A kind of nanoscale cast moulding (core) sand binding agent and its production and use
Technical field
The present invention relates to molding sand adhesive for casting, specifically, is a kind of casting self-hardening property type (core) sand binding agent and its production and use.Casting binder of the present invention is except the making that can be used for common casting sand mold (core), be particularly useful for type (core) sand is had large-scale, the intricate casting of specific (special) requirements, for example large nuclear-power equipment, hydrogenation reactor, the cylinder block, heavy (merchant) mill memorial archway etc. of generating set and gas turbine more than 200,000 kilowatts.
Background technology
In recent years, thermosetting phenolic resin, liquid alkalescent phenol resin that particularly make with base catalyst, in the presence of strongly basic medium has obtained more application as type (core) sandbinder at foundry industry, develops very fast.But existing product remains in some shortcomings: the one, and the tensile strength of the alkalescent phenol resin that these binding agents are used is too low, (as below 10 ℃) sand mold (core) of making particularly at low temperatures, intensity can not meet the needs of production; The 2nd, after the resin sand of preparation is placed the long period, as more than 100 minutes, it is a lot of to be descended by sand mold (core) intensity of these resins system of mixing, as with commercially available ester solidified liquid alkalescent phenol resin, its intensity only is about 0.40Mpa, can not satisfy the production needs after 100 minutes; The 3rd, the poor stability of resin, the storage period of guaranteeing the quality is no longer than three months, through actual measurement, deposit one month under 25 ℃ after, initial performance promptly descends more than 30%; The 4th, bad in sand mold (core) surface stability that make summer, defectives such as sand washing when easily causing the foundry goods casting, inner burning into sand, MT, UT carrying out flaw detection qualification rate are low.Analyze the reason of the problems referred to above, the consistent view of current science and industrial circle is:
The alkalescent phenol resin of---used, active low, viscosity is big, when making sand mold (core), sand mobile bad, the inhomogeneous densification of sand mold (core) internal structure causes its overall performance low; And the reclamation rate of sand is low.
---unreasonable with the curing agent molecular structure of these resin completes, solidification rate is too fast, surveys hardening time (tensile strength of sand mold descended 20% o'clock) less than 80 minutes (25 ℃); The resin sand resting period of preparation is short, and when making large-scale, complicated sand mold (core), required time is very long, causes the inner easily layering of sand mold (core), can't form firm integral body, and intensity is low.
For above-mentioned reasons, no matter existing casting sand binding agent is from product, still from using the needs that all can not satisfy heavy castings, for example large nuclear-power equipment, hydrogenation reactor, the cylinder block, heavy (merchant) mill memorial archway etc. of generating set and gas turbine more than 200,000 kilowatts, the molten steel casting temperature of these foundry goods up to more than 1500 ℃, weight reaches 700 tons, change in size is big, wall thickness is from 10mm to 〉=1000mm, requires very high to quality index such as the intensity of service time of resin sand, sand mold (core), stability.
In addition, composition harmful in the existing alkalescent phenol resin is too high: for example the content of free formaldehyde, free-phenol is respectively 0.10%-3.5%, 0.20%-5%, make the scene give out the strong impulse peculiar smell in making sand mold, core and the demoulding, mould assembling, baking, casting cycle, bad reactions such as eyes are shed tears, throat is sore, dizzy, nauseating appear in the operator.
Except that these problems that above-mentioned commercial goods exists, the resin of introducing according to Chinese patents such as application publication number CN1385264A, when adopting the curing agent of its recommendation to make big sand mold (core) at a lower temperature, its intensity, smell, up time also are the ten minutes distinct issues, elements harmful such as nitrogenous, the phosphorus of the curing agent that adopts of the open text of these patent applications, sulphur particularly to foundry goods, as hexamethylenetetramine or p-methyl benzenesulfonic acid class etc., the inherent quality of foundry goods is not high; The Chinese patent of application publication number CN1392196A and for example, employed with the existing techniques in realizing intercalation is phenolic resins 2123,2124 etc., the employed curing agent of these resins still is aforesaid hexamethylenetetramine class simultaneously, casting resin sand with these resins, mobile bad, the quality of sand mold (core) is not so good, and intensity is low, the gas forming amount height, the up time lacks, especially should not make large-scale, complicated sand mold (core).
