CN112126028A - Production method of expandable phenolic resin for precoated sand - Google Patents
Production method of expandable phenolic resin for precoated sand Download PDFInfo
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- CN112126028A CN112126028A CN202011008714.9A CN202011008714A CN112126028A CN 112126028 A CN112126028 A CN 112126028A CN 202011008714 A CN202011008714 A CN 202011008714A CN 112126028 A CN112126028 A CN 112126028A
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- precoated sand
- phenolic resin
- coupling agent
- mass ratio
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- 239000004576 sand Substances 0.000 title claims abstract description 93
- 239000005011 phenolic resin Substances 0.000 title claims abstract description 82
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 title claims abstract description 74
- 229920001568 phenolic resin Polymers 0.000 title claims abstract description 72
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 33
- 239000007822 coupling agent Substances 0.000 claims abstract description 55
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000003607 modifier Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims description 47
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 39
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 39
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 36
- 150000001412 amines Chemical class 0.000 claims description 29
- 238000003756 stirring Methods 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 27
- 150000001282 organosilanes Chemical group 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 21
- JLTDJTHDQAWBAV-UHFFFAOYSA-N N,N-dimethylaniline Chemical compound CN(C)C1=CC=CC=C1 JLTDJTHDQAWBAV-UHFFFAOYSA-N 0.000 claims description 20
- 239000002202 Polyethylene glycol Substances 0.000 claims description 19
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 19
- 229920002401 polyacrylamide Polymers 0.000 claims description 19
- 229920001223 polyethylene glycol Polymers 0.000 claims description 19
- 239000011701 zinc Substances 0.000 claims description 19
- 229910052725 zinc Inorganic materials 0.000 claims description 19
- 238000001816 cooling Methods 0.000 claims description 17
- 235000006408 oxalic acid Nutrition 0.000 claims description 13
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 11
- 229910052791 calcium Inorganic materials 0.000 claims description 11
- 239000011575 calcium Substances 0.000 claims description 11
- RKISUIUJZGSLEV-UHFFFAOYSA-N n-[2-(octadecanoylamino)ethyl]octadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(=O)NCCNC(=O)CCCCCCCCCCCCCCCCC RKISUIUJZGSLEV-UHFFFAOYSA-N 0.000 claims description 11
- 238000006116 polymerization reaction Methods 0.000 claims description 11
- 239000000843 powder Substances 0.000 claims description 11
- SJECZPVISLOESU-UHFFFAOYSA-N 3-trimethoxysilylpropan-1-amine Chemical group CO[Si](OC)(OC)CCCN SJECZPVISLOESU-UHFFFAOYSA-N 0.000 claims description 10
- FWDBOZPQNFPOLF-UHFFFAOYSA-N ethenyl(triethoxy)silane Chemical compound CCO[Si](OCC)(OCC)C=C FWDBOZPQNFPOLF-UHFFFAOYSA-N 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000007664 blowing Methods 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 9
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 claims description 9
- 238000010992 reflux Methods 0.000 claims description 9
- 238000005070 sampling Methods 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 239000003795 chemical substances by application Substances 0.000 abstract description 2
- 239000002994 raw material Substances 0.000 abstract description 2
- 238000004227 thermal cracking Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 14
- 238000009826 distribution Methods 0.000 description 6
- 238000005336 cracking Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000006087 Silane Coupling Agent Substances 0.000 description 4
- 238000004132 cross linking Methods 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229920001169 thermoplastic Polymers 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 1
- 238000005495 investment casting Methods 0.000 description 1
- 238000010667 large scale reaction Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000003110 molding sand Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G8/00—Condensation polymers of aldehydes or ketones with phenols only
- C08G8/28—Chemically modified polycondensates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/20—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents
- B22C1/22—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins
- B22C1/2233—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of organic agents of resins or rosins obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- B22C1/2246—Condensation polymers of aldehydes and ketones
- B22C1/2253—Condensation polymers of aldehydes and ketones with phenols
Abstract
According to the production method of the expanded phenolic resin for precoated sand, the modifier and the modified coupling agent are added, and then the modified phenolic resin is fully mixed with the phenolic resin and other raw materials and interacts with each other, so that the obtained phenolic resin for precoated sand has the advantages of low free phenol content, high softening point, low molecular weight and good fluidity, and thus after the precoated sand is prepared, the obtained precoated sand has high strength, quick curing, less curing agent used in the later period and good high-temperature anti-thermal cracking performance; according to the production method of the expanded phenolic resin for precoated sand, disclosed by the invention, the influence of the modifier component on the free phenol content of the phenolic resin for precoated sand is very small, and the softening point and the fluidity of the phenolic resin for precoated sand are improved after the modifier component is added, so that the phenolic resin is not easy to agglomerate when being prepared into precoated sand, the demolding performance of the precoated sand can be improved, and the phenomenon of shelling of the precoated sand in the use process is prevented.
