4) Liquid Packaging
The so-called liquid packaging film is the content of the liquid packaging film, according to the printing method it can be divided into table printing liquid packaging film and the printing liquid packaging film.
Surface printing liquid packaging film generally uses three-layer co-extruded or five-layer co-extruded PE film (black and white film, milk film, matt film, packaging machine 'target=_blank> transparent film), mainly used for milk, soy milk, soy sauce, vinegar Such as liquid packaging and frozen meat food frozen packaging. The liquid packaging film needs to undergo a uniform corona treatment before printing, and the surface tension at the boundary should reach 40 to 41 dyne. Commonly used in India liquid packaging film such as milk film packaging can use biaxially oriented polypropylene (BOPP) and matte polypropylene (BOPP), polyethylene terephthalate (PET), etc. as the substrate for printing, with high The strength of metallocene polyethylene as a film substrate. For the three-layer composites, PET film can be used for printing. The middle layer is made of aluminum foil or PET aluminum film because they have good barrier properties, and then they are composited with metallocene polyethylene with good heat-sealability and high strength. For liquid packaging films such as cosmetics and pesticides, PET is used as the printing surface material, aluminum foil or PET aluminum film is used as the intermediate layer, and metallocene polyethylene is used as the third layer. Commonly used film combination method: PET film/PET aluminum film/metallocene polyethylene film or PET film/aluminum foil/metallocene polyethylene film. PET has high mechanical strength, strong toughness and excellent dimensional stability, so it is often used as the surface layer of liquid packaging film. In the printing of PET substrates, the surface tension of the printing surface is required to be more than 50 dynes, and the PET aluminum film in the middle layer of the composite film should be treated with corona on both sides.
5) Cooking Package
The so-called retort packaging is the packaging of the contents, placed in a steam boiler at 120 °C cooking 40 minutes without breaking the package. Commonly used structures are PA/PE, PA/CPP, PET/AL/CPP.
Polyamide (PA) is commonly known as nylon. Nylon film is an OPA or CPA film made of nylon 6 resin after biaxial stretching. It has high strength and can maintain high modulus and stiffness over a wide temperature range. With high oxygen barrier properties, puncture strength, tear strength, high temperature performance and printability and many other advantages. Nylon film also has high transparency and safety. Based on these advantages, nylon films have been widely used in food packaging, pharmaceutical packaging and industrial packaging. For example, 12 μm PA is compounded with 30-80 μm CPP or PE, wherein nylon has puncture resistance, high impact strength and high temperature stability, while other resins such as polyethylene and unstretched polypropylene have excellent heat. Sealing and barrier properties. The compounded product has good refrigerating properties, good corrosion resistance, resistance to puncture, gas and fragrance protection, and high temperature cooking. The disadvantage is that it is easy to absorb moisture, the barrier property and strength after the moisture absorption decrease, the adhesion of the ink is reduced, and the film is wrinkled. Therefore, it should be noted that it should be stored in a dry place and the humidity of the printing environment should be changed.
In modern packaging, aluminum foil is used in many advanced composite materials that require no light transmission. Aluminum foil is made of electrolytic aluminum with a purity of 99.5% or more. It has good barrier properties, strong airtightness, moisture-proof and waterproof, and has strong protective properties against the content, thermal conductivity, etc., compared with materials such as paper plastic film. Excellent shading and other advantages, and non-toxic, can be combined with paper, plastic film and other materials, easy to print and color, so aluminum foil is currently not yet be replaced packaging materials, a very wide range of uses. Aluminum foils used in composite materials usually have a thickness of 7 to 9 μm. In practical use, except for the use of chocolate and pharmaceutical packaging, thickness selection should be based on different contents. There are four widths of aluminum foils produced in China: 10 to 39 mm, 39 to 130 mm, 130 to 220 mm, and 220 to 600 mm. There are 18 thicknesses, of which the thinnest is 5 μm and the thickest is 200 μm. Before printing, aluminum foil should undergo corresponding pretreatment, that is, coating with a layer of shellac or nitrocellulose to increase the adhesion of the ink.
