on the ratio of the emission intensity value of the sample to the emission intensity of the standard working solution, subtract the reagent blank to obtain the mass concentration of the metal element in the sample, and then calculate the content of the metal element in the sample.

[0053] In some embodiments, the hydrocarbon alkoxysilane is selected from one or more of the following: trimethoxymethylsilane, triethoxymethylsilane, oxytrimethylsilane, dimethoxydimethylsilane, trimethoxyethylsilane, 1,2-bistrimethoxysilylethane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxyethylsilane, tetraethoxysilane, tetramethoxysilane, 1,2-bistriethoxysilylethane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0054] In some preferred embodiments, the hydrocarbon alkoxysilane is selected from one or more of the following: trimethoxymethylsilane, trimethoxyethylsilane, 1,2-bistrimethoxysilylethane, triethoxymethylsilane, triethoxyethylsilane, and 1,2-bistriethoxysilylethane.

[0055] In some embodiments, the hydrocarbon alkoxysilane comprises 1,2-bis(trimethoxysilyl)ethane, more preferably 1,2-bis(trimethoxysilyl)ethane. In some embodiments, the hydrocarbon alkoxysilane is a mixture of one or more selected from trimethoxymethylsilane, trimethoxyethylsilane, triethoxymethylsilane, triethoxyethylsilane, and 1,2-bis(triethoxysilyl)ethane with 1,2-bis(trimethoxysilyl)ethane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane and trimethoxyethylsilane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane and triethoxymethylsilane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane and triethoxyethylsilane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane and 1,2-bis(triethoxysilyl)ethane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane and 1,2-bis(trimethoxysilyl)ethane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane, triethoxymethylsilane, and triethoxyethylsilane. In some embodiments, the hydrocarbon alkoxysilane is 1,2-bis(trimethoxysilyl)ethane, trimethoxymethylsilane, and trimethoxyethylsilane.

[0056] In some embodiments, the hydrocarbon alkoxysilane is 1,2-bistrimethoxysilyl ethane and trimethoxymethyl silane, for example, the mass ratio of trimethoxymethyl silane to 1,2-bistrimethoxysilyl ethane is 1:9, 1:4, 3:7, 2:3, 1:1, 3:2, 7:3, 4:1, 9:1, etc.

[0057] This application does not impose any particular limitation on the type of furan resin, nor on its nitrogen content or furfuryl alcohol content, as long as the desired curing effect can be achieved. In some embodiments, the furan resin is selected from one or more of the following: furfuryl alcohol-formaldehyde resin, urea-formaldehyde modified furan resin, phenol-formaldehyde modified furan resin, phenol-urea-formaldehyde modified furan resin, furfuryl ketone resin, and furfuryl ketone-formaldehyde resin. In some embodiments, the furan resin is urea-formaldehyde modified furan resin. In some embodiments, the furan resin is phenol-formaldehyde modified furan resin. In some embodiments, the furan resin is furfuryl alcohol-formaldehyde resin and phenol-urea-formaldehyde modified furan resin. In some embodiments, the furan resin is urea-formaldehyde modified furan resin and phenol-formaldehyde modified furan resin. In some embodiments, the nitrogen content of the furan resin is 0.5 wt% to 5 wt%. In some embodiments, the furfuryl alcohol content of the furan resin is 40 wt% to 90 wt%.

[0058] In this application, furfuryl alcohol formaldehyde resin is a polymer generated by the condensation reaction of furfuryl alcohol and formaldehyde under the action of acidic or alkaline catalysts. Its molecular chain contains active groups such as furan rings (five-membered heterocycles) and hydroxymethyl (–CH2OH), and is characterized by high high-temperature strength, strong corrosion resistance and good moisture resistance.

[0059] In this application, urea-formaldehyde modified furan resin refers to a synthetic resin formed by chemically modifying urea-formaldehyde resin (urea-formaldehyde resin) and furan resin (furfuryl alcohol resin).

