中底踩一个月就塌，回弹跑没了。超临界发泡中底密度没控住，轻弹就是噱头。
中底踩一个月就塌，回弹跑了
超临界发泡中底是“轻弹的件”：回弹、轻量、耐疲劳。材料要回弹好、轻量、耐疲劳——结论先给：超临界发泡中底用 TPU 或 TPE 发泡是主流；
高端定位，PEBA 发泡优先。
超临界发泡中底最大的坑：鞋垫回弹差，脚后跟先抗议。回弹差，脚后跟先知道——回弹，是发泡中底的底线。
超临界发泡中底是功能件：回弹差、塌陷都是问题。材料选对，跑鞋才稳——功能件，别省料钱。
超临界发泡为什么偏向 TPE
超临界发泡中底用 TPE 的理由：回弹可做、轻量可做、耐疲劳、效率高——四条合起来，适合发泡中底。
回弹是核心：发泡中底轻且弹，回弹差走路久了脚后跟酸。回弹测试写进验收——回弹，是发泡中底的底线。
轻量不能省：轻是发泡的意义。密度数据写进验收——超重，就是问题。
跑步轻量疲劳，三道关
跑步工况：反复压缩。回弹数据要验——回弹差，就是问题。
轻量工况：重量敏感。密度数据要验——超重，就是问题。
疲劳工况：长期使用。疲劳数据要验——塌陷，就是问题。
TPE 发泡还是 EVA？一表看清
| 维度 | TPE 发泡 | EVA |
|---|
| 回弹 | 好 | 中 |
| 轻量 | 好 | 好 |
| 耐疲劳 | 好 | 中 |
| 成本 | 高 | 低 |
| 工艺 | 超临界 | 模压 |
| 用途 | 高端 | 常规 |
表格读法：EVA 便宜但回弹差；TPE 发泡回弹好——高端鞋 TPE 发泡，常规 EVA。
按定位选：高端发泡，常规 EVA。
发泡中底验收：回弹轻量两笔账
| 项目 | 方法 | 标准 |
|---|
| 回弹 | 回弹测试 | 按标准 |
| 密度 | 密度杯 | 按目标 |
| 疲劳 | 循环压缩 | 按次数 |
| 泡孔 | 断面观察 | 均匀 |
表格读法：回弹、密度、缓冲四项走完，发泡中底才合格。
回弹，是发泡中底的底线。
只图轻，三个坑塌出来
坑一：只图轻。密度压太低回弹垮掉，脚感马上塌——回弹必测。
坑二：泡孔漏测。泡孔不均——断面观察，必做。
坑三：疲劳漏测。塌陷——疲劳测试，必测。
选中底料先控发泡密度
三问：回弹率多少、密度多少、发泡倍率多少。一验：实际跑步实测——三问一验，供应商底细清楚。
回弹验证要先行：先测落球回弹率，再谈价格——回弹，是发泡中底的底线。
留样要成习惯：每批留样，回弹密度按批次复测。批次换料先对比再放量——批次稳，客诉少。
发泡中底密度做到 0.15-0.25 g/cm³，回弹率要过 60%。 泡孔断面看均匀，泡孔不均局部就塌陷——倍率窗口要锁。
EVA 模压便宜但回弹差，TPE/TPU 超临界发泡回弹好但贵。 高端跑鞋发泡 TPU，常规训练 EVA——按定位选工艺路线。
中底回弹差不是料软，是泡孔不均加倍率飘。 前掌缓震后掌回弹要分区密度，一块料打天下脚感必分层。
发泡中底验收四件套：回弹率、密度、循环压缩 10 万次、泡孔断面。 数据别只报一个回弹率，缓震曲线和能量回归率一起要。
密度 0.20 加回弹 65%、循环压缩过检，中底踩一年还 Q。 每批留样测密度加疲劳，泡孔断面逐批留档对比。
超临界发泡中底常见问题与对策表
| 现象 | 原因 | 对策 |
|---|
| 回弹差 | 发泡不足 | 调倍率 |
| 塌陷 | 耐疲劳弱 | 换耐疲劳料 |
| 泡孔不均 | 工艺不稳 | 调参数 |
| 超重 | 密度高 | 换轻量料 |
| 批次差 | 配方漂移 | 锁窗口 |
超临界发泡中底泡孔直径按 50-150μm 验收，泡孔不均局部就塌。 断面切片看泡孔均匀度，大小差一倍回弹就分层——倍率和温度窗口要一起锁。
中底能量回归率按 60% 以上验收，回弹率高不等于能量回归高。 回弹率是单次弹跳，
能量回归是多次循环衰减——跑鞋中底两个数据都要，别只看回弹。
发泡中底疲劳按 10 万次压缩后高度保持 90% 验收。 中底踩一年塌陷多少，疲劳数据说了算——新中底回弹好不代表十万次后还弹，衰减曲线要测。
超临界发泡温度窗口按 ±2℃ 控制，温度偏一点泡孔就不均。 发泡工艺窗口窄，温度压力时间三个参数联动——别只调一个参数，三个一起锁才稳。
科隆客户案例：交期紧现货对不上，留样数据补认证
沧州一家鞋材厂，超临界发泡中底交期紧，现货牌号性能对不上。科隆配合提供同批次留样与物性数据，通过第三方检测并补齐认证，按期交付。留样加数据，是急单的底气——数据齐，认证快，交期才保得住。
小结
超临界发泡中底的选型，回弹先看，轻量再比，鞋垫回弹差脚后跟先抗议，回弹是底线。
The midsole collapsed after just a month of stepping, and the rebound is gone when running. The density of the supercritical foamed midsole was not controlled, so the light bounce is just a gimmick.
The midsole collapsed after just a month of use, and the rebound is gone.
The supercritical foam midsole is a 'light and elastic component': resilient, lightweight, and fatigue-resistant. The material needs to be resilient, lightweight, and fatigue-resistant — here's the conclusion first: using TPU or TPE foaming for supercritical foam midsoles is mainstream;