Summary of the invention
The objective of the invention is to overcome above-mentioned the deficiencies in the prior art part, a kind of cast moulding (core) sandbinder is provided, the phenol resin active height of binding agent, clay flake are peeled off by intercalation in phenolic resins and are the nanoscale dispersion; The binding agent stable performance has no adverse effects to foundry goods, on-the-spot free from extraneous odour.
Another object of the present invention provides a kind of preparation method of above-mentioned binding agent, and processing step is simple and direct, uses conventional equipment, and it is less to produce molecular weight, and the higher high activity phenolic resins of methylol group content.
Using method when a purpose again of invention provides a kind of above-mentioned binding agent and is used to make casting sand (core) is made casting sand type (core) with the method, high efficiency, and the intensity height of sand mold (core), gas forming amount≤7ml/g, the quality of foundry goods is good; Resin sand resting period 〉=190 minute, sand reclamation rate 〉=90; The needs of making large-scale, complicated sand mold (core) can be satisfied, economic benefit of enterprises can be increased substantially.
Realize the key of above-mentioned purpose: the one, the activity of raising phenolic resins, the activity of resin is high more, and the decentralization of clay flake in resin is good more, and the intensity of the casting resin sand of preparation is high more; The 2nd, want big with the solidification rate adjusting range of the curing agent of phenolic resins adapted.
As everyone knows, under the base catalyst effect, formaldehyde and phenol pass through-CH
2-group progressively polymerization links up, and its reaction mechanism it is generally acknowledged that phenol and formaldehyde at first react and form adjacent or to hydroxymethylphenol, hydroxymethylphenol with another phenol molecular reaction, loses a part water then, generates by-CH
2-the compound that contains two phenyl ring that is tied when this process continues again, just obtains macromolecular compound; Because three positions that are subject to attack are arranged, on each phenol molecule so end product contains many cross-bonds.This phase I both can be regarded as the electrophilic substitution reaction of the positive carbon atom of formaldehyde to phenyl ring, also can be regarded as the nucleophilic addition of aromatic rings to carbonyl.Alkali is by phenol being become the benzene negative oxygen ion of more active (cloud density is bigger) to the catalysis of reaction.Condensation reaction under the acid condition is protonated formaldehyde, thereby has increased the electropositive of carbonylic carbon atom.Addition generates hydroxymethylphenol, hydroxymethylphenol generation polycondensation then, and dehydration generates resol.According to surveying and determination, the speed of the speed ratio polymerisation of addition reaction is much bigger, so final reaction thing majority is a linear structure, is three-dimensional-structure on a small quantity.The methylol group content of resol and molecular structure, closely related with synthesis condition.Can obtain the resol of various different performances by the control synthesis condition.Have high activity methylol (or being called the Bian hydroxyl) in the alkalescent phenol resin that ester solidifies, under the effect of ester, form methylene bridge and commissure curing.From resin itself, the molecular weight size of what and resin of the methylol group content in the resin is the key that influences the binding agent adhesion strength, and within the specific limits, the molecular weight of resin is more little, and methylol group content is many more, and activity is also high more, and adhesion strength is big more.Yet, since polymerisation itself, the excessive resin of molecular weight that is easy to get very much, and the content of its methylol is very low.Therefore, have only and select reasonably prescription and synthesis technique, just can make the binding agent of excellent performance.Technological means of the present invention is: when the preparation resol, reaction quantitatively causes the alkali metal acetate that uses activated processing to phenol formaldehyde condensation, form more active reaction point, add potassium hydroxide catalysed then, the further polycondensation of phenolic aldehyde, form activated group, less through back operation acquisition molecular weight again, and the more high activity thermosetting attitude phenolic resins of methylol group content; Utilize simultaneously in the phenolic aldehyde polycondensation process the intercalation effect of clay, obtain nano level phenolic aldehyde/clay product; In addition, when preparing casting resin sand, adopt the complex ester curing agent with this phenolic resins.The above is the principal character that is different from prior art, is inventive point of the present invention.
