阅读说明：本技术 一种核壳结构聚合物水泥改性剂、制备方法及水泥基材料 (Core-shell structure polymer cement modifier, preparation method and cement-based material ) 是由 陈建军 陈建春 叶家元 栾政斌 王宏霞 董刚 于 2020-07-10 设计创作，主要内容包括：本发明公开了一种核壳结构聚合物水泥改性剂、制备方法及水泥基材料,包括第一组分和第二组分；第一组分包括：苯乙烯,第一去离子水,乳化剂份,第一缓冲剂,第一引发剂；第二组分包括：种子乳液,第二去离子水,第二引发剂,丙烯酸丁酯第二缓冲剂。有益效果是水泥改性剂为乳液状态,乳液粒子的大小可控,粒径分布窄且易操作,重复性好,乳液粒子成膜温度较低,乳液粒子填充到水泥的孔洞中,可以在较宽的使用温度范围下凝聚成膜,对孔洞和裂缝起到封闭的作用,提高水泥的抗渗能力,提高水泥的耐久性；加入该水泥改性剂的水泥基材料流动性、保水性、粘结性、耐磨性、抗冻融性、防辐射性能以及力学强度和延伸性能较普通水泥都有显著提高。(The invention discloses a core-shell structure polymer cement modifier, a preparation method and a cement-based material, wherein the cement modifier comprises a first component and a second component; the first component comprises: styrene, first deionized water, an emulsifier part, a first buffering agent and a first initiator; the second component comprises: the emulsion comprises a seed emulsion, second deionized water, a second initiator and a butyl acrylate second buffering agent. The cement modifier is in an emulsion state, the size of emulsion particles is controllable, the particle size distribution is narrow and easy to operate, the repeatability is good, the film forming temperature of the emulsion particles is low, the emulsion particles are filled into holes of cement and can be condensed into a film in a wider using temperature range, the holes and cracks are sealed, the impermeability of the cement is improved, and the durability of the cement is improved; the cement-based material added with the cement modifier has obviously improved fluidity, water retention property, caking property, wear resistance, freeze-thaw resistance, radiation resistance, mechanical strength and extensibility compared with common cement.)

1. A core-shell structure polymer cement modifier is characterized in that: comprises a first component and a second component; the first component comprises the following components in parts by mass: 20-30 parts of styrene, 45-60 parts of first deionized water, 0.5-1.2 parts of an emulsifier, 0.05-1.5 parts of a first buffering agent and 0.15-0.3 part of a first initiator; the second component includes: 45-55 parts of seed emulsion, 45-60 parts of second deionized water, 0.15-0.3 part of second initiator, 25-35 parts of butyl acrylate and 0.04-0.08 part of second buffering agent.

2. The core-shell structure polymer cement modifier according to claim 1, characterized in that: the emulsifier is sodium dodecyl sulfate.

3. The core-shell structure polymer cement modifier according to claim 1, characterized in that: the first buffer and the second buffer are NaHCO₃。

4. The core-shell structure polymer cement modifier according to claim 1, characterized in that: the first initiator and the second initiator are potassium persulfate, which has great influence on emulsion stability, reaction rate and particle morphology and can eliminate homogeneous nucleation.

5. A method for preparing the core-shell structure polymer cement modifier according to any one of claims 1 to 4, which is characterized in that: the method comprises the following steps:

1) preparing a 'core' in the styrene-acrylic emulsion, namely a seed emulsion; accurately weighing styrene, first deionized water, an emulsifier, a first buffering agent and a first initiator according to the proportion; adding an emulsifier, a first buffering agent and first deionized water into a reactor, and stirring for dissolving; continuously heating to 70 ℃, adding styrene, continuously stirring, dissolving a first initiator in 10 parts of water, adding the first initiator into the water while stirring for 10min, and turning off the stirrer after 1h to obtain seed emulsion;

2) preparing a shell in the styrene-acrylic emulsion, namely PS-g-PBA latex; accurately weighing a seed emulsion, second deionized water, a second initiator, butyl acrylate and a second buffering agent according to the proportion, wherein the seed emulsion is obtained in the step 1); dissolving a second buffering agent in 10 parts of water, mixing the second buffering agent with the seed emulsion, and continuously heating to 70 ℃; dissolving a second initiator in 10 parts of water, mixing after reaching the temperature, then slowly dropwise adding butyl acrylate, reacting for 1h after all the butyl acrylate is dropwise added, and turning off a stirrer to obtain styrene-acrylic emulsion, namely PS-g-PBA latex; the polymer solids content was determined.

6. A cement-based material containing a core-shell structure polymer cement modifier is characterized in that: comprises the following components in parts by weight: 1.5-3 parts of styrene-acrylic emulsion, 25-35 parts of cement, 7-15 parts of water and 85-100 parts of sand; 1.5-3 parts of styrene-acrylic emulsion is the mass part of the core-shell structure polymer prepared by the preparation method of the core-shell structure polymer cement modifier in the claim 5, excluding water; the cement is ordinary portland cement; the sand is one or more of fine sand, medium sand and coarse sand.

Technical Field

The invention belongs to the technical field of building materials, and particularly relates to a core-shell structure polymer cement modifier, a preparation method of the core-shell structure polymer cement modifier, a cement-based material containing the core-shell structure polymer cement modifier and a preparation method of the cement-based material.

Background

Concrete and cement mortar are the most widely used and most used building materials worldwide. Concrete and cement mortar are basically non-uniform porous materials (the diameter of large pores is larger than 1 mu m, the diameter of capillary pores is between 0.1 and 1.0 mu m, and the diameter of fine pores is smaller than 0.1 mu m), and under the erosion action of external aggressive media such as carbon dioxide, water, chloride ions, sulfate and the like, the concrete and the cement mortar can be damaged in an accelerated way, so that the service life is greatly shortened. The main measures for improving the durability of concrete and cement mortar are to reduce the permeability and improve the impermeability. In the prior art, the impermeability of concrete and cement mortar is usually improved by using a core-shell structure polymer cement modifier, the particle diameter of the core-shell structure polymer is 0.1-1.0 μm, the core-shell structure polymer is added into the concrete and cement mortar, the particles of the core-shell structure polymer can fill the holes of the concrete and cement mortar, and when the use environment temperature is higher than the lowest film-forming temperature of the core-shell structure polymer emulsion, the core-shell structure polymer emulsion particles can be condensed into a film, thereby having a sealing effect on the holes and cracks. The cement modifier has the defects that the existing cement modifiers with core-shell structure polymers are generally in a soft core-shell structure, the film forming temperature of the core-shell structure polymers is high, and the film forming is difficult in the environment with high use temperature.

Disclosure of Invention

1. Technical problem to be solved

Aiming at the problems that the core-shell structure polymer cement modifier is in a soft core-shell structure, the film forming temperature is higher than the use environment temperature, and the film forming is difficult in the prior art, the invention aims to provide the core-shell structure polymer cement modifier, the preparation method and the cement-based material, wherein the cement modifier is in an emulsion state, the size of emulsion particles is controllable, the particle size distribution is narrow and easy to operate, the repeatability is good, the lowest film forming temperature of the emulsion particles can reach 22 ℃, the emulsion particles are filled into holes of cement, can be condensed into a film in a wider use temperature range, and have a sealing effect on the holes and cracks, so that the impermeability of the cement is improved, and the durability of the cement is improved; the cement-based material added with the cement modifier has obviously improved fluidity, water retention property, caking property, wear resistance, freeze-thaw resistance, radiation resistance, mechanical strength and extensibility compared with common cement.

2. Technical scheme

In order to achieve the purpose, the invention adopts the following technical scheme:

a core-shell structure polymer cement modifier is characterized by comprising a first component and a second component; the first component comprises the following components in parts by mass: 20-30 parts of styrene, 45-60 parts of first deionized water, 0.5-1.2 parts of an emulsifier, 0.05-1.5 parts of a first buffering agent and 0.15-0.3 part of a first initiator; the second component includes: 45-55 parts of seed emulsion, 45-60 parts of second deionized water, 0.15-0.3 part of second initiator, 25-35 parts of butyl acrylate and 0.04-0.08 part of second buffering agent.

