【第 1 批 · 长尾层 PP-A5】
电池模组支架隔板用什么改性PP？这篇不重复"结构件+电气安全"那套说法，改走"绝缘与耐电解液怎么验"这条主线。重点讲清 UL94 V-0、850℃ 灼热丝、RTI≥105℃ 三项电气门限的验证方法，以及电解液浸泡后绝缘与外观不劣化的判据写法，并给出验证顺序与换料风险清单。
"电池模组支架隔板用什么改性PP？"
这是我被问得最多的一类问题，但问法常常跑偏。上周一个做电池结构件的工程师发来一句："我们料过了 UL94 V0，为什么整机安规还卡住？"
我当时回了一句：你先别急着看 V0，先看绝缘和耐电解液这两关验了没有。
这句话点出了这个件最常见的失效现场——只把 V0 当成阻燃合格线，忽略了绝缘电阻的长期可靠性，以及电解液泡了半年之后材料还绝不绝得了缘。整机起火或绝缘击穿，往往不是"烧不烧得着"的问题，是"长期泡在电解液里、温度长期 80–100℃ 还能不能稳"的问题。
下面按工况、路线、判据、失效、验证五层往下拆。
一、开篇痛点：V0 过了，为什么还卡整机
这个件的失效现场，我见到最多的是三种，而且都和"只认 V0"有关。
第一种：装配后才发现绝缘电阻不够。试片测着是绝缘体，装到包里、工质一泡、热一老化，阻值往下掉，整机绝缘测试直接判不合格。
第二种：电解液泄漏点附近的支架隔板溶胀、发白、甚至开裂。问题不是强度，是介质相容性从选型阶段就没被当门限管。
第三种：灼热丝关过不了。整机安规不是只看燃烧，还要看接触热源会不会引燃——这一关往往比 V0 更晚被发现。
一句判读：电池模组支架隔板是"绝缘件 + 耐介质件 + 阻燃件"三合一，V0 只是其中一张卷子的第一题。 只验 V0，后面两关迟早爆。
二、工况六维拆解：至少三维度要写死数字
支架和隔板夹在电芯之间，工况可以拆成六个维度。把六个数报齐，方向基本就出来了。
| 维度 | 支架/隔板的实际工况 | 对材料的要求 |
|---|
| 温度 | 包内长期 80–100℃；局部热点更高；外部短路瞬间温升剧烈 | RTI ≥105℃，长期热老化不塌 |
| 载荷 | 电芯充放电膨胀的持续压力；自身重力与装配力 | 抗蠕变、尺寸稳定，不是冲击 |
| 介质 | 电解液（六氟磷酸锂有机碳酸酯体系）长期可能接触；冷却液飞溅 | 浸泡后绝缘与外观不劣化 |
| 寿命 | 整车/电池包生命周期，常见按 8–15 年设计 | 老化后性能有余量 |
| 外观 | 多数为非外观件，但要无浮纤、无开裂可视缺陷 | 表面与边缘质量 |
| 合规 | UL94 V-0、850℃ 灼热丝 30s、无卤量化定义 | 三关同时过，不互相替代 |
六个维度里，温度、介质、寿命三维度必须落进门限表，因为它们是这个件区别于普通结构件的关键。温度决定 RTI 和耐热体系；介质决定耐电解液验证要不要做；寿命决定老化余量留多少。
一个内行细节：耐电解液验证最容易被"一份 TDS 就放行"糊弄过去。TDS 上写的往往是常态性能，而支架隔板真正服役的是"85℃ 电解液 + 长期"的组合工况。同一牌号，在常温常态下绝缘好好的，泡了电解液再测可能掉一个数量级。所以耐电解液必须单独验，不能拿选型时的常态数据当长期判据。
三、材料路线对比：三条路线并列，不做谁更好的结论
改性PP 走这个件，主要有三条路线，外加和金属/工程塑料的分工边界。这里只摆拿到什么、付什么代价，不下结论。
| 路线 | 拿到的 | 付出的代价 | 适用位置 |
|---|
| 纯阻燃体系（无卤阻燃 PP） | V-0、绝缘、轻、成本低 | 刚度偏低、抗蠕变差、耐热靠基材 | 受力小的隔板、小支架 |
| 玻纤增强 + 无卤阻燃 PP | 刚度、抗蠕变、耐热同时上；可同时过 V-0、灼热丝、RTI 三关 | 各向异性、翘曲、熔接线弱、密度升 | 主承力支架、端板类 |
| 与金属/工程塑料分工 | 金属绝对刚度与耐温高；PA 类耐热与力学更好 | 金属不绝缘需加绝缘件；PA 成本高 | 极高刚度/高温位、主回路绝缘位 |
三条路线没有"谁更好"，只有分工。受力小、离电芯远的隔板，纯阻燃体系够用；要压电芯膨胀力的主支架，得上玻纤增强；绝对刚度要求极高且温度恶劣的位置，金属仍有位置。
同行抄不走的一个判断：PP 的阻燃剂加量普遍在 25–30% 这一档——"阻燃剂加得多、力学就一定掉"是 PP 的结构性问题，不是配方水平问题。这个件上要阻燃又要刚度，本质是拿玻纤去补阻燃拉掉的力学，再用结构（加强筋）去补玻纤的各向异性，是个配平游戏。
四、★ 选型判据表：五列带验证方法，每项都写清怎么验
下面这张表是全篇最该收藏的部分。注意第三列"验证方法·标准号"——选型时最常卡住的不是"看哪个指标"，而是"拿什么测、测到多少算过"。
| 指标 | 门限值（典型） | 验证方法 · 标准号 | 常见失效 | 通行解法 |
|---|
| UL94 阻燃等级 | V-0，燃烧无熔融滴落引燃周边 | UL94 垂直燃烧 | 普通磷氮阻燃料仅勉强过 V0 | 无卤阻燃体系 + 矿物填充抑制熔滴 |
| 灼热丝不引燃 | 850℃ 接触 30 s 不引燃 | GB/T 5169 系列（灼热丝） | 850℃ 关过不了 | 先保灼热丝、再保 V0 的体系顺序 |
| RTI 长期使用温度 | ≥105℃（包内长期 80–100℃） | UL 746B（RTI） | 长期热老化后性能塌 | 耐热基材 + 玻纤增强 |
| 绝缘电阻 / 电气绝缘 | 浸泡前后绝缘不劣化 | GB/T 1410 / 整机绝缘规范 | 电解液浸泡后击穿 | 本体绝缘 + 避免导电填料 |
