Method for producing fixing-unit member and fixing-unit member

1. A method for producing a fixing-unit member including a base, a rubber elastic layer, and a tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA) layer containing 70 wt % or more of a PFA, the method comprising:

(I) a primer-layer-forming step of forming a primer layer by applying a primer to an outer circumferential surface of a rubber roller prepared by forming the rubber elastic layer on an outer circumferential surface of the base, the primer containing a fluorocarbon resin that has a melting point equal to or lower than a melting point of the PFA contained in the PFA layer;

(II) a rubber-roller-sheathing step of sheathing the rubber roller including the primer layer, with a thermally shrinkable tube formed by diametrically expanding a PFA tube so as to have an inner diameter more than an outer diameter of the rubber roller including the primer layer, the PFA tube containing 70 wt % or more of the PFA and having an inner diameter equal to or less than the outer diameter of the rubber roller including the primer layer;

(III) a PFA-layer-forming step of forming the PFA layer from the thermally shrinkable tube by heating the thermally shrinkable tube around the rubber roller to a temperature equal to or higher than a crystallization temperature of the PFA contained in the thermally shrinkable tube so that the thermally shrinkable tube is thermally shrunken and is fused with the rubber roller including the primer layer, with the primer layer between the thermally shrinkable tube and the outer circumferential surface of the rubber roller; and

(IV) a reheating step of heating the PFA layer to a temperature equal to or higher than the melting point of the PFA contained in the PFA layer,

further comprising, after the reheating step, a rapid-cooling step of cooling the PFA layer at a rate of 200° C./min or higher in a manner such that cold air at 1° C. to 25° C. is blown to the PFA layer for 15 to 90 seconds,

wherein, prior to the PFA-layer-forming step, a preheating step of preheating the rubber roller sheathed with the thermally shrinkable tube in a temperature range of 150° C. to 250° C. and for a time range of 5 to 100 minutes in an electric oven.

2. The method according to claim 1 , wherein, in the PFA-layer-forming step, the temperature to which the thermally shrinkable tube is heated is lower than the melting point of the PFA contained in the thermally shrinkable tube.

3. The method according to claim 1 , wherein the PFA layer has a thickness of 50 μm or less.

4. The method according to claim 1 , wherein the PFA tube is formed by extrusion in a temperature range of 380° C. to 440° C.

5. The method according to claim 1 , wherein the PFA-layer-forming step is performed while a metal shaft is inserted through the base.

6. The method according to claim 5 , wherein the reheating step is performed without the metal shaft inserted through the base.

7. The method according to claim 1 , wherein the base is composed of a metal or a heat-resistant resin.

8. The method according to claim 1 , wherein the rubber elastic layer is composed of a rubber composition containing a thermally conductive filler and at least one heat-resistant rubber selected from the group consisting of silicone rubber and fluorocarbon rubber.

9. The method according to claim 1 , wherein the fixing-unit member is a fixing roller or a fixing belt.

10. The method according to claim 1 , wherein the fixing-unit member is a pressing roller or a pressing belt.