Analysis on the key technology of the most fiery v

2022-07-31
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Key technology analysis of vapor phase antirust plastic film (Part I)

Abstract: the development history of vapor phase antirust plastic film is described, and the application forms, application fields, manufacturing methods, problems existing in the production process, technical indicators, and the current standards of the product at home and abroad are introduced

key words: vapor phase antirust plastic film vapor phase inhibitor antirust packaging plastic film key technology

I Overview: history of vapor corrosion inhibitor plastic film (vcif) is a protective inner packaging material formed by adding vapor corrosion inhibitor (VCI) or vapor phase inhibitor (VPI) to the plastic film in a certain way. The vapor phase antirust plastic film (commonly known as VCI film) is mainly prepared by chemical synthesis, screening the vapor phase inhibitor (VCI) with high temperature (200 ℃) stability and suitable vapor pressure, and mixing it with PE in the form of ultra-fine powder to prepare a plastic masterbatch with high VCI content, which is added to polyolefin resin and prepared by CO extrusion blow molding process

compared with other anti rust packaging materials, it has the characteristics of transparency, flexibility, sealing and welding, processing and forming, high barrier, beauty, convenience and economy. Its production and development history is later than that of VCI paper. The first formula for such use form was published by the United States in 1958 [1], which was not converted to industrial production at that time. A similar formula was published in Japan in 1962. It was not until 1963 that France successfully produced the first patented product named "clear Pak" film published in the United States, even for Extruded Boards (class B2) containing flame retardants. In the same year, the United States published a patent for the second formula. It was not until 1970 that patents on the manufacturing methods of such materials appeared in Japan. The formula of vcif for non-ferrous metals was first published in Britain in 1973 [2]. Later, West Germany, the former Soviet Union, Belgium, Brazil, France, Israel and other countries published patents on the formulation and manufacturing methods of such materials, with Japan and the United States being the largest. In terms of practical application, the United States has been used for a long time; Japan has been studied earlier but applied less, so far it has been rarely seen; South Korea began to contact vcif in 1993, and now it has reached the international advanced level; Southeast Asia, Taiwan and other markets are basically acting for the products of American companies

in China, Wuhan Institute of material protection began to develop vcif[3] in the 1970s, and made great achievements. After comprehensive testing, the technical indicators of the pilot products reached the then U.S. military vcif product specifications. After more than three years of industrial trial, the effect was obvious. In 1992, Zhu Yefeng applied for the patent of coated vcif [4]; In 1999, caohaichuan obtained the patent of blow molding vcif [5]; In 2000, Shenyang anti rust packaging material company proposed two new forms of vcif, expanding its application range

II. Basic principle

1 Metal corrosion mechanism

metals will spontaneously change from high-energy state to low-energy state under natural environmental conditions, that is, from unstable metal simple substance form to stable metal compound form. This change is called metal corrosion, that is, the destruction or deterioration of metals caused by chemical or electrochemical reactions under the action of environmental media, The corrosion mechanism is shown in Figure 1: the changes in the figure can be expressed by the following reaction formula:

anode: M-E → m +

cathode: O 2 + 2H 2O + 4E → 4OH -

nm + NaOH - → mm (OH) n

metals gradually become metal ions, and then form compounds to be corroded

2. Vapor phase rust prevention mechanism

in order to prevent metal corrosion, it is necessary to protect the metal. The most commonly used modern storage and rust prevention treatment method for metals and their products is the vapor phase inhibitor method. The main application form of vapor phase inhibitor is to add vapor phase inhibitor to a certain form of packaging materials to form vapor phase rust prevention packaging materials. The most commonly used is the VCI paper based on paper and paper/plastic. The VCI plastic film developed in this project is a new type of VCI packaging material with renewal significance. The basic principle of this project is to organically combine modern vapor phase inhibitor technology with plastic processing technology, so that vapor phase inhibitor can be uniformly and stably mixed in plastic film, and continuously and stably volatilize inhibitor vapor through its own characteristics - appropriate vapor pressure. This inhibitor vapor reacts with metal ions to form passive film complex Change the acid-base environment of the metal surface and form hydrophobic film on the metal surface to passivate the metal surface, so as to prevent or delay the occurrence of metal corrosion

III. thin structure form of vapor phase antirust plastic

vcif can be divided into various forms according to its structure, function and manufacturing process, and has its own characteristics and scope of application. At present, there are two types: coating type and extrusion blow molding type. The coated film is made of polyethylene, polypropylene or other plastic film as the carrier, and the adhesive, VCI and solvent are uniformly coated on the corona treated film and dried. The production method is similar to that of VCI paper. The products produced by this method have the following advantages: VCI has a wide selection range, good rust prevention effect, and is not limited by high temperature; Rapid rust prevention in early stage; The production technology is relatively simple. At the same time, there are also the following shortcomings: the problems that should be paid attention to in the quarterly protection of the external pressure testing machine: poor apparent uniformity; Poor transparency; The coating is easy to be rubbed off and adhered to the metal products or lost; The drying of solvents (such as ethanol, toluene, gasoline, etc.) consumes energy and causes certain environmental pollution. This method was fully studied as a basic method in the early stage of vcif. With the emergence of CO extrusion blow molding method, the research and application of this method will stay at a certain degree and scale. During this period, although someone carried out research on a similar method - printing vcif and obtained a patent, it was only limited to the scope of scientific research and was widely used. At present, the film produced by this method is only produced by printing in large professional manufacturers at home and abroad. Extrusion blow molding method is formed by mixing VCI directly into plastic particles and co extrusion blow molding, or by granulating VCI and co extrusion blow molding with plastic particles. Compared with coated products, it has the characteristics of high transparency, clean appearance, beautiful appearance and easy processing. It is the mainstream of vapor phase antirust plastic film. The disadvantage is that the rust prevention effect is slow in the early stage, and VCI is easy to vaporize, liquefy or deteriorate during production (155-200 ℃), which affects the screw down. 5. the adjustable distance between the screw and the connecting rod of the stroller handle: About 300mm. The spinning process and rust prevention effect, less barrier than the coating type, easy to condense, etc. With the improvement of VCI synthesis level, the expansion of its scope, the development of corresponding additives and the adjustment of its structure, the above problems will be greatly improved, and will be further studied and applied as one of the main products of antirust packaging materials in the coming decades

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