凌晨三点，PVC挤出线突然报警，出料从正常的乳白色变成焦黄色，机头压力飙升。当班班长紧急停机清模，拆开一看螺杆上挂满了降解的黑料。清理了两个多小时才重新开机，当晚产量少了三吨，第二天厂长在晨会上把班长骂到抬不起头——热稳定剂体系没选对，高温剪切下HCl没被及时吸收。
PVC在挤出机里一闹脾气就冒HCl，热稳定剂就是那个常年劝架的。
本文由长期经营塑料原料及助剂的宁波市科隆新材料有限公司整理，牌号与批次信息以实际供货渠道为准。
热稳定剂速查总表：四大体系各守各的温度区间
热稳定剂不是一种东西，而是按环保等级和透明要求分成几个阵营：铅盐便宜稳定但不环保，钙锌无毒透明，有机锡透明性好但贵，钡锌做过渡。先看这张表，把各自的“地盘”搞清楚，再选不迟。
| 体系 | 代表品种 | 关键特点 | 典型制品 | 用量(份/100树脂) |
|---|
| 铅盐类 | 三盐/二盐、复合铅盐 | 便宜、热稳定强、不透明 | 型材、管材、电缆料 | 3-6 |
| 钙锌类 | 钙锌复合稳定剂 | 无毒、透明、环保 | 软管、食品接触、透明件 | 2-5 |
| 有机锡类 | 甲基锡/丁基锡 | 透明性出色、耐候 | 透明片材、软质透明品 | 1.5-3 |
| 钡锌类 | 钡锌复合 | 过渡型、性价比 | 一般软制品、薄膜 | 2-4 |
注：表中数据为通用参考，不同体系热稳定时间差异较大，以各厂商官方TDS和实测数据为准。PVC用量以100份树脂为基准（份），与其他品类按百分比添加不同，这点别换算错。
图1 热稳定剂——PVC熔融加工的稳定核心
热稳定剂不是加够就行，是得选对它守的那段温度
先认识下这位PVC加工线上的“定海神针”。宁波市科隆新材料有限公司长期经营各类塑料助剂及改性原料，覆盖国内外多个品牌货源，在PVC热稳定剂、润滑剂、加工助剂等品类上有稳定供货渠道。而热稳定剂这个品类，是PVC加工的“定海神针”——PVC分子里的氯原子对热很敏感，加工温度一旦到160到200℃，就容易脱氯化氢，引发连锁降解，表现为变色、力学性能下降直至碳化。热稳定剂的作用有三：吸收中和放出的HCl、置换不稳定的氯原子、捕捉自由基打断链式反应。
热稳定剂就是PVC的灭火器，加工那几分钟先把自由基的火按住。
不同体系守的温度区间和“脾气”不一样。铅盐类热稳定性强、成本低，但含铅、不透明，多用于不透明的型材、管材，出口和食品场景基本被淘汰；钙锌类无毒环保、可透明，是当前替代铅盐的主流，缺点是初期着色和长期透明性要调配方；有机锡类透明性、耐候性出色，做高透明片材、食品级制品，但价格高；钡锌类定位过渡，性价比折中。选稳定剂，本质是在环保等级、透明性和成本之间找平衡。
把HCl这根导火索剪断，PVC才能在180℃的锅里待得住。
很多新手以为稳定剂加得越多越稳，其实不然。过量的热稳定剂会从制品内部迁移到表面，形成“喷霜”或析出白雾，粘模、影响印刷和焊接；钙锌、有机锡超量还可能起雾、影响透光。所以行业里讲“够用就好”，不是偷工减料，而是守住析出红线。
还在用铅盐做透明食品片材？这不是省钱，这是在给客户埋雷。
逐品种速查：铅盐守型材，钙锌管环保，有机锡守透明
热稳定的牌号杂，但抓住四大阵营的主力，就能覆盖八成PVC加工。下面逐个讲定位、适用信号和注意事项。
型材上铅盐、软管换钙锌、透明片找有机锡，别一张配方打天下。
复合铅盐稳定剂：把三盐基硫酸铅、二盐等复配并预混好，热稳定效率高、价格友好，是传统型材、管材、电缆料的主力。选它的信号：做不透明PVC型材/管材、对成本敏感、内销非食品。注意：含铅，出口欧盟和食品接触场景禁用，环保压力大的地区正在被钙锌替代。
供货提示：钙锌和有机锡热稳定剂科隆新材均有稳定货源，每批附热稳定性测试数据（刚果红时间），公斤级试样可先做挤出验证。
钙锌复合稳定剂：以钙皂、锌皂为主复配辅助剂，无毒、环保、可做透明，是铅盐替代的主流方向。选它的信号：做PVC软管、透明软制品、食品接触、出口欧盟料。注意：钙锌初期易着色（“锌烧”风险），长期热稳定和透明保持需要配方工程师仔细调，初期着色偏黄要靠辅助剂压。
有机锡稳定剂（甲基锡、丁基锡）：透明性和耐候性出色，做高透明PVC片材、饮料瓶、食品包装。选它的信号：做高透明制品、要求高透光率和低析出。注意：有机锡价格高，部分辛基锡类涉及法规限制，食品接触要选合规牌号。
H一跑出来就是多米诺的头一张牌，热稳定剂把它按住，后面就不会骨牌全倒。
钡锌复合稳定剂：过渡型方案，性能介于铅盐和钙锌之间，性价比折中，用于一般软制品、农用薄膜。选它的信号：对透明和环保要求中等、成本敏感。注意：环保趋严下钡锌也在逐步被钙锌取代。
