运动器材握把与护具用改性PP 加 SEBS / TPE 发泡，判据不是"软不软"，是"受过多少次冲击还能吸多少"。这篇把护具的大冲击与握把的小能量拆成两条失效路径，讲清泡孔塌陷的机理、人工汗液浸泡后的止滑复测、七项判据与验证顺序，并说明哪几种情况下这个件不该用 PP 基软层。
- 总纲：→《改性PP能用在哪些产品上？十大领域 88 个件的用材地图》（PP-A0）
"握把用了两个月，手感还在，可一出手汗就打滑，越打越不敢发力。"
"护膝头一次摔下去挺顶用，再摔两次，膝盖还是磕青了——同一个护具、同一个位置。"
说这两句话的，一个做球拍配件，一个做护具代工。放在一篇里讲，是因为它们指向同一件事：
运动件上的软层是"吸能层"，不是"舒适层"。它的判据是"受过多少次冲击还能吸多少"，不是"软不软"。
硬度只决定压下去的手感。决定这个件还能不能用的，是泡孔还在不在、还能不能继续塌陷吸能。用改性PP 做这个软层的载体，最容易走偏的一步就在这里。
一、工况六维拆解：护具是大冲击少次数，握把是小能量多次数
先说结论：这两类件开头该问的不是"多少度软"，而是"这个软层要挨多少次、每次多大力"。
▸ 护具（护膝、护肘、护腕）——单次能量大、次数少：冲击试验按 50 J 量级设计，一个赛季也只挨几十到上百次；判据是单次峰值能不能削平、挨完还剩多少吸能。
▸ 握把（球拍、球杆、骑行把套）——单次能量极小、次数极多：一次握持几百牛的力，但一天几千次、一年几百小时；判据是长期循环后厚度、回弹与止滑还剩多少。
把六个维度摆在一起看：
| 维度 | 实际工况 | 对材料的要求 |
|---|
| 温度 | 夏季户外 40-60℃；冬季户外 -20~-10℃；汗液本体约 37℃ | 低温不发硬脆、高温不软化，两态都复测吸能 |
| 载荷 | 护具单次大冲击（50 J 量级）；握把反复握压（单次数百牛，一天数千次） | 护具看峰值削平与多次冲击保持；握把看长期压缩后的厚度与回弹 |
| 介质 | 汗液（盐、乳酸、尿素）、皮脂、防晒霜与驱蚊液（含酒精与有机溶剂）、余氯 | 不发粘、不鼓包、不剥离、不变色，湿态摩擦保持 |
| 寿命 | 护具按赛季（几十到上百次冲击）；握把按使用小时（一年数百小时） | 冲击后的吸能保持率；长期压缩后的回弹保持 |
| 外观 | 深色软层在浅色衣物上留印；户外件耐 UV 后发黄、粉化 | 沾色级数、老化后色差 |
| 合规 | 长期贴肤、护具出口走 EN 1621 体系、抗菌客观表述、气味 | 色牢度与迁移、气味口径、抗菌按标准做 |
六维里只有两维是一票否决性质的：冲击后的吸能保持，和汗液后的止滑保持。 其他维度出问题最多是体验差、返工；这两条，一条关系到护具还能不能护，一条关系到握把会不会脱手。
一个内行细节：发泡软层试样，生产后不足 72 小时一般不能做压缩永久变形试验，试验前还要状态调节 16 小时以上（GB/T 6669-2008 / ISO 1856 有这条）。刚下线就测，泡孔里的气体和残余应力还没稳，压缩变形往往测偏小——"料看着更好"经常只是测得早。
二、软层为什么"越用越不顶用"：泡孔塌陷不可恢复
先说结论：吸能靠的是泡孔塌陷，而塌陷不可逆。这个件的分水岭不在"多软"，在"塌得多快"。
据公开资料（B 级），发泡材料的压缩曲线分三段：头 5%-10% 是弹性的，像压一根弹簧；再往下泡壁屈曲、可控地垮塌，这一段叫"平台区"，才是真正吸能的那一段；泡孔几乎塌完，材料才突然变硬。吸能靠的是平台区，平台区长不长，决定这个软层能挨多少次。
同样是挨一下，护具和握把踩的不是同一条路径：
▸ 护具的大冲击模式：单次能量高，泡孔在一次变形里就被压到很深的位置。失效形态是整层泡孔一次性垮塌或局部压溃——外观只是"压扁了一块"，实际这一块的吸能能力已经没了。
▸ 握把的小能量多次模式：单次压缩很浅，但一天几千次，还长期被汗液和皮脂泡着。失效形态是泡孔渐进疲劳：先回弹变慢，再厚度留不住，最后表面发亮发硬、止滑衰减。外观还行，握感已经变了。
护具是"一次挨得狠"，握把是"天天挨得轻"。前者怕泡孔整层垮，后者怕泡孔慢慢疲。 同一种料，两条路上先坏的地方不一样。
顺带说清一个容易混的机理。都是发泡，聚丙烯泡壁是半结晶的，受压屈曲之后还能回弹；聚苯乙烯泡壁是无定形的，头一次大冲击就脆裂塌陷、不可恢复（B 级，公开技术资料）——所以 PP 基软层本来就定位在"能挨多次"。但诚实话是："能挨多次"不等于"无限次"。 公开资料里，发泡聚丙烯在密度 30 kg/m³ 一档，单次可吸 8-15 kJ/m³，能承受数十到数百次冲击；50% 压缩后回弹可到 95% 以上，而预载之后要 14 天左右性能才逐步恢复（B 级）。"要等 14 天"很关键——回弹是慢慢回来的，连轴转地用，性能来不及恢复。
还有一个绕不开的兑换：回弹速度。 回弹太快，能量没被吃掉就被顶回来，手上是"震手"、身上是"顶得慌"；回弹太慢，压下去回不来，就是"塌"。减震与回弹是一组对拉，不是能同时拉满的两个指标。
三、材料路线怎么分：PP + SEBS 共混发泡、PP + TPE、以及几条邻路边界
先说结论：这个件上不争"谁更好"，只看软层挂在哪块硬料上、要挨多大、要泡多久。
| 路线 | 拿到什么 | 代价 | 常见落位 |
|---|
| PP + SEBS 共混发泡 | 密度低、回弹好、可反复压缩、能回收 | 长期压缩后回弹会掉；充油体系怕溶剂 | 握把软层、轻防护具 |
| PP + TPE（SEBS 基）发泡 | 免底涂、湿态止滑好、-40℃ 不发硬 | 与 PP 硬芯只有弱作用，长期压缩与界面都偏弱 | 二次注塑软层、贴身件 |
| PP + TPE（SEBS + PP 基）发泡 | PP 组分与硬芯共结晶，界面与回弹一起改善；泡孔壁多一相增强 | 配方窗口窄，PP 加多了变硬、回弹变差 | 既要粘得住、又要耐反复压的件 |
| 硅胶 | 亲肤、耐温耐候、耐汗液与油脂突出 | 与 PP 不化学粘接，需底涂；成本高 | 高端贴身软层 |
| EPDM 硫化 | 耐候耐温好、耐汗液好 | 靠硫化成型、周期长 | 大面积护具软垫 |
| PU 泡棉 | 吸能密度高、软硬跨度大 | 怕水解，长期汗液下易粉化 | 高吸能护具内衬 |
| 凝胶 | 贴合好、压力分散好 | 重、回弹弱，不能当结构吸能层 | 局部减压垫 |
