• Journal of the Korean Wood Science and Technology
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• 제35권5호
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• pp.67-75
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• 2007

As a part of abating the formaldehyde emission of urea-formaldehyde (UF) resin adhesive by lowering formaldehyde to urea (F/U) mole ratio, this study was conducted to investigate properties of UF resin adhesive with different F/U mole ratios. UF resin adhesives were synthesized at different F/U mole ratios of 1.6, 1.4, 1.2, and 1.0. Properties of UF resin adhesives measured were non-volatile solids content, pH level, viscosity, water tolerance, specific gravity, gel time and free formaldehyde content. In addition, a linear relationship between non-volatile solids content and sucrose concentration measured by a refractometer was established for a faster determination of the non-volatile solids content of UF resin. As F/U mole ratio was lowered, non-volatile solids content, pH, specific gravity, water tolerance, and gel time increased while free formaldehyde content and viscosity were decreased. These results suggested that the amount of free formaldehyde strongly affected the reactivity of UF resin. Lowering F/U mole ratio of UF resin as a way of abating formaldehyde emission consequently requires improving its reactivity.

• Journal of the Korean Wood Science and Technology
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• 제36권2호
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• pp.63-72
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• 2008

As a part of abating formaldehyde emission of urea-formaldehyde (UF) resin adhesive, this study was conducted to investigate chemical structures of UF resin adhesives with different formaldehyde/urea (F/U) mole ratios, using carbon-13 nuclear magnetic resonance ($^{13}C$-NMR) spectroscopy. UF resin adhesives were synthesized at four different F/U mole ratios such as 1.6, 1.4, 1.2, and 1.0 for the analysis. The analysis $^{13}C$-NMR spectroscopy showed that UF resin adhesives with higher F/U mole ratios (i.e., 1.6 and 1.4) had two distinctive peaks, indicating the presence of dimethylene ether linkages and methylene glycols, a dissolved form of free formaldehyde. But, these peaks were not detected at the UF resins with lower F/U mole ratios (i.e., 1.2 and 1.0). These chemical structures present at the UF resins with higher F/U mole ratios indicated that UF resin adhesive with higher F/U mole ratio had a greater contribution to the formaldehyde emission than that of lower F/U mole ratio. Uronic species were detected for all UF resins regardless of F/U mole ratios.

• 한국가구학회지
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• 제14권2호
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• pp.1-12
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• 2003

This study was carried out to determine the mechanical and physical properties of particle boards glued with condensed tannin (Wattle Tannin) powder that was single-molecule phenolic compounds like powdered phenolic resin. Our findings are; 1) It is necessary to spray water on the chip surfaces for effective application of powdered -form tannin resin. It shows that the best and optimum mat moisture increase is 14% of water spray on the surface of chips for developing PB properties. 2) In general, for both liquid and powdered tannin adhesives, their physical and mechanical properties has been proportional to the increase of resin level. But, the most efficient addition ratio is 16% of resin on dry basis. Specially, it is found that the resin level influences on the amount of free formaldehyde emission. The higher the resin level is, the lower the emission is. These phenomena seem to result from the increase of hexamine or formaline in the adhesives used as a hardener, that reduce the free-formaldehyde amount by reaction of tannin of poly-molecule and water. 3) The optimum condition for manufacturing PBs is the condition of hexamine of 5% and formaline of 6% in mechanical and physical properties. Hexamine is superior to formaline in mechanical and physical properties along with the control of the free formaldehyde emission amount. The result of NaOH's addition is insignificant in all experiments of both mechanical and physical properties.

• Journal of the Korean Wood Science and Technology
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• 제32권1호
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• pp.80-87
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• 2004

천연접착제인 분말상 탄닌수지를 사용한 파티클보드의 물리·기계적 성질의 개선을 위하여 분말상 탄닌수지와 액상 탄닌수지를 혼합하여 사용한 결과, 30:70 (분말 : 액상)의 혼합비가 최적조건이었으며 분말상 탄닌 수지의 비율이 높으면 물성이 저하되는 현상을 볼 수 있었으며 또한 포름알데히드 방산량이 E₀ 수준의 고내수성 제품을 제조할 수 있었다. 한편 요소수지 및 멜라민수지와 분말상 탄닌 수지와의 혼합방법은 물리·기계적 성질의 개선에 영향을 주지 못했으며, 유리포름알데히드 방산에 대한 scavenger의 역할만을 하였다.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.72-78
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• 1999

요소 멜라민수지의 조성에 의한 속경화의 가능성, 경화촉진제의 첨가에 의한 경화촉진 효과 및 접착성능에 대하여 검토하였다. 수지조성과 동시반응에 의해 제조한 UMF 수지의 겔화성과의 관계는 요소(멜라민/요소 몰비=0.2)에 대한 포롬알데히드의 몰비가 증가할수록 겔화시간이 빨라졌다. 그러나, 요소에 대한 포름알데히드의 몰비가 2.5이상에서는 수지중의 유리포름알데히드량이 KS기준에 합격하지 못하므로 속경화를 위해 수지 합성시 포름알데히드의 첨가량을 높이는 것은 어려울 것으로 생각된다. 또한, 요소에 대한 포름알데히드의 몰비를 3.4로 고정한 UMF수지에 있어서 요소에 대한 멜라민의 몰비가 0.3에서 0.6으로 증가할 수록 수지의 겔화시간은 다소 단축되었으나, 0.6이상에서는 다시 증가하였다. UMF수지의 겔화성과 접착강도는 경화제로서 염화암모늄과 p-툴루맨설폰산, 증량제로서 소액분과 콘글루텐의 병용에 의해 크게 향상되었다.

