Latent reactive adhesive film

Abstract

The invention relates to an adhesive film which comprises a layer of an adhesive that comprises one or more polymers and at least one peroxide, characterized in that the adhesive comprises at last 50% by weight of thermoplastic polymers that do not have C═C multiple bonds, in that at least one peroxide has the general structural formula R—O—O—R′, wherein R and R′ each represent organyl groups or together represent a cyclic organyl group, and in that the peroxide in solution has a 1-minute half-life temperature of less than 200° C. In a preferred embodiment, the thermoplastic polymer is a polyurethane and the peroxide is a dicumyl peroxide.

What is claimed is: 
     
         1 . A latently reactive adhesive film, comprising:
 a layer of an adhesive, the adhesive comprising one or more polymers and at least one peroxide,   wherein the one or more polymers comprises at least 50% by weight of thermoplastic polymers having no C═C multiple bonds,   wherein the at least one peroxide has the general structural formula R—O—O—R′ where R and R′ each represent organyl groups or collectively represent a cyclic organyl group,   further wherein the at least one peroxide in solution has a 1 minute half-life temperature of less than 200° C., and   further wherein the at least one peroxide exhibits a half-life at 80° C. of at least 13.5 hours.   
     
     
         2 . The latently reactive adhesive film of  claim 1 , wherein
 the at least one peroxide is dicumyl peroxide.   
     
     
         3 . The latently reactive adhesive film of  claim 1 , wherein
 an amount of the at least one peroxide in the adhesive is chosen within the range from 0.1% to 10% by weight.   
     
     
         4 . The latently reactive adhesive film of  claim 1 , wherein
 at least one of the thermoplastic polymers is a polyurethane.   
     
     
         5 . The latently reactive adhesive film of  claim 1 , wherein
 at least one of the thermoplastic polymers is semicrystalline.   
     
     
         6 . The latently reactive adhesive film of  claim 1 , wherein
 the thermoplastic polymers have a maximum softening temperature of not more than 25° C.   
     
     
         7 . The latently reactive adhesive film of  claim 1 , wherein
 the one or more polymers have a maximum glass transition temperature of not more than −25° C., as determined by dynamic differential calorimetry (DSC).   
     
     
         8 . The latently reactive adhesive film of  claim 1 , wherein
 the latently reactive adhesive film is curable by thermal activation.   
     
     
         9 . The latently reactive adhesive film of  claim 1 , wherein
 at least one of the thermoplastic polymers is a thermoplastic elastomer.   
     
     
         10 . The latently reactive adhesive film of  claim 1  further comprising:
 at least one adhesion promoter. 
 
     
     
         11 . The latently reactive adhesive film of  claim 10 ,
 wherein the at least one adhesion promoter is at least one silane functionalized by one or more alkoxy groups.   
     
     
         12 . The latently reactive adhesive film of  claim 11 , wherein
 the one or more alkoxy groups comprises methoxy and/or ethoxy groups.   
     
     
         13 . The latently reactive adhesive film of  claim 1 , wherein
 an adhesive strength of the latently reactive adhesive film, as disposed on a substrate surface, after curing, and after storage at 23° C., 50% relative humidity (RH) for eighteen weeks, is at least 90% of an adhesive strength of the latently reactive adhesive film, as disposed on a substrate surface, after curing, and after storage for not more than one day at 23° C., 50% RH.   
     
     
         14 . The latently reactive adhesive film of  claim 1 , wherein
 an adhesive strength of the latently reactive adhesive film, as disposed on a substrate surface, after curing, and after storage at 40° C. for eighteen weeks in a drying cabinet under standard climatic conditions (23° C./50% relative humidity (RH)), is at least 90% of an adhesive strength of the latently reactive adhesive film, as disposed on a substrate surface, after curing, and after storage for not more than one day at 23° C., 50% RH.   
     
     
         15 . The latently reactive adhesive film of  claim 1 , wherein
 a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as having a thickness of 100 pm and stored beforehand at 23° C., 50% relative humidity (RH) for six weeks, is at least 90% of a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as also having a thickness of 100 pm and stored for not longer than one day beforehand,   each of the adhesive bonds has been established by a pressurized bonding of a polycarbonate disk with a frame made of anodized aluminum by means of a layer of the latently reactive adhesive film,   the pressurized bonding is effected at a temperature of 190° C. and a pressure of 10 bar for 10 s with an effective bond area of 282 mm 2 , and   the force is measured at 23° C. and 50% RH.   
     
     
         16 . The latently reactive adhesive film of  claim 1 , wherein
 a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as having a thickness of 100 pm and stored beforehand at 23° C., 50% relative humidity (RH) for eighteen weeks, then stored at 85° C. and 85% RH for 72 h and reconditioned at 23° C., 50% RH for 24 h, is at least 50% of a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as also having a thickness of 100 pm and stored for not longer than one day beforehand,   each of the adhesive bonds has been established by a pressurized bonding of a polycarbonate disk with a frame made of anodized aluminum by means of a layer of the adhesive film,   the pressurized bonding is effected at a temperature of 190° C. and a pressure of 10 bar for 10 s with an effective bond area of 282 mm 2 , and   the force is measured at 23° C. and 50% RH.   
     
     
         17 . The latently reactive adhesive film of  claim 1 , wherein
 a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as having a thickness of 100 pm and stored beforehand at 40° C. in a drying cabinet under standard climatic conditions (23° C./50% RH) for eighteen weeks and then stored at 85° C. and 85% RH for 72 h and reconditioned at 23° C., 50% RH for 24 h, is at least 50% of a force that acts perpendicularly and completely parts an adhesive bond established with the latently reactive adhesive film, as also having a thickness of 100 pm and stored for not longer than one day beforehand,   each of the adhesive bonds has been established by a pressurized bonding of a polycarbonate disk with a frame made of anodized aluminum by means of a layer of the latently reactive adhesive film,   the pressurized bonding is effected at a temperature of 190° C. and a pressure of 10 bar for 10 s with an effective bond area of 282 mm 2 , and   the force is measured at 23° C. and 50% RH.   
     
     
         18 . The latently reactive adhesive film of  claim 1 , wherein
 the at least one peroxide exhibits a half-life at 80° C. of at least 22.5 hours.   
     
     
         19 . The latently reactive adhesive film of  claim 1 , wherein
 the at least one peroxide exhibits a half-life at 80° C. of at least 69 hours.   
     
     
         20 . The latently reactive adhesive film of  claim 1 , wherein
 the at least one peroxide is a ketone peroxide or a cyclic peroxide.   
     
     
         21 . A one-component latently reactive adhesive film comprising:
 (i) an adhesive composition comprising:
 a polymer component comprising at least 50% by weight of at least one thermoplastic polymer lacking C═C bonds and lacking C≡C bonds; and 
 at least one peroxide having a general structure R—O—O—R′, where R and R′ are organyl groups; and 
   (ii) a reinforcing layer, carrier layer, or liner disposed on one side of the adhesive composition;   wherein, the adhesive composition is storage stable and does not cure or cures over a period of months under standard climatic conditions of 23° C. and 50% relative humidity;   wherein, the adhesive composition is thermally reactive, and upon thermal activation, the adhesive composition melts and a cross-linking reaction involving the at least one thermoplastic polymer occurs; and   wherein, the one side of the adhesive composition is configured to be adhered to a first substrate; and   wherein, the other side of the adhesive composition is configured to be adhered to a second substrate, such that the first substrate and the second substrate are attached to each other and neither the first substrate nor the second substrate are adhesives.   
     
     
         22 . The one-component latently reactive adhesive film of  claim 21  further comprising a second reinforcing layer, carrier layer, or liner disposed on the other side of the adhesive composition. 
     
     
         23 . The one-component latently reactive adhesive film of  claim 21 , wherein
 the adhesive composition further comprises a silane adhesion promotor and a tackifier resin.   
     
     
         24 . The latently reactive adhesive film of  claim 21 , wherein
 the at least one peroxide comprises a ketone peroxide or a cyclic peroxide.   
     
     
         25 . A latently reactive adhesive film comprising:
 an adhesive composition comprising:
 a polymer component comprising at least 50% by weight of at least one thermoplastic polymer lacking C═C bonds and lacking C≡C bonds; and 
 at least one peroxide comprising a ketone peroxide or a cyclic peroxide; 
   wherein, the adhesive composition is storage stable and does not cure or cures over a period of months under standard climatic conditions of 23° C. and 50% relative humidity; and   wherein, the adhesive composition is thermally reactive, and upon thermal activation, the adhesive composition melts and a cross-linking reaction involving the at least one thermoplastic polymer occurs.   
     
     
         26 . The latently reactive adhesive film of  claim 25  further comprising:
 a reinforcing layer, carrier layer, or liner disposed on one side of the adhesive composition; 
 wherein, the one side of the adhesive composition is configured to be adhered to a first substrate; and 
 wherein, the other side of the adhesive composition is configured to be adhered to a second substrate, such that the first substrate and the second substrate are attached to each other and neither the first substrate nor the second substrate are adhesives.