后备箱密封条晒三年就变硬，关不严还漏雨。后备箱密封，压变和批次没盯紧。
一句话结论：后备箱密封条，TPV 或高牌号 SEBS 基
后备箱密封条是最“省”的密封件：看不见、要求看着也不高。
但漏水一次，后备箱泡水，索赔翻倍——结论先给：预算够用 TPV；预算敏感，用高牌号 SEBS 基加耐老化体系，验收加严。
后备箱密封条的工况：长期压缩、日晒、偶尔暴雨、开关门冲击。四样加起来，材料不能软塌塌也不能发硬——硬度区间 Shore A 60-75 是主流。
一个批次三组数据：硬度、压变、老化，齐了才算验过——批次数据才是真身，牌号只是名字，拿不出随货报告的料别上车。
为什么选 TPE：免硫化加回收
后备箱密封条用 TPE 的理由：注塑/挤出直接出件，免硫化；水口可回收，利用率高；批次一致性比橡胶好——三条合起来，就是成本账。
TPE 做后备箱密封条的软肋：压变不如 TPV/EPDM。所以选型要挑体系——高牌号 SEBS 基加耐老化，或直接 TPV，按工况定价。
硬度是 TPE 的基础语言：Shore A 60-75 对应“软硬适中、关门有弹性”。硬度先定，手感才有讨论基础——硬度不对，一切都白搭。
工况拆解：压缩、日晒、水
压变是密封件的寿命表——后备箱长期处于压缩状态，TPV 压变 70℃×22h 典型 20-30%，普通 SEBS 基能到 40-50%，用久了不回弹就漏水。
日晒工况：车尾朝南，晒得最狠。老化数据（臭氧、紫外）按整车年限对齐——晒三年开裂的料，不能要。
泡水发胀、表面析出白霜，后备箱垫先烂——暴雨、洗车、涉水是常态，耐水耐水解要实测，泡水一个月数据见真章。
对比表：后备箱密封条三方案
| 方案 | 压变 | 耐候 | 成本 | 适用 |
|---|
| TPV | 20-30% | 强 | 高 | 预算够、要稳 |
| 高牌号 SEBS 基 | 30-40% | 中上 | 中 | 预算敏感、工况温和 |
| 普通 SEBS 基 | 40-50% | 中 | 低 | 短途、少雨、低要求 |
表格读法：三个方案对应三档工况。别用最低档的料做最高档的活——省下的钱，最后都还给漏水。
中间档（高牌号 SEBS 基）是大多数项目的平衡点：性能够、价格可谈。但验收要加严——压变、老化、留样一个不能少。
常见坑：批次漂移和三无料
坑一：批次漂移。同一个牌号，批次间硬度和压变飘——批次报告，比牌号名字值钱。
坑二：三无料。无批次、无报告、无留样——省钱的尽头是三无，三无的尽头是返工。
坑三：拿水口料回用不当。回收料比例失控，性能悄悄掉——回料要管着用，比例固定加验证。
三组数据写全，后备箱密封才不漏水
验收三组数据：硬度（按批次）、压变（按条件）、老化（按年限）。三组齐了，批次才算验过——三组数据，一个不能少。
批次留样要成习惯：每批留样，出争议有据可查。批次换料先对比再放量——批次稳，客诉少。
供应商问四句：什么体系、批次报告有没有、留样习惯如何、变更会不会通知。四句问完，底细清楚。
延伸判断：后备箱密封条的漏水排查，先看压变
后备箱漏水，先查压变：压变大了，密封条回弹不到位，缝隙就漏。压变数据，是漏水排查的头一站。
漏水排查要分位置：角部、拼接处、排水孔。位置不同，成因不同——分位置排查，才能定位。
漏水先查钣金配合，别先怪压变——压缩量、密封唇设计不对，压变数据再好也漏，配合不对好胶白搭。
涉水验证要实测：洗车、暴雨模拟。实测最硬——纸面不漏，实测漏，就是白搭。
后备箱密封条的成本账，算总账：单价、返工、索赔、售后。只比单价，最容易算错账——总账算清，贵料不贵。
供应商问四句：什么体系、批次报告有没有、留样习惯如何、变更会不会通知。四句问完，底细清楚——问对问题，比压价有用。
后备箱密封条的供应商，比三样：留样体系、批次数据、变更通知。三样过硬，价格才有讨论基础。
后备箱密封条的数据，要按温度读：夏天和冬天的压变不一样。按季节读数据，选型才不踩坑。
| 材料 | 压变（70℃×22h） | 耐候 | 成本 |
|---|
| TPV | 20-30% | 强 | 高 |
| SEBS 基 | 30-50% | 中 | 低 |
| EPDM | 20-40% | 强 | 中高 |
| 氯丁橡胶 | 25-40% | 中上 | 中高 |
表2读法：后备箱密封条看压变和耐候。TPV 和 EPDM 是稳妥选择——按预算和产线平衡。
| 验收项 | 方法 | 通过线 |
|---|
| 压变 | 70℃×22h 压缩 | 回弹率达标 |
| 水密 | 淋雨实测 | 无渗漏 |
| 低温 | -30℃ 弯折 | 无裂纹 |
| 批次 | 每批留样复测 | 波动在范围 |
表3读法：验收四项，一项都不能省。省了压变，就是赌漏水。
科隆客户案例：包胶件批量脱层，调参数对标复现
嘉兴一家汽车零部件厂，后备箱密封条包胶件批量脱层，返工率居高不下。科隆配合调整注塑参数（模温/料温/保压），手感回弹对标样品复现，脱层问题消失。参数对了，料才真正用得对——脱层多是工艺窗口没找准，不是料不行。
小结
后备箱密封条的材料选择，是一次判断力的练习，练多了自然就准，收藏起来备查。
The trunk seal becomes hard after three years of sun exposure, making it unable to close properly and leaking rain. The trunk seal, compression changes, and batch were not monitored closely.
One-sentence conclusion: Trunk seal strip, TPV or high-grade SEBS-based
The trunk seal is the most 'economical' sealing component: invisible and not very demanding even in appearance.
But if there is a leak even once, the trunk gets soaked, and the claim doubles — conclusion first: if the budget is sufficient, use TPV; if the budget is tight, use high-grade SEBS base with an anti-aging system, and enforce stricter acceptance criteria.
