High-coverage black ink as well as preparation method and application thereof

Abstract

The invention relates to high-coverage black ink as well as a preparation method and application thereof. The ink comprises the following components in parts by mass: 40-70 parts of hydroxy acrylic resin, 10-30 parts of polycarbonate polyol, 1-10 parts of polycaprolactone polyol, 40-70 parts of black pigment, 2-15 parts of high-refractive-index pigment, 15-40 parts of a curing agent and 15-45 parts of a dispersing agent. Compared with the prior art, the coating has the advantages of good thermal tensile property, excellent weather resistance and thermal aging property, high covering power, deep black and good adhesiveness to a plastic substrate.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of ink, and relates to a high-hiding black ink as well as a preparation method and application thereof. BACKGROUND

[0002] With the increasing requirements for product appearance quality and durability in the fields of automobiles, home appliances, consumer electronics and the like, an in-mold structuring (INS) process, as an advanced manufacturing technology combining printing decoration and injection molding, is increasingly valued. The in-mold structuring process synchronously forms an ink layer printed by gravure coating technology and a substrate in the molding process, thereby realizing the manufacturing of complex textures and fine patterns, and improving the overall design degree and product appearance effect.

[0003] At present, the in-mold structuring ink technology has made certain progress in formula design, rheological control and drying and curing and the like. In particular, in the development of high-hiding black ink, the industry generally adopts an improved carbon black dispersion system, supplemented by a special resin system and functional additives, aiming to realize high hiding power and uniform coloring effect under low coating amount, while taking into account the heat resistance, scratch resistance and adhesion of the ink. For example, patent CN118745298A proposes a high-hiding ink using a modified carbon black dispersion technology, which improves the uniformity of the ink while improving the tinting power. Patent CA2759350A1 proposes a black ink suitable for high-temperature injection molding, which maintains a deep black while having excellent heat resistance and adhesion. Patent CN114656837A discloses a high-hiding high-insulation black ink and a preparation method thereof, which uses acrylic resin in combination with carbon black to realize a very high color density value by controlling the particle size and proportion of carbon black.

[0004] However, the traditional ink still faces many technical challenges in the application of the in-mold structuring process: while pursuing high hiding power, too high pigment load in the ink may lead to poor rheological properties, thereby affecting the uniformity of gravure coating and the stability of the ink layer after molding; in addition, the ink is prone to micro-cracks or peeling during the high-temperature and high-stress injection molding process, thereby reducing the product appearance quality. Therefore, it is urgent to develop a high-hiding black ink that meets the requirements of thin film uniformity and high hiding of the in-mold structuring process, and has excellent heat resistance, heat stretching and weather resistance. SUMMARY

[0005] The present application is to overcome at least one of the above-mentioned defects in the prior art, and provides a high-hiding black ink as well as a preparation method and application thereof. The present application has good heat stretching performance, excellent weather resistance and heat aging performance, high hiding power, deep black color and good adhesion to plastic substrates.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present application is to provide a high-covering black ink, which comprises the following components by mass fraction:

[0008] 40-70 parts of hydroxyl acrylic resin, 10-30 parts of polycarbonate polyol, 1-10 parts of polycaprolactone polyol, 40-70 parts of black pigment, 2-15 parts of high refractive index pigment, 15-40 parts of curing agent and 15-45 parts of dispersing agent.

[0009] The mixed system of the hydroxyl acrylic resin, the polycarbonate polyol and the polycaprolactone polyol can ensure the mechanical strength of the ink and provide sufficient flexibility and low-temperature impact resistance during high-temperature injection molding, so that the ink can form a uniform and dense coating on various substrate surfaces.

