包装材料一、纸1、纸及其优点纸是由植物纤维缠绕或者粘结起来的的软性薄片材料。
在商业上纸一直由亚麻布、甘蔗渣、棉纤维和麦秸制造。
现代纸大多数有木材纤维制造。
作为包装材料，纸有如下一些优点：●可以根据不同等级进行生产，可制成不同的形状，尤其是纸盒或者纸箱。
●纸可以回收再利用，而且能够生物降解。
●易与其他材料层合制成复合包装材料。
●能制成具有不同透明等级的纸张。
2、纸的种类●牛皮纸牛皮纸具有较高强度，用于25 -50公斤的面粉、糖、水果和蔬菜包装。
可以漂白，印刷或未经漂白使用（棕色）。
为满足强度要求，通常使用多层牛皮纸。
●文化用纸文化用纸是由木屑和锯木厂残留物制成，这是森林产品行业的副产品。
这些材料是通过制浆和压制成薄片，从而制成文化用纸。
文化用纸用作书写纸、复印纸和打印纸。
文化用纸之所以适于上述目的是因为它有较长的纤维，且比其它纸种明亮。
●植物羊皮纸羊皮纸由硫酸盐浆制得，经过浓硫酸处理，通过膨胀和部分溶解纤维，使之塑造成型。
在纤维网中，羊皮纸关闭气孔并填补空隙，使表面比牛皮纸更完整，从而使纸张耐油，并具有更强的吸湿能力。
用来包装黄油、奶酪和新鲜的鱼或肉。
●防油纸防油纸由亚硫酸盐纸浆制成，亚硫酸盐纸浆中的纤维被捣碎得更彻底以生成更紧密的结构。
它可耐油脂，尽管遇湿时耐油性丧失，但它广泛用于鱼、肉和乳制品的包装。
●薄玻璃纸玻璃纸与防油纸类似，但由于更多得被压制，从而密度增大，产生一个紧密的结构和高光泽面。
干燥时更能防水，一旦遇水则不失去防水性能。
●涂布纸许多纸张是由蜡涂、干蜡（蜡趁热时渗透到其中）或上蜡（其中蜡是在纸浆的准备时加入）处理的。
蜡提供保湿屏障，并允许纸张被加热密封。
然而，简单的蜡涂层很容易因折叠或研磨食品而破损，但这可通过纸层之间涂蜡和/或聚乙烯蜡层克服。
涂蜡纸用于面包包装和谷类食品纸箱包装的内衬。
二、纸板“纸”和“纸板”是不确定的术语，这与材料测量（厚度）有关，或者与材料的定量（重量）有关。
国际标准化组织（ISO）规定: 重量每平方米超过250克（每1000平方英尺51磅）材料，应称之为纸板。
美国则是称超过300微米（0.012英寸）的纸板为纸。
●纤维板纤维板（厚度超过0.11毫米）是实心的或波纹状的。
实心类型的纤维板外层是牛皮纸，内层是漂白的纸板。
它具有抗压缩性能，并受较小程度的影响。
小纤维板采用单层板，带或不带箔层和低密度聚乙烯内层。
●瓦楞纸板瓦楞纸板具有波纹内层，夹在挂面层之间。
用于制造容器以运输产品至工厂、仓库、零售商店、办公室和家庭。
用瓦楞纸板运输这些产品非常不错，因为它重量轻，结实，并且容易为所有产品定制适宜的尺寸。
楞型描述了波浪形的纸板材料的结构，而这种材料构成了纸板的瓦楞。
▶A型楞A型楞，是原始的楞型，楞高是最高的，因此，与内外原纸粘合后，厚度最大。
A型楞最适于易碎的、脆弱物品的缓冲及堆码。
▶B型楞B型楞，瓦楞纸业所采用的第二种楞型，每英寸有较低的尺寸高度和更多的瓦楞。
这意味着，中等接触和支持更多点的衬垫，提供了硬度、高品质印刷和模切的平整平面与良好的抗压性能。
▶C型楞C型楞介于A型楞与B型楞之间，并为食品提供缓冲、堆码和印刷性能。
C型楞是目前使用最广泛的楞型。
据估计，今天80％的瓦楞纸箱是由C型楞纸板制作。
▶E型楞E型楞纸板楞数最多，这使得其具有最大的抗压性能和最平坦的表面以获得高品质的印刷性能。
E型楞的薄纸板（C型楞厚度的四分之一）减少纸盒的大小，节省存储空间。
由于它的超薄和优良的缓冲性能，E型楞常常可以取代传统折叠纸箱或容器。
现在，在瓦楞纸行业，一种新的楞型，F型楞，是最新的增长点。
最初在欧洲发展的新瓦楞背后的想法，是制作含较少纤维的包装。
F型楞可以减少包装中纤维的总量，从而制得更坚挺的纸盒，而有更少的固体废弃物埋入填埋场。
一般而言，较大的楞型提供更大的强度和缓冲，而较小的楞型有较好的印刷适性和折叠性。
在同一块纸板内，不同的楞型可以被混合并相结合，以改变印刷适性、压缩强度、缓冲性能和纸板的总厚度。
例如，C型楞和E型楞组合的瓦楞纸板，既有C型楞的压缩性，又有E型楞纸板的光滑印刷表面。
●箱纸板箱纸板是多层硬质纸材，用于制作各种颜色、形状和大小的盒子，包括谷物、鞋、糖果箱。
箱纸板通常有六至八层。
上层往往是由整齐的纸浆或其他优质再生纸制成。
内层均采用低质量的纸张制成。
三、塑料塑料是由有机大分子组成的有机材料。
塑料材料可通过一系列的工艺成型，如挤出、成型、挤压或旋转。
现代塑料（或聚合物）拥有许多极为理想的特征：高强度重量比，优良的性能，电绝缘，耐酸、碱和溶剂。
●聚乙烯（PE）聚乙烯树脂的机械性能变化范围很宽，但耐化学性相对统一。
化学方程式遵循一定的模式。
分子可能分支或直接导向直链。
高度分支的材料更加灵活。
不同种类聚乙烯的物理性能，包括LDPE、LLDPE和HDPE，使之成为具有多功能的食品包装材料。
需要注意的是聚乙烯的化学性质，包括聚乙烯塑料生产中应用的单体和联合体、商业过程，聚乙烯生产中使用的添加剂，并在正常使用情况下从PE膜到食物的物质的迁移。
由于其多功能的特性，易于制造和转化及相对低的成本，PE已经达到了其主导地位。
●聚丙烯（PP）单向拉伸聚丙烯（OPP）是光泽性良好的薄膜，具有优良的光学特性，较高的抗拉强度和抗穿刺性。
对水分、气体和异味具有适中的透过性，，且不受湿度变化的影响。
它是热塑性塑料因此可以延伸，尽管较少于PE，具有低摩擦性，这最大限度地减少了静电积聚，并使其适合高速灌装设备。
双向拉伸聚丙烯（BOPP）也有类似于OPP的性质，但强度更大。
PP和OPP用于瓶、罐、薯片、饼干包装和许多其他应用的蒸煮袋包装膜。
●聚偏二氯乙烯（PVDC）PVDC具有优异的氧气和水分阻隔性能，近年来包装对此材料的需求急剧增加，它拥有乙烯-乙烯醇共聚物（EVOH）所不及的许多优点，水分不会影响PVDC的透氧率。
聚偏二氯乙烯的成本高往往意味着它现在只用作涂层和吸塑包装。
对PVDC使用增长的主要威胁来自环保游说，其中提出：在食品接触应用中，由于PVC和PVDC产品可能有致癌物迁移，这引起了人们关于PVDC的使用的关注。
●聚对苯二甲酸乙二醇酯（PET）PET是一种高强度的透明薄膜，具有良好的光泽性和水分阻隔性能。
在70℃至135℃的温度范围内均可，温度或湿度的变化能引起微小收缩。
