An integrally formed process of high molecular electrostatic traceless self-adhesive film

Abstract

The application discloses a kind of integrally formed processes of high molecular electrostatic traceless self-adhesive film, belong to the technical field of home decoration materials, the process includes: after mixing PVC resin powder, TPR modified resin and auxiliary materials, extrusion plasticization, film is formed by calendering, high-voltage electrostatic is applied to film surface in the process of calendering simultaneously to form adsorption function layer, electrostatic film is immediately integrally embossed in the heat preservation state, after cooling and setting, slitting and winding are finished product.The application realizes the trinity of forming, electrostatic giving and embossing continuous production;At the same time, the microstructure of the pattern area changes in the embossing process, so that its holding capacity of static electricity is higher than that of non-pattern area, forming differentiated charge distribution, giving the product pattern area adsorption enhancement, overall adhesion firm and no trace of stripping characteristics, pattern and base material are the same continuous phase, which eliminates the risk of delamination.

Description

Technical Field

[0001] This invention relates to the field of home decoration materials technology, and in particular to an integrated molding process for a polymer electrostatic traceless self-adhesive film. Background Technology

[0002] Currently, window decorative films are mainly divided into two categories: self-adhesive adhesive and electrostatic adsorption. Self-adhesive adhesive products suffer from problems such as decreased adhesion after the adhesive layer ages, difficulty in peeling, and easy residue. Furthermore, the coating process involves organic solvents, posing environmental risks. While electrostatic adsorption products offer advantages such as being glue-free, residue-free, and reusable, existing products have several shortcomings: First, most window decorative films are flatly printed, lacking three-dimensional texture and limiting decorative effects; second, the few products with three-dimensional lace patterns typically employ a multi-layer composite structure—preparing a substrate layer, a pattern layer, and an electrostatic adsorption layer separately before laminating them—leading to interlayer separation due to the presence of bonding interfaces between layers over long-term use, and the lamination process is complex and involves numerous steps; third, the charge in existing electrostatic adsorption products is uniformly distributed on the film surface, failing to enhance adsorption in specific patterned areas, resulting in insufficient overall adhesion. In addition, window coverings and lace tablecloths are functionally separate, and there is no integrated product that can simultaneously meet the needs of both window coverings for adhesive application and tablecloths for flat application. Traditional fabric lace is prone to aging, fading, and has poor water resistance, while plastic window film lacks flexibility and light resistance.

[0003] To address the shortcomings of the existing technologies, there is an urgent need to develop a polymer electrostatic traceless self-adhesive film molding process that can achieve integrated continuous production of substrate molding, electrostatic imparting, and three-dimensional pattern pressing. This process would simplify the production process, improve product structural stability and adsorption performance, and simultaneously meet the application needs of both window coverings and tabletop decorations. Summary of the Invention

[0004] The main objective of this invention is to provide an integral molding process for a polymer electrostatic traceless self-adhesive film, which can effectively solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A one-piece molding process for a polymer electrostatic residue-free self-adhesive film includes the following steps: S1. Raw material preparation: Weigh 100 parts of SG-5 type PVC resin powder, 30-50 parts of TPR modified resin, 120-160 parts of calcium carbonate filler, 4-6 parts of composite stabilizer, 0.2-0.5 parts of lightfastness additive, 25-35 parts of plasticizer, and 1-3 parts of antistatic agent according to the following weight proportions, and put them into a high-speed mixer and mix evenly to obtain a mixture. S2, Extrusion Plasticization: The mixture is fed into a twin-screw extruder for melt plasticization, and then extruded through a die to obtain a plasticized melt; S3. Calendering and synchronous electrostatic treatment: The plasticized melt is fed into a calender and calendered into a continuous film substrate; during the synchronous calendering process, a high voltage electrostatic charge is applied to the surface of the film substrate by an electrostatic application device set between the rollers of the calender, so that the surface of the film substrate carries a uniform electrostatic charge and forms an electrostatic adsorption functional layer. S4. Integrated Embossing: The electrostatically charged film substrate obtained in step S3 is immediately fed into an embossing device under a heat-preserving state for integrated embossing of the lace pattern. The embossing device includes an embossing roller and a back pressure roller. The embossed pattern is pressed onto the surface of the film substrate by the engraved pattern on the surface of the embossing roller to form a three-dimensional lace pattern. During the embossing process, the patterned area and the non-patterned area have different microstructures due to the action of compressive stress and temperature field. This makes the patterned area more capable of retaining static charge than the non-patterned area, thereby forming a differentiated charge density distribution on the film surface corresponding to the lace pattern. S5. Cooling and shaping: The embossed film obtained in step S4 is cooled and shaped sequentially. S6. Slitting and winding: The cooled and shaped film is slitted and wound online according to specifications.

