Furan resin for hot core box and preparation method and use method thereof

Abstract

The invention relates to a furan resin for a hot core box, which comprises, by weight percentage, 5% to 15% solid formaldehyde, 1% to 3% modified starch, 3% to 10% liquid formaldehyde, 2% to 13% urea, 0.4% to 0.8% silane coupling agent, 60% to 90% furfuryl alcohol, 0.5% to 1.5% wetting agent and 7% to 16% accelerator. The invention also discloses a preparation and use method of the furan resin for a hot core box. The furan resin for a hot core box disclosed by the invention adopts a combination of solid formaldehyde and liquid formaldehyde, effectively controls the addition of external water to the target product, does not require dehydration during the preparation process, has high production efficiency and good environmental performance; and is cured with an acidic curing agent for two-component curing, so that the obtained resin sand can be used for a long time. In the process of hot core box core making, no irritating gas is volatilized, which improves the on-site working environment, and the obtained sand core has high strength, good toughness, is not easy to break and has good appearance quality.

Description

Technical Field

[0001] The invention relates to the technical field of casting auxiliary materials, in particular to a furan resin for a hot core box and a preparation method and a use method thereof. Background Art

[0002] The hot core box furan resin core making process provides a very effective method for the rapid production of medium and small sand cores with high dimensional accuracy. It is widely used in large-scale production of small and medium-sized sand cores in similar industries such as automobiles and tractors. The hot core box core making process uses liquid thermosetting resin and catalyst to prepare core sand, and uses a core shooting machine to shoot the mixed core sand into the metal core box, and heats the sand core at 180℃~250℃ to harden it.

[0003] The core sand premixed with furan resin and curing agent should not be sticky and cured before core shooting. This situation requires the core sand to be usable for as long as possible. After the core sand is shot, it must be hardened by high temperature heating, which will release irritating gases during the process. Summary of the invention

[0004] Based on this, it is necessary to provide a furan resin for hot core boxes with long usable time, low free formaldehyde, high strength and good environmental performance, as well as a preparation method and a use method thereof, in order to address the technical problems that the core sand prepared with existing furan resin has a short usable time and a pungent odor.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] The embodiment of the present invention discloses a furan resin for a hot core box, which comprises, by weight percentage, 5% to 15% of solid formaldehyde, 1% to 3% of modified starch, 3% to 10% of liquid formaldehyde, 2% to 13% of urea, 0.4% to 0.8% of a silane coupling agent, 60% to 90% of furfuryl alcohol, 0.5% to 1.5% of a wetting agent and 7% to 16% of an accelerator.

[0007] In one embodiment, the modified starch is a composite modified starch.

[0008] In one embodiment, the modified starch is one or more of acid-hydrolyzed starch, cross-linked starch, esterified starch, etherified starch, α-, β-, γ-cyclodextrin, and maltodextrin.

[0009] In one embodiment, the concentration of the solid formaldehyde is 95% to 97%.

[0010] In one embodiment, the liquid formaldehyde is a formaldehyde aqueous solution with a formaldehyde content of 36.5% to 37.5%.

[0011] In one embodiment, the wetting agent is one or more of alkylphenol polyether, isomeric tridecanol ether, fatty acid methyl ester ethoxylate, and secondary alcohol polyether.

[0012] In one embodiment, the promoter is xylitol mother solution.

[0013] Furthermore, the xylitol mother liquor is one or more of sorbitol mother liquor, arabitol mother liquor, and galactitol mother liquor.

[0014] In a second aspect, an embodiment of the present invention further discloses a preparation method, which is applied to any of the above-mentioned furan resins for hot core boxes, comprising the following steps:

[0015] S1. Add liquid formaldehyde into the reactor, stir, add solid formaldehyde, modified starch, furfuryl alcohol, and urea in sequence, adjust the pH value of the liquid to 8-10, raise the temperature to 90°C-96°C, and keep warm;

[0016] S2, cool down to 65℃~75℃, add furfuryl alcohol, adjust the pH value of the liquid to 4.6~5.0, heat up to 96℃~106℃, and keep warm;

[0017] S3, cool down to 75℃~85℃, add accelerator and stir;

[0018] S4, cooling to 35° C. to 45° C., adding a wetting agent and a silane coupling agent in sequence, stirring, and obtaining the furan resin.