有一组概念必须说清："PP + TPE"不是一个材料，是一类材料；"SEBS 基"和"SEBS + PP 基"差在会不会和硬芯共结晶。 纯 SEBS 基回弹好、低温好，但与硬芯只有弱作用；预加一定比例的 PP 树脂，熔融时与硬芯共结晶，界面和抗反复压缩一起改善。软层粘不粘得住、挨多少次还回得来，从这里分岔。（界面剥离本篇不展开，同系列 PP-A25 已写透。）
这个件上改性PP 的身份，往往是"硬芯 + 发泡软层的载体"而不是软层本身：硬芯用抗冲共聚 PP，软层用 PP + SEBS 或 PP + TPE 发泡体系，配平比单独比较某一种软料有意义。
四、★ 选型判据表：七项指标，每项都带验证方法与标准号
先说结论：这张表最该看的不是门限值，是第三列——"拿什么测、怎么泡、测到多少算过"。
| 指标 | 门限值（典型） | 验证方法 / 标准 | 常见失效 | 通行解法 |
|---|
| 单次冲击传递力（护具） | EN 1621-1:2012：Level 1 平均 ≤35 kN、单次 ≤50 kN（B/C 区）；Level 2 平均 ≤20 kN、单次 ≤30 kN | EN 1621-1:2012：落锤 5 kg、能量 50 J、平冲头 40×80 mm、砧半径 50 mm；每件在三个区域各冲击一次 | 冲击区压溃、局部顶穿 | 厚度留量 + 硬壳分担峰值 |
| 多次冲击后的吸能保持 | 同一试样三次冲击都要过门限；湿态与高低温处理后同样要过 | EN 1621-1:2012（含湿态冲击；可选 -10℃×24 h、40℃×24 h） | 首次过关、之后泄漏能量 | 提高压缩永久变形表现 |
| 压缩永久变形与落球回弹 | 按件企标，常参照 50% 压缩、70℃×22 h；回弹与设计手感匹配 | GB/T 6669-2008 / ISO 1856（方法 A 70℃×22 h，或方法 B 23℃×72 h；试样 50×50×25 mm）；GB/T 6670-2008 / ISO 8307（钢球 φ16 mm、16.8 g、落高 500 mm；试样 100×100×50 mm） | 软层变薄、贴不住、回弹衰减、"塌"或"震手" | 回弹体系 + 厚度留量 + 充油量与 PP 组分配平 |
| 汗液浸泡后的止滑保持 | 干态 μ ≥0.8（宽松 ≥0.5）；湿态衰减 ≤15%，湿态仍 >0.5 | ASTM D1894 / GB/T 10006（须注明对摩面）；先按人工汗液浸泡再复测 | 汗手打滑、脱手 | 湿态防滑体系 + 表面纹路 |
| 人工汗液后的外观与沾色 | 变色与沾色一般不低于 3 级，贴身件常要求 3-4 级以上 | GB/T 3922-2013（修改采用 ISO 105-E04:2013）：酸性 pH 5.5±0.2、碱性 pH 8.0±0.2，37±2℃×4 h、12.5 kPa | 发粘、鼓包、变色、在浅色衣物上留印 | 低迁移油系 + 耐汗液配方 |
| 耐低温 | -20℃ 放置后不发硬脆、回弹不明显变慢 | 参照 EN 1621-1 的 T- 条件（-10℃×24 h）；或企标低温放置后复测硬度与冲击 | 冬天护具变硬、握把冰手易滑 | 走 SEBS 基体系（中嵌段 Tg 约 -60℃） |
| 气味与抗菌 | 气味 ≤3 级（VDA 270 口径）；抗菌按标准做，不做功效宣称 | VDA 270（B 级，德系口径）；ISO 22196:2011 / GB/T 31402-2015；防霉 ISO 16869 / ASTM G21 | 闷味、发臭、发霉 | 低气味体系 + 抗菌剂并验证耐久 |
文字版结论：七项里，"多次冲击后的吸能保持"和"汗液浸泡后的止滑保持"是两道一票否决的门槛，其余是配套项。另外，压缩永久变形和落球回弹都规定了试样状态调节（GB/T 6669 要求生产后放置并调节；GB/T 6670 要求 23±2℃ 调节至少 16 小时，开孔材料还要预压两次）——不按调湿条件测，同一批料能测出两个相反结论。
五、常见失效与根因：四个现象，先查设计还是先查料
先说结论：这个件的早期失效，多数不在"料软不软"，而在"设计给软层留了多大空间"。
失效一：头几次挺好，几次之后护具就顶不住了。 根因通常是三条之一：软层厚度留量不足，泡孔一次就被压到平台区末端；泡孔密度与硬度配得不匹配，局部先压溃；只有一层软层、没有硬壳分担峰值。先查结构有没有给软层留空间，再查料。
失效二：出手汗就打滑。 这类投诉最容易被归到"表面不够粗"。但汗液本身就是天然润滑剂，湿态摩擦系数下降往往比干态严重得多——干态好、湿态一塌糊涂的配方是存在的。判据必须干湿两态分开测，湿态衰减压到 15% 以内才算稳。
失效三：软层发粘、鼓包、变色。 运动场景的介质比工具手柄严苛：除了汗液，还有皮脂、防晒霜和驱蚊液，后两者含酒精与有机溶剂。据公开资料（B 级），SEBS 体系本身吸油、对脂肪烃耐受，但对芳香烃与极性溶剂并不耐受。这些介质下去，先动的是充油体系，表现出来就是发粘、鼓包、界面松。
失效四：深色软层在浅色运动服上留下印痕。 这是穿戴件上极常见、却很少被写进验收表的客诉。判据其实很成熟——人工汗液后的沾色级数：沾色低于 3 级通常判不合格，贴身件常要求 3-4 级以上（GB/T 3922-2013 口径）。选色和选配方时就要把这条摆上桌。
敢否定一个常见做法：护具吸能不够，就往软层里加厚、往配方里加软。这是错的，而且错得很隐蔽。加厚改善的只是"单次压得浅"，同时把回弹变慢、重量和闷热一起带上去；一味加软又把回弹提得太快，能量被顶回去，戴着更"顶"。改性PP 做这个件，该动的是"泡孔结构 + 回弹速度 + 硬壳分担"，不是厚度和硬度这两个旋钮。
六、验证顺序：吸能保持为什么必须排在最前
先说结论：这个件的钱花在顺序上。顺序错了，成本会在最后一步集中爆出来。
`
① 定场景与功能 护具（大冲击少次数）/ 握把（小能量多次数）先分开
↓ 分不清属于哪一类，后面的测试都没法设计
② 多次冲击 / 多次压缩的吸能保持 按 EN 1621-1 三次冲击；或按 GB/T 6669 压缩永久变形
↓ 吸能保持不达标 → 退回，先改软层厚度留量与泡孔配比
③ 人工汗液浸泡后复测 止滑（湿态 μ 衰减）+ 界面 + 外观（沾色）
↓ 发粘 / 鼓包 / 沾色低于 3 级 → 退回换低迁移油系
④ 低温性能 -10℃ 或 -20℃ 放置 24 h 后复测硬度与冲击
↓ 变硬脆、回弹显著变慢 → 退回换 SEBS 基体系
⑤ 耐 UV 与耐迁移 户外件不粉化、不褪色；浅色件复测沾色
↓
⑥ 实际运动场景验证 护具实戴冲击、握把连续握持出汗实测
