阅读说明：本技术 一种聚羧酸减水剂及其制备方法 (Polycarboxylate superplasticizer and preparation method thereof ) 是由 王志强 陈烽 鲁江 张辉 宋南京 吕晓 刘秀敏 冯恩娟 秦尤敏 张晓娇 于 2020-06-23 设计创作，主要内容包括：本发明公开一种聚羧酸减水剂,属于水泥外加剂技术领域。本发明减水剂包括以下重量份的原料制备而成：聚醚300-400份、小单体15-45份、引发剂10-20份、链转移剂1.5-5份、液碱1-5份、增效剂1-5份、改性纤维0.5-1.5份、去离子水600-1200份。本发明提供一种聚羧酸系减水剂的常温合成方法,通过复配改性纤维和增效剂,可大幅提升本发明减水剂性能,且可常温合成,大大降低的生产成本,所得减水剂适应性强,保坍效果好。(The invention discloses a polycarboxylate superplasticizer, belonging to the technical field of cement admixtures. The water reducing agent is prepared from the following raw materials in parts by weight: 400 portions of polyether 300-containing material, 15-45 portions of small monomer, 10-20 portions of initiator, 1.5-5 portions of chain transfer agent, 1-5 portions of liquid alkali, 1-5 portions of synergist, 0.5-1.5 portions of modified fiber and 1200 portions of deionized water 600-containing material. The invention provides a normal-temperature synthesis method of a polycarboxylic water reducer, which can greatly improve the performance of the polycarboxylic water reducer by compounding modified fibers and a synergist, can be synthesized at normal temperature, greatly reduces the production cost, and has strong adaptability and good slump retaining effect.)

1. The polycarboxylate superplasticizer is characterized by being prepared from the following raw materials in parts by weight: 400 portions of polyether 300-containing material, 15-45 portions of small monomer, 10-20 portions of initiator, 1.5-5 portions of chain transfer agent, 1-5 portions of liquid alkali, 1-5 portions of synergist, 0.5-1.5 portions of modified fiber and 1200 portions of deionized water 600-containing material.

2. The polycarboxylate water reducer according to claim 1, wherein the polyether is one of methallyl polyoxyethylene ether or prenyl polyoxyethylene ether.

3. The polycarboxylate water reducer according to claim 1, wherein the polyether is methyl allyl polyoxyethylene ether and isoamylol polyoxyethylene ether in a mass ratio of 5: 8 and mixing.

4. The polycarboxylate water reducer according to claim 1, wherein the small monomer is one or more of acrylic acid, methacrylic acid, sodium allyl sulfonate and sodium methallyl sulfonate.

5. The polycarboxylate water reducer according to claim 1, wherein the initiator is one or more of hydrogen peroxide, vitamin C, ferrous sulfate and ammonium persulfate.

6. The polycarboxylate water reducer according to claim 1, wherein the chain transfer agent is one or more of 2, 4-diphenyl-4-methyl-1-pentene, sodium hypophosphite and sodium aluminum phosphate.

7. The polycarboxylate water reducer according to claim 1, characterized in that the synergist is sodium gluconate.

8. The polycarboxylate water reducer according to claim 1, wherein the modified fibers are prepared by the following method:

1) pretreatment: cutting pineapple leaf fibers into small sections with the length of 0.5-1cm, soaking the small sections in a benzene-absolute ethyl alcohol mixed solution with the volume ratio of 1:1 for 24 hours, taking out the small sections, airing the small sections, respectively washing the small sections with absolute ethyl alcohol and distilled water, and then drying the small sections in a shade; soaking the fiber in 15% sodium hydroxide solution for 2h, wherein the weight ratio of the fiber to the sodium hydroxide solution is 1:20, and continuously stirring; after soaking, washing the fibers to be neutral by using distilled water, airing at room temperature in a ventilating way, grinding the fibers by using a plant sample grinder until the particle size is less than 1 mu m, and sealing for later use to obtain the pretreated pineapple leaf fibers;

2) deionized water and a silane coupling agent Si-563 are taken according to the mass ratio of 2:1, the silane coupling agent Si-563 is added into the deionized water and stirred until the silane coupling agent Si-563 is completely dissolved, the pretreated pineapple leaf fiber obtained in the step (1) is added, the pineapple leaf fiber is soaked for 12 hours and then placed in a drying oven to be dried for more than 24 hours, and modified fiber is obtained.