Packaging Materials1Paper1.1 Paper and its advantagesPaper is defined as a matted or felted sheet usually composed of plant fiber. Paper has been commercially from such sources as rags (linen), bagasses (sugar cane), cotton and straw. Modern paper is made almost exclusively from cellulose fiber derived from wood.Paper has a number of advantages as a packaging material：●It is produced in many grades and converted to many differentforms, especially boxes or cartons.●It is recyclable and biodegradable.●It is easily combined with other materials to make or laminatedpacks.●It can be produced with different degrees of opacity.1.2 Types of papers●Craft paperCraft paper is a strong paper which is used for 25—50kg multi-wall sacks for powders, flour, sugar, fruits, and vegetables. It can be bleached white, printed or used unbleached (brown). It is usually used in several layers or plies to give the required strength.●Fine paperFine paper is made from woodchips and sawmills residues, which is a by-product of the forest product industry. These materials are pulped and pressed into sheets to make fine paper. Fine paper is used as writing paper, photocopier paper and printer paper. Fine paper is good to use for these purposes because it has longer fibers and is brighter than other paper grades.●Vegetable parchmentVegetable parchment is produced from sulphate pulp which is passed through a bath of concentrated sulphuric acid to swell and partly dissolve the fibres, to make them plasticized. This closes the pores and fills voids in the fibre network to make the surface more intact than Kraft paper andthus makes the paper resistant to grease and oils and gives greater wet strength properties. It is used to pack butter, cheese and fresh fish or meat.●Greaseproof paperGreaseproof paper is made from sulphite pulp in which the fibres are more thoroughly beaten to produce a closer structure. It is resistant to oils and fats, and although this property is lost when the paper becomes wet, it is widely used for wrapping fish, meat and dairy products.●GlassineGlassine is similar to greaseproof paper, but is given additional calendaring to increase the density and produce a close-knit structure and a high gloss finish. It is more resistant to water when dry but loses the resistance once it becomes wet.●Coated paperMany papers are treated with wax by coating, dry waxing (in which wax penetrates the paper while hot) or wax sizing (in which the wax is added during the preparation of the pulp). Wax provides a moisture barrier and allows the paper to be heat sealed. However, a simple wax coating is easily damaged by folding or by abrasive foods, but this is overcomed by laminating the wax between layers of paper and/or polyethylene. Waxed papers are used for bread wrappers and inner liners for cereal cartons.2Paperboard“Paper” and “paperboard” are nonspecific terms that can be related to either material caliper (thickness) or grammage (weight). The International Standards Organization (ISO) states that material weighing more than 250 grams per square meter (51 pounds per 1000 square feet) shall be known as paperboard. U. S. practice calls paper that is more than 300 micrometers (0.012in.) thick paperboard.