光热敏微胶囊材料的光敏特性研究
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摘要
光热敏微胶囊材料是集光敏、热敏和微胶囊材料于一体的新型数字记录复现平面媒质材料,具有高分辨率、低污染、显影方便快速等特点。
本文首先阐述了囊芯光敏物质的特性和光固化机理,介绍了光热敏微胶囊结构,并通过控制界面聚合反应参数,制备出光热敏微胶囊材料。在保证高引发固化效果的前提下,选择了合适光引发剂184、聚合单体TMPTA和TPGDA、预聚物聚氨酯丙烯酸酯7600,对各组分进行了光吸收特性的检测。并基于各材料的光谱吸收特性,对染料前体加入前后囊芯整体的光吸收及光固化效果进行了对比研究,发现染料前体的引入导致固化程度减弱；该现象可归因于ODB-2吸收峰与光引发剂有重叠,进而影响了光引发剂的光吸收效果,导致囊芯内混合物聚合固化效率降低。
为了获得较高的聚合固化效果,本文最终确定染料前体与光敏物质的质量比应在1：15～1：10内。在此比例的基础上,本文研究了囊芯物质的聚合固化过程和光热敏微胶囊的热相变特性。利用傅立叶红外光谱技术获得了囊芯物质固化前后的红外光谱变化。固化前囊芯物质在1620cm-1处存在C=C双键吸收峰,在920.1cm-1、837cm-1处存在C=C上C—H(即烯烃上的C—H键)吸收峰,而固化后囊芯物质C=C双键及烯烃上的C—H键吸收峰消失。特征峰变化表明：囊芯物质的光固化过程是TMPTA、TPGDA和7600双键打开并链增长形成立体网络结构的过程。利用差示热分析方法测量了光热敏微胶囊的囊芯、囊壁材料的玻璃点转化温度,检测结果表明：微胶囊囊壁材料在105-130℃发生玻璃态向高弹态的相变,并在130℃下相变程度达到最大,而固化囊芯材料的玻璃态相转变温度为200℃左右。囊壁和固化囊芯材料存在热相变温度差表明光热敏微胶囊材料的热显色温度应选择在130～200～C之间；在此温度范围内未曝光的光热敏微胶囊囊壁达到高弹态,胶囊外的显色物质可进入囊芯与染料前体发生显色反应,而曝光的光热敏微胶囊由于内部固化物仍处于致密的玻璃态,导致显色剂不能与染料接触显色,从而实现光信息记录。
最后,研究了光热敏微胶囊信息材料的影像密度随曝光时间、显色温度的变化关系。本文所制备的光热敏微胶囊信息材料粒径分布峰值为0.5μm,粒径分布曲线半宽度为0.15μm,扫描电镜观测表明所制备光热敏微胶囊呈规则球状。在保证光热敏微胶囊影像分辨率前提下,获得了光热敏微胶囊材料影像密度随曝光时间、显色温度的变化。影像密度曲线表明曝光后的影像密度比曝光前有所下降：在20s时降到较低值,在30s后影像密度略有上升而后再下降到最低。可根据光致体积收缩的原理解释影像密度在曝光30s时略有上升的现象。由影像密度特性表明：光热敏微胶囊材料的最佳曝光时间可选择为20s。在120℃、130℃显色温度下比较,130℃的影像密度曲线整体高于120℃,这是由于温度较高时微胶囊囊壁相变程度较大,渗透能力较强,从而导致较高显色温度下曝光与未曝光时影像密度整体提高。
The photo-heat sensitive microcapsule is a new generation panel information recording and displaying material, which integrates theory and technique of many subjects: photo-sensitive, heat-sensitive and micro-capsulation. It has a lot of advantages, such as high-resolution, low-pollution and convenient operation.
This thesis introduced the characteristics and curing mechanism of photo-sensitive materials in the core of microcapsule at first. The photo-heat sensitive microcapsule was prepared by interfacial polymerization technique with a stirring speed at 8000rps for 10min using high shear dispersing emulsifier. In order to guarantee the high efficiency of the initiator and the speed of the hardening, the optimal photo-sensitive materials were selected. The Irgacure 184 was chosen as the photoinitiator for its good yellowing resistance. Giving consideration to the diluting effect, hardening speed and rigidity, the TMPTA and TPGDA were chosen as the polymeric monomer. The polyurethane acrylate 7600 was selected as the optimal prepolymer. And these materials were detected by spectral measurement. The curing effects before and after the incorporation of dye precursor were compared, the result shows that the incorporation of dye precursor can weaken the curing effect. The spectrum overlapping of photoinitiator and dye precursor can explain the decrease in curing effect.