Description
Technical Field
The invention relates to the technical field of modified phenolic resin, in particular to a production method of expandable phenolic resin for precoated sand.
Background
The precoated sand is molding sand or core sand with a layer of solid resin film covering the surface of gravel before molding, and has good fluidity and stable storage, and the core manufactured by the precoated sand has the advantages of high strength, high dimensional precision, convenient storage and the like, is widely applied to industries such as automobiles, tractors, diesel engines, machine tools, hydraulic parts or pumps and the like at present, and particularly has wide prospects when being used for complex precision castings.
The precoated sand is composed of raw sand and a thermoplastic phenolic resin adhesive, along with the development of a shell method process, on one hand, the requirement on using phenolic resin is higher and higher, the requirement on the high curing speed, the good curing effect and the good high-temperature crack resistance of the phenolic resin is high, and on the other hand, the existing thermoplastic phenolic resin is an exothermic reaction in the reaction process, so that the large-scale reaction is not easy to control, the current production scale is generally small, and the requirement on the using amount of the phenolic resin for the precoated sand in the market cannot be met.
Therefore, the design of the phenolic resin capable of being produced in large scale ensures that the reaction speed of the phenolic resin in the synthesis process is uniform, the production scale of enterprises is obviously enlarged, and the obtained modified phenolic resin product has high curing speed, good curing effect and excellent high-temperature resistance effect, so that the problem to be solved at present is urgently needed.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a production method of the expandable phenolic resin for precoated sand.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a production method of expandable phenolic resin for precoated sand comprises the following steps:
adding phenol and oxalic acid into a reaction kettle, heating to 85-95 ℃ while stirring, dropwise adding formaldehyde, obtaining a reaction solution after dropwise adding, refluxing the reaction solution for 2-4 hours, taking upper-layer water after stopping stirring to detect that the content of free formaldehyde is less than or equal to 0.8%, dehydrating at normal pressure to 155-165 ℃, then dehydrating in vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5%, and keeping for later use;
wherein the mass ratio of phenol to formaldehyde to oxalic acid is 100: 30-45: 10-20;
secondly, adding a modifier into the reaction kettle, cooling to 140-145 ℃, adding organic amine, cooling to 130-135 ℃, and adding a modified coupling agent; heating to 140 ℃, stirring for reaction for 1-2 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 145-150 ℃ and discharging to obtain the phenolic resin for precoated sand;
the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 1-3: 2-4: 10-15: 10-15 parts by weight;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.1-1: 10-15 parts by weight;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 10-15: 0.1-0.5: 0.1 to 0.5;
the mass ratio of the modifier to the organic amine to the modified coupling agent to the phenol in the step I is 0.1-0.5: 0.2-0.4: 0.3-0.6: 100.
preferably, the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 2: 3: 12: 13 of the composition.
Preferably, the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.5: 12.
Preferably, the organosilane coupling agent is aminopropyltrimethoxysilane and/or vinyltriethoxysilane.
Preferably, the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyltriethoxysilane in a mass ratio of 2: 1.
Preferably, the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4.
Preferably, the molecular weight of the polyethylene glycol is 1000-4000.