●FiberboardFiberboard (more than 0.11mm thick) is either solid or corrugated. The solid type has an outer Kraft layer and an inner bleached bard. It is able to resist compression and to a lesser extent impact. Small fiberboardcylinders are made using single ply board, either with or without a foil layer and LDPE inner layer.●Corrugated cardboardCorrugated cardboard has a corrugated (wavy) inside layer, sandwiched between layers of linerboard. It is used to make containers for shipping products to factories, warehouses, retail stores, offices and homes. It is good to use corrugated card-board for transporting these products because it is light, strong and easily custom-sized for all products.The “flute”describes the structure of the wave shaped cardboard material that makes up a board’s corrugation.▶A-fluteA-flute, the original flute, is the highest flute size, and therefore, when combined with an inner and outer facing, is the thickest. A-flute makes the most of corrugator’s cushioning and stacking properties for fragile and delicate items.▶B-fluteB-flute, the second flute size adopted by the corrugated industry, has lower arch heights and more flutes per foot. This means that the medium contacts and supports the liners at a greater number of points, providing a stiff, flat surface for high quality printing and die cutting and with excellent crush resistant properties.▶C-fluteC-flute came along net to split the difference between A and B , and offers food cushioning, stacking and printing properties. C-flute is by far the most widely used flute size. An estimated 80﹪of today’s corrugated containers are made of C-flute board.▶E-fluteE-flute has the greatest number of flutes, which gives it the greatest crush resistance and the flattest surface for high quality printing applications. The thin board profile of E-flute (It is one-fourth the thickness of C-flute) reduces box size and saves storage space. Because of its thin profile and excellent cushioning properties, E-flute can often substitute for conventional folding cartons or solid fiber containers.Today, F-flute, a new flute, is the newest growth segment in the corrugated industry. The idea behind the new flute, originally developed in Europe, is to make packages with lower fiber content. With F-flute, converters can reduce the total amount of fiber in the packaging, thereby creating a more rigid box with less solid waste going into landfills.Generally, larger flutes provide greater strength and cushioning, while smaller flutes have better printability and foldability. Flute profiles can be mixed and matched within the same piece of combined board, to manipulate printability, compression strengths, cushioning strengths and the total thickness of the board. For instance, CE double wall gets its durability from its C-flute layer, while the E-flute gives it a smoother printing surface.