Water-based flame-retardant ink for pet film, method for manufacturing the same, and pet film

Abstract

The application provides a water-based flame-retardant ink for a PET film and a preparation method thereof and the PET film, and belongs to the technical field of paints. The water-based flame-retardant ink comprises a first component and a second component. The first component comprises 40-80wt% of a water-dispersed halogen-free modified polyester resin, 20-40wt% of a water-dispersed halogen-free flame-retardant additive, 5-10wt% of a quick-drying solvent, 0.3-0.5wt% of a defoaming agent, 0.3-0.5wt% of a wetting and leveling agent, 5-10wt% of a film-forming additive, 0.5-2wt% of an alkali-soluble anionic thickener and 5-10wt% of an anti-gloss additive. The second component comprises 40-70wt% of a water-dispersed crosslinking agent and 30-60wt% of an ester solvent. The mass ratio of the first component to the second component is 100:(3-10). The application can solve the compatibility problem of direct adhesion of the PET film and the flame retardation, and has no halogen emission and a long paint activation period.

Description

Technical Field

[0001] This invention relates to the technical field of coating compositions, and particularly to an aqueous flame-retardant ink for PET film, a method for manufacturing the same, and the PET film. Background Technology

[0002] Flame-retardant inks, as a functional material, are widely used in electronic devices, the automotive industry, building materials, and other fields. With increasing demands for environmental protection, low emissions, and fire safety, the performance requirements for flame-retardant inks are also rising.

[0003] The rapid development of electronic devices (such as mobile phones, computers, and smart home devices) and the automotive industry (such as new energy vehicles and intelligent vehicles) has led to more stringent requirements for flame-retardant materials. Environmental protection requirements are also becoming increasingly stringent. Furthermore, flame-retardant inks are commonly used in decorative materials and fire-retardant coatings to improve the fire resistance of building materials. They are also frequently used to print flame-retardant patterns to enhance the fire resistance of textiles.

[0004] PET (polyethylene terephthalate) film is a polymer material widely used in packaging, electronics, construction, and other fields. Due to its excellent physical properties (such as transparency, mechanical strength, and thermal stability) and chemical stability, PET film is used as a substrate in many applications. However, most PET films are currently coated with oil-based inks. Oil-based inks often contain harmful substances that do not meet national standards, especially excessive VOCs. Furthermore, oil-based inks typically contain large amounts of ketones and esters, posing flammable and explosive risks during production, transportation, storage, and use. Additionally, while traditional halogenated flame retardants are highly efficient and inexpensive, their combustion produces toxic fumes and hydrogen halide gases, which are harmful to the environment and human health.

[0005] In view of this, a novel water-based flame-retardant ink for PET film and its manufacturing method are proposed to solve all or part of the above problems. Summary of the Invention

[0006] To address at least one of the aforementioned problems and deficiencies in the prior art, embodiments of the present invention provide a water-based flame-retardant ink for PET film and its manufacturing method. The PET film utilizes a water-dispersible modified polyester resin with a specific particle size and a water-dispersible halogen-free phosphorus-based flame-retardant additive to synergistically solve the compatibility issue between direct adhesion to PET film and flame retardancy. Furthermore, it is a fully water-based formulation, safe and environmentally friendly, with extremely low VOC emissions. Simultaneously, mixing the first and second components during use effectively increases the coating's activation period by over 8 hours. Combined with the room-temperature, low-reaction-rate, long-activation-period crosslinking agent in the second component, a usage time of over 12 hours can be achieved. The technical solution is as follows:

[0007] According to one aspect of the present invention, an aqueous flame-retardant ink for PET film is provided. The aqueous flame-retardant ink comprises:

[0008] The first component, by mass fraction, comprises 40-80 wt% water-dispersible halogen-free modified polyester resin, 20-40 wt% water-dispersible halogen-free flame retardant, 5-10 wt% quick-drying solvent, 0.3-0.5 wt% defoamer, 0.3-0.5 wt% wetting and leveling agent, 5-10 wt% film-forming aid, 0.5-2 wt% alkali-soluble anionic thickener, and 5-10 wt% matting agent;

[0009] The second component comprises, by mass fraction, 40-70 wt% of a water-dispersible crosslinking agent and 30-60 wt% of an ester solvent;

[0010] The mass ratio of the first component to the second component is 100:(3-10).

