Bottom-paper-free PVC cold laminating film and preparation method thereof

Abstract

The invention discloses a backing-paper-free PVC (polyvinyl chloride) cold laminating film and a preparation method thereof, and relates to the field of advertisement inkjet protective films. According to the preparation method of the backing-paper-free PVC cold laminating film, the thickness of a PVC film is set to be 50-100 microns; the PVC film comprises a substrate layer with the thickness of 30-68 microns from bottom to top; the thickness of the toughening layer is 6-10 microns; the protective layer is 6-10 microns; the thickness of the adhesive layer is 2-4 microns, and the thickness of the back layer is 2-4 microns, so that the prepared backing-paper-free PVC cold laminating film has high strength, wear resistance and good ultraviolet resistance, and the service life of a film material is prolonged; the adhesion performance and the processing stability of the film are improved through efficient surface treatment and coating processes; by controlling the multi-layer structure, the thickness and the components of the film, the product can meet the requirements of different applications and has better environmental friendliness; the production method of the cold laminating film has higher production efficiency, ensures the quality of a finished product, and is particularly suitable for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the field of advertising spray painting protective films, and particularly to a bottomless paper PVC cold laminating film and a preparation method thereof. Background Art

[0002] With the development of society, society has become increasingly diversified, and various advertisements and promotions can be seen everywhere in daily life. These advertisements, billboards and other carriers are usually presented by means such as painting and printing to attract people's attention. In order to ensure that advertisements and billboards can maintain bright colors and are not easily damaged in the environment of sun exposure, rain and frequent contact, the substrate is usually protected by laminating. At this time, the cold laminating film becomes a common protective material. The cold laminating film is made of transparent PVC material through back glue processing, and can be laminated on the surface of the photo printed image by hand or a cold laminating machine, so as to effectively prevent the picture from being scratched, polluted or affected by moisture, and play a role in protecting the picture.

[0003] The main feature of the bottomless paper PVC cold laminating film is that it does not use traditional base paper, but uses PET release film as the protective layer to improve the environmental protection and use convenience of the cold laminating film material. At present, some bottomless paper PVC cold laminating films may show problems such as decreased adhesion, peeling or blistering during long-term use, especially in environments with high temperature, high humidity or strong ultraviolet rays, and are prone to scratches or damages in high-frequency use occasions; In summary, how to improve the durability and scratch resistance of the bottomless paper PVC cold laminating film is an urgent problem to be solved and optimized in the preparation method of the bottomless paper PVC cold laminating film. Summary of the Invention

[0004] The present invention provides a bottomless paper PVC cold laminating film and a preparation method thereof, and solves the technical problem of how to improve the durability and scratch resistance of the bottomless paper PVC cold laminating film.

[0005] In order to solve the above technical problems, the present invention provides a bottomless paper PVC cold laminating film and a preparation method thereof, and the specific technical solutions are as follows: In a first aspect, a bottomless paper PVC cold laminating film, the thickness of the PVC film is 50-100 μm; the structure of the PVC film from bottom to top is respectively a base material layer of 30-68 μm; a toughening layer of 6-10 μm; a protective layer of 6-10 μm; an adhesion layer of 2-4 μm and a back layer of 2-4 μm.

[0006] As a further optimized solution of the present invention, the PVC film includes a glossy film, a matte film and a frosted film according to the surface texture.

[0007] As a further optimized solution of the present invention, 35-70 grams per square meter of bottom layer PVC resin and 20-40 grams per square meter of plasticizer need to be added to the base material layer.

[0008] As a further optimization scheme of the present invention, 15-30 g / m² of polyurethane resin needs to be added to the toughening layer: 2-4 g / m² of ultraviolet absorber and 10-15 g / m² of scratch-resistant transparent polyurethane need to be added to the protective layer.

[0009] As a further optimization scheme of the present invention, for the adhesive layer and the back layer, an antistatic coating with a thickness of 2-4 μm and a waterproof coating with a thickness of 1-5 μm need to be evenly applied to the back surface layer.