[0060] In this application, phenolic modified furan resin refers to a composite resin formed by chemically modifying phenolic resin (phenol-formaldehyde resin) and furan resin (furfuryl alcohol resin), which combines the high-temperature strength and corrosion resistance of furan resin with the heat resistance and bonding stability of phenolic resin.

[0061] In this application, phenol-urea-formaldehyde modified furan resin is a synthetic resin that is chemically modified by combining phenolic resin (phenol-formaldehyde resin), urea-formaldehyde resin (urea-formaldehyde resin) and furan resin (furfuryl alcohol resin). It combines the heat resistance of phenolic resin, the toughness of urea-formaldehyde resin and the high-temperature strength of furan resin. It is widely used as a binder for casting sand molds (cores) and is especially suitable for the production of castings with high requirements for high-temperature performance and crack resistance.

[0062] In this application, furfural acetone resin is an abbreviation for furfural acetone resin, which is a dark brown to black highly viscous liquid or solid, and is prepared by the condensation reaction of furfural and acetone.

[0063] In this application, furfural resin refers to furfural-acetone-formaldehyde resin, which is a thermosetting resin synthesized by polycondensation reaction using furfural, acetone and formaldehyde as the main raw materials. It combines the heat resistance of furfural, the flexibility of acetone and the crosslinking ability of formaldehyde, and is widely used in casting sand mold (core) binders, corrosion-resistant coatings and composite materials.

[0064] In some embodiments, the furan resin and alkylalkoxysilane in the adhesive of this application are mixed. In this embodiment, the mass ratio of furan resin to alkylalkoxysilane can be (1~99):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 34:1, 36:1, 38:1, 40:1, 42:1. The ratios of the components are 44:1, 45:1, 46:1, 48:1, 50:1, 52:1, 55:1, 57:1, 60:1, 63:1, 65:1, 67:1, 70:1, 72:1, 75:1, 78:1, 80:1, 83:1, 85:1, 88:1, 90:1, 92:1, 95:1, 97:1, 99:1, etc., preferably (5~50):1, more preferably (32~50):1. This application controls the mass ratio of furan resin and hydrocarbon alkoxysilane in the single-component binder within the above range, enabling the prepared molding sand to have high tensile strength, high heat resistance and moisture resistance, and low emission of harmful substances during the preparation process. Furthermore, even when the two are mixed and contacted, a rapid reaction does not occur, resulting in good system stability.

[0065] In some embodiments, the furan resin and alkylalkoxysilane in the adhesive of this application are placed separately. In this embodiment, the mass ratio of furan resin to alkylalkoxysilane can be (1~99):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 8:1, 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, 22:1, 24:1, 26:1, 28:1, 30:1, 32:1, 34:1, 36:1, 38:1, 40:1, 42:1. The ratios of furan resin and hydrocarbon alkoxysilane in the two-component binder are 44:1, 45:1, 46:1, 48:1, 50:1, 52:1, 55:1, 57:1, 60:1, 63:1, 65:1, 67:1, 70:1, 72:1, 75:1, 78:1, 80:1, 83:1, 85:1, 88:1, 90:1, 92:1, 95:1, 97:1, 99:1, etc., preferably (5~50):1, more preferably (5~20):1. This application controls the mass ratio of furan resin and hydrocarbon alkoxysilane in the two-component binder within the above range, enabling the prepared foundry sand to have high tensile strength, high heat resistance, and moisture resistance, while also minimizing the emission of harmful substances during the preparation process.

[0066] On the other hand, this application also provides the use of furan resin and / or hydrocarbon alkoxysilane in the preparation of two-component furan resin adhesives for molding; wherein the furan resin is any of the aforementioned furan resins, and the hydrocarbon alkoxysilane is any of the aforementioned hydrocarbon alkoxysilanes.

[0067] In this application, recyclability refers to the reusability of molding sand after the use of binder, which can be evaluated by the strength, loss on ignition, acid consumption value, etc. of the molding sand.