In a specific embodiment of the present invention, the emulsifier is sodium dodecyl sulfate, which plays roles of emulsification, solubilization and dispersion during the polymerization of the first component, plays an important role in the stability of emulsion polymerization and the performance of the synthesized product, and can keep the charge density on the surface of the emulsion particles unchanged.

In a specific embodiment of the present invention, the first buffer and the second buffer are NaHCO₃And the pH value of the system is adjusted to maintain stability.

In a specific embodiment of the present invention, the first initiator and the second initiator are potassium persulfate, which has great influence on emulsion stability, reaction rate and particle morphology, and can eliminate homogeneous nucleation.

The invention also aims to provide a preparation method of the core-shell structure polymer cement modifier, which is characterized by comprising the following steps:

1) preparing a 'core' in the styrene-acrylic emulsion, namely a seed emulsion; accurately weighing styrene, first deionized water, an emulsifier, a first buffering agent and a first initiator according to the proportion; adding an emulsifier, a first buffering agent and first deionized water into a reactor, and stirring for dissolving; continuously heating to 70 ℃, adding styrene, continuously stirring, dissolving a first initiator in 10 parts of water, adding the first initiator into the water while stirring for 10min, and turning off the stirrer after 1h to obtain seed emulsion; the water used for dissolving the first initiator is added with water;

2) preparing a shell in the styrene-acrylic emulsion, namely PS-g-PBA latex; accurately weighing a seed emulsion, second deionized water, a second initiator, butyl acrylate and a second buffering agent according to the proportion, wherein the seed emulsion is obtained in the step 1); dissolving a second buffering agent in 10 parts of water, mixing the second buffering agent with the seed emulsion, and continuously heating to 70 ℃; dissolving a second initiator in 10 parts of water, mixing after reaching the temperature, then slowly dropwise adding butyl acrylate, reacting for 1h after all the butyl acrylate is dropwise added, and turning off a stirrer to obtain styrene-acrylic emulsion, namely PS-g-PBA latex; detecting the polymer solid content; the second buffer and the second initiator are dissolved by using water as external water.

The invention also aims to provide a cement-based material containing the core-shell structure polymer cement modifier, which is characterized by comprising the following components in parts by mass: 1.5-3 parts of styrene-acrylic emulsion, 25-35 parts of cement, 7-15 parts of water and 85-100 parts of sand; 1.5-3 parts of styrene-acrylic emulsion is mass parts of core-shell structure polymer solid excluding water; the cement is ordinary portland cement; the sand is one or more of fine sand, medium sand and coarse sand; the water is ordinary water.

A method for preparing a cement-based material containing a core-shell structure polymer cement modifier comprises the following steps: accurately weighing styrene-acrylic emulsion, cement, water and sand according to the proportion; mixing cement, water, sand and styrene-acrylic emulsion, and stirring to obtain the cement-based material containing the core-shell structure polymer cement modifier.

3. Advantageous effects

The invention has the beneficial effects that: the cement modifier of the core-shell structure polymer, namely the styrene-acrylic emulsion, is obtained by a seed emulsion graft polymerization technology, and the technology has the advantages that the size of latex particles can be effectively controlled, the particle size distribution of the obtained polymer latex particles is narrow, the operation is easy, the repeatability is good, and particularly, special products with the core-shell structure can be easily obtained; the styrene-acrylic emulsion is PS-g-PBA emulsion, the inner layer and the outer layer of PS-g-PBA emulsion particles are grafted, the grafted copolymer with the core-shell structure has a plurality of excellent performances compared with a random copolymer, and the emulsion can also obviously improve the fluidity, water retention property, cohesiveness, wear resistance, freeze-thaw resistance, radiation resistance, mechanical strength and extensibility of the cement-based material under the condition that the raw material compositions are completely the same; the PS-g-PBA emulsion belongs to a soft shell and hard core structure, and the lowest film forming temperature can reach 22 ℃, so that styrene-acrylic emulsion particles can be condensed into a film under the condition of low use temperature, and the film can seal holes and cracks; the cement-based material containing the core-shell structure polymer cement modifier is impervious cement, and the styrene-acrylic emulsion particles can fill holes in the cement to improve the impermeability of the cement, so that the cement has better durability;

Detailed Description

The present invention will be described in detail with reference to specific examples.