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Uniform Cross Linking of Aziridine Polymers with Dimer Acids |
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Written by Renato Rindone
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Monday, 28 September 2009 12:10 |
Uniform Cross Linking of Aziridine Polymers with Dimer Acids 
Polyaziridines, such as Xama-2 and Xama-7 are used in a number of applications such as:
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Adhesives
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Varnishes
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Protective Films
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Pressure Sensitive Adhesives
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Wood Coatings
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Photograph Films
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Printing Inks
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Leather and Textile Coatings
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Plastic Films
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Cross linking of an aziridine with a poly functional carboxylic acid (or carboxylic acid anhydride) can be the desired end product.
Use of Hycat™ catalysts eliminates the problem of homopolymerization as shown in the reaction of pentaerythritol-tris-3-(1-aziridinyl)-propionate (Xama-7) with a dimer acid.
Into a mixing cup were weighed 15.5 grams (100.3 meq) of Xama-7, 27.7 grams (101.6 meq) of Empol 1016 dimer acid and 4.28 grams of Hycat™ 2000/2000S. The mixture was mixed for two minutes with a spatula, and then placed into a Garner wire-stirred gel timer (Model GT-S) at 32 OC. After one minute of stirring the contents of the cup were completely solidified into a uniform, hard rubbery mass. Considerable heat was liberated during this period. As a control, the reaction was also performed without the use of the Hycat™ catalyst. Into an aluminum pan (60 mm diameter) were weighed1.6 grams (10.36 meq) of Xama-7 and 2.7 grams (9.90 meq) of Empol 1016 dimer acid and mixed for 2 minutes with a spatula then allowed to stand at 32 OC overnight. After 15 minutes the composition was tacky which solidified into a semi-tacky mass on standing overnight.
ATTEMPTED HOMOPOLYMERIZATION OF XAMA-7 WITH HYCAT™ CATALYST
To show that Xama-7 does not homopolymerized in the presence of Hycat™ catalysts even at elevated temperature, 6.8 grams of Xama-7 and 0.4 grams of Hycat™ 2000/2000S were placed into an aluminum pan, thoroughly mixed with a spatula then heated to 41 OC for 3.25 hours. The contents of the pan were still quite fluid. After 9 days storage at about 20 OC the contents of the pan remained fluid.
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