• 공업화학
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• 제16권2호
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• pp.288-291
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• 2005

Resol형 페놀수지(phenol-formaldehyde (PF) resin)는 페놀(phenol: P)에 포름알데히드(formaldehyde: F)를 첨가하여 반응시키는 부가반응과 물을 제거하는 축합반응에 의해 합성된다. 본 연구에서는 부가반응 반응변수인 F/P몰비, 촉매의 농도, 반응온도 및 반응시간 등의 영향에 관하여 연구하였다. 또한 반응시간의 조절에 따른 합성된 페놀수지의 분자량과 점도에 미치는 영향을 조사하였다. 실험결과, 부가반응에서 촉매농도와 반응온도가 높아질수록 반응시간은 크게 감소되는 경향을 나타내었다. 또한 축합반응에서 페놀수지의 점도는 반응시간이 증가할수록 1500cps에서 9000 cps까지 증가하였고, 분자량은 500~1100 g/mol 범위의 저 분자량을 나타내었다.

• 한국응용과학기술학회지
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• 제24권4호
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• pp.339-346
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• 2007

The influence of adding urea to phenol-formaldehyde (PF) resins as a co-polymer component were investigated aiming at synthesizing useful phenol-urea-formaldehyde resins. Urea was added at 10% by total resin weight. Several methods for the addition of urea to the PF resins during synthesizing resins to see the co-polymerization occurs between urea and PF resins. The urea was added at the beginning, at three different middle stages, and at the end of PF resin synthesis. The copolymerized methylene bridges between phenol and urea molecules were not observed by $^{13}C-NMR;$ no signal around 50ppm. The curing of urea-modified PF resins, evaluated by dynamic mechanical analysis(DMA), showed some differences among the resins. DMA gel times ranged from 2.75 min to 3.25 min and the resins made with earlier urea additions showed slightly shorter gel times. The longest cure time and gelation time was observed for the resin PFU. Catalyst effects on the DMA cure time values of resins were not significant with different amounts of catalyst or different types of catalyst for all resins tested. Gel times of urea-modified PF resins shortened the most by triacetin catalyst.

• Journal of the Korean Wood Science and Technology
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• 제32권3호
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• pp.25-32
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• 2004

This research work explored physical and mechanical properties of impregnated sawdust boards from three softwood species (P, densifora, L. kaemferi, and P. koraiensis) with phenol-formaldehyde (PF) resin by various vacuum treatment methods of combining pressure, vacuum, and ultrasonic waves. Simultaneous vacuum and ultrasonic wave treatments with no pressure resulted in the greatest increase in resin content, density, dimensional changes (thickness and length), bending strength, and hardness of impregnated board. This result seemed to be attributed to the ultrasonic wave treatment.

• Journal of the Korean Wood Science and Technology
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• 제44권6호
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• pp.842-851
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• 2016

The objective of this study was to improve physical and mechanical properties of soft-inner part of oil palm trunk (S-OPT) after impregnation with phenol formaldehyde (PF) resin and densification by close system compression (CSC) method. Effect of different methods of PF resin impregnation (i.e., no vacuum-pressure, vacuum, and vacuum-pressure) was evaluated. The results showed that PF resin impregnation and CSC significantly improved the physical and mechanical properties of S-OPT up to: (1) 176% in density; (2) 309% in modulus of rupture (MOR); (3) 287% modulus of elasticity (MOE); and (4) 191% in the compressive strength. Physical and mechanical properties of S-OPT showed their best performances when PF resin impregnated with vacuum-pressure method as shown by higher weight gain, density, MOR, MOE, compressive strength, and lower recovery of set due to better penetration of PF resin into S-OPT. Combining PF resin impregnation and densification by CSC method could be a good method to improve physical and mechanical properties of S-OPT.

• Journal of the Korean Wood Science and Technology
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• 제35권6호
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• pp.108-117
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• 2007

생장 기간이 매우 빠르고 섬유방향의 강도적 성질이 우수한 대나무를 합판의 원료로 이용하기 위하여 케루잉단판-솜대 zephyr 복합 패널(WBCB)의 제조 조건(수지접착제의 종류, 도포량, 도포방법)이 패널의 성능에 미치는 영향을 검토하였다. 수지의 종류에 따른 5-ply WBCB의 성능은 폴리메릭 이소시아네이트수지(PMDI)가 가장 좋은 결과를 나타내었으며, 이어 페놀수지(PF), 페놀 멜라민수지, 요소 멜라민수지 및 요소수지의 순이었다. 사용한 수지 중 강도적 측면과 작업성을 고려할 때 PF 수지에 의한 복합 패널 제조가 가장 적절한 것으로 생각된다. PF수지를 사용하여 제조한 12 mm 두께의 5-ply WBCB의 경우, 수지의 도포량이 증가하면 패널의 성능도 향상되는 경향이었다. 또한 박리강도 측정 후의 파괴양상은 도포량이 증가함에 따라 대나무 외층-대나무 내층 경계층의 파괴가 증가한 데 반하여 대나무 제퍼 내부층의 파괴는 상대적으로 감소하였다. 따라서 WBCB 제조시 수지가 다소 zephyr 내부까지 침투할 정도의 수지 도포량이 적절한 것으로 생각되며, 표면 단판의 오염성과 경제성 등을 고려할 때 $320g/m^2$이 가장 적합한 것으로 판단된다. 동일한 PF수지 도포량에서 수지의 도포방법을 달리하여 제조한 5-ply 복합 패널의 성능은 양면과 편면 스프레이 도포 간과 스프레이와 롤러에 의한 도포방법 간에 현저한 차이가 나타나지 않아 주어진 환경에서 작업성이 좋은 도포방법을 채택하면 될 것으로 생각된다.