Further preferably, the polyethylene glycol has a molecular weight of 3000.
Compared with the prior art, the invention has the following advantages:
according to the production method of the expanded phenolic resin for precoated sand, the modifier and the modified coupling agent are added, and then the modified phenolic resin and the phenolic resin are fully mixed and interact with each other, so that the obtained phenolic resin for precoated sand has the advantages of low free phenol content, high softening point, low molecular weight and good fluidity, and thus after the precoated sand is prepared, the obtained precoated sand has the advantages of high strength, quick curing, less curing agent used in the later period and good high-temperature anti-thermal cracking performance.
According to the production method of the expanded phenolic resin for precoated sand, disclosed by the invention, the influence of the modifier component on the free phenol content of the phenolic resin for precoated sand is very small, and the softening point of the phenolic resin for precoated sand is improved and the fluidity of the phenolic resin is improved after the modifier component is added, so that the phenolic resin is not easy to agglomerate when being prepared into precoated sand, the demolding performance of the precoated sand can be improved, and the phenomenon of shelling of the precoated sand in the use process is prevented; in addition, the addition of the modifier component increases the molecular weight of the modifier component, reduces the molecular weight distribution and enables the molecular weight range to be more concentrated;
the addition of the organic amine mainly influences the content of free phenol in the phenolic resin, and along with the increase of the mass ratio of the dimethylaniline to the aniline, the content of the free phenol is increased after being reduced, and the content of the free phenol is increased after the mass ratio of the dimethylaniline to the aniline is 0.5: the content of free phenol reaches the lowest at 12 days;
according to the production method of the expanded phenolic resin for precoated sand, the modified coupling agent can play a good role in dispersing and increasing toughness, and when polyacrylamide and zinc dialkyl dithiophosphate are not available, the modified coupling agent and the silane coupling agent are poor in dispersibility in the phenolic resin and cannot play a good role in crosslinking, so that the numerical value of free phenol is large, the molecular weight is small, the molecular weight distribution is not concentrated, the viscosity is too low, the phenolic resin is easy to flow, and the mechanical strength of the phenolic resin is low.
Detailed Description
The invention aims to provide a production method of expanded phenolic resin for precoated sand, which is realized by the following technical scheme:
a production method of expandable phenolic resin for precoated sand comprises the following steps:
adding phenol and oxalic acid into a reaction kettle, heating to 85-95 ℃ while stirring, dropwise adding formaldehyde, obtaining a reaction solution after dropwise adding, refluxing the reaction solution for 2-4 hours, taking upper-layer water after stopping stirring to detect that the content of free formaldehyde is less than or equal to 0.8%, dehydrating at normal pressure to 155-165 ℃, then dehydrating in vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5%, and keeping for later use;
wherein the mass ratio of phenol to formaldehyde to oxalic acid is 100: 30-45: 10-20;
secondly, adding a modifier into the reaction kettle, cooling to 140-145 ℃, adding organic amine, cooling to 130-135 ℃, and adding a modified coupling agent; heating to 140 ℃, stirring for reaction for 1-2 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 145-150 ℃ and discharging to obtain the phenolic resin for precoated sand;
the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 1-3: 2-4: 10-15: 10-15 parts by weight; the modifier component has little influence on the free phenol content of the precoated sand phenolic resin, and the modifier component is added to improve the softening point and the fluidity of the precoated sand phenolic resin, so that the precoated sand is not easy to agglomerate when prepared, the demolding performance of the precoated sand can be improved, and the shelling phenomenon of the precoated sand in the use process is prevented; in addition, the addition of the modifier component increases the molecular weight of the modifier component, reduces the molecular weight distribution and enables the molecular weight range to be more concentrated;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.1-1: 10-15 parts by weight; the addition of the organic amine mainly influences the content of free phenol in the phenolic resin, and the content of the free phenol is increased after being reduced along with the increase of the mass ratio of the dimethylaniline to the aniline, and the content of the free phenol is increased after being reduced when the further preferable mass ratio of the dimethylaniline to the aniline is 0.5: the free phenol content was minimal at 12 deg.f.
The modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 10-15: 0.1-0.5: 0.1 to 0.5; the polyacrylamide and the zinc dialkyl dithiophosphate play roles in dispersing and increasing toughness in the organosilane coupling agent, and when the polyacrylamide and the zinc dialkyl dithiophosphate are not available, the modifier and the silane coupling agent have poor dispersibility in the phenolic resin and cannot play a good crosslinking role, so that the numerical value of free phenol is larger, the molecular weight is smaller, the molecular weight distribution is not concentrated, the viscosity is too low, the free phenol is easy to flow, and the mechanical strength of the phenolic resin is lower.
The mass ratio of the modifier to the organic amine to the modified coupling agent to the phenol in the step I is 0.1-0.5: 0.2-0.4: 0.3-0.6: 100.
preferably, the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 2: 3: 12: 13 of the composition.
Preferably, the organosilane coupling agent is aminopropyltrimethoxysilane and/or vinyltriethoxysilane.
Preferably, the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyltriethoxysilane in a mass ratio of 2: 1.
Preferably, the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4.
Preferably, the molecular weight of the polyethylene glycol is 1000-4000.
According to the production method, the modifier and the modified coupling agent are added, then the mixture is fully mixed with the phenolic resin and other raw materials and interacts with each other, the content of free phenol in the phenolic resin is reduced by adopting the design of adding organic amine, the capacity of the phenolic resin for precoated sand can be expanded to 3-10 times of the original capacity, for example, a 10-square reaction kettle can be adopted for carrying out the reaction, a 30-100-square reaction kettle can be adopted for carrying out the production, and the production capacity and the production efficiency are greatly improved.
The invention is further described with reference to specific examples.
Example 1
A production method of expandable phenolic resin for precoated sand comprises the following steps:
adding 500kg of phenol and 50kg of oxalic acid into a reaction kettle, heating to 85 ℃ under stirring, dropwise adding 150kg of formaldehyde, obtaining a reaction solution after the dropwise adding is finished, refluxing the reaction solution for 2 hours, taking upper-layer water after the stirring is stopped, dehydrating under normal pressure to 155 ℃ when the content of free formaldehyde is detected to be less than or equal to 0.8%, dehydrating under vacuum, blowing phenol until the mass concentration of the free phenol is less than 2.5%, and keeping for later use;
adding 0.5kg of modifier into the reaction kettle, cooling to 140 ℃, adding 1.0kg of organic amine, cooling to 130 ℃, and adding 1.5kg of modified coupling agent; heating to 140 ℃, stirring for reaction for 1 hour, then sampling, measuring the polymerization rate to 63-67 s, heating to 145 ℃, discharging to obtain phenolic resin for precoated sand;
the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 1: 2: 10: 10;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.1: 15;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 10: 0.1: 0.1.
Example 2
A production method of expandable phenolic resin for precoated sand comprises the following steps:
adding 500kg of phenol and 100kg of oxalic acid into a reaction kettle, heating to 95 ℃ under stirring, dropwise adding 225kg of formaldehyde, refluxing the reaction solution for 4 hours, taking upper water after stirring is stopped, dehydrating under normal pressure to 165 ℃ when the content of free formaldehyde is detected to be less than or equal to 0.8%, dehydrating under vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5% for later use;
wherein the mass ratio of phenol to formaldehyde to oxalic acid is 100: 45: 20;
adding 2.5kg of modifier into the reaction kettle, cooling to 145 ℃, adding 2.0kg of organic amine, cooling to 135 ℃, and adding 3.0kg of modified coupling agent; heating to 140 ℃, stirring for reaction for 2 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 150 ℃, discharging to obtain the phenolic resin for precoated sand;
the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 3: 4: 15: 15; wherein the molecular weight of the polyethylene glycol is 1000;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 1: 10;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 10-15: 0.1-0.5: 0.1 to 0.5; the organosilane coupling agent is vinyltriethoxysilane.
