一批EVA鞋底发完泡，一只轻一只重，泡孔大的大小的小，品牌方抽检不合格，整批约五万双鞋被扣在仓库里。配方师查了半天，AC发泡剂分解温度偏高，氧化锌发泡助剂只加了0.1份，分解不均匀，等于酵母没发匀，面包就有了大有小。
从车间上空往下看，每一块发泡塑料里都藏着上亿个小气泡——减重、隔热、缓冲，全靠它们。
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。
发泡剂速查总表：化学发、物理发、微珠发三条路
发泡剂不是一种东西，而是三条技术路线：靠化学分解产气、靠物理气体注入、靠预置空心微珠。选哪条，取决于你要多重、多薄、耐不耐温，以及设备改不改得起。下面这张表把主流体系一页列清。
| 体系 | 代表品种 | 关键参数 | 典型制品 | 添加比例 |
|---|
| 化学放热型 | AC偶氮二甲酰胺 | 分解温度180-220℃，需ZnO/硬脂酸锌助发泡 | EVA鞋材、PVC/PP发泡件 | 0.3%-1% |
| 化学吸热型 | 碳酸氢钠/柠檬酸复配 | 分气温和、吸热、温度低 | 食品包装片材、PE发泡 | 0.5%-2% |
| 物理发泡 | 超临界CO₂、丁烷、氮气 | 高压注入熔体，微孔均匀 | XPS保温板、汽车微发泡内饰 | 气体0.5%-5% |
| 空心微珠 | 玻璃微珠、陶瓷微珠 | 物理填充减重，不产气 | SMC、人造石、配重料 | 5%-20%(体积) |
注：表中分解温度和发气量为通用参数，实际发泡倍率受工艺影响，以官方TDS为准。先定目标密度和壁厚，再选路线，别上来就谈牌号。
图1 发泡剂——塑料熔体里的微孔蜂窝结构
发泡剂是塑料的酵母，会发还要会稳
这位主角，是塑料的酵母。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，在发泡剂、阻燃剂、着色剂等常用助剂品类上有稳定供货渠道。发泡剂这个品类，本质上就是塑料的“酵母”——面团靠酵母撑起蜂窝，塑料靠发泡剂撑起泡孔，体积膨胀、密度下降，重量和成本一起往下走。
发泡剂对塑料就像酵母对面团——一点点发起来，体积翻几倍，密度却掉下来。
主流机理分两类。化学发泡剂受热分解释放气体（氮气、二氧化碳等），在熔体中成核、长大，冷却定型后把气泡锁住。AC是典型的放热型，产气量大、分解温度偏高，必须配发泡助剂把分解温度拉进加工窗口；碳酸氢钠是吸热型，产气温和、不额外升温，适合薄壁和食品级制品。物理发泡则直接把超临界二氧化碳或丁烷高压注入熔体，气体在高压下溶解，卸压瞬间成核，能做出更均匀的微孔。
AC是个脾气倔强的酵母，不拿氧化锌哄着，它绝不肯在鞋材要的温度里乖乖发面。
泡孔质量其实是三件事：成核要均匀、长大要受控、冷却要及时锁住。温度太低，气没发起来；温度太高，泡孔合并、塌泡、表面银纹。所以行业里常说：发泡这事，会发只是入门，发得稳才是真功夫。
发泡剂的KPI就一条：该发的时候发，不该发的时候别乱发。
逐品种速查：AC是鞋材主力，碳酸氢钠走温和路，超临界CO₂做微孔
品种看着杂，抓住几条主线就能盖大部分应用。
猛火配小火，泡孔才不偏心——单一发泡剂就像一把刀切所有料，迟早要塌。
AC偶氮二甲酰胺：化学放热型发泡剂的主力，发气量大、性价比高，EVA鞋材、PVC发泡件里用得最多。选它的信号：做鞋材中底、发泡拖鞋、PP/PVC结皮发泡板。注意：分解温度180-220℃偏高，必须配发泡助剂；分解残留有轻微气味和黄变倾向，浅色和食品级要谨慎。
供货提示：AC发泡剂和发泡助剂科隆新材可配套供货，每批附分解温度和发气量数据，公斤级试样支持先做发泡倍率对比。
发泡助剂（氧化锌、硬脂酸锌等）：本身不产气，作用是降低AC的分解温度、让产气曲线更平缓。配0.1%-0.3%就能把AC分解温度从200℃拉到160℃上下，是鞋材配方里和AC绑定的搭档。注意：加太多会黄变、影响白度。
碳酸氢钠/柠檬酸复配：吸热型发泡剂，分解温度低、产气温和、不升温，残留在食品级场景更友好。选它的信号：做PE食品包装片材、薄壁发泡、对气味和黄变敏感的浅色件。注意：发气量不如AC猛，低密度厚壁件单独用吃力。
EVA鞋材发AC，XPS板发丁烷，汽车内饰发化学微发泡——各吃各的料。