Operating conditions for the trunk seal: long-term compression, sun exposure, occasional heavy rain, and impact from opening and closing the door. Considering all four factors, the material should neither be too soft nor too hard—the mainstream hardness range is Shore A 60-75.
A batch consists of three sets of data: hardness, compression set, and aging. Only when all are complete can it be considered inspected — the batch data is the real thing, the grade is just a name. Material without accompanying reports should not be loaded onto the vehicle.
Why choose TPE: sulfur-free and recyclable
Reasons for using TPE for trunk seals: injection molding/extrusion can produce parts directly without vulcanization; sprues are recyclable, with high utilization; batch consistency is better than rubber—these three points together are a cost consideration.
The weakness of TPE for trunk seal strips: its compression set is not as good as TPV/EPDM. Therefore, when selecting a material, you need to choose the system — high-grade SEBS base for added aging resistance, or directly TPV, priced according to working conditions.
Hardness is the basic language of TPE: Shore A 60-75 corresponds to 'moderately soft and hard, with elastic closing.' Hardness must be determined first before the feel can be discussed—if the hardness is wrong, everything else is useless.
Operating condition breakdown: compression, sunlight, water
Compression set is an indicator of the lifespan of seals — the trunk is in a compressed state for a long time. TPV has a compression set of 70°C×22h typically 20-30%, while ordinary SEBS can reach 40-50%. Over time, if it doesn't rebound, it will leak.
Sun exposure conditions: the rear of the car faces south and gets the most intense sunlight. Aging data (ozone, UV) are aligned with the vehicle's service lifespan — materials that crack after three years of sun exposure are not acceptable.
Swollen from soaking, with white residue appearing on the surface, the trunk mat rots first—the normal conditions are heavy rain, car washing, and driving through water. Water resistance and hydrolysis resistance need to be tested in practice; the results after soaking for a month reveal the real performance.
Comparison Table: Three Trunk Seal Strip Solutions
| Plan | pressure transformer | weather-resistant | Cost | Applicable |
|---|
| TPV | 20-30% | Strong | Tall | Sufficient budget, needs to be stable |
| High-grade SEBS resin | 30-40% | Upper-middle | middle | Budget-sensitive, mild operating conditions |
| General SEBS base | 40-50% | middle | Low | Short distance, little rain, low requirements |
How to read the table: The three plans correspond to three levels of working conditions. Don’t use the lowest grade of material for the highest level of work—the money you save will eventually be spent on leaks.
