QUANTITATIVE EVALUATION OF ADHESION STRENGTH OF INK DEPOSITED ON PLASTIC FILMS WITH A NANO INDENTER AND A SCANNING PROBE MICROSCOPE

As our lifestyles change, the convenience food industry booms. Many convenience food products use flexible, boilable, and microwavable plastic packaging. Almost every package is printed with ink, promoting what is inside the package, listing ingredients and nutrition data, giving preparation instructions, etc. The adhesion of ink on plastic films merits increasing attention to ensure quality packaging. However, this property has not been systematically studied and lacks a scientific method to measure the adhesion strength quantitatively. We are developing a technique of using a Nano-Indenter and a Scanning Probe Microscope to evaluate the adhesion strength of ink deposited on plastic films. It shows promise, and the measurement will be helpful in better understanding the adhesion mechanism, thus giving direction as to how to improve the adhesion.     

Analysis of Gravure Ink: Its Adhesion Strength and Thermo-elastic Behavior

In the packaging industry, the use of gravure ink has a major influence on the product contained in the package in terms of protection and communication. Another purpose of the film of gravure ink is to prevent heat transfer either from outside or from inside of the container or pack. However, the adherent film is not always long lasting. In this work, the mechanical and thermal properties of gravure ink films were measured. The mechanical properties measured, included the density, modulus of elasticity and the Poisson's ratio. The thermal measurements were confined to thermal conductivity, specific heat, heat diffusivity and the coefficient of linear expansion. If taken into account, these findings may be helpful in applying these films for the better protection of packaged products and in improving the adhesion of the films to different metallic and non-metallic substrates.     

塑料薄膜对食品安全的影响及控制措施

阐述了我国塑料食品包装薄膜的发展现状及对食品安全的影响的潜在因素。重点分析了目前我国现有的塑料食品包装薄膜的相关检测标准、检测方法及限量要求,并阐述了塑料食品包装薄膜中各类添加剂对食品卫生性能的影响,最后指出塑料食品包装薄膜对食品安全影响的控制措施。通过总结归纳目前我国塑料食品包装薄膜的发展趋势,为进一步规范塑料食品包装薄膜市场,保障食品安全提供指导。     

欧洲食品包装材料法规目前的动态

介绍了欧盟与食品包装材料有关的法规结构和其中几个重要法规的目前动态,重点在用于塑料、涂料、印刷油墨等食品包装材料中的添加剂和颜料的相关法规。     

吸氧塑料包装的研究进展

概述了近年来国内外用于食品包装的吸氧塑料的研究进展,展望了吸氧塑料的发展前景,其中单层吸氧塑料是最有发展潜力的包装材料,提出未来吸氧塑料的研究重点是其配方设计、安全可靠性、产品成本的降低及其可循环利用性。     

The Effects of Accelerated Aging and Contact with Food Simulants on the Adhesion of Amorphous Hydrogenated Carbon Films Deposited on Clarified Polypropylene

This work focuses mainly on the influence of time, temperature, and contact with food simulants on the adhesion of amorphous hydrogenated carbon (a-C:H) films obtained by plasma-enhanced chemical vapor deposition (PECVD) in clarified polypropylene (cPP). Two types of films prepared by PECVD were studied: diamond-like carbon (DLC) and polymer-like carbon (PLC) films that can both act as a functional barrier. The adhesion between the film and polymer substrates is critical in relation to the barrier effectiveness during the packaging shelf life. Therefore, the adhesion was analyzed by a tape test and scanning electron microscopy (SEM). The films were exposed to Food and Drug Administration (FDA) listed food simulants and were submitted to an accelerated aging test to evaluate the long-term adhesion performance of a-C:H films. The chemical alterations on the surface related to the accelerated aging test and the liquid simulants were analyzed by a contact angle test. It showed that the polarity of a-C:H films increased after immersion in liquid simulants, indicating a change on the surface. Before the accelerated aging test, the SEM micrographs and the tape test indicated that the PLC film has a structure with lower surface tension and, therefore, regions with fewer detachment points in relation to the DLC film. The results obtained in this study showed that the adhesion behavior and preservation of the a-C:H structure (DLC or PLC) are related to intrinsic factors such as the type of film structure (flexible or rigid) and the polymeric substrate.     

