【作者】 刘海涛；

【导师】 莫健华； 黄树槐；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2009， 博士

【摘要】 光固化三维打印技术类似于UV喷墨打印，是采用液滴喷射成形的快速成形技术。在成形过程中，使用两组喷头分别喷射光固化实体材料和光固化支撑材料，随即利用紫外光照射固化，逐层堆积成形，打印完毕后，用水枪去除支撑材料，得到需要的零件。它将喷射成形和光固化成形的优点结合在一起，提高了成形效率和精度，降低了成本。光固化三维打印需要使用实体光固化材料和支撑光固化材料来成形零件，选择恰当的成形材料至关重要。目前只有3D Systems公司和OBJET公司有光固化三维打印设备和配套成形材料，成形温度分别为100-110℃和70-75℃。本课题组是国内第一家研究光固化三维打印设备和成形材料，三维打印机使用赛尔XJ500喷头喷射光敏树脂，成形温度为50-55℃。成形温度越低，成形材料的选择面越窄，材料性能要求越苛刻，因此成形材料的制备和性能研究是一个迫切需要解决的难题。本文根据三维打印机紫外光源的特点和成形材料化学反应机理，总结了成形材料的特性参数、收缩翘曲和喷射铺展参数的实验方法。合成了聚丙二醇二缩水甘油醚二丙烯酸酯，确定最佳合成条件：以聚丙二醇二缩水甘油醚和丙烯酸为反应物，反应温度控制在100—110℃，催化剂N，N-二甲基苄胺的质量分数为0．80％，阻聚剂对甲氧基苯酚的质量分数为0．20～0．40％。以它和阳离子单体制备了一种混杂型实体材料，适合在55℃稳定喷射，光敏性好，固化后的零件具有较佳的热机性能。合成了自由基型实体材料的原料低粘度氨基甲酸酯丙烯酸酯，确定最佳合成条件：以TDI、HEA和PEG为反应物，第一步反应过程中n(TDI)：n(HEA)=1，催化剂DBT质量分数0．2％，反应温度40℃，反应时间2—3h：第二步反应过程中n(TDI)：n(PEG)=2，反应温度55—60℃，反应时间为5—6h。以它为主要原料制备了一种自由基型实体材料，适合于50℃工作，喷射稳定性、铺展性能较好，但固化收缩率大、固化速度稍慢。研究了阳离子型实体材料中苄醇促进剂的作用。苄醇通过活化单体机理和自由基诱导鎓盐光解机理加速脂环族环氧和氧杂环丁烷光固化速率，自由基诱导鎓盐光解机理起主要作用。其中苄醇上带给电子性基团，更有效地稳定了苄醚自由基和苄醚阳离子，使阳离子型光引发剂光解速率加快，从而加速阳离子体系固化速率。实验结果与理论相符。研究了阳离子型实体材料中氧杂环丁烷的光固化动力学。氧杂环丁烷首先被质子化，形成了二级氧鎓正离子，二级氧鎓正离子受另外一个单体亲核进攻而开环，相应地生成一个三级氧鎓正离子，继续不断受单体进攻形成聚合物。三级氧鎓正离子相对稳定，因此最后一步反应活化能很高，一旦克服其活化能，反应将迅速进行。以脂环族环氧、氧杂环丁烷和乙烯基醚为主要反应性原料制备了蓝色阳离子型实体材料，性能测试表明这种阳离子型实体材料喷射稳定，适合在55℃下工作，阳离子型实体材料的光敏性、固化后力学性能、热性能较佳，满足三维打印的要求。合成了三维打印支撑材料的两种齐聚物。其中水性氨基甲酸酯丙烯酸酯的最佳合成条件是：第一步在甲苯二异氰酸酯中滴加二羟甲基丙酸的反应温度为30℃，反应时间1．5小时；第二步加入聚乙二醇的反应温度为45—50℃，反应3．5h；第三步滴加丙烯酸羟乙酯的反应温度为50—55℃，反应约5h。当TDI：DMPA：PEG的投料摩尔数比为4：2：1时，得到羧基酸值约为66．5mgKOH／g的水性氨基甲酸酯丙烯酸酯齐聚物，使用三乙胺100％中和羧基后，这种齐聚物具有较好的水溶性。通过醇钠－酰氯法合成了聚乙二醇二丙烯酸酯，聚乙二醇1000二丙烯酸酯所含醚键最多，亲水性好，固化后强度低，作为另一种齐聚物。以上述两种齐聚物、β—羧乙基丙烯酸酯和温敏材料PEO—PPO—PEO配制了支撑材料。支撑材料的喷射稳定性较好，很少有堵孔现象，其光敏性较实体材料差一点。观察成形后支撑材料和阳离子型实体材料垂直结合面的SEM照片，并通过在水中浸泡和剥离性能研究表明，支撑材料较容易去除。更多还原