[0006] Preferably, the TPR modified resin in step S1 is a thermoplastic elastomer based on SEBSS hydrogenated styrene-butadiene-styrene block copolymer; the calcium carbonate filler has a particle size of 800-1500 mesh; the composite stabilizer is a calcium-zinc composite stabilizer; the lightfastness aid is a compound system of hindered amine light stabilizer and ultraviolet absorber; the plasticizer is DOP or DOTP; the high-speed mixing temperature is 110-130℃, and the mixing time is 8-15 minutes. SEBS-based TPR imparts excellent flexibility and resilience to the product, complementing PVC and overcoming the deficiency of insufficient flexibility in a single PVC system.

[0007] Preferably, in step S2, the twin-screw extruder is provided with six heating zones in sequence along the material travel direction. The temperatures of each heating zone are as follows: Zone 1 130-140℃, Zone 2 140-150℃, Zone 3 150-160℃, Zone 4 155-165℃, Zone 5 160-170℃, and Zone 6 165-175℃. The die temperature is controlled at 160-170℃. The residence time of the material in the extruder is controlled at 2-5 minutes.

[0008] Preferably, the calender in step S3 is a four-roll calender, with the four roll temperatures sequentially as follows: first roll 170-180℃, second roll 165-175℃, third roll 160-170℃, and fourth roll 155-165℃, with the roll spacing decreasing sequentially. This calenders the plasticized melt into a continuous film substrate with a thickness of 0.25-0.40mm. The electrostatic application device includes multiple discharge electrodes evenly distributed along the width of the film. The distance between the electrodes and the film surface is controlled at 5-15mm. A DC high-voltage electrostatic charge of 8-15kV is applied, causing the electrostatic voltage on the surface of the film substrate to reach -5kV to -10kV or +5kV to +10kV. The electrostatic application device is positioned between the third and fourth rolls, completing the electrostatic application during the synchronous process of film substrate forming, which differs from the prior art's approach of performing electrostatic treatment separately after substrate forming. The gradual decrease in roller temperature ensures the film is gradually shaped, while the limited electrode distribution and applied voltage guarantee the uniformity of the charge on the film surface, which is the basis for forming a stable electrostatic adsorption functional layer.

[0009] Preferably, in step S4, the heat preservation temperature of the film substrate before entering the embossing device is 70-90℃; the temperature of the embossing roller is controlled at 80-100℃, the temperature of the back pressure roller is controlled at 40-60℃, the pressing pressure is controlled at 3-8MPa, and the traveling speed of the film substrate is controlled at 25-33m / min; the depth of the lace pattern engraved on the surface of the embossing roller is 0.15-0.30mm.

[0010] Preferably, the cooling and shaping in step S5 adopts a segmented cooling method: the embossed film passes through the first cooling roller and the second cooling roller in sequence. The temperature of the first cooling roller is 50-65℃, and the temperature of the second cooling roller is 20-35℃. The linear speed of the cooling roller is synchronized with the traveling speed of the embossing device.