[0068] In another aspect, this application also provides a two-component furan resin adhesive kit for molding, comprising agent A and agent B, agent A comprising any of the aforementioned furan resins, and agent B comprising any of the aforementioned hydrocarbon alkoxysilanes.

[0069] In some embodiments, the two-component furan resin adhesive kit for molding of this application consists of agent A and agent B.

[0070] Furthermore, this application also provides a method for preparing molding sand for casting, which includes the following steps:

[0071] A two-component molding furan resin binder and curing agent containing furan resin and hydrocarbon alkoxysilane are added to refractory aggregate and mixed to obtain a mixture. The mixture is then placed in a mold for curing to obtain molding sand for casting.

[0072] The two-component furan resin adhesive for molding is any of the aforementioned two-component furan resin adhesives for molding.

[0073] This application does not impose any particular limitation on the type of refractory aggregate, which can be any conventional refractory aggregate in the art. For example, refractory aggregate can be silica sand, artificial sand containing silica and alumina, zircon sand, chromite sand, olivine sand, magnesia sand, corundum sand, etc.

[0074] In some implementations, the refractory aggregate of this application can be either new sand or recycled sand.

[0075] This application does not impose any particular limitation on the type and amount of curing agent, as long as the desired curing effect can be achieved. In some embodiments, the curing agent may be any one or more of the following: p-toluenesulfonic acid, xylenesulfonic acid, sulfuric acid, methyl sulfate, ethyl sulfate, phosphoric acid, and lactic acid, etc.

[0076] In some embodiments, the curing agent may be 15wt% to 100wt% of the two-component furan resin adhesive for molding of this application, for example, it may be 15wt%, 20wt%, 23wt%, 25wt%, 28wt%, 30wt%, 32wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%, etc., preferably 20wt% to 70wt%, more preferably 30wt% to 60wt%.

[0077] In some embodiments, the two-component furan resin binder for molding accounts for 0.5wt% to 3wt% of the refractory aggregate, for example, it can be 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.7wt%, 2.8wt%, 2.9wt%, 3wt%, etc., preferably 0.7wt% to 1.5wt%.

[0078] Example

[0079] The manufacturers and product models of the raw materials used in this embodiment are shown in Table 1 below. Unless otherwise specified, all raw materials used can be obtained commercially.

[0080] Table 1

[0081]

[0082] In this embodiment, figure-eight samples were prepared according to the method in section 5.6 of the national standard GB-T 2684-2009 "Test Methods for Foundry Sand and Mixtures". The tensile strength of various molding sands at different times (1 hour, 4 hours, 24 hours) was tested. The test conditions were according to Appendix C of JB / T7526-2008 "Self-hardening Furan Resin for Foundry". The test conditions for high wet strength were: sand temperature 20℃±2℃; room temperature 20℃±2℃; relative humidity (85±5)%, and other conditions the same as for normal tensile strength. Among them, the 1-hour tensile strength can reflect the curing speed.

[0083] In this embodiment, the high-temperature performance of each molding sand was tested at the JT-SJZ-1 core sand testing workstation (Beijing Jiatian Foundry Technology Co., Ltd.). The mixed sand was placed into the mold to prepare the core sand. For 10mm molding sand samples, the samples should be demolded only when they have cured to the point where they can be removed from the mold. The samples should be placed in a desiccator for 24 hours. The test conditions are a pressure of 2MPa and a temperature of 1000℃. The heat resistance time of the samples under these conditions should be tested.

[0084] In this embodiment, the method for detecting formaldehyde release from furan resin is as follows: Formaldehyde released during the curing reaction of the resin curing agent is absorbed into a certain mass of distilled water using an absorption device. The test employs the acetylacetone method for color development; formaldehyde reacts with acetylacetone to produce a yellow color. The absorbance of the solution after color development is measured using a UV spectrophotometer to determine the concentration of formaldehyde in the aqueous solution, thereby calculating the formaldehyde release per gram of furan resin.

[0085] Unless otherwise stated, all numbers in this application refer to parts by mass, and all percentages refer to percentages by mass.