【Abstract】 UV-curing Three-dimensional Printing (3DP) is similar to UV ink-jet printing, whichis the spray forming of UV resin droplets. In the forming process, two sets of printingheads simultaneously spray UV-curing building material and UV-curing support material,respectively. Then the materials are cured by ultraviolet light. The materials accumulatelayer by layer. Lastly, when the printing is completed, removing the support material bywater gun, the prototyping part is achieved. UV-curing Three-dimensional Printingcombines the advantages of UV-curing and spray forming, to improve the efficiency andaccuracy of rapid prototyping and reduce costs.UV-curing building material and UV-curing support material is crucial for UV-curing3DP. At present, only 3D Systems Corporation and OBJET Corporation can supplyUV-curing Three-dimensional Printing machines and forming materials, and the sprayingtemperature of UV materials is 100-110℃and 70-75℃, respectively. It is the first teamfor us to research on UV-curing three-dimensional printing equipment and formingmaterial at home, and XAAR XJ500 is the printing head, with material sprayingtemperature of 50-55℃. The lower spraying temperature is, the less is suitable rawmaterial, and the more difficultly will we research on the forming materials. Therefore, thepreparation and properties study of UV forming materials is of vital importance.This paper researches on the theory and experimental method of the critical exposure,penetration depth, contractility, curl distortion of UV resins. Droplets formation andspraying process of piezoelectricity printing head are described, and spraying processparameters, spreading and wetting parameters are discussed. It is the theoretical principleof the preparation and properties study of UV forming materials.The polypropylene glycol diglycidylether diacrylate was synthesized bypolypropylene glycol diglycidylether and acrylic acid as two main materials. Thepreferable synthesizing conditions as below: the temperature is 100-110℃, the catalystmass fraction of N,N-dimethyl benzylamine is 0.80% and the inhibitor mass fraction ofp-hydroxyanisole is 0.20-0.40%. The hybrid building material was prepared bypolypropylene glycol diglycidylether diacrylate, cycloaliphatic epoxide, oxetane and vinylether as the main materials. The parameters and experiment results of the hybrid buildingmaterial indicated that, it has good photosensitive, and can be sprayed steadily at 55℃, the cured building material has excellent mechanical and thermal properties.The free radical building material’s oligomer of low viscosity urethane acrylate wassynthesized by TDI, HEA and PEG as three main materials. The preferable synthesizingconditions as below: at the first step, n(TDI):n(HEA)=1, the catalyst mass fraction of DBTis 0.2%, the temperature is 40℃, reaction time is 2-3 hours; at the second step,n(TDI):n(PEG)=2, the temperature is 55-60℃, reaction time is 5-6 hours. The free radicalbuilding material was prepared by low viscosity urethane acrylate as the main materials.The parameters and experiment results of the free radical building material demonstratedthat, it can be sprayed steadily at 50℃, but it’s photosensitive and contractility is poorerthan other two building materials.This paper investigates the effect of the benzyl alcohol on cationic building material.Benzyl alcohol and its analogues with electron-donating substituents are usefulaccelerators for the cationic polymerization of cycloaliphatic epoxide and oxetane. Theaccelerated nature is activated monomer mechanism and the free-radical chain-induceddecomposition of onium salt cationic photoinitiator.Oxetane is a kind of raw material in cationic building material. Thephotopolymerization kinetics of oxetane is studied by RT-FTIR technique. Throughanalyzing the photopolymerization mechanism of oxetane, it disclosed that the lastelementary reaction’s activation energy is maximum, once heat of reaction overcomeactivation energy, the reaction velocity is very fast.The blue cationic building material was prepared by cycloaliphatic epoxide, oxetaneand vinyl ether as three main materials. The parameters and experiment results of thecationic building material indicated that, it has good photosensitive, and can be sprayedsteadily at 55℃, the cured cationic building material has appropriate mechanical andthermal properties.The support material was prepared by water-borne polyurethane acrylate,polyethylene glycol (1000) diacrylate and PEO-PPO-PEO as the main materials. Thepreferable synthesizing conditions of water-borne polyurethane acrylate is as below: at thefirst step, the temperature is 30℃, reaction time is 1.5 hours; at the second step, thetemperature is 45-50℃, reaction time is 3.5 hours; at the last step, the temperature is50-55℃, reaction time is 5 hours. When TDI:DMPA:PEG is 4:2:1, acid value ofwater-borne polyurethane acrylate is 66.5 mgKOH/g, and it gain excellent water solubilitywith 100% triethylamine to neutralize. Polyethylene glycol diacrylate was synthesized by polyethylene glycol sodium with acryloyl chloride. The support material possesses goodspray stability, but the photosensitive of the support material is worse than buildingmaterials. The experiment demonstrated that UV cured support material can easily peeledby water gun.更多还原