Blister resistance

Static modulus, extrusion resistance blister resistance... 

One of the first attempts to produce polyurethane was from the reaction of an intermediate polyol of 1,3- and l,4-bis(hydroxyhexafluoroisopropyl)benzene m- and />-12F-diols) by reaction with epichlorohydrin. This polyol was subsequently allowed to react with a commercial triisocyanate, resulting in a tough, cross-linked polyurethane (129,135,139). ASTM and military specification tests on these polyurethanes for weather resistance, corrosion prevention, blister resistance, and ease of cleaning showed them to compare quite favorably with standard resin formulations. 

Resistance to moisture Flexural strength Flexural modulus Tensile strength Postforming laminate only Postformability Blister resistance Melamine-faced chipboard only Resistance to wet heat Surface soundness Composite boards only ... 

This chapter describes ionic cross-linldng of the HASE thickener with zinc oxide or zinc ammonium complexes to improve early blister resistance. Zinc ammonium complexes have been used in ammonia-removable latex floor polishes for decades. Paint formulations containing zinc oxide have benefits but are prone to sporadic viscosity instability, which sometimes cannot be predicted by standard laboratory tests. However, many paint manufacturers have learned how to successfully stabilize these zinc oxide-containing latex paints. 

Zinc Oxide. We found that as little as 5 lb of zinc oxide per 100 gal (1 gal = 3.785 L) of paint was sufiBcient to impart acceptable early blister resistance to the paint when tested in the rain or in the tap water fog box (Table I). Higher zinc oxide levels showed no further blister-resistance improvement in this paint. Blistering in the deionized water fog box was so severe that even the HEC-thickened control had a blister rating of 4D. (The note to Table I explains the rating method used.) However, a noticeable effect occurred at zinc oxide levels of 5 lb/100 gal of paint and higher. The zinc oxide combined with the ammonia in the paint and formed a zinc ammonium complex that may ionically cross-link the carboxyl groups in the HASE thickener and other paint constituents, and thereby reduce the overall water sensitivity of the paint. 

Zinc Ammonium Complexes. The zinc ammonium complexes were tested on a different chalky latex panel than the zinc oxide paints, and the entire series showed less blistering in the same deionized water fog box (Table II). The HEC-thickened control did not blister on this board. The HEUR control showed 7M blisters on this board vs. 2MD (Table I). Addition of the zinc ammonium complexes resulted in much-improved early blister resistance. Blister-resistance effectiveness differed depending on which complex was used. The four zinc ammonium complexes evaluated in the HASE-... 

Table I. Blister Resistance of ZnO-Modified Paints with HASE Thickener ...

Table U. Blister Resistance of HASE-Thickened Paints Modified with Zinc Ammonium Complexes ...

The stoichiometry at effective zinc ammonium complex levels suggests that zinc reacts with more carboxyl groups in the paint (latex, dispersants, etc.) than in the HASE thickener. Even with the most efficient complex, zinc ammonium acetate, more zinc was required to obtain good blister resistance than the stoichiometric equivalent of the carboxyl groups in the HASE thickener (Table II). 

Fog Boxes vs. Rain. Like many other accelerated tests, the fog box blister-resistance test shows trends rather than an exact correlation with the results observed in actual rainfall. When deionized water is used for the spray in the fog box, the test is most stringent, and blister differences can be observed in paints that do not blister when the much less stringent tap water fog is used. The tap water test correlates more closely to what is generally seen on the test fences when paint films no more than a few days old are exposed to rain. 

Ionic cross-linking of the water-sensitive carboxyl groups in the HASE thickeners (and probably other carboxyl groups in the paint) with either low levels of zinc oxide in the mill base or post-added zinc ammonium complexes can be effective in improving the early blister resistance of HASE-thickened latex paints over heavily chalked latex paint surfaces. Of the zinc ammonium complexes evaluated, the zinc ammonium carbonate and bicarbonate ap-... 

The chemical compositions of the gelcoat and backing resins are the most important factors for the provision of blister resistance. Isophthalic gelcoats are generally superior to orthophthalic ones. Isophthalic acid/neopentyl glycol based gelcoats have even better blister resistance than those based on... 

Careful control over the thickness of the gelcoat is very important. Very thin gelcoats are much less effective. Choice of fibre finish is crucial and laminates containing powder bound CSM display lower water absorption and higher blister resistance than those made from emulsion bound CSM. The use of surface tissue immediately behind the gelcoat can significantly reduce the chance of blistering. 

Uses Drying oil for prep, of quality coating vehicles by cold blending (clear exterior finishes, aluminum paints, anticorrosive primers, blister-resist. wood primers, alkyd modification)... 

Uses Dispersant for interior and exterior architectural coatings Features Hydrophobic good water resist., early blister resist., exc. gloss development, color acceptance low VOC Prc retHes Water-wh.-yel. clear liq. dens. 9.2 Ib/gal vise. 500 200 cps pH 8-8.5 anionic 30% solids... 

Chem. Descrip. Ammonium salt of carboxylated polyelectrolyte Uses Pigment dispersant for flat thru gloss latex paints Features High performance exc. early blister resist. exc. wet adhesion capability good color acceptance good gloss development and corrosion resist. 

Uses Coating binder for paper/paperboard, size press, wallpaper applies., esp. mod. gloss level publication grades and matte and dull grades Features Outstanding wet and dry pick resist. exc. blister resist, for web offset grades... 

Polymer architecture plays a crucial role in final properties. Thus, in papers coated with carboxylated styrene-butadiene latexes, blister resistance decreases and dry pick increases... 

An additional evaluation [18] of the extension of rutile Ti02 by different fillers was conduded by assessing blister resistance in two types of liquid, thermosetting polyester resins (namely ortho- and ortho-neopentyl glycol (NPG). The performance of the filler/pigment portion of the cured polyester gel coat was compared after exposure to water at 65 °C for 1150 h (Table 13.12). Untreated kaolin provided better blister resistance than untreated talc or calcium carbonate. Vinylsilane surface-treated kaolin gave the best blister resistance, reducing the size and extent of blisters... 

Blister house n. House-like structure used as an accelerated test for blister resistance of coatings. Under controlled conditions, it attempts to simulate or accelerate bhster-ing, which occurs on buildings. 

Blistering resistance n. The ability of a coating to resist the formation of dome-shaped, liquid- or gas-filled projections in its film resulting from local loss of adhesion and lifting of the film from the underlying surface or coating. 

Great Lakes offers Firemaster BP411, launched in 2004 for the manufacture of electrical connectors, relays and switches. Firemaster CP-44HF is a high-flow polybrominated styrene copolymer for polyesters and high temperature polyamides, while Fire Firemaster PBS 64HW is dibromostyrene-based. This type of FR is said to offer good thermal stability, flow and blister resistance. 

Resistance of scribed line to corrosion after predetermined exposure period loss of adhesion blistering Resistance to corrosion around fastener heads rating per ASTM D 1654... 

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