`
为什么②必须排在③之前？②是"能不能用"的门槛，③是"能不能久用"的门槛。 吸能保持不过，泡着再好的汗液配方也是白做——护具一次没护住，就没有后面了。而③必须排在④之前，因为汗液是最可能一票否决的一项：常温干态测着挺好、泡完汗液就发粘的配方并不少见。
七、反向诚实：这几种情况同时出现，这个件就不该用 PP 基软层
先说结论：越是"又要吸能又要稳"的件，越不该拿一种软层硬撑。
| 出现的情况 | 为什么 PP 基软层不合适 | 该往哪走 |
|---|
| 要求专业级高等级冲击防护，且余量要留足 | 单层软层靠泡孔塌陷吃能量；要过更严的门限，厚度与密度都得上去，重量和闷热跟着来 | 走"硬壳 + 高吸能内衬"，内衬换高吸能密度体系 |
| 要求长期汗液浸泡且不允许止滑衰减 | 止滑依赖表面纹路与配方，长期泡汗后纹路被填、充油体系被迁移 | 走耐汗液耐油脂的极性体系，软层做成可更换件 |
| 要求极低密度同时又要高吸能 | 密度低就是泡孔多、泡壁少；吸能密度与低密度本身对拉 | 允许提高密度，或改多层结构（低密度外层 + 高吸能内芯） |
| 耐温要求长期在 80℃ 以上 | SEBS 基软层与 PP 硬芯都接近耐温边界，充油体系迁移加速 | 换极性硬芯配耐温配方，或走硅胶 / EPDM 体系 |
规律是一致的：只要出现"两个方向相反的要求同时要"，就说明这个件不该用改性PP 基软层硬撑。 遇到这种情况，我们的做法是先把这条讲清楚，再谈有没有折中空间——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：软层件的换料清单
先说结论：软层件换料动的不是一个件，是"硬芯 + 软层 + 界面 + 结构"四块。
| 要动的项 | 需要确认什么 | 不做会怎样 |
|---|
| 模具收缩率 | 硬芯与软层的收缩差异，决定转角与边缘内应力 | 转角剥离、翘边 |
| 软层厚度设计 | 剩余厚度够不够撑住整个服役期的压缩损失 | 用几个月就贴不住 |
| 浇口、排气与料温模温 | 发泡窗口窄于普通注塑，排气与浇口位置更敏感 | 欠注、泡孔不均、密度差、吸能离散 |
| 干燥与脱模 | 充油体系对水分与挥发分敏感；发泡件脱模早易鼓、晚易裂 | 银丝、气泡、变形、掉渣 |
| 色差与色迁移 | 深色软层要先做沾色验证再上机 | 在浅色衣物上留印，批次间争议 |
| 验证顺序 | 定场景 → 吸能保持 → 汗液复测 → 低温 → 耐 UV 与迁移 → 场景验证 | 风险全部压到最后一步集中爆发 |
九、一页纸汇报对照表：一次会上把软层方向定下来
| 场景 | 推荐路线 | 关键指标 | 验证标准 | 需先确认的条件 |
|---|
| 护膝、护肘（单次大冲击为主） | 抗冲共聚 PP 硬芯 + PP/SEBS 发泡软层，配硬壳分担峰值 | 单次传递力达标 + 三次冲击保持 | EN 1621-1:2012（含湿态与低温） | 目标等级、软层厚度留量 |
| 球拍、球杆握把（小能量多次数） | 抗冲共聚 PP 硬芯 + SEBS 基 TPE 发泡软层 | 压缩永久变形、回弹衰减、湿态 μ 衰减 ≤15% | GB/T 6669 / GB/T 6670 / ASTM D1894 | 是否长期贴肤、出汗量、清洁方式 |
| 骑行把套（户外 + 汗液 + 日晒） | PP + SEBS 共混发泡，加耐候与耐 UV 体系 | 老化后不粉化、止滑不衰减 | 氙灯老化 + 汗液浸泡后复测 | 户外年限、是否长期日晒 |
| 健身器械握柄（高频 + 高汗量） | 抗冲共聚 PP + PP/SEBS 发泡，表面做湿态纹路 | 湿态止滑保持、长期压缩后厚度 | ASTM D1894 + GB/T 6669 | 场馆清洁剂种类、使用频次 |
文字版结论：这张表的作用是让技术员把结论直接往上报。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，往往不是软不软
公开的问题。 这类件最常见的早期失效是"冲击后吸能衰减"与"汗液后止滑衰减"，由软料本身引起的比例并不高：前者多半落在厚度留量不足、泡孔密度与硬度不匹配、缺硬壳分担峰值三处；后者从表面纹路被填、充油体系迁移开始。
公开的判据。 冲击按 EN 1621-1:2012（5 kg 落锤、50 J，三区各冲击一次，Level 1 平均 ≤35 kN / Level 2 ≤20 kN，含湿态与高低温）；长期压缩按 GB/T 6669 / ISO 1856；落球回弹按 GB/T 6670 / ISO 8307；汗液后外观与沾色按 GB/T 3922-2013；摩擦系数干湿两态分开测。
通行的解法。 硬芯优先选抗冲共聚 PP；软层按件分工选 PP + SEBS 共混发泡或 PP + TPE 发泡；护具做"硬壳 + 软层"分工结构，握把把表面纹路与湿态防滑一起设计；配方用低迁移油系。
我们常供什么。 宁波市科隆新材料有限公司在这个件上常供的是改性聚丙烯（PP）粒子里的抗冲共聚方向，按软层体系与收缩要求给到对应的基材档位与填充方案，主要解决上面说的"吸能保持不住、软硬两层收缩对不上"这两件事；配方按工况调，可配合做小样比对与试模。
常见问答
问：护具是不是做得越软越安全？
答：不是。软度只决定压下去的手感，吸能靠的是泡孔塌陷留下的平台区。太软会把回弹拖慢，压下去回不来是"塌"；太弹则把能量顶回去，戴着"顶"。
问：运动握把和工具手柄，验收表能共用吗？
答：不能。工具手柄的重点是界面与握持手感（见同系列 PP-A25）；运动握把多两件事——汗液工况和反复握持后的止滑与厚度保持。
问：用人工汗液测，和实际戴出汗一样吗？
答：不一样，但它是可复现的那一个。人工汗液按 GB/T 3922-2013（修改采用 ISO 105-E04:2013）分酸、碱两种（pH 5.5 与 8.0），37℃×4 h——这项测的是"颜色与沾色"，止滑和界面要另做介质浸泡后复测。
| 工况 | 关键判据 | 自产常规供应 |
|---|
| 护具软层 | 单次传递力 + 多次冲击保持 | 抗冲共聚 PP 基材方向 + 收缩档配平 |
| 握把软层 | 压缩永久变形、湿态 μ 衰减 ≤15% | 按软层体系给到对应的基材与填充档 |
| 户外握把与把套 | 老化后不粉化、止滑不衰减 | 抗冲共聚 + 耐候耐 UV 方向 |
