Water-based flame-retardant ink for PET (polyethylene terephthalate) film, manufacturing method of water-based flame-retardant ink

Abstract

The invention provides water-based flame-retardant ink for a PET (Polyethylene Terephthalate) film, a preparation method of the water-based flame-retardant ink and the PET film, and belongs to the technical field of coatings. Comprising a first component and a second component, wherein the first component is prepared from the following components in percentage by mass: 40 to 80 weight percent of water-dispersed halogen-free modified polyester resin, 20 to 40 weight percent of water-dispersed halogen-free flame-retardant aid, 5 to 10 weight percent of quick-drying solvent, 0.3 to 0.5 weight percent of defoaming agent, 0.3 to 0.5 weight percent of wetting flatting agent, 5 to 10 weight percent of coalescing agent, 0.5 to 2 weight percent of alkali-soluble anionic thickener and 5 to 10 weight percent of matting aid; the second component comprises the following components in percentage by mass: 40-70wt% of a water dispersible cross-linking agent and 30-60wt% of an ester solvent; the mass ratio of the first component to the second component is 100: (3-10). According to the invention, the compatibility problem of direct adhesion of a PET film and flame retardance can be synergistically solved, no halogen is discharged, and the activation period of the coating is long.

Description

Technical Field

[0001] The present invention relates to the technical field of coating compositions, and in particular to a water-based flame-retardant ink for a PET film, a preparation method thereof, and the PET film. Background Art

[0002] As a functional material, flame retardant ink is widely used in electronic equipment, automotive industry, building materials and other fields. With the increasing requirements for environmental protection, low emissions, fire safety, etc., the performance requirements for flame retardant ink are also further improved.

[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 smart cars) has led to stricter 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 enhance the fire resistance of building materials. They are also commonly used to print flame-retardant patterns to improve 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 ink coatings often contain hazardous substances that do not meet national standards, particularly excessive levels of VOCs. Furthermore, oil-based inks often contain large amounts of volatile solvents such as ketones and esters, creating flammability and explosion risks during production, transportation, storage, and use. Furthermore, while traditional halogen flame retardants are highly effective and inexpensive, they produce toxic fumes and hydrogen halide gases when burned, which are harmful to the environment and health.

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

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

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

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

[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, 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 additive is a phosphorus-containing polymer dispersion having 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 a linear straight-chain modified polyester resin with a number average molecular weight of 5,000-10,000.

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

[0014] In some embodiments, preferably, the water-dispersible crosslinking agent in the second component is an aziridine compound, and the aziridine compound has an activation period of greater than or equal to 8 hours.

[0015] In some embodiments, preferably, the water-based flame retardant ink is applied to the surface of the PET film by micro-dimpled 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, an alcohol wipe resistance of ≥200 times under a load of 500 g, and a flame retardant grade of VT-0.

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

[0017] Step S101: preparing a first component, filtering a water-dispersible halogen-free modified polyester resin, a water-dispersible halogen-free flame retardant additive, and a quick-drying solvent through a 300-mesh filter, mixing the mixture, and stirring the mixture at a speed of 200-600 rpm for 10-20 minutes;

[0018] Step S102: adding defoaming agent, wetting and leveling agent, film-forming agent, pH regulator, thickener and matting agent in sequence and stirring and filtering simultaneously until the fineness is ≤5μm;

[0019] Step S103: preparing a second component by mixing an aziridine cross-linking agent with an ester solvent;

[0020] Step S104: Before use, the first component and the second component are mixed at a mass fraction of 100:(3-10), and 5-10 wt% deionized water is added 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-dimpled coating followed by aging treatment.

[0022] In some embodiments, specifically, in step S102, the defoaming agent and the wetting and 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 aging process includes:

[0024] After coating the water-based flame retardant ink on the surface of the PET film, it is dried with hot air at a temperature of 110-120°C for 60-120 seconds;

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

[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 by the water-based flame retardant ink described in the above aspects or the water-based flame retardant ink prepared according to the preparation method described in the above aspects.