[0011] In some embodiments, specifically, the water-dispersible halogen-free modified polyester resin has a glass transition temperature of 50-90°C and a particle size of 100-300 nm. The water-dispersible halogen-free flame retardant is a phosphorus-containing polymer dispersion with a phosphorus content of 6-8 wt% and a particle size of 200-500 nm.

[0012] In some embodiments, specifically, the hydroxyl value of the water-dispersible halogen-free modified polyester resin is ≤20 KOH mg / g, and the water-dispersible halogen-free modified polyester resin includes linearly modified polyester resins with a number average molecular weight of 5000-10000.

[0013] In some embodiments, preferably, the matting agent in the first component is silica matting powder with a particle size of 3-8 μm; the thickener is an acid-containing cross-linked acrylic emulsion copolymer; and the fast-drying solvent is ethanol or isopropanol.

[0014] In some embodiments, preferably, the water-dispersible crosslinking agent in the second component is an aziridine compound having an activation period of 8 hours or more.

[0015] In some embodiments, preferably, the water-based flame-retardant ink is applied to the surface of a PET film by microgravure coating and dried to form a water-based flame-retardant ink coating with a thickness of 13-15 μm. The water-based flame-retardant ink coating has an adhesion of ≥4B, a dyne value of ≥50, and can withstand alcohol wiping ≥200 times under a 500g load. The flame retardant rating is VT-0.

[0016] According to another aspect of the present invention, a method for preparing an aqueous flame-retardant ink for PET film is provided, the method being used to prepare the aqueous flame-retardant ink described in the above aspects. The method includes:

[0017] Step S101: Prepare the first component by mixing water-dispersible halogen-free modified polyester resin, water-dispersible halogen-free flame retardant additive, and fast-drying solvent after filtering through a 300-mesh filter and stirring at 200-600 rpm for 10-20 minutes.

[0018] Step S102: Add defoamer, wetting and leveling agent, film-forming aid, pH adjuster, thickener and matting agent in sequence and stir and filter simultaneously until the fineness is ≤5μm;

[0019] Step S103: Prepare the second component by mixing an aziridine crosslinking agent with an ester solvent;

[0020] Step S104: Before use, mix the first component and the second component at a mass fraction of 100:(3-10), add 5-10wt% deionized water to dilute and filter to form a water-based flame-retardant ink;

[0021] Step S105: When in use, a water-based flame-retardant ink coating is formed by micro-gravure coating followed by curing treatment.

[0022] In some embodiments, specifically in step S102, the defoamer and wetting leveling agent are slowly added to the mixed raw materials in step S101 at a rotation speed of 400-600 rpm.

[0023] In some embodiments, specifically in step S105, the ripening process specifically includes:

[0024] After the water-based flame-retardant ink is coated on the surface of the PET film, it is dried with hot air at 110-120℃ for 60-120 seconds.

[0025] After drying, the ink is cured at 50±2℃ for 24 hours to obtain a water-based flame-retardant ink coating with a dry film thickness of 13-15μm.

[0026] According to another aspect of the present invention, a PET film is provided, the surface of which is coated with a matte flame-retardant coating formed of an aqueous flame-retardant ink prepared according to the above aspects or an aqueous flame-retardant ink prepared according to the preparation methods described above.

[0027] The water-based flame-retardant ink for PET film and its manufacturing method provided by the embodiments of the present invention, and the PET film having at least one or a portion of the following advantages:

[0028] (1) The compatibility problem between direct-attached PET film and flame retardancy is solved by water-dispersible modified polyester resin with specific particle size and water-dispersible halogen-free phosphorus flame retardant additive. It is a fully water-based formula, which is safe and environmentally friendly with extremely low VOC emissions.

[0029] (2) By screening the water-dispersible modified polyester resin and mixing the first component with the second component during use, the activation period of the coating can be effectively increased to more than 8 hours. When combined with the crosslinking agent in the second component with low reaction rate and long activation period at room temperature, the service time can reach more than 12 hours.

[0030] (3) When coated onto PET film, no pretreatment or base coating is required. A stable coating can be formed on the surface of PET film directly by microgravure coating and drying and curing. The surface drying speed is fast and it does not become sticky.

[0031] (4) The coating adhesion of the water-based flame-retardant ink coating is ≥4B, the alcohol wiping resistance is ≥200 when the load is 500g, the dyne value is ≥50, the flame retardant level reaches VT-0, and it does not turn white when rubbed;

[0032] (5) Water-based flame-retardant inks do not contain heavy metals, halogens, or other environmentally harmful substances, making them safe and environmentally friendly;

[0033] (6) Water-dispersible modified polyester resin and water-dispersible halogen-free phosphorus flame retardant additives can be used to obtain water-based flame retardant inks by screening and proportioning commercially available materials. The process is simple and the production efficiency is high, which reduces the production cost.