[0010] Further, the hydroxyl value of the hydroxyl acrylic resin is 20-130 mg KOH / g, which can ensure the durability of the cured film when higher than the lower limit, and can ensure the plasticity of the cured film when lower than the upper limit, the secondary preferred value is 30-120 mg KOH / g, and the more preferred value is 40-110 mg KOH / g,

[0011] The primary hydroxyl group ratio is not less than 60%, which has higher reactivity with the curing agent compared with the secondary or tertiary hydroxyl group, and when the ratio of the primary hydroxyl group increases, it is difficult for unreacted components to remain in the cured coating, and the wear resistance and sun protection are improved, the secondary preferred value is not less than 75%, and the more preferred value is not less than 80%,

[0012] From the durability and the dispersibility of the pigment, the hydroxyl acrylic resin needs to have a certain acid value, and at the same time, the reaction between the hydroxyl group and the curing agent can be promoted by the carboxylic acid, so that a cured film with high durability can be obtained, the acid value is 1-15 mg KOH / g, which can improve the durability without affecting the moldability, the secondary preferred value is 1-8 mg KOH / g, and the more preferred value is 2-6 mg KOH / g,

[0013] In order to meet the requirements of flexibility, i.e. hot tensile rate and heat aging performance, the glass transition temperature (Tg) is 40-90℃, the secondary preferred value is 45-85℃, and the more preferred value is 50-80℃;

[0014] The molecular weight of the polycarbonate polyol is 500-5000, the secondary preferred value is 1000-3000, and the more preferred value is 1500-2500,

[0015] The hydroxyl value is 30-200 mg KOH / g, which can ensure flexibility and heat resistance, preferably 40-150 mg KOH / g, more preferably 50-120 mg KOH / g;

[0016] The molecular weight of the polycaprolactone polyol is 600-2000, which is higher than the lower limit, and when the polycaprolactone polyol is crosslinked, sufficient spacing is maintained between the crosslinking points, so that the elongation property and wear resistance are excellent, and when the molecular weight is lower than the upper limit, the polycaprolactone polyol is fully compatible with the ink, and the polycaprolactone polyol is uniformly dispersed in the ink, so that appearance defects such as reduction in transparency do not occur, preferably 700-1700, more preferably 800-1500,

[0017] Based on the above conditions, the hydroxyl value is 50-300 mg KOH / g, preferably 70-200 mg KOH / g, more preferably 80-160 mg KOH / g.

[0018] As a preferred technical solution, the hydroxyl acrylate resin is obtained by copolymerization of a hydroxyl-containing monomer and a monomer without a hydroxyl group,

[0019] The monohydroxy monomer is selected from one or more of hydroxyalkyl (meth) acrylate and its ε-caprolactone adduct, wherein the hydroxyalkyl methacrylate is preferably one or more of hydroxyethyl methacrylate (HEMA) and hydroxypropyl methacrylate (HPMA), and the side chain of the monohydroxy monomer contains only one hydroxyl group, which is more easily diffused between molecules during crosslinking reaction with the curing agent, and a uniform crosslinking network is constructed, and the monohydroxy system gives the coating film excellent wear resistance and chemical resistance,

[0020] The polyhydroxy monomer is selected from one or more of polyhydroxyalkyl (meth) acrylate and its ε-caprolactone adduct, wherein the dihydroxyalkyl methacrylate is preferably one or more of 1,1-dihydroxymethyl methacrylate and 1,2-dihydroxyethyl methacrylate, and the side chain hydroxyl of the polyhydroxy monomer is aggregated, and the crosslinking reaction is easily localized within a single side chain, and even if intermolecular crosslinking occurs, the crosslinking network is uneven due to the local enrichment of hydroxyl groups, resulting in a decrease in the mechanical properties (such as hardness and toughness) of the polyhydroxy system, but because the distance between the crosslinking points is larger, the molecular chain moves more freely, and the forming and processing performance (such as flowability and forming efficiency) of the polyhydroxy system is better than that of the monohydroxy system,

[0021] When the hydroxyl value of the copolymer is similar, the local enrichment effect of the polyhydroxy system is more prominent, and the performance difference is further amplified; in order to balance the wear resistance / chemical resistance / mechanical properties and forming and processing performance, the proportion of the monohydroxy monomer in the hydroxyl-containing monomer is not less than 65wt%,

