Background technology
Mix an amount of water reducer in the concrete, can significantly improve the concrete over-all properties of serviceability and sclerosis back of fresh concrete.Poly carboxylic acid series water reducer is as new generation product, has low-dosage, high water reducing rate, distinct advantages such as slow setting, low slump loss, environmental protection not.Be applicable to special concretes such as normal concrete and high-strength, self-compacting, clear-water concrete.
The synthesis technique of poly carboxylic acid series water reducer in the market, mainly be by monomers such as MPEG, methacrylic acids, under stopper and catalyst action, be heated to 120 ℃~140 ℃, esterification 5~8 hours adds an amount of monomer and initiators such as methacrylic acid in the esterification products that obtains, feed nitrogen, reacted 5~8 hours down at 70 ℃~90 ℃, reaction finishes the back and regulates the pH value with sodium hydroxide.The used starting material methacrylic acid of this type of technology price height causes the poly carboxylic acid series water reducer cost to increase, and compares with present widely used naphthalene water reducer, and difference in selling prices is big, lacks the market competitiveness.And this synthesis technique is complicated, the difficult control of esterification process, and esterification products is very big to the performance impact of polyreaction and the finished product.Now,, the more important thing is to reduce cost, simplify technology, enhance one's market competitiveness the not single pursuit good comprehensive performances of the research of poly carboxylic acid series water reducer.Manage guaranteeing that with the higher-priced methacrylic acid of low price acid substitution water reducer has on the high performance basis, save cost.At present, the domestic temporary transient not achievement in research of relevant synthesis technique aspect.
Summary of the invention
The object of the present invention is to provide a kind of synthesis technique is simple, the prices of raw and semifnished materials are cheap, product performance are stable novel poly carboxylic acid series water reducer and synthetic method thereof.
The poly carboxylic acid series water reducer that the present invention proposes, with allyl polyglycol (APEG) is basic raw material, by allyl polyglycol (molecular weight 600~2500), maleic anhydride, methyl acrylate, ammonium persulphate, stannous sulfate, sodium hydroxide and water, the synthetic acquisition, concrete synthesis step is:
1) raw material ratio: press mass ratio 500: (0.5~180): (0.5~150): (200~1500), take by weighing starting material allyl polyglycol, maleic anhydride, methyl acrylate and water, add reactor successively, mix, stir;
2) add thermal synthesis: in reactor, feed shielding gas nitrogen, plug prolong, add at least a in ammonium persulphate and the stannous sulfate, the add-on of ammonium persulphate is 1~10% of a monomer total mass, the add-on of stannous sulfate is a monomer total mass 1~10%, under 50 ℃~100 ℃, reacted 4~10 hours; The monomer total mass here is meant APEB, the inferior acid anhydrides of horse and three kinds of sums of methyl acrylate;
3) neutralization: after the question response thing cooling, be sodium hydroxide adjusting pH value to 6~8 of 50% with concentration.
Among the present invention, the amount ratio of former material allyl polyglycol, maleic anhydride, methyl acrylate and water is preferably 500: (10-100): (10-90): (400-1000).
Among the present invention, the consumption of ammonium persulphate is preferably the 3%-8% of monomer total mass, and the consumption of stannous sulfate is preferably the 3%-8% of monomer total mass.
Among the present invention, replace MPEG with APEG, APEG has the PEO side chain, produces the steric restriction effect of physics, prevents the cement granules cohesion, keeps dispersed, the more important thing is APEG can with the maleic anhydride polyreaction of low price.Maleic anhydride can strengthen water-reducing effect, and price is less than 10000 yuan/ton, and at present in the technology used methacrylic acid price more than 20000 yuan/ton.Methyl acrylate not only has good water-reducing property, and can add the anchor force of strength water-reducing agent at cement particle surface.Ammonium persulphate and stannous sulfate are initiator, can make each monomer participate in polyreaction.Sodium hydroxide is used for regulating pH value.
Synthetic product of the present invention is a light yellow transparent liquid, concentration is 30%~65%, in concrete, mix a small amount of (0.5%-5% that is generally the cement gross weight gets final product), make it have high water reducing rate and good slump maintenance, can satisfy higher construction requirement, and improve concrete strength to a certain extent.Comparing with existing processes, is the synthesis technique reaction times weak point of raw-material novel poly carboxylic acid series water reducer with APEG, and starting material are cheap, and technology is simple, the stable performance of reaction product.
The present invention can produce for admixture factory, and one-step polymerization and getting is with low cost, is widely used in Important Project and various common engineerings such as bridge, dam, airport.
Embodiment
Embodiment 1; adopt following synthesis technique: APEG (molecular weight 1000) 31.00% (mass percent with allyl polyglycol (molecular weight 1000) for raw-material novel poly carboxylic acid series water reducer; as follows), maleic anhydride 4.10%, methyl acrylate 4.90%, water 60.00%; add reactor successively; feed nitrogen protection, add the ammonium persulphate of monomer total mass 8%, reacted 6 hours down at 90 ℃; add 50% sodium hydroxide solution, regulate pH value to 7.Mix this water reducer of by mass of cement 1.0%, can make water cement ratio is that 0.29 flowing degree of net paste of cement is 290mm, not loss in 6 hours.
Embodiment 2; adopt following synthesis technique: APEG (molecular weight 2500) 28.50% (mass percent with allyl polyglycol (molecular weight 2500) for raw-material novel poly carboxylic acid series water reducer; as follows), maleic anhydride 5.55%, methyl acrylate 5.95%, water 60.00%; add reactor successively; feed nitrogen protection, add the stannous sulfate of monomer total mass 6%, reacted 6 hours down at 90 ℃; add 50% sodium hydroxide solution, regulate pH value to 7.Mix this water reducer of by mass of cement 1.2%, can make water cement ratio is that 0.29 flowing degree of net paste of cement is 275mm, not loss in 5 hours.
Embodiment 3; with allyl polyglycol is that raw-material novel poly carboxylic acid series water reducer adopts following synthesis technique: APEG (molecular weight 1500) 33.50% (mass percent; as follows), maleic anhydride 3.50%, methyl acrylate 3.00%, water 60.00%; feed nitrogen protection; the ammonium persulphate that adds monomer total mass 5%, the stannous sulfate of adding monomer total mass 4% reacted 7 hours down at 95 ℃; add 50% sodium hydroxide solution, regulate pH value to 7.Mix this water reducer of by mass of cement 0.8%, can make water cement ratio is that 0.29 flowing degree of net paste of cement is 270mm, not loss in 5 hours.