A kind of modified melamine high-efficiency water reducing agent with low cost
Technical field:
The invention belongs to additive for building material and chemosynthesis technical field, be specifically related to a kind of modified melamine high-efficiency water reducing agent with low cost and preparation method thereof.
Background technology:
The production of modern concrete, application be unable to do without concrete admixture, and admixture has become the 5th kind of integral part except cement, water, sand, stone in the concrete.Water reducer is that application surface is the widest in the admixture, also maximum a kind of of usage quantity, and its consumption accounts for more than 80% of the total consumption of admixture.High efficiency water reducing agent is a kind of water-reducing rate height, neither the also water reducer of not bleed of slow setting.Because the appearance of high efficiency water reducing agent just makes high strength, high flowability concrete be achieved, and has guaranteed the development of concrete construction novel process.High efficiency water reducing agent commonly used at present has naphthalene water reducer, thionamic acid salt water reducer, aliphatics based water reducer, melamine class water reducer and poly carboxylic acid series water reducer etc.
Compare with general cement water reducing agent, the trimeric cyanamide series high-efficiency water-reducing agent can significantly improve concrete intensity and weather resistance; No bleed can not form a large amount of bubbles at inside concrete: have excellent adaptability and other kind admixture consistency good to the fine aluminium acid salt cement, can use or be re-dubbed multi-functional compound additive together and use; Steam curing process adaptability is better than other type high efficiency water reducing agent; The main ingredient that can be used as water-proof material is used, and in polychromy concrete, heat resistant fire-proof concrete, oil well reinforced concrete and some special engineerings good application prospects is arranged.But there is the production cost height in such water reducer, is difficult to make pulvis, stock and trucking costs height, and shortcomings such as reaction is harsh strict, difficult quality control.These mass production and marketing that influenced it are greatly used.Number of patent application is that 200310115062.9 disclosed modified melamine high-efficiency water-reducing agents are that melamine high-efficiency water-reducing agent is in the past carried out modification, delay concrete time of coagulation, solve concrete big problem of slump-loss in transportation, construction process, but its cost is higher.
Summary of the invention:
The present invention has done many exploration work on reducing cost, when keeping trimeric cyanamide series high-efficiency water-reducing agent premium properties, trimeric cyanamide monomer with comparatively cheap reactive monomer urea instead of part costliness has synthesized the comparatively cheap trimeric cyanamide series high-efficiency water-reducing agent of cost.
For achieving the above object, the present invention is by the following technical solutions:
Modified melamine high-efficiency water reducing agent with low cost of the present invention, it is characterized in that: it is a main raw material with urea, trimeric cyanamide, formaldehyde, sodium bisulfite, Sodium Pyrosulfite, be aided with sodium hydroxide and sulfuric acid as the pH regulator agent, under 50~95 ℃ temperature condition, through four reactions steps such as 4~8 hours methylolations, sulfonation, condensation reaction, alkalescence reformations, generate faint yellow transparent melamine high-efficiency water-reducing agent.
Above-mentioned low-cost modified melamine water reducing agent is characterized in that: each components contents (weight) per-cent is: trimeric cyanamide 4~20%, urea 4~20%, sodium bisulfite 5~10%, formaldehyde 2~30%, Sodium Pyrosulfite 5~10%, sodium hydroxide 0.05%~5%, sulfuric acid 0.05~5%, water 10~70%.
Melamine high-efficiency water-reducing agent of the present invention, each process condition is as follows:
The step 1 methylolation stage
(1) mol ratio of reactant is:
Trimeric cyanamide: urea: formaldehyde=(0.2~0.8): (0.2~1): (1.5~6);
(2) temperature of reaction: 70~85 ℃;
(3) reaction times: 50~60min;
(4) pH value: between 8~10.
The step 2 sulfonation reaction stage
(1) mol ratio of reactant is:
Sodium bisulfite: Sodium Pyrosulfite: trimeric cyanamide: urea
=(0.5~1.5)∶(0.5~1)∶(0.5~1)∶(0.5~1);
(2) temperature of reaction: 80~90 ℃;
(3) reaction times: 100~120min;
(4) pH value: between 10~12.
The step 3 condensation reaction stage
(1) temperature of reaction: 50~60 ℃;
(2) reaction times: 100~140min;
(3) pH value: between 4.5~6.
The alkaline reformation stage of step 4
(1) temperature of reaction: 85~95 ℃;
(2) reaction times: 60~90min;
(3) pH value: between 8.5~10.5.