[0034] (7) When coating on the surface of PET film, only micro-gravure coating process is required. Water-based flame-retardant ink material has high utilization rate, which can realize fast and continuous operation and improve production efficiency. Attached Figure Description

[0035] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of preferred embodiments taken in conjunction with the accompanying drawings, in which:

[0036] Figure 1 A flowchart illustrating a method for preparing water-based flame-retardant ink according to an embodiment of the present invention;

[0037] Figure 2 According to Figure 1 A physical image of an embodiment of the water-based flame-retardant ink obtained by the preparation method;

[0038] Figure 3 To be Figure 2 A photograph of the obtained water-based flame-retardant ink coated on a PET film. Detailed Implementation

[0039] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings. In this specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0040] This invention provides a water-based flame-retardant ink for PET film, its manufacturing method, and the PET film itself. The ink addresses the compatibility issue of direct adhesion to PET film and flame retardancy through the synergistic effect of a water-dispersible modified polyester resin with a specific particle size and a water-dispersible halogen-free phosphorus-based flame-retardant additive. It is a fully water-based formulation, safe and environmentally friendly, with extremely low VOC emissions. Furthermore, mixing the first and second components during use effectively increases the coating's activation period by over 8 hours. Combined with the room-temperature, low-reaction-rate, long-activation-period crosslinking agent in the second component, a usable time of over 12 hours can be achieved.

[0041] According to one aspect of the present invention, an aqueous flame-retardant ink for PET film is provided. The aqueous flame-retardant ink comprises:

[0042] The first component, by mass fraction, comprises 40-80 wt% water-dispersible halogen-free modified polyester resin, 20-40 wt% water-dispersible halogen-free flame retardant, 5-10 wt% quick-drying solvent, 0.3-0.5 wt% defoamer, 0.3-0.5 wt% wetting and leveling agent, 5-10 wt% film-forming aid, 0.5-2 wt% alkali-soluble anionic thickener, and 5-10 wt% matting agent;

[0043] The second component comprises, by mass fraction, 40-70 wt% of a water-dispersible crosslinking agent and 30-60 wt% of an ester solvent;

[0044] The mass ratio of the first component to the second component is 100:(3-10).

[0045] In use, the first and second components are first mixed with deionized water, and then coated onto the surface of a PET film material using a microgravure coating method. After drying, a water-based flame-retardant ink coating with stable adhesion, resistance to chemical corrosion, good scratch and abrasion resistance, and VT-0 flame retardant effect is formed on the surface of the PET film material. Simultaneously, this water-based flame-retardant ink coating has high surface tension, which facilitates subsequent printing, coating, and other processes.

[0046] In one example, specifically, the water-dispersible halogen-free modified polyester resin has a glass transition temperature of 50-90°C and a particle size of 100-300 nm. The water-dispersible halogen-free modified polyester resin should have a glass transition temperature of at least 40°C, preferably between 50-90°C. At this temperature, this type of modified polyester resin exhibits excellent quick-drying properties, workability, abrasion resistance, and hardness, and also demonstrates excellent adhesion to various types of plastic films.

[0047] In one example, specifically, the water-dispersible halogen-free modified polyester resin has a hydroxyl value ≤20 KOH mg / g, and the water-dispersible halogen-free modified polyester resin includes linearly modified polyester resins with a number average molecular weight of 5000-10000. This small amount of hydroxyl groups can chemically react with the curing agent (water-dispersible crosslinking agent) in the second component, improving the chemical resistance of the final water-based flame-retardant ink coating to alcohol and chemicals.

[0048] The water-dispersible halogen-free modified polyester resin exists in the emulsion with a main particle size distribution range of 100-300 nm. This particle size distribution can maintain the stability of the resin raw material and is not prone to precipitation or gelation problems. When made into water-based flame-retardant inks and coatings, they can form a smooth and balanced coating.

[0049] It should be noted that the water-dispersible halogen-free modified polyester resin is present in the coating composition (the mixture of the first components) at an amount of approximately 40-80 wt% based on weight. When its content is below 40%, the coating formed by this coating composition has low hardness and slow surface drying, leading to easy re-sticking during winding. Simultaneously, it reduces the overall crosslinking density of the coating, resulting in a decrease in properties such as alcohol resistance and adhesion. When its content is above 80%, the flame retardant effect of the coating formed by this coating composition deteriorates.

