Extrusion Asia Edition 1-2019

性的阻隔涂覆及薄膜。IGB研究所高分子界面和生物材料研发 团队主管Michaela Müller博士解释说：“我们采用最新开发的 含有天然蜡和蛋白质的水基分散剂生产这些薄膜和涂层。采 用传统的涂覆技术可以加工这些分散剂。巨大的优点是膜层 可以百分之百降解，从而可以帮助减少塑料废料。这项开发 工作是IGF研究所”生物活性材料”项目的一部分。夫琅和费 IVV研究所也参与了这一项目。 复合和粘合的功能化 德国斯图加特的研究人员用特定的化学功能团对聚合物 薄膜进行改性，以改变粘结等后续工艺步骤所需的表面性 能。氨基的功能化也可以将采用气相和湿化学加工步骤生产 出的包装薄膜限制在边缘地区，并应用于复合薄膜。 通过物理杀菌得到安全食品 为了食品有更长的保存期限，包装材料必须免于被细菌 所污染。根据材料的不同，通常采用加热、气体、电离或紫 外线的方法对微生物进行灭活。IGB研究所采用低温等离子体 替代高温灭菌，这是一种对材料友好的方法。它们不仅适用 于创建膜层，而且由于等离子化过程中的反应分子和紫外线 辐射，也可使微生物失活。Barz补充道: “采用等离子杀菌， 即使是高度耐药的不同芽孢杆菌的内生孢子，在经过相对较 短的处理时间后也无法繁殖。” 此外，夫琅和费IGB研究所的科学家已经进一步开发出 了紫外线处理，以实现将外表面上可再生的微生物降到最低 的目标。采用全新设计的准分子灯或最新的紫外线发光二极 管技术，可对包装薄膜进行快速有效的消毒。这些工艺可以 在包装机器上按比例放大,以满足不同的需求。 用于高速精加工的辊涂 包装薄膜的市场对价格是极为敏感的。夫琅和费FEP研 究所致力于这方面的工作，开发出高效的精加工工艺。这种 工艺的特点是有着极高的速度。举例来说，利用等离子体活 化的高速沉积技术，以每秒几米的膜带速度生产透明的氧化 铝屏蔽层，以抵抗外部影响，如湿气或氧气对塑料薄膜的影 响。夫琅和费FEP研究所采用被称为涂布器的装置，这种涂 布器宽度可达700mm，膜材长度可达好几公里。研究人员目 前正致力于将这种已经成功的合格技术应用到生物材料上 去。另一个例子是对那些已经存在于薄膜中的高分子材料的 改性。为此目的，夫琅和费FEP研究所采用“辊到辊”的系统， sive) is used as is necessary for its function, which can lead to considerable material and cost savings. Fluorescent dyes are used as additives in the functional layer in order to measure the distribution of the layer thicknesses by measuring the fluores- cent light. The dye is added to the coating material in such small quantities that it is not visible and the material properties are not affected. By combining novel packaging materials with effective process control, scientists aim to make future food packaging safer and at the same time cheaper. Multilayer barrier layers against oxygen and water vapor The scientists at Fraunhofer IGB are also working on processes for functionalizing packaging films. In order to be able to pro- duce the widest possible range of surface properties, IGB is pur- suing the approach of functionalizing polymer films using plas- ma/CVD and wet-chemical processes – or combinations of these technologies. This creates barrier layers against the per- meation of oxygen and water vapor for outer packaging as well as barrier layers that prevent the release of polymer additives from the outer packaging into a food or pharmaceutical pro- duct. The challenge here is that the layers must be elastic to a certain extent so that they do not break or crack on the polymers. The Fraunhofer researchers therefore realize the coatings in the form of several mechanically decoupled layers, which are suc- cessively deposited “layer by layer” in the plasma. “By optimiz- ing various plasma process parameters such as the type and quantity of precursor gas used, the excitation frequency, the gas flow, the pressure and the treatment time, we can succes- sively produce glass-like layers with the desired barrier function and silicone-like elastic intermediate layers”, explains Dr. Jakob Barz, group leader for “Plasma Technology and Thin Films” at IGB. In this way, the researchers were able to increase the bar- rier effect of plastic films against water vapor and oxygen by a factor of up to 1000 compared to untreated material. The de- posited barrier layers can also be combined with another layer to improve food run-off when emptying a film package. Biobased barrier layers Currently, Fraunhofer IGB is also conducting research on bio- based layers with a barrier function against oxygen and water vapor. At ICE europe, the institute presented the first barrier coatings and films that consist of 100 percent natural starting materials and also have antioxidant or antimicrobial properties. “We produce these films and coatings from a newly developed water-based dispersion that contains natural waxes and pro- teins. The dispersion can be processed using conventional coating techniques,” explains Dr. Michaela Müller, head of the IGB research group “Polymeric Interfaces and Biomaterials”. The big advantage is that the layers are also 100 percent de- gradable and can thus help to reduce plastic waste. The deve- lopment is part of the IGF project BioActiveMaterials, in which the Fraunhofer IVV is also involved. Functionalization for lamination and adhesion The Stuttgart/Germany researchers are modifying polymer films with specific chemically functional groups in order to change surface properties that are required for subsequent process 用于阻隔氧气和水蒸汽的多层涂覆 (© Fraunhofer IGB) Multilayer coating as barrier against oxygen and water vapor (© Fraunhofer IGB) 26 正在研发中的包装薄膜 Extrusion Asia Edition 1/2019