Analysis of the current situation of the most popu

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Analysis of the current situation of commonly used adhesives in flexible packaging

application status of adhesives

at present, the commonly used composite adhesives in the flexible packaging industry mainly include solvent-free adhesives, water-based adhesives and solvent-based adhesives. Developed countries in Europe and the United States attach great importance to environmental protection, and solvent-free adhesives and water-based adhesives are mainly used in flexible packaging composite production. In most countries in Asia and Africa, solvent based adhesives are still the main flexible packaging manufacturers. For example, in Japan, where the flexible packaging industry is relatively developed, solvent based adhesives account for more than 90% of the market share

according to incomplete statistics, there are more than 6000 flexible packaging production enterprises in China, mainly concentrated in the Pearl River Delta, Yangtze River Delta and some areas of Hebei and Shandong provinces. In these areas, more than 95% of flexible packaging manufacturing enterprises use solvent-based adhesives, and less than 5% of enterprises use environmental friendly adhesives (solvent-free adhesives and water-based adhesives)

at present, there are nearly 400 manufacturers of adhesives for flexible packaging in China. It is estimated that the annual production of adhesives in China is about 60000 tons, of which solvent adhesives still occupy the main position. More well-known production enterprises include Zhongshan Kanghe, Zhejiang New Oriental, Shanghai lieyin, Beijing GAOMENG, Beijing Research Institute of chemical industry (Beihua Institute), Jiangsu Jintan, etc. In recent years, some famous foreign adhesive manufacturers have also increased their investment and development efforts in the Chinese market, and have built factories in China, such as Henkel, Mitsui Takeda, Rohm Haas, bright and other companies. The participation of international manufacturers has greatly improved the production level and production capacity of adhesives in the domestic market

types and characteristics of adhesives

the three types of adhesives commonly used in the flexible packaging industry have their own characteristics and corresponding application fields. Their advantages and disadvantages are briefly analyzed and summarized below

1. Solvent based adhesives

solvent based adhesives for flexible packaging composites mainly include two-component polyester, two-component polyether, two-component polyurethane and alcohol soluble polyurethane

(1) advantages

① it is applicable to a wide range of substrates and has good adhesion to commonly used materials in flexible packaging composites

② good initial adhesion and high composite strength

③ the composite film has high transparency and good flexibility, which meets the requirements of post-processing procedures and product packaging

④ heat resistance, cold resistance, medium resistance and other properties are the best among all kinds of adhesives

⑤ it is safe, hygienic and odorless, and meets the requirements of FDA standards and the relevant provisions of VOC (organic volatile matter)

⑥ good operability, relatively low requirements for equipment and operators

(2) disadvantages

① volatile organic solvents are harmful to human body and cause certain pollution to the environment

② incomplete free TDI (toluene diisocyanate) in some ester soluble adhesives is harmful to human body

③ there is a small amount of solvent residue in the composite film, which may pollute the contents of the package

2. Water based adhesives

flexible packaging composite water-based adhesives mainly include water-based polyurethane adhesives and water-based acrylic adhesives

(1) advantages

① it does not pollute the environment and is conducive to environmental protection

② it can be used on medium and high-speed compound machines

③ there is no solvent residue, and the transparency of the composite membrane is high

④ the composite strength of the aluminized film is good, which will not damage the aluminized layer or cause the transfer of the aluminized layer

⑤ the amount of glue applied is small (as low as 1.6g/m2), and the comprehensive use cost is low

⑥ it has good adaptability to alcohol soluble inks

(2) disadvantages

① it is not suitable for heavy packaging and high-temperature cooking packaging

② the requirements for the surface properties of the film are relatively strict, and the surface tension is higher than 3.8 × N/m。

③ large energy consumption and low production efficiency require the composite equipment to have strong heating and ventilation capacity (the temperature should reach 60 ~ 100 ℃)

④ the composite strength decreases obviously with time

⑤ the corrosion of composite equipment is serious

⑥ when the composite aluminum coating is applied, the aluminum coating is easy to be corroded

3. Solventless adhesives

solventless adhesives for flexible packaging composite mainly include single component, two-component, UV curing and EB curing

(1) advantages

① non toxic, environmental friendly, solvent-free volatilization, no environmental pollution, in line with FDA standards

② the operation is safe, and there is no need to take fire and explosion-proof measures

③ the amount of glue applied is small, the compounding process is simple, and the compounding speed can reach 200 ~ 300m/min