[0050] For example, commercially available modified polyester resins can be used for water-dispersible halogen-free modified polyester resins. Examples include waterborne polyester resins from Toyobo (e.g., MD-1200, MD-1245, MD-1500, and MD-2000); water-soluble saturated polyester resins from SK (e.g., EW 100G, EW 100D, EW 210, and EW 312); waterborne polyurethane dispersion resins from Mitsui (e.g., W-5030, WS-5000, WS-4022, and W-5661); and WJ 979, WE 2112, WF 9111, and WK 3108 from Hanhai. The above selection of specific materials is merely illustrative and should not be construed as a limitation of the invention. Subsequent selections of specific components are similar and will not be elaborated further.

[0051] In the process of preparing the water-based flame-retardant ink of this invention, suitable modified polyester resin raw materials need to be screened as water-dispersible halogen-free modified polyester resins through experiments and parameter determination. The screening criteria mainly include evaluating the adhesion of the modified polyester resin raw materials to PET.

[0052] In one example, PET adhesion was tested by mixing various types of modified polyester resin raw materials in fixed component proportions (e.g., 80%) with DMEA (amine pH adjuster), BYK024 (defoamer), BYK348 (wetting and leveling agent), E-1011 (matting agent), and ethylene glycol butane (film-forming aid) in deionized water and adding a fixed proportion of isocyanate curing agent (e.g., CSNB-W20523).

[0053] Experimental tests show that PA-type acrylic resins have no adhesion to PET, and PUD-type polyurethane resins, except for some models like RE-2108, have no adhesion and also exhibit re-tack issues. Most commercially available PE-type polyester resins show good adhesion to PET (reaching the 4B level).

[0054] Therefore, the first step is to screen waterborne PE resins or water-dispersible PE resins from commercially available modified polyester resin raw materials. Then, a second performance evaluation (mainly assessing flame retardancy and adhesion) is required using the screened waterborne PE resins or water-dispersible PE resins mixed with flame retardants to obtain a water-dispersible halogen-free modified polyester resin suitable for preparing waterborne halogen-free modified polyester resins that meet the parameter requirements for preparing waterborne halogen-free flame-retardant inks of this invention.

[0055] After obtaining the water-dispersible halogen-free modified polyester resin (which may be a commercially available modified polyester resin raw material, or two or more commercially available modified polyester resins mixed in a certain proportion), further screening is conducted for water-dispersible halogen-free flame retardant additives suitable for the water-based flame retardant ink of the present invention.

[0056] In one example, commercially available water-based PE resins mixed with APP flame retardants achieved the required flame retardant effect but suffered from decreased adhesion. Water-based PE resins of types MD-1200, EW 100G, and W-5030, when mixed with APP flame retardants, achieved the required adhesion but exhibited a sticky-on-the-tack problem. Water-based PE resins of type WK3108 could simultaneously achieve good adhesion and prevent sticky-on-the-tack, but after being left at room temperature for one day, it reacted with the flame retardant and gelled. Therefore, further screening of water-dispersible halogen-free flame retardant additives is needed.

[0057] In one example, specifically, the water-dispersible halogen-free flame retardant is a phosphorus-containing polymer dispersion with a phosphorus content of 6-8 wt% and a particle size of 200-500 nm.

[0058] The flame-retardant mechanism of this water-dispersible halogen-free flame retardant is as follows: Phosphoric anhydride is formed, acting as a dehydrating agent and promoting char formation. Char formation reduces heat transfer from the flame to the condensed phase. Phosphoric acid is endothermic, preventing CO oxidation to CO2 and reducing the heating process. A thin glassy or liquid protective layer is formed on the condensed phase, thus reducing oxygen diffusion and heat and mass transfer between the gas and solid phases, inhibiting char oxidation, and reducing the thermal decomposition of phosphorus-containing flame retardants to produce poly(methoxyphosphoric acid). Poly(methoxyphosphoric acid) is a stable, non-volatile compound with strong dehydrating properties. The released water vapor absorbs a large amount of heat, causing the flame retardant on the polymer surface to decompose and release volatile phosphides. Mass spectrometry analysis shows a significantly reduced hydrogen atom concentration, indicating that PO ions capture H ions to form HPO.