[0019] In one embodiment, in the step S1, the amount of furfuryl alcohol added is 15% to 25%; in the step S2, the amount of furfuryl alcohol added is 45% to 65%.

[0020] In one embodiment, in step S1, an alkali solution is used to adjust the pH value of the feed solution.

[0021] Furthermore, the alkali solution is an aqueous solution of potassium hydroxide.

[0022] Furthermore, the concentration of the potassium hydroxide aqueous solution is 35% to 45%.

[0023] In one embodiment, in step S2, an acid solution is used to adjust the pH value of the feed solution.

[0024] Furthermore, the acid solution includes hydrochloric acid, formic acid and water.

[0025] Furthermore, the weight ratio of the raw material components of the acid solution is hydrochloric acid: formic acid: water = 3:3:4.

[0026] In one embodiment, in the step S1, the temperature is raised to 90° C. to 96° C. over 40 min to 60 min, and kept at this temperature for 65 min to 75 min.

[0027] In one embodiment, in the step S2, the temperature is raised to 96° C. to 106° C. over 60 to 80 minutes, and kept at this temperature for 85 to 95 minutes.

[0028] In one embodiment, in the step S3, the time is 25 min to 35 min.

[0029] In one embodiment, in the step S4, the time is 25 min to 35 min.

[0030] In a third aspect, an embodiment of the present invention further discloses a method of use, which is applied to any of the above-mentioned furan resins for hot core boxes, wherein the furan resin for hot core boxes is used in combination with an acidic curing agent, and the amount of the acidic curing agent added is 15% to 40% of the amount of the furan resin added for hot core boxes.

[0031] Furthermore, the amount of the furan resin added to the hot core box is 1.5% to 2.5% of the weight of the sand.

[0032] Furthermore, the hot box heating temperature is 180°C to 250°C.

[0033] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0034] The furan resin for the hot core box disclosed by the present invention adopts a combination of solid formaldehyde and liquid formaldehyde, effectively controls the addition of external water to the target product, does not require dehydration during the preparation process, has high production efficiency and good environmental performance; the furan resin for the hot core box disclosed by the present invention is combined with an acidic curing agent for two-component curing, and the prepared resin sand can be used for a long time. During the hot core box core making process, no irritating gas is volatilized, which improves the on-site working environment, and the prepared sand core has high strength, good toughness, is not easy to break and has good appearance quality. DETAILED DESCRIPTION

[0035] For ease of understanding of the present invention, the present invention will be described more fully below with reference to relevant embodiments. Preferred embodiments of the present invention are provided in the embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] One of the purposes of the present invention is to disclose a furan resin for hot core box, wherein the furan resin for hot core box disclosed comprises, by weight percentage, 5% to 15% solid formaldehyde, 1% to 3% modified starch, 3% to 10% liquid formaldehyde, 2% to 13% urea, 0.4% to 0.8% silane coupling agent, 60% to 90% furfuryl alcohol, 0.5% to 1.5% wetting agent and 7% to 16% accelerator. Specifically, the modified starch is a composite modified starch, which can extend the usable time of resin sand mixed with the furan resin for hot core box of the present invention and the curing agent matched therewith by at least 50%, slow down the stickiness speed of the resin sand in the core shooting molding / core process, and have a longer storage time, so that the operation is convenient, and the appearance quality of the obtained sand core is good. The concentration of solid formaldehyde is 95% to 97%, and the liquid formaldehyde is a formaldehyde aqueous solution with a content of 36.5% to 37.5%. The solid formaldehyde and liquid formaldehyde are combined to effectively control the addition of external water to the target product. The preparation process does not require dehydration, and has high production efficiency and good environmental performance. The accelerator is xylitol mother liquor. The xylitol mother liquor is modified to enhance the flexibility of the resin. In the resin sand core shooting production process, the resin sand has good toughness, high sand core strength, and is not easy to break. The wetting agent is one or more of alkylphenol polyethers, isomeric tridecanol ethers, fatty acid methyl ester ethoxylates, and secondary alcohol polyethers. Adding a wetting agent for modification can reduce the volatilization of the resin, and there is no irritating odor, which improves the working site environment during the hot core box core making process.