| 耐电解液 | 见下节"项 + 变化门限 + 方法" | 电解液浸泡法（85℃） | 溶胀、开裂、绝缘降 | 耐介质基体 + 必做浸泡验证 |
| 无卤量化（溴） | <900 ppm | IEC 61249-2-21（XRF/IC） | 卤素超标 | 无卤阻燃体系 |
| 无卤量化（氯） | <900 ppm | IEC 61249-2-21（XRF/IC） | 卤素超标 | 无卤阻燃体系 |
| 溴 + 氯总和 | <1500 ppm | IEC 61249-2-21（XRF/IC） | 卤素超标 | 无卤阻燃体系 |
| GWIT 起燃温度 | 750 / 775℃ | GB/T 5169.12 | GWIT 不足 | 阻燃体系选型 |
| GWFI 燃烧指数 | 850 / 960℃ | GB/T 5169.12 | GWFI 不足 | 阻燃体系选型 |
| 弯曲模量（玻纤增强） | 按结构刚度定（示例 3000–5000 MPa） | GB/T 9341 | 刚度不足、翘曲 | 玻纤 + 加强筋 |
| 模塑收缩率 | 与模具匹配 | GB/T 17037.4 | 尺寸超差 | 玻纤含量 + 浇口设计 |
文字版结论：十二行里 灼热丝、耐电解液、无卤量化这三块最该先看，它们决定了这个件能不能进电池包；V0 反而不是最难的一关。把这张表当成体检单，缺一项不判合格，比试模试出来再回头找原因省钱得多。
耐电解液怎么验：项 + 变化门限 + 方法
这一段是贸易版完全没写的，也是本篇主线。耐电解液不能只说"耐"，得写清验什么、变多少算不过、怎么验。
| 验证项 | 变化门限（典型，以整车厂技术条件为准） | 方法 |
|---|
| 体积电阻率 / 表面电阻 | 浸泡后不得出现不可逆下降；典型判据为变化不超过一个数量级 | 浸泡于电芯电解液（六氟磷酸锂有机碳酸酯），85℃ × 规定时长，取出擦干后按 GB/T 1410 测 |
| 外观 | 不得出现裂纹、溶胀、发粘、明显变色 | 浸泡前后目视 + 放大镜比对 |
| 质量变化 | 增重不超过规定百分比（典型 ≤1%–2%，以技术条件为准） | 浸泡前后称重 |
| 尺寸变化 | 关键尺寸变化落在公差带内 | 三坐标或卡尺复测 |
| 燃烧性能余量 | 浸泡后 V-0 / 灼热丝不应明显退化 | 浸泡后复测 UL94 与灼热丝 |
文字版结论：耐电解液验证的核心是"泡了之后再测"，不是"选型时看一眼 TDS"。最容易踩的坑是只验常态绝缘，没验浸泡后绝缘——而支架隔板真正服役的就是浸泡工况。门限数字各家不同，所以写法固定为"项 + 变化门限 + 方法"，拿去和整车厂技术条件对齐即可。
五、常见失效与根因：四个现象，四条根因
失效一：整机绝缘测试不合格，但试片是好的。 根因多半是"没验浸泡后绝缘"——常态绝缘靠 PP 本体就够，泡了电解液、受了热老化之后阻值掉下来。先查有没有做耐电解液浸泡验证，再查有没有用导电填料。
失效二：电解液接触处溶胀、发白、开裂。 根因是介质相容性没进门限。支架隔板离电芯近，泄漏风险点必须单独验耐电解液，不能只验常态力学。
失效三：灼热丝关过不了。 根因常是体系顺序排反了——先保 V0、后保灼热丝，结果灼热丝 850℃ 接触 30s 起燃。正确顺序是先保灼热丝再保 V0。
失效四：玻纤料翘曲、熔接线断。 根因在结构与成型，不在料"不好"。各向异性靠玻纤含量和浇口控制，熔接线弱靠件设计和工艺。
敢否定一个常见做法：很多人选型时把"绝缘"等同于"过了 UL94 V0"。这是错的。V0 问的是"烧起来会不会蔓延"，绝缘问的是"长期泡介质还绝不绝得了缘"，灼热丝问的是"碰热源点不点得着"——三件事互不替代。只拿 V0 当绝缘合格证的，迟早卡整机安规。
六、验证顺序：先验什么，后验什么，不过就退回
这一段同行几乎没人写，但它是换料能不能省钱的关键。顺序错了，成本会在最后一步集中爆出来。
`
① 小样物理比对 拉伸 / 弯曲 / 缺口冲击 / 收缩率 / 常态绝缘 / 阻燃初筛
↓ 六项都在门限内，才往下走
② 耐电解液浸泡验证 85℃ 电解液浸泡后测绝缘 + 外观 + 尺寸
↓ 这一关不过，后面全部不用做（介质不相容，改基体）
③ 灼热丝 + RTI 验证 850℃/30s 不引燃；RTI ≥105℃
↓ 不过则退回重排阻燃体系（先灼热丝后 V0）
④ 短射试模 看充填是否完整、熔接线在哪、有没有浮纤
↓ 短射走通，才谈批量
⑤ 装车匹配 + 批量 间隙、绝缘实测、批次一致性
↓
⑥ 客户端长期验证
`
文字版结论：验证顺序是 小样 → 耐电解液 → 灼热丝/RTI → 短射 → 装车。耐电解液和灼热丝这两关必须放在试模之前过，因为它们是最可能一票否决、且改起来最贵的项；过了它们再做模具侧的事，才不会白花试模费。
七、反向诚实：这三个情况，这个件不该用改性PP
前面讲"怎么做"，这里讲"什么时候别做"。这一段对选型判断的价值最高。
| 出现的情况 | 为什么改性PP不合适 | 该往哪走 |
|---|
| 长期工作温度 150℃ 以上 | PP 负荷变形温度上限就在那条线，填充增强往上抬也有边界 | 换更高耐热的工程塑料或专用材料体系 |
| 要求金属级导热 / 电磁屏蔽 | PP 是绝热绝缘体，加导热/屏蔽填料会伤绝缘与阻燃 | 金属，或专用导热/屏蔽材料 |