[0059] This water-dispersible, halogen-free flame retardant additive is halogen-free and can be directly dispersed in aqueous systems without grinding or other processes. It typically has a number average molecular weight of approximately 8000-10000 and is emulsifier-free. The polymeric dispersant molecular chain contains hydrophilic groups, which can react with the crosslinking agent in the second component. This effectively ensures that the resulting coating exhibits excellent water and chemical resistance.

[0060] The phosphorus-containing polymer dispersion in this water-dispersible halogen-free flame retardant exists in a particle size range of 200-500 nm, forming an aqueous dispersion. This particle size increases the stability and additivity of the water-dispersible halogen-free flame retardant and imparts an excellent appearance to the coating. Its phosphorus content is approximately 6-8%, fully meeting the V0 flame retardant requirements.

[0061] Typically, water-dispersible halogen-free flame retardant additives are present in the coating composition at an amount of approximately 15-35 wt% based on weight. When the content is below 15%, the flame retardant effect of the coating formed by the coating composition deteriorates. When the content is above 35%, the adhesion of the coating formed by the coating composition to the PET film deteriorates, the coating softens, and re-sticking problems easily occur during winding.

[0062] For example, commercially available water-dispersible halogen-free flame retardants can be used as water-dispersible halogen-free flame retardants. Examples include DTFR-6007, a water-soluble phosphate flame retardant from Dongtuo; AP420, a water-dispersible halogen-free flame retardant from Clariant; DF P1W from Shuangjie; BR-106 from Youju; HY-FR083 from Huilai; and Hera-215NC from BZ.

[0063] In the process of preparing the water-based flame-retardant ink of this invention, it is necessary to screen suitable water-dispersible halogen-free flame-retardant additives through experiments and parameter determination. The screening criteria mainly include evaluating the flame retardancy and dispersibility of the water-based system after mixing water-based PE resin or water-dispersible PE resin (water-dispersible halogen-free modified polyester resin) with water-dispersible halogen-free flame-retardant additives.

[0064] In one example, the flame retardancy, water-based system dispersibility, and anti-tack properties were tested by mixing waterborne PE resins or water-dispersible PE resins selected through preliminary adhesion tests at a fixed component ratio (e.g., 60%) with various water-dispersible halogen-free flame retardants and DMEA (amine pH modifier), BYK024 (defoamer), BYK348 (wetting and leveling agent), E-1011 (matting agent), ethylene glycol butyl (film-forming aid), and AS1130 (thickener) in deionized water and adding a fixed proportion of isocyanate curing agent (e.g., CSNB-W20523).

[0065] Experimental tests show that solid flame retardants (such as 5900 and Mg(OH)2) have better flame retardant effects when mixed with water-based or water-dispersible PE resins, but their poor dispersibility in water-based systems results in particulate coatings and affects adhesion. Among liquid water-dispersible phosphorus-containing flame retardants, only HY-FR083 meets the flame retardant requirements, but it can cause sticking issues.

[0066] Furthermore, after screening out the better water-dispersible halogen-free flame retardant (which can be a commercially available water-dispersible halogen-free flame retardant or a mixture of two or more commercially available water-dispersible halogen-free flame retardants in a certain proportion), the type of other solvents in the first component or the proportion of different solvents is adjusted to improve the stickiness problem.

[0067] Furthermore, the water-dispersible halogen-free modified polyester resins selected through experimental testing generally have a glass transition temperature of 50-90℃ and a particle size of 100-300nm. In addition, the hydroxyl value of the water-dispersible halogen-free modified polyester resins is ≤20 KOH mg / g, including linearly modified polyester resins with a number average molecular weight of 5000-10000.

[0068] Water-dispersible halogen-free flame retardant additives selected through experimental testing generally have a phosphorus content of 6-8 wt% and a particle size of 200-500 nm in the phosphorus-containing polymer dispersion. In one example, preferably, the matting agent in the first component is silica matting powder with a particle size of 3-8 μm; the thickener is an acid-containing cross-linked acrylic emulsion copolymer; and the fast-drying solvent is ethanol or isopropanol.

[0069] Preferably, an alkali-soluble anionic thickener is used, which is an acid-containing crosslinked acrylic emulsion copolymer. When diluted with water and neutralized with alkali, the emulsion particles in this type of thickener swell rapidly. Polyacrylic acid thickeners effectively improve low-shear-rate viscosity, resulting in a coating with high-shear-dilution characteristics, thereby ensuring excellent workability and preventing sagging.