9. The preparation method of the polycarboxylate superplasticizer according to any one of claims 1 to 8, characterized by comprising the following preparation steps:

1) the preparation method of the material A comprises the following steps: at room temperature, taking 15-45 parts of small monomer and 400 parts of deionized water 200-plus, sequentially adding the small monomer and the deionized water into a triangular flask, uniformly mixing, and sealing by using a plastic film for later use;

2) the preparation method of the material B comprises the following steps: at room temperature, sequentially adding 1.5-5 parts of chain transfer agent and 400 parts of deionized water 200-400 parts into a triangular flask, uniformly mixing, and sealing with a plastic film for later use;

3) preparing modified fiber: cutting pineapple leaf fibers into small sections with the length of 0.5-1cm, soaking the small sections in a benzene-absolute ethyl alcohol mixed solution with the volume ratio of 1:1 for 24 hours, taking out the small sections, airing the small sections, respectively washing the small sections with absolute ethyl alcohol and distilled water, and then drying the small sections in a shade; soaking the fiber in 15% sodium hydroxide solution for 2h, wherein the weight ratio of the fiber to the sodium hydroxide solution is 1:20, and continuously stirring; after soaking, washing the fibers to be neutral by using distilled water, airing at room temperature in a ventilating way, grinding the fibers by using a plant sample grinder until the particle size is less than 1 mu m, and sealing for later use to obtain the pretreated pineapple leaf fibers; taking deionized water and a silane coupling agent Si-563 according to the mass ratio of 2:1, adding the silane coupling agent Si-563 into the deionized water, stirring until the silane coupling agent Si-563 is completely dissolved, adding the pretreated pineapple leaf fiber obtained in the step (1), soaking for 12 hours, and drying in a drying oven for more than 24 hours to obtain modified fiber;

4) adding the rest deionized water into a four-neck flask with a stirrer, starting the stirrer, adding polyether, and stirring and mixing uniformly; adding an initiator into the flask, and uniformly stirring; simultaneously dripping A, B materials by using a peristaltic pump, controlling the dripping time of the material A for 2-3h, controlling the dripping time of the material B for 2.5-4h, and keeping the temperature for 1-1.5h after the dripping is finished; adding liquid alkali to adjust the pH value to 6-7; adding the modified fiber and the synergist, mixing uniformly to obtain the finished product polycarboxylic acid water reducing agent, and packaging and warehousing.

Technical Field

The invention belongs to the technical field of cement additives, and particularly relates to a polycarboxylic acid water reducing agent and a preparation method thereof.

Background

Concrete as a building functional material is prepared by mixing and stirring cement, granular aggregates (stone, sand and the like), water, mineral admixture, chemical admixture and other components according to a certain proportion. Because of its advantages of good durability, high compressive strength, low price and abundant raw materials, it is widely used in civil engineering (such as industrial buildings, civil buildings, water conservancy harbors, etc.) and geothermal development engineering.

The chemical admixture is used as an important component in cement concrete, and can obviously improve the properties of the cement concrete, such as strength, stability, durability and the like, by adding a small amount of the chemical admixture into the cement concrete. At present, various chemical admixtures are available on the market, and the common chemical admixtures are mainly an early strength agent, a retarder, an air entraining agent, an expanding agent, an accelerator, a pumping aid and a water reducing agent. The water reducing agent can be successfully included in one of the essential components of the cement concrete because the water reducing agent is most widely used in the cement concrete admixture and has the largest use amount (about three quarters of the total amount of the admixture).

The polycarboxylate superplasticizer is a high molecular polymer which is formed by copolymerizing unsaturated monomers containing carboxyl and unsaturated monomers containing other functional groups and can ensure that concrete has excellent performances in the aspects of water reduction, collapse retention, environmental protection and the like. The polycarboxylic acid high-performance water reducing agent has the advantages of low doping amount, high water reducing rate, controllable molecular structure, good dispersibility, environmental friendliness, strong adaptability and the like, is valued and researched by broad scholars and experts, and is widely applied to engineering construction in various fields, so that the polycarboxylic acid high-performance water reducing agent becomes a future development trend of concrete admixtures, and the research on the polycarboxylic acid high-performance water reducing agent is an inevitable requirement in the field of concrete.

The traditional polycarboxylic acid water reducing agent is mainly synthesized at 40-70 ℃, because the traditional polycarboxylic acid water reducing agent is not synthesized at normal temperature and needs a heating system, the cost is higher, and meanwhile, most of chain transfer agents are mercapto acid toxic substances, and long-time contact can cause poisoning and damage to human health, so that the development of a non-toxic or low-toxicity and high-performance water reducing agent synthesis mode is very important at present.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a non-toxic or low-toxicity high-performance water reducing agent and a normal-temperature synthesis method thereof. The water reducing agent adopts nontoxic or low-toxicity raw materials and can be synthesized at normal temperature, so that the problems of poor environment-friendly effect, low cost performance and poor performance expectation of the traditional water reducing agent synthesis are solved.

The technical scheme adopted by the invention is as follows:

the polycarboxylate superplasticizer is prepared from the following raw materials in parts by weight: 400 portions of polyether 300-containing material, 15-45 portions of small monomer, 10-20 portions of initiator, 1.5-5 portions of chain transfer agent, 1-5 portions of synergist, 1-5 portions of liquid alkali, 0.5-1.5 portions of modified fiber and 1200 portions of deionized water 600-containing material.

Preferably, the polyether is one of methyl allyl polyoxyethylene ether or prenol polyoxyethylene ether.

Preferably, the polyether is methyl allyl polyoxyethylene ether and isoamylol polyoxyethylene ether according to a mass ratio of 5: 8 and mixing.