[0011] Preferably, in step S4, the embossing roller achieves the hollowed-out effect of the lace pattern through a scraper removal process. The embossing device also includes a scraper assembly disposed on the surface of the embossing roller to scrape off residual material in the non-patterned area of ​​the embossing roller, ensuring the clarity of the pattern transfer. Before slitting and winding in step S6, foreign matter on the film surface is removed by a dust removal device. For products that need to be stored for a long time, a PET release film with a thickness of 0.025-0.050mm is bonded to the electrostatic adsorption surface of the self-adhesive film by a laminating device before winding, and the laminating pressure is controlled at 0.5-2MPa.

[0012] A polymeric electrostatic residue-free self-adhesive film, wherein the self-adhesive film is a single-layer integral structure, comprising: The substrate layer is composed of the PVC / TPR modified resin blend; The lace pattern layer is formed directly on at least one surface of the substrate layer through the integrated embossing process. The lace pattern layer and the substrate layer are the same continuous phase and are bonded without interface. The electrostatic adsorption functional layer is composed of electrostatic charges applied during the calendering process and is distributed on the surface and near-surface area of ​​the self-adhesive film. The patterned area of ​​the lace pattern layer has a higher ability to retain static charge than the non-patterned area due to the microstructural differences generated during the embossing process. This results in a higher charge density in the patterned area compared to the non-patterned area, forming a differentiated charge density distribution corresponding to the lace pattern.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention achieves continuous production of substrate forming, electrostatic application, and three-dimensional pattern pressing by simultaneously applying electrostatics during calendering and immediately performing integrated embossing while the film is kept warm. This significantly simplifies the process and reduces equipment energy consumption. Simultaneously, the patterned areas exhibit microstructural differences due to compressive stress and temperature field during embossing, resulting in a higher ability to retain electrostatic charge compared to non-patterned areas. This creates a differentiated charge density distribution corresponding to the lace pattern, enhancing the adhesion of the raised patterned areas to the surface being adhered to, thereby improving overall bonding strength. Meanwhile, non-patterned areas maintain normal adhesion to ensure seamless peeling. Furthermore, the three-dimensional pattern is directly formed onto the substrate surface through embossing, with the pattern and substrate forming a continuous phase without interface bonding, fundamentally eliminating the risk of pattern detachment or interlayer peeling in traditional composite products. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0015] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0016] like Figure 1 The process flow shown includes: Step 1: Raw material preparation: Weigh the following raw materials by weight: 100 parts of SG-5 type PVC resin powder, 40 parts of TPR modified resin (thermoplastic elastomer based on SEBS), 140 parts of 1000-mesh calcium carbonate filler, 5 parts of calcium-zinc composite stabilizer, 0.3 parts of light-resistant additive (a mixture of hindered amine light stabilizer and ultraviolet absorber), 30 parts of plasticizer DOP, and 2 parts of antistatic agent.

[0017] The weighed raw materials were added to a high-speed mixer and mixed at 120°C for 12 minutes. During this process, the components were fully dispersed under high-speed shear: PVC resin powder and TPR modified resin were initially fused under the action of heat and mechanical force; calcium carbonate filler was evenly distributed in the resin system, playing a role in strengthening and reducing costs; calcium-zinc composite stabilizer effectively inhibited the thermal degradation of PVC in subsequent processing; lightfastness additives were dispersed in the system at the molecular level to provide long-term light aging protection for the product; plasticizer DOP penetrated between PVC molecular chains to weaken intermolecular forces and improve flexibility; and antistatic agent was evenly distributed on the surface of the system to assist in the effectiveness of subsequent electrostatic treatment. After mixing, the material was discharged for later use.