[0070] For example, thickeners can be commercially available materials. Examples include Rheolate 150 and Rheolate 175 from Element; DS 6256 and AS1130 from Basf; and ACRYSOL™ ASE-60, TT-935, UCARPOLYPHONE T-900, and T-901 from Dow. AS1130 from Basf is preferred.

[0071] In one example, preferably, the water-dispersible crosslinking agent in the second component is an aziridine compound having an activation period of 8 hours or more.

[0072] Typically, the second component, which forms the curing agent, is added to the first component at a weight ratio of 3-10%. The two components are thoroughly mixed before coating application. When the second component curing agent content is less than 3%, the coating's resistance to chemicals such as alcohol deteriorates. When this content exceeds 10%, the coating becomes too hard, resulting in poor adhesion to PET film and a shorter activation period.

[0073] For example, water-dispersible crosslinking agents (aziridine compounds) can be commercially available polyurethane resin materials. Examples include CX-100 from Covestro; P350 from Haoyi; DK100 from Dike Biotechnology; HS-100A from Hongsui; and SaC-100 from Youen, etc.

[0074] In one example, preferably, the water-based flame-retardant ink is applied to the surface of a PET film by microgravure coating and dried to form a water-based flame-retardant ink coating with a thickness of 13-15μm. The water-based flame-retardant ink coating has an adhesion of ≥4B, a dyne value of ≥50, and can withstand alcohol wiping ≥200 times under a 500g load. The flame retardant rating is VT-0.

[0075] According to another aspect of the present invention, a method for preparing an aqueous flame-retardant ink for PET film is provided, the method being used to prepare the aqueous flame-retardant ink described in the above aspects.

[0076] See Figure 1 The specific process steps of this preparation method are shown. The preparation method includes:

[0077] Step S101: Prepare the first component by mixing water-dispersible halogen-free modified polyester resin, water-dispersible halogen-free flame retardant additive, and fast-drying solvent after filtering through a 300-mesh filter and stirring at 200-600 rpm for 10-20 minutes.

[0078] Step S102: Add defoamer, wetting and leveling agent, film-forming aid, pH adjuster, thickener and matting agent in sequence and stir and filter simultaneously until the fineness is ≤5μm;

[0079] Step S103: Prepare the second component by mixing an aziridine crosslinking agent with an ester solvent;

[0080] Step S104: Before use, mix the first component and the second component at a mass fraction of 100:(3-10), add 5-10wt% deionized water to dilute and filter to form a water-based flame-retardant ink;

[0081] Step S105: When in use, a water-based flame-retardant ink coating is formed by micro-gravure coating followed by curing treatment.

[0082] In one example, specifically in step S102, the defoamer and wetting leveling agent are slowly added to the mixed raw materials in step S101 at a rotation speed of 400-600 rpm.

[0083] In one example, specifically in step S105, the ripening process includes:

[0084] 1. After coating the surface of the PET film with water-based flame-retardant ink, dry it with hot air at 110-120℃ for 60-120 seconds;

[0085] 2. After drying, the ink is cured at 50±2℃ for 24 hours to obtain a water-based flame-retardant ink coating with a dry film thickness of 13-15μm.

[0086] According to another aspect of the present invention, a PET film is provided, the surface of which is coated with a matte flame-retardant coating formed of an aqueous flame-retardant ink prepared according to the above aspects or an aqueous flame-retardant ink prepared according to the preparation methods described above.

[0087] Example 1

[0088] The following example, through a specific formulation and preparation method, further illustrates the water-based flame-retardant ink and its preparation method provided by the present invention.

[0089] The specific proportions of the first component, by mass percentage, include: water-dispersible modified polyester resin: 60%, water-dispersible halogen-free flame retardant: 20%, alcohol (fast-drying solvent): 5%, BYK 024 (defoamer): 0.3%, BYK 348 (wetting and leveling agent): 0.3%, ethylene glycol butyl ether (film-forming aid): 5%, DMEA (amine pH adjuster): 0.3%, AS1130 (thickener): 1.5%, E-1011 (matting agent): 5%, and deionized water: 2.6%.

[0090] The specific proportions of the second component, by mass percentage, include: HS-100A (water-dispersible crosslinking agent): 50%, PMA (ester solvent): 50%.

[0091] After obtaining the first and second components mentioned above, the process flow for preparing water-based flame-retardant ink is as follows:

[0092] 1. Weigh the water-dispersible modified polyester resin, water-dispersible halogen-free flame retardant and alcohol according to the weight percentage of the above components, filter them through a 300-mesh filter cloth and add them to a stainless steel mixing tank, and stir with a disperser at a speed of 200-400 rpm for 10-20 minutes.