| 高压主回路承压绝缘、极高长期绝缘可靠性 | 本体绝缘有余量，但长期耐压可靠性需专业绝缘结构保障 | 工程塑料绝缘件或专用绝缘结构件 |
| 绝对刚度要求极高且温度恶劣 | 塑料靠结构补刚度，材料本身模量有限 | 金属方案 |
规律是一致的：只要出现"长期高温 + 高可靠绝缘 + 高刚度"叠加，就说明这个件不该用 PP 硬撑。 遇到这种需求，先说清楚再谈折中——硬接下来的单子，最后都要用返工和索赔还回去。
八、换料要动什么：一张先看再动的清单
决定试改性PP之前，这张表建议先过一遍。客户真正的顾虑往往不是性能，是"我现在的模具和工艺要不要改"。
| 要动的项 | 需要确认什么 | 不做会怎样 |
|---|
| 模具收缩率 | 新料收缩率与原方案的差，长件上尤其敏感 | 尺寸超差，装车间隙对不上 |
| 浇口与排气 | 玻纤料流动差异是否需要改浇口位置 | 充填不足、熔接线位置变化 |
| 料温与模温 | 阻燃玻纤料与原有体系的窗口不同 | 表面浮纤、熔接线强度不够 |
| 干燥 | 填充/玻纤体系按具体牌号定 | 气泡、银丝 |
| 保压与脱模 | 收缩差异带来变形与顶白 | 变形、顶出拉伤 |
| 色差 | 非外观件也要先确认批次一致性 | 批次色差争议 |
| 验证顺序 | 小样 → 耐电解液 → 灼热丝/RTI → 短射 → 装车 | 风险全部压到最后一步集中爆发 |
文字版结论：换料要动的是模具、工艺、色差三块，其中最该先谈的是验证顺序。跳过小样直接试模，等于把成本提前花出去；跳过短射直接批量，一次失败就是整批损失。
九、一页纸汇报对照表（可以直接贴进 PPT）
| 场景 | 推荐路线 | 关键指标 | 验证标准 | 需先确认的条件 |
|---|
| 常规模组支架（离电芯较远） | 无卤阻燃 PP（必要时少量玻纤） | V-0；850℃ 灼热丝 30s；RTI≥105℃ | UL94、GB/T 5169、UL 746B | 受力大小、是否近泄漏点 |
| 模组隔板（近电芯） | 无卤阻燃 PP + 耐介质基体 | 耐电解液浸泡后绝缘不降；无卤量化 | 电解液浸泡法、IEC 61249-2-21 | 电解液体系、浸泡温度时长 |
| 主承力支架 / 端板 | 玻纤增强 + 无卤阻燃 PP | 弯曲模量按刚度定；抗蠕变；三关同过 | GB/T 9341 + UL94 + 灼热丝 | 膨胀力、尺寸链、翘曲容差 |
| 轻量上盖替代金属 | 玻纤增强 + 无卤阻燃 PP | 减重；V-0；RTI≥105℃ | UL94、UL 746B | 是否重新做结构设计 |
文字版结论：这张表的作用是让技术员把结论直接往上报，不必重新组织语言。判断标准只有一条——客户拿这张表，能不能在一次会议里把材料方向定下来。
十、这个件上最容易出问题的，往往不是料
电池模组支架隔板行业最常见的认知偏差，是把"绝缘"等同于"过了 UL94 V0"。公开资料反复提到三点共识：一是 UL94 V-0、850℃ 灼热丝、RTI 三者考察维度不同、互不替代，只过 V0 不足以覆盖整机其余条款；二是耐电解液必须单独验，常态绝缘好的料泡了电解液再测可能掉一个数量级；三是无卤有明确的量化定义——溴 <900 ppm、氯 <900 ppm、两者总和 <1500 ppm，灼热丝指标 GWIT 750/775℃、GWFI 850/960℃。这三点在公开资料中有共识，但落到询盘里，"过了 V0 为什么还不行"仍然是最常见的问题。
公开的判据按这些口径走：燃烧性能按 UL94（垂直燃烧，含是否引燃周边）；灼热丝按 GB/T 5169 系列评价（常见 850℃ 级别、接触 30s 不引燃）；长期耐热按 RTI 口径（≥105℃）；耐电解液按电解液浸泡后测绝缘与外观的方法；无卤按 IEC 61249-2-21 量化。力学性能按 GB/T 1043.1、GB/T 1040.2、GB/T 9341；绝缘电阻按 GB/T 1410。这些都是口径，具体门槛值以整车厂技术条件与安全规范为准。
行业通行的解法是：阻燃体系按"先保灼热丝、再保 V0"的顺序选型；耐电解液通过浸泡验证单独把关；刚度走适量玻纤加结构加强筋的组合，而不是把玻纤拉满；收缩与翘曲通过玻纤含量控制与浇口设计改善；绝缘性能靠 PP 本体达成，避免过多导电性填料。
宁波市科隆新材料有限公司在这个件上常供的是改性PP 粒子里的无卤阻燃增强方向：按支架还是隔板、近不近电芯、要不要压膨胀力三个工况给到对应的基材档位与阻燃/玻纤/增韧配平，主要用来解决上面说的"只过 V0 却卡整机安规"和"没验浸泡后绝缘"这两件事；配方按件的工况调，可以配合做小样比对、耐电解液浸泡验证与试模，件级客户多品种小批量的需求也能接。
常见问答
问：无卤怎么证明？
答：无卤不是形容词，是有量化线的——溴 <900 ppm、氯 <900 ppm、两者总和 <1500 ppm，按 IEC 61249-2-21 用 XRF/IC 测。要供应商给这份检测，比听一句"我们是无卤的"有用。
问：耐电解液验证要做到什么程度？
答：至少做"泡了之后再测"——浸泡于电芯电解液、85℃、规定时长，取出擦干后测体积电阻率、外观、质量与尺寸变化。门限数字各家不同，写法是固定的"项 + 变化门限 + 方法"，拿去和整车厂技术条件对齐即可。
| 工况 | 关键判据 | 本厂常规供应 |
|---|
| 常规模组支架 | V-0；850℃ 灼热丝 30s；RTI≥105℃ | 无卤阻燃改性PP 方向 |
| 近电芯隔板 | 耐电解液浸泡后绝缘不降；无卤量化 | 无卤阻燃 + 耐介质基体方向 |
