• Corrosion Science and Technology
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• v.7 no.6
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• pp.370-374
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• 2008

In this study, we evaluated anti-corrosion properties of both commercial unleaded and lead epoxy primer for automotive substrate before applying to actual painting lines by salt spray test, and cyclic corrosion test, potentiodynamic test and electrochemical impedance spectroscopy. The difference in the corrosion resistance between automotive epoxy primers contained $Bi(OH)_{3}$ and leaded one was investigated. And it was also discussed the effect of zinc phosphate pretreatment to the epoxy primers. The specimen coated epoxy primer contained $Bi(OH)_{3}$ showed 0.5 V higher corrosion potential than that of bare steel. The result of salt spray test did not indicate remarkable difference of corrosion resistance in all specimens above $10{\mu}m$ thickness up to 1200 hours. In the cyclic corrosion test, epoxy primers contained $Bi(OH)_{3}$ on phosphated substrate performed good corrosion properties until 800 hours. The epoxy primer contained $Bi(OH)_{3}$ performed the equivalent corrosion resistance as leaded coating on phosphated steel, but slightly inferior to that of leaded on bare steel. These results show that the pre-treatment of zinc phosphate is effective as well as pigment changing in performing anti-corrosion properties in automotive bodies.

• Elastomers and Composites
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• v.35 no.2
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• pp.89-97
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• 2000

Waterborne epoxy resins have been developed in order to meet environmental regulations for reduction of the emission of organic solvents from coating industry As each generation has filled a performance gap in the previous technology, new waterborne epoxy resin has developed. Initially, waterborne epoxy resins were used primarily on masonry, but the subsequent generations have found utility for the protection of metallic substrates as well. Indeed, the third generation systems have been formulated to produce the high performance industrial maintenance primers which possess the desirable combination of good corrosion resistance and low volatile organic compound levels. This paper outlines the important guidelines for formulating waterborne epoxy primers from waterborne epoxy resin that has recently developed in our company. The importance of using the appropriate resin-curing agent system at the optimized epoxy to amine ratio is stressed.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1160-1169
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• 1999

In this study, the silane primers were introduced to improve the interface adhesion between copper and epoxy. Especially, the polymer types obtained by solution and emulsifier-free emulsion polymerization of vinyltriethoxysilane and the low molecular weight types of 3-aminopropyltriethoxysilane(3-APTES) and 3-glycidoxypropyltrimethoxysilane(3-GPTMS) were used to improve the adhesion strength between epoxy and copper. Also, the surface of copper was treated by 1,1,1-trichloroethane. According to the results, the interfacial adhesion strength of copper-epoxy increased about 2~5 times with the introduction of silane primer. Also, the optimum treatment time of copper surface was about 10 minutes. Additionally, the adhesion strength as a function of concentration of low molecular weight silane was maximum at about 0.5 vol.% for 3-APTES and about 0.2 vol% for 3-GPTMS.

• BMB Reports
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• v.40 no.4
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• pp.511-516
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• 2007

A glutathione S-transferase (GST) related to the phi (F) class of enzymes only found in plants has been cloned from the Oryza sativa. The GST cDNA was cloned by PCR using oligonucleotide primers based on the OsGSTF5 (GenBank Accession No. $\underline{AF309382}$) sequences. The cDNA was composed of a 669-bp open reading frame encoding for 223 amino acids. The deduced peptide of this gene shared on overall identity of 75% with other known phi class GST sequences. On the other hands, the OsGSTF5 sequence showed only 34% identity with the sequence of the OsGSTF3 cloned by our previous study (Cho et al., 2005). This gene was expressed in Escherichia coli with the pET vector system and the gene product was purified to homogeneity by GSH-Sepharose affinity column chromatography. The expressed OsGSTF5 formed a homo-dimer composed of 28 kDa subunit and its pI value was approximately 7.8. The expressed OsGSTF5 displayed glutathione conjugation activity toward 1-chloro-2,4-dinitrobenzene and 1,2-epoxy-3-(p-nitrophenoxy)propane and glutathione peroxidase activity toward cumene hydroperoxide. The OsGSTF5 also had high activities towards the herbicides alachlor, atrazine and metolachlor. The OsGSTF5 was highly sensitive to inhibition by S-hexylGSH, benastatin A and hematin. We propose from these results that the expressed OsGSTF5 is a phi class GST and appears to play a role in the conjugation of herbicide and GPOX activity.