Low-voc environment-friendly concave printing cleaning agent and preparation method thereof

Abstract

The application discloses a low-VOC environment-friendly gravure cleaning agent and a preparation method thereof. The low-VOC environment-friendly gravure cleaning agent is composed of the following components in percentage by mass: 80-90% of C10-C13 branched isomeric alkanes with a closed cup flash point of 60-90 DEG C, and 20-10% of dipropylene glycol butyl ether, and the sum of the two components is 100%. The preparation method comprises the following steps: under normal temperature and pressure, the two raw materials are sequentially put into a stirring container, and are uniformly stirred at a constant speed for 20-30 minutes until they are uniformly mixed. The application has the beneficial effects that the penetration and stripping effects of the isomeric alkanes and the strong dissolving and swelling capacity of the dipropylene glycol butyl ether are utilized, and the synergistic effect is achieved through a specific matching interval. The obtained cleaning agent has a VOC emission concentration of less than or equal to 300 mg / m3, a closed cup flash point of more than or equal to 60 DEG C, a cleaning efficiency of more than or equal to 96%, and no white spots and no watermark residues on the surface of a workpiece after cleaning. Meanwhile, the cleaning agent has the advantages of environmental protection compliance, high safety and excellent cleaning performance, solves the industry pain points of the traditional cleaning agent, such as VOC over standard, low flash point and poor ink removal effect, and has a simple preparation process and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of industrial cleaning agent technology, and in particular to a low-VOC environmentally friendly gravure printing cleaning agent and its preparation method. Background Technology

[0002] In existing technologies, gravure printing is widely used in packaging printing, publishing printing and other fields. The inks used in the printing process are mostly solvent-based or UV-based inks. When changing colors, maintaining equipment and cleaning during shutdown, it is necessary to thoroughly clean the ink and oil stains adhering to the surface of components such as ink rollers and ink troughs. At present, the cleaning agents commonly used in the industrial field mostly use highly volatile organic solvents such as tetrachloroethylene, toluene, xylene and acetone as the main components. Although these traditional solvents have strong cleaning power and fast evaporation speed, their fatal flaw is that the emission concentration of volatile organic compounds (VOCs) is extremely high, which not only seriously endangers the health of workers, but also causes serious air pollution to the environment.

[0003] To control atmospheric volatile organic compound (VOC) pollution, some regions have issued and implemented stringent local environmental protection standards, which clearly stipulate that the VOC emission limit for industrial organic solvent processes is ≤300 mg / m³. This limit has become a mandatory access requirement for relevant industries. However, actual measurements show that the real-time VOC emission concentration of conventional organic solvent cleaning agents under gravure printing cleaning conditions is generally as high as 800-1500 mg / m³, far exceeding the above-mentioned standard limit. This makes it impossible to meet the compliance emission requirements, and enterprises face a huge risk of production shutdown for rectification or heavy fines.

[0004] In response to the problem of excessive VOC emissions, some low-VOC improvement solutions have emerged in the industry. For example, simply replacing traditional low-boiling-point solvents with high-boiling-point solvents can reduce evaporation. However, such solutions have revealed several drawbacks in practical applications: if only high-boiling-point solvents are used, although VOC emissions are reduced, the solvent evaporates very slowly on the workpiece surface after cleaning, severely slowing down the production cycle and often leaving watermarks, white spots, and other residues, affecting the quality of subsequent printing; if some highly soluble components are introduced to improve cleaning power, it often leads to a sharp drop in the flash point of the system, posing a great fire safety hazard; if the content of active solvents is reduced in pursuit of high flash point and low VOC, the ability to dissolve and swell thick and stubborn gravure inks is severely insufficient, and the cleaning efficiency cannot meet the requirements of industrial production.

[0005] Therefore, the industry urgently needs a gravure printing cleaning agent that can simultaneously meet all of the following conditions: (1) Under gravure printing cleaning conditions, the ambient atmospheric VOC emission concentration is stable at ≤300 mg / m³, meeting the stringent environmental protection standards of some regions; (2) It has a high closed-cup flash point, high safety in use, and no fire hazard; (3) It has strong cleaning ability for gravure printing inks and heavy oil stains, and high cleaning efficiency; (4) It has a moderate and uniform evaporation rate, leaving the workpiece surface clean and residue-free after cleaning. However, existing technologies have consistently failed to provide such a cleaning agent with a comprehensive balance of performance in all aspects, and this contradiction has become a technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a low-VOC environmentally friendly gravure printing cleaning agent and its preparation method.