Preferably, the small monomer is one or more of acrylic acid, methacrylic acid, sodium allyl sulfonate and sodium methallyl sulfonate.

Preferably, the initiator is one or more of hydrogen peroxide, vitamin C, ferrous sulfate and ammonium persulfate.

Preferably, the chain transfer agent is one or more of 2, 4-diphenyl-4-methyl-1-pentene, sodium hypophosphite and sodium aluminum phosphate.

Preferably, the synergist is sodium gluconate.

Preferably, the modified fiber is prepared by the following method:

1) pretreatment: cutting pineapple leaf fibers into small sections with the length of 0.5-1cm, soaking the small sections in a benzene-absolute ethyl alcohol mixed solution with the volume ratio of 1:1 for 24 hours, taking out the small sections, airing the small sections, respectively washing the small sections with absolute ethyl alcohol and distilled water, and then drying the small sections in a shade; soaking the fiber in 15% sodium hydroxide solution for 2h, wherein the weight ratio of the fiber to the sodium hydroxide solution is 1:20, and continuously stirring; after soaking, washing the fibers to be neutral by using distilled water, airing at room temperature in a ventilating way, grinding the fibers by using a plant sample grinder until the particle size is less than 1 mu m, and sealing for later use to obtain the pretreated pineapple leaf fibers;

2) deionized water and a silane coupling agent Si-563 are taken according to the mass ratio of 2:1, the silane coupling agent Si-563 is added into the deionized water and stirred until the silane coupling agent Si-563 is completely dissolved, the pretreated pineapple leaf fiber obtained in the step (1) is added, the pineapple leaf fiber is soaked for 12 hours and then placed in a drying oven to be dried for more than 24 hours, and modified fiber is obtained.

A preparation method of a polycarboxylate superplasticizer comprises the following preparation steps:

1) the preparation method of the material A comprises the following steps: at room temperature, taking 15-45 parts of small monomer and 400 parts of deionized water 200-plus, sequentially adding the small monomer and the deionized water into a triangular flask, uniformly mixing, and sealing by using a plastic film for later use;

2) the preparation method of the material B comprises the following steps: at room temperature, sequentially adding 1.5-5 parts of chain transfer agent and 400 parts of deionized water 200-400 parts into a triangular flask, uniformly mixing, and sealing with a plastic film for later use;

3) preparing modified fiber: cutting pineapple leaf fibers into small sections with the length of 0.5-1cm, soaking the small sections in a benzene-absolute ethyl alcohol mixed solution with the volume ratio of 1:1 for 24 hours, taking out the small sections, airing the small sections, respectively washing the small sections with absolute ethyl alcohol and distilled water, and then drying the small sections in a shade; soaking the fiber in 15% sodium hydroxide solution for 2h, wherein the weight ratio of the fiber to the sodium hydroxide solution is 1:20, and continuously stirring; after soaking, washing the fibers to be neutral by using distilled water, airing at room temperature in a ventilating way, grinding the fibers by using a plant sample grinder until the particle size is less than 1 mu m, and sealing for later use to obtain the pretreated pineapple leaf fibers; taking deionized water and a silane coupling agent Si-563 according to the mass ratio of 2:1, adding the silane coupling agent Si-563 into the deionized water, stirring until the silane coupling agent Si-563 is completely dissolved, adding the pretreated pineapple leaf fiber obtained in the step (1), soaking for 12 hours, and drying in a drying oven for more than 24 hours to obtain modified fiber;

4) adding the rest deionized water into a four-neck flask with a stirrer, starting the stirrer, adding polyether, and stirring and mixing uniformly; adding an initiator into the flask, and uniformly stirring; simultaneously dripping A, B materials by using a peristaltic pump, controlling the dripping time of the material A for 2-3h, controlling the dripping time of the material B for 2.5-4h, and keeping the temperature for 1-1.5h after the dripping is finished; adding liquid alkali to adjust the pH value to 6-7; adding the modified fiber and the synergist, mixing uniformly to obtain the finished product polycarboxylic acid water reducing agent, and packaging and warehousing.

Advantageous effects

The invention provides a normal-temperature synthesis method of a polycarboxylic acid water reducing agent, which reduces the toxic effect of raw materials in the traditional process in the synthesis process by improving a basic formula and adopting a novel chain transfer agent. By adding the modified fibers, the adhesion degree between the cements can be improved, and the later strength of the cements is improved. And the existence of the synergist can complex calcium ions in the cement to form a calcium coordination complex, reduce the concentration of the calcium ions in a liquid phase, and reduce the formation of C-H-S gel particles, thereby slowing down the hydration speed of the cement. Meanwhile, the existence of the modified fiber can also promote the coordination of cement calcium ions and carboxylate radicals in the water reducing agent molecules, inhibit the hydration of cement and improve the dispersion performance of cement molecules. By compounding the modified fiber and the synergist, the performance of the water reducer can be greatly improved, the water reducer can be synthesized at normal temperature, the production cost is greatly reduced, the obtained water reducer has strong adaptability, and the slump retaining effect is good.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments, but is not limited thereto.