EVA添加POE有哪些優缺點？

What Are the Advantages and Disadvantages of Adding POE to EVA?

PART 2

再加入SEBS改善物性，為何雙螺桿分散才是關鍵？

When SEBS Is Added to Improve Properties, Why Is Twin-Screw Dispersion the Key?

雙螺桿的四個核心優勢

Four Core Advantages of a Twin-Screw Extruder

1. 高界面更新率：兩支螺桿互相嚙合，反覆分流、合流與拉伸熔體。

High interfacial renewal rate: The two intermeshing screws repeatedly divide, recombine, and stretch the melt.

2. 可分區設計剪切：輸送元件負責前進，捏合塊提供可控分散，避免全程高剪切。

Zoned shear design: Conveying elements move the material forward, while kneading blocks provide controlled dispersion without imposing high shear throughout the entire machine.

3. 精準供料與側餵：可將高黏SEBS、油品、相容劑或填料在適當位置加入。

Precise feeding and side feeding: High-viscosity SEBS, oils, compatibilizers, or fillers can be introduced at appropriate locations.

4. 真空排氣與穩定造粒：移除水分與揮發物，生成均勻母粒供後續低溫加入發泡系統。

Vacuum venting and stable pelletization: Moisture and volatiles are removed to produce a uniform masterbatch for later low-temperature addition to the foaming system.

 

五、雙螺桿不是剪切越高越好：要控制比能量與熔體溫度

V. More Shear Is Not Always Better in Twin-Screw Processing: Control Specific Energy and Melt Temperature

雙螺桿的價值不是「把轉速開到最高」，而是用可重複的比機械能（SME）、停留時間與熔體溫度建立形態。SME可作為每公斤物料實際承受機械能的工程指標；過低無法打散SEBS，過高則可能造成EVA熱史增加、分子鏈斷裂、色變或後續發泡窗口縮小。

The value of a twin-screw extruder is not to run at the highest possible speed, but to establish morphology through reproducible specific mechanical energy (SME), residence time, and melt temperature. SME is an engineering measure of the mechanical energy actually applied per kilogram of material. If it is too low, SEBS cannot be dispersed; if it is too high, EVA may accumulate excessive thermal history, undergo chain scission or discoloration, and lose part of its downstream foaming window.

製程變數 Process Variable	過低時 When Too Low	過高時 When Too High	建議監控 Recommended Monitoring
螺桿轉速 Screw Speed	分散不足、產量低 Insufficient dispersion and low throughput	剪切發熱、降解、停留變短 Shear heating, degradation, and shorter residence time	轉速、扭矩、SME、熔體溫度 Speed, torque, SME, and melt temperature
捏合塊角度／數量 Kneading-Block Angle/Number	SEBS團聚殘留 Residual SEBS agglomerates	壓力與溫升過大 Excessive pressure and temperature rise	機頭壓力、粒子切片、濾網壓差 Die pressure, pellet cross-sections, and screen pressure differential
喂料量 Feed Rate	停留過長、易熱劣化 Overlong residence time and susceptibility to thermal degradation	填充過高、混煉不足 Excessive fill and insufficient mixing	扭矩百分比、產量、比能量 Torque percentage, throughput, and specific energy
溫度設定 Temperature Setpoints	塑化不完全 Incomplete plasticization	EVA／助劑熱史過大 Excessive thermal history for EVA/additives	各區實測熔體溫度，不只看設定 Actual melt temperature in each zone, not just the setpoint
真空排氣 Vacuum Venting	水分與揮發物殘留 Residual moisture and volatiles	過強可能抽走低分子助劑 Excessive vacuum may strip low-molecular-weight additives.	真空度、揮發分、粒子氣泡 Vacuum level, volatile content, and bubbles in pellets
安全的兩段法｜第一段只製作EVA／POE／SEBS聚合物母粒，必要時加入相容劑；第二段再以低溫密煉或適合設備加入DCP、發泡劑與活化系統。避免活性過氧化物與發泡劑在高剪切雙螺桿中承受不必要熱史。 Safe two-stage method | In the first stage, make only an EVA/POE/SEBS polymer masterbatch, adding a compatibilizer if needed. In the second stage, add DCP, the blowing agent, and the activation system in a low-temperature internal mixer or other suitable equipment. This avoids exposing active peroxide and blowing agents to unnecessary thermal history in a high-shear twin-screw extruder.

