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Q What are low viscosity adhesives and high viscosity adhesives?
A High viscosity or low viscosity adhesive is a common name in the industry, so far there is no unified standard to define.
It is generally believed that the viscosity at room temperature above 4000 mpsec is called high viscosity adhesive, and below 4000 mpsec is called low viscosity adhesive.
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Q what is solventless single component adhesive?
A Single component adhesive refers to the adhesive that single component of the glue liquid contact with air moisture can react curing and produce adhesive action
Solventless one-component adhesives are generally -NCO terminated polyisocyanate prepolymer, which relies on water to complete its curing process.
After curing, the single component adhesive is elastic, aging resistance, good laminating strength and mechanical strength. However, due to its lower molecular weight, its heat resistance is poor (<100 ℃); Its curing speed is relatively slow, and it is greatly affected by moisture, and it is easy to generate CO2 bubbles. When the coating amount is large or the water supply is insufficient, the curing is poor.
Single component solventless adhesive is mainly suitable for the laminate of fiber base materials, such as paper/plastic lamination or paper/paper lamination.
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Q What is two-component adhesive?
A Two component adhesive prefers to the adhesive of two component mixed with a certain percentage and produced adhesive action by reaction curing.
The two components of solventless adhesive are conventionally called component A and component B, also known as glue A and glue B. Component A is polyurethane prepolymer containing terminated isocyanate group, and component B is a lamination of polyester polyol and polyether polyol containing hydroxy-terminated benzene butadiene liquid rubber and/or carboxy-terminated nitrile liquid rubber.
Two - component adhesive can be used for various flexible packaging laminated base material
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Q What’s the type of solventless adhesive?
A At present, almost 100% of the solventless adhesives used for packaging belong to polyurethane adhesives.
According to the different components used, solventless polyurethane adhesives have two categories: two component type and single-component type. The reaction curing principle is similar, but the characteristics, operation mode and application scopes of adhesives are different.
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Q Advantages of solventless lamination?
A Compared with traditional solvent-based dry lamination, solventless lamination has many advantages, including at least following aspects:
1) No solvent emissions in the whole process. Because no volatile organic solvent is used, no pollution is generated in the solventless lamination production process, users can achieve “zero emissions” and clean production.
2) Product has no solvent residue. Because there is no solvent residue in the lamination process, can obtained a safe and health package, as to ensure the safety of the contents, especially suitable for food, drugs, maternal and child products and other products with high health requirements.
3) No safety risks such as explosion and fire. Solventless lamination production areas have no safety hazards such as explosion and fire caused by solvent, do not need to be equipped with fire and explosion prevention and other safety facilities, it is of great significance for the enterprise personal and property safety.
4) High production efficiency. The production speed of solventless lamination machine can generally reach 250-350m/min(a few can reach 450-60m/min), which is nearly double the efficiency of the vase dry lamination machines, and the assistant time of production is relatively less.
5) Significant energy saving. Due to the low operating temperature and no need to use drying system, the overall energy saving is about two thirds than that of dry lamination machine drying.
6) Low comprehensive cost. Duo to the above reasons, with less gluing weight and lower gluing cost, the comprehensive cost of solventless lamination is significantly lower than that of solvent-based dry lamination.
Solventless lamination is an international recognized green lamination technology, which is the development direction and future leading technology of the whole laminated flexible packaging.
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Q The development process of solventless lamination?
A The solventless lamination process began in Germany in the 1970s. In 1974, Herberts Company in Germany put the solventless adhesive of one component into industrial production, marking the beginning of the formal promotion of solventless lamination. In the 1980s, solventless lamination technology developed rapidly in developed countries such as Europe and America. In the late 1990s, Japan also gradually began to pay attention to solventless lamination and made some progress. In India, Russia, Brazil and
other countries, solventless lamination has gradually become the leading lamination technology.
At present in Europe and the United States, the proportion of solventless lamination has reached 70-80%, lamination machine accounted for about 90% of new lamination machine.
