采购小李把报价单拍在桌上："同样叫ULDPE，你这袋比他那袋贵四千，差在哪？"
工艺师傅捏起一粒料往天花板一抛，料软塌塌落回手心："你这袋能上七层共挤机不打滑，他那袋开机就飘膜、热封粘不牢，你说差在哪。"
一桌人不吭声了。ULDPE这东西，名字听着像LDPE的弟弟，实际密度能压到0.912以下，软得像块橡皮泥，却是高端包装膜里没人敢明说的秘密武器。正牌贵，回料不敢用，副牌到底怎么捡？今天聊透。
密度跌破0.912，软和韧一起拉满
ULDPE，超低密度聚乙烯，密度一般在0.885到0.912 g/cm³之间，靠茂金属催化剂做出来。它比普通LLDPE软得多，拉伸和抗穿刺却强一大截，低温热封起始温度低，密封窗宽。
说白了，别人要加三层料才封得住的口，它一层就封住了，还封得牢。拉伸缠绕膜、重载包装膜、农膜、复合膜的热封层，都是它的地盘。膜做薄、做软、做省料，靠的就是它。
全球前三国外大厂，膜圈心里有数
全球ULDPE产能高度集中在几家茂金属技术老牌手里。按产能口径，埃克森美孚、陶氏、利安德巴塞尔三家加上SABIC、英力士，合计占了全球ULDPE铭牌产能的大半。
陶氏靠AFFINITY和ATTANE两条线，埃克森美孚靠EXACT聚烯烃弹性体和Enable系列，利安德巴塞尔在茂金属PE上也有完整牌号。这里口径说一句：ULDPE和POP、mLLDPE在产品线上常叠在一起，数据源排名略有出入，按梯队看更稳妥。
副牌不是边角料，是同一条茂金属线上的擦边档
先把副牌是什么说死。副牌是同一厂家同一牌号里，出厂检验没完全踩中正牌指标的那一部分。同一批茂金属聚合产物，全达标贴正牌，个别指标小幅飘就是副牌。它还是原厂原生粒子，分子链和正牌同源，只是密度、熔指、热封强度在化验单上擦了边。
四大来源不变：开停车头尾料、牌号切换过渡料、工艺波动致个别指标超标的批次、副线尾料。
再划清边界：副牌≠回料≠再生料。回料是加工边角再造粒，受过一次热历史；再生料是回收料，性能波动大。副牌是原厂同批料，差的只是那一纸合格章。吹膜的都懂，膜薄到几十微米，料稍微不纯，鱼眼、晶点、破膜全来了。
陶氏：ATTANE，ULDPE这个名字的老祖宗
陶氏是茂金属聚乙烯的先行者，INSITE技术起家。ULDPE这块的代表就是ATTANE系列，密度做到0.900上下，软韧和热封是招牌，做重载包装膜和拉伸膜的人都认得这个牌子。
陶氏副牌常见浮动点是熔指或密度擦边，颗粒外观可能带点色差。它家副牌适合做拉伸缠绕膜、内衬膜、一般复合膜热封层，性能冗余够；但要做食品级高阻隔层、医疗级膜，还是得走正牌牌号和认证。
埃克森美孚：EXACT和Enable，膜又薄又快
埃克森美孚的EXACT聚烯烃弹性体和Enable mPE，在高速吹膜和流延膜上口碑很硬。它家料的特点是加工性好，能上更高线速，膜的光学和热封平衡得漂亮，重载袋和食品包装膜用得多。
它家副牌通常是熔指小幅偏离或色相偏一点，分子结构没换。拿来做工业包装膜、农膜、拉伸膜下卷，性价比突出；做要求严格的食品接触级薄制品，建议先拿样过迁移测试。
利安德巴塞尔：茂金属PE的另一把好手
利安德巴塞尔在茂金属聚乙烯上产品线完整，ULDPE和mLLDPE牌号跨度大，欧洲和北美农膜、包装膜市场铺得很开。它的料批次一致性和加工窗口口碑稳。
它家副牌因为欧洲货源批次跨度大，采购前一定对批号和COA。适合做非食品级包装膜、衬垫膜、发泡基材这些不挑认证的活儿，价格弹性比正牌舒服不少。
捡ULDPE副牌，别踩这四个坑
头一条，密度是底线不是噱头。低于0.885的"超软"料要警惕，可能掺了弹性体或别的东西，膜的力学会塌。
第二，热封强度要实测。副牌最常见的浮动就是热封起始温度和热封强度，上机先封个小样，低温封口不漏才算数。
第三，用途对号。食品级、医疗级膜别碰副牌；工业包装、农膜、内衬，副牌才划算。
第四，认原厂标识。大包装小包装都行，但要能追批号、带COA，没标识的低价货先怀疑回料。
科隆仓库现货｜ULDPE质量
主推品牌：陶氏、埃克森美孚、利安德巴塞尔
主要牌号：ATTANE/AFFINITY系列、EXACT/Enable系列、茂金属PE牌号
包装规格：大包装/小包装均有备货
仓库现货通常在4000吨上下
小包副牌备货600-900吨、箱装副牌备货250-450吨、大包料/吨包料备货2650-3150吨
供应保障：检测单随货
选型口诀 + 扬州一个包装膜的真实账
选型口诀记五条：
1. 先定膜种再选料，食品医疗级别省料；
2. 密度卡在0.885-0.912，太硬太软都不对；
3. 热封强度上机实测，别信化验单一张纸；
4. 副牌追原厂批号，COA和标识缺一不可；
5. 先试小卷再放大，破膜鱼眼一起算。
扬州有家做工业包装膜的客户，之前图便宜进了一批"低价ULDPE"，开机三天破膜率从0.5%飙到6%，一卷卷膜下不了机，赔了上游客户一批订单。后来换成进口大厂副牌ULDPE，按批号逐卷测热封强度和拉伸，破膜率压回0.4%，每吨成本还降了近八百块。
这就是膜圈的账——料软一度，成本省一截，可一旦热封拉胯，赔的是整卷膜加客户信任。宁波市科隆新材料有限公司做进口聚烯烃副牌多年，包装膜料这块每年调的案子不少，说白了就是帮你开机前把热封那道先验明白。
Procurement Xiao Li slapped the quotation sheet on the table: "It's also called ULDPE, but yours bag is 4,000 more expensive than theirs. What's the difference?" "
The craftsman picked up a piece of material and tossed it to the ceiling. The material fell softly back into his palm: "Your bag can run through seven layers of co-extruder without slipping, but his bag has a floating film and can't be sealed tightly when it starts. What do you think is the difference?" "
