This innovative solution is really practical.

With the establishment and implementation of China's tobacco packaging bidding system, the domestic cigarette packaging industry has gradually fallen into the predicament of 'price reduction with every bid.' Over more than a decade, industry profit margins have been continuously squeezed, and currently, tobacco printing companies are operating on a knife-edge, facing losses with even minor mistakes. Against this backdrop, many large domestic private enterprises have gradually divested from cigarette packaging printing businesses and shifted to developing new economic growth points. At the same time, professional tobacco printing enterprises under the investment companies of China National Tobacco have been striving to survive in the market gaps. In addition to continuously strengthening internal cost reduction and efficiency improvement, they have also continued the 'price reduction with every bid' strategy in raw material procurement, directly leading to intense internal competition within the domestic cigarette packaging materials industry. The continuous decline in material prices has directly caused a covert deterioration in material quality, making innovation in production processes a key approach to solving this problem. In response to the curling problem of gravure printed soft pack cigarette cartons caused by changes in material characteristics, our company has, through innovative exploration, developed a systematic solution, which we now share with industry peers in hopes of jointly promoting high-quality development of the industry.

Curling Problem of Gravure Printed Soft Pack Cigarette Cartons

The 'Furong (Soft Red)' cigarette small boxes printed by our company use 97g/m² coated paper as the base material. Due to its relatively thin thickness (about 0.09mm), this paper type has strict requirements for the physical properties of raw materials during the gravure printing process. However, affected by the 'price reduction with every bid' nature of the tobacco packaging bidding system, our previous paper supplier failed to win the bid due to compressed profit margins, and we have switched to a new supplier.

The paper from the new supplier has significant limitations in its production process: on one hand, the fiber's physical properties are insufficient, specifically showing uneven fiber length distribution and inadequate inter-fiber bonding strength, resulting in poor internal structural stability of the paper; on the other hand, the surface treatment process has shortcomings, including deviations in sizing dosage and uneven coating, reducing the paper's moisture regulation capability. The combination of these two defects ultimately causes the paper, after being cut into sheets by the gravure press, to develop periodic wavy curling deformation along the horizontal direction (as shown in Figure 1), forming a systematic impact on the entire production process. The specific issues are as follows.