In 1984-1985, Beijing Research Institute of Chemical Industry introduced solventless polyurethane adhesive production technology and equipment from Germany Henkel Company, which marked the beginning of solventless lamination technology in China. In the following two decades, although about 30 solventless lamination production lines were introduced in China, the overall development of solventless lamination in China has been quite slow.
In 2008, the first domestic solventless lamination machine independently developed by Guangzhou Sinomech Machinery Co., Ltd. was put into the market, and then domestic adhesive suppliers also launched solventless adhesive products, and the promotion of domestic solventless lamination officially began to enter a new stage of development.
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Q What is solventless lamination?
A Solventless lamination is a technology that uses polyurethane adhesive to bond different base materials together by reaction curing to obtain new functional materials. Solventless lamination is named because it does not require the use of volatile solvents throughout the lamination process, in order to distinguish it from the traditional solvent-based lamination process.
Polyurethane adhesives usually have two components (called main agent and curing agent, also known as A and B adhesives) and single component adhesives. In the field of flexible packaging, the laminate base material is usually a variety of plastic film, aluminized film, thin paper and aluminum foil, often using two-component adhesive. In the paper - plastic lamination field, always use single - component adhesive.
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Q What is dry light packaging, boiling packaging, heavy packaging？
A Dry light packaging usually refers to the packaging of dry, light weight items. Dry articles refer to those that do not contain obvious moisture, grease, solvents and other media; Light weight means usually under a few kilograms (e.g. 5 kilograms).
Steaming package is a package that is not broken, cracked, contracted or smelly after a certain period of high temperature cooking (sterilization). It usually includes three categories: boiled package (100℃), high temperature cooking (120℃) and super high temperature cooking (135℃). retort pouch is a kind of laminate plastic film pouch, food can be left untouched in the bag, after high temperature sterilization heating, take out and eat. It is an ideal sales packaging container. Suitable for meat, soy products packaging, convenient, health and practical, and can well kept the original flavor of food, much welcomed by consumers.
Heavy packaging refers to the packaging that is suitable for the heavy weight of the object to be packed. In the field of flexible packaging, usually refers to more than 5 or 10 kg of packaging, mostly used for packaging plastic raw materials, fertilizer, feed, rice, grain and laundry powder.
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Q What is functional packaging?
A Functional packaging refers to the packaging that has some unconventional functions and produces effective added value. These functions may include such as ① protective function, ② hygienic function, ③ convenience function, ④ environment suitable function and ⑤ information transmission function.
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Q What is packaging solvent residue?
A Solvent residue refers to organic volatile compounds (VOC) that are not completely removed during the production process of packaging. The solvent residue of laminated packaging mainly comes from two processes: printing and lamination.
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Q What is VOC?
A VOC is short for volatile organic compounds.
Different organization define VOC differently, for example:
1) In ASTM D3960-98, VOC is defined as any organic compound that can participate in atmospheric photochemical reactions.
2) The United States Environmental Protection Agency (EPA) defines volatile organic compounds as any carbon compound participating in atmospheric photochemical reactions except CO, CO2, H2CO3, metal carbides, metal carbonates and ammonium carbonate.
3) The World Health Organization (WHO,1989) defines total volatile organic compounds (TVOC) as the general term for volatile organic compounds whose melting point is lower than room temperature and boiling point is between 50 and 260℃
4) The international standard ISO 4618/1-1998 and the German standard DIN 55649-2000 for generic terms for paints and varnishes define VOC as, in principle, any organic liquid and/or solid that can spontaneously evaporate at room temperature and pressure. In the determination of VOC content, the German DIN 55649-2000 standard makes a further restriction, that is, under normal pressure conditions, the boiling point or initial distillation point of any organic compound below or equal to 250℃.
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Q Similarities and differences between dry lamination and solvent-based lamination?
A Dry lamination refers to the process that after coating the adhesive, drying the adhesive first and then laminating. It’s relative process is wet lamination, which prefers to the process after coating the adhesive, laminating first and then drying.
Dry lamination mainly uses two kinds of adhesives, one is solvent-based adhesives, accounting for the vast majority of dry lamination. Another type of water-based adhesive, only accounted for a small proportion of dry lamination. So solvent - based lamination is a common type of dry lamination. In practical communication, many people confuse the two.