The whole table fell silent." ULDPE sounds like the younger brother of LDPE, but its actual density can be reduced below 0.912, as soft as a piece of modeling clay. But it's a secret weapon in high-end packaging films that no one dares to admit. Genuine brands are expensive, recycled materials are hesitant to use, so how exactly do you pick up secondary brands? Let's talk about this thoroughly today.
Density drops below 0.912, stretching both soft and tough to the
ULDPE. Ultra-low density polyethylene generally ranges from 0.885 to 0.912 g/cm³, produced using metallocene catalysts. It is much softer than ordinary LLDPE, but its tensile and puncture resistance is much stronger. The starting temperature for low-temperature heat sealing is low, and the sealing window is wide.
To put it simply, while others need three layers of material to seal the opening, this one layer seals it and seals it firmly. Heat sealing layers for stretch stretch film, heavy-duty packaging film, agricultural film, and composite film are all its domains. Thin, soft, and material-saving films rely on this membrane.
The world's top three foreign manufacturers have a clear understanding of the membrane industry
Global ULDPE capacity is highly concentrated in the hands of several established metallocene technology companies. By capacity basis, ExxonMobil, Dow, and Leanderbasel, plus SABIC and INEOS, together account for most of the global ULDPE nameplate production capacity.
Dow relies on AFFINITY and ATTANE lines, ExxonMobil relies on ACT polyolefin elastomers and the Enable series, and LeanderBasel also has a complete range of metallocene PE brands. To put it simply: ULDPE and POP and mLLDPE are often stacked together in product lines, with slight differences in data source rankings, so it's safer to look at tiers.
Sub-brand isn't scrap material; it's just a marginal barrier on the same metallocene line .
First, define what sub-brand is. Sub-brand is the part of the same manufacturer and grade that didn't fully meet the genuine brand standards during factory inspection. If the same batch of metallocene polymer products meets standards and is labeled as genuine, and a few indicators fluctuate slightly, that's sub-brand. It's still original factory original particles, with molecular chains sharing the same origin as the genuine brand, but density, melting index, and heat seal strength are just marginal on the test report.
The four main sources remain unchanged: start-stop and tail materials, grade switching transition materials, batches with process fluctuations causing some indicators to exceed standards, and auxiliary line tail materials.