●BoxboardBoxboard is a multi-layer rigid paper material that is used to make boxes of various colors, shapes and sizes, including cereal, shoes and candy boxes. Boxboard usually has from six to eight layers. The upper layer is often made from a dinked pulp or other high quality recovered paper. Inner layers are made with a lower-quality paper stock.3PlasticsPlastics are organic polymeric materials consisting of giant organic molecule. Plastic materials can be fond into shapes by one of a variety of process, such as extrusion, molding, ousting or spinning. Modem plastic (or polymers) possesses a number of extremely desirable characteristics: high strength to weight ratio, excellent properties, electrical insulation, resistance to acids, alkalis and solvents.●Polyethylene(PE)PE resins vary widely in mechanical properties but are relatively uniform in chemical resistance. Chemical formulation follows the pattern. Molecules may be branched or directionally oriented straight line. Highly branched materials are the more flexible.The physical properties of the different types of PE, including LDPE, LLDPE and HDPE, make it a versatile material for food packaging.Particular attention is paid to the chemistry of PE, including the monomers and co monomers used in PE plastics manufacture, commercial process used in PE manufacture, additives used in PE production, and the migration of substances from the PE film into the food under normal conditions of use. PE has achieved its dominant position due to its versatile properties, ease of manufacture and conversion and relatively low cost.●Polypropylene (PP)Oriented polypropylene (OPP) is a clear glossy film with good optical properties and a high tensile strength and puncture resistance. It has moderate permeability to moisture, gases and odors, which is not affected by changes in humidity. It is thermoplastic and therefore stretches, although less PE, and has low friction, which minimizes static buildup and makes it suitable foe high-speed filling equipment.Biaxial oriented polypropylene (BOPP) has similar properties to OPP but is much stronger. PP and OPP are used for bottles, jars, crisp packets, biscuit wrappers and boil-in-bag film among many other applications.●Polyvinyl dine chloride (PVDC)The excellent oxygen and moisture barrier properties of PVDC has created a sharp increase in demand for this material by packaging converters in recent years, where it has considerable advantages over ethylene vinyl alcohol (EVOH) as moisture does not influence the oxygen transmission rate of PVDC . The high cost of PVDC tends to mean that it is used in the form of copolymers and as coatings or blister packaging. The main threat to the growth of PVDC use comes from the environmental lobby, where concern has raised regarding its use in food contact applications due to the possible migration of carcinogens and endocrine disrupters from PVC and PVDC products.●Polyethylene terephthalate (PET)PET is a very strong transparent glossy film which has good moisture and barrier properties. It is flexible at temperatures from 70℃to 135℃and undergoes little shrinkage with variations in temperature or humidity.。
