Hydrotalcite increased initial whiteness calcium zinc stabilizers
Hydrotalcite (Hydrotalcite, HT) and the hydrotalcite compound (Hydrotalcite-likecompounds, HTlc) layer and a metal hydroxide is a layered double hydroxide interlayer charge-balancing anions with positive charge , also known as anionic clays .
Mostly natural hydrotalcite and hydrotalcite impurities . Are generally synthesized by chemical methods. Hydrotalcite can absorb acidic anions such as Cl-, sulfite ions to improve the thermal stability of the resin . But hydrotalcite as an application of PVC heat stabilizers found in Japan until 1980 Kyowa Chemical Company will hydrotalcite filled PVC heat stabilizers used as a patent . And developed a series of products Alkamizer grades .
Synthetic hydrotalcite and domestic research carried out in plastics applications late, Beijing University of Chemical Technology is a unit of the earliest to carry out the synthesis of hydrotalcite also studied some of the hydrotalcite modified plastics . China also has Dalian , Yixing industrialization several companies , but the market is not ideal . In response to this situation , from 2009 onwards,
Scott Plastics Ltd. Jingjiang Concord invested a lot of resources , human and financial resources, together with the EPRI study , followed by the world's advanced level , the development of a new generation of water talc products, and through high Technology means of modification. Hydrotalcite is a compound having a layered structure of hydrotalcite can be represented by the general formula [M2 +1- XM3 + X (OH) 2] X + [An-X / n? MH2O] X- wherein M2 + is a divalent metal cation , M3 + is a trivalent metal cation. An-is stable in an alkaline solution can be inorganic and organic anions , and different M2 + M3 +, between the different layers can form the anion An- type hydrotalcite. Common chemical composition included in the hydrotalcite atoms covalently bonded laminate (ionic bonding, hydrogen bonding ) connection and having exchangeable anions ( such as CO32-, Cl), which is the basic performance of the alkaline , special chemical composition and crystal structure, it has a unique , superior performance and effectiveness. When such materials can be effectively absorbed CO32- extrusion of PVC degradation HCl, HCl slow self catalytic PVC resin , an acid from an absorbent effect. Abroad is generally believed that the heat stability of hydrotalcite in the processing of PVC is due to absorption of the surface hydroxyl groups of the thermal degradation of PVC HCl gas , HCl to inhibit catalytic decomposition of PVC . Hydrotalcite in two steps reaction with HC1 : first, the interlayer anion HC1 reacts . Cl- between the intake layer , the purpose of absorbing the HC1 ; Then , hydrotalcite itself with HC1 column reaction layer structure is completely destroyed , the formation of metal chlorides , is absorbed HC1 gas . Thermal decomposition of hydrotalcite contains several stages, removal of crystal water at less than 200 ℃, at 250 ℃ ~ 450 ℃ Shelf hydroxyl dehydration and removal of carbon dioxide, magnesium aluminum composite gradually generate double metal oxide , at 450 ℃ ~ generate new phase , and gradually form a stable double metal oxide LDO, the temperature rises again would destroy its layered structure at 550 ℃ . Usually the PVC processing temperature does not exceed 250 ℃, so the process does not destroy the structure .
Therefore , compared with the conventional stabilizer. Hydrotalcite for Cl- capture capacity, avoid plastic yellow, and antioxidants such as BHT good compatibility , no corrosion, no acid gas , no more than Yi ; plastics can significantly improve weather resistance and heat resistance.
Concord special company producing high hydrotalcite is based on the original binary hydrotalcite on the introduction of organic ions of hydrotalcite intercalated supramolecular assembly , which increases the interlayer spacing hydrotalcite , reducing the shelf hydroxy force , making it easier to remove hydroxyl laminates , laminates effectively enhance the absorption of HCl , and can significantly improve the aging process PVC early color , so the initial whiteness calcium zinc stabilizers has been greatly increased.
Concact person :Willa shi
Mobile :86-13376005055
没有评论:
发表评论