Further demarcating boundaries: secondary brand ≠ recycled materials≠ recycled materials. Remixed material is processed corners and then pelletized, having undergone a thermal cycle; Reclaimed material is recycled material with significant performance fluctuations. Sub-brands are the same batch as the original factory; the only difference is the quality stamp. Film blowers know that films can be as thin as tens of microns, and if the material is slightly impure, fish-eye spots, crystal spots, and film breakage all appear.
Dow: ATTANE, the ancestor of the ULDPE name
Dow is a pioneer of metallocene polyethylene, starting with INSITE technology. The representative of ULDPE is the ATTANE series, with density around 0.900, soft toughness and heat sealing as its signature products. Anyone making heavy-duty packaging films and stretch films knows this brand.
Dow secondary brands commonly have floating points such as melt fingers or density edges, and the pellets may show some color differences. Their secondary brands are suitable for stretch stretch films, liner films, and general composite film heat sealing layers, with sufficient performance redundancy; but to make food-grade high-barrier films or medical-grade films, you still need the official brand and certification.
ExxonMobil: EXCELLENT and Enable, thin and fast membranes
ExxonMobil's ACT polyolefin elastomer and Enable mPE have a strong reputation for high-speed blown and cast films. Their material is characterized by good processability, can be applied at higher line speeds, and the optical and heat sealing membranes are beautifully balanced, widely used in heavy-duty bags and food packaging films.
Their sub-brand usually has a slight melt index deviation or slightly offset hue, with no change in molecular structure. Used for industrial packaging films, agricultural films, and stretch film underrolling, offering excellent cost-effectiveness; For strict food contact-grade thin products, it's recommended to get samples for migration testing first.
Lianderbasell: Another expert in metallocene PE
LianderBasel has a complete product line in metallocene polyethylene, with wide range of ULDPE and mLLDPE grades, and the European and North American agricultural and packaging film markets are very open. Its material batch consistency and stable reputation at processing windows.
Their sub-brand has a wide range of European supply batches, so batch numbers and COA must be checked before purchasing. It's suitable for non-food-grade packaging films, liner films, foam substrates—jobs that don't require certification, and the price flexibility is much more comfortable than genuine brands.
Pick up ULDPE secondary brands, don't fall into these four pitfalls
First one: density is the bottom line, not a gimmick. Be wary of 'super-soft' materials below 0.885, as they may contain elastomers or other substances, and the membrane's strength will collapse.
Second, measure the heat seal strength. The most common variation in secondary brands is the initial heat seal temperature and seal strength. Seal a sample before machine use, and the low-temperature seal must be sealed without leaks.
Third, use is matched. Food-grade and medical-grade films should avoid secondary brands; Industrial packaging, agricultural films, and liners are more cost-effective for secondary brands.
Fourth, recognize the original manufacturer's label. Both large and small packages are fine, but if you can trace the batch number and carry COA, be suspicious of low-priced items without the marking.
Cologne warehouse in-stock | ULDPE quality
Main brands: Dow, ExxonMobil, Liander Basel
Main grades: ATTANE/AFFINITY series, EXACT/Enable series, metallocene PE grades
Packaging specifications: both large and small packages are stocked
warehouse stock usually around 4000 tons
Small parcel sub-brand stock 600-900 tons, containerized sub-brand stock 250-450 tons, large package/ton package material stock 2650-3150 tons
Supply guarantee: test form with goods
Selection tips + real account of a packaging film in Yangzhou
Five selection tips:
1. Decide on film type before material selection, food-medical grade material savings;
2. Density stuck between 0.885-0.912—too hard or too soft is wrong;
3. Heat seal strength tested on machine, don't trust a single lab sheet;
4. For secondary brands, follow the original factory batch number; COA and marking are both indispensable;
5. Test the small roll first, then zoom in, calculate film breakage and fish eye damage together.
Yangzhou has a customer specializing in industrial packaging film. Previously, they bought a batch of "low-priced ULDPE" products cheaply. Within three days of operation, the film breakage rate jumped from 0.5% to 6%, and one roll couldn't be unloaded, resulting in a loss for a batch of upstream customers' orders. Later, they switched to imported major manufacturers' sub-brand ULDPE, measuring heat seal strength and tensile strength by batch number, reducing film breakage rate back to 0.4%, and reducing cost per ton by nearly 800 yuan.
This is the price of the film ring—the material is softer once, saving a bit, but if the heat seal fails, the loss is the whole roll of film and customer trust. Ningbo Kelong New Materials Co., Ltd. has been doing imported polyolefin sub-brands for many years, handling many cases annually for packaging film materials. Simply put, they help you understand the heat sealing step before starting the machine