提醒一句：这个件出问题，最常见的错法是先换料。吸能衰减、止滑衰减、发粘、留印——每条的原因都不止一个。先定位，再换料。
十一、最后说三句
第一句，运动件的软层是吸能层，判据是"受过多少次冲击还能吸多少"，不是"软不软"。
第二句，护具和握把是两条失效路径。 护具怕一次挨得狠、泡孔整层垮；握把怕天天挨得轻、泡孔慢慢疲。
第三句，汗液是运动软层独有的那道门槛。 人工汗液浸泡后复测止滑、界面与外观，再做低温与耐 UV；只测干态和首次冲击，等于把风险留到客户身上。
关于我们
报价之前先聊三件事：这个件用在哪儿、要求哪几条、哪一条可以掉下来。
尤其第三件。改性 PP 的指标之间不是加法，是对拉——阻燃和增韧对拉，高流动和抗冲对拉，玻纤和尺寸稳定对拉。不排个先后，价格报不准，方案也稳不住。
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。
Sports equipment handles and protective gear use modified PP foamed with SEBS/TPE. The criterion is not 'how soft it is,' but 'how much impact it can endure and how much it can absorb.' This article breaks down the big impacts on protective gear and the small energy on handles into two failure paths, explains the mechanism of pore collapse, the re-testing for slip resistance after soaking in artificial sweat, the seven criteria and verification sequence, and specifies in which cases this part should not use a PP-based soft layer.
- General Outline: → 'Which Products Can Modified PP Be Used In? Material Map of 88 Items in 10 Major Fields' (PP-A0)
I've been using the handle for two months, and it still feels good, but as soon as my hands get sweaty, it slips, and the more I play, the more I hesitate to put in force.
The knee pads were pretty useful the first time I fell, but after falling two more times, my knees were still bruised — same gear, same spot.
The two people who said these sentences, one makes racket accessories, the other does protective gear contract manufacturing. Putting them in one article is because they point to the same thing:
The soft layer on the moving part is an 'energy-absorbing layer', not a 'comfort layer'. Its criterion is 'how much impact it can absorb after being subjected to how many impacts', not 'how soft it is'.
Hardness only determines the feel when you press down. What determines whether this part can still be used is whether the bubbles are still there and whether it can continue to collapse and absorb energy. Using modified PP as the carrier for this soft layer, the step most likely to go wrong is right here.
1. Six-dimensional breakdown of working conditions: The protective gear experiences few high-impact events, while the handle experiences many low-energy events.
Conclusion first: The first question to ask about these two types of parts is not 'how many degrees soft,' but 'how many times should this soft layer be pressed, and how much force each time?'
▸ Protective gear (knee pads, elbow pads, wrist guards) — high energy per impact, few times: impact tests are designed at the 50 J level, and a season only involves dozens to over a hundred impacts; the criteria are whether the peak energy of a single impact can be leveled off, and how much energy absorption remains after all impacts.