01/ Production efficiency has fallen off a cliff, and the material loss rate has surged
In the gravure printing process, the severely curled paper cannot form a flat stacking state due to the edge uplifting and the wave deformation in the middle, resulting in frequent paper collection jamming: when running at high speed, the crimped paper is easy to trigger the chain reaction of "stagnation, skewedness, and paper blockage" of paper collection, with a cumulative number of paper blocking times in a single day exceeding 15 times, and each cleaning needs to be stopped for about 30 minutes, and the production efficiency plummets by about 30%; At the same time, the semi-finished paper will produce irreversible defects such as creases and tears in the process of plugging, and the material loss rate of a single batch soared from the original 0.2% to 5.1%, and the material cost increased significantly.
02/ The product qualification rate has dropped sharply, and the labor intensity has doubled
The soft pack cigarette pack needs to be cut, and the crimped paper exposes the problem of positioning loss in the cutting process: when cutting, the wavy curl makes the paper unable to fit close to the cutting platform, and the deviation between the cutting knife line and the positioning reference line is 0.4mm, resulting in the deviation of the cutting size. The amount of waste and defective products increased by nearly 8 times compared with the normal state. In order to reduce waste, the cutting personnel need to be manually flattened, and the cutting production efficiency is reduced; The finished product inspection process needs to be manually leveled, and the labor intensity of inspection is greatly improved.
03/ The packaging adaptability is completely ineffective, and the customer's operation and maintenance costs are high
Although the finished product has been treated by humidity control and cleatting, the internal fiber stress of the paper has not been fully released, and it still shows curling and deformation when loaded into the tobacco factory packaging machine. When the crimped paper enters the conveying track of the packaging machine, it directly affects the production progress of the tobacco factory. In order to ensure the normal use of trademark paper, our company had to send 3 inspectors to the site 24 hours a day to pre-treat the trademark paper by using the "manual reverse bending" method, which greatly increased the cost of customer operation and maintenance, and the brand trust faced severe challenges.
Traditional process solution trials
In order to systematically solve the above production problems, it is found that the printing industry generally has similar paper deformation problems in the production of soft packs, and the industry usually uses the back coating process of soft sheet paper for regulation. Based on this, our company has designed three coating process schemes for improvement and testing for the problem of large wavy curling after gravure printing of "hibiscus (soft red)" cigarette pack small box, as follows.
Scheme 1: Back-coating water-based varnish process
Customize a special water-based varnish coating roller, and use the reverse printing unit of the existing gravure printing machine to apply water-based varnish coating treatment on the back of the paper to enhance the water-locking performance of the paper. Coating system ratio: water-based varnish BH3000 and mixed solvent are mixed according to 1∶1 (mixed solvent is alcohol: water = 1∶2), and the drying temperature is controlled at 90~100°C.
Option 2: Water-based varnish process on the front
Customize a special water-based varnish coating roller to coat water-based varnish (ink viscosity 16±2s, drying temperature 90~100°C) in the gravure first color group, and reduce the difference in water absorption by adjusting the surface properties of the paper.
Scheme 3: Composite coating process
The above-mentioned water-based varnish on the back and water-based varnish on the front are simultaneously implemented to form a dual control system of "back coating water lock + front water control".
After the above three schemes were tested, the curling degree of the paper was only slightly improved, and it still did not meet the normal production requirements, and there was a significant gap with the expected effect. The analysis shows that the industry's conventional process scheme has achieved full coverage testing, but the back coating material is single (only BH3000 varnish) and the main coating material has not been adjusted variables in the test. To this end, the team further focused on the selection of back coating materials and designed a multi-dimensional cross-test scheme.
Scheme 1: Single variable test of backcoating materials
Two types of back-coating inks, C205 (factory A) and Q2105I (factory B), were selected to keep the coating amount, drying temperature and other parameters consistent, and the effects of different materials on the flatness of paper collection were compared and tested.
Scheme 2: Single variable test of frontal coating material
Two frontal varnishes were selected from factory C and D to keep the coating amount, drying temperature and other parameters consistent, and independently tested the regulation effect of the water absorption uniformity and paper collection flatness on the paper surface.
Scheme 3: Composite test of the front and back coating materials
The samples with better flatness in the back coating material test were selected and combined with the front varnish of factory C and D to test the inhibition effect of the composite coating system on the internal stress balance and crimping deformation of the paper.
After the above-mentioned cross-test verification of back-coating/main-coating materials, the wavy curling problem of paper has not been effectively controlled, and the traditional idea of "back-coating/main-coating material regulation" has fallen into a bottleneck. This shows that the curling problem of "Hibiscus (soft red)" cigarette packets cannot be completely solved by optimizing the coating material or process parameters alone, and it is necessary to break through the traditional technical framework and explore innovative solutions.
Thinking and analysis of innovative process solutions
In the face of the technical bottleneck of traditional coating technology and material regulation scheme, the team is deeply aware that to solve the problem of gravure curling of "hibiscus (soft red)" cigarette pack small box, it is necessary to jump out of the traditional mindset of "single material optimization" or "conventional process adjustment" and reconstruct the problem analysis framework with innovative thinking. The breakthrough of innovation is often hidden in the deep deconstruction of the details of the printing process and the structural characteristics of the product - by tracing back the whole production process data and recombing the micro links, we found that the previous analysis ignored two key systemic correlations: one is the implicit impact of pattern design on product wave deformation, and the other is the dynamic adaptation relationship between the characteristics of ink materials and printing process parameters. Based on this, the team innovatively constructed a two-dimensional analysis model of "pattern structure + material properties" to re-examine the essential causes of the curling problem from the intersection of macro design logic and micro material behavior.
01/ Pattern structure characteristics
According to the pattern structure characteristics of this soft pack cigarette pack, the pattern is distributed in strips after the large version, and there is a certain similarity between the product wave deformation law and the pattern arrangement law, which provides a new thinking direction for solving the wave deformation of the product.
02/ Paper ink characteristics
After analyzing the paper and ink types used in soft packs, it was found that there was a big problem in the matching between the physical properties of the paper of the new supplier and the existing ink. The large area ink in direct contact with the surface of the cigarette pack is mainly solvent-based red ink and water-based varnish, and the inks of the two different systems are printed on the flexible sheet paper, which will cause different deformations on the flexible sheet paper, which will cause curling problems.
The implementation and effectiveness of innovative process solutions
01/ Implement specifically
Through the in-depth analysis of the above two factors, it can be seen that the root cause of the wavy curling problem of gravure soft pouches lies in the coupling effect of the physical properties of the new supplier paper and the characteristics of the two types of inks. Based on this, we have developed the following innovative process solutions:
(1) In view of the wavy curl deformation problem caused by the difference in deformation between solvent-based ink and water-based ink in the gravure printing process, the special red ink system is converted from solvent-based to water-based, and the water-based gravure red plate is made.
(2) In view of the problem of upward warping at both ends of the paper collection, the back coating process is used to solve the warping and deformation caused by the reduction of the internal moisture of the paper after passing through the oven.
After the "Furong (Soft Red)" cigarette pack small box is produced by the new process scheme of "water-based special red + back coating", the gravure paper is flat, the paper is flat when the machine knife is cut, and the packaging adaptability of the tobacco factory is normal. The new process solution perfectly solves the curling problem of the "Hibiscus (soft red)" cigarette packet small box, and can meet the production and packaging requirements of the product and the packaging of tobacco factories.
02/ Economic benefit analysis
After adopting the new process, the printing efficiency has been increased by more than 2 times, the cutting efficiency has reached the production quota requirements, and the product qualification rate has exceeded the target output rate by 2.96%. After accounting, the cost saving of a single thousand boxes of products is about 2,960 yuan, and the annual output of 50,000 large boxes is calculated, with an annual cost saving of 148,000 yuan, achieving a double improvement in production efficiency and economic benefits
In addition, the new process completely solves the problem of frequent jamming of the packaging machine caused by the curling of cigarette packs, and the flatness of the product is better than that of the original normal supply products, and the packaging adaptability is greatly improved, which has been recognized and highly praised by the tobacco factory roll and bag workshop. This technological breakthrough not only ensures stable supply, but also more effectively enhances customer trust and significantly enhances the company's brand reputation in the field of cigarette pack printing.
In view of the problem of "hibiscus (soft red)" cigarette pack small box gravure waving and curling caused by raw material replacement, this paper breaks through the limitations of traditional process improvement, and innovatively uses the solution of "ink system substitution + back coating process coordination" through the correlation analysis of pattern structure characteristics and material physical properties, realizes the flat paper collection and precise cutting of cigarette packs, completely solves a series of problems such as low production efficiency and poor suitability of cigarette pack packaging on the machine, and has been recognized and highly praised by the roll packaging workshop. This innovative idea is expected to provide systematic solutions and practical examples for the industry to solve similar technical problems, provide a reference path for process optimization and technological innovation in the field of cigarette pack printing, and help promote the high-quality development of the industry.