很多人以为聚丁二烯橡胶（BR）就是做轮胎的高顺顺丁胶。真相是：BR家族里藏着一支专门给塑料“补钙”的小众分支——LCBR，低顺式聚丁二烯。
它顺式含量只有三成多，专门当HIPS、ABS的抗冲改性剂。轮胎厂看不上它，塑料改性厂却离不开它。就是这么个不起眼的料，副牌里的学问比轮胎胶还深。
小众梯队，不硬排前三
LCBR，低顺式聚丁二烯橡胶，用锂系催化剂做，顺式1,4含量约34%到40%，带一定乙烯基结构。它溶在苯乙烯里参与HIPS接枝，橡胶颗粒分散在聚苯乙烯基体里，把脆硬的GPPS撑成耐摔的HIPS。
这品类小众，国外大厂不算多，按实际梯队排：韩国锦湖石化（KUMHO LBR，KBR-710系列，顺式34.5%）、阿朗新科（Buna CB锂系低顺系列，CB 45 VP顺式38%、CB 565 T）、意大利埃尼Versalis（Intene低顺BR，专供HIPS/ABS）。Synthos的SYNTECA、JSR、LG化学跟在后面。（口径：市占/产能，行业报告）
为什么做HIPS非得用低顺，不用高顺？道理在接枝反应。低顺BR带一定乙烯基，溶进苯乙烯里接枝活性高，橡胶颗粒能按设计粒径分散开；高顺BR顺式含量九成以上，接枝活性差，做出来的HIPS要么冲击上不去、要么发乌不透明。所以HIPS改性这一行，认的就是锂系低顺这一支。
副牌是话不多的远房表弟
LCBR副牌怎么来的？它是锂系聚合线上下来的料，工艺波动小，但顺式含量和凝胶含量卡得严。装置开停车头尾料、牌号切换过渡料、凝胶含量或门尼小幅越线的批次，就成了副牌。
打个比方：LCBR副牌像正牌那个话不多的远房表弟，同一批锂系聚合下来，只是顺式含量和凝胶含量的化验单上少盖了个合格章，接枝活性跟正牌没差。
边界还是那句话：副牌是原厂原生胶粒；回料是你做HIPS的边角料再造粒，已经受过一次热历史；再生料是废塑料回来的，凝胶和杂质根本控不住。LCBR这种料，凝胶含量直接决定HIPS的冲击强度，副牌凝胶一旦超标，做出来的壳一摔就裂。
锦湖LBR：HIPS基材的招牌
锦湖石化的KUMHO LBR是LCBR的招牌，KBR-710S/710H顺式34.5%、乙烯基14.5%，就是奔着HIPS基材去的。它家副牌多出自门尼或凝胶的小幅越线，特点是接枝反应活性稳，做通用HIPS壳体、玩具外壳的厂拿来顶正牌，冲击强度微调配方就能接上。
阿朗新科Buna CB：浅色件的色相
阿朗新科的Buna CB锂系低顺线，CB 45 VP顺式38%、CB 565 T专门标了塑料改性。它家副牌分子结构规整、杂质低，做高透明或浅色HIPS时色相干净。要注意阿朗新科副牌门尼区间偏窄，换牌号时配方要跟着调。
Versalis Intene：普通壳体的性价比
意大利埃尼旗下的Versalis，Intene低顺BR是HIPS/ABS抗冲改性的老牌产品，欧洲市场根基深。它家副牌量大、性价比高，适合做普通电器外壳、日用壳体的改性厂。副线尾料集中在顺式含量的小幅飘移，做一般增韧件够用。
三个坑，凝胶是红线
LCBR副牌三个坑。头一个是凝胶含量。这是LCBR首先该盯的指标——凝胶高了，HIPS的橡胶粒径分布就乱，冲击强度上不去。
再一个，是把高顺BR（Nd-BR）当LCBR买。高顺胶是做轮胎的，溶进苯乙烯里接枝活性差，做HIPS根本不顶用。还有一个是门尼。门尼飘了，接枝粘度跟着变，HIPS的熔融指数就跑。
另外提醒一句：LCBR副牌跟正牌掺着用，接枝配方要重新跑一遍。橡胶粒径分布对比例很敏感，正副牌按几比几掺，得先在小试反应罐里把粒径和冲击强度验证清楚，再放大到产线。
科隆仓库现货｜LCBR内贸
主推品牌：韩国锦湖石化、阿朗新科、意大利Versalis埃尼
主要牌号：KUMHO LBR（KBR-710）、Buna CB、Intene
包装规格：原厂原包，分大包装与小包装两种；小包副牌、箱装副牌、大包料/吨包料分档码放，按批量备货
仓库现货：LCBR副牌仓库现货通常在2000-5000吨
现货明细：小包副牌备货300-600吨、箱装副牌备货150-300吨、大包料/吨包料备货1500-4100吨
供应保障：批次留样可溯，每批进厂留底留样，批次台账可查
记四条，再做接枝
1. 先确认是锂系低顺，别拿高顺BR来凑。
2. 凝胶含量是红线，进厂必测。
3. 门尼对HIPS熔融指数，换料先打接枝小样。
4. 透明、浅色件，色相和凝胶一起卡。
宜昌有家做家电外壳和日用壳体HIPS改性的客户，之前全用锦湖正牌LBR，增韧剂成本压不下。后来在普通壳体配方里掺了两成Versalis副牌Intene，凝胶含量测下来控制在0.02%以内，落球冲击跟全正牌配方只差一焦耳上下，一吨改性料成本省下来七百多块，一年省出小几十万。这就是LCBR副牌的用法——高透明、高要求件守住正牌，普通壳体用副牌把增韧成本拉平。宁波市科隆新材料有限公司做进口低顺BR副牌多年，凝胶、门尼、接枝活性进厂前先帮你核一遍。
Many people think that polybutadiene rubber (BR) is just high-cis polybutadiene used for making tires. The truth is: within the BR family, there is a niche branch that is specifically used to "fortify" plastics—LCBR, low-cis polybutadiene.
It has a cis content of only a little over 30%, specifically used as an impact modifier for HIPS and ABS. Tire manufacturers don't value it, but plastic modification factories can't do without it. It's just such an inconspicuous material, yet the knowledge within its secondary brands is even deeper than tire rubber.
