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What is Polyurethane Adhesive?
Polyurethane or PU is a polymer distinguished by repeating units of urethane group throughout its structure:
Polyurethane adhesive mainly contains urethane linkages and in addition it may have aliphatic and aromatic hydrocarbons, esters, ethers, amides, urea, and allophanate groups. The addition reaction of diisocyanates or polyisocyanates with polyols through a step-growth polymerization mechanism produces polyurethane, shown below. The functional monomers mentioned earlier can define whether the polyurethane is classified as thermoplastic or thermoset.
Moisture Cured Pressure Sensitive Polyurethane
Urethane polymer resins with unreacted isocyanate groups can react with atmospheric moisture in a two-step process to continue curing.
First, water reacts with some of the free isocyanate groups, the major product is an amine and producing carbon dioxide as a by-product; then the amine further reacts with the remaining isocyanate groups forming urea linkages and fully cured polyurethane urea.
Moisture-curing polyurethanes can penetrate pores and tight spaces where moisture is usually present to form strong chemical bonds.
Morchem Polyurethane Adhesives
Morchem Specialty Adhesives is a company that produces produce polyurethanes. The company specializes in polyurethane technology, particularly in lamination adhesives and coatings. Morchem provides research and development and technical support to ensure the quality of their products. Morchem supplies to markets including flexible packaging, textile lamination, graphic arts, synthetic leather, and printing inks.
3 Recommended Polyurethane Adhesives
Mahachem Inc. (Philippines) just recently acquire the partnership to promote PU adhesive. Morchem recommended three polyurethane adhesives for textile application: Morchem RH 801-3 BS, Newbond NB 9400 and Newbond NB 9405.
Newbond NB 9400 and NB9405 are both 1-component solvent based, moisture curing pressure sensitive polyurethane adhesives. Both can be applied for the joint substrates such as: textiles, leather, clothes with reverse PVC, aluminum paper laminates, plastic and others, in combination with isolating materials like expanded rigid foams (PU, PS) flexible foams, etc. It can also be used in several industrial applications, obtaining a high level of performance.
- Newbond 9405 is designed to minimize the yellowing effect; it can also crosslink to get strong joints, with high flexibility and thermal resistance.
- Newbond 9400 is suitable for laminating plasticized PVC and gives high thermal resistance. The complex bonded materials for both grades can be used in the textile, wood and furniture industry and the automotive industries.
The Morchem RH 801-3 BS is a reactive polyurethane hot-melt adhesive specially indicated for textile lamination. It has a low viscosity that allows low application temperature process. It is specially designed to obtain high cure conversion. It has excellent resistance to dry cleaning and washing resistance at high temperature. It is suitable for standard laminates, woven and non-woven fabrics, foams, polyester and PU films and membranes also PVC.
All three grades are being promoted in the Philippines. Target customers are textile manufacturers/converter and foam manufacturers. Morchem is arranging the sample to be sent after the ECQ in PH. The target application is fabric to fabric and fabric to foam adhesive.
Written by Jasmin from Maha Chem Philippines