| 主承力支架 | 弯曲模量按刚度定；抗蠕变；三关同过 | 玻纤增强 + 无卤阻燃方向 |
想提醒一句：件出问题，最常见的错法是先换料。绝缘降、溶胀、翘曲——每一条的原因都不止一个。先定位，再换料；顺序反了，往往换了几轮还在原地。
写在最后
第一，V0 只是绝缘件的一张卷子的第一题。 灼热丝、耐电解液、RTI 才是这个件真正的三道关，而且互不替代。
第二，耐电解液必须单独验，不能拿选型时的常态数据当长期判据。 写法是固定的"项 + 变化门限 + 方法"，泡了之后再测才是真服役工况。
第三，验证顺序比验证项更贵。 小样 → 耐电解液 → 灼热丝/RTI → 短射 → 装车，前两关必须放在试模之前过。
下一篇讲电池包上盖——那个件更看重减重与整体阻燃，逻辑和支架隔板又有不同。
关于我们
同一个牌号，两家做出来不一样，问题出在哪？
料是同一个料，工艺是两套工艺。干燥、模温、螺杆、浇口位置，任意一项偏了，出来就是两个件。选料选对了只算赢了一半。
宁波市科隆新材料有限公司，自产改性聚丙烯（PP）造粒，覆盖均聚 / 无规共聚 / 抗冲共聚三档基材，以及填充、玻纤增强、增韧、阻燃、低气味低 VOC、耐候、免喷涂耐划伤等改性方向；兼营各大石化厂 PP 树脂、副牌料与大包料。
【Batch 1 · Long Tail Layer PP-A5】
What type of modified PP is used for battery module support brackets and partitions? This article should not repeat the 'structural components, electrical safety' approach, but should follow the main line of 'how to verify insulation and electrolyte resistance.' Focus on clearly explaining the verification methods for the three electrical thresholds: UL94 V-0, 850°C glow wire, and RTI≥105°C. Also, provide guidance on writing criteria for insulation and appearance non-degradation after electrolyte immersion, as well as the sequence of verification and a checklist of material change risks.
What type of modified PP is used for battery module bracket separators?
This is the type of question I get asked the most, but the way it’s asked often goes off track. Last week, an engineer working on battery structural components sent me a message saying: 'We passed the UL94 V0 material test, so why is the whole device still stuck on safety certification?'
I replied at the time: Don’t rush to look at V0, first check whether the insulation and electrolyte resistance tests have been passed.
This sentence points out the most common failure scenario for this component — treating V0 merely as a pass mark for flame retardancy while neglecting the long-term reliability of insulation resistance, as well as whether the material can still survive after being immersed in electrolyte for half a year. The entire device catching fire or experiencing insulation breakdown is often not an issue of 'whether it can burn or not,' but 'whether it can remain stable after being soaked in electrolyte at 80–100°C for a long time.'
Below, we break down step by step according to five layers: operating conditions, route, criteria, failure, and verification.
