Overview of the hottest composite packaging materi

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Overview of composite packaging materials (1)

1. What is composite packaging materials

1 meaning

the so-called composite materials are materials composed of two or more substances with different properties; The composite packaging material is a kind of more practical and complete packaging material, which follows the combination of strengths and weaknesses in the microstructure, gives full play to the advantages of the materials, expands the scope of use, improves economic benefits, and makes it a more practical and complete packaging material. Therefore, the performance of composite packaging materials is much better than that of any single traditional packaging materials

common composite packaging materials include cellophane/plastic, paper/plastic, plastic/plastic, paper/metal foil, plastic/metal foil, cellophane/plastic/metal foil, etc. In addition, there are dry paper/plastic, dry paper/plastic/other materials, etc. that can be used to carefully measure the sensor feedback value

however, any composite packaging material cannot be perfect due to the limitations of the technical environment at that time. Various problems may occur in the application process, so it is natural to make corresponding improvements. Therefore, composite packaging materials have a "dynamic" meaning, not unchanging. For example, when the packaging of cellophane/polyethylene (PE) contains salt, grease and other contents, the affinity between cellophane and polyethylene is easy to deteriorate due to the penetration to its interface, resulting in interlayer peeling, which affects the packaging. Therefore, the performance of cellophane/pe coated with polyvinylidene chloride (PVDC) is used to improve its performance, and the obtained cellophane/pvdc/pe can avoid interlayer peeling

2 challenge

the "four big" traditional packaging materials (paper, plastic, glass and metal) in the packaging industry have been used all the time. On the other hand, due to the influence of many factors, they are facing the challenge of new packaging materials, and the field of single application is shrinking day by day. According to the relevant information provided by American packaging agencies, the development trend of packaging in the next 10 years is predicted, which mainly includes: (1) light weight, aseptic and green packaging will become the mainstream and symbol of modern packaging; (2) Glass, metal and other large container packaging will gradually withdraw from some markets; (3) Ultra thin plastic packaging (white pollution) must be banned; (4) Strive to reduce the manufacturing and transportation costs of packaging. When the temperature reaches the set temperature, take the road of diversified packaging; (5) The small amount and quantitative flexible packaging welcomed by consumers will continue to develop; (6) Anti theft and anti-counterfeiting safety packaging will be further emphasized; (7) The advantages of composite packaging materials are more prominent, which will replace the traditional packaging materials, and so on

under the situation of global economic downturn, sales depression and rampant disasters, how to get out of the plight of the packaging industry is of concern. Looking at the trend of

, composite packaging materials are obviously a subject worthy of attention. However, in terms of capital, talents and equipment, there are still many difficulties. Only by overcoming the difficulties can we make progress, expand the application scope of composite packaging materials, improve their influence and play their positive role

3 discussion

because there are many kinds of raw materials involved in composite packaging materials with different properties, which materials can be combined, or can not be combined, and what is used for bonding, there are many and complex problems, so they must be carefully selected in order to obtain the ideal effect. The selection principles are as follows: (1) specify the object and requirements of packaging; (2) Select appropriate packaging raw materials and processing methods; (3) Use appropriate adhesives or laminating materials

in view of the application prospect of composite packaging materials in the packaging market, it is necessary to organize an investigation to find out the urgency of objective needs. At the same time, we should further master the research situation of composite packaging materials at home and abroad, and develop some urgently needed composite packaging materials

4 classification

up to now, there has been no systematic and exact induction on the classification of composite packaging materials. After years of research, most scholars tend to divide from the following four aspects:

(1) divide according to the materials used

because the basic materials commonly used in the packaging industry mainly include paper, plastic (material), aluminum foil, dry process paper (non-woven fabric), etc. If they are used to classify, there are paper/plastic composite packaging materials, aluminum/plastic/paper composite packaging materials, etc. This is a common traditional classification in the packaging industry, and it is also a well-known classification for many years

(2) according to the packaging requirements

due to the different contents of the packaging, the packaging requirements are also different. Therefore, there are fresh-keeping composite packaging materials, oil-resistant composite packaging materials, sterilization composite packaging materials, fire-proof composite packaging materials, etc. This classification has existed in the past, but has not been recognized by most people. However, from the perspective of clarifying the functions of packaging, it seems more convenient for customers to use

