# US 4,396,449 A · Cutting and sealing process for thermoplastic materials

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- Number: US 4,396,449 A
- Document ID: US4396449A
- Status: Granted
- Kind: A
- Application number: 06/310,935
- Filed: 1981-10-13
- Granted: 1983-08-02
- Earliest claimed: 1981-10-13
- Assignees: The Dow Chemical Company
- Inventors: Dennis R. Tumminia
- Web page: https://patentgrep.com/patent/US4396449A

## CPC

- B29C 66/137: {Beaded-edge joints or bead seals (for sealing or securing package folds or closures B65B51/24)}
- B29C 65/18: using heated tools
- B29C 65/222: {comprising at least a single heated wire}
- B29C 65/226: {characterised by the cross-section of said heated wire, resistive ribbon, resistive band or resistive strip, e.g. being triangular}
- B29C 65/7433: {the tool being a wire}
- B29C 66/43: {Joining a relatively small portion of the surface of said articles (B29C66/45 takes precedence)}
- B29C 66/73711: {oriented}
- B29C 66/73921: {characterised by the materials of both parts being thermoplastics}
- B29C 66/81411: {characterised by its cross-section, e.g. transversal or longitudinal, being non-flat}
- B29C 66/81417: {being V-shaped}
- B29C 66/91421: {of the joining tools}
- B29C 66/71: {characterised by the composition of the plastics material of the parts to be joined (welding bar compositions B29C65/125)}
- B29C 66/7234: {comprising a barrier layer}
- B29C 66/73712: {mono-axially}
- B29C 66/934: {by controlling or regulating the speed}
- Y10T 156/1054: and simultaneously bonding [e.g., cut-seaming]
- Y10T 156/1313: Cutting element simultaneously bonds [e.g., cut seaming]
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method for reducing wax build-up on a sealing equipment where a heated element, such as a hot wire, cuts through and seals adjacent layers of thermoplastic material containing thickened thermoplastic sections. The wax build-up is related to the contact between the cutting and sealing wire and the thermoplastic material. The improvement results from a proper shaping of the cutting and sealing wire, by regulating the rising height and profiling of the wire through the film and thickened sections, and by employing relatively high wire travel speeds whereby it is possible to take advantage of the shrink back characteristics resulting from the orientation already built into the thermoplastic material, so that minimum contact between the wire and the thermoplastic material is realized.

## Claims

### Claim 1

A process for cutting multiple plies of oriented thermoplastic material having thickened sections and simultaneously sealing severed margins thereof comprising the steps of:
(a) clamping the material adjacent the area thereof to be cut and sealed;
(b) selecting a cutting and sealing element with an elongated cross-section having a height to width ratio from about 5:1 to 2:1, capable of being heated and for a length at least as long as the section to be cut and sealed;
(c) heating said element to a temperature sufficient to cut and seal said material;
(d) biasing the travel of said element so that an engaging edge thereof passes through the thickened section for a distance no less than that through the rest of said material and without the entire element passing beyond the last ply to be engaged by the element but sufficient to sever all such plies; and
(e) permitting the severed plies of material to retract a given distance and form a sealed edge.

### Claim 2 (depends on 1)

The process of claim 1 wherein said element at its width defining a heated cutting edge for engaging the thermoplastic material to sever the same.

### Claim 3 (depends on 2)

The process of claim 2 wherein said cutting edge is generally rounded.

### Claim 4 (depends on 2)

The process of claim 2 wherein said cutting edge is generally pointed.

### Claim 5 (depends on 2)

The process of claim 2 wherein the height to width ratio of said element is about 3:1.

### Claim 6 (depends on 1)

The process of claim 1 wherein said element is outwardly biased adjacent said thickened sections so that after said material is severed, the element adjacent the thickened sections is further from the film plies than is otherwise generally the case.

### Claim 7 (depends on 6)

The process of claim 6 wherein the outwardly biased part of the element is biased at least twice the distance at another less thick section of the material.

### Claim 8 (depends on 7)

The process of claim 7 wherein the heat discharged from said element and the speed at which the element engages the film plies is selected such that a first severed ply shrinks from contact with said element prior to said elements severing of the next adjacent ply.

### Claim 9 (depends on 8)

The method of claim 8 wherein all plies are of the same material composition.

### Claim 10

In an apparatus for cutting multiple plies of oriented thermoplastic material having thickened sections and simultaneously sealing severed margins thereof,
(a) a material supporting surface containing at least one cavity;
(b) means for clamping said material across said cavity;
(c) an elongated cutting and sealing element having a height to width ratio of about 5:1 to 2:1 and located within said cavity;
(d) means for moving said element into contact with and past said material;
(e) means for biasing said element such that the material engaging edge thereof passes through the thickened section a distance further than that through other sections of said material; and
(f) means for heating said elements and driving its engaging edge quickly through said film plies to sever the seal the same.

### Claim 11 (depends on 10)

The apparatus of claim 10 wherein said element has a height to width ratio of about 3:1.