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Predecessor
Volume 74, Issue 11
Displaying 1-7 of 7 articles from this issue
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Chikara KAWAMURA2001 Volume 74 Issue 11 Pages 538-545
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSIn polyesters synthesized from polyhydric alcohols with three hydroxyl groups or more, molecular weight distributions, branching, and end group structures depend on the amount and the kind of polyhydric alcohols. Therefore, it is necessary for us to investigate reactivity of polyhydric alcohols on the polycondensation and branching structures formed from the polyhydric alcohols in the polyesters. In order to determine reactivity of trimethylolpropane (TMP), pentaerythritol (PE), and glycerol (G) on the polycondensations, we analyzed processes quantitatively during polycondensations of adipic acid (AD) /1, 6-hexanediol (1, 6-HD) /TMP, PE, or G system by 13C NMR spectroscopy. For reactivity of the polyhydric alcohols with AD on esterifications (polycondensations), the following results were obtained. The reactivities of hydroxyl groups of the polyhydric alcohols increased in the following order : (low) G<PE<TMP<1, 6-HD (high). For TMP, reactivity of unreacted, monoesterified, and diesterified TMPs are similar. Similarly, for PE, reactivity of unreacted, monoesterified, diesterified, and triesterified PEs are similar. But, for G, reactivity of primary alcohol in G is about twice higher than that of secondary alcohol in G.View full abstractDownload PDF (1033K) -
Effects of Flow Behavior during Baking and Particle Size of Powder Clearcoats on Film UnevennessKazuyuki TACHI, Yoshiko KOBAYASHI2001 Volume 74 Issue 11 Pages 546-550
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSEffects of the flow behavior during baking and the particle size of powder clearcoats on the unevenness of automotive powder clearcoats over waterborne basecoats have been studied using eight powder clearcoats. The powder clearcoats of particle sizes of 10 and 30μm were formulated with five glycidyl functional acrylic resins and dodecanedioic acid as a hardener. The acrylic resins were of molecular weights (Mn) of 2000, 3000, and 4500 and glass transition temperatures (Tg) of 55 and 68°C. The powder clearcoats were applied to undercoated panels on which a waterborne basecoat was sprayed previously, and orange peel, that is the film unevenness with about 1-5mm wavelength was ranked by two human inspectors. The flow behavior was measured at an angular frequency of 6.28rad/s with an oscillating rheometer.
As the magnitude (η*) of complex viscosity of the acrylic resin of Mn=4500 and Tg=68°C was equal to the steady viscosity at a shear rate of 10-1/s which is known for liquid coatings to dominate leveling, the flow behavior of powder clearcoats during baking was quantified in terms of ∫ (1/η*) dt.
The film unevenness was reduced with decrease in the particle size of powder clearcoats and with increase in ∫ (1/η*) dt. This suggests that the mechanism of film unevenness formation for powder coatings is the same as that for liquid coatings, except that the origin of unevenness by the coalescence of powder particles and leveling occur only during baking.View full abstractDownload PDF (767K) -
Misao HORIGOME, Makoto YADA, Jun-ichiro KOIKE2001 Volume 74 Issue 11 Pages 551-557
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSViscoelastic properties of water base resins and coatings were examined and the origin of their viscoelasticity was discussed. Values of zero-shear viscosity of water base coatings were determined from their dynamic viscosity η' in low frequency region. A clear relationship between the zero-shear viscosity and coating appearance was found. Maximum relaxation time τ1 and its intensity G1 were calculated from viscoelastic properties of water base coatings for the estimation of the viscoelastic mechanism of zero-shear viscosity. The maximum relaxation time τ1 showed a big change with the change in zero-shear viscosity, while the G1 changed a little. The same investigation was carried out for water base resins that included no additives for clarification of the relationship between zero-shear viscosity and the maximum relaxation time τ1. The zero-shear viscosity of water base resins increased in proportion to the maximum relaxation time τ1. From these results, it is deduced that the maximum relaxation time τ1 is the most important parameter that controls the viscoelasitic properties of water base resins and coatings.View full abstractDownload PDF (866K) -
Yutaka SAWADA2001 Volume 74 Issue 11 Pages 558-562
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
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Tomokazu YOSHIMURA, Kunio ESUMI2001 Volume 74 Issue 11 Pages 563-568
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
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Sadahito AOSHIMA, Tomohide YOSHIDA2001 Volume 74 Issue 11 Pages 569-575
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
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Yutaka IKEYAMA2001 Volume 74 Issue 11 Pages 576-583
Published: November 20, 2001
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDownload PDF (1206K)
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