1. Opening Pain Point: V0 is over, so why is the whole machine still lagging?
At the failure site of this component, I have seen mostly three types, and all are related to 'only recognizing V0'.
The first type: discovering insufficient insulation resistance only after assembly. The test piece shows it is an insulator, but after being installed in the package, exposed to the working medium, and subjected to heat aging, the resistance value drops, and the insulation test of the complete machine directly fails.
The second type: the support baffles near the electrolyte leakage point swell, turn white, or even crack. The problem is not strength; it’s that the dielectric compatibility was not considered as a threshold during the selection stage.
The third type: the hot wire test cannot be passed. The overall safety standard of the device is not only about combustion; it also needs to consider whether contact with a heat source will cause ignition — this issue is often discovered later than V0.
A judgment in one sentence: The battery module bracket separator is a 'three-in-one' of insulating part, dielectric-resistant part, and flame-retardant part. V0 is just the first question on one of the sheets. If you only test V0, the latter two checkpoints will eventually fail.
2. Six-dimensional breakdown of working conditions: at least three dimensions must have fixed numbers
The brackets and spacers are clamped between the battery cells, and the working condition can be divided into six dimensions. Once the six numbers are reported, the direction basically comes out.
| Dimension | Actual working conditions of the bracket/divider | Requirements for the materials |
|---|
| Temperature | Long-term inside the package 80–100°C; local hotspots even higher; external short-circuit causes a sharp instantaneous temperature rise | RTI ≥105℃, does not collapse under long-term thermal aging |
| Load | The continuous pressure from the expansion of the battery cell during charging and discharging; self-weight and assembly force | Creep-resistant and dimensionally stable, not impact-resistant |
| Medium | Electrolyte (lithium hexafluorophosphate organic carbonate system) may be contacted for a long time; coolant splashing | No deterioration in insulation and appearance after soaking |
| Lifespan | The vehicle/battery pack lifecycle is commonly designed for 8–15 years | Performance margin after aging |
| Appearance | Mostly non-visible parts, but must have no floating fibers or visible defects such as cracks | Surface and edge quality |
| Compliance | UL94 V-0, 850℃ glowing wire 30s, halogen-free quantitative definition | Pass all three checkpoints at the same time, without substituting for each other |
Among the six dimensions, temperature, medium, and lifespan must fall into the threshold table because they are the key aspects that distinguish this part from ordinary structural parts. Temperature determines the RTI and heat-resistant system; the medium determines whether the electrolytic solution resistance verification needs to be done; lifespan determines how much aging margin to leave.
A professional detail: Electrolyte resistance testing is most easily fooled by being 'approved with just a TDS'. What is usually written on the TDS is normal performance, whereas the actual service condition for the support separator is 'long-term at 85°C in electrolyte'. The same grade may have good insulation under normal conditions at room temperature, but after soaking in electrolyte, the measurement could drop by an order of magnitude. Therefore, electrolyte resistance must be tested separately and normal data from selection cannot be used as a criterion for long-term performance.
3. Comparison of material routes: Three routes are presented side by side, without concluding which is better.
Modified PP follows this item, mainly through three routes, plus the division of labor boundary with metals/engineering plastics. Here we only list what can be obtained and at what cost, without drawing conclusions.
| Route | obtained | The price paid | Applicable Location |
|---|
| Pure flame-retardant system (halogen-free flame-retardant PP) | V-0, insulated, light, low cost | Low stiffness, poor creep resistance, heat resistance depends on the substrate | Partitions and small brackets with low stress |
| Glass Fiber Reinforced Halogen-Free Flame Retardant PP | Stiffness, creep resistance, and heat resistance are all improved; can simultaneously pass V-0, glow wire, and RTI tests | Anisotropy, warping, weak weld lines, increased density | Main load-bearing bracket, end plate type |
| Division of labor with metals/engineering plastics | Metal has absolutely high stiffness and temperature resistance; PA types have better heat resistance and mechanical properties | Metal is not insulated and requires adding insulating parts; PA is expensive | Extremely high stiffness/high temperature position, main circuit insulation position |
There is no 'which is better' among the three routes, only division of labor. For the partitions that experience low stress and are far from the battery cells, a purely flame-retardant system is sufficient; for the main supports that need to withstand the expansion force of the battery cells, fiberglass reinforcement is required; for positions where absolute rigidity is extremely high and the temperature is harsh, metal still has its place.
A judgment that peers cannot copy: the amount of flame retardant added to PP generally falls in the 25–30% range—'the more flame retardant, the lower the mechanical properties' is a structural problem of PP, not a formulation-level problem. For this part, requiring both flame retardancy and stiffness essentially means using glass fiber to compensate for the mechanical loss caused by the flame retardant, and then using structure (reinforcements) to compensate for the anisotropy of the glass fiber—it's a balancing game.
