外文翻译_水性涂料.docx

此文档收集于网络，如有侵权，请联系网站删除Progress in Organic Coatings 77 (2014) 315321Contents lists available at ScienceDirectProgress in Organic Coatingsjou rn al hom ep age: /locate/porgcoat Preparation and properties of waterborne polyurethane/epoxy resin composite coating from anionic terpene-based polyol dispersionGuo-min Wu a,b, , Zhen-wu Kong a,b, , Jian Chen a , Shu-ping Huo a , Gui-feng Liu a,ba Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Key Laboratory of Biomass Energy and Material of Jiangsu Province, Key and Open Laboratory on Forest Chemical Engineering, State Forestry Administration, National Engineering Laboratory for Biomass Chemical Utilization,Nanjing 210042, Chinab Research Institute of New Technology, Chinese Academy of Forestry, Beijing 10091, China此文档仅供学习与交流a r t i c l ei n f oa b s t r a c tArticle history:Received 22 July 2013Received in revised form 9 September 2013 Accepted 20 October 2013Available online 14 November 2013Keywords:PolyolWaterborne polyurethane Epoxy resinComposite TerpeneAn anionic polyol (T-PABA) dispersion was prepared by modifying terpene-based epoxy resin with para- aminobenzoic acid. Then T-PABA dispersion was crosslinked with a hexamethylene diisocyanate (HDI) tripolymer to prepare waterborne polyurethane/epoxy resin composite coating. The rheological proper- ties and particle size distribution of the composite system were characterized by rotary rheometer and laser particle size analyzer. The crosslinked composite product has good thermal resistant properties, with glass-transition temperatures (Tg ) about 40% and 50% weight loss temperatures (Td ) in the range of 400420. The smooth and transparent lm obtained from the composite product has good exibility, adhesion, impact strength, antifouling and blocking resistance properties. The impact strength, pencil hardness, water-resistant and thermal-resistant properties of the composite products increased with the molar ratio of isocyanate group to active hydrogen of T-PABA. 2013 Elsevier B.V. All rights reserved.1. IntroductionConventional solvent-based polyurethanes, with their excel- lent outdoor durability, outstanding chemical resistance and very good mechanical properties, are successfully used in various applications, such as original equipment manufacturer (OEM) coats, automotive repair coatings, industrial paints, furniture lac- quers, plastic coatings and adhesives 1,2. Recently, controlling the emission of volatile organic compounds (VOCs) is becoming the important driving force for resin developments. The substi- tution of solvent-based coatings with water-dispersed coatings is a major approach to reduce VOC emission. Two-component waterborne polyurethanes (2K-WPUs) coatings which integrate the environment-friendly property of water-dispersed coatings with the high performance of two-component polyurethanes, are gaining extensive research attention 36. 2K-WPUs comprise a polyisocyanate component and a waterborne polyol compo- nent which results in various performances of the 2K-WPUs due to the various structures of the polyols. The most com- monly used waterborne polyol is polyacrylate polyol which has been applied widely in the eld of coatings and adhesive Corresponding author at: No. 16, Suojin Wucun, Nanjing 210042, PR China.E-mail addresses: (G.-m. Wu), (Z.-w. Kong).79. However, the polyacrylate polymer has some shortcomings such as bad temperature adapt property and organic solvent resistibility. Polyurethane polyol is another promising hydroxyl group component for 2K-WPUs with its high comprehensive properties, while the use-cost of polyurethane polyol is quite expensive 10,11.Most of these polyol components for 2K-WPUs originate from the unrenewable fossil resource. With the fossil resource being exhausted, the utilization of biomass resource for preparing poly- mer materials has been paid more attention to by many scholars all over the world 12,13. Terpene-based epoxy resin (TME), an alicyclic epoxy resin with endocyclic structure, was synthesized from the raw material turpentine 14,15. Recent investigations showed that it could also serve as precursors for the synthesis of TME-based polyols which could be crosslinked with polyisocyanate to prepare polyurethane/epoxy