US 2801948 A
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1957' j D.'W. R. WALKER 2,801,948
METHOD OF BONDING ATTACHMENTS TO FLEXIBLE SHEET PLASTICS Filed Sept. "7, 1955 l nvenior M mmWw/wm A ttorn e 1 United States Patent METHOD OF BONDING ATTACHMENTS TO FLEXIBLE SHEET PLASTICS Derek William Ross Walker, Barnt Green, England Application September 7, 1955, Serial No. 532,914
5 Claims. (Cl. 154---116) This invention relates to an improved method of attaching eyelets, hooks, buttons, handles and the like to flexible sheet plastics.
Since flexible sheet plastics were first introduced, attempts have been made to use them as a substitute for, or rather an improvement over, textiles, for use as tarpaulins, tents, vehicle hoods, portable water tanks and so on, in fact where heavy fabrics such as canvas have been used hitherto. Plastics have also been tried in place of textiles in the manufacture of bags and other containers for powdered or granular material, bags for toilet articles, and even of garments. Plastics have a number of obvious advantages over textiles for such applications, in particular where exposed to the Weather. For example, they are rot-proof, and are unaffected by attack from insects, and furthermore, if a transparent plastic is used, stores contained under a tarpaulin, or in a covered vehicle, can be checked visually without the necessity for exposing them. Plastic sheet may also be chaper and lighter for a given area than a textile and is completely impervious to moisture. Also, it does not support combustion and may be more resistant to chemicals.
The greatest drawback that has prevented the wider introduction of plastics for these purposes hitherto has been their proneness to tear at points of stress concentration such as eyelets. Attempts have been made to thicken the material by folding it over at these points, or by the introduction of strain-taking bands of webbing woven through slots in the material, or enclosed in a folded-over seam, but these have not proved entirely effective, or they are wasteful of material.
The chief aim of my invention is to provide a method of reinforcing flexible plastic sheet at any desired points in a particularly effective and permanent manner.
According to my invention, at each point where an attachment is to be made for an eyelet, hook, button, handle or the like passing through the sheet, an area of textile material is applied to one or both sides of the plastic which is then fused at least partially into the textile material.
The textile material is preferably applied to both sides of the plastic sheet, and, where a number of spaced attachments are to be applied near the edge of the sheet, a continuous strip of textile material may be folded longitudinally over the edge.
The effect of the textile material is to receive the concentrated stress from the attachment and distribute it over a relatively Wide area.
An example of the application of my invention to the attachment of eyelets will now be described with reference to the accompanying drawings, in which:
Figure 1 shows a part of a plastic tarpaulin with a number of eyelets spaced round the edge; and
Figure 2 is a section on the line 2-2 of Figure 1 to a larger scale.
A tarpaulin 1 for use in covering goods exposed to the weather, such as in stores dumps, or on lorries, or for 2,801,948 Patented Aug. 6, 1957 the canopy, for example, of a troop-carrying vehicle, is made of a flexible sheet plastic, such as polythene.
Other thermo-plastic synthetic materials: may be used, but polythene has been found preferable as it softens at a relatively high temperature, considerably higher than any. likely to bev encountered in service, whereas it remains pliant and tough down to very low temperatures. It also has the added advantage of being transparent, so that stores contained within a tarpaulin of this material can be checked visually from outside, and in a troopcarrying vehicle employing such a tarpaulin as the canopy, the troops can see outside, and also, of course, light is admitted to the interior of the vehicle.
Around the edge of the sheet 1 is folded a strip of hessian 2, and heat and pressure are applied until the plastic fuses partially into the material of the hessian on each side. Brass eyelets of a known kind are applied at any convenient spacing, through holes punched in the composite material, each eyelet in the example shown being made up of two parts, a main body 3i and a closing disc 4 into which the shank of the body 3 is expanded.
To achieve maximum benefit from the invention, it is important that the plastic should not be fused too far through the hessian. The plastic has a relatively low co-eflicient of friction, whereas the hessian has a high coefficient, and the distribution of stress is only effective in so far as the two sides of the eyelet have a frictional engagement with the hessian. Accordingly the outer surface of the hessian should be free from the plastic.
It will be understood other attachments, such as hooks or handles, could be riveted through the reinforced parts of the plastic in a similar manner, the stress being distributed over a wide area of the plastic through the fibres of the Woven hessian. Where higher stresses are involved, canvas could be used in place of the hessian and if necessary the entire tarpaulin could use two or more thicknesses of flexible plastic instead of one.
In tests carried out with flexible polythene sheet, it was found that a given eyelet tore out the plain sheet under a load of approximately 40 lbs., whereas, when the sheet was reinforced with hessian in the region of the eyelet in the manner described, the same type of eyelet withstood a load of well over lbs.
Where the plastic is of lighter gauge, for example, in the application of the invention to bags for toilet articles, the reinforcing textile will be correspondingly lighter, and may be linen or cotton, or, in fact, any other suitable natural or synthetic fibre.
1. A method of attaching an eyelet to an article of flexible thermo-plastic sheet material, comprising the step of applying a piece of textile material to a surface of said thermo-plastic material and heating the thermoplastic material whilst applying pressure to both materials, thereby fusing the thermo-plastic material partially into the textile material so that the surface of said textile material remote from said surface of said thermoplastic material remains substantially free from the latter, and subsequently passing the eyelet through the resultant reinforced area and riveting it over.
2. A method of reinforcing an article of flexible thermo plastic sheet material, in the region of a point of stress concentration, comprising the step of applying a piece of textile material to a surface of said thermo-plastic material and partially fusing the thermo-plastic material into the textile material so that the surface of said textile material remote from said surface of said thermo-plastic material remains substantially free from the latter.
3. A method of reinforcing an article of flexible thermoplastic sheet material, according to claim 2, wherein said textile material is applied to both sides of said thermoplastic material.
. 3 I 4 A methodof reinforcing an article of flexible thermointo each piece of textile material so that the surfaces of plastic sheet material according to claim 3, in which a said textile material remote from said sides of said single piece of textile material is folded over the edge thermo-plastic material remain free from the latter.
of the thermoplastic material and serves as the reinforce'm'e'nt forlboth sides. 5 References Cited in the file of this patent 5.,Am1etho d of reinforcing an article of flexible thermo- UNITED STATES PATENTS plastic sheet material in the region of 'a point of stress concentration, comprising the step of applying a piece of 35 ii textile material to each side of the said thermo-plastic man material and partially fusing the therrno-plastic material 10