Moisture curable

Neopentyl alcohol is useful for preparation of masked polyol siUcate esters, capable of releasing the polyol under moisture conditions, in moisture-curable one-component Hquid polyurethane compositions (90). 

New raw materials will be the key to unlocking the opportunities above and to creating the possibility for new sets of adhesive properties. On the horizon are new types of moisture curable systems and a variety of novel block copolymers. The future may find entirely new mechanisms or morphologies for strength development on cooling. 

Moisture-curable urethane systems (one-pack) can be considered as two-component systems which use atmospheric moisture as the second component. One-pack urethane coatings can be produced that are similar in physical properties to the two-pack systems for almost all applications. These highly complex systems can have a great deal of flexibility. Claimed advantages are a one-pack system, rapid cure, even at low temperatures, excellent chemical and abrasion resistance and good flexibility. Although these systems have been available for some time in other countries of Europe, they are only recently beginning to be of interest in the UK. 

Example 11. One-Component, Moisture-Cure Polyurethane Sealant. This example is of a low-hardness, high-elongation, moisture-curable polyurethane sealant. The material is based on a low-%NCO prepolymer made from 4,4 -MDI and a low-unsaturation (low-monol-content) Acclaim polyol from Bayer. It is adapted from (a) J. Lear et al., Adhesives Age, February 1999, pp. 18-23 and (b) B. Lawrey, et al., presented at UTECH 2000, The Hague, The Netherlands, March 30, 2000, Crain Communications London, 2000. 

Some of the more interesting and innovative work has occurred in areas combining aspects of more than one chemistry type. For instance, moisture-curable thermoplastic adhesives have received much attention. Hot melt adhesives have been developed that contain active, moisture-curable isocyanate groups. The compositions provide rapid processing on assembly lines because a reasonable bond is formed as soon as the thermoplastic adhesive cools from the melt. However, bond strength and performance improve with time as the composition is slowly crosslinked to a thermoset by reaction of the isocyanates with atmospheric moisture.96,97... 

Fukatsu, S. and Hattori, Y., Moisture Curable Polymer Composition and Process for Production Thereof U.S. Patent No. 5,767,197, 1998. 

Moisture curable n-butyl acrylate oligomers materials containing a dimethox-ymethyl hydrosUane termini were prepared by Ohshiro [2] and the author [3] that had good heat resistance, weatherability, oil resistance, and low staining properties. 

Many commercial polymer matrices can be processed into single-component, moisture-curable systems by means of silane cross-linking (Scheme 1) [3]. 

The attachment of trialkoxysilane functionality to polyolefins (HDPE, LDPE, PP) though grafting of vinylsilanes e.g. 40, 41) or silane functional acrylates e.g. 42) has been widely studied. The principal application of these materials is the preparation of moisture curable crosslinked polyolefins that arc widely used in the cable industry. Silane treatment has also been used for surface modification of polyolefins " and silane grafted polyolefins might also serve as precursors to graft copolymers. 

Uses Silicone for defergenf-resisf. car polishes, vinyl condifioners, and waterproofing coafings Features Moisture curable, exc. adhesion Regulatory DOT nonregulated SARA 311 nonreportable Properties Clear to si. hazy liq. mild amine odor sol. in aliphatic hydrocarbons sp.gr. 0.98 dens. 8.0 Ib/gal vise. 190 cSt b.p. > 500 F flash pt. (PMCC) > 93 C 100% act. 

Features Exc. elec, props. RTV high speed moisture curable low hardness films may be removed mechanically or by solv. means includes UV tracer dye to enable inspection of coating integrity low vise. solv.-... 

Tough, moisture-curable films based on polyisocyanates made from lEM are suggested for use in coatings, leather impregnants and seamless floor coverings (11,12). 

A range of halogen-free low smoke compounds for cable insulation and sheathing are available from AEI Compounds Ltd., in Gravesend, England. These come under the Catapyrric trade name. Some, such as SX545 CM540U ate silane crosslinkable whereas others are moisture curable or entirely thermoplastic. 

Room Temperature Vulcanizable (RTV) Silicones. One-component, moisture-curable, room-temperature vulcanizable (RTV) silicones represent one of the largest-volume and commercially most successful silicone technologies. When exposed to atmospheric moisture, RTV silicones undergo hydrolysis and... 

A moisture-curable urethane resin is simply a urethane prepolymer with free -NCO groups. Typically made from aromatic isocyanates, the free -NCO group of such a resin, when exposed to the environment after application, will react with ambient moisture and produce urea linkages between prepolymer chains, resulting in formation of the cured coating (Figure 2.64). 

Figure 2.64 Schematic representation of curing of moisture-curable urethane system...

Moisture curable Isoprene-co-isobutene polymers United States 4,048,258 1977 Exxon Research... 

PE copolymerized with a silane is available on the market. It is sold as a moisture curable type of PE... 

Most adhesives which crosslink at room temperature are packaged in two containers, mixed just before use. The moisture-curable adhesives and sealants, however, are single-component compositions which have long shelf life as long as they are in closed containers, but react when dispensed and thus exposed to water vapor in the air. Among the growing roster of moisture-curable systems are three types of... 

Table 20. Polyurethane-Based Sealant, Moisture Curable (Single Component. Gun Grade. White).

Cure characteristics of one-component systems categorise adhesives as moisture curable, UV curable, powder blocked isocyanates, etc., and for two-components systems as either polyol-isocyanate reactive curable or polyol-amine reactive curable. 

Some of the advantages of moisture curable CASE polyurethanes are that there are no solvent emissions, and an improvement in properties due to the formation of urea groups. 

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