[0022] To meet the requirements of flexibility, i.e. hot tensile rate, and heat aging performance, the hydroxyl acrylic resin is obtained by copolymerization of hard monomers and soft monomers without hydroxyl groups, and hydroxyl-containing monomers, the hard monomers are monomers with a glass transition temperature not lower than -10℃, preferably one or more of methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, the soft monomers are monomers with a glass transition temperature less than -10℃, preferably one or more of ethyl acrylate, n-butyl acrylate, lauryl acrylate, lauryl methacrylate, n-octyl methacrylate, the proportion of the hard monomers is 45-70wt%, the proportion of the soft monomers is 10-25wt%, the proportion of the hydroxyl-containing monomers is 10-25wt%, and the proportion of the remaining functional monomers is 1-5wt%, the reasonable collocation of the hard monomers and the soft monomers makes the glass transition temperature 40-90℃,

[0023] The hydroxyl acrylic resin accounts for not less than 50wt% of the total resin content, preferably not less than 60wt%;

[0024] The polycarbonate polyol is selected from one or more of aliphatic polycarbonate polyols, aromatic polycarbonate polyols, and mixed polycarbonate polyols, wherein the aliphatic polycarbonate polyol is preferably one or more of polycarbonate hexylene glycol, polycarbonate-1,6-hexanediol glycol, polycarbonate caprolactone hexylene glycol, polycarbonate butylene glycol, polycarbonate cyclohexane dimethylol-1,6-glycol, polycarbonate-1,5-pentanediol-1,6-hexanediol glycol, polycarbonate-1,4-butanediol-1,6-hexanediol glycol, and polycarbonate-2-octanol glycol,

[0025] The polycarbonate polyol accounts for 5-35wt% of the total resin content, preferably 10-25wt%;

[0026] The polycaprolactone polyol has two to five hydroxyl groups (OH) in one molecule, and molecules with different numbers of hydroxyl groups can be used alone or in mixture, since the polycaprolactone polyol contains two or more hydroxyl groups in one molecule, the crosslinking reaction with the hydroxyl-containing monomers of the hydroxyl acrylic resin is fully carried out, if the polycaprolactone polyol contains three or more hydroxyl groups in one molecule, the crystallinity of the polycaprolactone polyol is small, and the compatibility with the ink is better, so it can be more uniformly dispersed in the ink, and the appearance defect of the resin film containing the ink does not occur, if the polycaprolactone polyol contains five or fewer hydroxyl groups in one molecule, the crosslinking density is within an appropriate range, and the elongation of the ink can be fully maintained,

[0027] The polycaprolactone polyol accounts for 1-15 wt% of the total content of the resin. If the addition amount of polycaprolactone polyol is too much, it may cause ink layer thermal aging and decrease in solvent resistance, preferably 2-8 wt%.

[0028] According to the Furnas model (bimodal particle packing theory):

[0029] Φ total = Φ large (1-Φ large )×Φ small

[0030] Wherein, Φ large is the packing volume fraction of large particles, and Φ small is the filling volume fraction of small particles in the remaining pores;

[0031] Introducing a certain amount of high refractive index large particles into the black pigment can effectively improve the compactness of the entire coating, and has a synergistic effect on hiding power, weather resistance and cost control.

[0032] Further, the black pigment is selected from one or more of carbon black, aniline black, titanium black, iron oxide black, and perylene black,

[0033] The specific surface area of the black pigment is 120-400 m 2 / g, preferably 150-360 m 2 / g,

[0034] The primary particle size is 5-60 nm, preferably 10-40 nm,

[0035] The oil absorption value (DBP) is 80-240 mL / 100g, preferably 90-200 mL / 100g,

[0036] The secondary particle size D 50 is 10-100 nm, D 90 is 0.06-0.5 μm, which ensures long-term dispersion stability. The black pigment in this range has excellent light absorption effect and meets the demand for high hiding. The secondary particle size D 50 is preferably 30-80 nm, and D 90 is preferably 0.08-0.3 μm;

[0037] The high refractive index pigment is selected from one or more of magnetite (refractive index = 2.42), rutile titanium dioxide (refractive index = 2.76), anatase titanium dioxide (refractive index = 2.52), zirconium oxide (refractive index = 2.05), cerium oxide (refractive index = 2.2), zinc oxide (refractive index = 2.1), aluminum nitride (refractive index = 1.9-2.2), tungsten oxide (refractive index = 2.2), aluminum oxide (refractive index = 1.9-2.2), and the like. When light encounters these high refractive index particles, it is reflected and scattered in large quantities, thereby effectively blocking the underlying color from shining through and enhancing hiding power.