Concrete technical solution of the present invention is as follows:
Cast moulding of the present invention (core) sand binding agent, mixture ratio by weight percent is: phenol 16--30%, aldehyde 40--55%, clay 0.5--10%, base catalyst 15--30%, silane coupler 0.01--2%, alkali metal acetate 0.5--10%.Preferred proportioning is: phenol 21--25%, aldehyde 49--52%, clay 0.5--3%, base catalyst 20--25%, silane coupler 0.01--0.3%, alkali metal acetate 0.8--3% (being more preferred from 0.8--1%).
Described phenol is phenol, to (or) cresols, (or to) benzenediol, bis-phenol--A, bis-phenol--F phenolic compound one or more mixture wherein, preferably phenol.
Described aldehyde is formaldehyde, paraformaldehyde, glyoxal, acetal, furtural wherein one or more mixture, preferably formaldehyde.
Described base catalyst is an alkali metal hydroxide, can be wherein one or more mixture, preferably potassium hydroxide.
Described clay is a layer silicate mineral, comprise content at the montmorillonite more than 80%, bentonite, hectorite, tiredly take off stone, vermiculite, granularity is narrower than 200 orders, is preferably to be narrower than 350 orders, specific area 700-800m
2/ g, interlayer has Na
+, Ca
2+, Mg
2+Deng exchangeable cations, ion-exchange total capacity (CEC) is 50-200meq/100g, and clay layer thickness is 0.8-2.1nm for the 0.9-1.1nm interfloor distance.
Cast moulding of the present invention (core) the sand preparation method of binding agent, be that phenol, aldehyde, clay, base catalyst, silane coupler, the temperature-gradient method of alkali metal acetate material, the reinforced synthesis technique of segmentation of aforementioned proportion are produced target product, promptly in the phenol alkaline aqueous solution, progressively add aldehyde liquid, the phenolic aldehyde condensation temperature is controlled at that multistage carries out within 55-110 ℃, reaction time is 0.5-24 hour, and the methylol group content of product 〉=15%, viscosity are 40-160cts (25 ℃).Preferred reaction temperature is 65-95 ℃, reaction time 2-10 hour.
Described preparation method, concrete steps are as follows:
(1) phenol is placed reactor, stir, heat up, when temperature is 55 ℃ ± 2 ℃, add solid-state alkali metal acetate through activation processing, reaction causes to phenol formaldehyde condensation, form the active reaction point of a greater number, it is controlled at the molecular weight of resin for subsequent handling in the scope of requirement and creates precondition;
(2) be warming up to 65 ℃ ± 2 ℃, add the base catalyst of base catalyst total amount 1/3, progressively splash into formaldehyde simultaneously, this section period was controlled at 0.5-1.5 hour;
(3) add clay then, add the base catalyst of base catalyst total amount 1/3 again, continue to heat up, 75 ℃ ± 5 ℃ reactions of temperature 1.5-6 hour;
(4) be warming up to 100 ℃ ± 5 ℃, react after 1.5-4 hour, the base catalyst that adds base catalyst total amount 1/3 again, adding silicon when question response thing viscosity reaches 50-75 (centipoise/25 ℃) is coupling agent, cool below 45 ℃, liquid alkali phenolic resin adhesive, this resin is less and the resol that methylol group content is more of molecular weight.
Described clay is not limited to add in step (3), can also add in step (1) or step (2).
Binding agent of the present invention is used to prepare the method for casting resin sand, gets 100 parts of sand grains, alkali phenolic resins 1.5-2.5 part, complex ester curing agent 0.2-0.8 part by weight, adds the complex ester curing agent earlier and mix in sand, adds alkali phenolic resins again and mixes.Resulting resin sand up time 〉=190 minute; Sand reclamation rate 〉=90.