(3) divided by material properties

according to the properties of composite packaging materials, there are flexible composite packaging materials, rigid (hard) composite packaging materials, semi flexible composite packaging materials, etc. As the "definition" of soft and rigid is not very clear, some people think that this classification is not thorough, accurate and effective

(4) divided by composite method

according to the manufacturing method of composite packaging materials, 777000 vehicles can be sold: dry composite packaging materials, wet composite packaging materials, hot-melt composite packaging materials, extrusion composite packaging materials, etc. It was pointed out that there are many varieties of dry compounding only, and their properties are different,. The same is true for other methods. This classification is too "bold"

most of the above classifications are made artificially from different angles for the convenience of research. They are still in the exploration stage and do not have any accurate scientific basis for reference and discussion

II. General properties and characteristics of composite packaging materials

the properties of composite packaging materials are both common and special. Of course, this is closely related to the composition of the composite structure. In principle, as a composite packaging material, it should at least have the following properties:

(1) it should be protective and have sufficient mechanical strength, including tensile strength, rupture strength, folding strength, etc. In addition, there are water resistance, cold resistance, sealing, light resistance, moisture resistance, oil resistance, insulation, etc

(2) operability, that is, it is convenient for packaging operation, can adapt to mechanized operation, no slipping, no static electricity, anti curling, good isolation resistance and crease retention

(3) commercial, suitable for printing, convenient for circulation and reasonable price. There is an advertisement saying, "you have a product, I have a package". In short, composite packaging materials are also a kind of commodity. In order to stand firm in the market, they must have a strong edge. In the final analysis, it is necessary to control the economy. The threshold of "price" should be just as good as that expected by good experts by 2020

(4) hygienic, odorless, nontoxic and less pollution. The composite packaging materials shall be clean and shall not contain chemical components harmful to human health. Its recycling is still a problem, which deserves further study and proper solution

there are many characteristics of composite packaging materials, and the outstanding one will be introduced

(1) oil resistance: Oil impermeability is often one of the basic requirements for the materials used for food packaging. In order to prevent the penetration of oil and grease into the porous structure of paper, sometimes it is necessary to use film-forming materials to block the micropores, and it is better to use those without chemical affinity with grease. This means that the effect of using polar polymers is better, making them have good oil resistance and grease resistance. These polar polymers include carboxymethyl cellulose (CMC), ethyl cellulose (EC), methyl cellulose (MC), polyvinyl alcohol (PVA), styrene maleic anhydride copolymer (SMAC), etc

(2) heat sealing: some packaging operations require rapid heat sealing, so there should be higher requirements for the heat sealing coating selected for this composite packaging material. Under normal environmental conditions, it must be thermoplastic and non adhesive. Under the condition of heating and pressurization, it must become a strong adhesive. It remains firm even before the heat sealing zone and cooling zone. There are many kinds of polymers for heat sealing coatings, such as solvent based polymers such as ethyl cellulose, acrylic acid, ethylene copolymer, polyvinylidene chloride and polyvinyl acetate. Prepared from their mixture or wax, the range of heat sealing temperature is 100 ~ 180 ℃; For water-based materials such as polyvinyl chloride, polyethylene and vinyl acetate, the range of heat sealing temperature is 82 ~ 163 ℃

(3) barrier property: many foods require packaging materials to have certain oxygen resistance to prevent corruption and deterioration. At the same time, keeping the fragrance of the packaging bag is also related to its gas shielding ability. This characteristic of composite packaging materials (i.e. shielding capacity) is usually expressed by oxygen permeability coefficient. The so-called oxygen permeability coefficient (represented by P) is the volume of gas (cubic centimeter) passing through a thin film with a thickness of 1 cm per square centimeter area, time per second and mercury pressure per centimeter under standard pressure and temperature. Generally speaking, a certain component of composite packaging materials can indirectly reflect the shielding capacity. For example, low density polyethylene p=2.8; High and low density polyethylene p=0.4; Polypropylene p=2.3; PVDC p=0.005. There are great differences between them, so we must pay attention to the components in the materials

(4) pressure sensitive: instant stickers are pressure-sensitive composite packaging materials. In addition to making self-adhesive and labels, they can also make tape, transfer printing, wall covering materials, etc. It has different properties from ordinary adhesives. First, it has good adhesion ability in a wide temperature range with a very small pressure and a very short pressure time; Second, it can bond with various surfaces; Third, the ability to maintain contact with the surface for a long time, and not easy to aging

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