• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.749-757
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• 2019

Methyltrimethoxysilane (MTMS) and trimethylethoxysilane (TMES) as starting materials were dissolved in various types of solvents, and hydrolysis with water and polycondensation reaction were carried out using various types of catalysts to prepare non-fluorinated water-repellent coating solutions. The coating solutions were spin-coated on cold-rolled steel sheets, and thermally cured to prepare water-repellent coating films. The effect of types of catalysts and solvents on the water repellency of the resulting coating films was investigated during this process. When hydrochloric acid and nitric acid, which are strong acids, were used as catalysts, the solutions showed a white opaque state due to the aggregation of siloxane polymers. On the other hand, when acetic acid, phosphoric acid, and oxalic acid, which are weak acids, were used, they were in a stable and transparent state without precipitation. As a result, the contact angles of the coated films, prepared from hydrochloric acid and nitric acid, were $58^{\circ}$ and $92^{\circ}$, respectively, showing low water repellency. On the other hand, when acetic acid, phosphoric acid, and oxalic acid were used, the contact angles of the coated films were $101^{\circ}$, $103^{\circ}$ and $116^{\circ}$, respectively, showing high water repellency. In addition, when isopropanol and ethanol were used as solvents, phase separation occurred in the solutions due to the aggregation of siloxane polymers. On the other hand, when methanol, ethyl acetate, and methyl ethyl ketone were used as solvents, the solutions were transparent and showed a stable state without sedimentation.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.2
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• pp.204-208
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• 2012

Water repellency which affects infiltration, evaporation, erosion and other water transfer mechanisms through soil has been observed under several natural conditions. Water repellency is thought to be caused by hydrophobic organic compounds, which are present as coatings on soil particles or as an interstitial matter between soil particles. This study was conducted to evaluate the characteristics of the water repellent soil and transport characteristics of trace elements within this soil. Capillary height of the water repellent soil was measured. Batch and column studies were accompanied to identify sorption and transport mechanism of trace elements such as $Cu^{2+}$, $Mn^{2+}$, $Fe^{2+}$, $Zn^{2+}$ and $Mo^{5+}$. Difference of sorption capacity between common and repellent soils was observed depended on the degree of repellency. In the column study, the desorption of trace elements and the spatial concentration distribution as a function of time were evaluated. The capillary height was in the repellency order of 0% > 15% > 40% > 70% > 100%. No water was absorbed in soil indicating >70% repellency. Using trace elements, $Fe^{2+}$ and $Mo^{5+}$ showed higher sorption capacity in the repellent soil than in non-repellent soil. The sorption performance of $Fe^{2+}$ was found to be in the repellency order of 40% > 15% > 0%. Our results found that transfer of $Mo^{5+}$ had similar sorption tendency in soils having 0%, 15% and 40% repellency at the beginning, however, the higher desorption capacity was observed as time passes in the repellent soil compared to in non-repellent soils.

• Textile Coloration and Finishing
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• v.5 no.1
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• pp.1-9
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• 1993

The polymethylhydrosiloxane(PMHS) was synthesized by the co-hydrolysis of methyldichlorophydrosilane and ethyl ether, also polydimethylsiloxane(PDMS) was synthesized by the hydrolysis of dimethyl dichlorosilane and ethyl ether. The silk fabrics were treated with PMHS and PDMS in order to improve the water repellency and the wrinkle recovery. Also the effect of PMHS concentration, PDMS concentration and cure temperature on the physical properties of silk fabrics were studied. The maximum water repellency and maximum wrinkle recovery were obtained from the fabrics treated under the conditions 5%-PMHS and PDMS at 16$0^{\circ}C$, and 3%-PMHD and PDMS at 16$0^{\circ}C$, respectively. The tensile strength, the breaking elongation, the reflection and the bending properties of silk fabrics were not degraded severely by the treatment of PMHS or PDMS.

