UV-shielding material based on Mg—Al layered double hydroxide and its application in anti-ageing asphalt

A UV-shielding material based on Mg—Al Layered Double Hydroxide (LDH) and its application in improving anti-UV ageing of asphalt, the UV-shielding material based on Mg—Al LDH having a multi-level structure, and comprising:

• layer and interlayer carbonate anion that is a layered anionic clay with a hexagonal system,
• a composition of the UV-shielding material comprising:
• Mg1-xAlx(OH)2(CO3)x/2.mH2O, wherein x is a ratio of metal, 0.2≦x≦0.33, m is a number of crystal water in a range of 0≦m≦2;
• a particle size of the UV-shielding material based on Mg—Al LDH in a, b-axis direction in the unit cell is 0.05-5 μm and in c-axis direction is 0.06-0.250 μm,
• the UV-shielding material based on Mg—Al LDH comprising 10 to 200 layers;
• the UV-shielding material based on Mg—Al LDH being organic-surface modified to increase a compatibility with the asphalt, wherein a modifier is carboxymethyl based cellulose, lignin sulfonate, olefin sulfonate, petroleum sulfonate, succinate sulfonate, silane coupling agent, titanate coupling agent, or aluminum coupling agent;
• and a modification method is wet or dry method;
• and
• the organic surface modified UV-shielding material based on Mg—Al LDH used for a preparation of the anti-ageing asphalt including:
• the organic surface modified UV-shielding material based on Mg—Al LDH mixed with asphalt with a mass ratio of the organic surface modified UV-shielding material based on Mg—Al LDH:asphalt=0.01-0.1:1, and wherein a softening point of the anti-ageing asphalt is 40-50° C. and a penetration is more than 60 dmm under 25° C. after having been stirred evenly at 150-180° C.;
• wherein the UV-shielding material based on Mg—Al LDH prepared by a process comprising:
• dissolving soluble magnesium and aluminum with a mole ratio of magnesium:aluminum=2-4 in deionized water to obtain a mixed salt solution with [Mg2+]=0.1-2 mol/L;
• dissolving NaOH and Na2CO3 in deionized water to obtain a mixed alkali solution with n(NaOH)/[n(Mg2+)+n(Al3 +)]=1.8-2.5 and n(Na2CO3)/n(Al3+)=1-3, wherein a volume of the mixed alkali solution is 0.5 to 2 times of the mixed salt solution, and n(NaOH), n(Mg2+), n(Al3+), n(Na2CO3) is the mole of NaOH, Mg2+, Al3+, Na2CO3;
• adding the mixed alkali solution and the mixed salt solution into a rotating liquid film reactor to obtain a slurry;
• adding a template octane and a sodium dodecyl sulfate with a mole ratio of octane:sodium dodecyl sulfate=0.5-2 into the slurry with 0.1-5% mass of a solid slurry;
• stirring the slurry in a flask at 80-130° C. for 0.1-48 h and then washing and drying the slurry to obtain the UV-shielding material based on Mg—Al LDH, or
• the UV-shielding material based on Mg—Al LDH prepared by a process comprising:
• dissolving a soluble magnesium and aluminum with a mole ratio of magnesium:aluminum=2-4 in deionized water to obtain a mixed salt solution with [Mg2+]=0.1-0.8 mol/L;
• dissolving NaOH and Na2CO3 in deionized water to obtain a mixed alkali solution with n(NaOH)/[n(Mg2+)+n(Al3+)]=1.8-2.5 and n(Na2CO3)/n(Al3+)=1-3, wherein the volume of the mixed alkali solution is 0.5 to 2 times of the mixed salt solution, and n(NaOH), n(Mg2+), n(Al3+), n(Na2CO3) is the mole of NaOH, Mg2+, Al3+, Na2CO3;
• adding the mixed salt solution and the mixed alkali solution into a rotating liquid film reactor to obtain a slurry;
• stirring the slurry in a flask at 130-200° C. for 12-72 h and then washing and drying the slurry to obtain the UV-shielding material based on Mg—Al LDH.