Flexible Reinforced Hose and Method of Making the Same

It is known as from U.S. Pat. Nos. 2,977,839 and 3,251,381 to plasticize the surface of nylon tubing by using a resorcinol-water solution, to apply to the plasticized surface a nylon fiber reinforcement, and to cure the tubing-reinforcement assembly by passing it through a water bath to remove the plasticizing agent. The cured assembly is then heated and the reinforcement is plasticized followed by extrusion of a nylon sheath over the platicized reinforcement. Similar flexible reinforced hoses are disclosed in U.S. Pat. Nos. 3,654,967, 3,682,201 and 3,790,419.

It is also known from U.S. Pat. No. 3,861,973 to make a flexible reinforced nylon hose by contacting nylon tubing with an aqueous resorcinol solution or an alcoholic resorcinol solution, drying the solution to form crystalline material on the surface of the tubing, and applying to the tubing a layer of a synthetic or natural fiber followed by heating the reinforced tubing to a temperature of at least about 150.degree. F.

In contradistinction to the foregoing patents, the flexible reinforced hose herein comprises nylon tubing to which a reinforcement of a synthetic or natural fiber is bonded by applying the fiber to the meta-cresol plasticized outer surface of the tubing, the excess meta-cresol having previously been wiped off the tubing, so that only the residual meta-cresol remains in the tubing-reinforcement assembly.

The FIGURE of the drawing shows the present flexible reinforced hose and its method of manufacture.

The flexible reinforced hose H herein comprises a nylon core tube 1 to which a reinforcement 2 (braided or spirally wrapped) of a synthetic or natural fiber is mechanically or fusion bonded by applying the reinforcement 2 to the meta-cresol plasticized surface of the core tube 1. If the core tube-reinforcement assembly is to have a plastic sheath 3 thereover, the assembly will be passed through an extruder cross head 4 for extruding sheathing material over the core tube-reinforcement assembly.

In the manufacture of the flexible reinforced hose H, the nylon core tube 1 from a supply reel 5 passes through a heated meta-cresol bath 6, the nylon core tube 1 entering the bath 6 through a rubber or rubber-like seal 7 and leaving the bath 6 through a rubber or rubber like seal and wiper 8 which wipes off excess meta-cresol from the core tube 1 so that there is a minimal residual meta-cresol content in the plasticized surface of the core tube 1. The nylon core tube 1 may be of type 6/6, type 6, type 11, or type 6/6-6 copolymer or any other nylon having the desired physical properties that are desired in the flexible hose H.

The meta-cresol bath 6 comprises at least 50% meta-cresol with the balance being composed of cresol, para-cresol, or other phenols. The preferred meta-cresol bath 6 comprises 95% meta-cresol with the balance being cresol or some other phenols. Satisfactory results have been obtained with technical grade of meta-cresol comprising 54% meta-cresol, 29% para-cresol and the balance other phenols.

The temperature of the meta-cresol bath 6 should be maintained between about 90.degree. to 170.degree. F, the solvation of the nylon core tube 1 being hastened by the application of heat and, of course, the heating of the bath 6 decreases the viscosity of the meta-cresol bath 6 to thereby provide a bath with greater wetting power. The heating of the meta-cresol bath 6 and consequent decreased viscosity facilitates wiping of all excess meta-cresol from the core tube 1. The removal of all excess meta-cresol from the core tube eliminates the possibility of hose reinforcement 2 damage by solvation of the reinforcement 2. The sealing of the meta-cresol bath 6 by seals 7 and 8 as aforesaid and the removal of the excess meta-cresol by seal and wiper 8 minimizes hazards associated with inhalation of toxic fumes. It has been found that an exposure of the nylon core tube 1 to the meta-cresol bath 6 for about one minute followed by wiping off all excess meta-cresol by the seal and wiper 8 provides a very thin plasticized layer on the core tube 1. While the surface of the core tube 1 is still plasticized, the core tube 1 passes through apparatus 9 which applies the reinforcement 2 in the form of a braid or spiral wrapping thus to bond the reinforcement 2 to the core tube 1. The reinforcement 2 may be a nylon, polyester, aramid, rayon, cotton or other synthetic or natural fiber. When nylon fiber is the reinforcement 2, type 6/6 nylon is preferred. When the reinforcement 2 is of nylon, the innermost surface of the reinforcement 2 will be fusion bonded to the nylon core tube whereas in the case of other reinforcements 2 the bond will be a mechanical bond between the plasticized outer surfce of the core tube 1 and the inner surface of the reinforcement 2. In any case, there will not be solvation of the reinforcement 2 sufficient to cause weakening thereof.

When the nylon core tube 1 is of type 11, the temperature of the meta-cresol bath 6 should be maintained between 120.degree. F and 170.degree. F.

When the tube-reinforcement assembly is to have a sheath 3 thereover it is preferred that it be of nylon but any other plastic material may be employed such as polyurethane and in that case a polyurethane adhesive may be applied on the reinforcement 2 to provide an adhesive bond when the assembly is passed through the extruder cross-head 4.