Welding techniques for polymer or polymer composite components

Abstract

A process for bonding a semi-crystalline or crystalline thermoplastic polymer to a thermosetting polymer component, the process including selecting compatible semi-crystalline thermoplastic polymer and uncured thermosetting polymer components wherein the curing temperature of the uncured thermosetting polymer components is above the melting temperature of the semi-crystalline thermoplastic polymer. The process includes locating the thermoplastic polymer in contact with the uncured thermosetting polymer component and heating the thermoplastic polymer and uncured thermosetting polymer or thermosetting polymer composite component to the curing temperature of the thermosetting polymer, where the uncured thermosetting polymer components and the thermoplastic polymer are able to at least partly interpenetrate before the thermosetting polymer cures. The thermoplastic polymer and cured thermosetting polymer component are then cooled such that the thermoplastic polymer is very strongly bonded to the cured thermosetting polymer component.

1 . A process for bonding a semi-crystalline or crystalline thermoplastic polymer to a thermosetting polymer component, the process including: 
 selecting compatible semi-crystalline thermoplastic polymer and uncured thermosetting polymer components wherein the curing temperature of the uncured thermosetting polymer component is above the melting temperature of the semi-crystalline thermoplastic polymer,    locating the thermoplastic polymer in contact with the uncured thermosetting polymer component;    heating the thermoplastic polymer and uncured thermosetting polymer or thermosetting polymer composite component to the curing temperature of the thermosetting polymer, where the uncured thermosetting polymer components and the thermoplastic polymer are able to at least partly interpenetrate before the thermosetting polymer cures; and    cooling the thermoplastic polymer and cured thermosetting polymer component such that the thermoplastic polymer is very strongly bonded to the cured thermosetting polymer component.    
     
     
         2 . A process according to  claim 1 , wherein the thermosetting polymer component is a thermosetting polymer.  
     
     
         3 . A process according to  claim 1 , wherein the thermosetting polymer component is initially uncured and forms part of a thermosetting polymer composite.  
     
     
         4 . A process according to  claim 3 , wherein the thermoplastic polymer and the uncured thermosetting polymer part of the thermosetting polymer composite are able to, when heated, at least partly interpenetrate before the thermosetting polymer cures, thereby bonding the thermoplastic polymer to the thermosetting polymer composite.  
     
     
         5 . A process for bonding a semi-crystalline or crystalline thermoplastic polymer to a thermosetting polymer component, the process including: 
 selecting compatible semi-crystalline thermoplastic polymer and uncured thermosetting polymer components wherein the uncured thermosetting polymer component can migrate into the semi-crystalline thermoplastic polymer at or below the curing temperature of the thermosetting component;    locating the thermoplastic polymer in contact with the uncured thermosetting polymer component;    heating the thermoplastic polymer and uncured thermosetting polymer or thermosetting polymer composite component to the curing temperature of the thermosetting polymer, where the uncured thermosetting polymer components and the thermoplastic polymer are able to at least partly interpenetrate before the thermosetting polymer cures; and    cooling the thermoplastic polymer and cured thermosetting polymer component such that the thermoplastic polymer is very strongly bonded to the cured thermosetting polymer component.    
     
     
         6 . A process according to  claim 5 , wherein the curing temperature of the thermosetting component is below the melting temperature of the semi-crystalline thermoplastic polymer.  
     
     
         7 . A process according to  claim 5  or  6 , wherein the thermosetting polymer component is a thermosetting polymer.  
     
     
         8 . A process according to  claim 5  or  6 , wherein the thermosetting polymer component is initially uncured and forms part of a thermosetting polymer composite.  
     
     
         9 . A process according to  claim 8 , wherein the thermoplastic polymer and the uncured thermosetting polymer part of the thermosetting polymer composite are able to, when heated, at least partly interpenetrate before the thermosetting polymer cures, thereby bonding the thermoplastic polymer to the thermosetting polymer composite.  
     
     
         10 . A process according to any proceeding claim, wherein the thermoplastic polymer is a thermoplastic polymer component or a component with a compatible thermoplastic polymer surface.  
     
     
         11 . A process according to any proceeding claim, wherein the thermoplastic polymer is one of either pure polyvinylidene fluoride (PVDF), or a thermoplastic polymer containing PVDF in combination with other polymers and/or additives.  
     
     
         12 . A process according to any preceding claim, wherein the thermoplastic polymer contains a small amount a lightweight fabric scrim.  
     
     
         13 . A process according to any one of  claims 1  to  11 , wherein the thermoplastic polymer contains material allowing electrical conductivity or localised heating, such as ferromagnetic particles or other electrically conductive material.  
     
     
         14 . A process according to any preceding claim, wherein the thermoplastic polymer is in the form of a film or powder, or is coated directly onto the surface of a mould or tool.  
     
     
         15 . A process according to any preceding claim, wherein the thermosetting polymer is a resin/hardener mixture cured at an elevated temperature.  
     
     
         16 . A process according to any preceding claim, wherein the thermosetting polymer is an epoxy or a bismaleimide.  
     
     
         17 . A cured thermosetting polymer or thermosetting polymer composite component with a thermoplastic surface made in accordance with any preceding claim.  
     
     
         18 . A process for welding a thermosetting polymer or thermosetting polymer composite component with a thermoplastic surface formed in accordance with the process defined in any one of  claims 1  to  16 , to a second component having a thermoplastic surface, the process including: 
 locating and holding the thermoplastic surface of the thermosetting polymer component or thermosetting polymer composite in intimate contact with the thermoplastic surface of the second component;  
 heating the respective thermoplastic surfaces to a temperature above the melting temperature of the thermoplastics for a time such that the thermoplastic surfaces become molten and welding of the adjacent thermoplastic surfaces occurs; and  
 cooling the molten thermoplastic to produce a strong bond between the thermosetting or thermosetting composite components and the second component.  
 
     
     
         19 . A process according to  claim 18 , wherein the second component is a thermosetting polymer or thermosetting polymer composite component having a thermoplastic surface.  
     
     
         20 . A process according to  claim 19 , wherein the second component is formed in accordance with any one of  claims 1  to  16 .  
     
     
         21 . A process according to  claim 18 , wherein the second component is a thermoplastic polymer or thermoplastic polymer composite, or any other component having a suitable thermoplastic surface.  
     
     
         22 . A process according to any one of  claims 18  to  21 , wherein the flow of the molten thermoplastic surfaces is increased by raising the temperature and/or applying more pressure to the two components during heating, or allowing additional process time.  
     
     
         23 . A process according to any one of  claims 18  to  22 , further including adding further layers of semi-crystalline or crystalline thermoplastic material between the thermoplastic surfaces as required to fill gaps or provide high thermoplastic polymer flow.  
     
     
         24 . A process according to  claim 23 , wherein the step of heating also includes heating the additional thermoplastics material to a temperature above the melting temperature of the thermoplastic for a time such that the thermoplastic layers become molten and fuse together.  
     
     
         25 . A process according to any one of  claims 18  to  24 , wherein welding takes place at a temperature below the glass transition temperature of the cured thermosetting polymer or thermosetting polymer composite component.  
     
     
         26 . A thermosetting polymer or thermosetting polymer composite component having a thermoplastic surface formed in accordance with the process defined in any one of  claims 1  to  16  welded to a second component having a thermoplastic surface in accordance with the process defined in any one of  claims 18  to  25 .