[0007] To achieve the above objectives, the technical solution proposed by this invention is as follows: A low-VOC, environmentally friendly gravure printing cleaning agent, composed of the following components by weight percentage: 80%–90% of C10–C13 branched isoalkanes, wherein the closed-cup flash point of the C10–C13 branched isoalkanes is 60°C–90°C; Dipropylene glycol butyl ether 20%–10%; The sum of the mass percentages of the two components is 100%.

[0008] The C10-C13 branched isoalkanes comprise 85% by mass, and the dipropylene glycol butyl ether comprises 15% by mass.

[0009] The mass percentage of the C10-C13 branched isoalkanes is 80%, and the mass percentage of dipropylene glycol butyl ether is 20%.

[0010] The mass percentage of the C10-C13 branched isoalkanes is 90%, and the mass percentage of dipropylene glycol butyl ether is 10%.

[0011] Under gravure printing cleaning conditions, the concentration of VOC emissions from the surrounding atmosphere is ≤300 mg / m³.

[0012] The cleaning agent has a cleaning efficiency of ≥95% for gravure inks.

[0013] After cleaning the workpiece with the cleaning agent, there are no white spots or watermarks left on the workpiece surface.

[0014] A method for preparing the low-VOC environmentally friendly gravure printing cleaning agent includes the following steps: Under normal temperature and pressure, the C10-C13 branched isoalkanes and dipropylene glycol butyl ether are sequentially added to a stirring container according to the specified ratio, and stirred at a uniform speed for 20-30 minutes until they are evenly mixed to obtain the final product.

[0015] The stirring time is 25 minutes.

[0016] The beneficial effects of this invention are: I. Under gravure printing cleaning conditions, the VOC emission concentration in the surrounding atmosphere is stably controlled within the range of 150-270 mg / m³. This not only fully meets the VOC emission limit of ≤300 mg / m³ for industrial organic solvent processes in some regions' current mandatory standards, but also leaves sufficient safety margin. It fundamentally solves the fatal pain point of traditional cleaning agents with VOC emissions as high as 800-1500 mg / m³, which prevents enterprises from producing in compliance with regulations, and provides enterprises with environmental protection technology support for sustainable operation. Second, the product's closed-cup flash point is consistently maintained above 60℃, which is significantly higher than that of traditional ketone, benzene, and ester cleaning agents. It is a high flash point safety product, which greatly reduces the risk of fire and explosion in the high-temperature and limited-ventilation conditions of the gravure printing workshop, effectively protecting the safety of operators and the safety of corporate assets. Third, through the synergistic mechanism of isoparaffin penetration and stripping and dipropylene glycol butyl ether dissolution and swelling, this cleaning agent achieves a cleaning efficiency of over 96% for gravure inks, especially for thick, long-term dried and cured stubborn inks, which can still achieve a cleaning efficiency of over 99%, completely changing the predicament of existing low VOC solutions that "meet environmental standards but cannot clean thoroughly". Fourth, the evaporation process of the cleaning agent is stable and uniform, without the "whitening" phenomenon caused by severe surface drying, and without the "watermark" or "oil spot" problems caused by excessive residue of high boiling point components. After cleaning, the surface of the workpiece is as smooth as before, and it can be directly put into the next printing cycle without secondary rinsing, which significantly improves work efficiency and printing quality. V. The preparation process only requires stirring at room temperature and pressure for 20 to 30 minutes. It does not require heating, pressurization, reflux or other complex synthesis processes. It has extremely low energy consumption, requires little equipment investment, and the raw materials are bulk industrial chemicals with stable supply and controllable costs. It is easy to achieve large-scale continuous industrial production. VI. It completely solves the common technical problem in the industry that traditional cleaning agents cannot simultaneously take into account environmental protection, safety and efficiency. Its large-scale promotion and application can significantly reduce the total VOC emissions in the gravure printing industry, help prevent air pollution and achieve the "dual carbon" goal, and has outstanding environmental and social benefits. Detailed Implementation

[0017] The present invention will now be described in further detail. A low-VOC, environmentally friendly gravure printing cleaning agent, composed of the following components by weight percentage: 80%–90% C10–C13 branched isoalkanes, with a closed-cup flash point of 60°C–90°C; 20%–10% dipropylene glycol butyl ether; the sum of the mass percentages of the above two components is 100%.

[0018] In all the following examples and comparative examples, the C10-C13 branched isoalkanes used are commercially available products with a closed-cup flash point of 60°C to 90°C. Their typical carbon number distribution is between C10 and C13, mainly containing isoalkanes and a small amount of cycloalkanes. For example, closed-cup flash points typically between 60°C and 75°C can be used, or other similar branched isoalkan solvents that meet this flash point range can be selected. Dipropylene glycol butyl ether is a commercially available industrial-grade product with a purity of ≥99%. All raw material components used can be purchased through open commercial channels.