[0018] Step 2: Extrusion and plasticizing: The mixture obtained in step one is fed into a twin-screw extruder for melt plasticization. This twin-screw extruder has six heating zones arranged sequentially along the material's travel direction. The temperatures of each heating zone are set as follows: Zone 1 135℃, Zone 2 145℃, Zone 3 155℃, Zone 4 160℃, Zone 5 165℃, and Zone 6 170℃, with the die temperature controlled at 165℃. The residence time of the material in the extruder is controlled at 3 minutes. The purpose of this stepped heating temperature control scheme is: the lower initial temperature gradually preheats the material; the middle temperature promotes full melting and plasticization of the resin; and the final temperature ensures uniform melt temperature and viscosity before entering the die. The die temperature is slightly lower than the end of the extruder to prevent excessive melt flow and unstable output. The residence time of the material in the extruder should not be too short (otherwise plasticization will be insufficient) or too long (otherwise there is a risk of thermal degradation). A residence time of 3 minutes, under the above temperature conditions, ensures that the mixture is fully plasticized and has good melt homogeneity. The fully plasticized melt is extruded through a die and enters the next process.

[0019] Step 3: Calendering and simultaneous electrostatic treatment: The plasticized melt obtained in step two is fed into a four-roll calender for calendering. The temperatures of the four rolls of the four-roll calender are set sequentially as follows: roll one 175℃, roll two 170℃, roll three 165℃, and roll four 160℃. The gap between each roll decreases sequentially, allowing the melt to be gradually thinned and stretched as it passes through the gaps between the rolls, ultimately forming a continuous film substrate with a thickness of 0.32mm. The sequentially decreasing roll temperature design ensures that the film is gradually cooled and shaped during the thinning process, guaranteeing the forming quality of the film while avoiding stress concentration or surface defects caused by sudden temperature drops.

[0020] During the calendering process, an electrostatic application device positioned between the three-roll and four-roll mills applies high-voltage electrostatic charge to the still relatively hot surface of the film substrate, which has just emerged from the three-roll mill. This electrostatic application device includes multiple discharge electrodes uniformly distributed along the width of the film, with the distance between the electrodes and the film surface controlled at 10 mm. A 12 kV DC high-voltage electrostatic charge is applied. Under the high voltage, the discharge electrodes induce corona discharge in the air. The generated ions bombard and adhere to the film surface under the influence of the electric field, resulting in a uniform electrostatic charge on the film surface, with a surface electrostatic voltage reaching -8 kV. The electrostatic application device is positioned between the three-roll and four-roll mills, rather than after calendering is complete, because at this location the film is still at a relatively high temperature (approximately 160-165°C), resulting in strong polymer molecular chain mobility, low surface resistance, and superior charge injection efficiency and uniformity compared to room temperature conditions. In this step, the electrostatic adsorption functional layer forms synchronously with the calendering of the substrate, requiring no additional processing steps.

[0021] Step 4: Integrated embossing: The electrostatically charged film substrate obtained in step three is immediately fed into the embossing device under a heat preservation condition of 80°C for integrated embossing of the lace pattern. Here, "heat preservation condition" means that after the film comes out of the four-roll calender, it is transported to the embossing device through a heat preservation section (such as a heat preservation cover or heat preservation roller conveyor). During this process, the film temperature is maintained at around 80°C and has not yet cooled and solidified, thus remaining within the suitable plastic forming temperature range.

[0022] The embossing device includes an embossing roller and a back pressure roller that work together. The embossing roller is engraved with a lace pattern on its surface, with a pattern depth of 0.20 mm, and its temperature is controlled at 90℃; the temperature of the back pressure roller is controlled at 50℃; the pressing pressure is controlled at 5 MPa; and the traveling speed of the film substrate is controlled at 28 m / min.