• Textile Coloration and Finishing
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• v.5 no.2
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• pp.125-133
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• 1993

This study was to investigate the application of foam finishing technology (FFT) for the silicone finishing of cotton fabrics and the tluorochemical finishing of polyester fabrics. The repellency properties, soil resistance properties and selected physical properties were demonstrated and compared the foam finishing with the conventional padding application. Amino-funetional silicone prorided better durability than epoxy-functional silicone and conventional reactive silicone after three launderings. Foam finishing fabrics improved stiffness but showed lower or equivalent water and oil repellency properties, soil resistance properties, tearing strength and abrasion resistance than those of the fabrics treated by conventional padding process. But, it was evident that the foam application of silicone and fluorochemical finishes to the fabrics were feasible.

• Journal of Korean Society for Quality Management
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• v.16 no.1
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• pp.43-48
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• 1988

Most of silicone used for water repellent finish is MHP (methyl hydrodiene polysiloxane), which is formed by hydrolysis and condensation polymerization of MHD (methyl hydrodiene dichlorosilane: Me H Si $Cl_2$). The cross-linking theory explains the water repellent mechanism of MHP. The silicone finish on fiber could improve in handle, softness, abrasion resistance, soil repellency, tear strength and crease resistance, as well as water repellency. According to using method silicone-water repellent finishing agents, could be devided into air dry type and curing type. MHP is the typical curing type of water repellent finishing agent, and this type requires the curing temperature above $150^{\circ}C$ at least. High curing temperature is the very drawback of this curing type. For this reason, there has been global interest in the lowering of its temperature. The objective of this study is to investigate merits of alkali treatment for silicone finishing by ANOVA and LSD (least significant difference).

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.11a
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• pp.207-212
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• 2006

The development of practical utilization way of water repelling technology for manufacturing of fruiting bag was main purpose of this study. The water repelling technology was developed by wax emulsion coating The wax emulsion was manufactured at Chungsan chemical(Co) on pilot scale. The coating paper was tried in plant coater of Agro(Co). The water repellency of wax emulsion coated paper was good as fruit bagging paper.

• Textile Coloration and Finishing
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• v.23 no.2
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• pp.100-106
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• 2011

UV-curable water-repellent finish was carried out to impart one-side repellency to the PET fabrics using a formulation of a UV-active fluorocarbon agent and a water soluble photoinitiator. The aqueous formulation was padded on the PET fabrics and it was subsequently UV-cured. The unirradiated side of the cured fabrics was made to wetteable to water by the prolonged UV/ozone irradiation. The influence of photoinitiator concentration, agent concentration and UV energy for photodegradation on the performance of the finished fabrics were investigated. The difference in the functional property of front and back sides was examined by measuring water repellency at each side of the treated fabrics, which resulted in four rating difference between two-side. The UV-cured and photodegraded PET surfaces were characterized by ATR, ESCA and FE-SEM.

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.577-584
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• 1996

Silicon oxide films with high hardness and water repellency were prepared by microwave plasma-enhanced CVD using four kind of organosilicon compound-fluoro-alkyl silane mixtures as source gases. An argon gas was used as a carrier gas for fluoro-alkyl silane. The substrate temperatures during deposition were controlled by resistant heating at a constant value between 50 and $300^{\circ}C$. The hardness of the films increased, but the deposition rate and the contact angle for a water drop decreased with increasing substrate temperature. The number of methoxy groups also affected the water repellency and hardness. The deposited films became more inorganic with increasing substrate temperature because of the thermal dissociation of reactants.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.76-77
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• 2021

compared and reviewed the water repellency and strength characteristics by controlling the surface stamping size and fine aggregate ratio of cement mortar mixed with water repellent as a method to control the ecological imitation surface structure. As a result of measuring the contact angle, the higher the ratio of fine aggregate, the larger the contact angle. The contact angle increased when the surface structure was changed by stamping, and increased as the stamping size became smaller. In the surface stamping of mesh#150, the contact angle was particularly increased.

• Proceedings of the Korean Society of Tobacco Science Conference
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• 2003.05a
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• pp.32-32
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• 2003