4. ★ Selection Criteria Table: Five columns with verification methods, each item clearly describes how to verify
The table below is the part of the entire text that is most worth saving. Pay attention to the third column 'Verification Method·Standard Number' — the part that most often gets stuck during selection is not 'which indicator to look at,' but 'what to measure with, and how much counts as passing'.
| Indicator | Threshold (typical) | Verification Method · Standard Number | Common Failures | Common solution |
|---|
| UL94 Flammability Rating | V-0, burns without molten droplet, does not ignite surrounding materials | UL94 Vertical Burning | Ordinary phosphorus-nitrogen flame retardants barely pass V0 | Halogen-free flame retardant system Mineral-filled to inhibit molten droplets |
| The glowing wire does not ignite | 850℃ contact for 30 s does not ignite | GB/T 5169 Series (Glow Wire) | Cannot pass 850℃ | First preserve the incandescent wire, then preserve the V0 system sequence |
| RTI long-term use temperature | ≥105℃ (long-term 80–100℃ inside the package) | UL 746B (RTI) | Performance collapses after long-term thermal aging | Heat-resistant substrate Glass fiber reinforced |
| Insulation Resistance / Electrical Insulation | Insulation does not deteriorate before and after soaking | GB/T 1410 / Complete Machine Insulation Specification | Breakdown after electrolyte immersion | Intrinsic insulation Avoid conductive fillers |
| Electrolyte-resistant | 'See next section' item Change threshold Method | Electrolyte Soaking Method (85℃) | Swelling, cracking, insulation degradation | Media-resistant substrate Soaking validation must be performed |
| Halogen-free quantification (bromine) | <900 ppm | IEC 61249-2-21 (XRF/IC) | Excessive halogens | Halogen-free flame retardant system |
| Halogen-free quantification (chlorine) | <900 ppm | IEC 61249-2-21 (XRF/IC) | Excess halogen | Halogen-free flame retardant system |
| Total Bromine and Chlorine | <1500 ppm | IEC 61249-2-21 (XRF/IC) | Excess halogen | Halogen-free flame retardant system |
| GWIT Ignition Temperature | 750 / 775℃ | GB/T 5169.12 | GWIT insufficient | Flame Retardant System Selection |
| GWFI Combustion Index | 850 / 960℃ | GB/T 5169.12 | GWFI insufficient | Flame Retardant System Selection |
| Flexural Modulus (Glass Fiber Reinforced) | Determined by structural stiffness (example 3000–5000 MPa) | GB/T 9341 | Insufficient stiffness, warping | Fiberglass Reinforcement rib |
| Molding shrinkage rate | Match with the mold | GB/T 17037.4 | Size out of tolerance | Glass fiber content Gate design |
Text version conclusion: Among the twelve items, the three areas to check first are hot wire, electrolyte resistance, and halogen-free quantification, as they determine whether this component can go into the battery pack; V0, on the other hand, is not the hardest hurdle. Consider this table as a health check-up form; if any item is missing, do not deem it qualified. It's much more cost-effective to test with the mold first and then go back to find the reasons.
How to test electrolyte resistance: Item Threshold change Method
This section is completely missing from the trade version, and it is also the main storyline of this article. Electrolyte resistance cannot just be described as 'resistant'; it must specify what is being tested, how much change is considered failing, and how it is tested.
| Verification item | Change threshold (typical, subject to the technical conditions of the vehicle manufacturer) | Method |
|---|
| Volume resistivity / Surface resistivity | No irreversible decline should occur after soaking; a typical criterion is that the change does not exceed one order of magnitude. | Soak in the battery cell electrolyte (lithium hexafluorophosphate in organic carbonates), 85℃ × specified duration, then remove and wipe dry before testing according to GB/T 1410 |
| Appearance | There must be no cracks, swelling, stickiness, or obvious discoloration. | Visual inspection before and after soaking Comparison with magnifying glass |
| Quality change | Weight increase does not exceed the specified percentage (typically ≤1%–2%, according to technical specifications) | Weigh before and after soaking |
| Dimensional change | The key dimensional changes fall within the tolerance range | Re-measure with coordinate measuring machine or caliper |
| Combustion Performance Margin | After soaking, V-0 / glowing wire should not show significant degradation | Retest UL94 and glowing wire after soaking |
Text version conclusion: The core of electrolyte resistance verification is 'test after soaking,' not 'glance at TDS when selecting the model.' The most common pitfall is only testing the normal insulation and not testing the insulation after soaking—whereas the brackets and spacers actually serve in soaked conditions. Each company's threshold numbers are different, so the format is fixed as 'Item Threshold Change Method,' which can be aligned with the vehicle manufacturer's technical specifications.
5. Common Failures and Root Causes: Four Phenomena, Four Root Causes
Failure 1: The overall machine insulation test fails, but the test specimens are fine. The root cause is most likely 'no inspection of insulation after soaking'—normal insulation is sufficient with just the PP body, but after being soaked in electrolyte and experiencing thermal aging, the resistance drops. First, check whether resistance to electrolyte soaking was verified, and then check whether conductive fillers were used.
Failure 2: Swelling, whitening, and cracking at the electrolyte contact points. The root cause is that the medium compatibility did not meet the threshold. Since the bracket and separator are close to the cell, the leakage risk points must be specifically tested for electrolyte resistance and cannot rely solely on standard mechanical testing.
Failure 3: The hot wire keeps failing. The root cause is often that the system sequence is reversed — first maintaining V0, then the hot wire, resulting in the hot wire igniting at 850℃ after 30 seconds of contact. The correct sequence is to maintain the hot wire first, then V0.
Failure 4: Warping of fiberglass material and weld line breakage. The root cause lies in the structure and molding, not in the material being 'bad.' Anisotropy is controlled by the fiberglass content and gate design, while weld line weakness depends on part design and process.
Can we deny a common practice: Many people equate 'insulation' with 'meeting UL94 V0' when selecting components. This is wrong. V0 addresses 'will it spread if it catches fire,' insulation addresses 'can it still insulate after long-term exposure to the medium,' and the glow-wire test addresses 'does it ignite when touching a heat source'—the three are not interchangeable. Relying solely on V0 as proof of insulation qualification will sooner or later cause problems with overall equipment safety compliance.