[0023] When a statically charged thin film substrate enters the pressing area between the embossing roller and the back pressure roller, under a pressure of 5 MPa, the raised pattern on the surface of the embossing roller is pressed into the film surface, forming a three-dimensional lace-like indentation with a depth of 0.20 mm. Simultaneously, the patterned area undergoes significant plastic deformation due to the high compressive stress. Under this stress, the polymer molecular chains rearrange their orientation along the direction of force, resulting in a more compact and ordered arrangement of the molecular chains. This leads to an increase in both the material density and crystallinity of the patterned area. This change in microstructure significantly enhances the ability of the patterned area to bind and retain static charge. Meanwhile, the non-patterned area, which is not subjected to compressive stress or experiences less stress, retains its original microstructure and has a lower ability to retain static charge. It is this difference in microstructure between the patterned and non-patterned areas, caused by the synergistic effect of compressive stress and temperature field, that results in a differentiated charge density distribution on the film surface corresponding to the lace pattern—the charge density in the patterned area is higher than that in the non-patterned area. The advantage of this feature in practical use is that the patterned raised area is the part that is in the closest contact with the surface to which it is attached (such as glass). The enhanced adhesion in this area improves the overall adhesion of the product, while the non-patterned area maintains normal adhesion, ensuring that the product can be easily peeled off without leaving any residue when it needs to be removed.

[0024] In addition, the surface of the embossing roller is equipped with a scraper assembly. During the rotation of the embossing roller, the scraper continuously scrapes away any material that may remain in the non-patterned areas of the embossing roller, ensuring the clarity of the pattern transfer and the hollowing effect.

[0025] Step 5: Cooling and Shaping The embossed film obtained in step four is then subjected to segmented cooling and shaping via a first cooling roller and a second cooling roller. The temperature of the first cooling roller is 60°C, and the temperature of the second cooling roller is 30°C. The linear speed of the cooling rollers is synchronized with the travel speed of the embossing device (28 m / min). This two-stage, stepped cooling method, rather than rapid cooling, aims to fix the embossed pattern shape as the film gradually cools, while simultaneously eliminating internal stress generated during the embossing process and preventing pattern rebound, warping, or dimensional shrinkage caused by sudden temperature changes. After segmented cooling, the film temperature drops to near room temperature, and the pattern is firmly set.

[0026] Step Six: Slitting and Rewinding: The cooled and shaped film obtained in step five is then slit online according to product specifications. The slit width can be adjusted within the range of 0.3-1.5m according to customer needs. After slitting, the film surface is cleaned by a dust removal device to remove any dust or foreign matter that may have adhered during processing, and then it is wound into rolls by a winding device.

[0027] In addition, for products requiring long-term storage or long-distance transportation, a PET release film is applied to the electrostatic adsorption surface of the product using a lamination device before winding. This PET release film is 0.036 mm thick, and the lamination pressure is controlled at 1 MPa. The release film protects the electrostatic adsorption surface from dust, oil, and other contaminants during storage and transportation, preventing a decrease in electrostatic adsorption force and ensuring effective adsorption for end-users. Users can simply peel off the release film and apply the product directly to the window glass surface.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A one-piece molding process for a polymer electrostatic traceless self-adhesive film, characterized in that: Includes the following steps: S1. Raw material preparation: Weigh 100 parts of SG-5 type PVC resin powder, 30-50 parts of TPR modified resin, 120-160 parts of calcium carbonate filler, 4-6 parts of composite stabilizer, 0.2-0.5 parts of lightfastness additive, 25-35 parts of plasticizer, and 1-3 parts of antistatic agent according to the following weight proportions, and put them into a high-speed mixer and mix evenly to obtain a mixture. S2, Extrusion Plasticization: The mixture is fed into a twin-screw extruder for melt plasticization, and then extruded through a die to obtain a plasticized melt; S3. Calendering and synchronous electrostatic treatment: The plasticized melt is fed into a calender and calendered into a continuous film substrate; during the synchronous calendering process, a high voltage electrostatic charge is applied to the surface of the film substrate by an electrostatic application device set between the rollers of the calender, so that the surface of the film substrate carries a uniform electrostatic charge and forms an electrostatic adsorption functional layer. S4. Integrated embossing: The electrostatic film substrate obtained in step S3 is immediately fed into the embossing device under heat preservation to perform integrated embossing of the lace pattern. The embossing device includes an embossing roller and a back pressure roller. The three-dimensional lace pattern is formed by pressing the engraved pattern on the surface of the film substrate through the embossing roller. S5. Cooling and shaping: The embossed film obtained in step S4 is cooled and shaped sequentially. S6. Slitting and winding: The cooled and shaped film is slitted and wound online according to specifications.

2. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: The TPR modified resin in step S1 is a thermoplastic elastomer based on SEBSS hydrogenated styrene-butadiene-styrene block copolymer; the particle size of the calcium carbonate filler is 800-1500 mesh; the composite stabilizer is a calcium-zinc composite stabilizer; the lightfastness aid is a compound system of hindered amine light stabilizer and ultraviolet absorber; the plasticizer is DOP or DOTP; the high-speed mixing temperature is 110-130℃, and the mixing time is 8-15 minutes.

3. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: In step S2, the twin-screw extruder is equipped with six heating zones along the material travel direction. The temperatures of each heating zone are as follows: Zone 1 130-140℃, Zone 2 140-150℃, Zone 3 150-160℃, Zone 4 155-165℃, Zone 5 160-170℃, and Zone 6 165-175℃. The die temperature is controlled at 160-170℃. The residence time of the material in the extruder is controlled at 2-5 minutes.

4. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: The calender mentioned in step S3 is a four-roll calender, with the four roll temperatures as follows: first roll 170-180℃, second roll 165-175℃, third roll 160-170℃, and fourth roll 155-165℃, with the roll spacing decreasing sequentially. The plasticized melt is calendered into a continuous film substrate with a thickness of 0.25-0.40mm. The electrostatic application device includes multiple discharge electrodes evenly distributed along the width direction of the film. The distance between the electrodes and the film surface is controlled at 5-15mm. A DC high-voltage electrostatic voltage of 8-15kV is applied to make the static voltage on the surface of the film substrate reach -5kV to -10kV or +5kV to +10kV.

5. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: In step S4, the insulation temperature of the film substrate before entering the embossing device is 70-90℃; the temperature of the embossing roller is controlled at 80-100℃, the temperature of the back pressure roller is controlled at 40-60℃, the pressing pressure is controlled at 3-8MPa, and the traveling speed of the film substrate is controlled at 25-33m / min; the depth of the lace pattern engraved on the surface of the embossing roller is 0.15-0.30mm.

6. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: The cooling and shaping process in step S5 adopts a segmented cooling method: the embossed film passes through the first cooling roller and the second cooling roller in sequence. The temperature of the first cooling roller is 50-65℃, and the temperature of the second cooling roller is 20-35℃. The linear speed of the cooling roller is synchronized with the traveling speed of the embossing device.

7. The integral molding process of a polymer electrostatic traceless self-adhesive film according to claim 1, characterized in that: In step S4, the embossing roller achieves the hollowed-out effect of lace pattern through a scraper removal process. The embossing device also includes a scraper assembly set on the surface of the embossing roller to scrape off residual material in the non-patterned area of ​​the embossing roller, ensuring the clarity of the pattern transfer. Before slitting and winding in step S6, foreign matter on the film surface is also removed by a dust removal device.

8. A polymer electrostatic traceless self-adhesive film prepared by the integral molding process as described in any one of claims 1-7, characterized in that, The self-adhesive film is a single-layer integral structure, comprising: The substrate layer is composed of the PVC / TPR modified resin blend; The lace pattern layer is formed directly on at least one surface of the substrate layer through the integrated embossing process. The lace pattern layer and the substrate layer are the same continuous phase and are bonded without interface. The electrostatic adsorption functional layer is composed of electrostatic charges applied during the calendering process and is distributed on the surface and near-surface area of ​​the self-adhesive film. The patterned area of ​​the lace pattern layer has a higher ability to retain static charge than the non-patterned area due to the microstructural differences generated during the embossing process. This results in a higher charge density in the patterned area compared to the non-patterned area, forming a differentiated charge density distribution corresponding to the lace pattern.

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