[0019] Preparation method of cleaning agent: Under normal temperature and pressure, accurately weigh C10-C13 branched isoalkanes and dipropylene glycol butyl ether according to the predetermined mass percentage, put the two raw materials into the stirring container in sequence, start stirring, and keep stirring at a uniform speed for 20-30 minutes to make the components fully miscible and mixed evenly. Then let it stand to defoam, and a colorless and transparent finished cleaning agent can be obtained. The whole process does not require heating, pressurization or special equipment. The process is safe and reliable and suitable for large-scale mass production.

[0020] This cleaning agent is used to clean the ink rollers and / or ink tanks of a gravure printing machine by wiping or soaking.

[0021] This cleaning agent is used for cleaning stains from gravure printing ink.

[0022] Example 1:

[0023] According to the mass percentage, 85% of C10-C13 branched isoalkanes with a closed-cup flash point of 68℃ and 15% of dipropylene glycol butyl ether were used. Under normal temperature and pressure, the two raw materials were added to a mixing tank in sequence and stirred at a speed of 120 rpm for 25 minutes. After mixing evenly, the mixture was allowed to stand to defoam, and cleaning agent sample 1 was obtained.

[0024] Example 2:

[0025] According to the mass percentage, 80% of C10-C13 branched isoalkanes with a closed-cup flash point of 68℃ and 20% dipropylene glycol butyl ether were used. The same room temperature stirring process as in Example 1 was adopted, and the mixture was stirred for 25 minutes. After being mixed evenly, cleaning agent sample 2 was obtained. The dipropylene glycol butyl ether content in this ratio is relatively increased, which makes the cleaning effect more prominent for thick and stubborn gravure inks.

[0026] Example 3:

[0027] According to the mass percentage, take 90% of C10-C13 branched isoalkanes with a closed-cup flash point of 68℃ and 10% of dipropylene glycol butyl ether. Use the same room temperature stirring process as in Example 1, stir for 25 minutes, and after mixing evenly, obtain cleaning agent sample 3. This ratio has a higher flash point and a more gradual evaporation rate, and is especially suitable for cleaning common daily oil stains.

[0028] Comparative Example 1: It uses 100% C10-C13 branched isoalkanes as cleaning agents, with a closed-cup flash point of 68°C, and does not contain dipropylene glycol butyl ether.

[0029] Comparative Example 2: It uses 100% dipropylene glycol butyl ether as a cleaning agent and does not contain isoparaffins.

[0030] Comparative Example 3: According to the mass percentage, use 75% C10-C13 branched isoalkanes and 25% dipropylene glycol butyl ether, and the mixing process is the same as in Example 1.

[0031] Comparative Example 4: According to the mass percentage, use 95% C10-C13 branched isoalkanes and 5% dipropylene glycol butyl ether, and the mixing process is the same as in Example 1.

[0032] Performance testing methods: The samples obtained from the above embodiments and comparative examples were subjected to key performance tests using the following methods: 1. VOC emission concentration: In accordance with relevant environmental protection standards, the peak concentration of VOCs in the surrounding atmosphere during the cleaning operation was measured using a real-time VOC detector in a test chamber simulating gravure printing cleaning operations. The unit is mg / m³, expressed as carbon.

[0033] 2. Closed-cup flash point: Determined according to GB / T 261 standard, unit: °C.

[0034] 3. Cleaning efficiency: Preparation of standard contaminated test pieces—On a 100mm×50mm stainless steel plate, a quantitative amount of gravure solvent-based ink is uniformly coated, dried and cured at 80℃ for 2 hours, and the weight is recorded. A quantitative amount of cleaning agent is used to wet a lint-free cloth, and the test piece is wiped back and forth in a straight line 30 times under constant pressure. After cleaning, it is dried and weighed again. Cleaning efficiency = (mass of ink before cleaning - mass of residual ink after cleaning) / mass of ink before cleaning × 100%.

[0035] 4. Residue status: Visually inspect the surface of the test piece after cleaning for any white spots, watermarks, or oil film residue.

[0036] Performance test results: The obtained test data are summarized in Table 1 below.

