Susceptor based bonding technique for plastic material utilizing oleaginous substance at the bonding interface

• US 4,067,765 A
• Filed: 09/17/1976
• Issued: 01/10/1978
• Est. Priority Date: 09/17/1976
• Status: Expired due to Term

• Current Assignee: William C. Heller Jr
• Original Assignee: William C. Heller Jr
• Inventors: Leatherman, Alfred F., Heller, William C. Jr.
• Primary Examiner(s): Drummond, Douglas J.
• Application Number:
  US05/724,101
• Time in Patent Office: 480 Days
• Field of Search: 156/272, 156/380, 219/10.41, 219/10.43, 219/10.53, 219/10.81, 252/510, 252/511, 252/513
• US Class Current: 156/272.4
• CPC Class Codes: B29C 65/1412 Infrared [IR] radiation
• CPC Class Codes: B29C 65/1477 making use of an absorber or impact modifier B29C65/1677 takes precedence
• CPC Class Codes: B29C 65/148 placed at the interface
• CPC Class Codes: B29C 65/1483 coated on the article
• CPC Class Codes: B29C 65/34 using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
• CPC Class Codes: B29C 65/3476 being metallic
• CPC Class Codes: B29C 65/3484 being non-metallic
• CPC Class Codes: B29C 65/3612 comprising fillers
• CPC Class Codes: B29C 65/3668 characterised by the means for supplying heat to said heated elements which remain in the join, e.g. special induction coils
• CPC Class Codes: B29C 65/368 with a polymer coating
• 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 66/43 Joining a relatively small portion of the surface of said articles B29C66/45 takes precedence
• 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 66/73941 characterised by the materials of both parts being thermosets
• CPC Class Codes: B29C 66/8122 characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• CPC Class Codes: B29C 66/8181 characterised by the cooling constructional aspects
• CPC Class Codes: B29C 66/83221 cooperating reciprocating tools, each tool reciprocating along one axis
• 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 2905/10 : Copper
• CPC Class Codes: B29K 2995/0008 : Magnetic or paramagnetic

Abstract

A film of an oleaginous substance is interposed between the surfaces of plastic elements to be joined by a thermal bond. The heat necessary for bonding is obtained by the incorporation of heat generating particles in the bond region, either in the plastic element or in the film. The particles are indirectly heatable by a high frequency alternating magnetic field or other suitable field. This provides a rapid and efficient heating of the surfaces to the bonding temperature, with the oleaginous substance enhancing the bonding action and the properties of the bond.

Claims

1. A method for the thermal bonding of first and second plastic elements over a joinder interface portion comprising:

interposing between the joinder interface portions a film of an oleaginous substance;

juxtapositioning the elements so that the interface portions thereof to be joined are contiguous to form with the interposed film a joinder region including the film and the plastic material of such elements;

incorporating within the joinder region heat generating particles generating heat in the particles upon exposure to a high frequency energy field;

exposing the heat source particles to the high frequency energy field to heat the plastic material in the contiguous joinder interface portions to thermal bonding temperature; and

retaining the joinder interface portions in intimate contact until a thermal bond is formed.

2. The method of claim 1 further defined as including a step of applying pressure over the joinder interface portions with the joinder interface portions at the bonding temperature.

3. The method of claim 2 including the applying of said pressure in the presence of said field.

4. The method of claim 1 including the step of cooling the joinder interface portion to accelerate formation of the bond.

5. The method of claim 1 wherein said interposing step includes providing a material selected from the group consisting of petroleum based oils, the lipids and grease.

6. The method of claim 1 wherein said step of incorporating heat source particles includes employing particles activated by exposure to a high frequency alternating magnetic field and said exposing step includes the creating of a high frequency alternating magnetic field.

7. The method of claim 6 wherein said exposing step is further defined as subjecting the contiguous joinder portions to a magnetic field having a frequency of from 0.4 to 5000 megahertz, and said particles are selected to generate heat as a result of hysteresis losses.

8. The method of claim 7 further defined as subjecting the contiguous joinder portions to a magnetic field having a frequency of from 2 to 30 megahertz.

9. The method of claim 6 further defined as incorporating a particulate susceptor comprising nonconductive ferromagnetic oxides.

10. The method of claim 9 further defined as incorporating particles selected from a class consisting of gamma Fe₂ O₃ and Fe₃ O₄, in the plastic material.

11. The method of claim 9 further defined as incorporating susceptor particles selected from a class consisting of gamma Fe₂ O₃ and Fe₃ O₄, and said exposing steps include creating a magnetic field having a frequency of from 2 to 30 megahertz.

12. The method of claim 1 further defined as incorporating susceptor particles heatable upon exposure to radiant energy and wherein said exposing step includes forming of a radiant energy field.

13. The method of claim 1 wherein the incorporating step is further defined as dispersing a particulate susceptor heatable upon exposure to an energy field in at least the contiguous joinder portion of at least one of the first and second materials.

14. The method of claim 13 further defined as dispersing a nonconductive ferromagnetic oxide particulate susceptor in the thermoplastic material forming the joinder portion.

15. The method of claim 13 further defined as dispersing a nonconductive ferromagnetic oxide susceptor particle having a particle size between 0.01 microns and 25 microns.

16. The method of claim 1 including the further step of dispersing plastic granules in the oleaginous film and selected of a plastic resulting in thermal bonding to said elements in the presence of said field.

17. The method of claim 16 further defined as dispersing susceptor particles into the plastic granules.

18. A method for the thermal bonding of first and second thermoplastic elements over an interface joinder portion comprising:

forming a mixture of an oleaginous substance and solid plastic particles bondably compatible with said elements, interposing a film of said mixture at the interface joinder portion, incorporating in the interface joinder portion dispersed susceptor particles heatable upon exposure to a high frequency energy field; and

exposing the susceptor particles to the energy field to heat the interface joinder portion including said film and plastic particles to bonding temperature to form an integral thermal bond between the elements and the plastic particles.

19. The method of claim 18 including the further step of mixing said susceptor particles into said mixture of oleaginous material and solid plastic particles.

20. The method of claim 18 including the step of embedding said susceptor particles into said plastic particles and then forming said mixture.

21. The method of claim 20 wherein said susceptor particles are of a size within the range of 0.01 to 25 microns.