High-end positioning, PEBA foam preferred.
The biggest drawback of supercritical foaming midsoles: poor insole rebound, with the heel protesting first. Poor rebound, the heel feels it first—rebound is the baseline for foamed midsoles.
The supercritical foamed midsole is a functional component: poor rebound and collapse are both problems. Choosing the right material keeps running shoes stable—functional components, don't skimp on material costs.
Why supercritical foaming tends to favor TPE
Reasons for using TPE in supercritical foam midsoles: can provide rebound, can be lightweight, fatigue-resistant, and highly efficient—these four together make it suitable for foam midsoles.
Rebound is key: The foam midsole is light and springy; if the rebound is poor, your heels will hurt after walking for a long time. Rebound testing is included in the acceptance—rebound is the bottom line for foam midsoles.
Lightweight should not be compromised: lightness is the meaning of foaming. Density data should be recorded for acceptance—overweight is a problem.
Light fatigue from running, three barriers
Running condition: repeated compression. Rebound data needs to be checked — if the rebound is off, that's the problem.
Lightweight operating condition: weight-sensitive. Density data must be checked — overweight is a problem.
Fatigue condition: long-term use. Fatigue data must be verified—collapse is the problem.
TPE or EVA foam? A chart to see clearly
| Dimension | TPE Foaming | EVA |
|---|
| rebound | Good | middle |
| lightweight | Good | Good |
| Fatigue-resistant | Good | middle |
| Cost | Tall | Low |
| Craft | supercritical | Molding |
| Purpose | High-end | Regular |
Table reading: EVA is cheap but has poor rebound; TPE foam has good rebound — high-end shoes use TPE foam, regular ones use EVA.
Select by positioning: high-end foam, standard EVA.
Foamed midsole inspection: two accounts of rebound and lightweight
| Project | Method | standard |
|---|
| rebound | Rebound Test | According to the standard |
| Density | Density cup | By target |
| Fatigue | Cyclic compression | By frequency |
| pore | Cross-sectional observation | Even |
Table reading: Only after completing the four items of rebound, density, and cushioning is the foam midsole considered qualified.
