Polyurethane Based Pressure Sensitive Adhesive for Tapes

1. Polyurethane Based Pressure Sensitive Adhesive for Tapes By: Dafna Heiman Supervisor: Prof. Hanna Dodiuk Dr. Anna Dotan Industry: Polyurethane Haifa- Arik Katzenstein

2. Introduction • Pressure sensitive adhesives are materials which adhere with only a light finger pressure. • They are commonly known in everyday use as labels or tapes. • Ideal adhesive is one that sticks to its substrate with a touch of the finger and detaches from it easily and without leaving residues.

3. Introduction • Pressure sensitive adhesive (PSA) raw materials: • Natural rubber • Acrylic adhesives -polyacrylic esters – Curing in elevated temperatures. • Styrene block copolymers • Silicones • Despite its great versatility Polyurethane is not commercially found in this field.

4. Objectives • Developing PU based PSA for paper with the following properties: • Single/dual component adhesive • A non drying adhesive • Durable in long periods of time • Suitable for tapes • Will not stain the carrier paper

5. The secret of PSA elasticity + tackifier Controlling Mc Using the soft segments of the PU An additive used to increase tack properties

6. Medical applications formulations Part A: Part B: Hostettler F., and Wachtel P., "Methods of preparing polyurethane adhesives, adhesives produced thereby and medical devices employing the same", US patent no. 6,359,100, 2002.

7. Methodology • Formulation fitted to the existing materials by stoichiometry calculations. • A full reaction between the reactive components is necessary to avoid staining. • Viscosity of the final adhesive is relatively high and needs to be reduced. • The solution for the problem was the use of a solvent (acetone) or excess of diisocyanate in part B.

8. Methodology • components can be changed to achieve the best mechanical results: • Tackifier amount • Solvent amount • diisocyanate amount • Testing the samples mechanical properties and characterization. • Comparing the mechanical properties to commercial adhesives.

9. Experimental • The following materials were used in this project: • Acclaim 3201- poly (oxyalkylene) polymer, a polyether polyol by Bayer. • Tripropylene glycol (TPG) - 97% by Sigma Aldrich. • Dibutyl tin laurate (DBTDL) - an organotin product mainly used as a catalyst in the production of polyurethane. • Desmodur vks 20f- a mixture of diphenylmethane- 4, 4-diisocynate (MDI) with isomers and higher functional homologues (PDMI), by Bayer. • Regalrez 1018- an hydrocarbon Resin with cycloaliphatic structure, it is produced by polymerization and hydrogenation of pure monomer hydrocarbon feedstocks. By Eastman. • Acetone- used as a solvent.

10. Experimental • Sample preparation: • Mixing polyol and TPG in room temp. • Adding diisocyanate and DBTDL. • After 30 min heating to 600 and mixing for 3.5 hr. • Adding part B. • The adhesive is then applied using a rolling pin on to paper and covered in protecting paper.

11. Experimental • Composition of the final formulas:

12. Experimental – Testing methods • 1800 peel test • FTIR- used to determine additives effect on crosslinking rate. • DSC-used to determine Tg and to show the effect of the additives on crosslinking degree.

13. Results and Discussion • The samples containing high amount of acetone did not adhere incomplete layer • Samples containing excess of diisocyanate did not adhere and caused loss in elasticity phase separation and foaming

14. 1800 peel test results • comparison to reference samples is problematic • comparison of different manufactures tapes gives different results

15. FTIR • Increase in tackifier % accelerates crosslinking rate • High % of tackifier are a limit due to distancing of chains

16. FTIR

17. DSC Results

18. Conclusions • Comparison of different tapes of the same manufacture is possible and should give good results. • Tack properties are controlled mainly by the amount of tackifier in the formulation. • Stoichiometry must be complete in order to prevent staining of the paper by oily residue from polyol or glycol excess. • Excess of diisocyanate will cause foaming which results in decrease in tack properties due to phase separation.

19. Conclusions • Reducing viscosity causes an increase in crosslinking rate to a limit. • Higher rate of crosslinking results in less staining of the carrier paper. • Using a solvent to reduce viscosity requires using a solvent recycling system.

20. Recommendation for further work • Test the adhesive properties versus a commercial tape but from the same manufacture. • Investigating the effect of different tackifiers on the tackiness of the adhesive using a roll ball test. • Experiment in large scale production versus laboratory scales. • Viscosity should be measured as function of time using a parallel plate viscometer.

21. References 1. Handbook of thermoset plastics, Sidney H. Goodman (editor), Noyes publications (Park Ridge, New Jersey), 1986, p.183-264. 2. Polyurethane handbook, 2nd addition, Gunter Oertel (editor), Hanser publishers (Munich), 1994, p. 37-46, 595-613. 3. Adhesion and adhesives technology, 2nd edition, Alphonsus V. Pocius (author), Hanser pulishers (Munich), 2002, p. 132-199, 238-268. 4. Adhesive and adhesive tapes, G. Gierenz, and W. Karmann (editors), Wiley-Vch (Weinheim), 2001, p. 3-6, 98-120. 5. Development and Manufacture of Pressure-sensitive Products, I. Bendek (author), Marcel Dekker, inc.1999, p. 1-35. 6. Wengelski T., "Key properties and considerations in selecting paper tape backings", Wausau paper-specialty products, http://www.pstc.org/, 2006. 7. Dokner C., "The chemistry of tackifying resins", Hercules BV, http://www.pstc.org/, 2005. 8. Griswold R.M., Eckberg R., Frye R., "A new family of pressure sensitive adhesives", GE Advanced materials, http://www.pstc.org/, 2006. 9. Creegan R.M., White D.J., "Pressure sensitive adhesive labels and method of making", US patent no. 3,914,484, 1975. 10. Dahl R., "New polyurethane pressure sensitive adhesive products and processes", US patent no. 3,802,988, 1974. 11. Goel A.B., "Flexible, structural polyurethane adhesives with initial pressure sensitive adhesive performance", US patent no. 4,803,257, 1989. 12. Hostettler F., and Wachtel P., "Methods of preparing polyurethane adhesives, adhesives produced thereby and medical devices employing the same", US patent no. 6,359,100, 2002. 13. Miyake J.I, Yamazaki K., Kamatani Y. "One can type pressure sensitive adhesive composition", US patent no. 4,448,947, 1984. 14. Miyake J.I, Yamazaki K., Kamatani Y. "Two package type pressure sensitive adhesive composition prepared from a polyurethane containing a terminal free isocyanate group and an oxadiazine-2,4,6-trione ring", US patent no. 4,471,103, 1984. 15. Moeller, Thomas, Gensch, Ingo, Fischer, Herbert, Huebner, Norbert, Plum, Hermann-Josef, Herlfterkamp, and Bernhard, "Polyurethane adhesive", US patent no. 6,630,050, 2003. 16. Muller H., Szonn B., "Adhesive sheets and webs and process for their manufacture", US patent no. 3,930,102, 1975. 17. Shikinami Y., Hata K., "Pressure sensitive adhesive for transdermal absorption formulations", US patent no. 5,773,490,1998. 18. Winslow E.L., "Pressure sensitive adhesive tape", US patent no. 4,374,883, 1983. • Wong W., "Thermally stable clear polyurethane adhesive tape", US patent no. 6,726,971, 2004. • "Standard test method for peel adhesion of pressure sensitive tape", astm D3330/D3330M-04, 2004.