A comparative study of the interaction between the dried ink layer and PLA film used for packaging purposes

This research aims at comparing the interactions between the water-based printing ink and polylactide (PLA) printing base. As a reference base, a polyethylene terephthalate (PET) film was chosen. The wettability of both films was investigated. The Owens–Wendt method was applied to calculate the surface free energy (SFE). The values of SFE and its polar and dispersive components were compared with the surface tension (ST) of the ink and the polar and dispersive components of ST. The wetting envelopes of the investigated PLA and PET films are presented. Finally, the bonding strength between the dried ink layer and the printing base was analyzed. The PET film exhibited higher values of SFE. However, the bonding strength between the dried ink layer and the printing base was higher for PLA films. Our results reveal that PLA films can be an excellent choice as packaging materials, with comparable or even better print quality than conventional fossil-based plastics.     

Thin wall injection-overmoulding of polyamide 6/polypropylene multilayer parts: PA6/PP-g-ma interfacial adhesion investigations

This work investigates the interfacial adhesion of PA6/PP-g-MA in a thin-walled multilayer part obtained by injection overmoulding. This process is a good solution to the need of weight reduction for the sustainable and economic growth of food packaging. A rigid plastic food package is a complex multilayer structure obtained from the association of polymers with different properties to achieve good barrier, environment, or thermo-mechanical performance. The present study aims to obtain a complete understanding of the interfacial adhesion of PA6/PP-g-MA interface in a three-layer PA6/sealant/PP assembly through microscopy analysis, mechanical characterization, and inter-diffusion models. Optical microscopy, XPS, and AFM analyses showed the presence of a copolymer interphase. This layer is greatly dependent on the holding pressure applied, which revealed to be the key parameter to obtain the best results in terms of failure strength. A better interface wettability improves the inter-diffusion distance and thus chemical grafting efficiency. Other interface improvements were achieved by the addition of EVA in the PP-g-MA layer. The lowest viscosity of the EVA dispersed phase has led to a fully cohesive failure due to an interface diffusion efficiency. The presence of EVA increased more than 80% of the peeling performance of the assemblies.     

酯溶型聚氨酯的合成研究

甲苯型聚氨酯由于其残存的溶剂会随着包装渗透至食品里,因此,尽快寻找一种新型的油墨来代替已经迫在眉捷。水性聚氨酯虽然以水为溶剂,但是其性能还远远不能达到实际生产的要求,目前,很多工作者都在研究以乙酸乙酯来代替甲苯,制备酯溶型聚氨酯。很多文献均以单种聚酯二元醇来原料来制备聚氨酯,但是性能对于塑料包装欠佳,因此,文章以分子量为500的二元醇pol-1和分子量为2000的二元醇pol-2制备了酯溶性聚氨酯,并利用红外光谱对聚氨酯进行了定性表征。由测定T-型剥离强度结果可知,当pol-1与pol-2的质量比为1∶3时最好。     

A Method for Measuring the Adhesion Strength of Powder Coatings

A method for testing and quantifying the adhesion strength of particulate coatings was developed. A gas impingement test was developed to measure adhesion forces of electrophoretically-deposited layers of phosphor particles for use as information display screens. A high pressure jet of nitrogen gas is directed perpendicularly to a particulate deposit. The particles are removed from the substrate in a ring pattern which can be correlated to the skin friction on the substrate, giving a measurement of adhesion strength in the range of 100 to 450 Pa.     

