Ni-P-PTFE複合層化學鍍製備與其抗沾黏特性之研究

Abstract

鎳磷合金(Ni-P alloy)有優異的硬度(> 600 Hv)、耐磨耗及化學耐蝕性，已為機械、模具、汽車、光電及電子製造等領域廣泛的應用。聚四氟乙烯(鐵氟龍) (poly-tetra-fluoro-ethylene, PTFE)亦具有優異之自潤滑性(摩擦係數極低)、表面抗粘黏性、超疏水自潔性、耐腐蝕性、絕緣性，在生化、醫療與食品相關器具已有廣泛應用。模造成型之模仁表面如沉積 PTFE之薄膜，可使模仁具有極佳之脫模與離型效果，避免壓印或射出成型之高分子材料沾黏於模仁表面，特別是當進行微/奈米等級結構之成型時，此沾黏現象特別容易發生。然而，此PTFE薄膜一般是以蒸鍍、旋鍍、噴塗、浸漬等方式塗佈於模仁表面，則於脫模離型過程中PTFE薄膜容易產生剝離脫落現象，致使模仁的耐用性不佳，故必須提出其他有效的解決方案。 因此，本研究在化學鍍(無電鍍)(electroless plating)鎳磷合金(Ni-P alloy)的程序中，加入0.2 μm之PTFE顆粒，以進行Ni-P/PTFE複合層之製備。此複合層在應用時，可兼具鎳磷合金優異之硬度與耐磨耗性，以及PTFE膜之低摩擦係數、超撥水性、高抗沾黏等特性。此外，由於PTFE顆粒均勻地鑲嵌於鎳磷合金鍍層內部與表面，顆粒具有不易脫落的特性，可明顯改善僅PTFE塗覆於模仁表面，所造成之模仁耐用性不佳的缺點。化學鍍實驗中分別控制鍍液pH值、操作溫度，PTFE顆粒添加量、界面活性劑FC-134濃度等參數，探討Ni-P/PTFE複合層之析鍍速率、複合層中PTFE之沉積量、微硬度的影響，以及與抗沾黏、自潔性、防污性功能相關之接觸角特性。 實驗結果顯示鍍浴的pH值必須控制在4.80-4.92範圍內，以維持鍍液的穩定性。溫度的提升，析鍍膜可獲得較佳之接觸角度，但隨著浴溫的增加，析鍍速率反而會減少，例如，在85 ℃操作條件下鍍層的接觸角為113.47o、鍍率為15.8 m/hr，95℃時接觸角為146.29o、鍍率為5.7 m/hr。析鍍時間與沉積厚度呈線性關係，時間愈長可得較厚之薄膜，但鍍液中PTFE含量超過7.5 cc/L，沉積速率受到限制反而減緩。杜邦公司(Du Pont)的PTFE懸浮液，其鍍層品質深受界面活性劑FC-134的影響，其最佳條件為95 ℃鍍液含300 mole/L FC-134、PTFE含量7.5㏄/L、化鍍20 min，可得接觸角度140.01°，鍍層厚度6.5 m、平均硬度173.54 Hv。使用日本World Metal Co, LTD 的PTFE懸浮液，其鍍液可以不使用FC-134，在95℃浴溫、PTFE含量7.5㏄/L、化鍍20 min的最佳條件下，可得接觸角度147.70°，鍍層厚度5.5 m、平均硬度160.80 Hv。目前的研究進度已獲得超疏水性之Ni-P-PTFE複合層，並應用析鍍於具有微結構之Ni-Co模仁表面，可得接觸角141.42°，且實際進行熱印壓模(Hot embossing)之測試，經過壓膜與脫膜實驗後，量測接觸角為137.89°。因此，本研究所製備之Ni-P-PTFE複合層有抗沾黏的能力，可助Ni-Co模仁之離型性效果。

Excellent hardness(＞600HV), abrasion and chemical corrosion resistance has a wide range of applications in areas such as machinery、molds、photo electronics and electronics manufacturing. Poly-tera-fluoro-ethylene also has its excellent self-lubricity、surface anti-sticky、super hydrophobic self-cleaning、corrosion resistance、insulation resistance, has been widely used in biochemical、medical、and food-related utensils. The mold caused by the type of mold surface, such as deposition of thin film of PTFE has excellent stripping and releasing effect, to avoid embossing or injection molding of the polymer material sticking in the mold surface, especially when micro / nano-level structure of the molding, this adhesion phenomenon is particularly easy to occur. However, this PTFE film coating on the surface of the mold generally based on the method of vapor deposition、spin coating 、spraying、dipping, etc, is easily generate the phenomenon of peeled off in the process of stripping from the mold which result in poor durability. So it must propose another effective solutions. Therefore, Therefore, in this research, the procedures for the chemical plating of Ni-P alloy, we add 0.2 μm PTFE particles in order to prepare the Ni-P-PTFE composite layer. This complex layer has both the superior hardness、wear resistance and low coefficient of friction、super water-repellent、high anti-sticking properties of the PTFE membrane. In addition, due to the PTFE particles uniformly embedded in a nickel-phosphorus alloy plating in internal part and outer surface, the particles have the characteristics of not easy to fall off, it can significantly improve the disadvantage of PTFE coated on the surface of the mold, caused by the poor durability of the mold. In electroless plating experiments, we control the parameters of pH value、the operating temperature、the amount of the PTFE particles are added、surfactant FC-134 concentration to investigate the plating rate of Ni-P-PTFE composite layer、the deposition amount of the PTFE composite layer、the impact of micro-hardness and contact angle characteristics associated with anti-adhesion、self-cleaning、anti-fouling features. The experimental results show that the pH value of the plating bath must be controlled within the 4.80-4.92 ranges, in order to maintain the stability. The plating film can has a good contact angle by elevating the bath temperature, but with the increase in the bath temperature, the plating rate instead will be reduced, for example, the contact angle of the coating film is 1l3.47° at 85 ℃ operating conditions, the plating rate is 15.8 μm /hr ; the contact angle of the coating film is 146.29° at 95 °C, the plating rate is 5.7 μm/hr. Plating time and deposition thickness shows the linear relationship, the longer time may have a thicker film, but the PTFE content in the bath of more than 7.5 cc/L, the deposition rate is limited and slow. The suspension of PTFE of Du Pont Company (Du Pont), its coating quality is deeply influence by the surfactant FC-134, and the optimum conditions is 95 ℃ bath containing 300 μmole / L FC-134、PTFE content 7.5 cc/L、plating 20 min, the contact angle 140.01° is get, coating thickness is 6.5 μm, the average hardness is 173.54 Hv. By using the PTFE suspension of World Metal Co., Japan, Ltd, the bath does not use the FC-134, under the optimum conditions of 95 ℃ bath、the PTFE content of 7.5 cc/L、plating 20 min, the contact angle can be 147.70°, thickness of the coating film is 5.5 μm、the average hardness of 160.80 HV. The current research get the super hydrophobic Ni-P-PTFE composite layer and is preparing the plating in the microstructure of Ni-Co mold surface, contact angle 141.42° is get and test of hot embossing after lamination and stripping experiments, contact angle 137.89° is get. Therefore, the institute of Ni-P-PTFE composite layer anti-adhesion ability can help the Ni-Co mold from the type of effect.