辅助协同：实际配方里，主稳定剂常配润滑剂（硬脂酸钙、PE蜡）和抗氧剂一起用，形成“稳定+润滑+抗氧”的组合，而不是单靠一种稳定剂硬撑。
替代对照：铅盐换钙锌、进口换国产，怎么换才稳
这几年PVC环保升级，最多的两件事就是铅盐换钙锌、进口稳定剂换国产。替代不是把料一换就行，热稳定体系一动，塑化行为、析出、初期着色全跟着变。下面这张表列常见替代方向和切换前提。
| 原用方向 | 典型应用 | 可对标方案 | 切换前提 |
|---|
| 复合铅盐稳定剂 | PVC型材/管材 | 钙锌复合稳定剂 | 对比初期着色、动态热稳定时间、析出量 |
| 进口有机锡 | 高透明片材/食品 | 国产有机锡 | 对比透光率、雾度、食品合规迁移量 |
| 进口钙锌稳定剂 | 环保软制品 | 国产钙锌复配 | 对比锌烧倾向、长期热稳定、析出 |
| 钡锌稳定剂 | 一般软制品 | 钙锌稳定剂 | 对比成本、透明度、加工窗口 |
表中列的是切换思路，具体到批次仍要自己跑数据。切换要重新标定加工温度和螺杆工艺，因为钙锌的塑化行为和铅盐不同。
热稳定剂换体系要上机验证，科隆新材可按公斤级寄送钙锌或有机锡试样，随附刚果红热稳定时间数据，客户先在挤出线上跑小批量再决定是否切换。
出料就发黄？先查热稳定剂够不够、热剪切狠不狠，别急着怪树脂。
行业场景速查：不同PVC制品对稳定剂的要求差在哪
同样是热稳定剂，做塑钢型材和做食品保鲜膜，环保和透明要求完全不同。下面这张表按行业拆解。
| 行业 | 典型制品 | 客户先问的参数 | 推荐体系 | 认证要求 |
|---|
| 建材 | 塑钢型材、门窗 | 长期户外耐候、析出 | 复合铅盐或钙锌 | GB建材、RoHS |
| 管材 | 给水管、穿线管 | 卫生性能、热稳定 | 钙锌/有机锡 | 饮用水GB标准 |
| 软制品 | 软管、电缆料 | 无毒、低析出 | 钙锌 | REACH、RoHS |
| 透明包装 | 透明片材、吸塑盒 | 透光率、雾度 | 有机锡 | 食品GB 4806 |
| 玩具/日用品 | PVC玩具、文具 | 无毒环保 | 钙锌 | 玩具GB 6675、欧盟 |
举个具体场景：做PVC给水管，客户要求符合饮用水卫生标准、动态热稳定时间够长、长期不析出。这时铅盐直接出局，得用钙锌或有机锡，同时控制润滑剂析出，避免影响水味和内壁光洁。
添加量与搭配要点：四个配方思路记住就够了
PVC热稳定用量按“份”计，不是百分比，这是和其他品类最大的不同。下面四个思路覆盖主流场景。
热稳定剂这东西，加够是保平安，加多是找麻烦，析出喷霜从不跟你讲情面。
◆ 不透明型材/管材：复合铅盐（3-6份）+ 润滑剂，成本优先，内销非环保项目。
◆ 环保软制品/软管：钙锌复合（2-5份）+ 润滑剂，主打无毒可出口。
◆ 高透明片材：有机锡（1.5-3份）+ 透明级润滑，控透光率和雾度。
◆ 通用软膜：钡锌或钙锌（2-4份），性价比折中，注意环保趋势。
此外还有三条经验值得记：一是热稳定剂要和润滑剂（硬脂酸、PE蜡、硬脂酸钙）一起调，稳定剂管“不分解”，润滑剂管“好加工”，缺一个都不顺；二是钙锌要防“锌烧”，初期着色严重时需补辅助剂，别盲目加量；三是环保法规趋严，含铅、含锡的合规牌号逐年收紧，出口料要提前确认法规版本。
环保大潮下铅盐退场不是喊口号，出口欧盟的料铅盐基本没戏。
PVC：稳字当头。
加工与合规红线：这五个坑别踩
PVC加工翻车，八成和热稳定没配好有关。下面这张表把关键环节列清楚。
| 环节 | 参考值 | 做错的后果 |
|---|
| 加工温度 | 硬PVC 160-190℃，软PVC更低 | 超温停留→快速分解、黄变碳化 |
| 热稳定用量 | 主稳定剂3-8份/100树脂 | 不足→加工即变色；过量→析出喷霜 |
| 塑化与停留 | 控制螺杆停留，避免死角积料 | 积料碳化→制品黑点、杂质 |
| 钙锌防锌烧 | 初期着色时补辅助剂 | 盲目加量→透明性下降 |
| 环保合规 | 出口选钙锌/合规有机锡 | 用错含铅体系→整批退货 |
合规红线：饮用水、食品接触制品必须符合相应国标和食品迁移测试；出口欧盟关注REACH限制物质和玩具指令；含铅、特定有机锡在多个法规下受限。切换前务必把法规清单和供应商合规文件核对清楚。
FAQ：采购与配方师常问的六个问题
Q1：国产热稳定剂能不能替代进口料？