Example 3
A production method of expandable phenolic resin for precoated sand comprises the following steps:
adding 500kg of phenol and 60kg of oxalic acid into a reaction kettle, heating to 90 ℃ under stirring, dropwise adding 175kg of formaldehyde, refluxing the reaction solution for 3 hours, taking upper water after stirring is stopped, detecting that the content of free formaldehyde is less than or equal to 0.8%, dehydrating under normal pressure to 160 ℃, dehydrating in vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5%, and keeping for later use;
adding 1.0kg of modifier into the reaction kettle, cooling to 142 ℃, adding 1.5kg of organic amine, cooling to 132 ℃, and adding 2.0kg of modified coupling agent; heating to 140 ℃, stirring for reaction for 1-2 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 148 ℃, and discharging to obtain the phenolic resin for precoated sand;
wherein the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 2: 3: 14: 12; wherein the molecular weight of the polyethylene glycol is 4000;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.4: 14, the composition is as follows;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.2;
the organosilane coupling agent is aminopropyl trimethoxysilane.
Example 4
A production method of expandable phenolic resin for precoated sand comprises the following steps:
adding 500kg of phenol and 75kg of oxalic acid into a reaction kettle, heating to 90 ℃ under stirring, dropwise adding 200kg of formaldehyde, obtaining a reaction solution after the dropwise adding is finished, refluxing the reaction solution for 3 hours, taking upper-layer water after the stirring is stopped, dehydrating under normal pressure to 160 ℃ when the content of free formaldehyde is detected to be less than or equal to 0.8%, and then dehydrating under vacuum, blowing phenol until the mass concentration of the free phenol is less than 2.5% for later use;
adding 1.5kg of modifier into the reaction kettle, cooling to 141 ℃, adding 1.5kg of organic amine, cooling to 132 ℃, and adding 2.5kg of modified coupling agent; heating to 140 ℃, stirring for reaction for 1.5 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 148 ℃, and discharging to obtain the phenolic resin for precoated sand;
wherein the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 2: 3: 12: 13; wherein the molecular weight of the polyethylene glycol is 3000;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.6: 12;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4; the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyl triethoxysilane according to a mass ratio of 2: 1.
Comparative examples 1 to 4 the preparation methods of examples 1 to 4 were respectively adopted in sequence, and under the condition that other processes were not changed, only the step of adding the modifier was deleted; the phenolic resins for precoated sand obtained in examples 1 to 4 and the phenolic resins for precoated sand obtained in comparative examples 1 to 4 were tested, and the softening point and fluidity were tested by the ball-and-ring method and the inclined plate method, respectively.
The results are shown in Table 1.
TABLE 1 TABLE of Performance test results of the phenol resin for precoated sand obtained in examples 1 to 4 and the phenol resin for precoated sand obtained in comparative examples 1 to 4
As can be seen from the results in table 1, the modifier component of the present invention has little influence on the free phenol content of the precoated sand phenolic resin, and the modifier component is added to improve the softening point and the fluidity of the precoated sand phenolic resin, so that the precoated sand phenolic resin is not easy to agglomerate when prepared into precoated sand, the mold release property of the precoated sand can be improved, and the shelling phenomenon of the precoated sand during use can be prevented.
In addition, the addition of the modifier component increases the molecular weight thereof, reduces the molecular weight distribution, and makes the molecular weight range thereof more concentrated.
The coated sand prepared from the phenolic resin for the coated sand obtained in the examples 1 to 4 and the phenolic resin for the coated sand obtained in the comparative examples 1 to 4 is tested, wherein the coated sand is prepared by the following steps:
heating 150kg of 70-140-mesh Dalin sand to 120-130 ℃, putting the Dalin sand into a precoated sand mixer, adding 3kg of phenolic resin, coating for 60s, then adding 0.30kg of urotropine and 0.60kg of water, mixing for 20s, cooling, crushing, discharging sand, performing performance test, and using a detection instrument: SAT-B type precoated sand electric heating sample preparation machine, SWY type hydraulic strength testing machine, SGQW-1 type precoated sand high-temperature performance tester
The results are shown in Table 2.
