Business Community, November 15th In the 30s of εthe 20th century, lead white<₹ ₹ was first successfully used i↓←πn the processing of PVC plastic pro∏ ✘ducts, and its thermal degradσ≥←ation problem was initially solved. Subsequen✘₹<tly, metal soaps, organotin compounds and other h¥©eat stabilizers have been reported one after£ another. In the 60s and 70↓s of the 20th century, a variety of new heat st≥≠ abilizers were developed, such as the succesγ↔sful development of food-grade octyltin ★€±heat stabilizer and the commercialization o¶f methyl tin. After the 80s o¶₽¶<f the 20th century, the technical progrδ>≈ess of heat stabilizers was re≈→£latively slow, but the research on environmental ∞σprotection was quite active, such as the OBS ££>organic stabilizer completed by Comp¥δ→™ton Company in United States in 2000, mainly™↔δ> used in hard products such as pipe↕♠€s.
At present, organotin stabilφσ☆izers are the main ones in North America, wδ€hile European countries are mainlyλ"™ calcium-zinc composite stabilizers, an≠&₽§d the tin content in plastic products is st≠σrictly limited (the allowable content is 0.002→↔mg/kg). However, due to the fact that organoti÷♣♥ n is a high-efficiency stabiliz★≥er, it is a transparent, non-toxic liquid, an©&∑λd the addition amount in PVC pipes♦ ✘✔ is only 0.25%-1.0%, so 20% of the st abilizer share in Europe is still oπ&♣rganotin stabilizer.
In the mid-50s of the 20th century×✔₹σ, with the localization of PVC production tec₽★♠•hnology, China began to produce heat stββabilizers, and the varieties at that time ★$£were only alkaline lead salts and stearic aci₽§↕βd soaps. In the early 60s of the 20th century,£✘∑ the production of heat stabilizers has bee®®☆♣n developed, the production t£÷echnology of general varieties has improved, and §β product quality testing and standardizati©≥"on have also begun to be emphasized. After d☆>βecades of development, research, productio☆•n and application, heat sta₹♣bilizers have developed into the second large←←st category of plastic additives, which can ε®&be divided into lead stabilizers,✘♦ calcium and zinc stabilizers, organotin stabiliz ★ers, auxiliary stabilizers and so ★♥•on according to their chemical composition and role.
Lead salt stabilizer is the he♥§ at stabilizer with the longest application hist" €&ory and good effect, and is widelε y used in PVC profiles, pipes, and insulated cabγβle materials. Basic lead salts are curreλ↑✔ntly the most widely used l§₩≥∑ead stabilizers. Lead stabilizerΩσ✘<s have good heat resistance, especially lon"→§αg-term thermal stability; Excellent electrical i γ nsulation; It has the performance of white pigme★÷nt, large covering power and good weath∞☆↑er resistance; It can be used as a§'n active agent for foaming agent and is inex↔δδpensive. The disadvantages of lead stab♠¥ilizers are: the resulting product is not trans☆↔♣parent; Highly toxic; There is initial cΩ↓olorability; Poor compatibility a ™↑nd dispersibility, easy to p✘roduce vulcanization pollution.
Calcium-zinc stabilizer is a non-toxic an✔≠<•d environmentally friendly heat stabiliz₩∑er with good lubricity, but its the≥✘≠rmal stability is not high, and it has been mostlλ'→y used in PVC soft products with low thermal ≥≥<stability requirements for a long time or< occasionally as an auxilia ♠ry heat stabilizer. In recent ye©®≥↔ars, with the development of organic auxi☆£liary additives such as β-dione, pol§∞σλyols, epoxy compounds, etc., calci≠←Ωum-zinc composite heat stabilizers have also €♠&been greatly developed. At present, a ££ variety of calcium-zinc composite hea∞t stabilizers with excellent pΩσ®erformance have been developed at ho★'★me and abroad, and are used in profiles, plat© ≈↕es and pipes.
Organotin compounds are highly effectiveק heat stabilizers, especially for hard produ≥§cts that require a high deg∞¶¶ree of transparency and high heat resis→₩tance. They often play the functions £•☆of photochemical, mechanical and bioc§™₽hemical stabilizers, plasticizers,↕α✔∑ etc., and are widely used and replac"→↕e other heat stabilizers, but their prices are h♣¥★igh, which limits their application to a ceπrtain extent, and people try to replace εother heat stabilizers with lowσ≤↔-cost tin to meet the needs of pri₩γce and performance.
Organic auxiliary heat stabilizers are also on♦™e of the current research directions.εσ× As early as 1940, derivatives of u∑∑↕rea such as diphenylthiourea and monophenylindo←βε≈le were recommended for stabilizing PVC. However§↓, due to various willingness, it ha↓✘s not been widely used. In rece•≠×nt years, due to the serious toxicity§¥ and pollution problems of £€metal stabilizers such as lead and cadmium, o≤♠©rganic stabilizers have attracted people&∞™#39;s attention again, and£≥ people hope to develop new varieties wit≠¶§≠h high efficiency and non-tox ™icity. Organic co-stabilizer ↔s do not have a thermal stabilizing effect↓× on their own, but they can iπ≥™mprove the performance of thermall→≥y stabilized systems. Belonging to→¶ this category are: organophσ₩↔•osphites, epoxy compounds, antioxidants, polyols ε↑±, etc.
In the past ten years, the consumption of heat st×φΩabilizers in China has increased s ☆φignificantly with the rapid develπφ✔opment of the PVC industry. According to '∑incomplete statistics, in 2008, the product struc•₽>ture of heat stabilizers in←☆φ• China was 40.0% lead salts,≠€•© 17.14% stearates, 27.43% composite ty ←pes (partially lead), 6.86% organotins, and 8.5♦©7% rare earth and others, as deta©♥∏iled in the following table:
In recent years, the output of heat sta±★π<bilizers in China has been 10,ε↑♣$000 tons
Note: In less than 20 years from '95 →$to 2000, production increased six-fold≥βφ€, which was about 700% of '95.•₽
There are hundreds of PVC stabilizer produc→↑¥tion plants in China, most of which are ∏located in Zhejiang, Shandong, Hebei, ★αJiangsu and Guangdong provinces. The ↑∏☆top 15 stabilizer manufacturers aα"∏ccount for more than 50% oβ≥'σf the market share, and 80% of them are &'"compound lead stabilizer m♣εanufacturers, and some of $γ♥≤the major suppliers are listed in the ch£βart below: