Process for printing adhesives, adhesive articles and printing equipment

Abstract

The present invention relates to a process for printing specific adhesives onto articles, such as absorbent articles or release paper, using a specific transfer tool and/or a specific adhesive, having a specific peel force, viscosity, elastic loss modulus, elastic modulus, surface energy and loss tangent modulus; the invention also relates to articles comprising the specific adhesives and to specific printing rolls.

1 . A process for transferring from a surface of a transfer tool a sticky material having a peel force of at least 0.1N/cm onto an article, series of articles or web of articles, with reduced stringing, whereby the contact angle of the sticky material and the surface of the tool is more than 60° at the process temperature.  
   
   
       2 . A process for transferring from a surface of a transfer tool a sticky material having a peel force of at least 0.1N/cm onto an article, series of articles, or a web of articles, with reduced stringing, wherein the sticky material has: 
 a) a viscosity η of less than 2500 mPa·s at process temperature; and    b) an elastic loss modulus G′ that increases from 10 to 10,000 Pa in less than 60° C. temperature range.    
   
   
       3 . The process of  claim 2  whereby the sticky material has 
 a) an elastic modulus G′ at 20° C. of less than 100,000 Pa;    b) a loss tangent tan δ (G″/G′) at 20° C. of more than 0.5; and    c) a surface energy as at 20° C. of less than 35 mJ/m 2 .    
   
   
       4 . The process of  claim 1 , wherein the sticky material has: 
 a) a viscosity η of less than 2500 mPa·s at process temperature; and    b) an elastic loss modulus G′ that increases from 10 to 10,000 Pa in less than 60° C. temperature range.    
   
   
       5 . The process of  claim 4  wherein the transfer tool has a surface comprising a coating, wherein said surface has a contact angle with the sticky material of more than 60° at the process temperature, and wherein the coating comprises a polyfluorinated polymer.  
   
   
       6 . The process of  claim 5 , wherein the transfer tool is a printing roll and the sticky material is applied onto said roll, wherein the process is a continuous process whereby the material is applied continuously on said roll and applied continuously on a web of articles, and wherein the process has a speed of at least 20 m/min.  
   
   
       7 . The process of  claim 5  wherein the material is applied in an on-dot amount of at least 10 g/m 2 .  
   
   
       8 . The process of  claim 6 , wherein the process is a gravure printing process, the roll having cavities to receive the sticky material.  
   
   
       9 . The process of  claim 6  wherein the transfer of the material from the roll onto the article, series of articles or web of articles is done by placing the article, series of articles or web of articles on a second roll and bringing this in contact with the roll with the sticky material with a force/length of at least 700N/m.  
   
   
       10 . The process of  claim 9  wherein the web of articles is stretchable and rotates around the second roll such that the exit angle is between 30° and 70°.  
   
   
       11 . The process of  claim 5  wherein the sticky material comprises an adhesive.  
   
   
       12 . The process of  claim 5  wherein the article is an absorbent article or release strip thereof.  
   
   
       13 . The process of  claim 5  wherein the temperature of the transfer tool is from 110° C. to 175° C.  
   
   
       14 . The process of  claim 13  wherein the temperature of the transfer tool is higher than the melting point temperature of the articles, series of articles or web of articles.  
   
   
       15 . A gravure printing roll having a surface coating, wherein the surface coating comprises a polyfluorinated polymer.