[0038] The second object of the present invention is to disclose a method for preparing the above-mentioned furan resin for hot box, comprising the following steps:

[0039] S1. Add 3% to 10% liquid formaldehyde into a reaction kettle, start a stirrer, add 5% to 15% solid formaldehyde, 1% to 3% modified starch, 15% to 25% furfuryl alcohol, and 2% to 13% urea in sequence, and adjust the pH value of the feed liquid to 8 to 10 with alkali solution.

[0040] S2. Heat the temperature to 90℃~96℃ in 40min~60min by steam, and keep it warm for 65min~75min.

[0041] S3. Cool the mixture to 65-75°C with cooling water, add 45%-65% furfuryl alcohol, and adjust the pH value of the solution to 4.6-5.0 with acid solution.

[0042] S4. Heat the temperature to 96℃~106℃ in 60min~80min through steam, and keep the temperature for 85min~95min.

[0043] S5. Cool down to 75°C-85°C, add 7%-16% accelerator, and stir for 25min-35min.

[0044] S6. Cool down to 35°C to 45°C, add 0.5% to 1.5% wetting agent and 0.4% to 0.8% silane coupling agent in sequence, and stir for 25min to 35min.

[0045] S7. Take samples for inspection, and after passing the inspection, measure and package.

[0046] Specifically, the alkali solution can be a potassium hydroxide aqueous solution, and its concentration is preferably 35% to 45%; the acid solution can be a mixed acid aqueous solution of hydrochloric acid, formic acid and water in a weight ratio of 3:3:4. Of course, the present invention can also select alkali solutions and acid solutions with other components and proportions, as long as the pH value of the feed liquid can be adjusted and it does not conflict with the raw materials of the present invention, and the present invention is not limited to this.

[0047] The third object of the present invention is to disclose a method for using the above-mentioned furan resin for hot core box. The furan resin for hot core box is used in combination with an acidic curing agent. The furan resin for hot core box of the present invention and the acidic curing agent are mixed into the mold / core sand in a certain proportion to achieve two-component curing.

[0048] Specifically, the amount of the acidic curing agent added may be 15% to 40% of the amount of the furan resin added for the hot box, and the amount of the furan resin added for the hot box may be 1.5% to 2.5% of the weight of the mold / core sand.

[0049] Furthermore, resin sand mixed with resin and curing agent is put into the core box for core making, and the usable time of the resin sand is ≥2h; the heating temperature of the core box can be 180°C to 250°C, and the heating time can be 60s to 120s. Example

[0050] A furan resin for hot core box, the raw materials include: 10kg solid formaldehyde, 2kg modified starch, 6kg liquid formaldehyde, 4kg urea, 1kg silane coupling agent, 144kg furfuryl alcohol, 1kg wetting agent and 32kg accelerator

[0051] It should be noted that, in this embodiment, the concentration of solid formaldehyde can be 96%, the liquid formaldehyde can be a 37% formaldehyde aqueous solution; the deformed starch can be acid-decomposed starch, the wetting agent can be alkylphenol polyether, and the accelerator can be xylitol mother liquor.

[0052] The method for preparing the furan resin for hot box of this embodiment specifically comprises the following steps:

[0053] S1. Add 6 kg of liquid formaldehyde into the reactor, start the stirrer, add 10 kg of solid formaldehyde, 2 kg of modified starch, 30 kg of furfuryl alcohol, and 4 kg of urea in sequence, and adjust the pH value of the feed liquid to 8 with alkali solution.

[0054] It should be noted that the alkali solution in this embodiment is a 40% potassium hydroxide aqueous solution.

[0055] S2. Heat the temperature to 92°C in 42 minutes with steam, and keep the temperature for 70 minutes.