▸ Handles (rackets, cues, bike handle grips) — extremely small energy per use, but very high frequency: each grip involves a force of several hundred newtons, but it is done thousands of times a day and hundreds of hours a year; the criterion is how much thickness, resilience, and anti-slip property remain after long-term cycling.
Looking at the six dimensions together:
| Dimension | Actual operating conditions | Requirements for the materials |
|---|
| Temperature | Outdoor in summer 40-60℃; outdoor in winter -20~-10℃; sweat itself about 37℃ | Does not become hard and brittle at low temperatures, does not soften at high temperatures, energy absorption is re-tested in both states |
| Load | Protective gear single major impact (50 J level); handle repeated gripping pressure (hundreds of newtons per time, thousands of times per day) | For protective gear, look at peak value flattening and maintenance under repeated impacts; for grips, look at the thickness and rebound after long-term compression. |
| Medium | Sweat (salt, lactic acid, urea), sebum, sunscreen and mosquito repellent (containing alcohol and organic solvents), residual chlorine | Does not become sticky, does not blister, does not peel, does not change color, maintains friction when wet |
| Lifespan | Protective gear is based on seasons (dozens to over a hundred impacts); grips are based on hours of use (hundreds of hours per year) | Energy absorption retention after impact; rebound retention after long-term compression |
| Appearance | Dark soft layers leave marks on light-colored clothing; outdoor items turn yellow and chalky after UV exposure | Staining grade, color difference after aging |
| Compliance | Long-term skin contact, protective gear export following EN 1621 system, objective statements on antibacterial properties, odor | Colorfastness and migration, odor caliber, and antibacterial should be done according to standards |
Among the six dimensions, only two are of veto nature: energy absorption retention after impact, and anti-slip retention after sweating. Problems in the other dimensions at most affect the experience or require rework; these two, one concerns whether the protective gear can still protect, and the other concerns whether the grip will slip out of the hand.
An insider detail: For foam soft layer samples, compression set tests generally cannot be carried out within 72 hours after production. Before testing, the samples also need to be conditioned for more than 16 hours (GB/T 6669-2008 / ISO 1856 have this guideline). If measured immediately after production, the gas in the pores and residual stresses are not yet stabilized, so the compression deformation is often measured as smaller — the 'material looks better' is often just because it was measured too early.
2. Why soft layers become 'less effective the more you use them': Pore collapse is irreversible
Conclusion first: energy absorption relies on the collapse of pores, and this collapse is irreversible. The turning point for this part is not 'how soft it is,' but 'how quickly it collapses'.
According to publicly available information (Class B), the compression curve of foam materials is divided into three segments: the first 5%-10% is elastic, like compressing a spring; as compression continues, the cell walls buckle and collapse in a controlled manner. This segment is called the 'plateau region,' which is the truly energy-absorbing part; only when the pores are almost completely collapsed does the material suddenly become hard. Energy absorption relies on the plateau region, and the length of this plateau region determines how many times this soft layer can endure.
Even though they both take a hit, the protective gear and the grip follow different paths:
▸ High-impact mode of protective gear: the energy per hit is high, and the foam cells are compressed deeply in a single deformation. The failure mode is that the entire layer of foam cells collapses at once or is locally crushed—visually it just looks like 'a flattened section,' but in reality, this section has already lost its energy-absorbing capacity.
▸ Small energy repeated-use mode of the handle: Each compression is very shallow, but it happens several thousand times a day, and it is soaked in sweat and sebum for a long time. The failure pattern is gradual fatigue of the pores: first the rebound slows down, then the thickness cannot be maintained, and finally the surface becomes shiny and hard, with reduced slip resistance. The appearance is still fine, but the feel of the grip has already changed.
Protective gear experiences 'one heavy hit,' while the handle experiences 'light hits every day.' The former is afraid of the pores collapsing all at once, while the latter is afraid of the pores slowly fatiguing. Even with the same material, the part that fails first differs on the two paths.
Let me clarify a mechanism that is easy to confuse. Both are foams: the polypropylene foam walls are semi-crystalline, so they can rebound after being compressed and buckled; the polystyrene foam walls are amorphous, so a single major impact will cause them to fracture and collapse irreversibly (Class B, public technical data) — which is why the PP-based soft layer is originally intended to 'withstand multiple hits.' But to be honest: 'withstand multiple hits' does not mean 'unlimited times.' According to public data, foamed polypropylene with a density of 30 kg/m³ can absorb 8-15 kJ/m³ in a single impact and can endure dozens to hundreds of impacts; after 50% compression, the rebound can exceed 95%, but after preloading, it takes about 14 days for performance to gradually recover (Class B). The 'wait 14 days' is crucial — the rebound comes slowly, and if used continuously, the performance cannot recover in time.
There is another unavoidable exchange: rebound speed. If the rebound is too fast, the energy is pushed back before it is absorbed, causing 'shaky hands' for your hands and 'feeling off-balance' for your body; if the rebound is too slow, it won't return after being pressed down, which is called 'sagging'. Damping and rebound are a pair of opposing forces; they are not two parameters that can both be maximized at the same time.
3. How to classify material routes: PP-SEBS blend foaming, PP-TPE, and several adjacent boundary routes
Let's start with the conclusion: This matter is not about arguing 'which is better'; it only depends on which hard material the soft layer is on, how much pressure it will endure, and how long it will soak.
