Structured dense fluoropolymer film and method of making same
A polymer film, structured technology, used in chemical instruments and methods, flat products, flexible coverings, etc., to solve problems such as barrier layers that are not suitable for low surface tension fluids
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Embodiment 1
[0095] Example 1: Preparation of dense fluoropolymer films
[0096] PTFE resin and isoparaffin lubricant ( K, Exxon, Houston, TX) was mixed at a concentration of 0.184 g / g. The mixture is then blended and compressed into cylindrical pellets. The pellets were heat conditioned at a temperature of 49°C for about 24 hours. The pellets were then extruded through a rectangular die at a compression ratio of 182:1 to form tapes having a thickness of 0.635 mm. The strip is then dried to remove residual lubricant.
[0097] After drying, the tape was expanded in the machine direction (eg, machine direction) at a temperature of 330°C with a draw ratio of about 3.4:1. The tape was then expanded in the transverse direction at a temperature of 330°C with a draw ratio of about 9.4:1 to form an unsintered ePTFE membrane.
[0098] The film is then densified by compression between rollers or other suitable compression equipment at a temperature and pressure to substantially eliminate pores...
Embodiment 2
[0102] Example 2: Preparation of Structured Fluoropolymer Films
[0103] The dense fluoropolymer film of Example 1 was adhered to a stretched elastic substrate according to the structuring methods described herein. The chamber was heated to a temperature of 180°C. After about 5 minutes, the stretched elastic substrate is allowed to relax at a rate of about 5 mm / s, thereby returning it to a preset less stretched state. Measurements were made for various strain set points (% maximum elongation of the elastomeric substrate) for the x-axis (ie, machine direction) and y-axis (ie, transverse direction). Relaxing the stretched elastic substrate causes the adhered film to wrinkle to form a structured fluoropolymer film. Mass per unit area (MPA) and surface strain were calculated as previously described. The results are shown in Table 2.
[0104] Table 2
[0105]
Embodiment 3
[0106] Example 3: Preparation of dense fluoropolymer films
[0107] The PTFE resin mixture was prepared as described in Example 1 and formed into cylindrical pellets. The pellets were then extruded through a rectangular die at a compression ratio of 182:1 to form tapes having a thickness of 0.635 mm. The strip is then dried to remove residual lubricant.
[0108] After drying, the tape was expanded in the longitudinal direction between heated drums at a temperature of 330°C with a draw ratio of about 3.4:1. The tape was then expanded in the transverse direction at a temperature of 300°C with a draw ratio of 9.4:1 to form an unsintered ePTFE membrane.
[0109] Then, as described in Example 1, the film was densified. After compression, the membrane was loaded onto the pantograph. Then, the material was heated to about 370°C for about 10 minutes. The heated film was then stretched at a strain rate of about 10% per second until a ratio of about 1.8:1 in the machine direction a...
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Abstract
Description
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