[0056] S3. Cool the mixture to 70°C with cooling water, add 114 kg of furfuryl alcohol, and adjust the pH value of the solution to 4.6 with acid solution.

[0057] It should be noted that the acid solution in this embodiment is a mixed acid aqueous solution of hydrochloric acid, formic acid and water in a weight ratio of 3:3:4.

[0058] S4. Heat the temperature to 98°C in 65 minutes and keep it warm for 90 minutes.

[0059] S5. Cool down to 80°C, add 32 kg of accelerator, and stir for 30 minutes.

[0060] S6. Cool down to 40°C, add 1 kg of wetting agent and 1 kg of silane coupling agent in sequence, and stir for 30 minutes.

[0061] S7. Take samples for inspection, and after passing the inspection, measure and package.

[0062] In this embodiment, the furan resin for the hot box was sampled and tested, and the free formaldehyde content was 0.25%, the density was 1.149 g / ml, the viscosity at 20° C. was 32.4 mPa·s, the nitrogen content was 1.3%, and the water content was 5.8%.

[0063] Take the furan resin for hot core box of this embodiment and acid curing agent, add them into the foundry sand and mix them evenly to obtain resin sand. The resin sand can be used for 110 minutes, the VOC of the resin sand is 10.9 mg / m 3 , and the 2h tensile strength of the test block made of the resin sand is 3.52 MPa.

[0064] Specifically, the amount of the furan resin added for the hot box in this embodiment is 2.0% of the weight of the casting sand, and the amount of the acidic curing agent added is 25% of the amount of the furan resin added for the hot box. Example

[0065] A furan resin for a hot core box comprises, by weight percentage, 10 kg of solid formaldehyde, 2 kg of modified starch, 6 kg of liquid formaldehyde, 26 kg of urea, 1 kg of silane coupling agent, 140 kg of furfuryl alcohol, 1 kg of wetting agent and 14 kg of accelerator.

[0066] It should be noted that, in this embodiment, the concentration of solid formaldehyde can be 97%, the liquid formaldehyde can be a formaldehyde aqueous solution with a content of 37.5%; the deformed starch can be etherified starch, the wetting agent can be fatty acid methyl ester ethoxylate and secondary alcohol polyether in a mass ratio of 1:1, and the promoter can be xylitol mother liquor.

[0067] The method for preparing the furan resin for hot box of this embodiment specifically comprises the following steps:

[0068] S1. Add 6 kg of liquid formaldehyde into the reactor, start the stirrer, add 10 kg of solid formaldehyde, 2 kg of modified starch, 50 kg of furfuryl alcohol, and 26 kg of urea in sequence, and adjust the pH value of the feed liquid to 10 with alkali solution.

[0069] It should be noted that the alkali solution in this embodiment can be a 45% potassium hydroxide aqueous solution.

[0070] S2. Heat the temperature to 96°C in 50 minutes with steam, and keep the temperature for 75 minutes.

[0071] S3. Cool the mixture to 75°C with cooling water, add 90 kg of furfuryl alcohol, and adjust the pH value of the solution to 5.0 with acid solution.

[0072] It should be noted that the acid solution in this embodiment can be a mixed acid aqueous solution of hydrochloric acid, formic acid and water in a weight ratio of 3:3:4.

[0073] S4. Heat the temperature to 106°C in 78 minutes with steam, and keep the temperature for 85 minutes.

[0074] S5. Cool down to 75°C, add 14 kg of accelerator, and stir for 30 minutes.

[0075] S6. Cool down to 45°C, add 1 kg of wetting agent and 1 kg of silane coupling agent in sequence, and stir for 35 minutes.

[0076] S7. Take samples for inspection, and after passing the inspection, measure and package.

[0077] In this embodiment, the furan resin for the hot box was sampled and tested, and the free formaldehyde content was 0.27%, the density was 1.152 g / ml, the viscosity at 20° C. was 43.8 mPa·s, the nitrogen content was 6.2%, and the water content was 8.4%.