resin composite polymers 16. In this article, an anionic polyol (T-PABA) dispersion was synthesized by reacting TME with para-aminobenzoic acid (PABA). Then a new two-component waterborne polyurethaneepoxy resin compos- ite coating was prepared by crosslinking T-PABA dispersion with polyisocyanate. The purpose of this study was in order to obtain a wonderful composite polymer product from the bioresource tur- pentine, which could combine the rigidity and heat resistance of the epoxy resin (TME), the exibility and tenacity of the polyurethane and the environmental friendliness and safety of the waterborne systems together.0300-9440/$ see front matter 2013 Elsevier B.V. All rights reserved./10.1016/j.porgcoat.2013.10.005Table 1Physicochemical parameters of T-PABA and T-PABA dispersionT-PABA (solid resin)AppearanceYellow transparent solidHydroxyl value (mg g-1 )168.9Amine value (mg g-1 )125.9Active hydrogen content (mmol g-1 )5.254T-PABA dispersionAppearanceYellow transparent liquidSolid content (%)30Viscosity (mPa s, 25 C)400Average particle size (nm)40StabilityNo delaminating after 6 months2. Materials and methods2.1. MaterialsThe base material was the terpene-maleic ester-type epoxy resin (TME) with epoxy value of 0.340.38 mol 100 g1, whichwas synthesized form turpentine 14. Para-aminobenzoic acid (PABA), technical grade, was purchased from Changzhou Sunlight Pharmacy Industry Co., Ltd., China. N,N-dimethyl ethanolamine and 2-butanone, chemically pure, were purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd., China. The hydrophilically modied hexamethylene diisocyanate (HDI) tripolymer (Fig. 1) with isocyanate (NCO) group content of 14 wt% and solid content of 85 wt%, technical grade, was supplied by Shanghai Sisheng Polymer Materials Co., Ltd., China.2.2. Synthesis of T-PABA and T-PAB dispersionA 500 ml four-necked ask equipped with stirrer, thermometer, condenser and heating mantle was charged with 30.6 g TME, 10.6 g PABA, and 16.5 g 2-butanone. After the PABA was all resolved in the 2-butanone under heating and stired, the reaction was contin-ued for 4 h at 8090 C. The 2-butanone was removed with vacuumdistillation after reaction. The product (T-PABA) was neutralized with 4.8 g N,N-dimethyl ethanolamine, then dispersed with 96.0 gdistilled water by churning at 5001000 rpm, at 5070 C. A yel-low transparent anionic dispersion (T-PABA dispersion) with solid content of 30% was obtained (Scheme 1). The physicochemical parameters of T-PABA and T-PABA dispersion were described in Table 1.2.3. Preparation of the composite coatingA composite dispersion was prepared by mixing T-PABA disper- sion with the hydrophilically modied HDI tripolymer at the molar ratio of active hydrogen to isocyanate group ranging from 0.8 to1.4. The solid content of the blending was about 32% (by mass) as applied in this work. After mixed, the blending was cast on tin-plates or glass slides to form 40 m (3 m) thick dry lms. Thecrosslinked product of the composite dispersion was obtained by keeping the lms in the room temperature for 24 h and then curingthem in an oven at 70 C for 6 h.2.4. MeasurementsNicolet IS10 infrared spectrometric analyzer (Nicolet Instru- ment Co., U.S.A) was used to record the FT-IR spectra of polyol andcomposite product samples in the range of 4004000 cm1.13C NMR spectra were recorded on Bruker AV-300 NMR spec- trometer at 300 MHz. Deuteroacetone was used as a solvent and tetramethylsilane (TMS) was served as internal standard.Rheological properties of the T-PABA dispersion (30% solid content) and the composite dispersion (32% solid content) were performed with a Haake Mars-III rotational rheometer using coaxial cylinder technique.Particle size analysis was carried out on a Nano-ZS ZEN3600 Zeta-sizer (Malvern Instrument Co., UK). The T-PABA dispersion and the composite dispersion were diluted with distilled water to 0.5% solid content.The morphology of the composite product was characterized by atomic force microscope (AFM) performed on a SPM9600 AFM (Shimadzu, Japan). To prepare AFM sample, the composite sample was cast a lm on silicon substrate.Mechanical properties of the composite product were evaluated according to standard test methods (impact strength GB/T 1732- 93 