| Route | Get what | Cost | Common placements |
|---|
| PP SEBS blend foaming | Low density, good resilience, can be repeatedly compressed, recyclable | After long-term compression, rebound will decrease; oil-filled systems are sensitive to solvents. | Soft grip layer, light protective gear |
| PP TPE (SEBS-based) Foaming | No primer required, good wet slip resistance, does not harden at -40°C | It only has a weak effect with PP hard core, and both long-term compression and the interface are weak. | Secondary injection molded soft layer, close-fitting parts |
| PP TPE (SEBS PP-based) foaming | PP components co-crystallize with the hard core, improving both the interface and resilience; the cell walls are reinforced by an additional phase. | The formulation window is narrow; adding more PP makes it harder and reduces resilience. | Parts that need to adhere well and withstand repeated pressing |
| Silicone | Skin-friendly, resistant to temperature and weather, outstanding resistance to sweat and oils | Does not chemically bond with PP, requires primer; high cost | High-end close-fitting soft layer |
| EPDM vulcanization | Good weather resistance and temperature resistance, good sweat resistance | Relying on vulcanization molding, long cycle | Large-area protective padding |
| PU foam | High energy absorption density, wide range of softness and hardness | Prone to hydrolysis, easily powdery under long-term exposure to sweat | High energy-absorbing protective gear lining |
| Gel | Fits well, distributes pressure well | Heavy and weak in rebound, cannot serve as a structural energy-absorbing layer | Local pressure relief pad |
There is a set of concepts that must be clarified: 'PP TPE' is not a single material, it is a type of material; the difference between 'SEBS-based' and 'SEBS PP-based' is whether it can co-crystallize with a hard core. Pure SEBS-based has good rebound and low-temperature performance, but only weak interaction with the hard core; if a certain proportion of PP resin is added beforehand, it will co-crystallize with the hard core during melting, improving both the interface and resistance to repeated compression. Whether the soft layer can stick, and how many times it can recover, branches out from here. (Interface delamination will not be detailed in this article; it has been thoroughly explained in the same series PP-A25.)
The role of modified PP in this part is often as a 'carrier for a soft foamed layer with a hard core' rather than the soft layer itself: the hard core uses impact copolymer PP, the soft layer uses a PP-SEBS or PP-TPE foaming system, and balancing the proportions is meaningful only when compared to a single type of soft material.
4. ★ Selection Criteria Table: Seven indicators, each with verification methods and standard numbers
Let's start with the conclusion: the part of this table that you should pay the most attention to is not the threshold values, but the third column — 'what to test with, how to prepare it, and how much counts as passing'.
| Indicator | Threshold Value (Typical) | Verification Method / Standard | Common failures | Common solution |
|---|
| Single Impact Transmission Force (Protective Gear) | EN 1621-1:2012: Level 1 Average ≤35 kN, Single impact ≤50 kN (B/C area); Level 2 Average ≤20 kN, Single impact ≤30 kN | EN 1621-1:2012: Drop weight 5 kg, energy 50 J, flat striker 40×80 mm, anvil radius 50 mm; each piece is impacted three times in three areas | Crushed in the impact zone, local punching failure | Thickness allowance Peak load shared by hard shell |
| Energy absorption retention after multiple impacts | The same sample must pass the threshold in all three impacts; it must also pass after wet, high, and low temperature treatments. | EN 1621-1:2012 (including wet impact; optional -10℃ × 24 h, 40℃ × 24 h) | Pass for the first time, then leak energy | Improve compressive permanent deformation performance |
| Compression set and ball rebound | According to piece-specific standards, often refer to 50% compression, 70°C × 22 h; rebound matches the designed feel. | GB/T 6669-2008 / ISO 1856 (Method A 70°C × 22 h, or Method B 23°C × 72 h; specimen 50 × 50 × 25 mm); GB/T 6670-2008 / ISO 8307 (steel ball φ16 mm, 16.8 g, drop height 500 mm; specimen 100 × 100 × 50 mm) | Soft layer thinning, not sticking, rebound attenuation, 'collapse' or 'hand-shock' | Rebound system Thickness allowance Oil fill and PP component balance |
| Slip resistance maintained after sweat soaking | Dry state μ ≥ 0.8 (loose ≥ 0.5); wet state decay ≤ 15%, still > 0.5 when wet | ASTM D1894 / GB/T 10006 (must specify the friction surface); first soak in artificial sweat and then retest | Sweaty hands slipping, losing grip | Wet anti-slip system Surface texture |
| Appearance and staining after artificial sweat | Color change and staining are generally not lower than grade 3, and close-fitting garments often require grade 3-4 or above. | GB/T 3922-2013 (Modified adopting ISO 105-E04:2013): acidic pH 5.5±0.2, alkaline pH 8.0±0.2, 37±2℃ × 4 h, 12.5 kPa | Sticky, blistered, discolored, leaves marks on light-colored clothing | Low-migration oil-based, sweat-resistant formula |
| Low temperature resistant | After being stored at -20℃, it does not become hard and brittle, and the rebound slows down noticeably. | Refer to the T-condition of EN 1621-1 (-10℃ × 24 h); or retest hardness and impact after storing at low temperature according to the company standard | Winter protective gear becomes hard, and the handle gets icy, making it easy to slip | Use SEBS-based system (middle block Tg about -60°C) |
| Odor and Antibacterial | Odor ≤ grade 3 (VDA 270 standard); antibacterial according to standard, no efficacy claims made | VDA 270 (Class B, German standard); ISO 22196:2011 / GB/T 31402-2015; Mold resistant ISO 16869 / ASTM G21 | Stuffy smell, foul odor, moldy | Low-odor system, antibacterial agent, and durability verification |
Text Version Conclusion: Among the seven items, 'energy absorption retention after multiple impacts' and 'anti-slip retention after sweat soaking' are two veto thresholds, while the rest are supporting items. In addition, both compressive permanent deformation and ball rebound specify sample condition adjustments (GB/T 6669 requires placement and adjustment after production; GB/T 6670 requires adjustment at 23±2℃ for at least 16 hours, and perforated materials need to be pre-compressed twice)—if the moisture conditioning requirements are not followed, two opposite conclusions can be obtained from the same batch of material.
5. Common Failures and Root Causes: Four Phenomena, Should You Check Design First or Material First?
Let's start with the conclusion: The early failure of this component is mostly not about 'whether the material is soft,' but about 'how much space the design leaves for the soft layer.'
Failure 1: It works well for the first few times, but after a few uses, the protective gear can no longer hold up. The root cause usually falls into one of three categories: insufficient thickness allowance in the soft layer, causing the foam cells to be compressed down to the edge of the platform in one go; mismatch between foam cell density and hardness, leading to local collapse first; only one layer of soft material without a hard shell to share the peak load. First, check whether the structure allows space for the soft layer, then check the material.
Failure 2: Slipping due to sweaty hands. These complaints are most easily categorized as 'surface not rough enough.' However, sweat itself is a natural lubricant, and the friction coefficient in a wet state often decreases much more than in a dry state—formulations that are fine when dry but terrible when wet do exist. The criteria must measure dry and wet states separately, and the decline in the wet state must be kept within 15% to be considered stable.
