Hair prickling, missed printing, graphic and textual flower spots How to effectively solve printing static electricity?

In the modern printing industry, with the continuous development of printing technology and the increasing speed of printing, static electricity problems have become increasingly prominent, bringing many troubles to the printing process, seriously affecting printing quality and production efficiency, and even posing a threat to production safety. Therefore, conducting in-depth research on the impact of static electricity on printing and exploring effective solutions is of great significance for the development of the printing industry.
The impact of static electricity on printing
01/Impact on Printing Quality
(1) Fuzzy prick
When printing graphic and text parts, solid parts, or large characters with thick lines, due to static electricity, there will be ink splashing in the form of hairs, resulting in a linear ink phenomenon resembling a "beard". This is because during the printing process, ink particles carry static electricity and repel each other, resulting in uneven transfer of ink to the substrate and the formation of burrs at the edges of the text, seriously affecting the clarity and aesthetics of the printed product. For example, in some packaging printing, the text and patterns on the surface of the product may have burrs, which can lower the product's grade and market competitiveness.
(2) Missing print
During the printing process, some graphics and text cannot be printed or printed properly due to static electricity, resulting in missed printing; When laying white ink on the bottom, there may be a phenomenon of repulsion, causing gaps. This is because the static electricity on the surface of the substrate will generate a repulsive force on the ink, hindering the normal transfer of ink and preventing the complete printing of the graphic and textual parts. For example, in label printing, if there is a missing print, it will result in incomplete label information, affecting product recognition and sales.
(3) Graphic and textual highlights
Static electricity can cause dust and impurities to adsorb onto printing materials such as films, resulting in many uneven dots on graphics and text after printing. These dots will disrupt the integrity and consistency of the graphics and reduce the quality of the printed material. In high-end brochure printing, the appearance of graphic and textual dots can seriously affect the texture and artistic effect of the picture.
(4) Tears like water droplets
During full page printing, water droplets resembling "tears" appear in multi-color overlay printing, some light and some heavy. This is due to the uneven distribution of ink on the surface of the substrate caused by static electricity, resulting in ink aggregation and the formation of water droplets, which affects the color uniformity and saturation of printed materials. In poster printing, these "tear like" water droplets can distort the color of the image and fail to achieve the expected promotional effect.

02/ Impact on production safety
During the printing process, strong static electricity is generated due to high-speed friction and peeling. When static electricity accumulates to a certain extent, it can easily cause air discharge, resulting in electric shock or fire. For example, in environments where ink and solvents evaporate, charged ink or substrates may cause fires, posing a serious threat to the personal safety of operators and the property safety of enterprises. At the same time, electrostatic shock can also startle operators, affect work efficiency, and even lead to operational errors, causing other safety accidents.
03/Impact on Production Efficiency
When paper has static electricity, charges of the same polarity repel each other, which can cause inaccurate positioning of the paper feeding and affect the stacking of paper on the overprint and delivery platforms; And the mutual attraction of different charges can cause the paper and printing equipment to attract each other, resulting in difficulties in paper feeding, uneven paper delivery, and inaccurate overprinting, leading to production interruptions and delays. On automated printing production lines, these problems frequently occur, requiring operators to constantly stop and adjust, seriously reducing production efficiency. In addition, static electricity can cause materials to adhere to the transmission rollers and guide rollers, affecting printing and die-cutting alignment, further reducing production efficiency.
Reasons for static electricity generation
01/Material properties
The conductivity of materials has a dual effect on static electricity. If the material is a conductor, the charge can move freely and be evenly distributed on its surface, which can only cause lower voltage, and the conductive material can transfer the charge to the ground when in contact with it; And insulating materials such as paper, plastic film, etc. generate high voltage after static electricity, and cannot be eliminated by grounding. The chemical composition, internal structure, stress-strain mechanical characteristics, and shape of materials can also affect the generation of static electricity. For example, different types of paper produce varying degrees of static electricity due to differences in their fiber structure and chemical composition. For example, plastic films with smooth surfaces are more likely to generate static electricity than those with rough surfaces.
02/Mechanical action
Mechanical action includes the type of contact between two materials, time, area, separation speed, and properties of material forces. In general, the tighter the contact or faster the separation speed between two materials, the greater the static electricity generated. During the printing process, paper frequently comes into contact with and separates from components such as rollers and guides of printing equipment. Especially during high-speed printing, the separation speed is fast and a large amount of static electricity is easily generated. In addition, uneven printing pressure can also lead to different friction and contact between materials, thereby affecting the generation of static electricity.
03/Ink characteristics