Rebound is the bottom line of the foam midsole.
Only aiming for lightness, three holes collapsed.
Pitfall 1: Only aiming for lightness. If the density is too low, the rebound collapses, and the foot feel immediately sinks — rebound must be tested.
Pitfall 2: Undetected blowholes. Uneven blowholes—cross-sectional observation is a must.
Pitfall 3: Fatigue omissions. Collapse—fatigue testing is a must.
Select the base material first and control the foaming density
Three questions: What is the rebound rate, what is the density, and what is the foaming ratio? One test: measured during actual running — three questions and one test, the supplier's details are clear.
Rebound verification must come first: measure the ball rebound rate first, then discuss the price — rebound is the bottom line for foam midsoles.
Making sample retention a habit: retain samples from each batch and re-test the rebound density by batch. When changing materials between batches, compare first before scaling up—the batch is stable, and customer complaints are few.
The density of the foamed midsole should be between 0.15-0.25 g/cm³, and the rebound rate must exceed 60%. The cross-section of the foam cells should appear uniform; if the cells are uneven, parts will collapse — so the process window for the ratio must be locked.
EVA molding is cheap but has poor rebound, while TPE/TPU supercritical foaming has good rebound but is expensive. High-end running shoes use foamed TPU, and regular training shoes use EVA — choose the process route according to positioning.
Poor midsole rebound is not due to soft material, but because of uneven foam cells combined with inconsistent scaling. The forefoot needs cushioning and the rearfoot needs rebound, requiring zoned density; a single piece of material cannot achieve the best feel across the foot.
Foamed midsole inspection four-piece set: rebound rate, density, 100,000 cycles of compression, and foam cell cross-section. Don't just report a single rebound rate; the cushioning curve and energy return rate should be included together.
Density 0.20, rebound added 65%, cyclic compression tested. The midsole still feels springy after a year of wear. Samples from each batch are kept to test density and fatigue, and the cross-sections of the foam cells are archived for comparison batch by batch.
Table of Common Problems and Countermeasures in Supercritical Foamed Midsoles
| Phenomenon | Reason | Countermeasure |
|---|
| Poor rebound | Insufficient foaming | Adjust Magnification |
| collapse | Weak fatigue resistance | Replace with fatigue-resistant material |
| Uneven pores | Unstable process | Adjust parameters |
| Overweight | High density | Switch to lightweight material |
| Batch difference | Formula Drift | Lock the window |
In supercritical foaming midsoles, the cell diameter is accepted at 50-150 μm; if the cells are uneven, some areas will collapse. Cross-sectional slices are used to check cell uniformity; if the size difference is twice, rebound will cause delamination—the magnification and temperature window need to be locked together.
The energy return rate of the midsole is accepted if it is above 60%. A high rebound rate does not equal high energy return. The rebound rate refers to a single bounce.
Energy return is multiple cycles of decay—the midsole data of running shoes should consider both values, not just the rebound.
Foamed midsoles pass inspection if they retain 90% of their height after 100,000 compressions. How much a midsole will collapse after a year of use is determined by fatigue data—the good rebound of a new midsole does not mean it will still rebound after 100,000 cycles, the decay curve needs to be measured.
The supercritical foaming temperature window is controlled within ±2°C; if the temperature deviates slightly, the pores become uneven. The foaming process window is narrow, with three interrelated parameters: temperature, pressure, and time—don’t adjust just one parameter; locking all three together ensures stability.
Cologne Customer Case: Tight delivery schedule with mismatched stock, sample data used to supplement certification
A shoe material factory in Cangzhou had tight deadlines for supercritical foamed midsoles, and the performance of the available grades did not match. Kolon cooperated by providing samples from the same batch along with physical property data, conducted third-party testing, and completed the certification to ensure on-time delivery. Samples plus data are the confidence for urgent orders—complete data allows for fast certification, and only then can the delivery deadline be guaranteed.
Summary
In selecting a supercritical foamed midsole, first look at rebound, then compare weight. If the insole has poor rebound, the heel complains first; rebound is the bottom line.