[0010] Second, a method for preparing a PVC cold laminating film without backing paper, the method for preparing a PVC cold laminating film without backing paper is applicable to the process steps of a PVC cold laminating film without backing paper, including the following steps: S1, melting the PVC material, and then extruding the melted PVC material to form a PVC film; S2, performing calendaring cooling on the PVC film; S3, shaping the cooled PVC film through a chill roll and performing a constant temperature tempering treatment; S4, performing longitudinal and transverse uniform stretching treatment on the PVC film after the constant temperature tempering treatment; S5, performing corona treatment on the lower surface of the PVC film; S6, coating an aqueous adhesive layer on the lower surface of the PVC film after corona treatment; S7, drying the coated PVC film; S8, winding and shaping to obtain a finished PVC cold laminating film without backing paper.

[0011] As a further optimization scheme of the present invention, when preparing the PVC film, the preparation environment temperature is 20-25 °C; the humidity is 40%-60%.

[0012] As a further optimization scheme of the present invention, in step S1, the die head temperature is controlled within the range of 210-230 °C, the extrusion temperature is controlled at 210-240 °C, and the extrusion pressure is controlled at 20-40 MPa; In step S2, the cooling rate is controlled at 2-4 m / s; In step S3, the temperature of the chill roll is controlled at 30-50 °C, and the tempering treatment is performed at a constant temperature within 160-182 °C; In step S4, the stretching ratio is 3-6 times; In step S5, after corona treatment, the surface energy of the PVC film is increased to 37-45 dyne / cm; In step S6, the water-based adhesive is water-based acrylic or water-based polyurethane glue; the coating thickness is 15 - 30 μm; In step S7, the drying treatment temperature is controlled at 50 - 70 °C to stably cure the adhesive layer.

[0013] As a further optimized solution of the present invention, in step S6, it further includes: The coated water-based adhesive layer is cured by ultraviolet rays, the curing time is 6 - 10 seconds, and the ultraviolet wavelength range is 250 - 350 nm.

[0014] As a further optimized solution of the present invention, the finished PVC film has no backing paper, its surface is smooth and bubble-free, and the surface tension is 38 - 43 dyne / cm.

[0015] The present invention has at least the following beneficial effects: By precisely controlling the thickness of the PVC film, the present invention ensures that the film layer has excellent mechanical properties, durability, and appropriate flexibility, and can meet the requirements of different application scenarios; multi-layer structure (substrate layer, toughening layer, protective layer, adhesion layer, back layer): The design of different layers (such as toughening layer, protective layer, adhesion layer, etc.) makes the film material have more uniform properties, ensuring the overall functionality and stability of the material: The toughening layer enhances the impact resistance of the film; the protective layer can prevent ultraviolet damage and extend the service life of the film material; the adhesion layer and the back layer improve the adhesion and electrostatic protection of the film, helping to reduce electrostatic accumulation during use and ensuring the bonding stability between the film material and the substrate.

[0016] The protective layer is added with ultraviolet absorbers and scratch-resistant polyurethane resins, which can effectively prevent the PVC film from aging and fading under ultraviolet irradiation, while improving the scratch resistance of the film and extending the service life.

[0017] By corona treatment, the surface energy of the PVC film is increased, thereby improving its adhesion to water-based adhesives (such as water-based acrylic or water-based polyurethane glue) and enhancing the adhesion stability of the film material. In addition, the use of water-based adhesives meets environmental protection requirements and avoids the use of organic solvents; the adhesive layer ensures good bonding between the film and other materials and will not cause insecure bonding due to being too thick or too thin.

[0018] Through the ultraviolet curing process, the water-based adhesive layer can be quickly cured in a short time, improving production efficiency and ensuring the quality of the film; appropriate temperature, humidity, and process parameters are used for the preparation of the PVC film (such as melting temperature control, cooling rate, draw ratio, etc.) to ensure the uniformity, flatness, and stability of the film during production. Especially in the control of environmental temperature and humidity, high-quality film materials with low deformation rates are ensured.

[0019] The surface tension is controlled within 38 - 43 dyne / cm. This surface tension range ensures a smooth film surface without bubbles, which is beneficial for subsequent processing and applications. A smooth surface can better adhere to other substrates and is less likely to have bubbles or unevenness.

