挑选温室覆盖薄膜有哪些讲究
目前国内温室主要的覆盖材料为塑料薄膜、阳光板和玻璃这三种，其中，应用最为广泛的是塑料薄膜。那么现在常用的塑料薄膜有哪
目前国内温室主要的覆盖材料为塑料薄膜、阳光板和玻璃这三种，其中，应用最为广泛的是塑料薄膜。那么现在常用的塑料薄膜有哪些种类、选择时有何要点、安装注意事项和保养技巧又分别有哪些呢？日前记者分别采访了相关的经销商和生产商，整理出他们的使用心得。
北京东方英宝国际贸易有限公司经理祖国诚告诉记者，塑料薄膜按材料分类主要包括PVC薄膜、PE薄膜和EVA薄膜等几种，其中又以PE膜为主，目前PE膜的使用量占所有塑料薄膜使用量比例的90%以上。
PE膜即聚乙烯树脂薄膜，是由聚乙烯树脂挤出吹塑而成，质地柔软、易造型、透光性好、无毒；缺点是耐候性和保温性差，不易粘接。为了适应生产要求，薄膜生产过程中常常加入耐老化剂、无滴剂、保温剂等添加剂，从而形成功能性薄膜，PE膜也不例外。普通PE棚膜中添加抗紫外线的物质，即可成为长寿膜，使用期可由原来的4至6个月延长1至2年，有的甚至可达3至5年；在普通PE膜的内侧添加阻止水滴积聚的涂层，可以有效增强防雾能力，使之具有流滴性；在普通PE膜中添加有色物质，即可形成有色膜，可以选择性透光，满足一些对生长环境有特殊要求的植物所需。
当然，调整添加物质也可以使上述几种功能同时存在于一种膜上，只是价格也会有所不同。祖国诚建议生产者在选择时还是应该综合考虑成本。他说，一般情况下，生产者在购买时首先应当选用无滴膜。结雾不仅影响透光率，积聚的水滴如果滴落在植株上还会引起植株病害，因此必须放在第一位。在此基础上再依次考虑无滴、有色等功能。另外，北方有些地区还会使用双层膜来增强保温性，这种情况下就可以选择长寿膜做外层膜，无滴膜作为内层膜。祖国诚还指出，长寿膜的长寿与否还与其他因素有关，比如地区因素。不同地区有不同的自然条件，例如西北地区，风沙大、紫外线强，因此膜老化快、寿命一般都不会太长。尽管如此，这些地区更需要使用长寿膜，不然使用普通膜损耗大，需要更换的频率会更高。
北京花木公司天卉苑研究所副所长鲍青松认为，与其他几种覆盖材料相比，塑料薄膜的使用寿命确实较短。除了因为紫外线对其分子结构的破坏以外，还与温度、摩擦等外界因素相关。在如何保养薄膜方面，他建议在日常生产中可用与膜类似的材料将与膜接触的骨架部位包裹好，这样做的好处有两个，一是减少膜与温室结构骨架之间的物理摩擦，二是可以防止金属骨架由于升温快而导致温度积聚对膜造成伤害。
谈到塑料薄膜的发展方向时，鲍青松说目前国内外越来越注重薄膜透光性的研究。实验表明，在一定范围内，强光照有增强光合作用、提高植株品质、提高产量、缩短生产周期、加快温室升温速度等好处。透光率高，光照强，植物光合作用显然会跟着增强；光照强能促使植株更紧凑，从而提高花卉品质；在透光率较高的情况下，温室内温度升高的速度也比较快。
对于新材料的应用，国内生产商的态度也是很积极的。比如备受大家肯定的F-Clean膜，因为成本高，目前在国内外都还没有大型的应用实例，也没有形成完善的温室结构应用体系，但目前天卉苑已开始与国外专业的温室公司合作开发F-Clean膜，有望在今年开始应用。
Choose greenhouse covering film which pays attention to the current domestic greenhouse covering materials are plastic film, sunshine plate and glass, of which plastic film is the most widely used. So what are the main covering materials of plastic film used in Greenhouse in our country at present? They are plastic film, sunshine plate and glass. Among them, plastic film is the most widely used. So what kinds of plastic film are commonly used now, what are the main points of selection, installation considerations and maintenance techniques? A few days ago, the reporter interviewed the relevant distributors and manufacturers, sorting out their use experience. Beijing Oriental Yingbao International Trade Co., Ltd. manager motherland sincerely told reporters that plastic film according to material classification mainly includes PVC film, PE film and EVA film, among which PE film is the main one. At present, the use of PE film accounts for more than 90% of all plastic film use. PE film is polyethylene resin film, which is extruded and blown by polyethylene resin. It has soft texture, easy to shape, good transparency and non-toxicity. Its shortcomings are poor weather resistance and thermal insulation, and it is not easy to bond. In order to meet the production requirements, additives such as anti-aging agent, drip-free agent and heat preservation agent are often added in the film production process, thus forming functional films, PE films are no exception. Adding anti-ultraviolet substances to ordinary PE greenhouse film can become long-life film, and its service life can be extended from 4 to 6 months to 1 to 2 years, or even up to 3 to 5 years. Adding anti-fogging coatings to the inside of ordinary PE film can effectively enhance the anti-fogging ability and make it dripping. Adding non-ferrous substances to ordinary PE film can form a non-ferrous film, which can selectively penetrate through. Light meets the needs of some plants that