[0037] Table 1. Performance test results of each embodiment and comparative example

[0038] Results analysis: As shown in Table 1, the cleaning agents of Examples 1-3 of this invention have VOC emission concentrations significantly lower than 300 mg / m³, stably meeting the mandatory environmental protection requirements of some regions. Their closed-cup flash points are all above 60℃, demonstrating good safety in use. The cleaning efficiency exceeds 96%, and the workpiece surface is clean and residue-free after cleaning. Particularly noteworthy is the synergistic effect between the two components within a specific ratio range of 80%–90% isoalkanes and 20%–10% dipropylene glycol butyl ether: the isoalkanes provide excellent wetting and penetration properties and a safe volatile matrix, allowing the ink to be quickly peeled off from the substrate surface and evaporated uniformly; while the dipropylene glycol butyl ether, with its strong dissolving and swelling ability for ink resins, completely dissolves the peeled ink and regulates the overall evaporation rate. Under this ratio, the two components achieve a perfect balance of performance, realizing the unity of "low VOC, high flash point, strong cleaning, and no residue."

[0039] In contrast, in Comparative Example 1, although pure isoalkanes exhibited superior VOC and flash point performance, their ability to dissolve and swell inks was severely insufficient, resulting in extremely low cleaning efficiency and failing to meet the requirements of industrial cleaning conditions. In Comparative Example 2, although the pure dipropylene glycol butyl ether had a low VOC emission concentration and a qualified flash point, its slow evaporation led to severe watermark-like residues on the surface after cleaning, and the excessively long drying time significantly affected production cycle and performance. In Comparative Example 3, the dipropylene glycol butyl ether content exceeded 20%, resulting in extremely high cleaning power, but the VOC emission concentration was approaching the limit of 268 mg / m³, the closed-cup flash point was significantly reduced to 58℃, safety decreased, and slight residues began to appear. In Comparative Example 4, the dipropylene glycol butyl ether content was less than 10%, resulting in a sharp drop in cleaning efficiency to 82.8%, and its ability to remove stubborn inks was clearly insufficient. This fully demonstrates that the specified ratio range of this technical solution has critical significance and has achieved unexpected synergistic technical effects.

[0040] Regarding the preparation method, the stirring time of 20 to 30 minutes specified in this technical solution can ensure that the two components are completely miscible and homogenized. The above embodiments all use a stirring time of 25 minutes. Actual verification shows that stirring for 20 minutes can achieve uniform mixing, while stirring for 30 minutes does not change the effect. A uniform and transparent cleaning agent product can be obtained. The entire preparation process is carried out at room temperature and pressure, and the process operation is extremely simple.

[0041] Working principle: C10–C13 branched isoalkanes possess low surface tension and excellent wetting and penetrating properties. When the cleaning agent comes into contact with the surface of gravure ink stains, the isoalkane molecules rapidly penetrate along the interface between the ink layer and the metal substrate, disrupting the adhesion between the ink resin and the substrate. This causes the ink film to be "peeled" and "lifted" from the substrate surface. In this stage, the isoalkanes primarily function as physical penetrating and peeling agents, creating contact area for subsequent deep dissolution. The ink fragments and particles loosened by the isoalkanes are then exposed to the action range of dipropylene glycol butyl ether. Dipropylene glycol butyl ether, as a low-VOC, high-boiling-point solvent with strong dissolving and swelling capabilities, has ether bonds and hydroxyl groups in its molecular structure that have a strong affinity for resin binders commonly found in gravure inks, enabling it to rapidly swell and dissolve the ink resin. The lipid skeleton completely transforms the detached solid ink fragments into a liquid dispersion that can be wiped away or rinsed off. After cleaning, the thin layer of cleaning agent remaining on the workpiece surface enters the evaporation stage. The evaporation rate of isoalkanes is relatively uniform and moderate, providing a basic safe evaporation matrix for the system. Dipropylene glycol butyl ether has extremely low volatility, but its content is strictly controlled within the range of 10% to 20%. The vapor pressures of the two are complementary under this ratio. Isoalkanes evaporate first, taking away most of the liquid and avoiding the long-term retention of a large number of high-boiling-point components. Dipropylene glycol butyl ether delays the end of the overall evaporation curve, ensuring that the solvent dissolved in the ink has sufficient open time to be wiped away, preventing the ink from drying and becoming sticky due to excessive evaporation. Together, the two stabilize the total concentration of the gaseous solvent at any given time at 300%. For C10-C13 branched isoalkanes with a concentration below mg / m³, the closed-cup flash point is strictly limited to the range of 60°C to 90°C, which falls into the category of high-flash-point flammable liquids. Dipropylene glycol butyl ether has a closed-cup flash point of approximately 100°C to 113°C and is itself a high-flash-point solvent. When the two are mixed according to the proportions of this invention, the closed-cup flash point of the mixed system is always maintained above 60°C. Under normal temperature or even high-temperature operating conditions in summer, the vapor concentration above the liquid surface is extremely difficult to reach the lower explosive limit, which essentially ensures the fire safety of industrial cleaning operations.