• 접착 및 계면
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• 제12권4호
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• pp.125-132
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• 2011

최근 실내공간에서의 안전성을 확보하기 위해 유해물질의 방출이 없는 천연재료의 사용이 요구됨에 따라 음식재료인 마늘을 이용한 도배용 천연마늘접착제의 제조와 그 성능에 관하여 검토하였다. 마늘을 이용한 천연접착제는 생마늘을 물로 추출하여 탄수화물과 단백질을 분리 및 농축하는 방법에 의해 제조가 가능하였다. 제조한 천연마늘접착제의 접착성능은 불휘발분의 양에 의해 크게 영향 받았으며, 최적의 불휘발분은 60% 전후였다. 제조한 천연마늘 수지의 특성은 불휘발분 62%, 밀도 $1.3g/cm^3$, 점도 2,789 mPa s, pH 6.6이었다. 또한, 마늘 접착제의 접착성능은 KS의 기준을 크게 상회하였으며, 방부제의 첨가 없이도 마늘이 가지고 있는 항균성을 유지하고 있었으며, 특히 휘발성유기화합물과 폼알데하이드의 방산이 거의 없는 매우 안전한 천연접착제로서의 이용이 가능할 것으로 기대된다.

• 한국응용과학기술학회지
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• 제30권3호
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• pp.551-559
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• 2013

To investigate the adhesion effect of sodium bisulfite content in making blocked isocyanate, wood adhesive PB-1, PB-2, PB-3 and PB-4 containing sodium bisulfite content of 15%, 22.5%, 30% and 37.5% were synthesized respectively. As a result, when the amount of sodium bisulfite increased in adhesives, the tensile strength was found to be proportionally increased. The final adhesive mixtures were manufactured using a two-components system which are prepared by mixing two separate protein and BI solutions due to the precipitate in the adhesives. As PVA was added to adhesives to increase tenacity, the plywood dehiscence phenomenon after cold pressing process was declined. By addition of PVA, the tensile strength was improved up to $6.5{\sim}7kgf/cm^2$ with BI/protein ratio from 1:6 up to 1:8. Phase separation between milk fat and aqueous layer was disappeared after addition of emulsifier, Tween 20. Additon of Tween 20 showed tensile strength up to $5{\sim}6.5 kgf/cm^2$ at NCO/protein ratio of 1:12 ~ 1:14 without phase separation.

• 한국응용과학기술학회지
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• 제32권4호
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• pp.607-615
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• 2015

To investigate the adhesion effect of various kinds and contents of polymeric methylene diphenyl diisocyanates (pMDIs) on adhesion performance, wood adhesives (A-1~5) were synthesized and characterized. As results, when the amount of pMDI increased in adhesives, the dry tensile strength was found to be proportionally increased sustaining at around $16.0{\sim}21.6kgf/cm^2$. The polyurethane (PU) resin, which used M11S as a source of pMDI showed the best wet tensile strength at $11.9kgf/cm^2$ and cyclic boil tensile strength at $8.1kgf/cm^2$, which satisfied the requirement of over $7kgf/cm^2$. Thermal properties of the rice powder (RP) based polyurethane resins were characterized by differential scanning calorimetry (DSC) and Thermal gravimetric analysis (TGA). Thermal stability of polyurethane resins increased to $250^{\circ}C$ with adding pMDIs. The more pMDI (M5S) was added to adhesive, the higher thermal stability of the resin was observed by TGA.

• 공업화학
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• 제24권2호
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• pp.171-176
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• 2013

지구온난화 문제가 대두되면서 volatile organic compound (VOC) free 도료의 필요성이 크게 증가하고 있다. 현재 국내외적으로 사용되고 있는 도료의 약 70~80% 정도가 용매형 도료이다. 따라서 지구온난화 문제의 근본적인 해결을 위해서는 도료의 희석제로 사용되고 있는 용매인 휘발성 유기화합물(VOCs)의 배출을 최소화 할 수 있는 무용제형도료의 개발이 필수적이다. 본 연구에서는 무용제도료를 개발하기 위하여 기존의 페놀수지의 특성인 산성화로 인해 도료로 사용 시 부착성이 떨어지는 단점을 보완하기 위해 아크릴계 단량체들을 첨가하였다. 합성한 페놀수지와 PF/PMMA 블렌드 수지와 PF/PHEMA 블렌드 수지의 구조분석결과 블렌드된 형태를 확인하였고 접착인장강도실험을 통해 PF/PMMA 블렌드 수지가 2.818 Mpa의 값으로 도료시스템에 적용 가능성을 확인하였다.