• 공업화학
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• 제10권5호
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• pp.731-736
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• 1999

식물성 천연 유지인 콩기름을 peracetic acid로 에폭시화 시킨 후에 황산 촉매 하에서 메탄올과 반응시켜서 OH-value가 186(mg KOH/g)인 폴리올을 합성하였다. 합성한 폴리올에 계면활성제로는 silicon계 B-8409를, 발포제로는 증류수를, 촉매로는 dimethylcyclohexylamine을, 이소시아네이트로는 polymeric MDI를 사용하여 폴리우레탄 포옴을 합성하였다. 형성된 포옴의 밀도, 압축강도, 압축탄성률, cell의 구조 등을 조사하였다. MDI의 당량비를 변화시켜 가며 포옴을 형성시켜 보았으며, MDI index를 105로 고정하고, 발포제, 계면활성제, 촉매의 양을 각각 변화시켜 가며 포옴을 형성시켜 보았다. MDI index가 증가할수록 밀도와 압축 물성이 증가하였다.

• Elastomers and Composites
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• 제58권3호
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• pp.121-127
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• 2023

The effect of diisocyanate type on the decomposition temperature of polyurethane (PU) hydrolysis was investigated in a subcritical water medium up to 250℃. PU samples were prepared using different types of diisocyanate: two aromatic diisocyanates (4,4'-methylene diphenyl diisocyanate (MDI) and methyl phenylene diisocyanate (TDI)), one unbranched aliphatic diisocyanate (hexamethylene diisocyanate (HDI)), and two cyclic aliphatic diisocyanates (4,4'-methylene dicyclohexyl diisocyanate (H₁₂MDI) and isophorone diisocyanate (IPDI)). The pressure had no effect on hydrolysis in the range of 70-250 bar. The decomposition temperature of the PU samples increased in the following order: TDI-PU (199℃) < H₁₂MDI ≈ IPDI ≈ HDI (218-220℃) < MDI-PU (237℃). This order of increase in temperature is related to the electron-donating ability of the group to connected to the nitrogen of the urethane unit. When the temperature of the (PU + water) mixture reached the specific decomposition temperature, the PU samples hydrolyzed completely within 5 min into primary amine and 1,4-butanediol. The hydrolysis products from MDI-PU and H₁₂MDI-PU were separated into a liquid phase rich in (BD + water) and a solid low phase rich in amine, whereas the products from TDI-, IPDI-, and HDI-PU existed in a single aqueous phase.

• Elastomers and Composites
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• 제58권2호
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• pp.70-80
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• 2023

The effect of phenylphosphonic acid (PPOA) on polyurethane (PU) thermal stability was studied through Fourier transform infrared spectroscopy and Thermogravimetric analysis. To synthesize PPOA-modified PUs (PPOA-PUs), polyether-type diols (Mw=62, 106, 190, 419, 605) were chemically modified with PPOA and then reacted with 4,4'-dicyclohexylmethane diisocyanate (H₁₂MDI) and 4,4-diphenylmethane diisocyanate (MDI). During thermal decomposition in air, the PPOA embedded in the PUs formed intumescent phosphocarbonaceous char. Below 400℃, PPOA-H₁₂MDI-PUs were more unstable, as PPOA decomposed at lower temperatures than phenyl groups and aliphatic ethers. Above 550℃, the thermal stability of PUs followed this order: PPOA-MDI-PUs > PPOA-H₁₂MDI-PUs > MDI-PUs > H₁₂MDI-PUs. At 700℃, unmodified PUs had no residue, while the PPOA-MDI-PU residue was 4.4~23.0 wt.% and the PPOA-H₁₂MDI-PU residue was 1.5~17.5 wt.%. The enhanced thermal stability of PPOA-MDI-PUs at high temperatures can be attributed to the synergetic effect of PPOA and phenyl groups on the formation of phosphocarbonaceous char.

• 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.

• Elastomers and Composites
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• 제49권3호
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• pp.245-252
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• 2014

폴리올, 이소시아네이트, 2-HEMA 및 기타 아크릴레이트 단량체들로부터 제조된 폴리우레탄 접착제의 FT-IR측정과 물성을 검토하였다. 폴리우레탄 접착제의 연화점, 점도, 접착강도 및 기계적 물성들이 각각 링과볼법, Brookfield 점도계 및 만능시험기를 이용하여 검토되었다. 실험 결과에 의하면 PPG 함량 및 부틸아크릴레이트 함량이 증가함에 따라 연화점, 접착강도, 인장강도 및 100% modulus 값 등은 감소하는 것을 보여준다. 하지만 2-HEMA 및 MDI량이 증가할수록 인장강도 및 100% modulus값 등은 증가하였으며 점도와 NCO함량 등도 또한 증가하였다.