The mid-range grade (high-grade SEBS-based) is the balance point for most projects: performance is good, and the price is negotiable. However, acceptance standards need to be stricter—compression set, aging, and sample retention are all essential.
Common pitfalls: batch drift and unverified materials
Pitfall 1: Batch drift. For the same grade, hardness and compression variation float between batches — batch reports are more valuable than the grade name.
Pitfall Two: 'Three No's' materials. No batch number, no report, no sample retained — saving money leads to 'Three No's', and the end of 'Three No's' is rework.
Pitfall 3: Improper reuse of sprue material. If the proportion of recycled material gets out of control, performance will quietly decline — recycled material must be managed during use, with fixed proportions and verification.
Write down all three sets of data, only then will the trunk seal not leak.
Acceptance of three sets of data: hardness (by batch), compression set (by condition), and aging (by duration). Only when all three sets are complete can the batch be considered tested—none of the three sets of data can be missing.
Making batch sampling a habit: sample every batch, so there is evidence to check in case of disputes. Compare before scaling up when changing materials between batches — stable batches lead to fewer customer complaints.
The supplier asks four questions: What system is in place, is there a batch report, what are the sample retention practices, and will changes be notified. After asking these four questions, the details are clear.
Extended judgment: For checking water leakage in the trunk seal, first look at the compression change
Trunk leaks, first check the pressure difference: if the pressure difference is large, the sealing strip cannot rebound properly, and gaps will leak. Pressure difference data is the first stop in leak investigation.
Leak inspection should be divided by location: corners, joints, drainage holes. Different locations have different causes—inspecting by location is the only way to pinpoint the problem.
If there is a leak, first check the sheet metal fit; don’t blame the pressure converter first—if the compression amount or sealing lip design is wrong, it will leak no matter how good the pressure converter data is, and using the right sealant is useless if the fit is wrong.
Waterproof testing requires actual measurement: car washing, simulated heavy rain. Real testing is the toughest—if it doesn't leak on paper but leaks in practice, it's all for nothing.
Cost accounting for trunk seals, calculate the general ledger: unit price, rework, claims, after-sales. Only comparing unit prices is the easiest way to make accounting mistakes — calculate the general ledger clearly, expensive materials are not costly.
The supplier asks four questions: What system is in place? Is there a batch report? What is the practice for keeping samples? Will changes be notified? After asking these four questions, the details are clear—asking the right questions is more useful than haggling over prices.
For the suppliers of trunk seals, we compare three things: sample retention system, batch data, and change notifications. Only if these three are solid can there be a basis for discussing the price.
The data for the trunk seal should be read according to temperature: the compression differs in summer and winter. Reading the data by season ensures you don't make mistakes when selecting the type.
| Material | Pressure test (70°C × 22h) | weather-resistant | Cost |
|---|
| TPV | 20-30% | Strong | Tall |
| SEBS base | 30-50% | middle | Low |
| EPDM | 20-40% | Strong | Medium-high |
| Chloroprene rubber | 25-40% | Upper-middle | Medium-high |
Reading of Table 2: Check the trunk seal for compression set and weather resistance. TPV and EPDM are safe choices — balance according to budget and production line.
| Acceptance item | Method | Through the line |
|---|
| pressure transformer | 70℃ × 22h Compression | Rebound rate meets the standard |
| Watertight | Rain test | No leakage |
| Low temperature | -30℃ bending | No cracks |
| Batch | Re-testing of each batch sample | Fluctuates within a range |
Table 3 Reading: Inspect all four items, not a single one can be skipped. Skipping the compression test is like gambling with leaks.
Cologne Customer Case: Batch Delamination of Overmolded Parts, Parameter Adjustment for Benchmark Reproduction
A car parts factory in Jiaxing experienced batch delamination of overmolded trunk seal parts, with a high rework rate. Cologne assisted in adjusting injection molding parameters (mold temperature/material temperature/holding pressure), and the tactile rebound matched the benchmark samples, resolving the delamination issue. When the parameters are correct, the material can truly be used correctly—delamination mostly occurs because the process window was not properly found, not because the material is unsuitable.
Summary
The material selection for trunk seals is an exercise in judgment; the more you practice, the more accurate you become. Keep it for reference.