BOPP/AL/LDPE is used for barrier light protection or evacuated flexible packaging, in which BOPP is used for pre-printing and after coating with polyurethane adhesive, it is first dry-composited with aluminum foil (thickness of 10-30 μm) and its color printing pattern After contrasting with silver-white aluminum foil, it is more glossy and colorful. Next, the adhesive is coated on the other side of the aluminum foil with a polyethylene substrate (thickness of 30 to 100 μm), and then cured, set, cut, and then bagged with T-seal, tri-seal, H-seal, etc., or directly It is sent to packaging lines such as food, medicine and cosmetics for automatic high-speed continuous packaging. The LDPE used to adhere to the AL surface is surface activated. In the above process, BOPP can be replaced with more rigid PET, and LDPE can be replaced with CPP. For example, 12 μm PET is compounded with a 7- to 14-μm aluminum foil by a dry compounding method and then compounded with a CPP of 30-80 μm. The compounded product has a gas barrier, moisture barrier, fragrance retention, high mechanical strength, retorting, and low temperature refrigeration. The characteristics are mainly used for the packaging of baked goods, meat products, butter, etc.
The above describes several common choices for packaging materials. In the actual production, we will encounter various types of packaging. We must consider not only the aesthetics of packaging, but also the characteristics of the contents of the packaging and the packaging methods. The packaging should choose what kind of material, not to "the civet cat for the Prince." If there are any mistakes in the choice of materials, the loss after packaging will be incalculable. Therefore, the printer is required to understand the characteristics and special requirements of the contents of the package before packaging, and then pay more attention to the selection of materials. For new product development, it is required to do a good job first and then mass production. It must be remembered that high quality flexible packaging products can only be made when everything is ready.
The so-called liquid packaging film is the content of the liquid packaging film, according to the printing method it can be divided into table printing liquid packaging film and the printing liquid packaging film.
Surface printing liquid packaging film generally uses three-layer co-extruded or five-layer co-extruded PE film (black and white film, milk film, matt film, packaging machine 'target=_blank> transparent film), mainly used for milk, soy milk, soy sauce, vinegar Such as liquid packaging and frozen meat food frozen packaging. The liquid packaging film needs to undergo a uniform corona treatment before printing, and the surface tension at the boundary should reach 40 to 41 dyne. Commonly used in India liquid packaging film such as milk film packaging can use biaxially oriented polypropylene (BOPP) and matte polypropylene (BOPP), polyethylene terephthalate (PET), etc. as the substrate for printing, with high The strength of metallocene polyethylene as a film substrate. For the three-layer composites, PET film can be used for printing. The middle layer is made of aluminum foil or PET aluminum film because they have good barrier properties, and then they are composited with metallocene polyethylene with good heat-sealability and high strength. For liquid packaging films such as cosmetics and pesticides, PET is used as the printing surface material, aluminum foil or PET aluminum film is used as the intermediate layer, and metallocene polyethylene is used as the third layer. Commonly used film combination method: PET film/PET aluminum film/metallocene polyethylene film or PET film/aluminum foil/metallocene polyethylene film. PET has high mechanical strength, strong toughness and excellent dimensional stability, so it is often used as the surface layer of liquid packaging film. In the printing of PET substrates, the surface tension of the printing surface is required to be more than 50 dynes, and the PET aluminum film in the middle layer of the composite film should be treated with corona on both sides.
5) Cooking Package
The so-called retort packaging is the packaging of the contents, placed in a steam boiler at 120 °C cooking 40 minutes without breaking the package. Commonly used structures are PA/PE, PA/CPP, PET/AL/CPP.
