The Indian flexible packaging market has seen expeditious growth within the past few years and has estimated potential to grow approximately to a value of INR ~ 640.38 billion by FY 2023, up from its FY 2017 value of INR 375 billion, expanding at a compound annual growth rate (CAGR) of ~10% from FY 2018 to FY 2023.
This is predominantly due to increase in demand and sales of FMCG goods – the fourth-largest sector in the Indian economy representing huge opportunity for flexible packaging – and sub-categories such as food and beverage industry, pharmaceutical industry, personal care industry, and material (plastic, paper, and aluminum) among others. Another major reason for the growth of the Indian flexible packaging market is the increased use of food-service outlets and beverages in India.
The printing ink resins market is experiencing moderate growth which is expected to continue in the near future, mainly driven by the highly growing Asia-Pacific regions. Characteristics include solvency, good flow, remarkable gloss, resin stability, dilutability, and provides good surface appearance and ink performance – these will be the key influencing factors for the global ink resins with an increased emphasis on its different applications and ink resins types.
The Indian printing ink industry has also been growing proportionally with the increasing growth of the Indian flexible packaging. Among different resin systems, the vinyl-based printing inks hold the largest share of nearly about 70-80% of the flexible packaging. Since Poly Ethylene Terephthalate (PET) film is the most frequently used substrate in the multi-layer packaging of the products including food and beverages, personal care and others. The vinyl-based printing inks are proved to be the most suitable printing ink option for PET films, as vinyl resins are versatile, compatible and inexpensive due to their solubility in solvents like toluene.
Ethylene Vinyl Acetate Co-Polymer resin is the most extensively used vinyl-based resin in designing the vinyl-based printing inks. Traditionally, in Indian and Asian subcontinents, Vinyl acetate-Vinyl Chloride-vinyl alcohol terpolymer (popularly known as vinyl resin) and Ethylene Vinyl Acetate (EVA) based inks are known as vinyl inks. Vinyl resin aids in pigment grinding and EVA (Ethylene Vinyl Acetate) assists in promoting the adhesion of the printing ink. One of the major characteristics of vinyl resin is that it is soluble in toluene.
A co-polymer of Ethylene and Vinyl acetate, Ethylene-vinyl acetate or EVA is an extremely elastic and tough thermoplastic owning characteristics such as excellent clarity and gloss and with little odor. EVA possesses many attractive properties including low cost, excellent adhesion to many polar and nonporous substrates. This thermoplastic resin with low melt index (MI) offers high strength, superior viscosity, good flex-crack and puncture resistance and hot tack (relative melting and bonding strength) and heat sealing as compared to its high melt index counterparts. EVA co-polymers containing about 10% to 30% vinyl acetate, with the remainder being ethylene, are used for innumerable applications in the packaging and plastic goods industries.
Basically, there are three different types of EVA co-polymer, which differ in the vinyl acetate (VA) content and the fashion the materials are used. The EVA co-polymer having a low proportion of VA (nearly up to 4%) may be referred to as vinyl acetate modified polyethylene, which is processed as a thermoplastics material – just like low-density polyethylene. It contains some of the properties similar to low-density polyethylene but increased gloss (useful for film), softness and flexibility. The material is generally considered non-toxic.
In India, Ethyl vinyl Acetate-based Copolymer resins are colossally imported from countries including China, France, Europe, UAE and others for manufacturing printing inks, particularly for FMCG applications to a large extent. Elvax 40 W by Jotun UAE Ltd, Evaflex EV40 W by Mitsui & Co. Ltd and Evatane; Grade 42-60 by Arkema France are the known brands consumed by the printing ink manufacturers. A large quantity of these EVA resins is imported to India. Japan, France and UAE are the largest exporters of EVA based resin worldwide. Nearly, 272 MT of Evaflex EV40 W, 220 MT of Evatane; Grade 42-60 and 30.35 MT of Elvax 40 W are imported to India every year.
The major issues associated with vinyl resins are many. Vinyl-based printing inks (approximately 70 to 80%) are majorly toluene-based inks. But, the circumstances are straightway changing due to the new updates in Food Safety Regulations and standards in India. In July 2020 BIS revised the IS 15495 for printing inks for food packaging applications and included toluene in the negative list called Annexure A. This means that the toluene-based printing inks are no longer allowed to be used for food packaging applications. Technically, these vinyl inks are suitable for PET substrates and BOPP films, it requires additional additives that are added during the printing process; it not only involves costly imported material but also the availability of these additives these days. Besides, vinyl inks are limited performance in the medium-high, and high-end lamination and packaging requirements due to inadequate lamination strength and other post-print requirements. Another issue linked to vinyl inks is their low performance at higher printing speeds, thereby limiting its use in high-end printing machines.
Today, the printing ink manufacturers are shifting towards polyurethane-based printing inks as an alternative. Generally, polyurethanes have three basic building blocks a polyol, diisocyanate and the chain extender. They are versatile polymeric compounds formed by reacting a polyol (an alcohol with more than two reactive hydroxyl groups per molecule) with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts. The properties of the polyurethanes are determined with the segment flexibility, chain entanglement and inter-chain forces. The following factors affect the properties of the polyurethanes- molecular weight, intermolecular forces, blocking units. PURs can be designed to range from very hard to soft to tacky.
The molecular weight of the polyurethanes is one of the most important characteristics. As the molecular weight varies, the properties of the polyurethane resin change. Intermolecular forces between the polymeric chains is another factor that greatly influences the nature and properties of the polyurethanes. Further, polyesters and polyethers are usually two types of building blocks that also determine the properties of these polymeric compounds. Polyethers, on the other hand, provide good elasticity, flexibility and in-can stability. Polyesters provide toughness good weathering, good abrasion resistance and chemical resistance. Last but not the least, the variety of isocyanate used for formulating the PUR is also crucial. Usually, aliphatic isocyanates improve hydrolytic stability and resist UV degradation.
Since a range of diisocyanates and polyols can be used to produce polyurethane, a broad spectrum of materials can be produced to meet the needs for specific applications. For instance, for retort or high-end lamination packaging where the packaged food is subjected to high temperature while microwave cooking, PUR resins that can provide high heat resistance and bond strength and have the ability to grind pigments without any hard resins such as nitrocellulose under such challenging conditions are required. In such conditions, nitrocellulose based inks having the potential to promote the formation of nitrosamines when subjected to high temperature cannot be used.
The various performance requirements of an ink, packaging design and end-user application often demand that the ink maker utilizes two or more resins in a formulation to be successful. For example, nitrocellulose/polyurethane, nitrocellulose/ acrylic, PVC derivatives, PVB and polyamides are some simple generic examples of the resin systems required to meet the demands of the converters and brand owners.
However, it becomes highly inconvenient and confusing to both the ink manufacturer and converter as well to maintain a large inventory of various resins and inks to solve the myriad of customer demands. Nonetheless, this is not an issue with polyurethane resin since they can be customized based on the requirements. In recent years, urethane polymers have received intense attention in the ink, coating and adhesives industries, resulting in the synthesis of many specialized forms.
Further, polyurethane-based printing inks provide better bond strength in multilayer packaging, enhanced printability even at high-speed printing presses, affinity to different types of substrates, lamination compatibility with both solventless and solvent-based adhesives. These inks are also suitable for the extrusion lamination process. PUR are easily soluble in both aromatic and non-aromatic solvents. As the Indian printing and packaging industry has been shifting to toluene-free printing, PUR based inks are emerging as the most suitable option among other resin solutions available.
Along with toluene-free printing inks for food packaging, another factor that influences the growth of polyurethane resins is the rise in the utilization of solventless adhesives in the lamination process and the evolution of high-speed presses. Solventless adhesives contribute in reducing VOC emissions. And unlike solvent-based adhesive laminations, they also do not require much energy to dry. However, the chemistry of the solventless adhesives introduces the challenge of smearing the print. Polyurethane resins that provide greater resistance to solventless adhesives will make for a more robust ink system.
Yansefu’s customized polyurethane binders and raw materials
Yansefu designs and manufactures customized polyurethane binders and raw materials at their in-house production facility for designing high-performance cost-effective and innovative printing ink and adhesives to accomplish the customer’s specific requirements. Most of the indigenous polyurethanes developed at Yansefu R&D, have been protected through patents. Yansefu develops its ink technology to the highest standards of product safety. At Yansefu, the team focuses more on its customer’s and market requirements. The dedicated sales and technical team constantly monitor the current and future trends that eventually help us to understand the needs better and develop the most optimum commercial and technical solutions possible.
Authors: JK Sharma, CEO; and Neelakamal Mohapatra, VP, R&D, Yansefu Inks and Coatings Private Limited