Heat-sealing system for plastic containers

Claim 3

The apparatus of claim 1 in which said channel is generally U-shaped and is defined by a top wall and two parallel side walls.

Claim 4

The apparatus of claim 1 in which the engagement of the fastener end by said channel creates a pressure differential between the fastener end and said regional area of the plastic sheet adjacent the end such that the fastener end is at a lower pressure than said regional area and in which said means for heating includes a heating element for heating said regional area during the movement of said pressure and sealing means toward each other, said pressure differential creating a flow of plastic material into said channel and across the end of the fastener straddled thereby during the engagement of said pressure and sealing means with the plastic sheet.

Claim 5

The apparatus of claim 3 including a means for separating the fastener end from portions of the regional area of the plastic sheet material adjacent said end following the flow of the heated plastic material into said channel and across the end of the fastener straddled thereby.

Claim 6

The apparatus of claim 2 in which said channel is generally U-shaped and is defined by a top wall and two parallel side walls.

Claim 7

The apparatus of claim 2 in which said channel is generally U-shaped and is defined by a top wall and two side walls, said side walls providing at least one enlarged channel end portion and a central land area to cause said heated plastic to flow into the fastener end straddled by said enlarged channel end portion.

Claim 8

The apparatus of claim 6, further including a separating means supported by said central land area, said separating means being adapted to divide said regional area of the plastic sheet material adjacent said end into two portions following the flow of the heated plastic material into said channel.

Claim 9

ApparatUs for forming a bead seal at the junction of the end of an openable and reclosable fastener with a side wall of a plastic container, which apparatus comprises: a. a sealing bar for applying heat to said junction and to a regional area of the plastic container adjacent said junction for heating said regional area and said junction to a plastic flowable condition; b. a pressure bar for applying pressure to said junction and to said regional area of the plastic container adjacent thereto, said pressure bar and said sealing bar being movable toward each other to engage the opposite sides of the container; and c. a channel located on one of said pressure and sealing bars for engagement with the fastener end at said junction and adapted to straddle and slightly pinch the fastener end when said pressure bar and sealing bar are in engagement with the plastic container to cause plastic flow into said fastener end, thereby forming a bead seal at said junction.

Claim 10

ApparatUs for forming a bead seal at the junction of the end of an openable and reclosable fastener with a side wall of a plastic container, which apparatus comprises: a. a sealing bar for applying heat to said junction and to a regional area of the plastic container adjacent said junction for heating said regional area and said junction to a plastic flowable condition; b. a pressure bar for applying pressure to said junction and to said regional area of the plastic container adjacent thereto, said pressure bar and said sealing bar being movable toward each other to engage the opposite sides of the container; and c. a channel located on one of said pressure and sealing bars for engagement with the fastener end at said junction and adapted to straddle and slightly pinch the fastener end when said pressure bar and sealing bar are in engagement with the plastic container to cause plastic flow into said fastener end, thereby forming a bead seal at said junction.

Claim 11

The apparatus of claim 8 in which said channel is generally U-shaped and is defined by a top wall and two parallel side walls.

Claim 12

The apparatus of claim 8 in which said channel is shaped to create a pressure differential between said fastener end and said regional area of the plastic sheet adjacent said end such that said fastener end is at a lower pressure than said regional area to produce said flow of plastic.

Claim 13

The apparatus of claim 9, further including separator means for dividing said regional area of the plastic container adjacent said end into two portions following said flow of heated plastic material into said fastener end, thereby forming adjacent but separated heat-sealed portions.

Claim 14

The apparatus of claim 9 in which said channel is generally U-shaped and is defined by a top wall and two parallel side walls.

Claim 15

The apparatus of claim 12 in which said channel has at least one enlarged channel end portion and a central land area to cause said heated plastic to flow into the fastener end straddled by said enlarged channel end portion.

Claim 16

The apparatus of claim 13 further including a separating means supported by said central land area, said separating means being adapted to divide said regional area of the plastic sheet material adjacent said end into two portions following said flow of heated plastic material into said fastener end.

Claim 17

In an apparatus for forming containers having a slideless fastener closure across one end thereof, said container having first and second walls formed from a continuous length of plastic stock material, said material carrying on adjacent portions of said first and second walls corresponding mating portions of said fastener, said fastener portions extending the length of said stock material, sealing means for receiving and supporting said stock material, pressure means movable with respect to said sealing means for gripping said stock material, heating means within said sealing means for heating at least a portion of the material gripped between said sealing and pressure means thereby to weld said first and second walls together to form a container side, the improvement comprising, channel means formed in at least one of said sealing and pressure means for forming a bead seal in said fastener, said channel means being so located as to engage that part of said fastener which is located between said sealing and pressure means, said channel being shaped to straddle and slightly pinch said fastener, and to produce a pressure differential between said fastener and the regional area of said material adjacent thereto, whereby the heating of said material causes a plastic flow into said fastener at the junction of said container side and said fastener to produce said bead seal.