[0093] 2. Weigh BYK 024 and BYK 348 from the first component according to their respective weight percentages. Increase the speed of the disperser to 400-600 rpm and slowly add them to the stainless steel mixing tank while stirring and dispersing. Stir at 400-600 rpm for 10-20 minutes and scrape the fineness plate to ensure there are no shrinkage cavities, particles, or other abnormalities.

[0094] 3. Weigh the ethylene glycol butyl ether in the first component according to the weight percentage, mix it with deionized water at a weight ratio of 1:1, reduce the speed of the disperser to 200-400 rpm, and add it to the stainless steel mixing tank while dispersing and stirring.

[0095] 4. Weigh the DMEA in the first component according to the weight percentage, mix it with deionized water at a weight ratio of 1:1, and then cool it to room temperature. After cooling, filter it into a stainless steel mixing tank while dispersing and stirring using a 300-mesh filter cloth.

[0096] 5. Weigh AS1130 in the first component according to the weight percentage, mix it with deionized water at a weight ratio of 1:1, and filter it into a stainless steel mixing tank while dispersing and stirring through a 300-mesh filter cloth.

[0097] 6. Weigh the E-1011 in the first component according to the weight percentage, increase the speed of the disperser to 400-600 rpm, and slowly add it to the stainless steel mixing tank while dispersing.

[0098] 7. After continuing to disperse and stir for 10-20 minutes, use a fineness tester to check the fineness, and measure the pH value, viscosity, and fixed component content to see if they meet the standards.

[0099] When a coating needs to be applied to a PET film, the first component and the second component are mixed at a mass fraction of 100:(3-10) before use, and 5-10wt% deionized water is added for dilution and filtration to form a water-based flame-retardant ink. When using, the ink is coated by microgravure and then cured to form a water-based flame-retardant ink coating.

[0100] Specifically, in this embodiment, preferably, the first component, the second component, and deionized water are stirred and mixed evenly at a mass fraction of 100:5:5-10, and then filtered using a 300-mesh nylon mesh. Microgravure coating is then performed without a primer. Rollers coat the water-based flame-retardant ink onto the PET film substrate, with a coating thickness of 13-15 μm.

[0101] After coating, the material is baked in a hot air oven at 110-120℃ for 60-120 seconds until it is surface dry and does not become sticky again. After surface drying, the material is rolled up and placed in an oven at 50±2℃ for 24 hours to cure. After curing, relevant performance tests can be performed. The final product is a transparent PET film with a substrate of 0.025 mm.

[0102] See Table 1 for the test results of the water-based flame-retardant ink obtained in Example 1. See Table 2 for the performance test results of the water-based flame-retardant ink obtained in Example 1.

[0103] Table 1. Test results of the water-based flame-retardant ink in Example 1

[0104]

[0105] Table 2 Performance test results of water-based flame-retardant ink in Example 1

[0106]

[0107] As can be seen from the test results in Tables 1 and 2 above, the water-based flame-retardant ink of the present invention is superior to commercially available products in all core performance aspects.

[0108] The water-based flame-retardant ink for PET film and its manufacturing method provided by the embodiments of the present invention, and the PET film having at least one or a portion of the following advantages:

[0109] (1) The compatibility problem between direct-attached PET film and flame retardancy is solved by water-dispersible modified polyester resin with specific particle size and water-dispersible halogen-free phosphorus flame retardant additive. It is a fully water-based formula, which is safe and environmentally friendly with extremely low VOC emissions.

[0110] (2) By screening the water-dispersible modified polyester resin and mixing the first component with the second component during use, the activation period of the coating can be effectively increased to more than 8 hours. When combined with the crosslinking agent in the second component with low reaction rate and long activation period at room temperature, the service time can reach more than 12 hours.

[0111] (3) When coated onto PET film, no pretreatment or base coating is required. A stable coating can be formed on the surface of PET film directly by microgravure coating and drying and curing. The surface drying speed is fast and it does not become sticky.

[0112] (4) The coating adhesion of the water-based flame-retardant ink coating is ≥4B, the alcohol wiping resistance is ≥200 when the load is 500g, the dyne value is ≥50, the flame retardant level reaches VT-0, and it does not turn white when rubbed;

[0113] (5) Water-based flame-retardant inks do not contain heavy metals, halogens, or other environmentally harmful substances, making them safe and environmentally friendly;

[0114] (6) Water-dispersible modified polyester resin and water-dispersible halogen-free phosphorus flame retardant additives can be used to obtain water-based flame retardant inks by screening and proportioning commercially available materials. The process is simple and the production efficiency is high, which reduces the production cost.