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Q Layers of laminated flexible packaging and its relative material?
A Laminated flexible packaging is usually bonded by three (layers) of functional materials, namely printed layer, barrier layer and heat seal layer. Common material for each layer including: Printed layer: BOPP, PET, Nylon, Paper, etc. Barrier layer: VMCPP, VMBOPP, VMPET, Aluminum foil, etc. Heat seal layer: PE(LLDPE), CPP, etc. Because some material not only have good printing performance, but also have good barrier performance, such as PET; and some other materials have both good barrier and heat seal performance, such as VMCPP, therefore, in the practical application according to the characteristics of the material itself, different use requirements and habits, there can be two layers, three layers or multi-layer laminating structure, such as BOPP/PE, BOPP/CPP, BOPP/VMCPP, PET/PE, PET/CPP and so on. In practical application, the proportion of two-layer structure is larger than that of three-layer structure. 
reduction is the basic requirement of modern packaging according to the international development trend, therefore, on the premise of meeting the performance, the fewer the laminating layers, the better. -
Q Main processes of flexible packaging lamination?
A Solventless lamination, dry lamination, wet lamination, and extrusion lamination, etc.
Dry lamination refers to the process that the flexible base material coated with adhesive, drying first, so that the solvent or moisture in the adhesive fully volatilized and the initial adhesion and binding force of the adhesive are improved, then bonding with another base material under pressure. It’s suitable for the laminating of various flexible packaging base materials (plastic film, aluminum foil and paper, etc.).
Wet lamination prefers to the process that the flexible base material coated with adhesive, first bonding with another base material under pressure, then drying, so that the solvent or moisture in the adhesive fully volatilized and the initial adhesion and binding force of the adhesive are improved. It’s generally only used for the laminating of porous materials (such as paper, etc.).
Extrusion lamination refers to the process of using an extruder to plasticize thermoplastic (usually polyethylene) and extrude it through the die head as a film, pressing the molten resin and the base material between two rollers, and then making laminated film after cooling.
Solventless lamination is a technology that uses polyurethane adhesive to bond different base materials together by reaction curing to obtain new functional materials
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Q Common processes of laminated flexible packaging?
A Printing—→Laminating—→Slitting—→Bag making
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Q 3.What is laminated flexible packaging?
A Briefly, the flexible packaging made by laminated material or laminated film are called laminated flexible package. Because most
of flexible packaging product is laminated flexible packaging, so the flexible packaging and laminated flexible packaging is commonly not strictly distinguished.
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Q Why the same brand of adhesive may have different conditions in different regions, different seasons, different times of the day
A Because different regions, different seasons, different times of the day may have different temperatures and humidity. The difference of temperature and humidity will have a certain impact on coating and curing.
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Q What is laminating and laminated materials?
A Laminating refers to a process in which two or more layers of materials with different properties are joined together by adhesives to form new functional materials
Because a variety of packaging materials have different characteristics (such as printing suitability, barrier, transparency, heat sealing, etc.), so they can be properly combined and laminate together to get the required, and a single material does not have the performance.
Laminated material is a new material obtained by laminating technology. As plastic film is the most commonly used base material in flexible packaging, laminated materials are also commonly known as laminated film.
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Q What is the change rule lamination strength of solventless adhesive? How long dose it take to reach the maximum lamination strength
A The solventless lamination strength changes with time from the beginning of adhesive mixing, and the lamination strength from the beginning of mixing to reach the maximum strength, then slowly decay, roughly through the following stages: 1) opening period, 2) rapid curing stage, 3) slow curing stage, 4) stable stage, and 5) slow decay stage and so on.
Usually, the lamination strength changing curve of different brands of adhesive is also different. Commonly can reach the 70~80% of maximum strength within 72 hours, it takes 7 to 15 days to reach maximum strength.
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Q What is flexible package?
A Flexible package usually refers to the packaging whose shape can be changed after filling or removing the contents. All kinds of bags, boxes, sleeves and envelopes made of plastic film, aluminized film, paper, aluminum foil, etc., and their compounds are flexible packaging.