In order to obtain an optimal curing effect, the mass percentage of dye precursor should be in the range of 1:15～1:10. On this basis, this thesis studied the reaction process of polymerization and the thermal phase transition of the photo-heat sensitive microcapsule. According to the infrared spectrum, the absorption peak of double bond at 1620cm-1 and carbon hydrogen bond at 920.1cm-1,837cm-1 were found in spectrum before reaction. However, after the hardening these peaks disappeared. The changes illustrate the reaction process, in fact, is the process of cleavage of double bond and the formation of network structure. Differential thermal analysis instrument (DSC) was employed to measure the glass transition temperature (Tg) of both core and wall material. The glass transition temperature for wall material and hardening core were 130℃and 200℃respectively. The 70℃temperature distance suggested the optimal developing temperature should be selected between 130～200℃. When the wall is in high elastic state, the developer present outside the capsule can pass through the capsule wall and permeate into the inside of microcapsule. However, the harden core, which is still in the compact glassy state, can prevent the contact of developer and dye precursor.
At last, this paper researched the optical response property of photo-heat sensitive microcapsule. The image density under different developing temperature (120℃,130℃) was compared, and comparison shows that higher developing temperature can lead to a higher permeability and image density. In the figure, which shows the relationship between image density and exposing time, the curve reaches the first minimum, but it climbs slightly at 30s and finally get to the minimum. This trend can be explained by light-induced volume shrinkage theory. The small amount of dye precursor embedded on the surface of solid solution globe and the dye precursor resolved in polymeric monomer or prepolymer can interpret the basic image density.
本文首先阐述了囊芯光敏物质的特性和光固化机理,介绍了光热敏微胶囊结构,并通过控制界面聚合反应参数,制备出光热敏微胶囊材料。在保证高引发固化效果的前提下,选择了合适光引发剂184、聚合单体TMPTA和TPGDA、预聚物聚氨酯丙烯酸酯7600,对各组分进行了光吸收特性的检测。并基于各材料的光谱吸收特性,对染料前体加入前后囊芯整体的光吸收及光固化效果进行了对比研究,发现染料前体的引入导致固化程度减弱；该现象可归因于ODB-2吸收峰与光引发剂有重叠,进而影响了光引发剂的光吸收效果,导致囊芯内混合物聚合固化效率降低。
为了获得较高的聚合固化效果,本文最终确定染料前体与光敏物质的质量比应在1：15～1：10内。在此比例的基础上,本文研究了囊芯物质的聚合固化过程和光热敏微胶囊的热相变特性。利用傅立叶红外光谱技术获得了囊芯物质固化前后的红外光谱变化。固化前囊芯物质在1620cm-1处存在C=C双键吸收峰,在920.1cm-1、837cm-1处存在C=C上C—H(即烯烃上的C—H键)吸收峰,而固化后囊芯物质C=C双键及烯烃上的C—H键吸收峰消失。特征峰变化表明：囊芯物质的光固化过程是TMPTA、TPGDA和7600双键打开并链增长形成立体网络结构的过程。利用差示热分析方法测量了光热敏微胶囊的囊芯、囊壁材料的玻璃点转化温度,检测结果表明：微胶囊囊壁材料在105-130℃发生玻璃态向高弹态的相变,并在130℃下相变程度达到最大,而固化囊芯材料的玻璃态相转变温度为200℃左右。囊壁和固化囊芯材料存在热相变温度差表明光热敏微胶囊材料的热显色温度应选择在130～200～C之间；在此温度范围内未曝光的光热敏微胶囊囊壁达到高弹态,胶囊外的显色物质可进入囊芯与染料前体发生显色反应,而曝光的光热敏微胶囊由于内部固化物仍处于致密的玻璃态,导致显色剂不能与染料接触显色,从而实现光信息记录。
最后,研究了光热敏微胶囊信息材料的影像密度随曝光时间、显色温度的变化关系。本文所制备的光热敏微胶囊信息材料粒径分布峰值为0.5μm,粒径分布曲线半宽度为0.15μm,扫描电镜观测表明所制备光热敏微胶囊呈规则球状。在保证光热敏微胶囊影像分辨率前提下,获得了光热敏微胶囊材料影像密度随曝光时间、显色温度的变化。影像密度曲线表明曝光后的影像密度比曝光前有所下降：在20s时降到较低值,在30s后影像密度略有上升而后再下降到最低。可根据光致体积收缩的原理解释影像密度在曝光30s时略有上升的现象。由影像密度特性表明：光热敏微胶囊材料的最佳曝光时间可选择为20s。在120℃、130℃显色温度下比较,130℃的影像密度曲线整体高于120℃,这是由于温度较高时微胶囊囊壁相变程度较大,渗透能力较强,从而导致较高显色温度下曝光与未曝光时影像密度整体提高。
The photo-heat sensitive microcapsule is a new generation panel information recording and displaying material, which integrates theory and technique of many subjects: photo-sensitive, heat-sensitive and micro-capsulation. It has a lot of advantages, such as high-resolution, low-pollution and convenient operation.
