Composition for use between polymeric tie plates and cross ties

#This invention relates to a gap-filling, adhesive composition for use with polymeric tie plates which are disposed in the dapped area of a wood, concrete or polyethylene railroad cross tie.

#In the art of fastening railroad rails to cross ties, a metal tie plate is generally used between the rail and the cross tie. In U.S. Pat. No. 2,886,248 (Laudig) it was taught that a tie pad composition could be used between the metal tie plate and the wooden cross tie. The autoadhesive, autosealing tie pad composition contained: 45-65 wt. % asphalt, 5-25 wt. % heavy naphthalene base residuum, 3-12 wt. % pine tar and 10-35 wt. % of at least one rubbery elastomer. The asphalt has a penetration between 30 and 50 and a softening point between 100.degree. and 170.degree. F. (37.78.degree. C.-76.67.degree. C.). The naphthalene base has a viscosity of about 40-55 Saybolt Fural seconds at 210.degree. F. (98.89.degree. C.). The pine tar is a high grade retort tar made by the destructive distillation of wood. The rubbery elastomer can be a natural rubber, used rubber, or a synthetic rubber like a copolymer of butadiene and styrene (GR-S). The tie pad also may contain a fibrous membrane or filler but it may consist simply of the adhesive and sealant composition.

#In U.S. Pat. No. 3,358,925 of which I was a co-inventor, there was disclosed a non-metallic tie plate which could be adhesively bonded to a wooden cross tie. The non-metallic plate consists of a plastic material like polyurethane or epoxy. The adhesive used to bond these non-metallic tie plates to the wood cross tie are resorcinol or epoxy adhesives. Also in my prior U.S. Pat. No. 3,544,006, I disclosed a non-metallic tie plate comprised of high density polyethylene. The high density polyethylene tie plate is disposed in a dapped area of a railroad cross tie and is usable with railroad spikes.

#FIG. 1 is a view of the gap-filling, adhesive composition being applied to a polyethylene tie plate.

#FIG. 2 is a view of the gap-filling, adhesive composition adhering to a polyethylene tie plate before being placed in the dapped area of a cross tie.

#FIG. 3 is an exploded perspective view of the disposition of the gap-filling, adhesive composition between a polyethylene tie plate with a rail and spike and the dapped area of a cross tie.

#In FIG. 1 a high density polyethylene tie plate, for example, is shown generally indicated at 1 and having applied to it the gap-filling, adhesive composition of this invention. The gap-filling, adhesive composition 2 is applied to the high density polyethylene tie plate 1 and the release paper 3 is pulled from the gap-filling, adhesive composition as the composition comes in contact with the high density polyethylene tie plate.

#The high density polyethylene tie plate or, in general, the polymeric tie plate consists of a right-angled parallelepiped which has a relatively flat bottomed surface for resting upon a railroad cross tie and has an upper surface spaced apart from the bottom surface. The recessed upper surface carries a rail; the recess extends from one end to the opposite end of the tie plate and defines a planar surface which is canted from one side to the opposite side of the tie plate at a slope of approximately one unit of rise to 40 units of run with respect to the bottom surface. Shoulders are thereby provided at each side of the plate which shoulders provide an inner surface meeting the planar recess surface for restricting the lateral movement of the rail carried by the recess. Also provided by the shoulders is an outer surface meeting the flat bottom surface which, when the tie plate is disposed into a recess rabbetted on a tie, a dapped area, restricts the lateral movement of the tie plate with respect to the tie by the outer surface engaging the sidewalls of the recess in the tie to maintain gage. Slots in each shoulder are spaced at locations on each side of the tie plate, the slots on each side being diametrically opposed and each slot extending from the edge of the plate to the recessed surface of the tie plate for receiving a spike. This high density polyethylene tie plate is further defined and described in my U.S. Pat. No. 3,544,006, the teaching of which is hereby incorporated by reference.

#The gap-filling, adhesive composition according to this invention can be used to attach preferably the high density polyethylene tie plate to the cross tie in a dapped area, but tie plates made of other polymeric substances like polyolefin, polypropylene, higher molecular weight polyethylene such as ultra high molecular weight polyethylene, and polyurethane can be attached with this gap-filling, adhesive composition. The composition consists of 65 to 75 wt. % of an asphalt, 10 to 20 wt. % of a styrene butadiene copolymer and 7 to 25 wt. % of a processing oil.