Compared with prior art, the present invention has following advantage:
(1) water-reducing rate height, stable performance, volume is lower, does not have obvious bleed and slow setting, good fluidity in practical engineering application, time of coagulation is short.
(2) cost is lower, utilizes rational modification scheme and suitable replacement amount, under the situation that keeps the water reducer use properties, successfully uses the expensive trimeric cyanamide monomer of urea instead of part, reduces production costs significantly.
(3) effect is better than other kind water reducer in steam-curing concrete, under the situation that does not change concrete mix, adds water reducer of the present invention, can make steam-cured back intensity improve 35~40%, shortens 1.5~2.5 hours steam-cured time.
Embodiment:
Embodiment 1 (proportioning is a mol ratio)
In four-hole boiling flask, add 0.4 part of trimeric cyanamide, 0.2 part of urea and 1.5 parts of formaldehyde (37% aqueous solution), stir, regulate pH=8, heat to 70 ℃, reacted 50 minutes; Drop into 0.4 part of sodium bisulfite, 0.2 part of Sodium Pyrosulfite and a part of deionized water, regulate pH=10, heat temperature raising to 80 ℃ reacted 100 minutes; Cool to 50 ℃, regulate pH=4.5, reacted 100 minutes; Be warming up to 85 ℃, regulate pH=8.5, reaction 60min.Reduce to normal temperature, both got melamine high-efficiency water-reducing agent of the present invention.
Embodiment 2 (proportioning is a mol ratio)
In four-hole boiling flask, add 0.3 part of (mole number) trimeric cyanamide, 0.3 part of urea and 1.8 parts of formaldehyde (37% aqueous solution), stir, regulate pH=8.5, heat to 70 ℃, reacted 50 minutes; Drop into 0.4 part of sodium bisulfite, 0.3 part of Sodium Pyrosulfite and a part of deionized water, regulate pH=10, heat temperature raising to 80 ℃ reacted 100 minutes; Cool to 50 ℃, regulate pH=4.5, reacted 100 minutes; Be warming up to 85 ℃, regulate pH=8.5, reaction 60min.Reduce to normal temperature, both got melamine high-efficiency water-reducing agent of the present invention.
Embodiment 3 (proportioning is a mol ratio)
In four-hole boiling flask, add 0.3 part of trimeric cyanamide, 0.4 part of urea and 2.0 parts of formaldehyde (37% aqueous solution), stir, regulate pH=8.5, heat to 80 ℃, reacted 60 minutes; Drop into 0.4 part of sodium bisulfite, 0.3 part of Sodium Pyrosulfite and a part of deionized water, regulate pH=10, heat temperature raising to 85 ℃ reacted 100 minutes; Cool to 50 ℃, regulate pH=4.5, reacted 100 minutes; Be warming up to 85 ℃, regulate pH=8.5, reaction 60min.Reduce to normal temperature, both got melamine high-efficiency water-reducing agent of the present invention.
Embodiment 4 (proportioning is a mol ratio)
In four-hole boiling flask, add 0.3 part of trimeric cyanamide, 0.2 part of urea and 1.8 parts of formaldehyde (37% aqueous solution), stir, regulate pH=8.5, heat to 70 ℃, reacted 50 minutes; Drop into 0.4 part of sodium bisulfite, 0.1 part of Sodium Pyrosulfite and a part of deionized water, regulate pH=10, heat temperature raising to 80 ℃ reacted 100 minutes; Cool to 50 ℃, regulate pH=4.5, reacted 100 minutes; Be warming up to 90 ℃, regulate pH=9, reaction 80min.Reduce to normal temperature, both got melamine high-efficiency water-reducing agent of the present invention.
Embodiment 5 (proportioning is a mol ratio)
In four-hole boiling flask, add 0.3 part of trimeric cyanamide, 0.2 part of urea and 1.8 parts of formaldehyde (37% aqueous solution), stir, regulate pH=8.5, heat to 70 ℃, reacted 50 minutes; Drop into 0.4 part of sodium bisulfite, 0.1 part of Sodium Pyrosulfite and a part of deionized water, regulate pH=10, heat temperature raising to 80 ℃ reacted 100 minutes; Cool to 50 ℃, regulate pH=4.5, reacted 120 minutes; Be warming up to 90 ℃, regulate pH=9, reaction 80min.Reduce to normal temperature, both got melamine high-efficiency water-reducing agent of the present invention.