[0020] Due to the excellent mechanical properties, UV resistance, surface smoothness, and good adhesion of this PVC cold laminating film, it can be widely used in multiple fields such as advertising signs, automobiles, construction, decoration, and protective films. Description of the Drawings

[0021] Figure 1 It is a structural diagram of a bottomless paper PVC cold laminating film provided by an embodiment of the present invention. Figure 2 It is a schematic process diagram of a bottomless paper PVC cold laminating film provided by an embodiment of the present invention. Detailed Embodiments

[0022] The following further describes the present application in detail with reference to the drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0023] A bottomless paper PVC cold laminating film and its preparation method provided by this embodiment are as follows: As Figure 1 shown, a bottomless paper PVC cold laminating film includes: The thickness of the PVC film is 50 - 100 μm; the structure of the PVC film from bottom to top is a substrate layer (100) of 30 - 68 μm; a toughening layer (200) of 6 - 10 μm; a protective layer (300) of 6 - 10 μm; an adhesive layer (400) of 2 - 4 μm; and a back layer (500) of 2 - 4 μm.

[0024] The PVC film includes a glossy film, a matte film, and a frosted film according to the surface texture.

[0025] Example 1 The surface of the glossy film is required to be smooth and highly transparent. Therefore, its manufacturing process needs to focus on the purity of raw materials, processing temperature, and mold surface treatment.

[0026] Raw material preparation: Use high-purity PVC resin (polyvinyl chloride resin); Add appropriate plasticizers (such as DOP, DINP) to improve the flexibility of the film; Add appropriate stabilizers, antioxidants, and UV absorbers to ensure the film has excellent weather resistance.

[0027] Preparation steps: Gradually add the above raw materials in proportion according to the specified weight and mix evenly; Heat in a twin-screw extruder to fully melt and form a uniform fluid; Cast film forming; The molten fluid passes through a casting die head and is extruded into a film shape; The surface of the casting die head is polished to a mirror finish to make the surface of the extruded film smooth and transparent; The extruded film is quickly cooled by a cooling roller to ensure no scratches on the surface; Prevent the film from wrinkling during the cooling process through a tension control device; The cooled film is wound into a roll and then cut into different sizes according to requirements.

[0028] Precautions: The surface of the die must reach a mirror-level finish, and any slight roughness will affect the transparency of the optical film; the cooling speed should be fast and uniform to avoid surface wrinkling or poor gloss caused by uneven cooling.

[0029] Example 2 The surface of the matte film has no gloss and presents a matte effect, which is usually achieved by controlling the light reflection characteristics of the film surface; Raw material preparation: Similar to the optical film, high-purity PVC resin, plasticizer, and stabilizer are used; Add an appropriate amount of matting agent (such as silica, barium sulfate, etc.) to reduce surface reflection.

[0030] Manufacturing steps: Mix the above raw materials in a twin-screw extruder and heat to form a uniform melt; Ensure that the matting agent is evenly dispersed in the resin to avoid particles or spots on the film surface; Use a specially treated matte die (the surface of the die has fine matte texture); The film melt is extruded and formed through the matte die, and the surface gloss is weakened by the die texture; The surface of the cooling roller is coated with a matting coating to keep the film matte during the cooling process; Control the cooling speed to ensure a uniform matte surface of the film.

[0031] When the matte effect on the film surface is not ideal, it can be further improved by coating a layer of matte coating.

[0032] Finally, after winding the matte film into a roll, cut it to the required size.

[0033] Precautions: The addition amount of the matting agent needs to be strictly controlled, generally 1%-5%. Excessive addition will lead to a decrease in the film strength; the texture details of the matte mold have a great influence on the surface gloss of the matte film, and repeated tests are required to determine the optimal mold parameters.

[0034] Example 3 The surface of the frosted film has uniform frosted texture and delicate touch, and is usually used for anti-glare, anti-fingerprint or decorative needs.

[0035] Raw material preparation: PVC resin and plasticizer are similar to those of the optical film and matte film; Add an appropriate amount of matting aids (such as polyacrylate microspheres or other special fillers) to form a matte effect on the film surface.

[0036] Manufacturing steps: Mix the above raw materials evenly in a twin-screw extruder to ensure that the matting aids are evenly dispersed in the PVC substrate; Use a matte mold. The surface of the mold is finely engraved with a matte texture, and the matting aid particles are controlled between 5-15 microns to ensure a delicate and uniform matte effect; The film is extruded through the matte mold, and regular or random matte textures are formed on the surface; The cooling roll is coated with a special texture coating to further enhance the matte effect on the film surface; Control the tension to avoid uneven matte patterns on the film surface during the cooling process; Use laser or sandblasting technology to perform secondary matting treatment on the film to enhance the touch and decoration; Wind up the film and cut it according to requirements.