Niche tier, not firmly ranked in the top three
LCBR, low-cis polybutadiene rubber, made with lithium-based catalysts, has a cis-1,4 content of about 34% to 40% and contains a certain amount of vinyl structure. It dissolves in styrene for HIPS grafting, with rubber particles dispersed in the polystyrene matrix, turning brittle GPPS into impact-resistant HIPS.
This category is niche, and there are not many major foreign manufacturers. According to the actual tiers: Kumho Petrochemical of South Korea (KUMHO LBR, KBR-710 series, cis 34.5%), Arlanxeo (Buna CB lithium-based low-cis series, CB 45 VP cis 38%, CB 565 T), Italy's Eni Versalis (Intene low-cis BR, exclusively for HIPS/ABS). Synthos's SYNTECA, JSR, and LG Chem follow behind. (Diameter: market share/capacity, industry report)
Why must low-cis BR be used for making HIPS, and not high-cis? The reason lies in the grafting reaction. Low-cis BR contains a certain amount of vinyl groups, which dissolve in styrene and have high grafting activity, allowing the rubber particles to disperse according to the designed particle size; high-cis BR has a cis content of over 90%, with poor grafting activity, resulting in HIPS that either doesn't have sufficient impact strength or turns cloudy and opaque. Therefore, in the HIPS modification field, the focus is on the lithium-based low-cis type.
Auxiliary brand is a quiet distant cousin
How does the LCBR by-product grade come about? It comes from the lithium-based polymer line; the process fluctuation is small, but the cis content and gel content are strictly controlled. Material from the start and end of the plant operation, transitional material during grade switching, or batches where the gel content or Mooney viscosity slightly exceed the limits become the by-product grade.
For example: The sub-brand of LCBR is like the quiet distant cousin of the main brand. They are from the same batch of lithium-based polymers, but the lab reports for cis content and gel content just lack a certified stamp, while the grafting activity is no different from the main brand.
The bottom line is still the same: sub-brands use original factory virgin granules; regrind is the leftover material from your HIPS production, re-pelleted, and has already been through a thermal history once; recycled material comes from waste plastics, and gel and impurities are uncontrollable. For LCBR grade material, the gel content directly determines the impact strength of HIPS. Once the gel content in sub-brand materials exceeds the standard, the produced shells will crack as soon as they are dropped.