超临界CO₂、丁烷等物理发泡：气体直接注入熔体，能做出泡孔更细、更均匀的微孔结构，XPS挤塑保温板、汽车内饰微发泡是主力。选它的信号：追求微孔、低密度、连续生产。注意：需要专门的注气设备和工艺窗口，不是加个料那么简单。
空心微珠（玻璃/陶瓷微珠）：不产气，靠预先带进去的空心球物理减重，常用于SMC、人造石、汽车配重。它不改变加工温度，但对分散和混合要求高，容易浮珠或破碎。
泡孔均匀比泡孔大更重要——均匀的微孔轻还结实，大泡孔一捏就塌。
替代对照：进口发泡体系能不能换？先看这张表
采购关心的还是替代。发泡剂的差异常不在发不发得起来，而在产气曲线和残留气味的一致性上。下面列常见替代方向。
| 原用进口方向 | 典型应用 | 可对标方案 | 切换前提 |
|---|
| 进口AC发泡剂 | EVA/PVC鞋材 | 国产AC | 对比发气量、分解温度、黑芯黄变、残留气味 |
| 进口吸热型发泡剂 | 食品包装片材 | 国产碳酸氢钠复配 | 对比产气曲线、食品级合规、黄变 |
| 进口化学发泡母粒 | PP微发泡内饰 | 国产发泡母粒 | 对比密度下降率、表面银纹、浮纤 |
| 进口超临界发泡方案 | 微孔片材/板材 | 国产体系+工艺调试 | 对比泡孔密度、厚度偏差、表面 |
表中所列只是方向参考，实际泡孔形貌和克重偏差仍要上机验证。
发泡剂替代要做发泡倍率和泡孔形貌对比，科隆新材提供公斤级AC/微球试样时附分解温度和发气量数据，客户可以先在发泡线上对比克重偏差和泡孔均匀性。
泡孔一大就塌、一不均就缩？先别怪发泡剂，先看你温度是不是让它分解早了。
行业场景速查：鞋厂和板材厂要的不是一种泡
同样叫发泡，做鞋中底和做保温板，密度、温度、认证要求完全不同。下面按行业拆。
| 行业 | 典型制品 | 客户最先问的参数 | 推荐体系 | 认证要求 |
|---|
| 鞋材 | EVA中底、鞋垫 | 密度、回弹、黄变 | AC+ZnO复配 | RoHS、GB 21027 |
| 包装 | 缓冲内衬、发泡片材 | 缓冲性能、环保可回收 | 物理发泡/吸热型 | GB 4806 |
| 建筑保温 | XPS挤塑板、发泡板 | 导热系数、阻燃等级 | 丁烷物理发泡+阻燃 | GB 8624、B1级 |
| 汽车 | 微发泡内饰、门板 | 减重比例、表面质量 | 化学微发泡母粒 | IATF 16949、低VOC |
| 家居建材 | PVC发泡相框、装饰板 | 表面结皮、密度 | AC+调节剂 | RoHS |
举个场景：做汽车门板微发泡，客户要求减重8%且表面不能有银纹。这时单用AC容易表面粗糙，通常上化学发泡母粒+成核剂，配合快速冷却和背压控制，把泡孔压细、表面压实。
减重5%听着不多，一年跑一万吨料，就是五百吨树脂的钱。
添加量与搭配要点：三条配方线记住就够
发泡配方不用每次从零试，下面三条是行业验证过的通用方案。
要减重就先定目标密度，再选化学发泡还是物理发泡，别拿AC去碰超临界的活。
◆ EVA/PE鞋材：AC 0.3%-1% + 发泡助剂ZnO/硬脂酸锌0.1%-0.3%，把分解温度拉到加工窗口内。
◆ 薄壁食品片材：碳酸氢钠/柠檬酸吸热型0.5%-1.5%，产气温和、不黄变、气味低。
◆ 汽车微发泡内饰：化学发泡母粒0.5%-2%，配合成核剂和快速冷却锁孔，表面才不发花。
搭配要点：发泡剂常和滑石粉成核剂协同——成核剂越多泡孔越细；AC含氮残留气味在密闭内饰件要控量；物理发泡要预留注气和背压设备改造预算；空心微珠单独使用不产气，减重靠体积不靠气体。
发泡：会发也要会稳。
加工与合规红线：温度差二十度，泡孔差一截
发泡配方成败常在温度和剪切上。下面这张表把关键环节列出来。
| 环节 | 参考值 | 做错的后果 |
|---|
| 温度控制 | AC体系170-200℃，助发泡剂按比例 | 温度过高→塌泡，过低→发不起来 |
| 发泡助剂配比 | ZnO/硬脂酸锌0.1%-0.3% | 缺助剂→分解温度偏高、产气曲线陡 |
| 螺杆剪切 | 中低剪切，避免过早成核 | 剪切过强→泡孔合并、表面银纹 |
| 冷却定型 | 快速冷却及时锁孔 | 冷却慢→泡孔长大合并、表面粗糙 |
合规红线：食品接触发泡制品要符合GB 4806；建筑保温板要过GB 8624阻燃B1级；汽车内饰要符合低VOC和IATF 16949；AC类残留分解物气味在密闭件要重点检测。相关检测报告随货归档。