have special requirements for their growing environment. Of course, adjusting the additives can also make the above functions exist on one kind of membrane at the same time, but the price will be different. The motherland sincerely suggests that producers should consider the cost comprehensively when choosing. He said that in general, producers should first choose drip-free membranes when purchasing. Fogging not only affects the transmittance, but also causes plant diseases if water droplets accumulate on the plant, so it must be put in the first place. On this basis, the functions of non-dripping and coloring are considered in turn. In addition, in some areas of northern China, double-layer membranes are also used to enhance thermal insulation. In this case, longevity membranes can be chosen as outer membranes and non-dripping membranes as inner membranes. Motherland also pointed out that the longevity of longevity membranes is related to other factors, such as regional factors. Different regions have different natural conditions, such as Northwest China, where the wind blows and the ultraviolet radiation is strong, so the aging of the film is fast and the life of the film is generally not too long. Nevertheless, longevity membranes are more needed in these areas. Otherwise, the common membranes will lose a lot and need to be replaced more frequently. Bao Qingsong, deputy director of Tianhua Yuan Research Institute of Beijing Flower and Wood Company, believes that the service life of plastic film is indeed shorter than that of other covering materials. In addition to the destruction of its molecular structure by ultraviolet radiation, it is also related to external factors such as temperature, friction and so on. In terms of how to maintain the film, he suggested that similar materials could be used in daily production to wrap the skeleton parts in contact with the film. There are two advantages of this method. One is to reduce the physical friction between the film and the greenhouse structure skeleton, and the other is to prevent the metal skeleton from being damaged by the accumulation of temperature due to the rapid heating. When talking about the development direction of plastic film, Bao Qingsong said that at present, more and more attention has been paid to the study of transparency of plastic film at home and abroad. Experiments showed that in a certain range, strong light could enhance photosynthesis, improve plant quality, increase yield, shorten production cycle, and speed up greenhouse warming. With high transmittance and light intensity, plant photosynthesis will obviously increase; light intensity can make plants more compact, thereby improving the quality of flowers; in the case of high transmittance, the rate of temperature rise in greenhouse is faster. For the application of new materials, the attitude of domestic manufacturers is also very positive. For example, the F-Clean film, which is highly recognized by everyone, has not been applied in large scale at home and abroad because of its high cost, nor has it formed a perfect greenhouse structure application system. However, at present, Tianhuyuan has begun to cooperate with foreign professional greenhouse companies to develop F-Clean film, which is expected to be applied this year.