[0027] The water-based flame-retardant ink for PET film and the manufacturing method thereof, as well as the PET film provided by the embodiments of the present invention have at least one or part of the following advantages:

[0028] (1) The compatibility problem between directly attached PET film and flame retardant is solved by synergistically combining 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, 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 used with the cross-linking agent in the second component that has a low reaction rate at room temperature and a long activation period, the coating can be used for more than 12 hours.

[0030] (3) When applied to PET film, no pre-treatment or primer is required. A stable coating can be formed on the surface of the PET film directly through micro-concave coating and drying and aging. The surface drying speed is fast and there is no re-stickiness.

[0031] (4) The coating adhesion of the water-based flame retardant ink coating is ≥4B, the alcohol wiping resistance is ≥200 when loaded with 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 ink does not contain heavy metals, halogens and other environmentally harmful substances, and is 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 ink by screening and proportioning commercially available materials. The process is simple and the production efficiency is high, which reduces production costs;

[0034] (7) When coating on the surface of PET film, only a micro-concave coating process is required. The utilization rate of water-based flame retardant ink material is high, which can achieve rapid and continuous operation and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0036] Figure 1 Flowchart of a method for preparing a water-based flame retardant ink according to one embodiment of the present invention;

[0037] Figure 2 Based on Figure 1 A physical picture of a water-based flame retardant ink obtained by the preparation method of an embodiment;

[0038] Figure 3 For the general Figure 2 The actual picture of the obtained water-based flame retardant ink after coating on PET film. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be further described in detail below through examples and in conjunction with the accompanying drawings. In the 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 limiting the present invention.

[0040] This invention provides a water-based flame-retardant ink for PET film, a method for manufacturing the ink, and the PET film. This ink utilizes a water-dispersible modified polyester resin of a specific particle size and a water-dispersible halogen-free phosphorus flame retardant additive to address the compatibility issues of direct attachment to PET film and flame retardancy. The fully water-based formulation is safe, environmentally friendly, and has extremely low VOC emissions. Furthermore, mixing the first and second components during use effectively increases the pot life of the coating to over 8 hours. Combined with the crosslinker in the second component, which has a low reaction rate at room temperature and a long pot life, the ink can last for over 12 hours.

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

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

[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] During use, the first and second components are mixed with deionized water and then applied to the surface of the PET film material using a micro-dimpled coating method. After drying, a water-based flame retardant ink coating is formed on the surface of the PET film material, which has stable adhesion, excellent chemical corrosion resistance, scratch resistance and abrasion resistance, and achieves VT-0 flame retardancy. The high surface tension of the water-based flame retardant ink coating facilitates subsequent printing and gluing processes.

[0046] In one example, 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. This modified polyester resin exhibits excellent quick-drying properties, workability, abrasion resistance, and hardness, and exhibits excellent adhesion to various types of plastic film.

[0047] In one example, the hydroxyl value of the water-dispersible halogen-free modified polyester resin is ≤20 mg / g KOH. The water-dispersible halogen-free modified polyester resin includes a linear modified polyester resin with a number-average molecular weight of 5,000-10,000. This small amount of hydroxyl groups can chemically react with the curing agent (water-dispersible crosslinker) in the second component, improving the chemical properties of the resulting water-based flame retardant ink coating, such as resistance to alcohol and chemicals.

[0048] The water-dispersible halogen-free modified polyester resin is present in the emulsion with a primary particle size distribution range of 100-300 nm. This particle size distribution maintains the stability of the resin raw material, preventing precipitation or gelation. The finished water-based flame retardant ink and its coating form a smooth, balanced coating.

[0049] It's important to note that the water-dispersible halogen-free modified polyester resin should be present in the coating composition (the mixture of the first component) at approximately 40-80% by weight. When its content is less than 40%, the coating formed from this coating composition has low hardness and slow surface drying, leading to easy tackiness during winding. It also reduces the overall crosslink density of the coating, resulting in decreased alcohol resistance and adhesion. When its content exceeds 80%, the flame retardant effect of the coating formed from this coating composition deteriorates.