Table 2 table of results of performance test of precoated sand
As can be seen from the results in Table 2, the phenolic resin for precoated sand of the invention greatly improves the hot tensile strength and the cold tensile strength and greatly prolongs the high-temperature cracking resistance time due to the addition of the modifier in the preparation process.
The performance of the phenolic resin for precoated sand prepared in example 4 is optimal, so the following comparative examples are all the parameters of example 4 are adjusted, the compositions of organic amine are adjusted under the condition that other parameters are not changed in comparative examples 5 to 7, only the components of the organic silane coupling agent are reserved in comparative example 8 by removing polyacrylamide and zinc dialkyl dithiophosphate in the modified coupling agent, and the results of the test on the phenolic resin for precoated sand obtained in comparative examples 5 to 8 are shown in table 3. The precoated sand was prepared by the same method as described above, and the performance of the precoated sand was measured, and the results are shown in table 4.
TABLE 3 influence of composition of organic amine on the Properties of phenolic resin for precoated Sand
As can be seen from table 3, as the mass ratio of dimethylaniline to aniline increases, the molecular weight of the phenol resin for precoated sand gradually decreases, the fluidity gradually increases, the softening point slightly increases, and the content of free phenol decreases and increases.
The polyacrylamide and the zinc dialkyl dithiophosphate play roles in dispersing and increasing toughness in the organosilane coupling agent, and when the polyacrylamide and the zinc dialkyl dithiophosphate are not available, the modifier and the silane coupling agent have poor dispersibility in the phenolic resin and cannot play a good crosslinking role, so that the numerical value of free phenol is larger, the molecular weight is smaller, the molecular weight distribution is not concentrated, the flowability is good, and the mechanical strength of the phenolic resin is lower.
Table 4 table of performance test results of precoated sand
As can be seen from the data in table 4, the mass ratio of dimethylaniline and aniline has a smaller effect on the hot tensile strength and the cold tensile strength, and has a larger effect on the high-temperature cracking resistance time at 1000 ℃, and as the mass ratio of dimethylaniline and aniline increases, the high-temperature cracking resistance time at 1000 ℃ increases and then decreases, and the ratio is 0.6: 12, the maximum value is reached because the proper increase of the dimethylaniline content in the organic amine increases the degree of crosslinking in the phenolic resin, thereby increasing the strength after curing and improving the heat cracking resistance, but the amount of dimethylaniline is not preferably too high.
The addition of polyacrylamide and zinc dialkyl dithiophosphate can improve the mechanical strength of the coated sand, such as the hot tensile strength and the cold tensile strength of the coated sand, and prolong the high-temperature cracking resistance time of 1000 ℃.
Comparative example 9
A production method of phenolic resin for precoated sand comprises the following steps:
adding 50kg of phenol and 7.5kg of oxalic acid into a reaction kettle, heating to 90 ℃ under stirring, dropwise adding 20kg of formaldehyde, refluxing the reaction solution for 3 hours, taking upper water after stirring is stopped, detecting that the content of free formaldehyde is less than or equal to 0.8%, dehydrating under normal pressure to 160 ℃, dehydrating under vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5% for later use;
② adding 0.15kg of organic amine into the reaction kettle, cooling to 132 ℃, and adding 0.25kg of modified coupling agent; heating to 140 ℃, stirring for reaction for 4 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 148 ℃, and discharging to obtain the phenolic resin for precoated sand;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.6: 12;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4; the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyl triethoxysilane according to a mass ratio of 2: 1.