[0037] Table 1: Comparison table of PVC film surface textures Example 4 Required raw materials: PVC film (polyvinyl chloride film), specifically required to be highly transparent, with weather resistance and anti-ultraviolet properties; Adhesive. In this example, the preferred type is acrylic pressure-sensitive adhesive, which is a high-transparency, high-adhesion, and anti-aging adhesive without residual glue; PET release film (release carrier replacing the base paper). In this example, the preferred type is PET film coated with silicone oil; Auxiliary materials: Anti-UV agent, used to improve weather resistance; stabilizer, used to prevent material aging and yellowing; Plasticizer, added in an appropriate amount to improve flexibility and avoid the material from being too hard; Base layer PVC resin, PVC (polyvinyl chloride) resin is used as the base layer material and is often suitable for anti-corrosion applications. It can be processed by extrusion, injection molding, calendering, etc., which is convenient for manufacturing products of different shapes and specifications. Compared with other high-performance resins, the production cost of PVC resin is lower, suitable for large-scale production, and has good anti-ultraviolet and weather resistance, capable of being used outdoors for a long time. The base layer PVC resin provides good structural strength and durability.

[0038] Polyurethane resin is a kind of polymer material with relatively wide applications and is often used in fields such as coatings, adhesives, elastomers, etc. Polyurethane resin has very excellent wear resistance and is often used to manufacture high-wear-resistant coatings and materials. Polyurethane resin has good elasticity and flexibility and is suitable for applications that require deformation and recovery. Polyurethane resin has good resistance to a variety of chemical substances (such as oils, fats, solvents, etc.) and is suitable for use in harsh environments. Polyurethane resin can bond with many different types of materials and has strong adhesion. After modification, polyurethane resin can improve its anti-ultraviolet and high-temperature resistance capabilities.

[0039] Ultraviolet absorber is a chemical substance that can absorb and block ultraviolet rays and is often used in materials such as coatings, plastics, and fibers. Ultraviolet absorber can effectively absorb ultraviolet rays, reduce the damage of ultraviolet rays to materials (such as plastics, coatings, etc.), and extend the service life. Ultraviolet rays can cause some coatings and plastics to fade, and ultraviolet absorber can effectively prevent this phenomenon. Ultraviolet absorber can reduce the aging effect of ultraviolet rays on materials and maintain the physical and chemical properties of materials. For transparent materials, ultraviolet absorber can effectively block the harm of ultraviolet rays to human skin, especially widely used in automotive glass and building glass.

[0040] Scratch-resistant transparent polyurethane is a kind of polyurethane resin with high transparency and excellent scratch resistance and is often used in coatings and films, which can significantly improve the surface wear and scratch resistance capabilities, extend the product service life, and maintain the highly transparent characteristic, making the coating or film not affect the appearance of the item, suitable for products that require high transparency (such as optical lenses, mobile phone screens, etc.), can effectively prevent the attachment of pollutants such as dust and oil stains on the surface, and keep the surface clean and shiny. The polyurethane coating can effectively resist the invasion of ultraviolet rays and prevent the surface from fading or aging.

[0041] An antistatic coating is a type of paint with antistatic properties that can prevent the generation or accumulation of static electricity. The antistatic coating can effectively conduct static electricity to the ground or other appropriate places, avoiding safety issues such as fires or explosions caused by static electricity accumulation. Static electricity is an important cause of damage to electronic devices. The antistatic coating can protect sensitive electronic products from static electricity interference or damage. In flammable and explosive environments, the antistatic coating can reduce the risk of accidents caused by static electricity discharge, reduce static electricity accumulation, and also reduce dust adhesion, improving the cleanliness of the working environment.

[0042] A waterproof coating is a type of paint that can prevent water penetration and is widely used in many fields such as construction, electronic products, and vehicles. The waterproof coating can effectively block water penetration, protect the basic structure from water damage, and extend the service life of items. Applying a waterproof coating on the metal surface can effectively prevent the reaction between water and metal, reducing rust and corrosion phenomena. The waterproof coating can prevent the influence of a humid environment on materials, especially protecting circuit boards from moisture in electronic products. The waterproof coating can be applied to a variety of substrates, including metals, plastics, concrete, etc., and is a common protection measure in fields such as construction, furniture, and appliances.

