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Test on antibacterial characteristic

Antibacterial characteristic of lacquer Lacquer is mainly used as a coating material. Ever since the old times, it is said that the New Year dishes do not go bad if preserved in lacquer coated layered boxes and that bugs do not eat in and make holes if the cloths are put in lacquer coated drawers. It has been considered that lacquer has function preserving characteristic in addition to its original purpose as a coating material which is to protect and decorate the base material. However, the actual antibacterial and bug-proof characteristics of lacquer were not clearly understood. Focusing on the fact that the structure of urushiol is similar to that of phenolic antibacterial agent, the antibacterial characteristic of lacquer was tested. Further, the regular states of lacquer (liquid, film, mass) limit lacquer from being combined with other materials and therefore, powderization of lacquer is being considered.
Outline of experiment

Samples
Lacquer collected in Japan 1
Lacquer collected in China (Chengkou, Maopo, Bijie) 3
Lacquer collected in Vietnam 1
Total of 5
Antibacterial test of lacquer coating film
Test bacteria: Staphylococcus aureus
Test method: According to “Self-set standard on silver-based inorganic antimicrobial agent, methods of antibacterial test, antibacterial spectrum and film adhesion” by the silver-based inorganic antimicrobial agent research association.
GC-MS analysis
GC-MS analysis was carried out on the composition of monomer component in acetone soluble in lacquer liquid.
Device: GC-MS (HP 5972)
Column: DB-1
Manufacturing of powder that contains lacquer component
Powder containing lacquer component is manufactured by saturating porous powder with urushiol and then heating and hardening the powder.
Result and observation
Results of antibacterial test performed on coating film of lacquer with respect to staphylococcus aureus are shown in table 1. In the coating films of lacquer other than the coating film of lacquer collected in Vietnam, the count of viable bacteria decreased after 24 hours and the antibacterial rate was 100%. Significant antibacterial effect was observed.
Achievement, application and practical use
・It was observed that the coating film of lacquer has antibacterial effect to staphylococcus.
・Powderization of lacquer made it easy to combine lacquer with other materials.
Table 1 Antibacterial effect of coating film of lacquer to staphylococcus aureus
sample count of viable bacteria decrease in count of bacteria
at the time of inoculation after 24 hours
Japanese lacquer 4.3×104 <1.0×102 100
Chengkou lacquer <1.0×102 100
Maopo lacquer <1.0×102 100
Bijie lacquer <1.0×102 100
Vietnam lacquer <1.0×104
Table 2 Antibacterial effect of powder containing lacquer component to Staphylococcus aureus
sample count of viable bacteria decrease in count of bacteria
at the time of inoculation after 24 hours
reference powder <1.8×105 1.3×105 28
powder containing lacquer component <1.0×102 100
blank test 1.7×105 6
FIG. 1 Structural difference in alkenyl catechol according to where the lacquer was collected