可以，但要分体系。通用型材、管材用的复合铅盐和普通钙锌，国产品牌差距已经很小；高透明有机锡、食品级钙锌在透明保持和批次一致性上，进口仍有优势。替代的正确做法是拿公斤级样品做动态热稳定对比，看初期着色、长期热稳定时间和析出，通过后再小批量放量。需要上机对照的样品，科隆新材可按公斤级安排，随附刚果红热稳定时间数据。
Q2：PVC一开机就发黄，是什么原因？
先查三点：热稳定剂用量够不够、有没有按份数算错；加工温度是不是偏高、物料在螺杆里停留太久积料；钙锌体系是不是出现初期着色（锌烧），需要补辅助剂。都排除再看树脂本身热稳定性。
Q3：为什么PVC用量用“份”而不是百分比？
因为PVC配方是“以100份树脂为基准”的体系，增塑剂、稳定剂、填料都按相对树脂的份数加，这是行业传统习惯。换算时要先锁定树脂用量，别和按成品百分比的助剂搞混。
Q4：铅盐为什么要被钙锌替代？
铅盐虽热稳定好、便宜，但含铅有毒，环保和出口法规限制越来越严。钙锌无毒环保、可做透明，是政策和市场双重推动下的主流替代方向，只是初期着色和成本还需要配方优化。
Q5：热稳定剂加多了有什么坏处？
析出喷霜：过量稳定剂迁移到表面，形成白雾或粉末，粘模、影响印刷和焊接；透明件还会起雾、透光率下降。所以够用就好，不是越多越稳。
Q6：有机锡为什么这么贵，值得吗？
有机锡贵在透明性和耐候性，高透明片材、食品包装确实离不开它；如果是不透明型材，用铅盐或钙锌就够了，没必要上有机锡。按需选用，别为用不上的性能买单。
选型三步清单：照着做不踩坑
◆ 第1步·定合规等级：先明确制品是否食品接触、是否出口、是否要求透明，据此圈定可用体系（铅盐/钙锌/有机锡/钡锌）。
◆ 第2步·算用量配润滑：按100份树脂定稳定剂用量3-8份，配合润滑剂和抗氧剂，做动态热稳定试验验证加工窗口。
◆ 第3步·核法规文件：按用途核对饮用水、食品、玩具、REACH等法规，向供应商索取合规文件与批次报告归档。
PVC稳不稳，挤出机最诚实
热稳定剂的选型和PVC制品的出口目的地强相关——做欧盟订单基本不能用铅盐，做透明片材优选有机锡，做通用型材钙锌性价比高。科隆新材可根据客户的制品类型和合规要求推荐热稳定体系，随货附刚果红热稳定时间和挥发分检测数据，试样按公斤级提供，先上机试再定批量。
前年，一家做PVC型材的厂接到一笔欧盟订单，原来的铅盐体系过不了REACH，急得团团转。科隆新材给他们推荐了钙锌复合稳定剂，寄了公斤级试样。客户上机试了三天，前两批出料偏黄，调整了润滑体系后第三批稳定通过。最终整批货顺利出口，厂长说原以为换体系要停线半个月，没想到一周就跑顺了。
出料发黄那天，你先查料还是查热稳定剂？
声明：本文涉及的品牌、商标及产品名称权归各自原厂所有。本文为第三方选材知识分享，文中提及的牌号、参数、价格、认证及应用案例仅供参考，具体以各生产企业官方最新资料及批次检测报告为准。本文不构成任何采购或投资建议，读者据此操作风险自担。
At three o’clock in the morning, the PVC extrusion line suddenly went into alarm. The output material changed from the usual milky white to burnt yellow, and the head pressure soared. The shift supervisor urgently stopped the machine to clean the mold. Upon opening it, they found the screw covered with degraded black material. After more than two hours of cleaning, the machine was restarted. That night, production was down by three tons. The next day, the plant manager scolded the supervisor so badly at the morning meeting that he couldn’t lift his head—the heat stabilizer system was not chosen correctly, and under high-temperature shear, HCl was not absorbed in time.