[0115] (7) When coating on the surface of PET film, only micro-gravure coating process is required. Water-based flame-retardant ink material has high utilization rate, which can realize fast and continuous operation and improve production efficiency.

[0116] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. An aqueous flame retardant ink for PET film, characterized by, The water-based flame-retardant ink comprises: A first component, which comprises, by mass fraction, 40-80wt% of a water-dispersible halogen-free modified polyester resin, 20-40wt% of a water-dispersible halogen-free flame-retardant additive, 5-10wt% of a quick-drying solvent, 0.3-0.5wt% of an antifoaming agent, 0.3-0.5wt% of a wetting and leveling agent, 5-10wt% of a film-forming aid, 0.5-2wt% of an alkali-soluble anionic thickening agent, and 5-10wt% of a matting aid, with the remainder being deionized water; wherein The water-dispersible halogen-free modified polyester resin has a glass transition temperature of 50-90℃ and a particle size of 100-300nm; The water-dispersible halogen-free flame-retardant additive is a phosphorus-containing polymer dispersion having a phosphorus content of 6-8wt% and a particle size of 200-500nm; A second component, which comprises, by mass fraction, 40-70wt% of a water-dispersible crosslinking agent and 30-60wt% of an ester solvent; wherein The water-dispersible crosslinking agent is an aziridine compound having an activation period of greater than or equal to 8 hours; The mass ratio of the first component to the second component is 100:(3-10).

2. The water-based flame-retardant ink according to claim 1, wherein The water-dispersible halogen-free modified polyester resin has a hydroxyl value of ≤20 KOH mg / g and comprises a linear chain modified polyester resin having a number average molecular weight of 5000-10000.

3. The water-based flame-retardant ink according to claim 1 or 2, wherein The matting aid in the first component is a silica matting powder having a particle size of 3-8μm; The thickening agent in the first component is an acid-containing crosslinked acrylic acid emulsion copolymer; The quick-drying solvent in the first component is ethanol or isopropyl alcohol.

4. The water-based flame-retardant ink according to claim 3, wherein The water-based flame-retardant ink is applied on the surface of a PET film by micro-recess coating and forms a water-based flame-retardant ink coating layer having a thickness of 13-15μm after drying, the adhesion of the water-based flame-retardant ink coating layer is ≥4B, the dyne value is ≥50, the resistance to alcohol wiping is ≥200 times under a load of 500g, and the flame-retardant grade is VT-0.

5. A method for the preparation of a water-based flame retardant ink for PET films, said method for the preparation of a water-based flame retardant ink according to any one of claims 1-4, characterized in that, The preparation method comprises: Step S101: preparing a first component, mixing the water-dispersible halogen-free modified polyester resin, the water-dispersible halogen-free flame-retardant additive, and the quick-drying solvent after filtering through a 300-mesh filter, and stirring at a speed of 200-600rpm for 10-20 minutes; Step S102: sequentially adding the antifoaming agent, the wetting and leveling agent, the film-forming aid, the pH adjuster, the thickening agent, and the matting aid while stirring, and filtering to a fineness of ≤5μm; Step S103: preparing a second component, mixing the aziridine crosslinking agent and the ester solvent; Step S104: mixing the first component and the second component in a mass ratio of 100:(3-10) before use, adding 5-10wt% of deionized water for dilution, and filtering to form the water-based flame-retardant ink. Step S105: After micro-concave coating, the water-based flame-retardant ink coating is formed by maturation treatment.

6. The preparation method according to claim 5, characterized in that, In step S102, the defoaming agent and the wetting leveling agent are slowly added into the mixed raw materials of step S101 at a rotation speed of 400-600 rpm.

7. The preparation method according to claim 6, characterized in that, In step S105, the maturation treatment specifically includes: After the water-based flame-retardant ink is coated on the surface of the PET film, hot air drying is performed at a temperature of 110-120℃ for 60-120 seconds; After drying, maturation is performed at a temperature of 50±2℃ for 24 hours to obtain a water-based flame-retardant ink coating with a dry film thickness of 13-15μm.

8. A PET film, characterized by, The surface of the PET film is coated with a matte flame-retardant coating formed by the water-based flame-retardant ink according to any one of claims 1-4 or prepared by the preparation method according to any one of claims 5-7.

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