Comparative example 10
A production method of phenolic resin for precoated sand comprises the following steps:
adding 500kg of phenol and 75kg of oxalic acid into a reaction kettle, heating to 90 ℃ under stirring, dropwise adding 200kg of formaldehyde, obtaining a reaction solution after the dropwise adding is finished, refluxing the reaction solution for 3 hours, taking upper-layer water after the stirring is stopped, dehydrating under normal pressure to 160 ℃ when the content of free formaldehyde is detected to be less than or equal to 0.8%, and then dehydrating under vacuum, blowing phenol until the mass concentration of the free phenol is less than 2.5% for later use;
② adding 1.5kg of organic amine into the reaction kettle, cooling to 132 ℃, and adding 2.5kg of modified coupling agent; heating to 140 ℃, stirring and reacting for 4 hours, and then sampling and measuring the polymerization rate which can not reach 63-67 s all the time and is more than 100 s;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.6: 12;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4; the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyl triethoxysilane according to a mass ratio of 2: 1.
As can be seen from comparative example 9 and comparative example 10, the polymerization rate can be barely required after stirring reaction for 4 hours in comparative example 9 due to the small amount of the added substances, while the polymerization rate can not be always required after 10 times of production expansion in comparative example 10, and it can be seen that the modifier (the composition of ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol) of the invention has very important significance for expanding the productivity.
Claims (8)
1. A production method of expandable phenolic resin for precoated sand is characterized by comprising the following steps: the method comprises the following steps:
adding phenol and oxalic acid into a reaction kettle, heating to 85-95 ℃ while stirring, dropwise adding formaldehyde, obtaining a reaction solution after dropwise adding, refluxing the reaction solution for 2-4 hours, taking upper-layer water after stopping stirring to detect that the content of free formaldehyde is less than or equal to 0.8%, dehydrating at normal pressure to 155-165 ℃, then dehydrating in vacuum, blowing phenol until the mass concentration of free phenol is less than 2.5%, and keeping for later use;
wherein the mass ratio of phenol to formaldehyde to oxalic acid is 100: 30-45: 10-20;
secondly, adding a modifier into the reaction kettle, cooling to 140-145 ℃, adding organic amine, cooling to 130-135 ℃, and adding a modified coupling agent; heating to 140 ℃, stirring for reaction for 1-2 hours, then sampling, measuring the polymerization rate to 63-67 s, heating to 145-150 ℃ and discharging to obtain the phenolic resin for precoated sand;
the modifier is prepared from ethylene bis stearamide, calcium powder, activated carbon and polyethylene glycol according to a mass ratio of 1-3: 2-4: 10-15: 10-15 parts by weight;
the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.1-1: 10-15 parts by weight;
the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 10-15: 0.1-0.5: 0.1 to 0.5;
the mass ratio of the modifier to the organic amine to the modified coupling agent to the phenol in the step I is 0.1-0.5: 0.2-0.4: 0.3-0.6: 100.
2. the method for producing an expandable phenol resin for precoated sand according to claim 1, wherein: the modifier is prepared from ethylene bis stearamide, calcium powder, active carbon and polyethylene glycol according to a mass ratio of 2: 3: 12: 13 of the composition.
3. The method for producing an expandable phenol resin for precoated sand according to claim 1, wherein: the organic amine is prepared from dimethylaniline and aniline according to a mass ratio of 0.5: 12.
4. The method for producing an expandable phenol resin for precoated sand according to claim 1, wherein: the organosilane coupling agent is aminopropyltrimethoxysilane and/or vinyl triethoxysilane.
5. The method for producing an expandable phenol resin for precoated sand according to claim 4, wherein: the organosilane coupling agent is prepared from aminopropyltrimethoxysilane and vinyl triethoxysilane according to a mass ratio of 2: 1.
6. The method for producing an expandable phenol resin for precoated sand according to claim 4, wherein: the modified coupling agent is an organosilane coupling agent, polyacrylamide and zinc dialkyl dithiophosphate according to the mass ratio of 12: 0.4: 0.4.
7. The method for producing an expandable phenol resin for precoated sand according to claim 1, wherein: the molecular weight of the polyethylene glycol is 1000-4000.
8. The method for producing an expandable phenol resin for precoated sand according to claim 7, wherein: the molecular weight of polyethylene glycol is 3000.
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| CN117487105B (en) * | 2024-01-02 | 2024-03-26 | 山东宇世巨化工有限公司 | Preparation method of phenolic resin for precoated sand |
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