When PVC throws a tantrum in the extruder, it releases HCl, and the heat stabilizer is like the one constantly trying to mediate.
This article is compiled by Ningbo Kolong New Materials Co., Ltd., which has long been engaged in the business of plastic raw materials and additives. The grade and batch information are subject to the actual supply channels.
Quick Reference Table of Heat Stabilizers: Each of the Four Major Systems Maintains Its Own Temperature Range
Heat stabilizers are not a single thing; they are divided into several camps according to environmental protection level and transparency requirements: lead salts are cheap and stable but not environmentally friendly, calcium-zinc is non-toxic and transparent, organic tin has good transparency but is expensive, and barium-zinc acts as a transition. First, look at this table to understand each one’s 'territory,' and then it’s not too late to choose.
| system | Representative variety | Key Features | Typical products | Dosage (parts/100 resin) |
|---|
| Lead salts | Tribasic/ Dibasic, Compound Lead Salts | Cheap, thermally stable, opaque | Profiles, pipes, and cable materials | 3-6 |
| Calcium and zinc types | Calcium-zinc compound stabilizer | Non-toxic, transparent, environmentally friendly | Hoses, food contact, transparent parts | 2-5 |
| Organotin compounds | Methyl tin / Butyl tin | Excellent transparency, weather-resistant | Transparent sheets, soft transparent products | 1.5-3 |
| Barium-zinc type | Barium zinc composite | Transitional type, cost-performance ratio | General soft products, films | 2-4 |
Note: The data in the table is for general reference. The thermal stability time varies greatly among different systems, and the official TDS and actual test data of each manufacturer should prevail. The PVC dosage is based on 100 parts of resin (parts), and it is added differently from other categories based on percentage, so do not miscalculate this.