Failure Mode 3: Soft layer becomes sticky, bulges, and discolors. The media in sports scenarios are harsher than tool handles: in addition to sweat, there are sebum, sunscreen, and insect repellent, the latter two containing alcohol and organic solvents. According to public information (Class B), the SEBS system itself absorbs oil and is resistant to aliphatic hydrocarbons, but is not resistant to aromatic hydrocarbons and polar solvents. Under the influence of these media, the first to be affected is the oil-filled system, which manifests as stickiness, bulging, and interface loosening.
Failure Four: Dark soft layers leave marks on light-colored sportswear. This is a very common customer complaint for wearable items, yet it is rarely included in inspection sheets. The criteria are actually well established—staining levels after exposure to artificial sweat: a staining level below grade 3 is usually considered non-compliant, and close-fitting garments often require grade 3-4 or above (according to GB/T 3922-2013 standards). This factor should be considered when choosing colors and formulations.
Dare to challenge a common practice: if protective gear doesn't absorb enough energy, people just make the soft layer thicker or soften the formula. This is wrong, and the mistake is very subtle. Increasing thickness only improves 'how shallow a single compression is,' while also slowing rebound and adding weight and heat; simply making it softer makes the rebound too fast, sending the energy back, making it feel more 'bouncy' when worn. For modified PP making this part, the parameters to adjust are 'pore structure, rebound speed, and hard-shell support,' not the thickness and hardness knobs.
6. Verification sequence: Why energy absorption maintenance must come first
Conclusion first: The money for this piece is spent on the sequence. If the sequence is wrong, the costs will explode at the final step.
`
① Define the scenario and function: Protective gear (high impact, low frequency) / Grip (low energy, high frequency) separate them first
↓ Can't tell which category it belongs to, so the following tests can't be designed
② Energy absorption retention under multiple impacts / multiple compressions According to EN 1621-1 for three impacts; or according to GB/T 6669 for compression permanent deformation
↓ Energy absorption does not meet the standard → Return, first adjust the remaining thickness of the soft layer and the pore ratio
③ Retest after artificial sweat soaking Anti-slip (wet-state μ attenuation) Interface Appearance (staining)
↓ Sticky / Blistering / Color transfer below level 3 → Return and replace with low migration oil-based type
④ Low-temperature performance Retest hardness and impact after being placed at -10℃ or -20℃ for 24 hours
↓ Becomes hard and brittle, rebound significantly slows → revert to replacing SEBS-based system
⑤ UV resistance and migration resistance: Outdoor parts do not chalk or fade; light-colored parts are retested for staining.
↓
⑥ Actual sports scene verification: Real-wear impact testing of protective gear and continuous grip sweating measurement
`
Why must ② come before ③? ② is the threshold of 'whether it can be used,' and ③ is the threshold of 'whether it can be used for a long time.' If the absorption cannot be maintained, even the best sweat formula is useless——if the protective gear fails even once, there is no next step. And ③ must come before ④ because sweat is the item most likely to cause an outright failure: it's not uncommon for a formula to measure well in normal dry conditions but become sticky after soaking in sweat.
7. Reverse Honesty: If these situations occur simultaneously, this piece should not use a PP-based soft layer
Conclusion first: The more a part is 'expected to absorb energy and remain stable,' the less it should rely on a single soft layer for support.
| The situation that occurred | Why is the PP-based soft layer not suitable | Which way should I go? |
|---|
| Requires professional-grade high-level impact protection, with sufficient margin left. | Single-layer soft layers absorb energy through pore collapse; to get past stricter thresholds, both thickness and density need to increase, bringing weight and stuffiness along with them. | Go with a hard shell and high energy-absorbing liner, replace the liner with a high energy-absorbing density system |
| Requires long-term immersion in sweat and does not allow anti-slip degradation | Anti-slip depends on surface texture and formulation; after long-term exposure to sweat, the texture gets filled, and the oil system migrates. | Use a polar system resistant to sweat and oil, with the soft layer made as a replaceable part |
| Requires extremely low density while also needing high energy absorption | Low density means more pores and fewer cell walls; the energy absorption density is related to the low density itself. | It is permissible to increase the density, or change to a multi-layer structure (low-density outer layer, high energy-absorbing core). |
| Temperature resistance requirement: long-term above 80℃ | Both the SEBS soft layer and the PP hard core are close to the temperature resistance limit, and the migration in the oil-filled system accelerates. | Change to a polar hard core with a heat-resistant formula, or go with a silicone / EPDM system |
The pattern is consistent: Whenever there is a 'requirement for two opposite directions at the same time,' it indicates that this part should not use modified PP with a soft layer and hard support. In such cases, our approach is to first make this point clear, and then discuss whether there is any room for compromise—the subsequent orders that are hard to handle will ultimately have to be reworked and returned for compensation.
8. What needs to be moved for material replacement: Material replacement list for soft layer components
First, to state the conclusion: when replacing the soft layer component, it's not just one part that moves; it's the four pieces: 'hard core, soft layer, interface, and structure.'