The composition and properties of ink can also affect the generation of static electricity. Some inks contain volatile solvents, which evaporate during the printing process, causing changes in the conductivity of the ink and easily generating static electricity. The viscosity and fluidity of ink can also affect the generation of static electricity. Ink with high viscosity has high friction during transfer and is prone to static electricity; Ink with good fluidity may also generate static electricity due to friction with pipes and components when flowing in the ink fountain and ink path.
04/Environmental factors
Temperature and humidity have a close impact on static electricity generation. Paper is stored in the paper warehouse and workshop, and due to significant differences in temperature and humidity, the moisture content changes noticeably. Once the relative humidity of the air drops to a certain level (below 40%), static electricity is easily generated; When the ambient temperature rises, the paper is subjected to friction, and the movement of electric charges accelerates, leading to an increase in the generation and accumulation of static electricity. In the dry and cold environment of winter, the static electricity problem in the printing workshop is often more prominent. In addition, dust and impurities in the environment can also affect the generation and accumulation of static electricity. Dust adsorbed on the surface of the substrate may alter its surface charge distribution, thereby exacerbating static electricity phenomena.
Solution to static electricity
01/Physical elimination method
(1) Grounding
Connecting printing equipment and metal conductors to the ground creates a potential difference between the object and the ground, allowing charges to leak through the ground. This is the simplest physical method of eliminating static electricity, but it has almost no effect on insulators. In the printing workshop, it is necessary to ensure good grounding of the equipment, regularly check the grounding circuit and grounding resistance, and generally require the grounding resistance to be less than 10 Ω. For example, connecting the metal frame, ink fountain, guide roller and other components of the printing machine to the ground through grounding cables, so that static electricity on the equipment can be promptly introduced into the ground.
(2) Adjust humidity
The surface resistance of printing materials decreases as the relative humidity of the air increases. Increasing the relative humidity of the air can improve the conductivity of the paper surface and accelerate charge leakage. Generally speaking, the relative humidity in the printing workshop should be controlled between 40% and 60%. The humidity in the workshop can be adjusted by installing humidifiers or dehumidifiers. During the dry season, use a humidifier to increase air humidity; In humid seasons, use dehumidifiers to reduce air humidity to maintain a suitable printing environment.
(3) Static eliminator

Induction type static eliminator, also known as induction type static eliminator brush, works by inducing charges with opposite polarity to the static electricity on the charged body when the tip of the eliminator approaches the charged body, and forming a strong electric field near the tip. This electric field ionizes the air and produces positive and negative ions that move towards the charged body and the tip of the eliminator under the action of the electric field, thereby neutralizing static electricity. During the printing process, a combination of induction and high-voltage discharge static electricity elimination methods can be used. The static electricity eliminator can be installed in the paper feeding area, near the printing drum, and at the paper receiving area of the printing machine, which are prone to static electricity, to completely and effectively eliminate static electricity.
02/Chemical elimination method
The chemical elimination method generally involves coating a layer of anti-static agent on the surface of the printing material to make it conductive. However, due to the addition of chemical components to paper during papermaking, it may have adverse effects on the quality of the paper, such as reducing its strength, adhesion, tightness, tensile strength, etc. Therefore, it is generally not commonly used. For printing materials such as plastic film, suitable anti-static agents can be selected for treatment. When choosing anti-static agents, the type and amount of anti-static agent should be determined based on the characteristics of the material and printing requirements to avoid affecting other properties of the material.
03/Optimize production process and management
Reasonably arrange the process flow, avoid long-term material stacking and friction, and reduce static electricity accumulation. For example, wet the paper before printing to ensure uniform and stable moisture content; During the printing process, control the printing speed and pressure to avoid static electricity caused by excessive speed and pressure; Provide static electricity protection training to employees to enhance their awareness of static electricity hazards and safety operation consciousness; Develop detailed operating procedures to regulate employees' behavior during the printing process, such as avoiding direct contact with the substrate and ink by hand, and preventing static electricity generated by friction; Regularly inspect and maintain the equipment to ensure its normal operation and avoid static electricity caused by equipment malfunctions.
Case Analysis
A large printing enterprise encountered serious quality problems in the production of high-end food packaging boxes due to static electricity issues, such as graphic burrs, missing prints, and flower spots, resulting in a large number of scrapped products and severe economic losses. At the same time, static electricity also caused several small-scale fires. Although they were promptly extinguished, they posed great risks to the production safety of the enterprise.
After investigation and analysis, it was found that the humidity in the printing workshop of the enterprise is relatively low, with an average relative humidity of around 30%, and there are problems with the grounding system of the printing equipment, with some equipment having excessive grounding resistance. In addition, the quality of the paper and ink used is unstable and prone to static electricity.

In response to these issues, the company has taken a series of measures:
Firstly, a humidifier was installed to increase the relative humidity in the workshop to around 50%;
Secondly, a comprehensive inspection and maintenance were conducted on the grounding system of the printing equipment to ensure that the grounding resistance meets the requirements;
In addition, more stable quality paper and ink have been replaced, and employees have received training on electrostatic protection knowledge and standardized operating procedures.
Through the implementation of these measures, the static electricity problem of the enterprise has been effectively solved, the printing quality has been significantly improved, production safety has been guaranteed, the scrap rate has been significantly reduced, and production efficiency has been significantly improved.
The impact of static electricity on the printing industry is multifaceted, not only reducing printing quality and affecting product market competitiveness, but also threatening production safety and lowering production efficiency. Understanding the causes of static electricity, such as material properties, mechanical effects, ink characteristics, and environmental factors, is crucial for taking effective solutions. By comprehensively utilizing physical elimination methods, chemical elimination methods, and optimizing production processes and management, the generation and harm of static electricity can be effectively reduced, ensuring the smooth progress of printing production and improving the quality and economic benefits of printed materials. In future printing production, with the continuous advancement of technology, printing enterprises should constantly explore and apply more advanced electrostatic protection technologies to cope with increasingly complex printing production environments and higher quality requirements.