HEATABLE STRATIFIED MATERIAL AND MANUFACTURING METHOD THEREFOR

• US 3,802,985 A
• Filed: 01/06/1972
• Issued: 04/09/1974
• Est. Priority Date: 01/06/1972
• Status: Expired due to Term

• Current Assignee: Alfred F. Leatherman
• Original Assignee: Alfred F. Leatherman
• Inventors: Leatherman, Alfred F.
• Primary Examiner(s): Drummond, Douglas J.
• Application Number:
  US05/215,855
• Time in Patent Office: 824 Days
• Field of Search: 156/272,273,242,244 264/171,211
• US Class Current: 156/244.25
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: B29C 48/07 Flat, e.g. panels
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/307 specially adapted for bringing together components, e.g. melts within the die
• CPC Class Codes: B29C 48/3363 using a layered die, e.g. stacked discs
• CPC Class Codes: B29C 65/1425 Microwave radiation
• CPC Class Codes: B29C 65/3656 being a layer of a multilayer part to be joined, e.g. for joining plastic-metal laminates
• CPC Class Codes: B29C 65/3676 being metallic
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/1162 Single bevel to bevel joints, e.g. mitre joints
• CPC Class Codes: B29C 66/1222 comprising at least a lapped joint-segment
• CPC Class Codes: B29C 66/1224 comprising at least a butt joint-segment
• CPC Class Codes: B29C 66/1226 comprising at least one bevelled joint-segment
• CPC Class Codes: B29C 66/24221 being circular B29C66/51 takes precedence
• CPC Class Codes: B29C 66/53461 joining substantially flat covers and/or substantially flat bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/542 joining hollow covers or hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/5432 joining hollow covers and hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/545 : one hollow-preform being placed inside the other
• CPC Class Codes: B29C 66/612 : Making circumferential joints
• CPC Class Codes: B29C 66/71 : characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/73921 : characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/8322 : Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/83413 : cooperating rollers, cylinders or drums
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2025/06 : PS, i.e. polystyrene
• CPC Class Codes: B29K 2027/08 : PVDC, i.e. polyvinylidene chloride
• CPC Class Codes: B29K 2033/20 : PAN, i.e. polyacrylonitrile
• CPC Class Codes: B29K 2995/0008 : Magnetic or paramagnetic
• CPC Class Codes: B32B 1/08 : Tubular products
• CPC Class Codes: B32B 2264/102 : Oxide or hydroxide
• CPC Class Codes: B32B 2307/20 : having particular electrical or magnetic properties, e.g. piezoelectric
• CPC Class Codes: B32B 2597/00 : Tubular articles, e.g. hoses, pipes
• CPC Class Codes: B32B 27/08 : of synthetic resin

Abstract

A stratified thermoplastic material having a susceptor in one of the layers is formed by coextrusion. The susceptor is heatable by indirectly applied energy so that article parts formed of the stratified material may be thermally joined together to form plastic articles.

Claims

1. A method of forming a stratified material having an inductively heatable layer by coextrusion through a layer forming die, said method comprising the steps of:

providing a plurality of fusible thermoplastic compositions at first locations removEd from the layer forming die;

moving the compositions from the first locations toward the die, the movement of at least one of the compositions being accompanied by an agitation thereof;

incorporating in the one composition, during its movement toward the die and by means of its agitation, a particulate susceptor in a size range of submicron to 20 microns and selected from a material class consisting of the oxides of iron and chromium having ferromagnetic properties;

heating the compositions to a malleable and fusible state during the movement; and

forcing the compositions through the die into intimate contact with each other while in the malleable and fusible state to form joined layers of the compositions and the stratified material.

2. The method according to claim 1 wherein pressure is applied to the layers to assist in intimately joining them together.

3. The method according to claim 1 including an initial step of formulating each of the thermoplastic compositions to possess a property desired in the formed stratified material.

4. The method according to claim 3 wherein another of the thermoplastic compositions is rendered at least partially opaque, thereby to mask the composition layer containing the particulate susceptor in the finished stratified material.

5. The method according to claim 3 wherein at least one of the external layer compositions of the stratified material is formulated to be thermally joinable responsive to the heat generated in the particulate susceptor.

6. The method according to claim 1 wherein the incorporation step is further defined as incorporating the particulate susceptor in quantities of about 1 percent or more by weight with respect to the one composition.

7. The method according to claim 6 wherein the incorporation step is further defined as incorporating the particulate susceptor in quantities of up to 30 percent by weight with respect to the one composition.

8. The method according to claim 1 wherein the incorporation step is further defined as uniformly dispersing the particulate susceptor in one of the compositions.

9. The method according to claim 1 further defined as continuously carrying out the steps of the method.

10. The method according to claim 1 wherein the particulate susceptor is incorporated in the one of the compositions by directly mixing particles of the susceptor in the composition during its movement.

11. The method according to claim 1 including the initial step of incorporating the particulate susceptor in a predetermined quantity of the one composition and thereafter incorporating the quantity so treated in the moving composition.

12. The method according to claim 1 wherein the incorporation step is further defined as intermittently dispersing the particulate susceptor in the one composition during the movement of the composition to disperse the susceptor material in selected areas of the one composition.

13. The method according to claim 1 wherein the step of forcing the compositions through a die is further defined as continuously forcing at least one layer through the die while intermittently forcing another layer through the die to provide the other layer at selected areas of the first layer.

14. The method according to claim 13 wherein the step of forcing the compositions through a die is further defined as intermittently forcing the layer incorporating the susceptor through the die.

15. The method according to claim 14 wherein the step of forcing the compositions through a die is further defined as coordinately intermittently forcing one of the layers through the die and varying the thicknesses of the layers of the stratified material to maintain the overall thickness of the stratified material relatively constant.

16. The method according to claim 1 further defined as containing the additional step of cooling the stratified material.