| Items to move | What needs to be confirmed | What will happen if I don't do it? |
|---|
| Mold shrinkage rate | The shrinkage difference between the hard core and the soft layer determines the internal stress at corners and edges | Corner peeling, edge lifting |
| Soft layer thickness design | Is the remaining thickness enough to withstand the compression loss over the entire service life? | It won't stick after a few months |
| Gate, venting, and material temperature mold temperature | The foam injection window is narrower than ordinary injection molding, and the venting and gate positions are more sensitive. | Lack of filler, uneven porosity, density differences, scattered energy absorption |
| Drying and Demolding | The oil-filled system is sensitive to moisture and volatile components; foam parts tend to bulge if demolded too early and crack if demolded too late. | Silver threads, bubbles, deformation, flaking |
| Color Difference and Color Migration | Dark soft layers need to undergo color adhesion verification before being loaded onto the machine. | Leaving marks on light-colored clothes, disputes between batches |
| Verification order | Set scene → Energy absorption retention → Sweat re-test → Low temperature → UV resistance and migration → Scene verification | All the risks are concentrated to explode at the final step |
9. One-page report comparison table: Decide the direction of the soft layer in one meeting
| Scene | Recommended Route | Key indicators | Verification Standard | Conditions that need to be confirmed first |
|---|
| Knee pads and elbow pads (mainly for single high-impact events) | Impact-copolymer PP hard core PP/SEBS foamed soft layer, paired with hard shell to share the peak load | Single delivery force meets the standard Maintains after three impacts | EN 1621-1:2012 (including wet and low temperature conditions) | Target grade, remaining thickness of soft layer |
| Racket and cue grips (low energy, high frequency) | Impact-resistant copolymer PP hard core SEBS-based TPE foamed soft layer | Compression set, rebound decay, wet state μ decay ≤15% | GB/T 6669 / GB/T 6670 / ASTM D1894 | Whether it is in contact with the skin for a long time, amount of sweating, cleaning method |
| Bicycle handlebar grips (outdoor, sweat, sun exposure) | PP SEBS blended foam, with weather resistance and UV-resistant system | Does not chalk after aging, slip resistance does not diminish | Xenon lamp aging Retested after sweat immersion | Outdoor exposure years, whether long-term sun exposure |
| Fitness equipment handle (high frequency, high sweat) | Impact-resistant copolymer PP PP/SEBS foamed, surface textured in wet state | Slip resistance in wet conditions, thickness after long-term compression | ASTM D1894 GB/T 6669 | Types of venue cleaners and frequency of use |
Text Version Conclusion: The purpose of this table is to allow technicians to report conclusions directly. There is only one criterion for judgment — whether the customer can use this table to determine the direction of the materials in a single meeting.
10. The part that tends to go wrong the most is often not whether it's soft or not.
Public issues. The most common early failures of such components are 'energy absorption decay after impact' and 'anti-slip decay after sweat,' and the proportion caused by the soft material itself is not high: the former mostly occurs in three areas—insufficient thickness allowance, mismatch between pore density and hardness, and lack of a hard shell to share the peak; the latter starts from surface patterns being filled in and the migration of the oil-filled system.
Public criteria. Impact tested according to EN 1621-1:2012 (5 kg drop hammer, 50 J, each of the three zones impacted once, Level 1 average ≤35 kN / Level 2 ≤20 kN, including wet state and high/low temperatures); long-term compression tested according to GB/T 6669 / ISO 1856; ball rebound tested according to GB/T 6670 / ISO 8307; appearance and staining after sweat tested according to GB/T 3922-2013; coefficient of friction measured separately for dry and wet conditions.
Common solution. For the hard core, prioritize impact-resistant copolymer PP; for the soft layer, select PP-SEBS blend foam or PP-TPE foam based on component division; the protective gear is designed with a 'hard shell-soft layer' structural division, and the handle's surface texture is designed together with wet anti-slip; use low-migration oil-based formulations.
What we usually supply. Ningbo Kolon New Materials Co., Ltd. usually supplies modified polypropylene (PP) pellets with impact-resistant copolymer orientation in this case, providing corresponding base material grades and filling schemes according to the soft layer system and shrinkage requirements, mainly to address the two issues mentioned above: 'energy absorption cannot be maintained' and 'the shrinkage of the soft and hard layers does not match.' The formula can be adjusted according to working conditions and can be used for small sample comparison and mold trials.
Frequently Asked Questions
Question: Are protective gears safer the softer they are?
Answer: No. Softness only determines the feel when pressed down, while energy absorption depends on the platform area left after the foam cells collapse. If it's too soft, rebound is slowed, and pressing down without coming back is a 'collapse'; if it's too springy, the energy is pushed back, resulting in a 'push' when worn.
Question: Can the acceptance form for sports grips and tool handles be used interchangeably?
Answer: No. The focus of a tool handle is on the interface and grip feel (see the same series PP-A25); a sports grip involves two additional aspects—sweat conditions and maintaining slip resistance and thickness after repeated gripping.
Question: If tested with artificial sweat, is it the same as actually wearing it and sweating?
Answer: Not the same, but it is the one that is reproducible. Artificial sweat is divided into acidic and alkaline types (pH 5.5 and 8.0) according to GB/T 3922-2013 (modified adopting ISO 105-E04:2013), 37°C × 4 hours—this test measures 'color and staining'; slip resistance and interface need to be retested after immersion in the medium.
| Operating condition | Key criterion | Self-produced regular supply |
|---|
| Protective gear soft layer | Single delivery force Multiple impacts maintained | Impact-resistant copolymer PP substrate orientation Shrinkage adjustment balance |
| Soft grip layer | Compression permanent deformation, wet μ decay ≤15% | Provide the corresponding substrate and filler grade according to the soft layer system |
| Outdoor grip and handle cover | Does not chalk after aging, slip resistance does not diminish | Impact copolymer Weather-resistant and UV-resistant orientation |
One reminder: when this part has a problem, the most common mistake is to replace the material first. Energy absorption attenuation, anti-slip attenuation, stickiness, leaving marks — each issue has more than one cause. Diagnose first, then replace the material.
Eleven, finally say three sentences
The first sentence: The soft layer of the moving part is the energy-absorbing layer, and the criterion is 'how much impact it can absorb after being hit multiple times,' not 'whether it is soft or not.'
The second sentence: Protective gear and grips are two failure modes. Protective gear is vulnerable to a single severe impact, causing the entire foam layer to collapse; grips are vulnerable to daily light impacts, causing the foam to gradually fatigue.
The third sentence: sweat is the unique threshold of the sports soft layer. After soaking in artificial sweat, re-test anti-slip, interface, and appearance, then do low temperature and UV resistance tests; only testing in the dry state and on the first impact is equivalent to leaving the risk to the customer.
About Us
Let's talk about three things before quoting: where this part will be used, which requirements it must meet, and which ones can be dropped.
Especially the third point. The indicators for modified PP are not additive; they are trade-offs—flame retardancy versus toughness, high flow versus impact resistance, glass fiber versus dimensional stability. Without ranking them, you can't quote a price accurately, nor can you settle on a solid plan.
Ningbo Cologne New Materials Co., Ltd. produces modified polypropylene (PP) granules, covering homopolymer, random copolymer, and block copolymer base materials, as well as modifications including filled, glass fiber reinforced, toughened, flame-retardant, low odor and low VOC, weather-resistant, and scratch-resistant without coating; it also deals in PP resins from major petrochemical plants, off-spec materials, and bulk materials.