六、相容劑何時需要？SEBS並不一定自動停留在界面

VI. When Is a Compatibilizer Needed? SEBS Does Not Necessarily Migrate to and Remain at the Interface

SEBS的EB中段與POE相容性通常較佳，但EVA的VA極性提高後，界面張力仍可能上升。若顯微形態顯示大顆粒、撕裂沿界面失效或貼合性明顯下降，可評估EVA-g-MAH、SEBS-g-MAH、EAA等相容策略。相容劑的功能是降低界面張力、抑制聚併或形成界面反應；添加過量則可能提高黏度、吸濕、影響交聯或改變發泡。

The EB midblock of SEBS is generally more compatible with POE, but interfacial tension may still rise as the VA-derived polarity of EVA increases. If microscopy shows large domains, tearing fails along interfaces, or lamination performance declines markedly, compatibilization strategies such as EVA-g-MAH, SEBS-g-MAH, or EAA can be evaluated. A compatibilizer lowers interfacial tension, suppresses coalescence, or creates interfacial reactions; excessive addition, however, may raise viscosity, absorb moisture, affect crosslinking, or alter foaming.

七、分散品質如何直接影響發泡？

VII. How Does Dispersion Quality Directly Affect Foaming?

圖3｜粗大SEBS團聚體會形成應力集中與泡孔不均；細小分散相才可能穩定泡孔壁。

Figure 3 | Coarse SEBS agglomerates create stress concentrations and nonuniform cells; only a finely dispersed phase can potentially stabilize cell walls.

1. 成核不均：粗粒、污染物或界面空隙會造成局部過度成核與粗孔並存。

Nonuniform nucleation: Coarse particles, contaminants, or interfacial voids cause excessive local nucleation alongside coarse cells.

2. 泡孔壁薄弱：大相域橫跨泡孔壁時，界面可能成為破孔與撕裂起點。

Weak cell walls: When a large domain spans a cell wall, its interface may become the starting point for cell rupture and tearing.

3. 交聯不均：DCP與聚合物接觸歷史不同，使局部凝膠率與熔體強度波動。

Nonuniform crosslinking: Differences in the contact history between DCP and the polymers cause local fluctuations in gel content and melt strength.

4. 局部熱點：高黏團聚體提高剪切發熱，造成色差、焦燒或發泡劑提前反應。

Local hot spots: High-viscosity agglomerates increase shear heating, causing color variation, scorch, or premature blowing-agent reaction.

5. 表面與尺寸失控：粗孔、破孔及相界面回縮會放大表面粗糙與後收縮。

Loss of surface and dimensional control: Coarse cells, ruptured cells, and interfacial shrink-back magnify surface roughness and post-shrinkage.

建議的分散驗證方法

Recommended Methods for Verifying Dispersion

層級 Level	方法 Method	可判讀資訊 Information Obtained
快速製程 Rapid Process Checks	扭矩、SME、熔體溫度、濾網壓差 Torque, SME, melt temperature, and screen pressure differential	批次能量、熱史與團聚趨勢 Batch energy, thermal history, and agglomeration trends
粒子／片材 Pellets/Sheets	光學顯微鏡、染色切片、表面掃描 Optical microscopy, stained cross-sections, and surface scanning	黑點、未熔粒與相尺寸分布 Black specks, unmelted particles, and domain-size distribution
高階形態 Advanced Morphology	SEM／AFM；選擇性蝕刻 SEM/AFM; selective etching	分散相尺寸、界面與連續相轉換 Dispersed-phase size, interfaces, and continuous-phase transition
熱分析 Thermal Analysis	DSC、DMA	結晶變化、Tg、PS微區與阻尼窗口 Changes in crystallinity, Tg, PS microdomains, and the damping window
交聯流變 Crosslinking Rheology	MDR、動態流變、凝膠率、溶脹 MDR, dynamic rheology, gel content, and swelling	交聯—產氣窗口與網路完整性 Crosslinking-gas-generation window and network integrity
發泡結果 Foaming Results	密度、泡孔尺寸／分布、撕裂、回彈、壓縮永久變形 Density, cell size/distribution, tear strength, resilience, and compression set	形態是否真正轉化為成品效益 Whether morphology truly translates into finished-product benefits

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