[0078] Take the furan resin for hot core box of this embodiment and acid curing agent, add them into the foundry sand and mix them evenly to obtain resin sand. The resin sand can be used for 100 minutes, the VOC of the resin sand is 12.2 mg / m 3 , and the 2h tensile strength of the test block made of the resin sand is 2.36 MPa.

[0079] Specifically, the amount of the furan resin added for the hot box in this embodiment is 1.5% of the weight of the casting sand, and the amount of the acidic curing agent added is 15% of the amount of the furan resin added for the hot box. Example

[0080] A furan resin for a hot core box comprises, by weight percentage, 29.4 kg of solid formaldehyde, 6 kg of modified starch, 20 kg of liquid formaldehyde, 4 kg of urea, 1.6 kg of silane coupling agent, 120 kg of furfuryl alcohol, 3 kg of wetting agent and 16 kg of accelerator.

[0081] It should be noted that, in this embodiment, the concentration of solid formaldehyde can be 95%, the liquid formaldehyde can be a 36.5% formaldehyde aqueous solution; the deformed starch can be maltodextrin, the wetting agent can be fatty acid methyl ester ethoxylate, and the promoter can be xylitol mother liquor.

[0082] The method for preparing the furan resin for hot box of this embodiment specifically comprises the following steps:

[0083] S1. Add 20 kg of liquid formaldehyde into the reactor, start the stirrer, add 29.4 kg of solid formaldehyde, 6 kg of modified starch, 30 kg of furfuryl alcohol, and 4 kg of urea in sequence, and adjust the pH value of the feed liquid to 9 with alkali solution.

[0084] It should be noted that the alkali solution in this embodiment can be a 35% potassium hydroxide aqueous solution.

[0085] S2. Heat the temperature to 96°C in 50 minutes with steam, and keep the temperature for 75 minutes.

[0086] S3. Cool the mixture to 70°C with cooling water, add 90 kg of furfuryl alcohol, and adjust the pH value of the solution to 4.6 with acid solution.

[0087] It should be noted that the acid solution in this embodiment can be a mixed acid aqueous solution of hydrochloric acid, formic acid and water in a weight ratio of 3:3:4.

[0088] S4. Heat the temperature to 104°C in 65 minutes with steam, and keep the temperature for 80 minutes.

[0089] S5. Cool down to 83°C, add 16 kg of accelerator, and stir for 25 minutes.

[0090] S6. Cool down to 45°C, add 3 kg of wetting agent and 1.6 kg of silane coupling agent in sequence, and stir for 25 minutes.

[0091] S7. Take samples for inspection, and after passing the inspection, measure and package.

[0092] In this embodiment, the furan resin for the hot box was sampled and tested, and the free formaldehyde content was 0.29%, the density was 1.154 g / ml, the viscosity at 20° C. was 36.4 mPa·s, the nitrogen content was 1.9%, and the moisture content was 7.3%.

[0093] Take the furan resin for hot core box of this embodiment and acid curing agent, add them into the foundry sand and mix them evenly to obtain resin sand. The resin sand can be used for 105 minutes, the VOC of the resin sand is 11.4 mg / m 3 , and the 2h tensile strength of the test block made of the resin sand is 3.04 MPa.

[0094] Specifically, the amount of the furan resin added for the hot box in this embodiment is 2.5% of the weight of the casting sand, and the amount of the acidic curing agent added is 40% of the amount of the furan resin added for the hot box. Example

[0095] A furan resin for a hot core box comprises, by weight percentage, 10 kg of solid formaldehyde, 6 kg of modified starch, 20 kg of liquid formaldehyde, 4 kg of urea, 1.6 kg of silane coupling agent, 123.4 kg of furfuryl alcohol, 3 kg of wetting agent and 32 kg of accelerator.

[0096] It should be noted that, in this embodiment, the concentration of solid formaldehyde can be 96%, the liquid formaldehyde can be a 37% formaldehyde aqueous solution; the deformed starch can be acid-hydrolyzed starch, the wetting agent can be isomeric tridecyl alcohol ether, and the accelerator can be xylitol mother liquor.

