Application research of styrene-butadiene latex_Kain Industrial Additive

Overview^[1][2]

Styrene-butadiene latex is a copolymer latex formed by emulsion polymerization of butadiene and styrene. The ratio of butadiene to styrene ranges from 75:25 to 15:85, and the ratio range is quite wide. Furthermore, due to different emulsifiers, stabilizers, and temperatures during polymerization, many varieties with different properties can be produced. Even if the varieties are the same, There are also different models based on particle size. Therefore, various brands of products also differ in terms of use and performance.

Applied Research^[2]

At present, polymer cement concrete has become an important part of high-performance concrete research. Liu Fang et al. used a polymer emulsion (styrene-butadiene latex) to modify high-performance concrete and studied the effects of different styrene-butadiene latex addition amounts on the basic mechanical properties, toughness, autogenous shrinkage performance and resistance to chloride ion penetration of cement concrete. Performance impact.

The experimental results show that the compressive strength of cement concrete modified by styrene-butadiene latex decreases with the increase in the amount of styrene-butadiene latex added; while the addition of styrene-butadiene latex has an impact on the splitting tensile strength and flexural strength of concrete. The strength and toughness are greatly improved, and the enhancement effect is most obvious when the content is 15%. The increase in splitting tensile strength and flexural strength reaches 17.4% and 23.8% respectively; when the content is 10%, the toughness is improved. The degree of index is the highest, with an increase of 71.1%. The total shrinkage value of styrene-butadiene latex modified concrete after pouring for 24 hours gradually decreases with the increase of the styrene-butadiene latex content. The total shrinkage value decreases when the content of styrene-butadiene latex is 15%. Up to 35%; at the same time, the modified cement concrete’s resistance to chloride ion diffusion has been improved, and its anti-permeability performance has also been improved.

Wang Yongming and others used butadiene and styrene as raw materials, using high and low temperature composite technology to prepare high solid content (60%) styrene-butadiene rubber emulsion, and then prepared a uniform particle size distribution (<1mm) by coagulation method. Powdered styrene-butadiene rubber (PSBR), the cohesion principle was discussed, and the preparation process of powdered styrene-butadiene rubber was optimized. The morphology changes during the formation stage of powdered styrene-butadiene rubber were studied by polarizing microscopy.

The results show that the flocculant, coagulant and isolating agent in the coagulation stage have the greatest impact on the morphology of PSBR. The compound release agent (sodium stearate, sodium oleate and silicone oil) has the best isolation effect. Sodium chloride is used as the flocculant [adding amount is 1.3% (based on latex quality, the same below)], and magnesium sulfate is When the coagulant (added amount is 2.5%), the styrene-butadiene latex has the best powdering effect and becomes a powdered rubber with uniform particle size. When PSBR modified 70# base asphalt is used and the PSBR addition amount is 1.0% (based on the quality of the asphalt, the same below), the softening point of the modified asphalt increases from 47.6℃ of 70# base asphalt to 51.8℃, 5℃ The ductility is increased to more than 100cm, which is better than the current styrene-butadiene rubber (SBR) rubber powder modified asphalt.

Preparation^[4]

CN201610273186.7 provides a styrene-butadiene latex for road emulsified asphalt modification, specifically a composite styrene-butadiene latex, which is composed of two components: modified styrene-butadiene latex and a cross-linking agent. Modified styrene-butadiene latex is a cationic styrene-butadiene latex with an average particle size of 320nm to 420nm and a solid content of ≥60%. Its main components include: butadiene-styrene copolymer with high gel content as the core and low coagulation content. The polymer copolymer of butadiene-styrene-epoxypropyl methacrylate-KH-570 with epoxy and alkoxysilyl groups in the side chain is a latex particle composed of a shell, anionic/non- Ionic composite emulsifier, tertiary amine non-ionic emulsifier and water; the cross-linking agent is 40% KH-560 silane coupling agent aqueous emulsion; the weight ratio of modified styrene-butadiene latex and cross-linking agent is: 1: 0.06～1:0.07.

Including the following processes:

a. Emulsion polymerization:

The raw materials consist of the following components by weight:

Butadiene: 72 to 80 parts; styrene: 20 to 28 parts; glycidyl methacrylate: 2 to 4 parts; silane coupling agent KH-570 or silane coupling agent KH-151: 1 ~2 parts; dodecyl mercaptan: 0.3~0.7 parts; at least one anionic/nonionic composite emulsifier containing potassium or sodium carboxylate groups: 1.5~4.0 parts; ammonium persulfate: 0.2~0.3 parts ; Sodium sulfite: 0.1 to 0.15 parts; Alkali metal inorganic salt latex water phase density adjuster: 0.3 to 0.6 parts; Deionized water: 100 to 130 parts; Composite terminator: 0.02～0.04 copies;

Polymerization process: Use a polymerization kettle, add the above raw materials into the polymerization kettle under vacuum to prepare a basic emulsion;

b. Removal of residual monomers – agglomeration: Pour the product of step (a) into a degassing kettle and use direct steam stripping to remove residual monomers; add 0.1 to 0.5 parts of aqueous agglomeration agent solution and continue degassing ≥30 minutes to obtain large particle size anionic latex;

c. Ionic conversion: Pour the product of step (b) into the ionic conversion kettle, slowly add an aqueous solution of a tertiary amine nonionic emulsifier diluted to 20% to 30% by spraying while stirring, and then Slowly add dilute hydrochloric acid by spraying method to adjust the pH of the system to 4-5 to complete the ionic conversion and obtain large particle size cationic styrene-butadiene latex;

Among them, the tertiary amine nonionic emulsifier is a mixture of 1 to 2 parts of rosin amine polyoxyethylene ether and 1 to 2 parts of fatty amine polyoxyethylene ether;

d. Centrifugal concentration; continuously introduce the product of step (c) into a disc latex separator, and add an aqueous emulsion containing 0.8 to 1.0 parts of antioxidant to the concentrated styrene-butadiene latex to obtain modified styrene-butadiene latex: Cationic styrene-butadiene latex with an average particle size of 320nm to 420nm and a solid content of ≥60%.

Main reference materials

[1] Practical Fine Chemical Dictionary

[2] Liu Fang, Wang Baomin, Yuan Xiaosa, Wang Yonggang, Li Ming. Experimental analysis of mechanical properties and durability of styrene-butadiene latex modified cement concrete [J]. Functional Materials, 2019, 50(06): 6167-6173 .

[3] Wang Yongming, Shen Kaihua. Powder preparation and application of styrene-butadiene latex for modified asphalt [J/OL]. Fine Chemicals: 1-9[2019-09-07]. https://doi.org /10.13550/j.jxhg.20180812.

[4] [China invention, China invention authorization] CN201610273186.7 A styrene-butadiene latex for road emulsified asphalt modification and its preparation method