Isocyanate-functionalized latexes: Film formation and tensile properties

Mohammed, S.; Daniels, Eric S.; Sperling, L. H.; Klein, A.; El‐Aasser, M. S.

doi:10.1002/(sici)1097-4628(19971205)66:10<1869::aid-app4>3.0.co;2-l

Cited by 33 publications

(23 citation statements)

References 5 publications

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“…They concluded that the NCO groups were evenly distributed throughout the particles under starved, semi‐batch conditions. The tensile properties of films prepared from those latexes gave a clear indication that TMI was contributing to crosslinking . Although they used a different surfactant (sodium dihexyl sulfosuccinate, MA‐80), a lower BA/MMA ratio (≈60/40; wt./wt.)…”

Section: Resultsmentioning

confidence: 99%

“…Mohammed et al reported that higher concentrations of NCO groups at particles' surface had a negative effect on the shelf storage stability of TMI latexes . The proximity of those groups to water made them more susceptible to hydrolysis, resulting in the loss of colloidal stability.…”

Section: Resultsmentioning

confidence: 99%

“…After this time, excess toluene was removed with a pipette and the weights of the swollen samples were registered. For the calculation of M c , the molecular weight between adjacent crosslink points, the method of Mohammed et al was followed. They applied the following equations based on the Flory–Rehner equilibrium swelling theory:

M_{normalc} = \frac{- V_{1} ρ_{normalp} [v_{2}^{1 / 3} - v_{2} / 2]}{ln (1 - v_{2}) + v_{2} + χ v_{2}^{2}}

v_{2} = \frac{W_{normalo}}{ρ_{normals} V_{normals}}

V_{normals} = \frac{W_{o}}{{normalρ}_{p}} + \frac{W_{normals} - W_{normalo}}{{normalρ}_{normals}}

χ = {normalβ}_{1} + V_{1} {(δ_{s} - δ_{p})}^{2} / R T

where W o and W s are the weights of the dried and swollen samples, respectively; ρ p is the BA/MMA (95/5, wt./wt.)…”

Section: Methodsmentioning

confidence: 99%

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Synthesis of Self‐Crosslinkable Water‐Borne Pressure Sensitive Adhesives

Treviño

Dubé

2013

Macro Reaction Engineering

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Self‐crosslinkable acrylic pressure‐sensitive adhesives (PSAs) functionalized with 3‐isopropenyl‐α,α‐dimethylbenzyl isocyanate (TMI) are prepared by starved, seeded semi‐batch emulsion polymerization. n‐Dodecanethiol is used as a chain transfer agent (CTA) and EF‐800 as an anionic surfactant. A three‐level factorial design (32) is performed by varying the TMI and CTA concentrations. Increasing the TMI decreases the rate of polymerization. Nonetheless, high monomer conversions and zero coagulum are observed at the end of all reactions. The latexes are used to prepare PSA films for the evaluation of tack, peel strength, and shear strength. Crosslinking reactions caused by the isocyanate groups of TMI lead to films with very high gel content, even in cases where the CTA concentration is high. As a result, shear strength is greatly improved. The same films preserve sufficient tack but display low peel strength. Empirical models of the tack and peel strength data indicate that TMI has a significant effect on these properties.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

M_{normalc} = \frac{- V_{1} ρ_{normalp} [v_{2}^{1 / 3} - v_{2} / 2]}{ln (1 - v_{2}) + v_{2} + χ v_{2}^{2}}

v_{2} = \frac{W_{normalo}}{ρ_{normals} V_{normals}}

V_{normals} = \frac{W_{o}}{{normalρ}_{p}} + \frac{W_{normals} - W_{normalo}}{{normalρ}_{normals}}

χ = {normalβ}_{1} + V_{1} {(δ_{s} - δ_{p})}^{2} / R T

where W o and W s are the weights of the dried and swollen samples, respectively; ρ p is the BA/MMA (95/5, wt./wt.)…”

Section: Methodsmentioning

confidence: 99%

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Synthesis of Self‐Crosslinkable Water‐Borne Pressure Sensitive Adhesives

Treviño

Dubé

2013

Macro Reaction Engineering

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“…Crosslinking contains one-component and two-component crosslinking. The common crosslinkers for two-component crosslinking mainly include carbodiimide [13,14], polyaziridine [15,16], and isocyanate [17][18][19]. One of the most important and pragmatic one-component crosslinking is the internal crosslinking, which implies the incorporation of polyfunctional monomers.…”

Section: Introductionmentioning

confidence: 99%

Effects of crosslinking on adhesion behavior of waterborne polyurethane ink binder

Liu

Xia

et al. 2015

Progress in Organic Coatings

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“…This is assumed to be due to a catalytic effect on NCO hydrolysis by COOH groups in MAA repeat units rather than to direct reaction between NCO and COOH groups because COOH groups are lower in the hierarchy of reactivity towards NCO groups compared to water. [27] When acetic acid (2 wt% based on total monomer in the formulation) was added to the B20-NA as-prepared latex (which did not contain MAA) immediately before casting the latex (this mixture being coded B20-NA-AA), the rate of NCO loss increased only by a factor of approximately two. Thus the rate of loss of NCO remained much lower than for the latexes in which MAA was incorporated.…”

Section: Studies Of Tmi Part I 1057mentioning

confidence: 99%

Studies of Dimethyl Meta‐Isopropenylbenzyl Isocyanate (TMI) for Preparation of Ambient Cross‐linkable Latexes—Stability of NCO Groups in Latex Form

Lovell

Yoon

2005

Journal of Macromolecular Science, Part B

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Single-pack, ambient cross-linkable acrylic latexes containing dimethyl metaisopropenylbenzyl isocyanate (TMI) repeat units were prepared by batch and semicontinuous emulsion polymerization processes at 408C using methyl methacrylate (MMA) and n-butyl acrylate (BA) as the principal comonomers. The semicontinuous processes were used to prepare structured latexes in which the locus of functional groups within the particles was controlled. In some polymerizations, methacrylic acid (MAA) was incorporated at similar levels to TMI (2 and 5 wt%). An FT-IR method was established for monitoring loss of isocyanate (NCO) groups during latex storage and was shown to give reliable values of rate coefficients. The results showed that NCO functionality was lost gradually over a period of 1-2 weeks depending on latex parameters. Inclusion of MAA repeat units increased the rate of loss of NCO groups by an order of magnitude when the TMI and MAA were uniformly incorporated. The rate also increased significantly on changing latex pH from acidic (pH 1 -4) to basic (pH 9) using NaOH. Particle morphology and functional group location also were important. Loss of NCO groups was fast for core-shell latexes in which the NCO groups were incorporated only in the shell (with more direct access to water from the continuous phase), but much slower when a core containing the TMI and MAA repeat units was protected from the continuous phase by an unreactive poly(MMA/BA) shell layer. The observations show that TMI-containing latexes have a relatively short shelf-life and emphasize the importance of casting films soon after latex preparation for optimum cross-linking during film formation.

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Isocyanate-functionalized latexes: Film formation and tensile properties

Cited by 33 publications

References 5 publications

Synthesis of Self‐Crosslinkable Water‐Borne Pressure Sensitive Adhesives

Synthesis of Self‐Crosslinkable Water‐Borne Pressure Sensitive Adhesives

Effects of crosslinking on adhesion behavior of waterborne polyurethane ink binder

Studies of Dimethyl Meta‐Isopropenylbenzyl Isocyanate (TMI) for Preparation of Ambient Cross‐linkable Latexes—Stability of NCO Groups in Latex Form

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