[0050] For example, the water-dispersible halogen-free modified polyester resin can be a common commercially available modified polyester resin. For example, water-based polyester resins from Toyobo (such as MD-1200, MD-1245, MD-1500, and MD-2000). Water-soluble saturated polyester resins from SK (such as EW 100G, EW 100D, EW 210, and EW 312). Water-based polyurethane dispersion resins from Mitsui (such as W-5030, WS-5000, WS-4022, and W-5661). 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 by those skilled in the art as limiting the present invention. The selection of specific component materials will be discussed in the same manner and will not be elaborated upon.

[0051] In the process of preparing the water-based flame retardant ink of the present invention, it is necessary to screen suitable modified polyester resin raw materials as water-dispersible halogen-free modified polyester resins through experiments and parameter measurements. The screening is mainly based on evaluating the adhesion of the modified polyester resin raw materials to PET.

[0052] In one example, a PET adhesion test was conducted by mixing various types of modified polyester resin raw materials at a fixed component ratio (e.g., 80%) with DMEA (amine pH regulator), BYK024 (defoaming agent), BYK348 (wetting and leveling agent), E-1011 (matting agent), and ethylene glycol butadiene glycol (film-forming agent) in deionized water, and then adding a fixed ratio of isocyanate curing agent (e.g., CSNB-W20523).

[0053] Experimental testing has shown that PA-based acrylic resins have no adhesion to PET. PUD-based polyurethane resins, with the exception of RE-2108, have no adhesion and can also cause re-sticking issues. Most commercially available PE-based polyester resins exhibit good adhesion to PET (reaching 4B standards).

[0054] Therefore, it is necessary to first screen water-based PE resins or water-dispersible PE resins from common commercially available modified polyester resin raw materials. Then, a secondary performance evaluation (primarily evaluating flame retardancy and adhesion) is performed using these screened water-based PE resins or water-dispersible PE resins mixed with flame retardants to obtain a water-dispersible halogen-free modified polyester resin suitable for preparing the water-based flame retardant inks specified in the present invention.

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

[0056] In one example, commercially available water-based PE resins mixed with APP flame retardants achieved flame retardancy but exhibited poor adhesion. MD-1200, EW 100G, and W-5030 water-based PE resins mixed with APP flame retardants achieved adhesion but exhibited tackiness. WK3108 water-based PE resins achieved both adhesion and tack-free properties, but reacted with the flame retardant to form gels after one day at room temperature. Therefore, further screening of water-dispersible halogen-free flame retardant additives is necessary.

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

[0058] The flame retardant mechanism of this water-dispersible halogen-free flame retardant additive is as follows: phosphoric anhydride forms as a dehydrating agent and promotes char formation. This char formation reduces heat transfer from the flame to the condensed phase. Phosphoric acid absorbs heat, preventing the oxidation of CO to CO2 and slowing the heating process. It forms a thin, glassy or liquid protective layer on the condensed phase, reducing oxygen diffusion and heat and mass transfer between the gas and solid phases. This inhibits the char oxidation process and reduces the thermal decomposition of the phosphorus-containing flame retardant to produce polymetaphosphoric acid. Polymetaphosphoric acid is a stable, non-volatile compound with strong dehydration properties. The released water vapor absorbs a large amount of heat, causing the flame retardant on the polymer surface to decompose upon heating, releasing volatile phosphides. Mass spectrometry analysis shows a significant reduction in the concentration of stored hydrogen atoms, indicating that PO ions capture H ions to react and form HPO.

[0059] This water-dispersible halogen-free flame retardant additive is halogen-free and can be dispersed directly into aqueous systems without the need for grinding or other processes. It typically has a number-average molecular weight of approximately 8,000-10,000 and is emulsifier-free. The polymeric dispersant's molecular chain contains hydrophilic groups that react with the crosslinker in the second component, effectively ensuring the resulting coating exhibits excellent water and chemical resistance.