6. Verification sequence: what is a priori, what is a posteriori, it just returns.
Almost no one in the industry writes this part, but it is the key to whether material changes can save money. If the order is wrong, the costs will concentrate and explode at the final step.
`
① Sample physical comparison: tensile / bending / notch impact / shrinkage / normal insulation / preliminary flame retardant screening
↓ Only if all six items are within the threshold, proceed further
② Electrolyte Immersion Test: Measure insulation, appearance, and dimensions after immersion in electrolyte at 85°C
↓ If you can't pass this stage, you don't need to do the rest (incompatible medium, change the base material)
③ Glowing wire RTI test 850℃/30s does not ignite; RTI ≥105℃
↓ Otherwise, go back to rearranging the flame-retardant system (first the hot wire, then V0)
④ Short shot test mold: Check whether the filling is complete, where the weld lines are, and if there are floating fibers
↓ Only after the short-range shot works can we talk about mass production
⑤ Truck Loading Matching Batch Gap, Insulation Measurement, Batch Consistency
↓
⑥ Client Long-Term Authentication
`
Text version of the conclusion: The verification sequence is Sample → Electrolyte Resistance → Glow Wire/RTI → Short Shot → Assembly. The Electrolyte Resistance and Glow Wire stages must be completed before the mold trial, because they are the items most likely to be outright rejected and are the most expensive to modify; only after passing them should the mold-related work be done, so that the mold trial costs are not wasted.
7. Reverse honesty: In these three situations, this part should not use modified PP.
Earlier we talked about 'how to do it'; here we talk about 'when not to do it.' This section has the highest value for selection and judgment.
| The situation that occurred | Why is modified PP not suitable | Which way should I go? |
|---|
| Long-term working temperature above 150℃ | The upper limit of the PP deformation temperature under load is on that line, and adding fillers to reinforce it can also raise it within certain boundaries. | Switch to higher heat-resistant engineering plastics or specialized material systems |
| Requires metal-grade thermal conductivity / electromagnetic shielding | PP is an adiabatic insulator; adding thermal conductivity/shielding fillers will damage insulation and flame retardancy | Metal, or specialized thermal/conductive shielding materials |
| High-voltage main circuit pressure-bearing insulation, extremely high long-term insulation reliability | The insulation of the body has a margin, but long-term voltage withstand reliability requires professional insulation structure assurance. | Engineering plastic insulating parts or special insulating structural parts |
| Requires extremely high absolute stiffness and harsh temperatures | Plastic relies on its structure to compensate for stiffness, as the material itself has a limited modulus. | Metal plan |
The pattern is consistent: whenever 'long-term high temperature, high reliability insulation, high stiffness' occur together, it indicates that this part should not use PP for rigid support. When encountering such a requirement, clarify it first before discussing compromises—rigidly handling these orders will ultimately require rework and claims to be returned.
8. What to Move When Changing Materials: A Checklist to Review Before Taking Action
Before deciding to try modifying PP, it is recommended to go through this table first. The customer's real concern is often not performance, but 'whether I need to change my current mold and process'.
| Items to move | What needs to be confirmed | What will happen if I don't do it? |
|---|
| Mold shrinkage rate | The difference in shrinkage rate of the new material compared to the original plan is particularly sensitive in long parts | The dimensions are off, and the clearance during loading doesn't match. |
| Gate and Venting | Does the difference in fiberglass material flow require changing the gate position? | Insufficient filling, change in weld line position |
| Material Temperature and Mold Temperature | The flame-retardant fiberglass material has a different window from the original system | Surface floating fibers, insufficient splice strength |
| Dry | The filler/glass fiber system is determined according to the specific grade | Bubbles, silver threads |
| Pressure Holding and Demolding | Shrinkage differences cause deformation and whitening on the surface | Deformation, extrusion strain |
| Color difference | Non-exterior parts also need to confirm batch consistency first | Batch color difference dispute |
| Verification order | Sample → Electrolyte resistance → Hot wire/RTI → Short shot → Loading | All the risks are concentrated to explode at the final step |
Text version conclusion: Material change involves three parts: mold, process, and color difference, with the verification sequence being the most important to discuss. Skipping samples and going straight to mold trial means spending costs in advance; Skipping short firing and going straight to batch production means one failure means a loss for the entire batch.
9. One-page report comparison table (can be directly pasted into PPT)
| Scene | Recommended Route | Key indicators | Verification Standard | Conditions that need to be confirmed first |
|---|
| Standard module bracket (far from the battery cell) | Halogen-free flame-retardant PP (with a small amount of glass fiber if necessary) | V-0; 850℃ glowing wire for 30s; RTI ≥ 105℃ | UL94, GB/T 5169, UL 746B | Magnitude of force, whether near the leak point |
| Module partition (near the cell) | Halogen-free flame-retardant PP Media-resistant matrix | Insulation does not degrade after electrolyte immersion; halogen-free quantified | Electrolyte soaking method, IEC 61249-2-21 | Electrolyte system, soaking temperature and duration |
| Main load-bearing bracket / end plate | Glass Fiber Reinforced Halogen-Free Flame Retardant PP | Bending modulus is determined by stiffness; creep resistance; all three gates pass together | GB/T 9341 UL94 Glow Wire | Expansion force, dimensional chain, warpage tolerance |
| Lightweight top cover replaces metal | Glass fiber reinforced halogen-free flame retardant PP | Weight loss; V-0; RTI ≥ 105℃ | UL94, UL 746B | Whether to redo the structural design |
Text version conclusion: The purpose of this table is for the technicians to report the conclusions directly, without having to reorganize the wording. There is only one criterion for judgment — whether the customer can use this table to finalize the direction of the materials in a single meeting.