[0038] To ensure proper pore size, the secondary particle size D 50 The high refractive index pigment has a secondary particle size D

[0039] As a preferred technical solution, based on the above description, the proportion of the pigment in the entire coating is 12-36 wt% of the total solid mass. Considering the heat stretchability, hydrolysis resistance, and heat aging and light aging requirements of the coating, the less preferred proportion is 17-32 wt%, and the more preferred proportion is 20-30 wt%.

[0040] From the economic and performance considerations, the black pigment is carbon black,

[0041] From the perspective of high hiding power, coloring, and blackness, the less preferred black pigment is medium-high pigment carbon black,

[0042] The more preferred black pigment is high pigment carbon black, which has extremely high light absorption (>99%) and can effectively absorb light to ensure that the ink appears dark black.

[0043] The high refractive index pigment is titanium dioxide. In combination with carbon black and titanium dioxide, carbon black absorbs light to achieve hiding and fill the gaps between titanium dioxide particles, forming a dense layer and reducing the light scattering path. Titanium dioxide, which forms the skeleton structure, enhances hiding efficiency by reflecting / scattering light, thereby improving hiding power. Moreover, titanium dioxide reflects UV (280-400 nm), which can reduce the photodegradation of the resin matrix to some extent.

[0044] From the aspects of weather resistance, refractive index, and cost, the high refractive index pigment is preferably rutile titanium dioxide, which has a high refractive index and excellent scattering performance and can synergistically form a multi-level particle filling structure with the black pigment. Large rutile titanium dioxide particles reflect / scatter light (especially visible light with a wavelength of 400-700 nm) through Mie scattering, and the scattering efficiency is related to the particle size / wavelength ratio (optimal d≈λ / 2 d≈λ / 2).

[0045] The addition amount of the high refractive index pigment is 5-30wt% of the black pigment. Within this range, the high refractive index pigment and the black pigment have good bulk density to improve the compactness of the coating, and the amount of the black pigment can be reduced to avoid the viscosity surge caused by high concentration of the black pigment, and the printing suitability is improved. When the amount of the high refractive index pigment is too low, the high refractive index pigment cannot play a proper synergistic effect. When the amount of the high refractive index pigment is too high, the reflected light of the high refractive index pigment competes with the light absorption of the black pigment, resulting in that part of the light is not absorbed, and the entire coating appears gray. To achieve good hiding power, the amount of the high refractive index pigment is preferably 10-25wt%, and more preferably 15-20wt%.

[0046] Further, the curing agent is selected from one or more compounds having two or more isocyanate groups (NCO) in one molecule, or a trimer or a multimer composed of the same, of an aromatic isocyanate, an aliphatic isocyanate, and a cycloaliphatic isocyanate, the aromatic isocyanate is selected from one or more difunctional aromatic isocyanates of toluene-2,4-diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), m-tetramethylxylene diisocyanate (m-TMXDI), naphthalene-1,5-diisocyanate (NDI), and p-phenylene diisocyanate (PPDI), the aliphatic isocyanate is selected from one or more difunctional aliphatic isocyanates of hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and trimethylhexamethylene diisocyanate (TMDI), and the cycloaliphatic isocyanate is selected from one or more difunctional cycloaliphatic isocyanates of dicyclohexylmethane-4,4'-diisocyanate (HMDI) and isophorone diisocyanate (IPDI).

[0047] As a preferred technical solution, from the perspective of heat resistance and anti-yellowing, the curing agent is selected from one or more difunctional isocyanates without benzene ring and with higher crosslinking density of hexamethylene diisocyanate trimer, dicyclohexylmethane-4,4'-diisocyanate trimer, and hexamethylene diisocyanate trimer,

[0048] The isocyanate group content of the curing agent is 10-30wt%.

[0049] As a preferred technical solution, the dispersant is not limited, and one or more of commercially available polyester type, polyurethane type, acrylic type, and block copolymer type dispersants or super dispersants can be selected, and preferably one or more of Efka4310, BYK-163, BYK-2013, Lubrizol 24000, and Lubrizol 32500 is selected.