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

[0061] Typically, the water-dispersible halogen-free flame retardant additive is present in the coating composition in an amount of approximately 15-35% by weight. When the content is less than 15%, the flame retardant effect of the coating formed from the coating composition deteriorates. When the content is greater than 35%, the coating formed from the coating composition has poor adhesion to the PET film, resulting in a softened coating and a tendency to cause re-sticking during winding.

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

[0063] During the preparation of the water-based flame retardant inks of the present invention, suitable water-dispersible halogen-free flame retardant additives must be screened through experiments and parameter measurements. This screening process primarily involves evaluating the flame retardancy and dispersibility of the mixture of a water-based PE resin or a water-dispersible PE resin (water-dispersible halogen-free modified polyester resin) and the water-dispersible halogen-free flame retardant additive.

[0064] In one example, water-based PE resins or water-dispersible PE resins selected through preliminary adhesion tests are mixed with a fixed component ratio (e.g., 60%) of various water-dispersible halogen-free flame retardants and DMEA (amine pH regulator), BYK024 (defoaming agent), BYK348 (wetting and leveling agent), E-1011 (matting agent), ethylene glycol butadiene glycol (film-forming agent), and AS1130 (thickener) in fixed component ratios (e.g., 20%) with deionized water, and a fixed ratio of isocyanate curing agent (e.g., CSNB-W20523) is added to test the flame retardancy, water-based system dispersibility, and anti-stickiness.

[0065] Experimental tests have shown that solid flame retardants (such as 5900 and Mg(OH)2) have excellent flame retardant effects when mixed with water-based PE resins or water-dispersible PE resins. However, their poor dispersibility in water-based systems causes particles in the coating and affects adhesion. Only HY-FR083, a liquid water-dispersible phosphorus-containing flame retardant, meets the flame retardant requirements, but it can cause re-sticking problems.

[0066] Furthermore, after screening out a better water-dispersible halogen-free flame retardant additive (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 re-sticking problem.

[0067] Furthermore, the water-dispersible halogen-free modified polyester resins selected through experimental testing generally have a glass transition temperature of 50-90°C and a particle size of 100-300 nm. Furthermore, the hydroxyl value of these water-dispersible halogen-free modified polyester resins is ≤20 KOHmg / g, including linear modified polyester resins with a number average molecular weight of 5,000-10,000.

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

[0069] Preferably, an alkali-soluble anionic thickener is used, which is an acid-containing cross-linked acrylic emulsion copolymer. This type of thickener rapidly swells the emulsion particles when diluted with water and neutralized with alkali. Polyacrylic acid-based thickeners effectively improve low-shear viscosity, imparting high shear-thinning properties to the resulting coating, ensuring excellent workability and preventing fat-edge sagging.

[0070] For example, the thickener may be a common commercially available material, such as 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 cross-linking agent in the second component is an aziridine compound, and the aziridine compound has an activation period of greater than or equal to 8 hours.

[0072] Typically, the second component, forming the curing agent, is added to the first component at a weight ratio of 3-10%. The two components are thoroughly mixed before coating. If the second component curing agent content is less than 3%, the coating's resistance to chemicals like alcohol will deteriorate. If this content exceeds 10%, the coating becomes too hard, poorly adhering to the PET film, and the pot life will be shortened.

[0073] For example, the water-dispersible crosslinking agent (aziridine compound) can be a commercially available common polyurethane resin material, such as CX-100 from Covestro, P350 from Haoyi, DK100 from Deck Biotechnology, HS-100A from Lingsui, and SaC-100 from Youen.

[0074] In one example, preferably, the water-based flame retardant ink is applied to the surface of the PET film by micro-dimpled 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, an alcohol wipe resistance of ≥200 times under a load of 500 g, and a flame retardant grade of VT-0.

