How does liquid photopolymer achieve a balance between flexibility and fine image quality in corrugated cardboard printing?
Publish Time: 2025-12-09
In the packaging printing industry, corrugated cardboard is widely used due to its lightweight, pressure-resistant, and environmentally friendly properties. However, its rough surface and uneven structure present significant challenges for printing. Traditional rigid printing plates easily cause dot loss, uneven ink coverage, and even cardboard crushing, while overly flexible plates struggle to reproduce fine images. Liquid photopolymer was developed to address this need—through its unique material formulation and photopolymerization process, it has found a delicate balance between "ultimate flexibility" and "high-precision imaging," making it an ideal choice for thick flexible printing plates.
1. Low rigidity provides excellent adhesion, adapting to the complex surface of corrugated cardboard
Corrugated cardboard is made by bonding face paper, core paper, and liner paper together, resulting in natural ripples and minor unevenness on its surface. If a high-rigidity printing plate is used, it cannot fully adhere to the paper surface under printing pressure, causing some areas of the image to "hang," resulting in missed prints or light ink coverage. Printing plates made of liquid photopolymer, with a Shore A hardness of only 25, possess a silicone-like softness and elasticity. They can naturally deform along the contours of the cardboard under extremely low printing pressure, ensuring uniform contact between the entire image area and the substrate. This "softness overcomes roughness" characteristic effectively avoids the risk of crushing the corrugated structure while ensuring consistent ink transfer, making it particularly suitable for high-quality printing on fine or micro-corrugated cardboard such as E and F.
Flexibility does not come at the expense of precision. During ultraviolet light exposure, the polymerization reaction area of liquid photopolymer is controlled directly through digital imaging film or laser plate making. Unexposed areas are developed and washed away, forming a precise embossed structure. Thanks to the high photosensitivity and low viscosity fluidity of the resin system, even when creating printing plates 3–6 mm thick, it can clearly reproduce fine lines below 0.1 mm, small text, and high-line-count dots. Sharp edges and a vertically oriented embossed structure ensure clear ink transfer boundaries, effectively suppressing "smudging" or "ink spread," making key information such as brand logos, barcodes, and product descriptions clearly legible.
3. Synergistic Optimization of Material Formulation: Flexibility with Toughness, Balancing Printing Life
Simply being soft can lead to rapid wear or deformation of printing plates during high-speed printing. To address this, modern liquid photopolymer utilizes a scientifically formulated blend of multifunctional prepolymers, nano-reinforcing fillers, and crosslinking agents to improve cohesive strength and abrasion resistance while maintaining low hardness. The cured printing plate is not only flexible and conforms well but also possesses excellent tear resistance and resilience—quickly returning to its original shape after each impression, avoiding permanent deformation. This allows a single printing plate to stably complete hundreds of thousands of printing cycles, significantly superior to traditional rubber plates, reducing plate-making costs and downtime for plate changes.
4. Strong Process Adaptability, Supporting Efficient and Green Production
The liquid photopolymer plate-making process is compatible with mainstream flexographic plate-making equipment, automating the entire process from exposure and development to post-curing. Its water-washing or environmentally friendly solvent developing process aligns with current green printing trends. More importantly, due to the flexible printing plate and low required printing pressure, damage to the corrugated cardboard structure is reduced, lowering the scrap rate; simultaneously, low-pressure operation reduces the load on the printing press rollers, extending equipment life.
The success of liquid photopolymer in corrugated cardboard printing stems from the ingenious reconciliation of the seemingly contradictory demands of "flexibility" and "precision." With its flexible 25A plate, it carries high-definition images and text, delivering on its printing quality promise through precise photopolymerization. In today's booming market for e-commerce packaging and high-end color boxes, this intelligent printing material, which protects the corrugated structure while showcasing brand quality, is becoming a key force driving corrugated printing towards higher quality, higher efficiency, and sustainability.