Figure 1 Thermal Stabilizers—The Core of PVC Melt Processing Stability
Heat stabilizers aren't just about adding enough; you have to choose the one suitable for the temperature range it can withstand.
Let's first get to know the 'steadying force' on this PVC processing line. Ningbo Kolon New Materials Co., Ltd. has long been engaged in various plastic additives and modified raw materials, covering multiple domestic and international brands, and has stable supply channels for PVC heat stabilizers, lubricants, and processing aids. The heat stabilizer category is the 'steadying force' of PVC processing—chlorine atoms in PVC molecules are very sensitive to heat, and once the processing temperature reaches 160 to 200°C, they easily release hydrogen chloride, triggering chain degradation, which manifests as discoloration, decline in mechanical properties, and even carbonization. The role of heat stabilizers includes three aspects: absorbing and neutralizing released HCl, replacing unstable chlorine atoms, and capturing free radicals to interrupt chain reactions.
A heat stabilizer is like a fire extinguisher for PVC, suppressing the flames of free radicals during the few minutes of processing.
Different systems have different temperature ranges and 'temperaments.' Lead-based stabilizers have strong thermal stability and low cost, but contain lead and are opaque, mostly used in opaque profiles and pipes, and have basically been phased out for export and food applications. Calcium-zinc stabilizers are non-toxic, environmentally friendly, and can be transparent; they are the current mainstream substitute for lead-based stabilizers, but the drawbacks are initial coloration and the need to adjust formulations for long-term transparency. Organic tin stabilizers have excellent transparency and weather resistance, suitable for high-transparent sheets and food-grade products, but are expensive. Barium-zinc stabilizers are positioned as a transitional option, offering a compromise in cost-performance. Choosing a stabilizer essentially involves finding a balance among environmental standards, transparency, and cost.
Only by cutting this fuse of HCl can PVC stay in a pot at 180°C.
Many beginners think that the more stabilizer is added, the more stable it will be, but this is not the case. Excess thermal stabilizer can migrate from the interior of the product to the surface, forming 'blooming' or white haze, causing sticking to molds and affecting printing and welding; excessive calcium-zinc and organic tin can also cause haze and affect transparency. Therefore, in the industry, they say 'use only as much as needed,' which is not cutting corners, but staying within the safety limit for precipitation.
Still using lead salts to make transparent food sheets? This isn't saving money, it's planting landmines for your customers.
Quick reference by type: lead-salt stabilized profiles, calcium-zinc pipes environmentally friendly, organic tin stabilized transparent
The grades are mixed in terms of heat stability, but by focusing on the main forces of the four major camps, you can cover 80% of PVC processing. Below, we discuss the positioning, applicable signals, and precautions one by one.
Apply lead salts on the profiles, replace calcium-zinc in the hoses, check for organotin in the transparent sheets, don’t rely on one formula for everything.
Compound lead salt stabilizer: A premixed blend of tribasic lead sulfate, dibasic lead, etc., with high thermal stability efficiency and cost-friendliness, is the main choice for traditional profiles, pipes, and cable materials. Signals to choose this: making opaque PVC profiles/pipes, cost-sensitive, domestic non-food applications. Note: Contains lead, prohibited for export to the EU and for food contact applications, and is being replaced by calcium-zinc in areas with high environmental pressure.
Supply Note: Calcium-zinc and organic tin heat stabilizers are all stably supplied by Cologne New Materials, with each batch accompanied by heat stability test data (Congo red time). Kilogram-scale samples can first be used for extrusion verification.