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

[0076] See also Figure 1 , showing the specific process steps of the preparation method. The preparation method includes:

[0077] Step S101: preparing a first component, filtering a water-dispersible halogen-free modified polyester resin, a water-dispersible halogen-free flame retardant additive, and a quick-drying solvent through a 300-mesh filter, mixing the mixture, and stirring the mixture at a speed of 200-600 rpm for 10-20 minutes;

[0078] Step S102: adding defoaming agent, wetting and leveling agent, film-forming agent, pH regulator, thickener and matting agent in sequence and stirring and filtering simultaneously until the fineness is ≤5μm;

[0079] Step S103: preparing a second component by mixing an aziridine cross-linking agent with an ester solvent;

[0080] Step S104: Before use, the first component and the second component are mixed at a mass fraction of 100:(3-10), and 5-10 wt% deionized water is added 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-dimpled coating followed by aging treatment.

[0082] In one example, specifically, in step S102, the defoaming agent and the wetting and 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 aging process includes:

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

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

[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 by the water-based flame retardant ink described in the above aspects or the water-based flame retardant ink prepared according to the preparation method described in the above aspects.

[0087] Example 1

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

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

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

[0091] After obtaining the above-mentioned first component and second component, 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 additive and alcohol in the above ingredients according to weight percentage, filter them with 300 mesh filter cloth, add them into a stainless steel mixing tank, and stir them with a disperser at a speed of 200-400 rpm for 10-20 minutes.

[0093] 2. Weigh BYK 024 and BYK 348 in the first component according to the weight percentage respectively, 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. Scrape the fineness plate to ensure that there are no shrinkage holes, particles or other abnormalities.

[0094] 3. Weigh the ethylene glycol butyl ether in the first component according to the weight percentage, mix it evenly with deionized water in a weight ratio of 1:1, reduce the speed of the disperser to 200-400 rpm, filter 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 and mix it evenly with deionized water in a weight ratio of 1:1. Since this process will release heat, it needs to be cooled to room temperature. Use a 300-mesh filter cloth to filter while dispersing and stirring, and then add it to a stainless steel mixing tank.

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

[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. Continue to disperse and stir for 10-20 minutes, scrape the fineness plate to confirm the fineness, and measure the pH value, viscosity and fixed component content to see if they meet the standards.

[0099] When a coating is required on 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 to dilute and filter to form a water-based flame retardant ink; when in use, the water-based flame retardant ink coating is formed by micro-dimpled coating and then aging treatment.

[0100] Specifically, in this embodiment, the first component, the second component, and deionized water are preferably stirred and mixed at a mass ratio of 100:5:5-10, and then filtered through a 300-mesh nylon mesh. Micro-dimpled coating is then performed on the machine without a primer. The water-based flame retardant ink is applied to the PET film substrate using a roller, with the coating thickness reaching 13-15 μm.

[0101] After coating, the film is baked in a hot air oven at 110-120°C for 60-120 seconds to achieve surface drying without re-sticking. After surface drying, the film is rolled up and placed in an oven at 50±2°C for 24 hours to cure. Performance testing is then performed, resulting in a transparent PET film with a base thickness of 0.025 mm.

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

[0103] Table 1 Index test results of water-based flame retardant ink of Example 1

[0104]

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

[0106]

[0107] It can be seen from the test results in Table 1 and Table 2 that the water-based flame retardant ink of the embodiment of the present invention is superior to commercial products in various core properties.

[0108] The water-based flame-retardant ink for PET film and the manufacturing method thereof, as well as the PET film provided by the embodiments of the present invention have at least one or part of the following advantages:

[0109] (1) The compatibility problem between directly attached PET film and flame retardant is solved by synergistically combining 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, 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 used with the cross-linking agent in the second component that has a low reaction rate at room temperature and a long activation period, the coating can be used for more than 12 hours.

[0111] (3) When applied to PET film, no pre-treatment or primer is required. A stable coating can be formed on the surface of the PET film directly through micro-concave coating and drying and aging. The surface drying speed is fast and there is no re-stickiness.