Described complex ester curing agent is:
1. organic epoxide, comprise the monobasic of carbon number 2-20 or the glycidol ether of multi-hydroxy compound and derivative thereof, and the ether that contracts of epoxy adduct and multi-hydroxy (as the minashi sugar alcohol polyglycidyl ether), these organic epoxides must have the solubility more than 20% in water; And/or
2. organic ester such as γ---butyrolactone, glycerine acetate, glycol acetate etc., the organic ester that the monocarboxylic acid of the monobasic of these carbon numbers 1-10 or polyalcohol and carbon number 1-10 forms, can contain one or more organic epoxide and organic esters in the curing agent, the consumption of these mixed curing agents is 15%-30% of alkali phenolic resins; And/or
3. feed carbon dioxide and solidify molding sand, the core sand of the system of mixing with alkali phenolic resins; And/or
4. preferred 1. above-mentioned and 2. in the complex ester formed of multiple compound.
Described sand grains is quartz sand, chrome ore, 70 sand, magnesia, zircon sand, emergy or their mixture.
Useful good effect of the present invention:
1. because when the preparation resol, reaction quantitatively causes the alkali metal acetate that uses activated processing to phenol formaldehyde condensation, form more active reaction point, obtain molecular weight 400-600, and the high activity thermosetting attitude phenolic resins of methylol group content 〉=15%, resin flow is good, and clay reaches nanoscale in phenolic resins disperses, with sand mold (core) the internal structure even compact that this resin is made, intensity height.
2. owing to adopt the complex ester curing agent, solidification rate is low, resin sand up time 〉=190 of preparation minute, and when making large-scale, complicated sand mold (core), can aliquation, good integrity, intensity height.
3. because the active height of resin, clay reaches exfoliated nanoscale in phenolic resins disperses, each component of resin sand of preparation mixes, sand mold (core) heat resistance of making is good, and sand mold (core) surface quality is good, and deformability is good, and gas forming amount is low, do not have defectives such as sand washing, inner burning into sand, crackle when refractoriness height, foundry goods casting, the quality of foundry goods is good; Sand reclamation rate 〉=90.
4. because clay reaches exfoliated nanoscale dispersion in phenolic resins, each component of resin sand of preparation mixes, harmful composition such as the aldehyde in the resin, phenol is by fully attached to clay and sand grain surface, seldom be in free state, not volatile, spill in the air, so the job site free from extraneous odour, favourable workers ' health.
The specific embodiment
The present invention is further described below in conjunction with embodiment, but the invention is not restricted to these specific embodiments.
Embodiment one
In the three-necked bottle of 3000ml, add mixed phenol liquid (phenol: cresols=13: 1, under the weight ratio with) 490 grams, open electric mixer, be to add active acetate potassium 20 grams at 55 ℃ ± 2 o'clock in temperature; When temperature rises to 63 ℃, add first potassium hydroxide (50%, same under the concentration) 150 grams, drip formaldehyde (37%, same under the concentration) 850 grams simultaneously, the joining day is controlled at and is no less than 30 minutes; Add sodium bentonite 65 grams, second batch of follow-up temperature of continuing rising of potassium hydroxide (50%) 150 gram then, reacted 2.5 hours down at 75-80 ℃; Add the 3rd batch of potassium hydroxide (50%) 150 gram again, be warming up to 95 ℃ of reactions 1 hour, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, up to reaching 50-55 (centipoise/25 ℃), is cooled to below 40 ℃, add 10 gram silane couplers and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts of Da Lin normal sands (40-70 order), 2 parts in alkali phenolic resins, 0.55 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in sand, adding alkali phenolic resins again mixed 1.5 minutes, be made into calibrated bolck then and measure its parameter, the result is as follows:
Temperature (℃) 20 15 10 85
Tensile strength (Mpa/24 hour) 1.54 1.50 1.41 1.38 1.25
Up time (minute) 120 130 150 180 180
Embodiment two
Adding phenol 600 grams in the three-necked bottle of 3000ml, open electric mixer, is that 55 ℃ ± 2 o'clock adding active acetate potassium 20 grams, sodium bentonites 70 restrain in temperature; Add first potassium hydroxide (50%) 150 gram when temperature rises to 63 ℃, drip formaldehyde (37%) 1000 gram simultaneously, the joining day is controlled at and is no less than 30 minutes; The follow-up temperature of continuing rising of second batch of potassium hydroxide (50%) 150 gram to be added was reacted 2.5 hours down at 75-80 ℃; Add the 3rd batch of potassium hydroxide (50%) 150 gram again, be warming up to 95 ℃ of reactions 1 hour, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, reaches 50-55 (centipoise/25 ℃) up to viscosity, is cooled to below 45 ℃, add 13 gram silane couplers and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts of Da Lin normal sands (40-70 order), 1.8 parts in alkali phenolic resins, 0.50 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in sand, adding alkali phenolic resins again mixed 1.5 minutes, be made into calibrated bolck then and measure its parameter, the result is as follows:
Temperature (℃) 20 15 10 85
Tensile strength (Mpa/24 hour) 1.49 1.46 1.40 1.32 1.05
Up time (minute) 120 130 150 180 210
Embodiment three
(phenol: cresols=13: 1) 480 restraining, open electric mixer, is 55 ℃ ± 2 o'clock adding active acetate potassium 20 grams in temperature to add mixed phenol liquid in the three-necked bottle of 3000ml; Continuing to heat up adds first potassium hydroxide (50%) 150 gram, when temperature rises to 63 ℃, begins to drip paraformaldehyde (37%) 850 gram, and the joining day is controlled at and is no less than 30 minutes; Add calcium-base bentonite 65 grams, second batch of follow-up temperature of continuing rising of potassium hydroxide (50%) 150 gram then, reacted 2 hours down at 75-80 ℃; Add the 3rd batch of potassium hydroxide (50%) 150 gram again, be warming up to 95 ℃ of reactions 1 hour, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, reaches 50-55 (centipoise/25 ℃) up to viscosity, is cooled to below 40 ℃, add 12 gram silane couplers and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts of Da Lin normal sands (40-70 order), 2 parts in alkali phenolic resins, 0.6 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in sand, adding alkali phenolic resins again mixed 1.5 minutes, be made into calibrated bolck then and measure its parameter, the result is as follows:
Temperature (℃) 20 15 10 85
Tensile strength (Mpa/24 hour) 1.20 1.19 1.07 1.00 0.91
Up time (minute) 120 130 150 180 180
Embodiment four
(phenol: bisphenol-A=10: 0.7) 660 restraining, open electric mixer, is 55 ℃ ± 2 o'clock adding active acetate potassium 50 grams in temperature to add mixed phenol liquid in the three-necked bottle of 3000ml; Continuing to heat up adds first potassium hydroxide (50%) 100 gram, when temperature rises to 65 ℃, begins to drip formaldehyde (37%) 1100 gram, and the joining day is controlled at and is no less than 30 minutes; Add sodium bentonite 75 grams, second batch of follow-up temperature of continuing rising of potassium hydroxide (50%) 100 gram then, reacted 2.5 hours down at 75-80 ℃; Add the 3rd batch of potassium hydroxide and NaOH equal proportion mixture (50%) 100 gram again, be warming up to 95 ℃ of reactions 1 hour, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, up to reaching 50-55 (centipoise/25 ℃), is cooled to below 40 ℃, add 15 gram silane couplers and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts of Da Lin normal sands (40-70 order), 1.8 parts in alkali phenolic resins, 0.45 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in sand, adding alkali phenolic resins again mixed 1.5 minutes, be made into calibrated bolck then and measure its parameter, the result is as follows:
Temperature (℃) 20 15 10 85
Tensile strength (Mpa/24 hour) 1.50 1.42 1.29 1.23 1.00
Up time (minute) 120 130 150 180 180
Embodiment five
Adding phenol liquid 320 grams in the three-necked bottle of 3000ml, open electric mixer, is 55 ℃ ± 2 o'clock adding active acetate potassium 60 grams in temperature; When temperature rises to 65 ℃ of left and right sides, add first potassium hydroxide (50%) 100 gram, begin to drip formaldehyde (37%) 1040 gram simultaneously, the joining day is controlled at and is no less than 30 minutes; Add sodium bentonite 160 grams, second batch of follow-up temperature of continuing rising of potassium hydroxide (50%) 100 gram then, reacted 5 hours down at 75-80 ℃; Add the 3rd batch of potassium hydroxide (50%) 100 gram again, be warming up to 95 ℃ of reactions 3 hours, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, up to reaching 50-55 (centipoise/25 ℃), is cooled to below 40 ℃, add 20 gram silane couplers and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts of Da Lin normal sands (40-70 order), 2 parts in alkali phenolic resins, 0.55 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in sand, adding alkali phenolic resins again mixed 1.5 minutes, be made into calibrated bolck then and measure its parameter, the result is as follows:
Temperature (℃) 20 15 10 85
Tensile strength (Mpa/24 hour) 1.03 0.92 0.90 0.88 0.82
Up time (minute) 120 130 150 180 180
Embodiment six
(phenol: cresols=13: 1) 110 kilograms, open electric mixer is to add 8 kilograms in active acetate potassium at 55 ℃ ± 2 o'clock in temperature to add mixed phenol liquid in 1 cubic metre reactor; When temperature rises to 65 ℃, add (50%) 37.5 kilogram in first potassium hydroxide, slowly add (37%) 240 kilogram in formaldehyde simultaneously, the joining day is controlled at and is no less than 30 minutes; Add 10 kilograms of sodium bentonites, (50%) 37.5 kilogram of follow-up temperature of continuing rising of second batch of potassium hydroxide then, reacted 2.5 hours down at 75-80 ℃; Add (50%) 37.5 kilogram in the 3rd batch of potassium hydroxide again, be warming up to 95 ℃ of reactions 1 hour, temperature is controlled within 100-105 ℃ therebetween, use the rotary viscosity design determining system viscosity then, per 10 minutes once, reaches 55-60 (centipoise/25 ℃) up to viscosity, is cooled to below 45 ℃, add 0.7 kilogram of silane coupler and stirred 30 minutes, promptly get alkali phenolic resins.
Prepare resin sand with above-mentioned synthetic liquid alkali phenolic resins in following ratio (weight ratio): 100 parts in Xifeng, Fujian sand (40-70 order), 2.5 parts in alkali phenolic resins, 0.75 part in complex ester curing agent, the process for preparation of resin sand mixed 1 minute at first add the complex ester curing agent in puddle mixer, adding alkali phenolic resins again mixed 1.5 minutes, make weigh 42 tons turbine blade sand mold of molten steel with it then, as follows to the index of correlation testing result at resin and moulding scene:
Aldehyde dissociates in the free phenol air in the free aldehyde air in the free phenol resin in the resin
0.08% 0.05% ≤0.06ppm ≤0.01ppm
Smoke-density (mg/m
3) resin sand gas forming amount (ml/g) resin sand reclamation rate (%)
0.12 5.2 95
Bright and clean, the profile tolerance≤0.5-1mm of gained cast(ing) surface, size is accurate, reaches the quality requirement of regulation fully through the flaw detection product, thus high-temperature behavior, collapsibility of having proved the resin sand that makes with the present invention etc. are all very good.
Silane coupler in the foregoing description can be KH550, KH560 etc.
Binding agent of the present invention has multiple use, also can be used as the modifier of the binding agent of laminate, emery wheel and coating, plastics, fiber.