17, adhesion GB/T 1720-89 18, exibility GB/T 1731-93 19, pencil hardness GB/T 6739-96 20). Water resistance, antifoul- ing and blocking resistance properties are measured according to standard test method GB/T 23999-2009 21.PerkinElmer Diamond differential scanning calorimeter (U.S.A) was used to record the differential scanning calorimetry (DSC) ther-mograms of the composite products at a heating rate of 20 C min1under a nitrogen gas ow of 20 ml min1.NETZSCH STA 409 PC/PG thermogravimetric analyzer (Germany) was used to perform thermogravimetric analysis(TGA) of the composite products at a heating rate of 10 C min1under a nitrogen atmosphere.3. Results and discussion3.1. Characterization of T-PABAThe synthesis of T-PABA was carried out with the addition reac- tion between oxirane group and primary amine group (Scheme 1). The chemical structure of T-PABA was characterized with FT- IR (Fig. 2) and 13C NMR (Fig. 3) spectra. Compared with the spectra of TME, the signicant enhancement of O H stretch-ing peak at 3480 cm1 and the disappearance of the absorptionpeak at 908 cm1 in the spectra of T-PABA denoted the occur-rence of addition reaction of oxirane ring and amine group 22. FT-IR spectra of T-PABA show signication absorption peaks at32003700 cm1 (N H and O H stretching), 24002800 cm1and 1680 cm1 (COOH stretching), 1605 and 1530 cm1 (benzeneFig. 1. Chemical structure of the hydrophilically modied HDI tripolymer.Scheme 1. Preparation of T-PABA and T-PABA dispersion.ring stretching), 1730 cm1 (C O stretching), 1273 cm1 (C N stretching of aromatic amine), and 1117 cm1 (C O stretching ofsecondary hydroxyl group), which match the chemical structure characteristic of T-PABA correctly.13C NMR spectra were used to further demonstrate the chemicalstructure of T-PABA. The characteristic single peaks of the oxi- rane ring (C1 and C2 in TME) at about = 43.5 ppm and 48.5 ppm were disappeared in the 13C NMR spectra of T-PABA 23. After the reaction between oxirane group and primary amine group, the of C1 and C2 shifted the low frequency region, and appearedat about = 46.9 ppm and 63.9 ppm (C1I and C2I in T-PABA). Thepeaks at about 112 ppm, 113.5 ppm, 118.4 ppm, 132 ppm, and154 ppm show the typical benzene ring absorptions, and the peak at 168.4 ppm exhibits the absorption of the carboxyl group.3.2. Rheological properties of the T-PABA dispersion and the composite dispersionRheological properties are important for the use and storage of dispersions when applied as coatings and adhesives. Rheological behavior can be characterized by power-law equation 24: = Ky n or Ky n1(1)Fig. 2. FT-IR spectra of T-PABA and TME.Fig. 3. 13 C NMR spectra of T-PABA and TME.where is shear stress, K is viscosity coefcient, y is shear rate, nis ow behavior index, and is apparent viscosity.The logarithmic form of power-law equation can be written, log = log K + n log y(2)The factor n can be obtained graphically from the slope of the log log y line from linear regression. Fig. 4 shows the rheologi-cal curves of the T-PABA dispersion and the composite dispersion at 25 C, and correspondingly Fig. 5 shows the log log y lines. It canbe seen from Fig. 4, the apparent viscosity of the T-PABA dispersion and the composite dispersion remained constant with the increas- ing of shear rate. Because the particles of the T-PABA dispersion and the composite dispersion are both charged particles, interac- tion force among particles is strong enough to stand against the shear stress in our measurement. As shown in Fig. 5, the obtained log has good linear correlation with log y , and the values of theFig. 4. Rheological curves of T-PABA and the composite dispersions.ow behavior index n equals approximately 1, which indicates the dispersions are Newton uids.3.3. Particle size analysis of the dispersionsThe lm formation process of waterborne resin contains occu- lation and merging phenomena of the dispersion particles. Well dispersion of the resin is important to the performance of the crosslinked product. According to Stokes law, separating rate of the dispersion particles, which directly affects the stability of dis- persion, is directly proportional to the density difference of oil phase and water phase, the size of the particles, and inversely proportional to the viscosity of continuous phase 25. When the density difference of oil phase and water phase and the viscosity of continuous phase are invariableness, the size of the particles can characterize the stability of waterborne dispersion. Fig. 6 shows theFig. 