Most waterborne polyurethane is thermoplastic polyurethane, which can be bonded using thermal melting adhesive methods. In this case, it is necessary to master the melting viscosity characteristics of polyurethane. Generally, a melting viscosity of around 104 Pa·s is a suitable temperature for thermal melting bonding.
5. Other
(1) Velvet Processing: In velvet processing, the adhesive must have high adhesion to PVC plastic substrates or fabrics. Velvet fabric requires a formed layer with resistance to both dry and wet washing, as well as adaptability to secondary processing. Electrostatic velvet processing poses a fire hazard, necessitating the use of water-based adhesives. Water-based polyurethane has excellent flexibility, soft adhesive layers, and can be used as a velvet adhesive. The performance of water-based polyurethane with internal cross-linking or water-based polyurethane adhesives with added cross-linking agents exceeds that of ester adhesives. As a velvet adhesive, it must be thickenened.
For example, an anionic polyurethane made from polyether diol, DMPA, polyester plasticizers, a small amount of trihydroxyl cross-linking agent, antioxidant, and triethylamine is thickened to 48 Pa·s with a polyacrylic thickener. It is刮coated on a twill cotton fabric, with a wet adhesive layer thickness of 0.25mm, and 1mm-long artificial silk is sprinkled within 15-30 seconds. The nap is定向by a beater, dried for 5 minutes at 150-155°C, and the unadhered fibers are blown away to obtain a velvet product with a soft fabric feel. After dry-wet abrasion testing, the performance evaluation is Grade A.
With the continuous enhancement of research and development investment, the company's products have gained increasing popularity in the market, propelling the company onto a fast track of development." Yao Dusheng said, "Currently, the company has hired technical experts from countries like Japan and South Korea to focus on product development. Our R&D team alone boasts over 80 members. It's due to our bold investment in R&D that the company's influence within the industry has grown stronger. Currently, products such as solvent-free resins, waterborne polyurethane resins, waterborne surface agents, and environmentally friendly carbon black, all produced by our company, are at the forefront of the industry and are highly favored by customers both domestically and internationally.
Indicators when a condensate is treated as a particle, besides the condensate diameter, include DBP absorption and cDBP. cDBP also affects opacity and dispersibility; the lower the cDBP, the greater the opacity, and the smaller the dispersibility in waterborne polyurethane curing agents.
Generally, methods to reduce the particle size of agglomerates involve adding alkali metal salts or their solutions to the raw oil, or introducing alkali metal salts or their solutions into the combustion or reaction zone.
As an indicator of the narrowness of the particle size distribution of aggregates, waterborne polyurethane thickener has a frequency-based Stokes equivalent diameter D1/2 and a frequency-based Stokes equivalent diameter Dmod ratio D1/2/Dmod, as measured by the centrifugal sedimentation method. Examples indicate that controlling this value within a certain range can impart improved properties to rubber blended with the carbon black.
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