④ save energy. After gluing, there is no need to heat and dry through the drying channel, and the energy consumption will not be increased due to waste gas incineration or recycling

⑤ composite products do not have solvent residue or migration problems, so they will not pollute the contents, which is more suitable for food packaging

⑥ the solid content can reach 100%, and the comprehensive use cost of users is low

(2) disadvantages

① the investment of solvent-free compounding equipment is large, and the coating system is complex, and heating devices are required

② the glue liquid has high viscosity and short storage time after mixing

③ low initial adhesion and long curing time

④ it has high requirements for the accuracy of the tension system of composite equipment and the operation level of operators

⑤ the flatness and thickness of the composite substrate are strictly required, and the surface tension of the film should be greater than 3.8 × N/m。

⑥ the composite strength decreases with time

⑦ when compounding some packaging products with high quality requirements (pesticide bags, high temperature cooking bags, etc.), their performance and compounding quality cannot reach the level of ester soluble polyurethane adhesive

the domestic adhesive market is stable and innovative

the overall situation of the domestic and foreign flexible packaging industry is that various adhesive products have their own markets, but the development direction is to adopt safe and environmentally friendly products and produce green packaging

1. Various adhesive products coexist

(1) solvent based adhesives have obvious advantages in the domestic market due to their excellent softness, low temperature resistance, cooking resistance, ease of operation and wide adaptability, and other adhesives cannot be replaced temporarily

(2) in practical application, solvent-free adhesives, hot-melt adhesives and water-based adhesives still have some practical problems that cannot be solved temporarily. ① At present, the dry compounding equipment in the domestic flexible packaging industry is only suitable for solvent based adhesives. If you want to replace the compounding equipment, you need to invest a lot of money, which will cause a lot of waste of resources; ② Environmental friendly adhesives have certain limitations in performance; ③ The extra heat energy consumed is also a waste of environmental resources, and will also cause pollution to the environment

(3) the flexible packaging industry has begun to pay attention to environmental protection. Only by completely changing the emission of harmful substances in raw and auxiliary materials such as adhesives, inks, solvents, films, etc., can the goal of environmental protection packaging be fundamentally achieved

(4) at present, the harm of solvents to the environment has not been determined. Internationally, Japan and European and American countries still have disputes on this issue, and some solvent adhesives have also passed the FDA certification and the relevant provisions of VOC

2. Environmental friendly adhesives are the development direction

it is undeniable that the domestic adhesive market is towards environmental protection. Polyurethane technology was first invented and developed by OttoBayer, a scientist created by Kos, in 1937, which is an inevitable trend. In 2004, water-based adhesive manufacturers seized the opportunity of rising prices in the international oil market and made great progress in the environmental friendly adhesive market, but only one component water-based adhesives are mainly used for light-weight packaging with simple composite structure. Solvent free adhesives have not made much progress due to the influence of equipment and other factors

however, we should also see that solvent based adhesives will still be the mainstream products in the domestic market for a long time in the future, and will be improved in environmental protection: first, develop some transitional and solvent based adhesives, such as low solvent residue adhesives, aliphatic polyurethane adhesives, alcohol soluble adhesives, etc; The second is to develop solvent-free composite equipment with low cost and simple operation

some domestic adhesive manufacturers pay great attention to the research and development of environmental friendly adhesives and carry out relevant technical reserves. As long as the domestic market is mature, they can produce them at any time to meet the needs of customers. For example, Zhongshan Kanghe Chemical Co., Ltd. developed a two-component solvent-free adhesive kh-fs762/kh-1762 as early as 2003, and independently developed a one component aqueous adhesive kh-wb607 (for paper/plastic lamination to be completed in 10 minutes) and kh-wb608 (for plastic/plastic lamination). At the same time, Kanghe chemical also launched KH quality inspection, which has achieved remarkable results in the past seven years -ls800/3800 ultra-low solvent residual polyurethane adhesive, to meet the environmental protection requirements of domestic flexible packaging manufacturers and end users at this stage. In addition, Kanghe chemical is actively cooperating with mechanical equipment manufacturers to devote itself to the application research of solvent-free adhesives on ordinary dry laminating machines, and has made breakthrough progress

with the development of technology, it is believed that domestic environmental friendly adhesives will make greater progress in the future, and play a positive role in promoting the environmental protection of the first batch of insurance compensation work of provincial new materials

source: Chinese glue

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