Claim 18

In an apparatus for forming containers having a slideless fastener closure across one end thereof, said container having first and second walls formed from a continuous length of plastic stock material, said material carrying on adjacent portions of said first and second walls corresponding mating portions of said fastener, said fastener portions extending the length of said stock material, sealing means for receiving and supporting said stock material, pressure means movable with respect to said sealing means for gripping said stock material, heating means within said sealing means for heating at least a portion of the material gripped between said sealing and pressure means thereby to weld said first and second walls together to form a container side, the improvement comprising, channel means formed in at least one of said sealing and pressure means for forming a bead seal in said fastener, said channel means being so located as to engage that part of said fastener which is located between said sealing and pressure means, said channel being shaped to straddle and slightly pinch said fastener, and to produce a pressure differential between said fastener and the regional area of said material adjacent thereto, whereby the heating of said material causes a plastic flow into said fastener at the junction of said container side and said fastener to produce said bead seal.

Claim 19

The apparatus of claim 15, wherein said channel means is formed in said pressure means, said channel being parallel to said fastener.

Claim 20

The apparatus of claim 16, wherein said pressure means comprises a pressure bar arranged gEnerally transverse to the length of said stock material, said pressure bar cooperating with said sealing and heating means to form a container side generally perpendicular to the length of said fastener.

Claim 21

The apparatus of claim 17, wherein said channel means comprises first and second side walls and a bottom wall defining a continuous generally U-shaped cross-section adapted to receive said fastener, said pressure bar and said channel cooperating to produce a plastic flow into said fastener at its junction with said container side.

Claim 22

The apparatus of claim 17, wherein said channel means comprises first and second side walls and a bottom wall defining a discontinuous, generally U-shaped cross-section, the discontinuous portion of said channel defining a land area which produces a restriction at the middle of said channel, said pressure bar and said channel cooperating to produce a flow of plastic into said fastener at its junction with said container side.

Claim 23

The apparatus of claim 17, further including cutter means for dividing said sheet material along the weld forming said container side, whereby a single weld forms a container side for each of two containers.

Claim 24

Apparatus for forming a plastic bead seal at a junction between an interlocking, openable and reclosable plastic fastener and a sheet of plastic material to which said fastener is secured, comprising: a. means for supporting the junction of said fastener and the regional area of the plastic sheet material adjacent said junction; b. means for applying pressure to said junction and to said sheet material in said regional area; c. means for moving said pressure applying means and said supporting means toward each other to engage opposite surfaces of said fastener and sheet material; d. means for heating at least one of said pressure applying and supporting means; and e. means producing a pressure differential between said fastener and said sheet material in said regional area to cause a plastic flow into said junction to form a sealing bridge at said junction between said fastener and said sheet material.

Claim 25

Apparatus for forming a plastic bead seal at a junction between an interlocking, openable and reclosable plastic fastener and a sheet of plastic material to which said fastener is secured, comprising: a. means for supporting the junction of said fastener and the regional area of the plastic sheet material adjacent said junction; b. means for applying pressure to said junction and to said sheet material in said regional area; c. means for moving said pressure applying means and said supporting means toward each other to engage opposite surfaces of said fastener and sheet material; d. means for heating at least one of said pressure applying and supporting means; and e. means producing a pressure differential between said fastener and said sheet material in said regional area to cause a plastic flow into said junction to form a sealing bridge at said junction between said fastener and said sheet material.

Claim 26

The apparatus of claim 21, wherein said means producing a pressure differential comprises channel means in at least one of said pressure applying and supporting means, said channel means being shaped to straddle said fastener, whereby plastic flow is directed from said regional area adjacent said junction and from said fastener toward said junction.

Claim 27

Apparatus for forming a liquid-tight junction between the end of a two-part, interlocking plastic fastener and the edge of a sheet of plastic material to which said fastener is secured, comprising: a. support means for supporting the end of said fastener and the edge of said plastic sheet material; b. pressure means for applying pressure to the end of said fastener and along the edge of said sheet material; c. means for moving said support means and said pressure means toward each other to engage said fastener and sheet material; d. means for heating at least one of said pressure means or support means; and e. bead forming means for producing, when said fastener and said sheet material are heated and under pressure, a pressure differential between said fastener and said sheet material to cause a plastic flow toward the junction between said fastener and said sheet material to form a bead of plastic at said junction which, upon cooling of said plastic, provides a liquid-tight seal.

Claim 28

Apparatus for forming a liquid-tight junction between the end of a two-part, interlocking plastic fastener and the edge of a sheet of plastic material to which said fastener is secured, comprising: a. support means for supporting the end of said fastener and the edge of said plastic sheet material; b. pressure means for applying pressure to the end of said fastener and along the edge of said sheet material; c. means for moving said support means and said pressure means toward each other to engage said fastener and sheet material; d. means for heating at least one of said pressure means or support means; and e. bead forming means for producing, when said fastener and said sheet material are heated and under pressure, a pressure differential between said fastener and said sheet material to cause a plastic flow toward the junction between said fastener and said sheet material to form a bead of plastic at said junction which, upon cooling of said plastic, provides a liquid-tight seal.

Claim 29

The apparatus of claim 23, wherein said bead-forming means comprises means for causing plastic flow along the said edge of said sheet material toward said fastener.

Claim 30

The apparatus of claim 23, wherein said bead forming means comprises means for causing plastic flow along said edge of said sheet material toward said fastener and along the length of said fastener toward said junction between the fastener and the sheet material.