[0043] Precautions: Keep it clean during the preparation process to avoid dust contamination. It is most preferable to control the experimental environment temperature at 20 - 25°C and humidity at 40% - 60%; for the selection of raw materials, the PVC film and adhesive must ensure environmental protection and non-toxicity, meeting relevant standards (such as RoHS, REACH, etc.).

[0044] When preparing materials, ensure that all raw materials are dust-free and clean, especially the surfaces of the PVC film and PET release film, and any particles, dust, or oil stains should be avoided; As Figure 2 shown, a preparation method of a bottomless paper PVC cold laminating film is applicable to the process steps of a bottomless paper PVC cold laminating film, specifically including: S1, melt the PVC material, and then extrude the melted PVC material to form a PVC film; S2, perform calendaring cooling on the PVC film; S3, shape the cooled PVC film through a chill roll and perform a constant temperature tempering treatment; S4, perform longitudinal and transverse uniform stretching treatment on the PVC film after the constant temperature tempering treatment; S5, perform corona treatment on the lower surface of the PVC film; S6, coat an aqueous adhesive layer on the lower surface of the PVC film after corona treatment; S7, perform a drying treatment on the PVC film after coating; S8, wind and shape to obtain the finished product of the bottomless paper PVC cold laminating film.

[0045] Comparative Example 1 40 - 60 g / m² of base PVC resin and 10 - 20 g / m² of plasticizer need to be added to the base material layer; 3 - 4 g / m² of polyurethane resin needs to be added to the toughening layer: 2 - 4 g / m² of ultraviolet absorber and 8 - 10 g / m² of scratch-resistant transparent polyurethane need to be added to the protective layer; For the adhesion layer and the back layer, a 2 - 4 μm antistatic coating and a 0.5 - 1 μm waterproof coating need to be evenly applied on the coated back surface layer S1, Melt the PVC material through an extrusion molding process, control the die head temperature within the range of 200 - 210 °C, the extrusion temperature is controlled at 200 - 210 °C, and the extrusion pressure is controlled at 10 - 30 MPa to form a PVC film; S2, Conduct calendaring cooling on the PVC film, and control the cooling rate at 1 - 3 m / s; S3, Shape the film with a chill roll, control the temperature of the chill roll at 20 - 40 °C, and conduct a constant temperature tempering treatment at 155 - 165 °C; S4, Conduct longitudinal stretching treatment on the film, and the stretching ratio is 2 - 4 times; S5, Conduct corona treatment on the lower surface of the film to increase the surface energy of the film to 35 - 37 dyne / cm; S6, Coat a water-based adhesive layer on the lower surface of the treated film. The water-based adhesive is water-based acrylic or water-based polyurethane glue, and the coating thickness is 3 - 4 μm; The coated water-based adhesive layer is cured by ultraviolet light, the curing time is 2 - 4 seconds, and the ultraviolet wavelength range is 240 - 290 nm; S7, The coated film is dried at 35 - 70 °C to stably cure the adhesive layer; S8, Wind and shape to obtain a finished PVC cold laminating film without backing paper.

[0046] Comparative Example 2 55 - 80 g / m² of base PVC resin and 18 - 35 g / m² of plasticizer need to be added to the base material layer; 5 - 10 g / m² of polyurethane resin needs to be added to the toughening layer: 3 - 6 g / m² of ultraviolet absorber and 10 - 13 g / m² of scratch-resistant transparent polyurethane need to be added to the protective layer; For the adhesion layer and the back layer, a 4 - 6 μm antistatic coating and a 2 - 5 μm waterproof coating need to be evenly applied on the coated back surface layer S1. Melt the PVC material through an extrusion molding process, control the die head temperature within the range of 210 - 220 °C, the extrusion temperature within the range of 210 - 230 °C, and the extrusion pressure within the range of 30 - 40 MPa to form a PVC film; S2. Carry out casting cooling on the PVC film, and control the cooling rate at 2 - 5 m / s; S3. Shape the film with a chill roll, control the chill roll temperature at 35 - 50 °C, and perform a constant temperature tempering treatment at 166 - 170 °C; S4. Carry out longitudinal stretching treatment on the film, with a stretching ratio of 4 - 6 times; S5. Carry out corona treatment on the lower surface of the film to increase the surface energy of the film to 38 - 41 dyne / cm; S6. Coat an aqueous adhesive layer on the lower surface of the treated film. The aqueous adhesive is an aqueous acrylic or aqueous polyurethane glue, and the coating thickness is 5 - 10 μm; the coated aqueous adhesive layer is cured by ultraviolet light, the curing time is 3 - 5 seconds, and the ultraviolet wavelength range is 290 - 320 nm; S7. Dry the coated film at 60 - 70 °C to stably cure the adhesive layer; S8. Wind and shape to obtain a finished PVC cold laminating film without backing paper.

