Method and apparatus for producing spiral wound container

Claim 5

The method set forth in claim 2 comprising the additional steps of applying a continuous tape, having a continuous layer of a slip and sanitary coating on the inner surface and a continuous layer of a heat sealable thermoplastic material coated on the outer surface, to the inner surface of said barrier ply along the marginal trailing edge of said barrier ply, as said barrier ply is wound on said mandrel, with a portion of said outer surface of said tape in contact with the inner surface of said barrier ply and the remaining portion of said outer surface of said tape extending outwardly from said trailing edge for receiving the leading edge of the following turn of said barrier ply wound on said mandrel.

Claim 6

The method set forth in claim 3 in which the winding angle for each of said body plies is about 27*.

Claim 7

The method set forth in claim 3 comprising heating substantially the entire outer paper surface of the outermost one of said body plies just prior to contacting thereof by said label ply strip thereby to improve the bonding of said inner thermoplastic layer of said label ply to said outer body ply and to reduce substantially the moisture content of the paper in said outer body ply.

Claim 8

The method set forth in claim 5 in which said step of heating substantially the entire outer paper surface of the outermost one of said body plies is effected by contacting said outer paper surface with a gas flame.

Claim 9

The method set forth in claim 3 in which each of said heating steps is effected by contacting the surface to be heated with a gas flame.

Claim 10

Apparatus for making spirally wound can bodies having an inner barrier ply formed as a laminate of a self-supporting, substantially pinhole free, thin metal foil, a thin, continuous layer of a slip and sanitary coating on the inner surface of said foil, at least one body ply overlying said barrier ply and comprising a first outer paper can stock layer and a continuous layer of a heat sealable thermoplastic material coated on the inner surface of said first outer paper can stock layer, and a label ply formed as a laminate having an inner heat sealable thermoplastic layer; said apparatus comprising: a. a tube winding mandrel; b. means for winding a strip of said barrier ply on said mandrel to form a first continuous tube with said slip and sanitary coating contacting said mandrel and with a leading edge portion of each turn butting a trailing edge portion of the previous turn; c. means for applying a continuous tape, having a continuous layer of a slip and sanitary coating on the inner surface and a continuous layer of a heat sealable thermoplastic material on the outer surface, to the trailing edge of said barrier ply as said barrier ply is wound onto said mandrel and for bringing the leading edge of the following turn into contact with said tape for forming a tape seal across said butting edges; d. first flame burner means arranged to direct a flame onto the leading and trailing edge portions of butting windings of said barrier ply strips to heat the same to a heat sealing temperature after said strip contacts said mandrel and to heat seal said tape to said butting windings across said butting edges; e. means for winding a strip of said body ply on said mandrel and over said barrier ply tube to form a second continuous tube and with said thermoplastic coating of said body ply being disposed to contact said barrier ply; f. meanS for skiving the side edges of said body ply prior to winding thereof on said mandrel to provide tapered paper surfaces at each edge of said body ply, said body ply, when wound, being arranged so that the thermoplastic coating at the leading edge portion of said body ply overlies the tapered paper surface at the trailing edge portion of the preceding turn of said body ply; g. second flame burner means for heating the entire width of said thermoplastic layer of said body ply to a heat sealing temperature just prior to contact thereof with the underlying tube on said mandrel thereby to heat seal substantially the entire width of said body ply to said barrier ply and to heat seal said leading edge portion of said thermoplastic coating of said body ply to said underlying tapered paper surface, said second flame burner means comprising a plurality of individual burners each disposed transversely across said body ply strip adjacent the point of contact thereof with the underlying tube on said mandrel; h. means for winding a strip of said label ply on said mandrel to form a third continuous tube as the outermost ply of said can body, said label ply being disposed with said inner heat sealable layer thereof disposed toward said mandrel and with a leading edge portion of said label ply being arranged to overlap a trailing edge portion of the preceding turn of said label ply; and i. third flame burner means for heating substantially the entire width of said inner thermoplastic layer of said label ply to a heat sealing temperature just prior to contact thereof with the immediately underlying tube on said mandrel thereby to heat seal said label ply to said immediately underlying tube across substantially the entire width of said label ply, said heating of said inner thermoplastic layer of said label ply also serving to heat seal together said overlapping edge portion of said label ply.

Claim 11

Apparatus for making spirally wound can bodies having an inner barrier ply formed as a laminate of a self-supporting, substantially pinhole free, thin metal foil, a thin, continuous layer of a slip and sanitary coating on the inner surface of said foil, at least one body ply overlying said barrier ply and comprising a first outer paper can stock layer and a continuous layer of a heat sealable thermoplastic material coated on the inner surface of said first outer paper can stock layer, and a label ply formed as a laminate having an inner heat sealable thermoplastic layer; said apparatus comprising: a. a tube winding mandrel; b. means for winding a strip of said barrier ply on said mandrel to form a first continuous tube with said slip and sanitary coating contacting said mandrel and with a leading edge portion of each turn butting a trailing edge portion of the previous turn; c. means for applying a continuous tape, having a continuous layer of a slip and sanitary coating on the inner surface and a continuous layer of a heat sealable thermoplastic material on the outer surface, to the trailing edge of said barrier ply as said barrier ply is wound onto said mandrel and for bringing the leading edge of the following turn into contact with said tape for forming a tape seal across said butting edges; d. first flame burner means arranged to direct a flame onto the leading and trailing edge portions of butting windings of said barrier ply strips to heat the same to a heat sealing temperature after said strip contacts said mandrel and to heat seal said tape to said butting windings across said butting edges; e. means for winding a strip of said body ply on said mandrel and over said barrier ply tube to form a second continuous tube and with said thermoplastic coating of said body ply being disposed to contact said barrier ply; f. meanS for skiving the side edges of said body ply prior to winding thereof on said mandrel to provide tapered paper surfaces at each edge of said body ply, said body ply, when wound, being arranged so that the thermoplastic coating at the leading edge portion of said body ply overlies the tapered paper surface at the trailing edge portion of the preceding turn of said body ply; g. second flame burner means for heating the entire width of said thermoplastic layer of said body ply to a heat sealing temperature just prior to contact thereof with the underlying tube on said mandrel thereby to heat seal substantially the entire width of said body ply to said barrier ply and to heat seal said leading edge portion of said thermoplastic coating of said body ply to said underlying tapered paper surface, said second flame burner means comprising a plurality of individual burners each disposed transversely across said body ply strip adjacent the point of contact thereof with the underlying tube on said mandrel; h. means for winding a strip of said label ply on said mandrel to form a third continuous tube as the outermost ply of said can body, said label ply being disposed with said inner heat sealable layer thereof disposed toward said mandrel and with a leading edge portion of said label ply being arranged to overlap a trailing edge portion of the preceding turn of said label ply; and i. third flame burner means for heating substantially the entire width of said inner thermoplastic layer of said label ply to a heat sealing temperature just prior to contact thereof with the immediately underlying tube on said mandrel thereby to heat seal said label ply to said immediately underlying tube across substantially the entire width of said label ply, said heating of said inner thermoplastic layer of said label ply also serving to heat seal together said overlapping edge portion of said label ply.

Claim 12

Apparatus as set forth in claim 8 comprising fourth flame burner means arranged to direct an axially extending flame onto the outer body ply surface at a point just prior to contact thereof by said label ply, the axial length of said axially extending flame being sufficient that substantially the entire outer body ply surface is heated thereby.