Polyamide (PA) is commonly known as nylon. Nylon film is an OPA or CPA film made of nylon 6 resin after biaxial stretching. It has high strength and can maintain high modulus and stiffness over a wide temperature range. With high oxygen barrier properties, puncture strength, tear strength, high temperature performance and printability and many other advantages. Nylon film also has high transparency and safety. Based on these advantages, nylon films have been widely used in food packaging, pharmaceutical packaging and industrial packaging. For example, 12 μm PA is compounded with 30-80 μm CPP or PE, wherein nylon has puncture resistance, high impact strength and high temperature stability, while other resins such as polyethylene and unstretched polypropylene have excellent heat. Sealing and barrier properties. The compounded product has good refrigerating properties, good corrosion resistance, resistance to puncture, gas and fragrance protection, and high temperature cooking. The disadvantage is that it is easy to absorb moisture, the barrier property and strength after the moisture absorption decrease, the adhesion of the ink is reduced, and the film is wrinkled. Therefore, it should be noted that it should be stored in a dry place and the humidity of the printing environment should be changed.
In modern packaging, aluminum foil is used in many advanced composite materials that require no light transmission. Aluminum foil is made of electrolytic aluminum with a purity of 99.5% or more. It has good barrier properties, strong airtightness, moisture-proof and waterproof, and has strong protective properties against the content, thermal conductivity, etc., compared with materials such as paper plastic film. Excellent shading and other advantages, and non-toxic, can be combined with paper, plastic film and other materials, easy to print and color, so aluminum foil is currently not yet be replaced packaging materials, a very wide range of uses. Aluminum foils used in composite materials usually have a thickness of 7 to 9 μm. In practical use, except for the use of chocolate and pharmaceutical packaging, thickness selection should be based on different contents. There are four widths of aluminum foils produced in China: 10 to 39 mm, 39 to 130 mm, 130 to 220 mm, and 220 to 600 mm. There are 18 thicknesses, of which the thinnest is 5 μm and the thickest is 200 μm. Before printing, aluminum foil should undergo corresponding pretreatment, that is, coating with a layer of shellac or nitrocellulose to increase the adhesion of the ink.
BOPP/AL/LDPE is used for barrier light protection or evacuated flexible packaging, in which BOPP is used for pre-printing and after coating with polyurethane adhesive, it is first dry-composited with aluminum foil (thickness of 10-30 μm) and its color printing pattern After contrasting with silver-white aluminum foil, it is more glossy and colorful. Next, the adhesive is coated on the other side of the aluminum foil with a polyethylene substrate (thickness of 30 to 100 μm), and then cured, set, cut, and then bagged with T-seal, tri-seal, H-seal, etc., or directly It is sent to packaging lines such as food, medicine and cosmetics for automatic high-speed continuous packaging. The LDPE used to adhere to the AL surface is surface activated. In the above process, BOPP can be replaced with more rigid PET, and LDPE can be replaced with CPP. For example, 12 μm PET is compounded with a 7- to 14-μm aluminum foil by a dry compounding method and then compounded with a CPP of 30-80 μm. The compounded product has a gas barrier, moisture barrier, fragrance retention, high mechanical strength, retorting, and low temperature refrigeration. The characteristics are mainly used for the packaging of baked goods, meat products, butter, etc.
The above describes several common choices for packaging materials. In the actual production, we will encounter various types of packaging. We must consider not only the aesthetics of packaging, but also the characteristics of the contents of the packaging and the packaging methods. The packaging should choose what kind of material, not to "the civet cat for the Prince." If there are any mistakes in the choice of materials, the loss after packaging will be incalculable. Therefore, the printer is required to understand the characteristics and special requirements of the contents of the package before packaging, and then pay more attention to the selection of materials. For new product development, it is required to do a good job first and then mass production. It must be remembered that high quality flexible packaging products can only be made when everything is ready.
Author Shi Peiqin Shandong Linyi Xingda Company Color Printing Factory
Source: "Printing World"
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