SYNTHESIS AND CHARACTERIZATION OF A NEW ACRYLIC ADHESIVE MIXTURE FOR USE IN OCULAR STRABISMUS SURGERY

A new series of acrylic adhesive mixtures was specifically designed for use in strabismus surgery, more precisely to join the rectus muscles to the sclera. These two-part adhesives consisted of a mixture of ethyl cyanoacrylate (CN) and ethyl carboxyacrylate (ECA). ECA acted as a plasticizer imparting flexibility to the CN, and also as a nonreactive diluent, serving to reduce the exotherm in the reaction between CN and eye tissues. In this article, the synthesis of the ethyl carboxyacrylate is described, and the properties of different ethyl cyanoacrylate + ethyl carboxyacrylate mixtures were studied. The curing reaction of the adhesive mixtures was monitored using Fourier transform infrared (FTIR) spectroscopy and scanning differential calorimetry (DSC). The rheological properties of the cured CN-ECA adhesive films were studied using plate-plate rheometer experiments. To quantify the adhesion, single lap-shear tests produced between a rubber and the adhesive mixtures were performed and, to evaluate the adhesion to eye tissues, tensile strength measurements of superior rectus muscle/adhesive mixture/sclera joints were carried out. The 70CN-30ECA (v/v) adhesive mixture provided the most adequate balance between adhesion and mechanical properties in the joining of the superior rectus muscle to the sclera. The glass transition temperature of the CN-ECA adhesive mixtures linearly decreased with increase in the ECA content, and a lower degree of conversion during polymerization was obtained by increasing the ECA content. As a consequence, the CN-ECA mixtures were less stiff than CN, giving better performance in the joining of the rectus muscles to the sclera. Finally, the adhesion of CN was sufficiently decreased in CN-ECA mixtures, and the locus of failure was directed to the adhesive film in the joint between the rectus muscles and the sclera.     

Calorimetric Measurements of The Heat Generated by The Peel Adhesion Test

The peel test is a simple mechanical test commonly used to measure the adhesion of flexible films bonded to rigid substrates. When the film is deformed elastically during peeling, the peel force is a direct measure of the strength of the interface. However, when plastic deformation takes place, the work of detachment is much larger than the thermodynamic work of forming the fracture surfaces. Simultaneous mechanical and calorimetric measurements of the work of detachment and the heat generated during the peeling of polymeric films from metal substrates and metal films from polymeric substrates have been made. An energy balance for peeling has been proposed. Most of the work of peeling was consumed by plastic deformation. The peeled polymer dissipated approximately one half of the work of peeling as heat and most of the remainder was stored in the peeled material. The peeled metal dissipated most of the work of peeling as heat.     

Development of extrusion blown films of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) blends for flexible packaging

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a biodegradable polymer with significant potential for use in food packaging. However, its limited melt strength poses a challenge when employing film-blowing techniques to produce flexible packaging. To overcome this obstacle, we developed blends consisting of 70 wt% PHBV and 30 wt% poly(butylene-co-succinate-co-adipate) (PBSA). Organic peroxides such as dicumyl peroxide and 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, were utilized as reactive compatibilizers to enhance the interfacial adhesion between the polymers. Additionally, acetyl tributyl citrate (ATBC) was employed as a plasticizer to improve processability and ductility. The inclusion of organic peroxides resulted in the formation of long-branched structures, as confirmed by the van-Gurp-Palmen plot. The melt flow index decreased from 30 to 9.8 g/10 min without ATBC and 15.5 g/10 min with ATBC. Successful production of blown PHBV/PBSA films was achieved on a pilot scale (bubble height 180 cm). These films exhibited heat-sealing capability and increased impact strength (7.7 kJ/m²). Moreover, the films maintained a maximum elongation at break of 4% during a 3-month storage experiment with frozen food. Food safety was assessed through overall migration experiments, and the non-plasticized films received approval. In conclusion, the compatibilized PHBV/PBSA blends demonstrate great potential as materials for manufacturing film-blown flexible packaging.     

Effect of poly(vinylidene fluoride) binder crystallinity and graphite structure on the mechanical strength of the composite anode in a lithium ion battery

We have evaluated the mechanical strength of a series of composites consisting of carbon particles bound together by poly(vinylidene fluoride) (PVDF), which is closely related to the carbonaceous anode in a lithium ion battery. We used a balanced beam scrape adhesion tester and evaluated the influence of carbon particle structure, the chemical properties of PVDF, and the processing parameters of annealing temperature and casting solvent on the adhesion of the composite film to a copper substrate. The composite prepared with amorphous carbon shows over 10 times higher adhesion strength than those fabricated from other graphite materials. This results from chemical binding that is intermediate between semi-ionic and covalent C-F bonds, as detected by X-ray photoelectron spectroscopy. To address the effect of the crystalline phase of the binder on the adhesion strength, we investigated PVDF crystallinity in the composite films using differential scanning calorimetry. Samples with higher crystallinity show higher adhesion strength, independent of annealing temperature and casting solvent. The scratch adhesion was also measured for swollen electrodes immersed in 3:7 volume ratio of ethylene carbonate:ethyl methyl carbonate (EC:EMC) at different temperatures. After being swollen, the composite films prepared from PVDF modified with hydroxyl functional groups show higher adhesion strengths than the others due to their low uptake of the electrolyte solvent.     