10. The part of this item that is most prone to problems is often not the material.
The most common misconception in the battery module bracket and spacer industry is equating 'insulation' with 'having passed UL94 V0.' Public information repeatedly mentions three points of consensus: first, UL94 V-0, 850°C glow wire, and RTI assess different dimensions and are not interchangeable; passing V0 alone is insufficient to cover the other requirements of the entire device. Second, electrolyte resistance must be tested separately; materials that normally have good insulation can drop by an order of magnitude after being soaked in electrolyte. Third, halogen-free has a clear quantitative definition—bromine <900 ppm, chlorine <900 ppm, and the sum of the two <1500 ppm, with glow wire indicators GWIT 750/775°C and GWFI 850/960°C. These three points are agreed upon in public information, yet in inquiries, the most common question remains: 'Why is it still not acceptable even after passing V0?'
published standards follow these standards: combustion performance according to UL94 (vertical combustion, including ignition of surrounding areas); Glow-heat wire evaluated according to GB/T 5169 series (commonly 850°C, does not ignite after 30 seconds of contact); Long-term heat resistance is evaluated according to RTI caliber (≥105°C); Electrolyte resistance is measured by insulation and appearance after immersion in electrolyte; Halogen-free is quantified according to IEC 61249-2-21. Mechanical properties are according to GB/T 1043.1, GB/T 1040.2, GB/T 9341; Insulation resistance is based on GB/T 1410. These are all diameters; specific threshold values depend on the automaker's technical conditions and safety standards.
's industry-common solution is: the flame-retardant system should be selected in the order of "preserving the hot wire, then V0"; Electrolyte resistance is independently verified through immersion; Stiffness should be a combination of appropriate glass fiber and structural reinforcement ribs, rather than overstretching the fiberglass; Shrinkage and warping are improved through glass fiber content control and gate design; Insulation performance is achieved through the PP body, avoiding excessive conductive fillers.
Ningbo Kelong New Materials Co., Ltd. commonly supplies halogen-free flame-retardant enhancement directions for modified PP pellets: based on bracket or partition, cell proximity, and compression expansion force required, corresponding substrate levels and flame-retardant/fiberglass/toughening balance. This mainly addresses the two issues mentioned above: "only passing V0 but still stuck with overall machine safety standards" and "insulation after immersion without testing." The formula is adjusted according to the part's operating conditions, can be combined with sample comparison, electrolyte soaking resistance verification and mold trials, and can accommodate small-batch multi-variety and small-batch needs from part-level customers.
FAQ
Q: How to prove halogen-free?
A: Halogen-free is not an adjective; it has quantification lines—bromine <900 ppm, chlorine <900 ppm, total <1500 ppm, measured according to IEC 61249-2-21 using XRF/IC. Getting the supplier to provide this test is more useful than simply saying, "We are halogen-free."
Q: What level of electrolyte resistance verification should be done?
A: At least "soak before testing"—soak in battery cell electrolyte at 85°C for the specified time, then remove and dry to measure volumetric resistivity, appearance, mass, and dimensional changes. Threshold numbers vary by manufacturer; the fixed format is "item + variation threshold + method," which can be aligned with the automaker's technical specifications.
| Operating Condition | Key Criteria | Factory's Conventional Supply |
|---|
| Normal Scale Group Support | V-0; 850°C Hot Wire 30s; RTI≥105°C | Halogen-Free Flame-Retardant Modified PP Direction /Direction |
| Near Battery Cell Separator | Resistant Insulation Does Not Decrease After Electrolyte Soaking; Halogen-free quantization | Halogen-free flame retardant + dielectric-resistant substrate direction |
| Main load-bearing bracket | Flexural modulus determined by stiffness; Creep resistance; All three tests passed simultaneously | Glass fiber reinforcement + halogen-free flame-retardant direction |
Just a reminder: When a part has a problem, the most common mistake is to change the material first. Insulation degradation, swelling, warping—each one has more than one cause. Position first, then change the material; If the order is reversed, you often end up in the same place after several rounds of replacement.
Final Notes
First, V0 is just the first question on the insulating parts paper. Hot wire, electrolyte-resistant solution, and RTI are the real three key points for this part, and they are irreplaceable.
Second, electrolyte-resistant solvent must be tested separately; you can't use normal data from selection as a long-term criterion. The format is fixed "term + threshold of change + method"; only after soaking before testing is the real service condition.
Third, the validation sequence is more expensive than the validation items. Sample → electrolyte-resistant → hot wire/RTI → short shot → loading; the first two checkpoints must be passed before mold trial.
Next article will talk about the battery pack cover—which one focuses more on weight reduction and overall flame retardancy, but the logic and bracket partition are different.
About Us
Same grade, but the two companies make them differently. What's the problem?
is the same material, but the process is two sets. Drying, mold temperature, screw, gate position—if any one is off, it results in two parts. Choosing the right material only means half the win.
Ningbo Kelong New Materials Co., Ltd. produces modified polypropylene (PP) pelletizing and covers three levels of substrates: homopolymer, random copolymer, and impact-resistant copolymer, as well as modification directions such as filling, glass fiber reinforcement, toughening, flame retardancy, low odor and low VOC, weather resistance, and scratch-resistant coating. Also operates PP resin, sub-brand materials, and large package materials for major petrochemical plants