Kumho LBR: The signature of HIPS substrate
Kumho Petrochemical's KUMHO LBR is the flagship of LCBR. The KBR-710S/710H has a cis content of 34.5% and vinyl content of 14.5%, specifically aimed at HIPS substrates. Their secondary brands often slightly exceed the Mooney or gel limits. The feature is stable graft reaction activity, so manufacturers making general HIPS housings or toy housings use them as a substitute for the main brand; just fine-tuning the formulation for impact strength is enough to match.
Aron New Buna CB: Hue of light-colored parts
Alang Xin'ke's Buna CB Li-based low-MFI series includes CB 45 VP with a cis content of 38% and CB 565 T, specifically labeled for plastic modification. Their sub-brand has a regular molecular structure and low impurities, resulting in clean color tones when making high transparency or light-colored HIPS. It should be noted that the MFI range of Alang Xin'ke's sub-brand is relatively narrow, so the formulation needs to be adjusted when switching grades.
Versalis Intene: Cost-effective ordinary housing
Versalis, a subsidiary of Italy's Eni, Intene Low-flow BR is a long-established product for HIPS/ABS impact modification, with a solid foundation in the European market. Its sub-brand has a large volume and high cost-performance, suitable for modification factories making ordinary appliance housings and daily-use cases. The by-product material of the sub-line is mainly affected by slight fluctuations in the cis content, which is sufficient for general toughening parts.
Three pits, the gel is the red line
There are three pitfalls in LCBR by-product. The first one is gel content. This is the indicator that LCBR should focus on first — if the gel content is high, the rubber particle size distribution of HIPS becomes irregular, and the impact strength cannot improve.
Another thing is treating Gaoshun BR (Nd-BR) as if it were LCBR. Gaoshun rubber is used for making tires, and it has poor grafting activity when dissolved in styrene, so it’s basically useless for making HIPS. Another factor is Mooney. If the Mooney value fluctuates, the grafted viscosity changes accordingly, and the melt index of HIPS will vary.
One more reminder: When mixing LCBR secondary brand with the primary brand, the grafting formula needs to be rerun. The particle size distribution of the rubber is very sensitive to the proportion. When mixing the primary and secondary brands in certain ratios, you need to first verify the particle size and impact strength in a small test reactor before scaling up to the production line.
Cologne warehouse in stock | LCBR domestic trade
Main recommended brands: Korea Kumho Petrochemical, Arlanxeo, Italy Versalis Eni
Main grades: KUMHO LBR (KBR-710), Buna CB, Intene
Packaging specifications: Original factory packaging, available in large and small packs; small packs are sub-branded, boxed sub-branded, large pack materials/ton bags are graded and stacked, stocked according to batch quantity.
Warehouse spot: LCBR secondary brand warehouse spot is usually 2,000-5,000 tons
Spot details: Small package secondary brand stock 300-600 tons, boxed secondary brand stock 150-300 tons, large package/material per ton stock 1500-4100 tons
Supply Assurance: Batch samples can be traced; each batch entering the factory is retained for records and sampling, and batch ledgers can be checked.
Mark four lines, then do the grafting
1. First confirm that it is a low-flow lithium series; don't substitute with high-flow BR.
2. Gel content is the red line; it must be tested upon entering the factory.
3. Meny tests the melt index of HIPS, and when changing materials, first run a grafting sample.
4. Transparent or light-colored parts, match the hue together with the gel.
There is a customer in Yichang who manufactures housings for home appliances and daily-use cases using HIPS modification. Previously, they used only the genuine LBR from Kumho, but the cost of toughening agents could not be reduced. Later, in ordinary casing formulations, they mixed in 20% of Versalis' off-brand Intene. The measured gel content was controlled within 0.02%, and the drop impact was only about one joule lower than that of the full genuine formulation. This saved over 700 yuan per ton of modified material, amounting to tens of thousands per year. This is how the LCBR off-brand is used—reserve genuine brands for high-transparency, high-requirement parts, and use the off-brand for ordinary casings to balance toughening costs. Ningbo Kelong New Materials Co., Ltd. has been producing imported low-flow BR off-brands for many years, and they check gel content, Mooney viscosity, and grafting activity before the materials enter the factory.