当CO₂能像拧龙头一样精准控制进多少气，塑料能轻到什么程度，今天的答案还不是终点。
FAQ：采购和配方工程师最常问的五个问题
Q1：国产发泡剂能不能替代进口料？
可以，通用鞋材和PVC发泡场景国产AC和发泡母粒与进口差距已经很小，批次稳定的国产品牌够用。但在汽车微发泡、微孔片材等对泡孔均匀性和批次一致性要求高的场景，进口在产气曲线控制和杂质含量上仍有优势。替代要先做公斤级平行测试，对比密度下降率、泡孔均匀性、表面银纹和气味，通过后再放量。要做平行测试的，可以按公斤级寄样，附发气量和分解温度数据一并比对。
Q2：AC发泡为什么会出现黑芯或黄变？
常见原因三个：一是加工温度偏高或停留时间过长，AC过度分解导致局部过热；二是发泡助剂氧化锌加得太多，催化过头；三是与其他含硫、含酸性助剂冲突。排查时先降5-10℃试，再查助剂配比。
Q3：发泡后强度下降多少算正常？
密度每降10%左右，冲击和拉伸通常有一定幅度下降，这是减重的代价。泡孔均匀的微孔结构下降可控且仍保持刚性；如果泡孔粗大不均，强度会断崖式下跌。所以减重设计时要把目标密度和泡孔结构一起定。
Q4：减重5%和减重20%，配方差别在哪？
减重5%用化学发泡母粒小幅产气即可；减重20%以上通常要走物理发泡或更高发气量体系，并配合成核剂和背压工艺，对设备和冷却要求都高一截。别指望靠加一倍AC就能拿到20%减重，那只会塌泡。
Q5：物理发泡一定要改设备吗？
超临界CO₂、丁烷这类物理发泡通常需要注气单元、背压控制和专用螺杆，设备改造投入不小。如果预算有限，可以先用化学微发泡母粒过渡，达到中等减重要求，等订单稳定再考虑上物理发泡线。
选型三步清单：照着选不浪费料
◆ 第1步·定目标密度和壁厚：先算清要减重多少、做多厚、耐不耐温，这决定走化学还是物理路线。
◆ 第2步·选体系：鞋材/PVC结皮用AC+助发泡剂；食品薄壁用吸热型；低密度微孔用物理发泡；填充减重用空心微珠。
◆ 第3步·核工艺与认证：确认温度窗口、发泡助剂配比、冷却锁孔工艺，以及食品级、阻燃、低VOC等认证，先小试做密度和泡孔检测。
泡孔匀了，克重才稳
发泡剂的选型要配合发泡助剂（氧化锌、硬脂酸锌）来调节分解温度，AC放热型和碳酸氢钠吸热型复配可以让泡孔更均匀。科隆新材供应AC发泡剂、微球发泡剂及配套助剂，可提供分解温度、发气量、粒径分布数据；鞋材、汽车内饰、保温材料等不同场景可推荐对应体系，公斤级试样支持先做发泡倍率和泡孔形貌对比。
前年，一家EVA鞋材厂被品牌方扣了一批货——鞋底克重偏差约正负5克，泡孔不均。科隆新材技术人员看了配方，AC发泡剂加了2份但氧化锌只有0.1份，分解温度偏高且不均匀。建议AC约1.5份、氧化锌约0.3份、碳酸氢钠约0.5份复配，寄了样品。客户试产后，泡孔明显均匀，克重偏差降到约正负1.5克，品牌方抽检通过，被扣的五万双鞋终于放行。
AC旁边，氧化锌加了几份？
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。
A batch of EVA soles was foamed, but some felt lighter and some heavier, with pores of varying sizes. The brand's spot inspection failed, and the entire batch of about 50,000 pairs of shoes was held in the warehouse. The formulator checked for a long time and found that the decomposition temperature of the AC foaming agent was too high, and only 0.1 parts of zinc oxide foaming assistant were added, causing uneven decomposition. It's like yeast not being evenly distributed, resulting in bread with some big and some small holes.
