Physical properties and application of the hottest

2022-09-21
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Physical properties and use of polyurethane ink connecting materials

I. preface

polyurethane ink connecting materials have the advantages of simple use, stable performance, strong adhesion, excellent gloss, good heat resistance and so on. They can be suitable for various printing methods, especially for plate printing, plastic packaging and composite films aimed at meeting the different needs of customers. In recent years, many domestic production and research institutions have been engaged in the research of polyurethane ink connecting materials, and achieved good results. For example, 121 ℃ and 135 ℃ cooking ink connecting materials have been put into production and widely promoted in the market. However, there is a certain gap between the comprehensive performance of products and imported products. Improving the comprehensive performance of products and developing multi-functional products are the focus of domestic research on polyurethane ink binder

with the rapid economic growth, domestic plastic printing inks and food packaging printing inks have shown an upward trend, but the relevant polyurethane ink connecting materials have not been developed and produced in time. In terms of food packaging, such as milk bags, the materials are low polarity materials such as BOPP, and they need to be resistant to boiling and sunlight, so the application requirements of connecting materials are high. In particular, for the solvent of ink connecting materials, because many European and American food enterprises' internal control quality standards stipulate that aromatic hydrocarbons should not be added to all packaging materials, China has also begun to issue an order to prohibit the use of aromatic hydrocarbon toxic solvents in food printing inks from the perspective of environmental protection and the safety of users. In order to meet this requirement, benzene free inks should be shipped, which limits their use in household appliances, especially high-end outdoor household appliances. Theoretically, this kind of ink does not contain aromatic hydrocarbon solvents, but due to the storage of raw materials, means of transportation, manufacturing process and use process, a small amount of aromatic hydrocarbon solvents will be mixed more or less, so the understanding of benzene free should be the aromatic hydrocarbon content 1 in the system

due to the rapid development of the national ink industry, polyurethane ink binder will develop rapidly in the future with its unique performance advantages. At the same time, due to the increasing awareness of environmental protection, the original benzene polyurethane ink binder is destined to be eliminated because of its toxicity, although its performance is superior. The development of benzene free polyurethane ink binder will be an inevitable trend

it is particularly important to point out that due to the increasingly strict requirements of the state on environmental protection, benzene solvent based ink products that are widely used now have a large number of toxic solvents volatilizing and a small amount of residues in the process of use, which not only pollutes the environment but also damages the physical and mental health of workers, especially the bag making products produced with benzene binder on soft food packaging have been constantly exposed, which is called poison bags. At present, the country has expressly prohibited the use of ink containing toluene in the food flexible packaging industry. The operation of benzene free ink plastic granulator covers an extremely wide range of fields, and water-based ink and alcohol soluble ink have been greatly developed. Water based gravure printing ink as an alternative system of toluene ink has attracted attention, but there have been many obstacles in the hydration of ink in packaging film printing. The main reason is that the printing adaptability and printing quality can not meet the standard of solvent based ink, because the surface tension of water is too high, and the wettability on the surface of film substrate is poor. In order to obtain the printing quality of solvent based ink, in addition to the improvement of water-based ink technology, the printing equipment and printing plate rollers also need to be improved. Based on the above reasons, the ink industry has focused on the development of ketone soluble, alcohol ester soluble and alcohol soluble inks

II. Physical properties and use of polyurethane connecting materials

1 Main product models and physical properties

2 Product characteristics

(1) excellent adhesion and good connectivity

(2) good film formation and solvent release

(3) good compatibility with solvents such as esters and alcohols

(4) good yellowing resistance, hydrolysis resistance and medium resistance

(5) good dispersibility, wetting and leveling, and the gravure ink configured has strong printing adaptability

3. Product use

(1) dissolution and dilution: the main solvent of the resin is butanone, ethyl acetate, isopropanol and other organic solvents. At the same time, according to different needs, an appropriate amount of medium boiling point solvent with good solubility and moderate volatilization speed can be added to the ink. Such as methyl isobutyl ketone, n-butyl acetate, n-Propyl Acetate, n-propanol, propylene glycol methyl ether and other organic solvents, the solvent dissolution parameters and evaporation rate of the ink system are adjusted appropriately, so as to further improve the adhesion and color development of the ink system, so that the prepared ink can achieve the best printability

(2) the product has good compatibility with various resins (chloroacetic acid resin, PVB resin, aldehyde ketone resin, nitrocellulose and other resins and cellulose, etc.) and shows good compatibility. In order to improve the comprehensive performance of the ink, the above resin and fiber rope are often used together with PU resin in the preparation of the ink, and as the grinding medium of the pigment. It is recommended that careful material tests be carried out before use to ensure that the resin or cellulose has good solubility in the ink solvent, and that there is better compatibility between the resin and the resin, and between the resin and the cellulose

(3) in order to improve the smoothness of the ink system, a certain amount of polyethylene wax (wax powder or wax liquid) is often added to the ink

(4) polyurethane resin is a polar material. In order to improve the adhesion of ink to PP, PE and other non-polar substrates, an appropriate amount of PP or PE adhesion promoter should be added

(5) when printing is used for cooking, an appropriate amount of hardener can be added to improve the adhesion and heat resistance of the ink

III. conclusion

ketone soluble, phenol soluble and alcohol soluble inks can effectively solve the health damage caused by toluene based inks and the impact of solvent residues on the quality of packaged food. This has become a trend in European and American countries, and some countries in Asia have already begun to replace toluene soluble ink. In recent years, due to the introduction of mandatory policies, benzene ink bonding materials will gradually be introduced into the historical stage in China. It can be predicted that in the near future, benzene free solvent polyurethane ink connectors will occupy the main share of China's food and drug packaging ink market

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