5. Log log y line of T-PABA and the composite dispersions.Fig. 6. Particle size distributions of T-PABA and the composite dispersions.laser particle size analysis of the T-PABA and the composite disper- sions. The HDI tripolymer used to crosslink with T-PABA cannot disperse well in water, although it has been hydrophilically modi- ed. The average particle size of the HDI tripolymer is large, about 6120 nm. T-PABA can be dispersed stably in water and does not delaminate after storing for 6 months. Its average particle size is about 40 nm. After mixing these two components completely, the composite dispersion obtained has a unimodal distribution of the particle size with the average value of about 89 nm, bigger than that of T-PABA dispersion. This result indicates that when the two components are mixed, T-PABA dispersion can emulsify the HDI tripolymer and rebuild new particles.3.4. Characterization of the composite productThe lm formation process of the composite dispersion is as fol- lows: (1) solvent, water volatilizing, (2) particles merging together,(3) isocyanate (NCO) group of HDI reacting with hydroxyl (OH) group and amine (NH) group. The results of the particles merging and the chemical reaction were characterized by AFM and FT-IR, respectively. The 3-D surface micro topography of the compos- ite product obtained from AFM is shown in Fig. 7. The surface of the product is quite rough, containing many cone-shaped hillocks. When particles of the dispersion overlap with each other, only the edge parts of the particles can merge together, and then the unmerged parts of the particles exposed on the surface of the lm are observed as cone-shaped hillocks. The “hillock topography” found on the surface of the lm is the trace of merged particles of the dispersion, which indicates indirectly that there are lots of particle traces in the body of the lm. This result validates theFig. 7. AFM image of the composite product.particle merging mechanism of the lm formation of waterborne resin 26.Urethane ( NH CO O ) and urea ( NH CO NH ) are formed after NCO group of HDI reacting with OH group and NH group of T-PABA, respectively. The chemical structure of the composite product was characterized by FT-IR spectra (Fig. 8). The signi-cation absorption peaks at about 3360 cm1 (N H stretching),1680 cm1 (C O stretching), 1536 cm1 ( NH CO stretching),and 1240 cm1 ( CO O C stretching) show the typical absorp-tions of urethane ( NH CO O ) and urea ( NH CO NH ) group27. The disappearance of the absorption peak at 2270 cm1 (NCOstretching) denotes the occurrence of addition reaction of the NCO group with active hydrogen. The other absorption peaks in the spectra assign to stretching vibration of methyl and methylene(28502990 cm1), benzene ring stretching (1605 and 1530 cm1),bending vibration of methyl and methylene (1458 cm1), isopropylgroup stretching (1370 cm1), C N stretching (1173 cm1), andC O stretching of secondary hydroxyl group (1117 cm1), respec-tively.3.5. Properties of the composite productThe properties of the composite product of T-PABA are showed in Table 2. Due to the high activity of the NH group reacting with NCO group, the lm of the composite product dried faster than the commercial product. The lm obtained from the composite prod- uct has excellent impact strength, adhesion, exibility, antifouling and blocking resistance properties. Impact strength, pencil hard- ness and water resistance of the composite product were enhanced by increasing NCO/NH (OH) ratio. Because the superuous NCO groups can react with H2O to form urea and biurea, it will increaseFig. 8. FT-IR spectra of the composite product.Table 2Properties of the composite product.ItemnNCO :nNH(OH)Crosslinked products of T-PABACommercial producta0.8:11:11.2:11.4:11.4:1Drying time (min 25 C)4045455090Gloss (60 )94.895.495.895.590.5Impact strength (kg cm)6065707050Adhesion (grade)21111Flexibility (mm)110.50.51Pencil hardnessHH2H2HHWater resistanceWater (24 h)Whitenin