• Journal of the Korean Wood Science and Technology
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• 제24권2호
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• pp.15-19
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• 1996

To utilize the waste materials and develope wood adhesive from isolated bloods of slaughtered cow and pig and also to prevent water pollution, simple and rapid method of isolation and purification of plasma proteins from pig bloods with trichloroacetic acid(TCA) treatment was developed. Adding of TCA-precipitated blood powder to the phenol formaldehyde resin(PF) improved dry and wet strength of plywood and resulted in fast hot pressing times.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.722-731
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• 2020

The purpose of this research is to determine the efficiency of impregnation using phenol formaldehyde resin to enhance Falcataria wood's stability and better mechanical properties. Impregnation process was carried out after moisture content stabilized at 12% on samples with a dimension of 20 mm × 20 mm × 300 mm at various concentrations and pressure time. Dimensional stability was evaluated by thickness swelling (TS) and anti-swelling efficiency (ASE) and the young's modulus was conducted according to BS 573. The mechanical properties and dimensional stability of impregnated wood were evaluated. Dimensional stability and mechanical properties of Falcataria wood were successfully increased after impregnation. PF impregnation can improve the mechanical properties and the density from 0.26 g/㎤ to 0.30 g/㎤ even with only 10% of weight percent grain. Dimensional stability increases with increasing resin concentration and time pressure. The highest increase in mechanical properties was found at a higher concentration of PF. The penetration of PF into the wood's cell darkens the color of impregnated wood.

• Journal of the Korean Wood Science and Technology
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• 제33권5호통권133호
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• pp.66-75
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• 2005

Soybean-based adhesives have recently been reconsidered as alternatives to petroleum-based adhesives due to the uncertainty of availability of petrochemical products and the increased demand for wood adhesives. This study was conducted to investigate the adhesive properties of alkaline phenolic soy (APS) resin for hybrid poplar flakeboard. The APS resin was formulated by crosslinking an alkaline soy flour hydrolyzate with lab-prepared PF resin in the soy hydrolyzate to PF resin weight ratios of 70/30, 60/40, and 50/50. The APS resins were used to fabricate homogeneous hybrid poplar flakeboards with different resin solid levels (5%, 7%, and 9%), press temperatures (175 and $200^{\circ}C$), and press times of 8 and 10 minutes. The IB, wet MOR, and dimensional stability properties of board improved with increasing press time, press temperature, and PF level in APS resins. Increasing press time can be used to offset poor IB strength associated with a 9% resin solid level and the excessive moisture content in the mat. The following conditions were concluded to meet the requirements of the CSA standard for exterior-grade flakeboard: a 50% PF level, a 5% resin content, a $200^{\circ}C$ press temperature, and an 8 minute press time.

• Journal of the Korean Wood Science and Technology
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• 제27권1호
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• pp.64-71
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• 1999

본 연구는 통상적으로 충밀도 섬유판 제조에 사용되고있는 요소수지를 페놀수지로 대체함으로써 그 장단점을 찾아 보기 위해 실행되었다. 페놀수지을 이용해 제조한 중밀도 섬유판의 성능은 표준 요건을 충족시켰으며 높은 내구성을 보였다. 아울러 24 시간 냉수 침적후 두께팽창은 2 퍼센트 이하로 낮게 나타났다. 요소수지를 페놀수지로 대체했을 경우 단점들은 비교적 높은 수지함량 (8% 섬유전건종량기준)과 긴 열압시간 (7 분)으로 판명되었다. 이러한 결과들은 페놀수지을 사용한 중밀도 섬유판제조시 열압공정의 최적화가 되어야함을 시사하였다.

• Journal of the Korean Wood Science and Technology
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• 제40권2호
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• pp.110-122
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• 2012

This study investigated the effects of layered clay on the thermal curing behavior and tensile properties of resole phenol-formaldehyde (PF) resin/clay/cellulose nanocomposites. The thermal curing behavior of the nanocomposite was characterized using conventional differential scanning calorimetry (DSC) and temperature modulated (TMDSC). The addition of clay was found to accelerate resin curing, as measured by peak temperature ($T_p$) and heat of reaction (${\Delta}H$) of the nanocomposite’ curing reaction increasing clay addition decreased $T_p$ with a minimum at 3~5% clay. However, the reversing heat flow and heat capacity showed that the clay addition up to 3% delayed the vitrification process of the resole PF resin in the nanocomposite, indicating an inhibition effect of the clay on curing in the later stages of the reaction. Three different methods were employed to determineactivation energies for the curing reaction of the nanocomposite. Both the Ozawa and Kissinger methods showed the lowest activation energy (E) at 3% clay content. Using the isoconversional method, the activation energy ($E_{\alpha}$) as a function of the degree of conversion was measured and showed that as the degree of cure increased, the $E_{\alpha}$ showed a gradual decrease, and gave the lowest value at 3% nanoclay. The addition of clay improved the tensile strengths of the nanocomposites, although a slight decrease in the elongation at break was observed as the clay content increased. These results demonstrated that the addition of clay to resole PF resins accelerate the curing behavior of the nanocomposites with an optimum level of 3% clay based on the balance between the cure kinetics and tensile properties.