Looking down from above the workshop, each piece of foam plastic contains hundreds of millions of tiny bubbles—weight reduction, insulation, and cushioning all rely on them.
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 Foaming Agents: Three Routes – Chemical Foaming, Physical Foaming, and Microballoon Foaming
A foaming agent is not a single thing, but three technical routes: producing gas through chemical decomposition, injecting physical gas, and using pre-set hollow microbeads. Which one to choose depends on how heavy, how thin, and how heat-resistant you need it to be, as well as whether the equipment can be modified. The table below lists the mainstream systems clearly on one page.
| system | Representative varieties | Key parameters | Typical products | Add ratio |
|---|
| Exothermic chemical type | AC azodicarbonamide | Decomposition temperature 180-220℃, requires ZnO/zinc stearate as a foaming aid | EVA shoe materials, PVC/PP foam parts | 0.3%-1% |
| Endothermic chemical | Sodium Bicarbonate/Citric Acid Compound | Moderate air temperature, absorbs heat, low temperature | Food packaging sheet, PE foam | 0.5%-2% |
| Physical foaming | Supercritical CO₂, butane, nitrogen | High-pressure injection of molten material, uniform micropores | XPS insulation board, automotive micro-foamed interior | Gas 0.5%-5% |
| Hollow microbeads | Glass microspheres, ceramic microspheres | Physical filling reduces weight and does not produce gas | SMC, artificial stone, ballast | 5%-20% (by volume) |
Note: The decomposition temperature and gas generation in the table are general parameters; the actual foaming ratio is affected by the process, so refer to the official TDS. First set the target density and wall thickness, then choose the route; don’t start by discussing the grade.
Figure 1 Foaming Agent — Microporous Honeycomb Structure in Plastic Melt
A foaming agent is the yeast of plastic; it must be able to rise and also be stable.
This main character is the yeast of plastics. Ningbo Cologne 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 commonly used additives such as foaming agents, flame retardants, and colorants. The foaming agent category, in essence, is the 'yeast' of plastics—the dough relies on yeast to rise and form a honeycomb, while plastics rely on foaming agents to form pores, expanding volume, reducing density, and lowering both weight and cost.
A foaming agent is to plastic what yeast is to dough—a little makes it rise, the volume multiplies several times, but the density drops.
The mainstream mechanisms are divided into two types. Chemical foaming agents decompose when heated to release gases (nitrogen, carbon dioxide, etc.), nucleate and grow in the melt, and lock the bubbles in place after cooling and solidifying. Azodicarbonamide (AC) is a typical exothermic type, producing a large amount of gas and decomposing at a relatively high temperature, so it must be combined with a foaming assistant to bring the decomposition temperature within the processing window; sodium bicarbonate is an endothermic type, generating gas at a moderate temperature without additional heating, making it suitable for thin-walled and food-grade products. Physical foaming, on the other hand, directly injects supercritical carbon dioxide or high-pressure butane into the melt. The gas dissolves under high pressure, and nucleation occurs instantly upon depressurization, allowing the creation of a more uniform microporous structure.
AC is a stubborn yeast; without being coaxed with zinc oxide, it absolutely refuses to ferment obediently at the temperature required for shoe materials.