[0086] Example 1

[0087] Using a specific two-component resin metering device, 0.5 parts of curing agent (GS03), 0.91 parts of urea-formaldehyde modified furan resin (with a nitrogen content of 3 wt% and a furfuryl alcohol content of 80 wt%), and 0.09 parts of hydrocarbon alkoxysilane (1,2-bis(trimethoxysilyl ethane)) are sequentially added to a sand mixer to ensure that the curing agent, urea-formaldehyde modified furan resin, hydrocarbon alkoxysilane, and 100 parts of refractory aggregate (new silica sand with a silica content of 90%-93%) are mixed evenly to obtain a mixture. The mixture is then placed in a mold for curing to obtain molding sand for casting.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 1 is that no hydrocarbon alkoxysilane is added, and the urea-formaldehyde modified furan resin accounts for 1 wt% of the refractory aggregate.

[0090] Example 2

[0091] The difference between this embodiment and Embodiment 1 is that the mass ratio of urea-formaldehyde modified furan resin to hydrocarbon alkoxysilane is 19:1.

[0092] Example 3

[0093] The difference between this embodiment and Embodiment 1 is that the mass ratio of urea-formaldehyde modified furan resin to hydrocarbon alkoxysilane is 17:3.

[0094] Example 4

[0095] The difference between this embodiment and Embodiment 1 is that the mass ratio of urea-formaldehyde modified furan resin to hydrocarbon alkoxysilane is 5:1.

[0096] Example 5

[0097] The difference between this embodiment and Embodiment 1 is that the urea-formaldehyde modified furan resin is replaced with phenol-formaldehyde modified furan resin, which has a nitrogen content of 0.5 wt% and a furfuryl alcohol content of 80 wt%.

[0098] Example 6

[0099] The difference between this embodiment and Example 1 is that the hydrocarbon alkoxysilane is a mixture obtained by mixing trimethoxymethylsilane and 1,2-bistrimethoxysilylethane in a mass ratio of 7:3.

[0100] Example 7

[0101] The difference between this embodiment and Example 1 is that the hydrocarbon alkoxysilane is a mixture obtained by mixing trimethoxymethylsilane and 1,2-bistrimethoxysilylethane in a mass ratio of 2:8.

[0102] Example 8

[0103] The difference between this embodiment and Embodiment 1 is that the mass ratio of urea-formaldehyde modified furan resin to hydrocarbon alkoxysilane is 99:1.

[0104] Example 9

[0105] The difference between this embodiment and Embodiment 1 is that the mass ratio of urea-formaldehyde modified furan resin to hydrocarbon alkoxysilane is 49:1.

[0106] Example 10

[0107] The difference between this embodiment and Embodiment 1 is that the hydrocarbon alkoxysilane is trimethoxymethylsilane.

[0108] Example 11

[0109] The difference between this embodiment and Embodiment 1 is that the hydrocarbon alkoxysilane is dimethoxydimethylsilane.

[0110] Example 12

[0111] The difference between this embodiment and Embodiment 1 is that the hydrocarbon alkoxysilane is 1,2-bis(triethoxysilyl ethane).

[0112] Example 13

[0113] First, 0.97 parts of urea-formaldehyde modified furan resin (with a nitrogen content of 3 wt% and a furfuryl alcohol content of 80 wt%) and 0.03 parts of hydrocarbon alkoxysilane (1,2-bis(trimethoxysilyl ethane)) are mixed 24 hours in advance to obtain a mixture. In a sand mixer, 0.5 parts of curing agent (GS03), 0.97 parts of urea-formaldehyde modified furan resin and 0.03 parts of hydrocarbon alkoxysilane are added to the equipment in sequence through a specific device, so that the mixture of curing agent, urea-formaldehyde modified furan resin and hydrocarbon alkoxysilane is mixed evenly with 100 parts of refractory aggregate (new silica sand with a silica content of 90%-93%) to obtain a mixture. The mixture is then placed in a mold for curing to obtain molding sand for casting.

