REACTIVE COMPATIBILIZED MULTI-LAYER HEAT-SHRINKABLE COATING
A multi-layer coating includes an adhesive layer, a tying layer, and a polyolefin sheet. A multi layer coating may include at least one tying layer interposed between and in contact with an adhesive layer and a heat-shrinkable polyolefin sheet.
1 . A heat-shrinkable coating for covering an outer surface of a pipe, the coating comprising
a heat-shrinkable polyolefin sheet,
a tying layer, and
an adhesive layer, wherein the tying layer is interposed between and in contact with the heat-shrinkable polyolefin sheet and the adhesive layer and the tying layer includes tying means for coupling the heat-shrinkable polyolefin sheet to the adhesive layer to retain the heat-shrinkable polyolefin sheet and the adhesive layer on the pipe and to minimize disbondment during aging.
2 . The coating of claim 1 , wherein tying means includes an amount of a reactively-modified polyolefin in the tying layer sufficient to provide adhesion to the polyolefin sheet and reactivity towards the adhesive layer so that contacting the adhesive layer to the tying layer creates covalent bonds between components of each layer.
3 . The coating of claim 2 , wherein tying means minimizes disbondment for a pipe with cathodic protection tested according to the procedure set forth in ASTM G42.
4 . The coating of claim 2 , wherein the adhesive layer comprises an adhesive selected from a group consisting of mastics, polyurethanes, polyamides, synthetic rubbers, and epoxies.
5 . The coating of claim 2 , wherein the heat-shrinkable polyolefin sheet comprises an irradiation cross-linked polyethylene, polypropylene or blend thereof and the adhesive layer comprises a polyamide and wherein contact between the tying layer and the adhesive layer includes the reactively-modified polyolefin covalently bound to the polyamide.
6 . The coating of claim 2 , wherein the heat-shrinkable polyolefin sheet shrinks by about 10% to about 60%, based on circumferential length, in response to being heated to at least about 60° C.
7 . The coating of claim 2 , wherein the heat-shrinkable polyolefin sheet, the tying layer, and the adhesive layer are combined to minimize disbondment according to ASTM G42.
8 . The coating of claim 2 , wherein
the heat-shrinkable polyolefin sheet comprises an irradiation cross-linked polyethylene, polypropylene or blend thereof providing about 10% to about 60% shrinkage, based on circumferential length, in response to being heated to at least about 60° C., the adhesive layer comprises a polyamide, and contact between the tying layer and the adhesive layer is characterized by the reactively-modified polyolefin covalently bonding with the polyamide to provide the coating with a peel adhesion to primer as determined according to EN12068 of greater than about 50 N/cm initially and throughout a period of aging at 80° C. for 100 days.
9 . The coating of claim 8 , wherein the heat-shrinkable polyolefin sheet is a woven heat-shrinkable polyolefin sheet.
10 . The coating of claim 9 further comprising an epoxy adhesive layer, wherein the epoxy adhesive layer is in contact with the adhesive layer on a surface of the adhesive layer opposite of the tying layer, forming in series, the heat-shrinkable polyolefin sheet, the tying layer, the adhesive layer, and the epoxy adhesive layer.
11 . The coating of claim 1 , wherein the heat-shrinkable polyolefin comprises an irradiation cross-linked polyethylene, polypropylene or blend thereof, the adhesive layer comprises a polyamide, and the tying layer comprises a reactively-modified polyolefin, the reactively-modified polyolefin providing adhesion to the heat-shrinkable polyolefin sheet and covalently bonding with the polyamide.
12 . The coating of claim 11 , further comprising a release liner, the release liner in contact with the adhesive layer, forming in series, the heat-shrinkable polyolefin sheet, the tying layer, the adhesive layer, and the release liner.
13 . The coating of claim 1 , further comprising
an epoxy adhesive layer and
a release liner, wherein
the epoxy adhesive layer is interposed between and in contact with the adhesive layer and the release liner forming in series the heat-shrinkable polyolefin sheet, the tying layer, the adhesive layer, the epoxy adhesive layer and the release liner,
the heat-shrinkable polyolefin sheet comprises an irradiation cross-linked polyethylene,
the adhesive layer comprises a polyamide, and
the tying layer comprises a reactively-modified polyolefin providing adhesion to the heat-shrinkable polyolefin sheet and covalent bonding with the polyamide of the adhesive layer.
14 . The coating of claim 13 , wherein the heat-shrinkable polyolefin sheet shrinks by about 10% to about 60%, based on circumferential length, in response to being heated to at least about 60° C.
15 . An apparatus for covering a pipe, the apparatus comprising
an adhesive layer in contact with a tying layer and the tying layer in contact with a heat-shrinkable polyolefin backing, forming in series, the adhesive layer, the tying layer, and the heat-shrinkable polyolefin backing, wherein
the tying layer adheres to the heat shrinkable polyolefin backing through at least polymer chain entanglements and van der Waals interactions and the tying layer bonds to the adhesive layer through at least covalent bonds formed between at least one component of the tying layer and at least one component of the adhesive layer, the adhesive layer, the tying layer, and the heat-shrinkable polyolefin sheet arranged and combined to minimize disbondment according to ASTM G 42.
16 . The apparatus of claim 15 , wherein the heat-shrinkable polyolefin backing is an irradiatively cross-linked heat-shrinkable polyolefin backing.
17 . The apparatus of claim 16 , wherein the irradiatively cross-linked heat-shrinkable polyolefin backing shrinks by about 10% to about 60%, based on circumferential length, in response to being heated to at least about 60° C.
18 . The apparatus of claim 17 , wherein the adhesive layer comprises an adhesive selected from a group consisting of mastics, polyurethanes, polyamides, synthetic rubbers and epoxies.
19 . The apparatus of claim 18 , wherein the heat-shrinkable polyolefin backing comprises a polyolefin selected from a group consisting of polyethylene, polypropylene and blends thereof.
20 . The apparatus of claim 19 , wherein the heat-shrinkable polyolefin backing is a woven heat-shrinkable polyolefin backing.
21 . The apparatus of claim 20 , wherein the heat-shrinkable polyolefin sheet, the tying layer, and the adhesive layer are adapted to cover the pipe upon shrinking to substantially seal the pipe from water and water vapors without sealing the pipe from passage of current.
22 . A joint-covering sleeve for covering an outer surface of a pipe, the joint-covering sleeve comprising
a polyolefin sheet,
a tying layer, and
an adhesive layer, wherein the trying layer is interposed between and in contact with the polyolefin sheet and the adhesive layer and the tying layer includes tying means for coupling the polyolefin sheet to the adhesive layer to retain the polyolefin sheet and the adhesive layer on a pipe.
23 . The joint-covering sleeve of claim 22 , wherein the tying means includes an amount of a reactively modified polyolefin dispensed in the tying layer to provide non-reactive compatibilization to the polyolefin sheet.
24 . The joint-covering sleeve of claim 22 , wherein contact between the tying layer and the adhesive layer causes the reactively modified polyolefin to bond with a polymer making up the adhesive layer.
25 . The joint-covering sleeve of claim 22 , wherein the tying means provides means for retaining the polyolefin sheet and the adhesive layer on the pipe so that the joint-covering sleeve resists cathodic disbondment according to ASTMG42.
26 . The joint-covering sleeve of claim 22 , wherein the polyolefin sheet comprises an irradiation cross-linked polymer.