• 접착 및 계면
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• 제7권4호
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• pp.53-59
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• 2006

The paper highlights technical advances and introduces recent innovations such as smart curing laminating adhesives for flexible packaging with low migration rates of aromatic isocyanates and amines. Latent reactive one-part systems on the basis of surface deactivated solid isocyanates open up new dimensions for heat setting adhesives and waterborne PU dispersions. The new generation of Purmelt Micro Emission adhesives contains less than 0.1% of MDI monomer, thereby drastically reducing the emission of hazardous isocyanate vapors during processing and setting a significantly improved technical standard in occupational safety. Once again, polyurethane adhesives have demonstrated their unique ability to adapt to new process, product, safety and environmental requirements.

• Transactions on Electrical and Electronic Materials
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• 제18권4호
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• pp.211-216
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• 2017

The dielectric properties of two polyurethanes (PUs) with different hard segments, i.e., aromatic methylene di-p-phenyl diisocyanate (MDI) and aliphatic hexamethylene diisocyanate (HDI), were investigated in the temperature range of -100 to $100^{\circ}C$ and in the frequency range of 1 Hz to 3 kHz. The ${\alpha}$-relaxations induced by the glass transition of the equivalent soft segments in the two PUs occurred at relaxation times of ${\tau}=3.46{\times}10^{-3}s$ for MDI-PU and ${\tau}=3.39{\times}10^{-2}s$ for HDI-PU at $-20^{\circ}C$, in accord with the temperature-frequency superposition principle, resulting in similar shifting factors. However, different I-relaxations were observed for the two PUs. The I-relaxation of MDI-PU occurred due to the mobility of the chain extenders near $80^{\circ}C$ with a slower shifting rate than the ${\alpha}$-relaxation. On the other hand, I-relaxation arising from both the extender and the unconstrained hard segments of HDI-PU occurred at $70{\sim}100^{\circ}C$, indicating complicated dielectric behavior due to partial interaction with the ${\alpha}$-relaxation at high frequencies. Thus, the I-relaxation of HDI-PU did not follow the superposition principle. The dielectric behaviors of the PUs were mainly influenced by their phase transitions, which were affected by the structure and components of the materials.

• Fibers and Polymers
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• 제2권3호
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• pp.141-147
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• 2001

The effect of compositions of isophorone diisocyanate (IPDl)/4.4'-diphenylmethane diisocyalate (MDI) and polypropylene oxide diol (PPG, $M_w$: 3000)/1,4-butane diol (BD) on the properties of UV-cured polyurethane acrylate films based on 2-hydroxyethyl acrylate (HEA) was examined. UV-curable polyurethane acrylates were formulated from the prepolymer. trimethylol propane triacrylate (TMPTA) as a reactive diluent, and 1-hydroxycyclohexyl ketone (Irgacure 184) as a photoinitiator. Dynamic mechanical thermal properties and elastic properties of UV-cured polyurethane acrylates was fecund to depend on the chemical composition of IPDl/MDl and PPG/BD. As the BD content increased, the tensile storage modulus of all series samples increased significantly. The storage modulus increased in the order of samples A (IPDI based samples)> samples B (IPDI/MDl (7/3 molar ratio) based samples) > samples C (IPDI/MDl (5/5 molar ratio) based samples at the same composition. Two distinct louts modulus peaks for all samples are observed owing to the softs segment glass transition temperature ($T_gh$) and hard segment glass transition temperature ($T_gh$). The difference between $T_gh$, and $T_gh$, (Δ$T_g$) increases in the order of A > B > C at the same composition. In cycle test, the initial onset strain (%) was found to decrease with increasing BD content in PPG/BD and with increasing MDI content in IPDI/MDl.

• 접착 및 계면
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• 제13권3호
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• pp.116-120
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• 2012

본 연구에서는 수분산 폴리우레탄의 내가수분해성을 개선하기 위하여 polyester polyol, $H_{12}MDI$, DMPA 및 sulfopropylated polypropyleneglycol-${\alpha}$,${\omega}$-diamine (SP)을 사용하여 수분산 폴리우레탄을 합성하였다. 유리전이온도는 SP 함량의 증가에 따라 증가하다가 NCO/OH 비가 1.8에서는 감소하였다. 또한 SP의 함량이 증가함에 따라 인장강도와 내가수분해성은 증가하는 경향을 나타내었으며, SP로 사슬연장한 WPU-SP에서 인장강도 감소율은 약 WPU-SP-1을 제외한 나머지에서 약 2~5%정도로 내가수분해성이 향상되었다.

• Elastomers and Composites
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• 제34권5호
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• pp.399-406
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• 1999

Polytetramethylene ether glycol (PTMG)와 4,4'-diphenylmethane diisocyanate (MDI), toluene 2,4-diisocyanate(TDI), isophoron diisocyanate(IPDI)로 polyurethane (PU) prepolymer를 합성하고, dimethylol propionic acid(DMPA)로 쇄연장시킨 후 triethyl amine(TEA)으로 중화시켜서 안정한 수분산성의 음이온성 폴리우레탄을 제조하였다. 음이온성 폴리우레탄의 합성과정에서 쇄연장제의 함량과 중화비에 따른 에멀젼의 유화안정성, 접착강도, 점도, 유리전이온도 및 cast film의 물리적 성질을 UTM, Viscometer와 DSC를 사용하여 검토하였다.