The main emission links of VOCs in the printing industry include printing, drying, laminating, and cleaning. The amount of VOCs emitted is closely related to printing consumables such as inks, adhesives, fountain solutions, wash water, and thinners. Based on this, printing companies must make corresponding improvements in the processes of printing, drying, laminating, and cleaning to gradually achieve environmental protection. The use of green raw materials and green printing processes, as well as organic solvent recovery technology, are currently advocated methods for reducing VOC emissions in the printing industry. Among them, water-based adhesives are environmentally friendly adhesives made from natural or synthetic polymers as binders and water as a solvent or dispersant to replace toxic organic solvents that pollute the environment. They have advantages such as non-toxicity, no pollution, non-flammability, safe use, and easy realization of clean production. Below, I will discuss some related matters about water-based adhesives!

How to choose water-based adhesives

1. Fully understand the characteristics of water-based adhesives

Before choosing a water-based adhesive, it is essential to fully understand its characteristics.

First of all, no adhesive is universal; an adhesive can only be used for bonding certain specific materials or types. Currently, water-based adhesives are mainly suitable for bonding between substrates such as coated paper/paper, PET/paper, BOPP/paper, PVC/paper.

Secondly, different types of water-based adhesives have different formulation methods and production processes; therefore their chemical and physical properties also vary. Printing companies should choose based on their actual situation. I believe that the important application indicators for water-based adhesives mainly include four aspects: bonding strength, high/low-temperature resistance, moisture resistance and adhesion retention. In practical applications, issues like weak bonding strength or delamination often occur due to failure to meet these four indicators.

Furthermore, it is important to understand the disadvantages of water-based adhesives including slow drying speed, poor water resistance and poor freeze resistance for reasonable usage.

2. Choose cost-effective products

When selecting a water-based adhesive, the principle should be 'quality first and price second'. An expensive product is not necessarily suitable. I believe that when choosing a water-based adhesive one should consider both the characteristics of the processed product and their own company's situation to select a product with high cost performance.

How to use water-based adhesives

1. Storage matters

Water-based adhesives must be stored in a light-proof environment at room temperature between 5-40°C with good ventilation; avoid direct sunlight exposure while preventing moisture and freezing; they must not be contaminated by dirt or solvents. It is recommended that warehouses be managed by trained personnel who keep records of temperature and humidity daily using thermometers; if temperatures exceed recommended ranges timely improvement measures should be taken to ensure quality of the adhesive. When taking out stock it should follow a first-in-first-out principle to ensure freshness.

2. Usage matters

During specific usage processes with water-based adhesives attention should be paid to the following matters.

(1) Water-based adhesives are suitable for producing lightweight composite packaging where contents are non-irritating or volatile without destructive properties; for new product structures or special packaging materials/conditions small sample trials must be conducted before large-scale production can commence after confirming requirements are met.

(2) Currently it is necessary for post-curing treatment with water-based adhesives in order to promote curing reactions achieving ideal composite strength.

(3) When dilution is needed according to usage requirements distilled or purified water should be used.

(4) Single-component water-based adhesives have a long shelf life; leftover glue can be added incrementally during next use while double-component ones should ideally be used up on the same day they are mixed.

(5) Surface treatment requirements for substrates bonded with water-based adhesive: Polyolefin film surface tension ≥38mN/m; polyester film ≥52mN/m; nylon film ≥46mN/m.

(6) Due to small application amounts of water-based adhesive it’s advisable to choose rollers with fine shallow mesh patterns which ensures better transfer onto films.

(7) Before using a water-based adhesive it’s essential to slowly stir it in its container for about five to ten minutes ensuring uniform mixing of various additives within it.

(8) Use reverse-rotating coating rollers whenever possible since reverse flattening rollers greatly affect product appearance; adjusting speed can help achieve better visual results.

(9) An air diaphragm pump must be used between coating troughs and buckets containing the adhesive ensuring cleanliness before use without residue from other solvents remaining inside.

(10) Set oven temperatures at either80°C、85°C、or95°C (the machine may only start once set temperatures are reached). Additionally airflow plays an important role in drying so both intake and exhaust volumes need maximizing allowing humid air removal effectively.

(11) To prevent plate blockage during downtime it's crucial that doctor blades are loosened allowing coating rollers remain immersed in adhesive while continuing rotation.

(12) To prevent bubbles caused by excessive machine speeds consider placing an ink leveling rod inside glue troughs.

(13) After usage rinse off any residual adhesive from coating rollers using just plain water followed by thorough cleaning with ethyl acetate; if blockages occur acetone may need utilized instead for cleaning purposes.

Operators at printing companies using these types of products must familiarize themselves thoroughly with their properties while being proactive about summarizing experiences maximizing benefits derived from them! The rapid development within this sector drives steady growth across national economies—China transitions from being merely ‘a major player’ towards becoming ‘a strong contender’ globally! Tackling VOC emissions remains critical challenge hindering progress thus requiring firms adopt sense responsibility integrating ‘green’ principles into management practices selecting eco-friendly materials together building our sustainable future.