Calcium-zinc composite stabilizer: primarily composed of calcium soap and zinc soap, mixed with auxiliary agents. It is non-toxic, environmentally friendly, and can be made transparent. This is the mainstream direction for substituting lead salts. Signals for choosing it: used for PVC hoses, transparent soft products, food contact, and exports to EU materials. Note: Calcium-zinc can easily discolor initially (risk of 'zinc burn'), and long-term heat stability and transparency maintenance require careful formulation by engineers. Initial yellowish discoloration needs to be suppressed with auxiliary agents.
Organic tin stabilizers (methyl tin, butyl tin): Excellent transparency and weather resistance, used for high-transparency PVC sheets, beverage bottles, and food packaging. Signals for choosing it: making high-transparency products, requiring high light transmittance and low migration. Note: Organic tin is expensive, some octyl tin types are subject to regulatory restrictions, and food contact applications should choose compliant grades.
As soon as H comes out, it's the first card of the dominoes. The thermal stabilizer holds it in place so that the rest won't all fall like dominoes.
Barium-zinc composite stabilizer: transitional type, performance between lead salts and calcium-zinc, cost-performance compromise, used for general soft products and agricultural films. Signals for choosing it: moderate requirements for transparency and environmental protection, cost-sensitive. Note: under stricter environmental regulations, barium-zinc is also gradually being replaced by calcium-zinc.
Auxiliary synergy: In actual formulations, the main stabilizer is often used together with lubricants (calcium stearate, PE wax) and antioxidants to form a combination of 'stabilization, lubrication, and antioxidation,' rather than relying on a single stabilizer alone.
Alternative comparison: Replacing lead salts with calcium and zinc, switching from imported to domestic products—how to make the change stable
In recent years, PVC environmental upgrades have mainly involved two things: replacing lead salts with calcium-zinc, and replacing imported stabilizers with domestic ones. Replacement is not just a simple material swap; once the thermal stabilization system changes, plasticizing behavior, blooming, and initial coloration all change accordingly. The table below lists common replacement directions and the prerequisites for switching.
| Original direction | Typical Applications | Benchmark solution | Switch premise |
|---|
| Composite lead salt stabilizer | PVC profiles/pipes | Calcium-zinc compound stabilizer | Compare initial coloring, dynamic thermal stability time, and precipitation amount |
| Imported Organotin | High transparency sheet / Food | Domestic Organotin | Compare light transmittance, haze, and food compliance migration levels |
| Imported calcium-zinc stabilizer | Eco-friendly soft products | Domestic calcium-zinc compound | Comparison of zinc roasting tendency, long-term thermal stability, and precipitation |
| Barium zinc stabilizer | General soft products | Calcium-zinc stabilizer | Compare cost, transparency, and processing window |
The table lists switching ideas, but for specific batches you still need to run your own data. Switching requires recalibrating the processing temperature and screw process, because the plasticizing behavior of calcium-zinc is different from that of lead salts.
When changing the system of heat stabilizers, machine verification is required. Cologne New Materials can send calcium-zinc or organic tin samples by kilogram, accompanied by Congo red heat stabilization time data. The customer will first run a small batch on the extrusion line before deciding whether to switch.
Does it turn yellow as soon as it's discharged? First check if there is enough heat stabilizer and whether the thermal shear is harsh, don't rush to blame the resin.
Industry Scenario Quick Reference: How the Requirements for Stabilizers Differ Among Various PVC Products
Although both are heat stabilizers, the requirements for environmental friendliness and transparency are completely different when making plastic steel profiles and food preservation films. The table below breaks it down by industry.
