Titanium dioxide is the most widely used whitening pigment in the world and has been linked to adverse health effects, particularly genotoxicity and intestinal inflammation. It is applied as food coloring and a whitening agent to a wide variety of foods, including chewing gum, cakes, candies, breads and ice cream.
Last Friday, the domestic rutile and anatase titanium dioxide new single price was stable, and the overall transaction focus of the market moved up. Titanium dioxide factory work normally, part of the output of early orders, the spot supply has increased accordingly; And buyers still have inventory digestion, the current mentality turned to wait-and-see. The volume of new orders in the market is limited.The key factors affecting the current market price change1.
The vitaminB2@TiO2NPs were obtained at room temperature, by a method developed after trying several ratios of reactants. Briefly, 0.02 g of P25TiO2NPs were dispersed in 1 mL of ultra-pure water and stirred in a Vortex. Next, 200 μl of vitamin B2 dissolved in ultra-pure water (5.3 × 10−3 M) were added to 200 μL of P25TiO2NPs and the mixture was ultrasonicated for 1 hour to achieve a deep-yellow homogeneous suspension. The pellet obtained after centrifuging the suspension for 10 min at 4500 rpm was resuspended in ultrapure water, centrifuged again, and then lyophilized.
Pure PVB is non-toxic and harmless to human body. In addition, ethyl acetate or alcohol can be used as solvent, so PVB is widely used in printing ink of food containers and plastic packaging in European and American countries.
Storage safety properties
PVB can be stored for two years without affecting its quality as long as it is not in direct contact with water; PVB shall be stored in a dry and cool place and avoid direct sunlight. Heavy pressure shall be avoided during PVB storage.
Solubility
PVB is soluble in alcohol, ketone, ester and other solvents. The solubility of various solvents changes according to the functional group composition of PVB itself. Generally speaking, alcohol solvents are soluble, but methanol is more insoluble for those with high acetal groups; The higher the acetal group, the easier it is to dissolve in ketone solvents and ester solvents;
PVB is easily soluble in cellosolve solvents; PVB is only partially dissolved in aromatic solvents such as xylene and toluene; PVB is insoluble in hydrocarbon solvents.
Viscosity characteristics of PVB solution
The viscosity of PVB solution is greatly affected by the formula of solvent and the type of solvent; Generally speaking, if alcohol is used as solvent, the higher the molecular weight of alcohol, the higher the viscosity of PVB solution;
Aromatic solvents such as xylene and toluene and hydrocarbon solvents can be used as diluents to reduce the viscosity of PVB solution; The effect of PVB chemical composition on viscosity is summarized as follows: under the same solvent and the same content of each base, the higher the degree of polymerization, the higher the solution viscosity; Under the same solvent and the same degree of polymerization, the higher the acetal group or acetate group, the lower the solution viscosity.
Dissolution method of PVB
Where mixed solvents are used, the dissolution step is to first put aromatic solvents (such as xylene, toluene, etc.) or ester solvents (such as n-butyl acetate, ethyl acetate, etc.) into the mixing, slowly put PVB into the mixing, and then add alcohol solvents (such as n-butanol, ethanol, etc.) after PVB is dispersed and expanded,
At this time, the dissolution time can be shortened by heating; Using this dissolution method, the formation of lumpy PVB can be avoided (because the dissolution time will be several times after the formation of lumpy PVB), so the dissolution speed can be accelerated. Generally, the ratio of aromatic and alcohol solvents is 60 / 40 ~ 40 / 60 (weight ratio), and PVB solution with low viscosity can be prepared.
The solvent composition contains 2 ~ 3wt% water, which can improve the hydrogen bonding strength of alcohol solvents and help the solubility of PVB.
Processing properties
Although PVB resin is a thermoplastic, it has little processability before plasticizer is added. Once plasticizer is added, its processability is very easy.
The purpose of general coatings and adhesives is to change the resin characteristics by adding plasticizers to meet the application requirements, such as film softness, reducing the TG point of the resin, reducing the heat sealing temperature, maintaining low-temperature softness, etc.
Compatibility
PVB can be compatible with a variety of resins, such as phenolic resin, epoxy resin, alkyd resin and MELAMINE resin.
B-08sy, b-06sy and b-05sy with high acetal degree can be mixed with nitrocellulose in any proportion. PVB and alkyd resin are partially compatible. General PVB is compatible with low molecular weight epoxy resin, while high molecular weight epoxy resin needs PVB with high acetal degree to be compatible with each other.