Development of catechol-functionalized chitosan/poly(vinyl alcohol) nanocomposite films incorporated with dual network coated layered clay for active packaging applications

In order to solve the problems of traditional plastic packaging materials like poor degradability and insufficient active packaging function, this study successfully designs and synthesizes tannic acid (TA)-titanium (Ti) dual network coated hydrotalcite-like layered clay (LDHs@TA-Ti) and catechol grafted chitosan (C-CS) based on the principle of mussel bionics. And a novel idea is first put forward to fabricate LDHs@TA-Ti/C-CS/polyvinyl alcohol (PVA) nanocomposite films by solution casting method. The result of infrared and thermal analysis indicate that strong interfacial interaction is formed in the nanocomposites, which leads to the limitation of molecular chain movement and the increase of glass transition temperature. Although the addition of LDHs@TA-Ti significantly increases the crystallization temperature, the crystallinity does not change significantly. The water resistance, UV barrier, tensile strength and antibacterial properties of the final nanocomposite films are improved significantly, and all the films show good transparency in the visible range. Especially when the addition amount of LDHs@TA-Ti reaches 1 wt%, compared with C-CS/PVA composite film, the UV (at 300 nm) barrier property and tensile strength are increased by 36.3% and 45.1% respectively. Therefore, LDHs@TA-Ti/C-CS/PVA nanocomposite films show great potential as environmentally friendly active packaging films or coatings in extending the shelf life of food products.     

Scratch behavior of extrusion and adhesive laminated multilayer food packaging films

Scratch‐induced puncture damages on adhesive and extrusion laminated multilayer food packaging films were investigated. Films were tested using a modified standardized linearly increasing load scratch test methodology, ASTM D7027‐05/ISO 19252:2008, which has successfully demonstrated an ability to correlate damages observed in field use of packaging films to laboratory findings. Samples were cross‐sectioned to view the evolution of damage in a layer‐by‐layer fashion to determine any potential weak‐link in the laminate. It was observed that the extrusion laminated film showed both superior scratch performance and superior layer adhesion with increasing scratch load, particularly upon severe film deformation. The extrusion lamination process may be used to produce strong, scratch‐resistant packaging films without the need for additional adhesive layers and the associated health and environmental concerns. Usefulness of the standardized scratch testing for evaluating performance of food packaging films and laminates is discussed. POLYM. ENG. SCI., 54:71–77, 2014. © 2013 Society of Plastics Engineers     

塑料软包装薄膜的印刷技术及环保措施

介绍了塑料软包装薄膜的印刷和复合工艺,从油墨、塑料原料及废弃物处理等方面阐述了塑料软包装薄膜印刷工业中采取的环保措施并,指出了塑料软包装薄膜印刷工业的发展方向。     

食品用塑料包装材料的安全性研究

针对常用的塑料包装材料及特性、食品用塑料包装材料主要安全问题、有关塑料包装材料检测标准和方法,分析塑料包装材料对食品安全的影响。     

聚烯烃液体包装专用料的研制

采用优选法试验制得的聚烯烃液体包装专用料,是由LDPE、HDPE、LLDPE、NPA型加工助剂共混配制成的高强度液体包装专用料。经吹塑制成液体包装膜后,可用于牛奶等液体的包装,具有破损率低、实际应用好等特点。这种液体包装专用料也可以代替LDPE重包装料制成重包装袋,用于包装各类材料。     

Polyolefin properties for rigid food packaging

Polyolefins are used in many rigid plastic packages that are developed for food applications. Generally, the polyolefins used are selected for a balance of cost, ease of molding, and performance properties in a finished package. In this paper some of the physical and sorption properties of polyolefins that are critical to rigid plastic packages are discussed. Initially, a brief review of the performance requirements of plastic food packages will be presented. This is followed by discussions of specific properties of polyolefins such as impact resistance, adhesion and thermal resistance, and how they may be enhanced by coextrusion. Additionally, the sorption of food components such as flavors into polyolefin walls of packages is discussed. Here, the applicable theoretical considerations for sorption and their value for analyzing experimental data are presented. Finally, specific sorption properties of d-limonene in ethylene-propylene copolymers and their effects on package performance and design are reported and discussed.