[0097] The method for preparing the furan resin for hot box of this embodiment specifically comprises the following steps:

[0098] S1. Add 20 kg of liquid formaldehyde into the reactor, start the stirrer, add 10 kg of solid formaldehyde, 6 kg of modified starch, 30 kg of furfuryl alcohol, and 4 kg of urea in sequence, and adjust the pH value of the liquid to 9 with alkali solution.

[0099] It should be noted that the alkali solution in this embodiment can be a 40% potassium hydroxide aqueous solution.

[0100] S2. Heat the temperature to 94°C in 50 minutes with steam, and keep the temperature for 70 minutes.

[0101] S3. Cool the mixture to 75°C with cooling water, add 93.4 kg of furfuryl alcohol, and adjust the pH value of the solution to 4.8 with acid solution.

[0102] It should be noted that the acid solution in this embodiment can be a mixed acid aqueous solution of hydrochloric acid, formic acid and water in a weight ratio of 3:3:4.

[0103] S4. Heat the temperature to 101°C in 70 minutes with steam, and keep the temperature for 80 minutes.

[0104] S5. Cool down to 80°C, add 32 kg of accelerator, and stir for 30 minutes.

[0105] S6. Cool down to 40°C, add 3 kg of wetting agent and 1.6 kg of silane coupling agent in sequence, and stir for 30 minutes.

[0106] S7. Take samples for inspection, and after passing the inspection, measure and package.

[0107] In this embodiment, the furan resin for the hot box was sampled and tested, and the free formaldehyde content was 0.24%, the density was 1.151 g / ml, the viscosity at 20° C. was 36.1 mPa·s, the nitrogen content was 1.4%, and the water content was 6.5%.

[0108] Take the furan resin for hot core box of this embodiment and acid curing agent, add them into the foundry sand and mix them evenly to obtain resin sand. The resin sand can be used for 130 minutes, the VOC of the resin sand is 9.5 mg / m 3 , and the 2h tensile strength of the test block made of the resin sand is 3.27 MPa.

[0109] Specifically, the amount of the furan resin added for the hot box in this embodiment is 2% of the weight of the casting sand, and the amount of the acidic curing agent added is 25% of the amount of the furan resin added for the hot box.

[0110] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a furan resin for a hot box, characterized in that: The furan resin for the hot core box comprises, by weight percentage, 5% to 15% solid formaldehyde, 1% to 3% modified starch, 3% to 10% liquid formaldehyde, 2% to 13% urea, 0.4% to 0.8% silane coupling agent, 60% furfuryl alcohol, 0.5% to 1.5% wetting agent and 7% to 16% accelerator; The modified starch is one or more of acid-decomposed starch, cross-linked starch, esterified starch, etherified starch, α-, β-, γ-cyclodextrin, and maltodextrin; The accelerator is xylitol mother liquor; The method for preparing the furan resin for the hot box comprises the following steps: S1. Add liquid formaldehyde into the reactor, stir, add solid formaldehyde, modified starch, furfuryl alcohol, and urea in sequence, adjust the pH value of the liquid to 8-10, raise the temperature to 90°C-96°C, and keep warm; S2, cool down to 65℃~75℃, add furfuryl alcohol, adjust the pH value of the liquid to 4.6~5.0, heat up to 96℃~106℃, and keep warm; S3, cool down to 75℃~85℃, add accelerator and stir; S4, cooling to 35° C. to 45° C., adding a wetting agent and a silane coupling agent in sequence, stirring, and obtaining the furan resin.

2. The method for preparing a furan resin for a hot box according to claim 1, wherein: The concentration of the solid formaldehyde is 95% to 97%.

3. The method for preparing a furan resin for a hot box according to claim 1, wherein: The liquid formaldehyde is a formaldehyde aqueous solution with a content of 36.5% to 37.5%.

4. The method for preparing a furan resin for a hot box according to claim 1, wherein: The wetting agent is one or more of alkylphenol polyether, isomeric tridecanol ether, fatty acid methyl ester ethoxylate, and secondary alcohol polyether.