| Industry | Typical products | The parameters the client asked about first | Recommendation system | Certification requirements |
|---|
| building materials | Plastic steel profiles, doors and windows | Long-term outdoor weather resistance and precipitation | Compound lead salts or calcium zinc | GB Building Materials, RoHS |
| Pipe material | Water pipes, conduit pipes | Hygienic performance, thermal stability | Calcium zinc/organic tin | Drinking Water GB Standard |
| Soft goods | Hose and cable materials | Non-toxic, low leaching | Calcium and zinc | REACH, RoHS |
| Transparent packaging | Transparent sheets, blister boxes | Light transmittance, haze | Organotin | Food GB 4806 |
| Toys / Daily Necessities | PVC toys, stationery | Non-toxic and environmentally friendly | Calcium and zinc | Toy GB 6675, European Union |
A specific scenario: producing PVC water supply pipes, where the customer requires compliance with drinking water hygiene standards, sufficient dynamic heat stability time, and no long-term leaching. In this case, lead salts are immediately ruled out, and calcium-zinc or organotin must be used, while also controlling the leaching of lubricants to avoid affecting the water taste and the smoothness of the inner wall.
Dosage and matching points: Remembering four formula ideas is enough
The dosage of PVC heat stabilizers is measured in 'parts,' not percentages. This is the biggest difference compared to other categories. The following four approaches cover the main scenarios.
Heat stabilizers, when added enough, ensure safety; when added too much, they cause trouble. Precipitation and frosting never show you any mercy.
◆ Opaque profiles/pipes: composite lead salts (3-6 parts), lubricant, cost-priority, domestic non-environmental projects.
◆ Environmentally friendly soft products/hoses: Calcium-zinc compound (2-5 parts) lubricant, mainly non-toxic and exportable.
◆ High transparency sheet: Organotin (1.5-3 parts) Transparent grade lubrication, controls light transmittance and haze.
◆ General flexible membrane: Barium zinc or calcium zinc (2-4 parts), cost-performance balanced, pay attention to environmental protection trends.
In addition, there are three pieces of experience worth noting: first, the heat stabilizer should be adjusted together with the lubricant (stearic acid, PE wax, calcium stearate); the stabilizer ensures 'no decomposition,' and the lubricant ensures 'good processability'; lacking either one will cause issues. Second, with calcium-zinc stabilizers, beware of 'zinc burning'; if severe initial coloring occurs, supplements are needed, but do not blindly increase the amount. Third, environmental regulations are becoming stricter, and the compliance grades containing lead and tin are tightening year by year; for export materials, regulations versions need to be confirmed in advance.
Under the wave of environmental protection, phasing out lead salts is not just a slogan; materials exported to the EU basically have no chance of containing lead salts.
PVC: Stability comes first.
Processing and Compliance Red Lines: Avoid These Five Pitfalls
PVC processing accidents are eighty percent related to improper heat stabilization. The table below clearly lists the key steps.
| link; segment; part | Reference value | The consequences of doing wrong |
|---|
| Processing temperature | Rigid PVC 160-190°C, soft PVC even lower | Overtemperature stay → rapid decomposition, yellowing, carbonization |
| Heat-stable dosage | Main stabilizer 3-8 parts/100 resin | Insufficient → discolors immediately upon processing; Excess → precipitates and frosts |
| Plasticization and Retention | Control the screw to stay in place to avoid material accumulation in dead corners | Material accumulation carbonization → product black spots, impurities |
| Calcium-zinc prevents zinc burn | Add auxiliary agents during initial coloring | Blindly increasing the dosage → decreased transparency |
| Environmental compliance | Export selected calcium zinc / compliant organic tin | Used the wrong lead-containing system → return the entire batch |
Compliance Red Lines: Drinking water and food contact products must comply with the relevant national standards and food migration tests; exports to the EU should pay attention to REACH restricted substances and the Toy Directive; lead and certain organotin compounds are restricted under multiple regulations. Before switching, be sure to check the list of regulations and supplier compliance documents carefully.
FAQ: Six Common Questions from Buyers and Formula Chemists
Q1: Can domestic thermal stabilizers replace imported materials?
Yes, but it should be divided by system. For general profiles and pipes, the gap between domestic brands and imported brands for composite lead salts and ordinary calcium-zinc is already very small; for high-transparency organotin and food-grade calcium-zinc, imports still have an advantage in transparency maintenance and batch consistency. The correct approach for substitution is to use kilogram-level samples for dynamic heat stability comparison, checking initial coloration, long-term heat stability time, and precipitation. After passing, then gradually increase the quantity in small batches. For samples that need to be tested on machines, Cologne New Materials can arrange kilogram-level quantities, accompanied by Congo red heat stability time data.