[0114] Comparative Example 2

[0115] The difference between Comparative Example 2 and Example 1 is that the urea-formaldehyde modified furan resin is replaced with basic phenolic resin, and the curing agent is triacetin.

[0116] The raw materials and dosages of the above embodiments and comparative examples, as well as the performance parameters of the final casting sand, are listed in Table 2 below.

[0117] Table 2

[0118]

[0119]

[0120]

[0121] The above description is merely a preferred embodiment of this application and is not intended to limit the application in any other way. Any person skilled in the art may make changes or modifications to the disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the protection scope of this application.

Claims

1. A two-component furan resin binder for molding, comprising: a furan resin and a hydrocarbyl alkoxysilane; the hydrocarbyl alkoxysilane comprises 1, 2-bistrimethoxysilylethane, or comprises 1, 2-bistrimethoxysilylethane and a compound represented by the following formula (I) : (OR 1 ) m1 (R 2 ) 4-m1 Si formula (I), wherein R 1 each independently is selected from the group consisting of an alkyl group having 1 to 20 carbon atoms, R 2 each independently is selected from the group consisting of an alkyl group having 1 to 20 carbon atoms and an alkenyl group having 2 to 20 carbon atoms, and m1 is 1, 2, 3 or 4; a mass ratio of the furan resin to the hydrocarbyl alkoxysilane is (5-50) :

1.

2. The furan resin binder for two-component molding according to claim 1, wherein R 1 each independently is selected from the group consisting of an alkyl group having a carbon number of 1 to 10.

3. The furan resin binder for two-component molding according to claim 1 or 2, wherein R 2 each independently is selected from the group consisting of an alkyl group having 1 to 10 carbon atoms and an alkenyl group having 2 to 10 carbon atoms.

4. The furan resin binder for two-component molding according to claim 1 or 2, wherein m1 is 2, 3 or 4.

5. The furan resin binder for two-component molding according to claim 1 or 2, wherein a content of silicon in the hydrocarbyl alkoxysilane is 2wt%-30wt%.

6. The furan resin binder for two-component molding according to claim 1 or 2, wherein the hydrocarbyl alkoxysilane further comprises one or more than two selected from the group consisting of trimethoxymethylsilane, triethoxymethylsilane, methoxytrimethylsilane, dimethoxydimethylsilane, trimethoxyethylsilane, ethoxytrimethylsilane, diethoxydimethylsilane, triethoxyethylsilane, tetraethoxysilane, tetramethoxysilane, 1, 2-bistrimethoxysilylethane, vinyltrimethoxysilane and vinyltriethoxysilane.

7. The furan resin binder for two-component molding according to claim 1 or 2, wherein the furan resin is one or more than two selected from the group consisting of furfuryl alcohol formaldehyde resin, urea formaldehyde modified furan resin, phenol formaldehyde modified furan resin, phenol urea formaldehyde modified furan resin, furfural resin, furfuraldehyde resin.

8. The furan resin binder for two-component molding according to claim 1 or 2, wherein the furan resin and the hydrocarbyl alkoxysilane are placed separately or mixedly. 9.Use of a furan resin and / or a hydrocarbyl alkoxysilane in the preparation of a two-component furan resin binder for molding, wherein the furan resin and the hydrocarbyl alkoxysilane are as defined in any one of claims 1-7. 10.A two-component furan resin binder kit for molding, comprising an A agent and a B agent, the A agent comprising a furan resin as defined in any one of claims 1-7, and the B agent comprising a hydrocarbyl alkoxysilane as defined in any one of claims 1-7.

11. A method of producing molding sand for casting, wherein, the method comprises the following steps: adding the two-component furan resin binder for molding comprising the furan resin and the hydrocarbyl alkoxysilane and a curing agent into refractory aggregate to obtain a mixed material, and placing the mixed material into a mold to cure, to obtain a molding sand for casting; wherein the two-component furan resin binder for molding is as defined in any one of claims 1-7.

12. The production method according to claim 11, wherein the two-component furan resin binder for molding accounts for 0.5wt%-3wt% of the refractory aggregate.

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