[0047] Comparative Example 3 60 - 90 g / m² of bottom PVC resin and 25 - 40 g / m² of plasticizer need to be added to the base material layer; 15 - 18 g / m² of polyurethane resin needs to be added to the toughening layer; 6 - 8 g / m² of ultraviolet absorber and 13 - 18 g / m² of scratch-resistant transparent polyurethane need to be added to the protective layer; For the adhesive layer and the back layer, a 6 - 8 μm antistatic coating and a 5 - 7 μm waterproof coating need to be evenly applied on the coated back surface layer S1. Melt the PVC material through an extrusion molding process, control the die head temperature within the range of 220 - 230 °C, the extrusion temperature within the range of 230 - 240 °C, and the extrusion pressure within the range of 40 - 45 MPa to form a PVC film; S2. Carry out casting cooling on the PVC film, and control the cooling rate at 5 - 8 m / s; S3. Shape the film with a chill roll, control the chill roll temperature at 50 - 55 °C, and perform a constant temperature tempering treatment at 170 - 175 °C; S4. Carry out longitudinal stretching treatment on the film, with a stretching ratio of 1 - 3 times; S5. Carry out corona treatment on the lower surface of the film to increase the surface energy of the film to 42 - 45 dyne / cm; S6. Coat an aqueous adhesive layer on the lower surface of the processed film. The aqueous adhesive is an aqueous acrylic or aqueous polyurethane glue, and the coating thickness is 10 - 15 μm. The coated aqueous adhesive layer is cured by ultraviolet light for 6 - 10 seconds, and the ultraviolet wavelength range is 330 - 360 nm. S7. The coated film is dried at 70 - 80 °C to stably cure the adhesive layer. S8. Wind and form to obtain a finished PVC cold laminating film without backing paper.

[0048] Experimental Example 1 Study the influence of the polyurethane resin content on the transparency and scratch resistance of the PVC cold laminating film.

[0049] Prepare mixtures of polyurethane resin and PVC resin with different ratios (such as mass ratios of 10:90, 20:80, 30:70, 40:60). Use a blending process to uniformly mix the two resins at a high temperature (180 °C), and extrude to form a film.

[0050] Spray a scratch-resistant transparent polyurethane coating on the film surface.

[0051] Testing: Measure the light transmittance (transparency) of the film.

[0052] Test its scratch resistance using a standard hardness pencil.

[0053] Observe its surface smoothness and coating adhesion.

[0054] Results: When the polyurethane content is low (10:90), the film has good transparency but poor scratch resistance.

[0055] As the polyurethane content increases to 30:70, the scratch resistance is significantly improved while maintaining good transparency.

[0056] When it exceeds 40:60, the transparency of the film decreases and the surface smoothness becomes poor.

[0057] Conclusion: The best ratio is 30:70, at which time the film has both good transparency and scratch resistance.

[0058] Experimental Example 2 Explore the influence of different ultraviolet absorber addition amounts on the anti-aging performance and service life of the cold laminating film.

[0059] Prepare PVC cold laminating film coatings with different ultraviolet absorber contents (0%, 0.5%, 1%, 2%).

[0060] Mix the ultraviolet absorber with the scratch-resistant transparent polyurethane and coat it on the surface of the PVC substrate.

[0061] Use an ultraviolet accelerated aging test machine to continuously irradiate the film with ultraviolet light (simulating natural light conditions).

[0062] Test the mechanical properties (such as breaking strength) of the coating through a tensile test.

[0063] Measure the color change (ΔE value) of the film to evaluate the degree of fading; Record the change in light transmittance.

[0064] Results: The film without the addition of ultraviolet absorber faded severely, and the coating was prone to aging and peeling.

[0065] After adding 0.5% ultraviolet absorber, the anti-aging performance improved slightly, but the effect was limited.

[0066] When 1% ultraviolet absorber was added, the anti-aging effect of the film was the best, and the mechanical properties of the coating remained stable.