The quality of bubbles is actually about three things: nucleation must be uniform, growth must be controlled, and cooling must lock them in promptly. If the temperature is too low, the gas doesn't expand; if the temperature is too high, bubbles merge, collapse, or the surface gets silver streaks. That's why in the industry people often say: just causing foam is only the beginning, achieving stable foaming is the real skill.
The KPI for a foaming agent is just one thing: release it when it should be released, and don't release it randomly when it shouldn't be.
Quick check by type: AC is the main material for shoes, sodium bicarbonate takes a mild approach, supercritical CO₂ is used for micropores.
The varieties look mixed, but grasping a few main lines can cover most applications.
High heat paired with low heat prevents the bubbles from being off-center — a single foaming agent is like using one knife to cut all materials; sooner or later it will collapse.
AC Azodicarbonamide: The mainstay of chemically exothermic foaming agents, it produces a large amount of gas and has a high cost-performance ratio. It is most commonly used in EVA shoe materials and PVC foamed parts. Signals for choosing it: making shoe midsoles, foamed slippers, PP/PVC skin-foam boards. Note: Its decomposition temperature is relatively high at 180-220°C, so a foaming aid must be used; decomposition residues have a slight odor and a tendency to yellow, so caution is needed for light-colored and food-grade applications.
Supply Reminder: AC foaming agents and foaming auxiliaries can be supplied in coordination by Cologne New Materials, with decomposition temperature and gas generation data attached for each batch. Kilogram-level samples support preliminary comparison of foaming ratios.
Foaming auxiliaries (zinc oxide, zinc stearate, etc.): They do not produce gas themselves; their role is to lower the decomposition temperature of AC and make the gas production curve more gradual. Adding 0.1%-0.3% can reduce the decomposition temperature of AC from around 200°C to about 160°C. They are partners with AC in shoe material formulations. Note: Adding too much can cause yellowing and affect whiteness.
Sodium bicarbonate/citric acid compound: endothermic foaming agent, low decomposition temperature, moderate gas production, does not increase temperature, more friendly for food-grade applications. Signals for choosing it: making PE food packaging sheets, thin-wall foaming, light-colored parts sensitive to odor and yellowing. Note: The gas production is not as strong as AC, and using it alone on low-density thick-walled parts is demanding.
EVA shoe materials release AC, XPS boards release butane, and car interiors release chemical micro-foam—each releases its own material.
Supercritical CO₂, butane, and other physical foaming: gas is directly injected into the melt, which can create finer and more uniform microporous structures. It is primarily used for XPS extrusion insulation boards and micro-foaming in automotive interiors. Signals for choosing it: seeking micropores, low density, and continuous production. Note: special gas injection equipment and process windows are required; it’s not as simple as just adding a material.
Hollow microspheres (glass/ceramic microspheres): They do not generate gas and rely on the pre-introduced hollow spheres to reduce weight physically. They are commonly used in SMC, artificial stone, and automotive counterweights. They do not change the processing temperature but require high standards for dispersion and mixing, and they are prone to floating or breaking.
Uniform pores are more important than large pores—uniform micropores are light yet sturdy, while large pores collapse with a squeeze.
Alternative comparison: Can the imported foaming system be replaced? First, look at this table
What procurement cares about is still alternatives. The differences in foaming agents are usually not about whether they foam or not, but about the consistency of the gas production curve and residual odor. Below are common alternative directions.
| Original imported direction | Typical Applications | Benchmark solution | Switch premise |
|---|
| Imported AC foaming agent | EVA/PVC Shoe Material | Domestic AC | Compare gas emission, decomposition temperature, black core yellowing, and residual odor |
| Imported endothermic blowing agent | Food Packaging Sheet | Domestic sodium bicarbonate compound | Comparison of gas production curves, food-grade compliance, yellowing |
| Imported chemical foaming masterbatch | PP micro-foamed interior | Domestic foaming masterbatch | Compare density drop rate, surface silver streaks, and floating fibers |
| Imported supercritical foaming solution | Microporous sheet/plate | Domestic System Process Debugging | Compare pore density, thickness deviation, and surface |
The table only provides directional reference; the actual bubble morphology and basis weight deviations still need to be verified on the machine.
When replacing the foaming agent, it is necessary to compare the foaming ratio and pore morphology. When Kolon New Material provides kilogram-scale AC/microball samples, decomposition temperature and gas generation data are included. Customers can first compare the weight deviation and pore uniformity on the foaming line.
