纯阳离子型3D打印立体光刻快速成型光敏树脂的制备及紫外光固化性能研究

The UV-cured products of pure cationic type photosensitive resins possess small shrinkage and high precision. However, because of the poor of their photosensitivity, they are usually restricted to use alone as the photosensitive resins for 3D printing stereolithography technique. This project is intended to improve the photosensitivity of cationic type photosensitive prepolymers with siloxane groups. A series of novel siloxane-containing cycloaliphatic epoxy resins as photosensitive prepolymers are prepared. The UV-curing behavior of the cycloaliphatic epoxy resins is investigated with differential scanning photocalorimetry, constructing their UV-curing dynamics equations. The UV-curing kinetics parameters of the cycloaliphatic epoxy resins are obtained, revealing the photosensitive effect on the law of the siloxane group size. A cationic type photosensitive resin is prepared with the excellent photosensitive epoxy resin as main component which is screened from a series of siloxane-containing cycloaliphatic epoxy resins.The fabricated precision of the cationic type photosensitive resin is studied with 3D printing stereolithography apparatus. The fabricated precision of the photosensitive resin will be better than that of the current photosensitive resin in the market. The preparation of the photosensitive resin will promote the further development of the domestic and foreign 3D printing stereolithography technique to play a positive role.

纯阳离子型光敏树脂紫外光固化的固化物收缩小、制作零件精度高，但是，由于其光敏树脂预聚物的光敏性普遍欠佳，单独作为3D打印立体光刻快速成型技术的光敏树脂预聚物通常被受到限制。本申请项目拟用硅氧烷基团改善阳离子型光敏树脂预聚物的光敏性，即研究制备一系列新型含硅氧烷脂环族环氧树脂的光敏预聚物。采用差示光量热法对它们的紫外光固化行为进行研究，构建它们的紫外光固化动力学方程，以及得到它们的紫外光固化动力学参数，揭示出硅氧烷基团大小对它们的光敏性影响规律，从中筛选一种光敏性好、黏度适中的含硅氧烷脂环族环氧树脂，把它作为预聚物制备一种纯阳离子型光敏树脂。然后，应用立体光刻快速成型设备对该光敏树脂的性能进行研究。该光敏树脂制作零件的精度可望比现行光敏树脂制作零件的精度更高。该光敏树脂的研制将对推动国内、外3D打印立体光刻快速成型技术的进一步发展起到较好的积极作用。

近十年来，立体光刻3D打印的材料是环氧化合物和丙烯酸酯作为预聚物的自由基-阳离子混杂型光敏树脂，其固化收缩较纯自由基型光敏树脂固化收缩小，打印的零件精度较好。如果这种立体光刻3D打印的材料是以环氧化合物作为预聚物的纯阳离子型光敏树脂，则其紫外光固化收缩更小，制造的零件精度更好。然而，纯阳离子型光敏树脂的光敏性欠佳问题一直使业内人员感到困惑。在本项目中，我们合成了二[2-(3,4-环氧环己基)乙基]四甲基二硅氧烷，二[2-(3,4-环氧环己基)乙基]六甲基三硅氧烷和二[2-(3,4-环氧环己基)乙基]八甲基四硅氧烷,采用Photo-DSC即DPC法对这三种含硅氧烷脂环族环氧化合物的紫外光固化性能进行了研究。发现二[2-(3,4-环氧环己基)乙基]四甲基二硅氧烷的紫外光固化活化能最小。通常，光敏树脂的活化能越小，这树脂越容易进行紫外光固化反应，即树脂光敏性越好。在本项目研究中，我们选用了[2-(3,4-环氧环己基)乙基]四甲基二硅氧烷作为主要光敏预聚物制备了一种立体光刻3D打印光敏树脂。 这种光敏树脂的临界曝光量（Ec）为18.9mJ/cm2,透射深度（Dp）为0.15mm，它所打印的零件线收缩率小于0.6%和翘曲因子小于5.5%，它所打印出来的零件成型精度高和分辨率高。.本项目的科学意义在于发现了所合成的[2-(3,4-环氧环己基)乙基]四甲基二硅氧烷的紫外光固化光敏性好于市场上的脂环族环氧化合物的光敏性，这揭示了硅氧烷基团的在环氧化合物中是一个供电基团，使环氧基团更具有富电性，更易于进行阳离子型紫外光固化反应。同时，也说明了[2-(3,4-环氧环己基)乙基]四甲基二硅氧烷是一种很好的3D打印光敏树脂预聚物。