[0050] The amount of the dispersant is 2mg / m2 of the surface area of the pigment, calculated based on the active content of the dispersant. 2The particle size can be adjusted according to the selected pigment or resin, and the particle size should meet the requirements of the pigment.

[0051] Further, the ink further comprises 0.3-1.5wt% of silane coupling agent relative to the solid mass, the silane coupling agent forms a chemical bond between the pigment and the resin, effectively improving the interface bonding, reducing the risk of micro-cracks caused by the difference in thermal expansion coefficient, and improving the scratch resistance and solvent resistance of the ink.

[0052] As a preferred technical solution, the silane coupling agent is selected from one or more of KH-570, Mitsui Silquest A-1891, Wincell Dynasylan 1189, and Shin-Etsu KBE-60.

[0053] Further, the ink further comprises 150-300wt% of a solvent relative to the solid mass, the solvent is selected from one or more of toluene, ethyl acetate, butanone, butyl acetate, N,N-dimethylformamide, propylene glycol methyl ether acetate (PMA), methyl ethyl ketone (MEK), and isophorone;

[0054] In order to improve the workability of the ink, the ink further comprises 0.1-0.5wt% of a catalyst relative to the solid mass, the catalyst is selected from one or more of tetramethylbutanediamine, triethylenediamine, stannous octoate, dibutyltin dilaurate, lead octoate, cobalt octoate, iron octoate, zinc naphthenate, and titanium acid tetraisobutyl ester;

[0055] In order to improve the weather resistance of the ink, the ink further comprises 0.5-2.5wt% of a light absorber relative to the solid mass;

[0056] In order to improve the weather resistance of the ink, the ink further comprises 0.5-2.5wt% of a light stabilizer relative to the solid mass, to prolong the service life of the ink;

[0057] Based on the coating needs, the ink further comprises 0.05-0.3wt% of a leveling agent relative to the solid mass;

[0058] Based on the coating needs, the ink further comprises 0.05-0.3wt% of a defoaming agent relative to the solid mass.

[0059] As a preferred technical solution, the light absorber is selected from one or more of Tinuvin 1130, Tinuvin 479, Tinuvin 460, and Tinuvin 400 ultraviolet absorbers;

[0060] The light stabilizer is selected from one or more of Tinuvin 622, Tinuvin 292, Tinuvin 123, and Tinuvin 770DF hindered amine light stabilizers;

[0061] The leveling agent is selected from one or more of BYK-333, BYK-331, BYK-215, TEGO Glide 410, TEGO Glide 450;

[0062] The defoaming agent is selected from one or more of BYK-141, BYK-144, TEGO Airex 900, TEGO Airex 920.

[0063] One of the technical solutions of the present application is to provide a preparation method of the high-hiding black ink, which comprises the following steps:

[0064] S1.1, part of the resin and dispersant are mixed with black pigment and sanding pre-dispersed to obtain a black pigment dispersion system;

[0065] S1.2, the remaining resin and dispersant are mixed with high refractive index pigment and sanding pre-dispersed to obtain a high refractive index pigment dispersion system;

[0066] S1.3, the two pigment dispersion systems are mixed uniformly, and a curing agent is added to obtain a mixed system;

[0067] S1.4, silane coupling agent, catalyst, light absorber, light stabilizer, leveling agent and defoaming agent are added to the mixed system, and a solvent is added to obtain a high-hiding black ink.

[0068] Further, the addition ratio of the resin and the dispersant in step S1.1 is 60-90wt%;

[0069] The input energy of sanding in steps S1.1 and S1.2 is 55-100kJ / kg;

[0070] In step S1.3, the curing agent is added, so that the molar ratio of isocyanate groups of the curing agent to hydroxyl groups of the resin is (1.05-1.1):1;

[0071] In step S1.4, the solvent is added to adjust the viscosity of the ink to 2000-4000cP.