Q2: Why does PVC turn yellow as soon as it is powered on?
First, check three points: whether the amount of heat stabilizer is sufficient, and whether there was a miscalculation in the dosage; whether the processing temperature is too high, causing the material to stay too long in the screw and accumulate; whether the calcium-zinc system shows initial discoloration (zinc burning), requiring additional auxiliary agents. After ruling these out, then look at the thermal stability of the resin itself.
Q3: Why is the amount of PVC measured in 'parts' rather than in percentage?
Because the PVC formulation is a system based on '100 parts of resin,' plasticizers, stabilizers, and fillers are added according to the parts relative to the resin. This is the traditional industry practice. When converting, the resin amount must be fixed first, so as not to confuse it with additives calculated as a percentage of the finished product.
Q4: Why should lead salts be replaced by calcium and zinc?
Although lead salts are thermally stable and inexpensive, they contain toxic lead, and environmental protection and export regulations are becoming increasingly strict. Calcium-zinc is non-toxic and environmentally friendly, and can be made transparent. It is the mainstream alternative direction driven by both policy and market, but initial coloring and costs still require formulation optimization.
Q5: What are the disadvantages of adding too much heat stabilizer?
Blooming of stabilizer: Excess stabilizer migrates to the surface, forming a white haze or powder, causing mold sticking, affecting printing and welding; transparent parts may also haze and their light transmittance decreases. So use just enough — more is not necessarily more stable.
Q6: Why is organotin so expensive? Is it worth it?
Organotin is expensive because of its transparency and weather resistance. It is indispensable for high-transparency sheets and food packaging; for opaque profiles, lead salts or calcium-zinc stabilizers are enough, and there is no need to use organotin. Choose based on needs; don’t pay for performance you don’t require.
Three-step selection checklist: Follow to avoid pitfalls
◆ Step 1 · Determine compliance grade: First clarify whether the product comes into contact with food, is for export, or requires transparency, then narrow down the applicable system (lead salt / calcium-zinc / organotin / barium-zinc).
◆ Step 2 · Calculate dosage and add lubricants: For every 100 parts resin, use 3–8 parts stabilizer, combined with lubricants and antioxidants, then conduct a dynamic thermal stability test to verify the processing window.
◆ Step 3 · Verify regulatory documents: Check regulations such as drinking water, food, toys, REACH according to the application, obtain compliance documents and batch reports from suppliers for archiving.
Whether PVC is stable, the extruder speaks the truth
The choice of thermal stabilizer is closely related to the export destination of PVC products — such as European orders basically cannot use lead salts, transparent sheets preferably use organotin, and calcium-zinc is cost-effective for general profiles. Kolon New Materials can recommend stabilizer systems based on the type of product and compliance requirements, provide Congo Red thermal stability times and volatile content data with shipments, and provide kilogram-level samples for trial processing before confirming large-scale production.
Two years ago, a PVC profile manufacturer received an EU order. Their original lead salt system did not meet REACH, causing considerable stress. Kolon New Materials recommended a calcium-zinc composite stabilizer and sent kilogram-level samples. The customer trialed it on the extruder for three days; the first two batches were slightly yellow, and after adjusting the lubricant system, the third batch stabilized successfully. The entire shipment was finally exported smoothly. The factory manager said they expected a half-month shutdown for the system change, but surprisingly it only took a week.
On the day the extrudate turns yellow, would you first check the raw material or the stabilizer?
Disclaimer: The brands, trademarks, and product names mentioned in this article are the property of their respective owners. This article is a third-party material selection knowledge sharing. The grades, parameters, prices, certifications, and application cases mentioned are for reference only; the specifics should be based on the manufacturers’ official latest information and batch test reports. This article does not constitute any purchasing or investment advice, and readers assume any risks based on their own actions.