Do the bubbles collapse when they get big, or shrink if uneven? Don't blame the foaming agent first; check if your temperature is causing it to decompose too early.
Quick Industry Reference: Shoe factories and board factories do not need the same kind of foam
Although both are called foaming, the density, temperature, and certification requirements are completely different for making shoe midsoles and making insulation boards. Below is a breakdown by industry.
| Industry | Typical products | The parameters the customer asked about first | Recommendation system | Certification requirements |
|---|
| Shoe materials | EVA midsole and insole | Density, resilience, yellowing | AC ZnO Compounding | RoHS, GB 21027 |
| Packaging | Cushion lining, foam sheet | Cushioning performance, environmentally friendly and recyclable | Physical Foaming / Heat-Absorbing Type | GB 4806 |
| Building insulation | XPS extruded board, foam board | Thermal conductivity, flame retardant rating | Butane physical foaming flame retardant | GB 8624, B1 level |
| Car | Micro-foamed interior trim and door panels | Weight reduction ratio, surface quality | Chemical micro-foaming masterbatch | IATF 16949, low VOC |
| Home building materials | PVC foam photo frames and decorative panels | Surface crusting, density | AC modulator | RoHS |
For example: in micro-foaming car door panels, the customer requires an 8% weight reduction and no silver streaks on the surface. At this time, using AC alone can easily result in a rough surface. Typically, a chemical foaming masterbatch is added as a nucleating agent, combined with rapid cooling and back pressure control, to refine the foam cells and compact the surface.
A 5% weight reduction doesn't sound like much, but running 10,000 tons of material in a year amounts to the cost of 500 tons of resin.
Dosage and key points of combination: Remembering just three formula lines is enough
Foaming formulas don't need to be tested from scratch every time; the following three are industry-verified universal solutions.
To lose weight, first set the target density, then choose between chemical foaming or physical foaming; don't use AC to touch supercritical activity.
◆ EVA/PE shoe materials: AC 0.3%-1%, foaming aid ZnO/zinc stearate 0.1%-0.3%, to adjust the decomposition temperature within the processing window.
◆ Thin-walled food sheets: endothermic type with sodium bicarbonate/citric acid 0.5%-1.5%, moderate gas production, no yellowing, low odor.
◆ Micro-foamed automotive interiors: Chemical foaming masterbatch 0.5%-2%, combined with nucleating agents and rapid cooling to lock the cells, so the surface does not become mottled.
Key points for formulation: Blowing agents are often used together with talc as nucleating agents — the more nucleating agents, the finer the pores; AC contains nitrogen and the residual odor needs to be controlled in enclosed interior parts; physical foaming requires budgeting for gas injection and backpressure equipment modifications; hollow microspheres alone do not generate gas, weight reduction depends on volume rather than gas.
Foaming: You need to be able to foam and also be stable.
Processing and Compliance Red Lines: Temperature Difference of Twenty Degrees, Foaming Hole Difference by One Segment
The success or failure of a foaming formula often depends on temperature and shear. The table below lists the key steps.
| link; segment; part | Reference value | The consequences of doing wrong |
|---|
| Temperature control | AC system 170-200℃, blowing agent in proportion | If the temperature is too high → bubbles collapse; if too low → won't rise |
| Foaming agent ratio | ZnO/Zinc Stearate 0.1%-0.3% | Lack of additives → decomposition temperature is relatively high, gas production curve is steep |
| Screw shear | Medium to low shear, avoid premature nucleation | Excessive cutting → pore merging, surface silver streaks |
| Cooling and shaping | Rapid cooling and timely lock hole | Slow cooling → pore growth and merging, rough surface |
Compliance Red Lines: Food-contact foamed products must comply with GB 4806; building insulation boards must pass GB 8624 flame retardant B1 level; automotive interiors must meet low VOC and IATF 16949 standards; residual decomposition odor of AC type should be重点检测 in enclosed parts. Relevant test reports should be filed with the goods.
If CO₂ could be precisely controlled like turning a faucet to adjust the amount, and plastics could be made extremely light, today's answers would still not be the final endpoint.
FAQ: The Five Most Common Questions Asked by Purchasing and Formulation Engineers
Q1: Can domestic foaming agents replace imported ones?