[0072] One of the technical solutions of the present application is to provide an application of the high-hiding black ink in an insert injection molding (INS) film, the insert injection molding film comprising a protective layer, an ink layer, an adhesive layer and a substrate layer in sequence, and a preparation method of the insert injection molding film comprising the following steps:

[0073] S2.1, gravure coating the high-hiding black ink on the carrier film coated with the protective layer to form an ink layer;

[0074] S2.2, gravure coating adhesive on the ink layer to form an adhesive layer, and curing to obtain a thermal transfer film;

[0075] S2.3, hot pressing the thermal transfer film and the substrate layer, wherein the adhesive layer of the thermal transfer film is in contact with the substrate layer, and the adhesive layer is activated under the action of temperature and pressure to firmly adhere to the substrate layer, the carrier film is removed, and the protective layer and the ink layer are adhered to the surface of the substrate layer under the action of the adhesive layer to form an insert injection film piece with high covering black ink.

[0076] As an optional technical solution, a remaining pattern layer, such as a wood grain or a mirror effect, can also be designed between the ink layer and the protective layer as needed.

[0077] As an optional technical solution, the protective layer coating is gravure coated on the carrier film before step S2.1.

[0078] As an optional technical solution, the high covering black ink is gravure coated on the protective layer in step S2.1.

[0079] Further, the thickness of the ink layer in step S2.1 is 1-10 μm.

[0080] As a preferred technical solution, the thickness of the ink layer in step S2.1 is 2-6 μm.

[0081] Compared with the prior art, the present application has the following beneficial effects:

[0082] (1) The high covering black ink provided by the present application can form a uniform, dense, high covering contrast and deep black ink layer in the gravure coating process by optimizing the pigment system and adjusting the ratio of the resin system, while maintaining good thermal stretching, adhesion and heat resistance and aging resistance during the injection molding process. Not only does it solve the contradiction between traditional ink and thin layer coating, but it also provides reliable technical support for realizing high-quality insert injection molding process, realizes printing and decoration integration, is suitable for surface decoration in the fields of automobiles, household appliances, consumer electronics and high-end packaging, and has a broad industrial application prospect.

[0083] (2) The present application uses hydroxy acrylic resin, polycarbonate polyol and polycaprolactone polyol as ink adhesive resin, the hydroxy acrylic resin provides performance, the polycarbonate polyol helps to improve heat resistance and flexibility, the polycaprolactone polyol optimizes stretching, and after adding dispersants, silane coupling agents, catalysts, light absorbers, light stabilizers, leveling agents and defoaming agents and other auxiliary agents, the curing agent is crosslinked to form a dense three-dimensional network structure, so that the ink after curing can still form a deep black, uniform coating under the condition of low coating amount, with high covering contrast and color stability.

[0084] (3) The ink layer after curing in the present application is resistant to high temperature and aging, and has a small color difference after long-term use, meeting the use requirements under high-temperature injection molding and long-term aging conditions;

[0085] (4) The ink in the present application has excellent rheological property and adhesion in the film forming process through the joint action of the dispersant, the silane coupling agent, the pigment and the resin, and reduces surface defects caused by pigment aggregation;

[0086] (5) The formula of the present application optimizes the proportion of black pigment and high refractive index pigment, and the two realize the reduction of the amount of black pigment while ensuring high density and hiding effect, thereby reducing production cost and improving economic benefit. BRIEF DESCRIPTION OF DRAWINGS

[0087] Figure 1 It is a structural schematic view of the embedded sheet injection film in the embodiment of the present application.

[0088] Mark explanation in the figure:

[0089] 1 - carrier film, 2 - protective layer, 3 - ink layer, 4 - adhesive layer, 5 - base material layer. DETAILED DESCRIPTION

[0090] The present application will be described in detail below in combination with specific embodiments. The present embodiment is implemented on the premise of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following embodiments.

[0091] The equipment used in the following embodiments represents conventional equipment in the art unless otherwise specified; the reagents used represent commercially available products or are prepared by conventional methods in the art unless otherwise specified, and the methods not described in detail in the following embodiments can be realized by conventional experimental methods in the art.

