What are the bonding methods of PTFE

- Jul 13, 2019-

Bonding method of polytetrafluoroethylene Any solid to be bonded must be wettable by the adhesive and have adhesion. The surface energy of PTFE material is low, the contact angle of the surface to the liquid is large, the wettability is poor, and the adhesion ability is small, so the adhesion to other substances is poor, and it is generally adhered after special treatment. Chengdu Senfa Rubber & Plastic Co., Ltd. specializes in the surface treatment of PTFE and provides sodium naphthalene treatment solution with good formulation effect. The following three commonly used bonding methods for polytetrafluoroethylene (PTFE) are introduced: 1.1 Naphthalene solution treatment bonding method Naphthalene solution treatment of fluorine-containing materials, mainly through the chemical reaction between the etching solution and PTFE plastic, tearing off the material Part of the fluorine atoms on the surface, thus leaving a carbonized layer and some polar groups on the surface. Infrared spectroscopy indicates that polar groups such as hydroxyl groups, carbonyl groups and unsaturated bonds are introduced on the surface, and these groups can increase the surface energy, reduce the contact angle, and improve the wettability, from difficult to sticky. This is a better method and a more common method in all the methods currently studied. Sodium naphthalene tetrahydrofuran is generally used as the etching solution. The treatment bonding steps are as follows: (1) Treatment liquid preparation: a certain amount of sodium metal is added to a solution of tetrahydrofuran and naphthalene, wherein the mass fraction of metal sodium is controlled at 3% to 5%, and stirred at room temperature for about 2 hours until The color of the solution is dark brown or black; (2) The PTFE workpiece to be treated is immersed in the solution for about 5~10 min, and then taken out and immersed in acetone solution for 3~5 min;

(3) Take out the workpiece from the acetone solution, rinse it with water and then dry it in the dark place; (4) Select epoxy resin, silicone or polyurethane as the adhesive, apply it evenly on the treated surface to be bonded and Bonding immediately, after standing at 24~30 °C for 24h, it can be bonded firmly. Sodium liquid ammonia solution treatment bonding method The treatment bonding mechanism of this method is similar to the sodium naphthalene solution treatment bonding method, and need not be repeated here. The processing and bonding steps are as follows: (1) Preparation of treatment liquid: a certain amount of sodium metal is added to the liquid ammonia solution at room temperature to prepare a sodium ammonia solution having a mass fraction of 1% to 5%, and after the reaction is complete, Can be used; (2) immerse the PTFE workpiece to be treated into the sodium ammonia solution for about 5~10s, take it out and soak it in methanol or ethanol solution for 5~10min; (3) take out the workpiece from methanol or ethanol solution, rinse with water Clean and dry in the dark place; (4) Select epoxy resin, silicone or polyurethane as the adhesive, apply evenly on the treated surface to be bonded and bond immediately, and let stand at 24~30 °C for 24h. It can be bonded firmly afterwards. Naphthalene solution treatment bonding method and sodium liquid ammonia solution bonding method are not only suitable for self-bonding of PTFE materials, but also suitable for mutual bonding between PTFE and stainless steel or other materials. Pay attention to the following points during use: the amount of the treatment liquid should be appropriate, and the amount of the treatment should be related to the size of the workpiece; the used treatment liquid can be reused, and must not be discarded to prevent contamination of the environment; the treatment liquid can not contact the skin. When storing, pay attention to oxygen and water, especially sodium naphthalene solution. 1.3 Bonding method without special treatment on the surface For the bonding of PTFE workpieces that are not particularly important, the FS-203A silicone pressure-sensitive adhesive produced by Shanghai Organic Fluorine Research Institute is used for bonding. FS-203A glue is water-based, one-component solvent glue, good water resistance, high temperature resistance, low temperature, strong adhesion. For PTFE and PTFE bonding, the shear strength can be as high as 6~12kg/cm2. It is bonded to various non-surface-treated fluoroplastics and bonded to other materials. The bonding process is as follows: (1) The surface of the PTFE and the adherend is first wiped clean with acetone or ethanol solution, and dried naturally; (2) FS-203A is evenly applied on both bonding surfaces for 2 times, each time. Dry for 10~15min, it is better to not stick the rubber surface; (3) After the glue is dried, bake in the oven at 100~150°C for 15min, remove the heat-bonded assembly, and cure at room temperature for 24h; (4) After high and low temperature tests (550 ° C, 4 h, -40 ° C, 4 h) and moisture test (humidity 90%, 48 h), the joints were not peeled off and loosened.www.yihaoptfe.com