Yes, for general shoe materials and PVC foaming applications, the gap between domestic AC and foaming masterbatch and imported ones has become very small, and stable domestic brands are sufficient. However, in automotive micro-foaming, microporous sheets, and other scenarios requiring high uniformity of foam cells and batch consistency, imports still have advantages in gas evolution control and impurity content. Replacement requires kilogram-scale parallel testing first, comparing density reduction rate, foam cell uniformity, surface silver streaks, and odor; only after passing these tests can large-scale use be considered. For those needing parallel testing, samples can be sent at kilogram scale along with gas evolution and decomposition temperature data for comparison.
Q2: Why does AC foam develop black cores or yellowing?
There are three common causes: first, the processing temperature is too high or the residence time is too long, causing AC to over-decompose and lead to local overheating; second, too much zinc oxide is added as a foaming agent, leading to over-catalysis; third, conflicts with other sulfur-containing or acidic auxiliaries. During troubleshooting, first try reducing the temperature by 5-10°C, then check the auxiliary ratio.
Q3: How much strength loss after foaming is considered normal?
For every approximate 10% decrease in density, impact and tensile properties usually decrease to some extent; this is the cost of weight reduction. A microporous structure with uniform pores decreases in a controllable way and still maintains rigidity; if the pores are large and uneven, the strength will drop drastically. Therefore, in weight reduction design, the target density and pore structure should be determined together.
Q4: What is the difference in the formula between a 5% weight loss and a 20% weight loss?
For a 5% weight reduction, a chemical foaming masterbatch producing a small amount of gas is sufficient; for a weight reduction of more than 20%, you usually need to use physical foaming or a system with a higher gas output, combined with a nucleating agent and backpressure process, which significantly increases the requirements for equipment and cooling. Don't expect to achieve a 20% weight reduction just by doubling the AC, that will only collapse the foam.
Q5: Do you have to change the equipment for physical foaming?
Physical foaming with supercritical CO₂ or butane usually requires a gas injection unit, backpressure control, and specialized screws, so equipment modification involves a significant investment. If the budget is limited, you can first transition using chemical micro-foam masterbatch to achieve moderate weight reduction, and consider moving to a physical foaming line once orders are stable.
Three-step selection checklist: Choose according to avoid wasting materials
◆ Step 1: Set target density and wall thickness: first calculate how much weight is needed, how thick to make, and whether it can withstand temperatures. This determines whether to go for chemical or physical approaches.
◆ Step 2: Select system: use AC auxiliary foaming agents for shoe materials/PVC leather; Endothermic types for food thin-walls; Use physical foam for low-density micropores; Use hollow microbeads for weight reduction in filling.
◆ Step 3·Nuclear Process and Certification: Confirm temperature windows, foaming additive ratios, cooling keyhole processes, as well as food-grade, flame-retardant, low VOC certifications, and conduct small-scale testing of density and cell cells.
Even Foam Ensures Weight Stability
The selection of foaming agents should be combined with foaming additives (zinc oxide, zinc stearate) to adjust decomposition temperature. The combination of AC exothermic type and sodium bicarbonate endothermic type can make the cells more uniform. Kolon New Materials supplies AC foaming agents, microsphere foaming agents, and supporting additives, providing data on decomposition temperature, gas output, and particle size distribution; Different scenarios such as shoe materials, automotive interiors, and insulation materials can recommend corresponding systems. Kilogram-level samples support foaming rate and bubble morphology comparison first.
Two years ago, an EVA shoe material factory had a batch of goods withheld by the brand—the shoe sole weight deviation was about ±5 grams, and the bubbles were uneven. Technical staff from Kolon New Materials reviewed the formula and found that 2 parts AC foaming agent were added, but only 0.1 parts zinc oxide, resulting in a relatively high and uneven decomposition temperature. They recommended a mixture of about 1.5 parts AC, 0.3 parts zinc oxide, and 0.5 parts sodium bicarbonate, and sent samples. After trial production, the customer's bubble holes were clearly uniform, the weight deviation dropped to about plus or minus 1.5 grams, the brand passed the spot check, and the 50,000 pairs of shoes that were deducted were finally released. Next to the
AC, how many parts of zinc oxide were added?
Statement: The brands, trademarks, and product names mentioned in this article belong to their respective original manufacturers. This article is a third-party material selection knowledge sharing. The grades, parameters, prices, certifications, and application cases mentioned in the article are for reference only. Please refer to the latest official information and batch test reports from each manufacturer. This article does not constitute any procurement or investment advice; readers are responsible for any actions based on it