This thesis introduced the characteristics and curing mechanism of photo-sensitive materials in the core of microcapsule at first. The photo-heat sensitive microcapsule was prepared by interfacial polymerization technique with a stirring speed at 8000rps for 10min using high shear dispersing emulsifier. In order to guarantee the high efficiency of the initiator and the speed of the hardening, the optimal photo-sensitive materials were selected. The Irgacure 184 was chosen as the photoinitiator for its good yellowing resistance. Giving consideration to the diluting effect, hardening speed and rigidity, the TMPTA and TPGDA were chosen as the polymeric monomer. The polyurethane acrylate 7600 was selected as the optimal prepolymer. And these materials were detected by spectral measurement. The curing effects before and after the incorporation of dye precursor were compared, the result shows that the incorporation of dye precursor can weaken the curing effect. The spectrum overlapping of photoinitiator and dye precursor can explain the decrease in curing effect.
In order to obtain an optimal curing effect, the mass percentage of dye precursor should be in the range of 1:15～1:10. On this basis, this thesis studied the reaction process of polymerization and the thermal phase transition of the photo-heat sensitive microcapsule. According to the infrared spectrum, the absorption peak of double bond at 1620cm-1 and carbon hydrogen bond at 920.1cm-1,837cm-1 were found in spectrum before reaction. However, after the hardening these peaks disappeared. The changes illustrate the reaction process, in fact, is the process of cleavage of double bond and the formation of network structure. Differential thermal analysis instrument (DSC) was employed to measure the glass transition temperature (Tg) of both core and wall material. The glass transition temperature for wall material and hardening core were 130℃and 200℃respectively. The 70℃temperature distance suggested the optimal developing temperature should be selected between 130～200℃. When the wall is in high elastic state, the developer present outside the capsule can pass through the capsule wall and permeate into the inside of microcapsule. However, the harden core, which is still in the compact glassy state, can prevent the contact of developer and dye precursor.
At last, this paper researched the optical response property of photo-heat sensitive microcapsule. The image density under different developing temperature (120℃,130℃) was compared, and comparison shows that higher developing temperature can lead to a higher permeability and image density. In the figure, which shows the relationship between image density and exposing time, the curve reaches the first minimum, but it climbs slightly at 30s and finally get to the minimum. This trend can be explained by light-induced volume shrinkage theory. The small amount of dye precursor embedded on the surface of solid solution globe and the dye precursor resolved in polymeric monomer or prepolymer can interpret the basic image density.
引文
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[3]韩金梅,赵超,李鹏.发展中的无碳复写纸[J].山东轻工业学院学报.2006.20(1)：61-66.
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[3]韩金梅,赵超,李鹏.发展中的无碳复写纸[J].山东轻工业学院学报.2006.20(1)：61-66.
[4]SANDERS, FREDERICK W. HILLENBRAND, GARY F. ARNEY, et al. Transfer imaging system [P],U.S.P 4399209,1983-8-16.
[5]Gottschalk,et alsitive materials containing ionic dye compounds as initiators[P].U.S.P 4772530, 1988-9-20
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[7]ADAIR PAUL C, BURKHOLDER AMY L. Photosensitive microcapsules useful in polychromatic imaging having radiation absorber[P], U.S. P 4576891,1986-3-18.
[8]MASASHI MIYAGAWA, TOSHIHARU INUI, KAZUHIRO NAKAJIMA, et al. Thermal Microcapsule Transfer Technology For Full-Color Printing Controlled By Photo And Thermal Energies[Z]. Hard Copy and Printing Materials, Media, and Process, Santa Clara,1990,1253:264-270.
[9]林尚安,陆耕,梁兆熙.高分子化学[M].北京：科学出版社,1987,55-80.
[10]赵红振,齐暑华,周文英等.紫外光固化涂料的研究进展[J],化学与黏合,2006,28(5)：253-256.
[11]余尚先.光固化涂料的进展[J],涂料工业,1986,(2)：34.
[12]滕蔓.紫外光固化涂料简介[J],化学教育,2003,7：6-8.
[13]朱庆红,辐射固化涂料的发展[J],中国涂料,2001(1)：36-39.
[14]Derek Eddowes. Fast Lane Finishing. Polymer Paint Colour J.,2001,191 (4442):12-14
[15]Stephen Davidson. Crowing in This Cenlurv. Polymer Paint Colour J.,2001,191(4446):30-32.
[16]王文君,邹应全.光固化涂料的应用进展[J],信息记录材料,2004,5(1)：27-30.
[17]USAMI TOSHIMASA, TANAKA TOSHIHARU, SATOMURA MASATO. Light-and heat-sensitive recording material[P], U.S.P.4529681,1985-1-16.
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