[0067] When 2% was added, the excessive amount of ultraviolet absorber caused a decrease in the transparency of the film.

[0068] Conclusion: The optimal addition amount of the ultraviolet absorber is 1%.

[0069] Experimental Example 3 Evaluate the dust-proof effect and adhesion performance of the antistatic coating on the PVC cold laminating film without backing paper.

[0070] Prepare a coating solution containing an antistatic agent (the mass of the antistatic agent accounts for 0%, 1%, 2%, 3% of the total mass of the coating).

[0071] Uniformly coat the antistatic coating on the surface of the prepared PVC cold laminating film, and fix the coating through a hot air curing process; under room temperature conditions, expose the film surface to an environment containing dust (simulating indoor dust).

[0072] Measure the dust adhesion amount (unit: g / m²) with an electronic balance.

[0073] Test the antistatic performance of the coating through surface resistance, and evaluate the uniformity and adhesion of the coating.

[0074] Results: A large amount of dust accumulated on the surface of the film without the antistatic coating, and it was prone to electrostatic adsorption.

[0075] When the addition amount of the antistatic agent was 1%, the dust adhesion amount decreased by 50%, and the surface resistance decreased to 10 9 Ω.

[0076] When 2% was added, the dust-proof effect was further improved, but microcracks appeared on the coating surface.

[0077] When adding 3%, the adhesion of the coating decreases and the surface smoothness deteriorates.

[0078] Conclusion: The optimal addition amount of the antistatic agent is 1% - 2%.

[0079] Experimental Example 4 Study the effects of different waterproof coating processes on the waterproofness and moisture resistance of cold laminating films.

[0080] Prepare three waterproof coating processes: spraying (A), dip coating (B), and knife coating (C); Perform waterproof coating treatments on the surface of the PVC cold laminating film respectively and dry in an environment of 60 °C; Conduct a damp heat resistance test on the coated samples (high humidity 85%, temperature 40 °C, 48 hours).

[0081] Use a contact angle measuring instrument to evaluate the hydrophobicity of the surface (the larger the contact angle, the better the waterproofness).

[0082] Measure the peel strength of the coating to evaluate its moisture resistance.

[0083] Observe whether cracks or peeling occur on the surface of the coating.

[0084] Results: Spraying process (A): Good waterproofness (contact angle is 98°), but poor coating uniformity and general moisture resistance.

[0085] Dip coating process (B): Good coating uniformity (contact angle is 95°), good moisture resistance, but high cost.

[0086] Knife coating process (C): The contact angle reaches the highest (105°), significant waterproofness, but there are scratches on the surface.

[0087] Conclusion: The dip coating process has the best comprehensive performance and is suitable for large-scale production.

[0088] To sum up, to obtain the most preferred preparation material ratio table and preparation method parameter table, the details are as follows: Table 2: Preparation material ratio table Table 3: Preparation material ratio table In the gluing process, uniformly coat acrylic pressure-sensitive adhesive on the surface of the PET release film; The most preferred coating equipment is a knife coater or a roll coater to ensure coating uniformity; The coating amount is generally controlled at 20 - 50 g / m 2 , and adjust the thickness of the adhesive layer according to the use; Put the PET release film coated with adhesive into an oven for curing treatment. The drying temperature is set at 80 - 100 °C, and the drying time is preferably controlled at 5 - 10 minutes according to the glue characteristics, which can make the glue layer reach preliminary adhesion and avoid losing stickiness prematurely.

[0089] During the process of laminating with the PVC film, laminate the cured PET release film with the PVC film; The lamination method is completed by a composite laminating machine, and it is necessary to keep no bubbles and no wrinkles; The lamination pressure is preferably controlled at 0.3 - 0.5 MPa; The lamination speed is preferably maintained at 10 - 20 m / min; During the cooling and slitting process, cool the laminated cold laminating film to room temperature, Use cutting equipment to cut the whole roll of material into the required specifications (such as width 610 mm, 1220 mm, etc.).