[0112] (4) The coating adhesion of the water-based flame retardant ink coating is ≥4B, the alcohol wiping resistance is ≥200 when loaded with 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 ink does not contain heavy metals, halogens and other environmentally harmful substances, and is 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 ink by screening and proportioning commercially available materials. The process is simple and the production efficiency is high, which reduces production costs;

[0115] (7) When coating on the surface of PET film, only a micro-concave coating process is required. The utilization rate of water-based flame retardant ink material is high, which can achieve rapid and continuous operation and improve production efficiency.

[0116] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art 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 in the claims and their equivalents.

Claims

1. A water-based flame-retardant ink for PET film, characterized in that: The water-based flame retardant ink comprises: The first component comprises, by mass fraction, 40-80 wt % of a water-dispersible halogen-free modified polyester resin, 20-40 wt % of a water-dispersible halogen-free flame retardant additive, 5-10 wt % of a quick-drying solvent, 0.3-0.5 wt % of a defoaming agent, 0.3-0.5 wt % of a wetting and leveling agent, 5-10 wt % of a film-forming aid, 0.5-2 wt % of an alkali-soluble anionic thickener, and 5-10 wt % of a matting aid, with the remainder being deionized water; a second component comprising, by mass fraction, 40-70 wt % of a water-dispersible crosslinking agent and 30-60 wt % of an ester solvent; 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, characterized in that: 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 additive is a phosphorus-containing polymer dispersion, the phosphorus content of the phosphorus-containing polymer dispersion is 6-8wt%, and the particle size is 200-500nm.

3. The water-based flame retardant ink according to claim 2, characterized in that: 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 comprises a linear straight-chain modified polyester resin with a number average molecular weight of 5000-10000.

4. The water-based flame retardant ink according to any one of claims 1 to 3, characterized in that: The matting agent in the first component is a silicon dioxide matting powder with a particle size of 3-8 μm; The thickener in the first component is an acid-containing cross-linked acrylic emulsion copolymer; The quick-drying solvent in the first component is ethanol or isopropanol.

5. The water-based flame retardant ink according to claim 4, characterized in that: The water-dispersible cross-linking agent in the second component is an aziridine compound, and the aziridine compound has an activation period of greater than or equal to 8 hours.

6. The water-based flame retardant ink according to claim 5, characterized in that: The water-based flame retardant ink is applied to the surface of a PET film by micro-dimpled 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, an alcohol wipe resistance of ≥200 times under a load of 500 g, and a flame retardant grade of VT-0.

7. A method for preparing a water-based flame retardant ink for PET film, the method being used to prepare the water-based flame retardant ink according to any one of claims 1 to 6, characterized in that: The preparation method comprises: Step S101: preparing a first component, filtering a water-dispersible halogen-free modified polyester resin, a water-dispersible halogen-free flame retardant additive, and a quick-drying solvent through a 300-mesh filter, mixing the mixture, and stirring the mixture at a speed of 200-600 rpm for 10-20 minutes; Step S102: adding defoaming agent, wetting and leveling agent, film-forming agent, pH regulator, thickener and matting agent in sequence and stirring and filtering simultaneously until the fineness is ≤5μm; Step S103: preparing a second component by mixing an aziridine cross-linking agent with an ester solvent; Step S104: before use, the first component and the second component are mixed at a mass fraction of 100:(3-10), and 5-10 wt% deionized water is added to dilute and filter to form a water-based flame retardant ink; Step S105: When in use, a water-based flame retardant ink coating is formed by micro-dimpled coating followed by aging treatment.

8. The preparation method according to claim 7, characterized in that In step S102, the defoaming agent and the wetting and leveling agent are slowly added to the mixed raw materials in step S101 at a rotation speed of 400-600 rpm.

9. The preparation method according to claim 7, characterized in that In step S105, the aging process specifically includes: After coating the water-based flame retardant ink on the surface of the PET film, the film is dried with hot air at a temperature of 110-120° C. for 60-120 seconds; After drying, the mixture was aged at 50±2° C. for 24 hours to obtain a water-based flame retardant ink coating with a dry film thickness of 13-15 μm.

10. A PET film, characterized in that: 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 to 6 or the water-based flame retardant ink prepared by the preparation method according to any one of claims 7 to 9.

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