[0042] The beneficial effect of this invention is that, under gravure printing cleaning conditions, the VOC emission concentration in the surrounding atmosphere is stably controlled within the range of 150–270 mg / m³. This not only fully meets the current mandatory standards in some regions that require VOC emissions from industrial organic solvent processes to be ≤300 mg / m³, but also leaves sufficient safety margin, fundamentally solving the problem of traditional cleaning agents emitting VOCs as high as 800–1500 mg / m³. Addressing the critical pain point of enterprises' inability to produce in compliance with regulations, this product provides environmentally friendly technical support for sustainable operation. Its closed-cup flash point remains consistently above 60℃, significantly higher than traditional ketone, benzene, and ester cleaning agents, classifying it as a high-flash-point safe product. In the high-temperature, limited-ventilation conditions of gravure printing workshops, it greatly reduces the risk of fire and explosion, effectively protecting operator safety and enterprise assets. Through a synergistic mechanism of isoparaffin penetration and stripping combined with dipropylene glycol butyl ether dissolution and swelling, this cleaning agent achieves a cleaning efficiency of over 96% for gravure inks, especially for thick, long-term dried and cured stubborn inks, still achieving a cleaning efficiency of over 99%, completely changing the predicament of existing low-VOC solutions that "meet environmental standards but don't clean effectively." The cleaning agent's evaporation process is stable and uniform, without severe surface drying. It avoids the "whitening" phenomenon caused by excessive high-boiling-point components and the "watermark" and "oil stain" problems. After cleaning, the surface of the workpiece is as smooth as before, and it can be directly put into the next printing cycle without secondary rinsing, which significantly improves the efficiency of operation and the quality of printed products. The preparation process only requires stirring at room temperature and pressure for 20 to 30 minutes. There is no need for heating, pressurization, reflux or other complex synthesis processes. The energy consumption is extremely low, the equipment investment is small, the raw materials are bulk industrial chemicals, the supply is stable, the cost is controllable, and it is easy to realize large-scale continuous industrial production. It completely solves the common technical problem in the industry that traditional cleaning agents cannot simultaneously take into account environmental protection, safety and efficiency. Its large-scale promotion and application can significantly reduce the total VOCs emissions in the gravure printing industry, help the prevention and control of air pollution and the achievement of the "dual carbon" goal, and has outstanding environmental and social benefits.

[0043] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A low-VOC environmentally friendly gravure printing cleaning agent, characterized in that, It consists of the following components by mass percentage: 80%–90% of C10–C13 branched isoalkanes, wherein the closed-cup flash point of the C10–C13 branched isoalkanes is 60°C–90°C; Dipropylene glycol butyl ether 20%–10%; The sum of the mass percentages of the two components is 100%.

2. The low-VOC environmentally friendly gravure printing cleaning agent as described in claim 1, characterized in that, The C10-C13 branched isoalkanes comprise 85% by mass, and the dipropylene glycol butyl ether comprises 15% by mass.

3. The low-VOC environmentally friendly gravure printing cleaning agent as described in claim 1, characterized in that, The mass percentage of the C10-C13 branched isoalkanes is 80%, and the mass percentage of dipropylene glycol butyl ether is 20%.

4. The low-VOC environmentally friendly gravure printing cleaning agent as described in claim 1, characterized in that, The mass percentage of the C10-C13 branched isoalkanes is 90%, and the mass percentage of dipropylene glycol butyl ether is 10%.

5. The low-VOC environmentally friendly gravure printing cleaning agent as described in any one of claims 1-4, characterized in that, Under gravure printing cleaning conditions, the concentration of VOC emissions from the surrounding atmosphere is ≤300 mg / m³.

6. The low-VOC environmentally friendly gravure printing cleaning agent as described in any one of claims 1-4, characterized in that, The cleaning agent has a cleaning efficiency of ≥95% for gravure inks.

7. The low-VOC environmentally friendly gravure printing cleaning agent as described in any one of claims 1-4, characterized in that, After cleaning the workpiece with the cleaning agent, there are no white spots or watermarks left on the workpiece surface.

8. The method for preparing the low-VOC environmentally friendly gravure printing cleaning agent according to any one of claims 1-7, characterized in that, Includes the following steps: Under normal temperature and pressure, the C10-C13 branched isoalkanes and dipropylene glycol butyl ether are sequentially added to a stirring container according to the specified ratio, and stirred at a uniform speed for 20-30 minutes until they are evenly mixed to obtain the final product.

9. The preparation method of a low-VOC environmentally friendly gravure printing cleaning agent as described in claim 8, characterized in that, The stirring time is 25 minutes.

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