In the crystalline state, pyrithione zinc (ZPT) exists as a centrosymmetric dime, where each zinc is bonded to two sulfur and three oxygen centers. The pyrithione ligands, formally monoanionic, are chelated to Zn2+ via oxygen and sulfur centers. In solution, however, the dimers dissociate via the scission of one Zn-O bond. Pyrithione is the conjugate base derived from 2-mercapto pyridine-N-oxide, a derivative of pyridine-N-oxide.
|pH Value (5% solution)||6.5-8.5|
|Drying Loss||0.5% Max.|
|Melting Point||240 deg. C Min.|
Pyrithione acts on bacterial cells. The bactericidal mechanism of zinc pyrithione varies slightly under different acidic and alkaline conditions.
Under neutral or acidic conditions, pyrithione takes K+ out of the bacterial cell and H+ into the bacterial cell. Under alkaline conditions, pyrithione takes K+ or Mg2+ out of the bacterial cell and Na+ into the bacterial cell.
By eliminating the ionic gradient for the bacteria to obtain nutrients, the cells are eventually “starved”. Therefore, the bactericidal mechanism of zinc pyrithione is not the same as that of many bactericides, as it kills bacteria without being consumed.
Method 1: The principle of preparation is that ZnSO4·7H2O reacts with SPT to produce ZPT and sodium sulfate.
Weigh the appropriate amount of zinc sulfate heptahydrate and prepare 0.25 mol/L and 0.50 mol/L of zinc sulfate solution, respectively. The sodium pyridine-thione solution was measured and designed as 0.5 mo l/L and 1.0 mol/L of sodium pyridine-thione solution, respectively. The reaction process conditions were controlled, and the two were quickly added into the three-necked flask separately in a certain volume ratio to obtain zinc pyrithione crystals, which were then filtered and washed. Vacuum-dried to obtain zinc pyrithione powder.
Method 2: Pyridine was used as raw material. After 30% H2O2 oxidation, N-oxidized-2-hydroxy pyridine was synthesized in dimethyl sulfoxide, toluene, and sulfur powder and combined with Zn2+ to form a salt. Although this method is simple, easy to obtain raw materials, and cheap, the yield is meager, only about 17%.
Method 3: Using 2-carboxy pyridine as raw material, the reaction conditions are relatively harsh, and catalysts such as NaH and LiCl are used in the reaction process, which is expensive and dangerous, making large-scale industrialization difficult.
Method 4: Using 2-chloropyridine as raw material, a catalytic oxidation system consisting of maleic anhydride and acetic acid was used. A Na2S-NaSH buffer system further controlled the sulfhydration reaction to obtain zinc pyrithione with a yield of about 75%.
Due to its low solubility in water (8 ppm at pH 7), zinc pyrithione (ZPT) is suitable for outdoor coatings and other products that protect against mold and algae. In addition, it is an effective algaecide. Zinc pyrithione can be compounded and applied to ship antifouling coatings to prevent marine life from adhering to the ship’s hull.
As an anti-mildew agent, zinc pyrithione also has some applications on fabrics. Therefore, zinc pyrithione on cotton and polyester/cotton fabrics was investigated under different mass concentrations, baking times, and temperatures.
The optimum process conditions were determined by single-factor and orthogonal tests. The process parameters of cotton fabrics were: zinc pyrithione mass concentration 0.04g/L, baking time 3min, baking temperature 120℃, 80% ginning rate, bath ratio 1:25; polyester/cotton fabrics were: zinc pyrithione mass concentration 0.03g/L, baking time 3min, baking temperature 130℃, 80% ginning rate, bath ratio 1:25. Zinc pyrithione anti-mildew agent can play the best anti-mildew effect.
Zinc pyrithione is chemically incompatible with paints that rely on metal carboxylate curing agents. When used in emulsion paints containing large amounts of iron in water, a chelating agent that preferentially binds iron ions is required. UV light slowly breaks down zinc pyrithione, providing years of protection even in direct sunlight.
In the pesticide field, zinc pyrithione is used mainly to control apple leaf curl and scab, among others.
Zinc pyrithione is used as an anti-dandruff agent and preservative in cosmetics and is widely used to prepare anti-dandruff shampoos. Zinc pyrithione is mainly used in cosmetics, shampoos, and skin care products.
Zinc pyrithione is widely used as a fungicide for paints and plastics. It has unique advantages in environmental friendliness and sterilization persistence. Therefore, it has a long-term application prospect in the future when emulsion paints are continuously environmentally friendly.
Packed in 25 kg or 250 kg net drums each and stored in tightly closed containers in a cool, dry area. Avoid light. Content is unchanged in two years.
Zinc pyrithione is safe when used as an anti-dandruff agent in rinse-off hair care products, and the concentration does not exceed 2%. Avoid contact with eyes and skin, and avoid inhalation of steam. Wash hands after use and prohibit eating or drinking in the workplace.
OM-1563, Zinc pyridine thioneone, de-squaman, N-HYDROXYPYRIDINETHIONE ZINC SALT, zincpolyanemine, bis(1-hydroxy-2-(1h)-pyridinethionato) zinc
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