[0090] During the quality inspection and packaging process, check whether the surface of the cold laminating film is flat and smooth, whether the glue layer is uniform and transparent, and whether there are bubbles or defects; qualified products are packaged with plastic film and stored in a dry and ventilated place; PVC film (polyvinyl chloride film), the specific requirements are high transparency, weather resistance and anti-ultraviolet characteristics, the thickness is 50 - 100 μm, and the grammage is 50 - 100 g / m²; Adhesive, the preferred type in this embodiment is acrylic pressure-sensitive adhesive, which is a high-transparency, high-adhesion, anti-aging adhesive without residual glue, and the preferred dosage is 20 - 50 g / m²; PET release film (release carrier replacing the base paper), the preferred type in this embodiment is a PET film coated with silicone oil, the thickness is 0.012 - 0.05 mm, and the grammage is 12 - 50 g / m².

[0091] The above embodiments only represent several implementation manners of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, which all belong to the protection scope of the present invention.

Claims

1. A PVC cold laminating film without backing paper, characterized in that, The thickness of the PVC film is 50 - 100 μm; the structure of the PVC film from bottom to top is respectively: a base material layer of 30 - 68 μm; a toughening layer of 6 - 10 μm; a protective layer of 6 - 10 μm; an adhesion layer of 2 - 4 μm; and a back layer of 2 - 4 μm.

2. The bottomless paper PVC cold laminating film according to claim 1, characterized in that, The PVC film includes a glossy film, a matte film, and a frosted film according to the surface texture.

3. The PVC cold laminating film without backing paper according to claim 2, characterized in that, 35 - 70 grams per square meter of bottom PVC resin and 20 - 40 grams per square meter of plasticizer need to be added to the base material layer.

4. The PVC cold laminating film without backing paper according to claim 3, characterized in that, 15 - 30 grams per square meter of polyurethane resin need to be added to the toughening layer: 2 - 4 grams per square meter of ultraviolet absorber and 10 - 15 grams per square meter of scratch-resistant transparent polyurethane need to be added to the protective layer.

5. A bottomless paper PVC cold laminating film according to claim 4, characterized in that, For the adhesion layer and the back layer, a 2 - 4 μm antistatic coating and a 1 - 5 μm waterproof coating need to be evenly applied on the coated back surface layer.

6. A preparation method of a PVC cold laminating film without backing paper, characterized in that, The preparation method of a PVC cold laminating film without base paper is applicable to the process steps of a PVC cold laminating film without base paper as described in any one of claims 1 - 5, and includes the following steps: S1, melting the PVC material, and then extruding and forming the melted PVC material to form a PVC film; S2, subjecting the PVC film to casting and cooling; S3, shaping the cooled PVC film through a chill roll and performing a constant-temperature tempering treatment; S4, performing longitudinal and transverse uniform stretching treatment on the PVC film after the constant-temperature tempering treatment; S5, performing corona treatment on the lower surface of the PVC film; S6, coating an aqueous adhesive layer on the lower surface of the PVC film after corona treatment; S7, drying the coated PVC film; S8, winding and forming to obtain a finished product of a PVC cold laminating film without base paper.

7. The preparation method of a PVC cold laminating film without base paper according to claim 6, characterized in that, When preparing the PVC film, the preparation environment temperature is 20 - 25 °C; the humidity is 40% - 60%.

8. The preparation method of a PVC cold laminating film without base paper according to claim 7, characterized in that In step S1, the die head temperature is controlled within the range of 210 - 230 °C, the extrusion temperature is controlled at 210 - 240 °C, and the extrusion pressure is controlled at 20 - 40 MPa; In step S2, the cooling rate is controlled at 2 - 4 m / s; In step S3, the temperature of the chill roll is controlled at 30 - 50 °C, and tempering treatment is performed at a constant temperature within 160 - 182 °C; In step S4, the stretching ratio is 3 - 6 times; In step S5, after corona treatment, the surface energy of the PVC film is increased to 37 - 45 dyne / cm; In step S6, the aqueous adhesive is aqueous acrylic or aqueous polyurethane glue; the coating thickness is 15 - 30 μm; In step S7, the drying treatment temperature is controlled at 50 - 70 °C to stably cure the adhesive layer.

9. The preparation method of a PVC cold laminating film without backing paper according to claim 8, characterized in that, In step S6, it further includes: The coated aqueous adhesive layer is cured by ultraviolet light, the curing time is 6 - 10 seconds, and the ultraviolet wavelength range is 250 - 350 nm.

10. The preparation method of a PVC cold laminating film without backing paper according to claim 9, characterized in that, The finished PVC film has no base paper, its surface is smooth and bubble-free, and the surface tension is 38 - 43 dyne / cm.

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