[0092] Example 1:

[0093] A high-hiding black ink, and the specific components are as follows:

[0094] Hydroxy acrylic resin (methyl methacrylate 50 wt%, cyclohexyl methacrylate 15 wt%, n-butyl acrylate 15 wt%, hydroxyethyl methacrylate (HEMA, primary hydroxyl) 12 wt%, 1,1-dimethylol methacrylate 3 wt%, vinyl triethoxysilane (VTES) 3 wt%, and isobutene acryloyl urea (UBAE) 2 wt%) with a mass fraction of 60 parts, a hydroxyl value of 76 mg KOH / g, a primary hydroxyl ratio of 100%, an acid value of 5 mg KOH / g, and a glass transition temperature (Tg) of 64℃;

[0095] Polycarbonate diol (PCD), 15 parts by mass, molecular weight 1500, hydroxyl value 56 mg KOH / g;

[0096] Polycaprolactone diol (PCL), 5 parts by mass, molecular weight 1000, hydroxyl value 113 mg KOH / g;

[0097] High pigment black carbon black, 56 parts by mass, specific surface area 180 m 2 / g, primary particle size 25 nm, oil absorption value (DBP) 110 mL / 100 g, secondary particle size D 50 60 nm, D 90 0.14 μm;

[0098] Rutile titanium white, 8 parts by mass, secondary particle size D 50 240 nm;

[0099] Curing agent hexamethylene diisocyanate (HDI) trimer, 21 parts by mass, isocyanate group (NCO) content 21.8 wt%;

[0100] Dispersant BYK-163, 40 parts by mass, active content 50 wt%;

[0101] Silane coupling agent KH-570, 1 part by mass;

[0102] Solvent, 400 parts by mass, mass ratio of propylene glycol methyl ether acetate (PMA) to methyl ethyl ketone (MEK) 1:1;

[0103] Catalyst dibutyl tin dilaurate, 0.5 parts by mass;

[0104] Light absorber Tinuvin 460, 1.5 parts by mass;

[0105] Light stabilizer Tinuvin 622, 1.5 parts by mass;

[0106] Leveling agent BYK-333, 0.2 parts by mass;

[0107] Defoaming agent BYK-141, 0.2 parts by mass.

[0108] The preparation method of the above high-hiding black ink, the specific steps are as follows:

[0109] S1.1, in a sanding device, 80 wt% resin and dispersant, and high pigment carbon black are added, and the sanding energy input is controlled at 58 kJ / kg, so that the secondary particle size D 50 of the carbon black is stably controlled at 60-70 nm, and a carbon black dispersion system is obtained;

[0110] S1.2、Similarly, in the sand mill, the remaining 20wt% resin and dispersant, and rutile titanium dioxide are added, and the sand mill energy input is controlled at 58 kJ / kg, so that the titanium dioxide secondary particle size D 50 The stable control is at 240-260 nm, and the titanium dioxide dispersion system is obtained;

[0111] S1.3、The two pigment dispersion systems are mixed uniformly using a shear emulsification dispersing machine, and a curing agent is added, and the molar ratio of isocyanate groups of the curing agent to hydroxyl (OH) groups of the resin is controlled at (1.05-1.1):1, to obtain a mixed system;

[0112] S1.4、Silane coupling agent, catalyst, light absorber, light stabilizer, leveling agent and defoaming agent are added to the mixed system, and solvent is added to adjust the viscosity of the ink to 3000 cP, to obtain a high hiding black ink.

[0113] The above high hiding black ink is applied in an insert injection (INS) film, as shown in Figure 1 The insert injection film sequentially comprises a protective layer 2, an ink layer 3, an adhesive layer 4 and a substrate layer 5, and the preparation method of the insert injection film comprises the following specific steps:

[0114] S2.1、A micro-embossing coater is used to coat a protective layer coating on a 30 μm thin polyethylene terephthalate (PET) carrier film 1, the coating roller is a 45 line screen roller, the coating machine oven temperature is 150°C, and the coating speed is 30 m / min, to form a 15 μm protective layer 2;

[0115] S2.2、A micro-embossing coater is used to coat a high hiding black ink on the protective layer 2, the coating roller is a 120 line screen roller, the coating machine oven temperature is 150°C, and the coating speed is 30 m / min, to form a 6 μm ink layer 3;

[0116] S2.3、A micro-embossing coater is used to coat an adhesive on the ink layer 3, the coating roller is a 90 line screen roller, the coating machine oven temperature is 140°C, and the coating speed is 30 m / min, to form a 10 μm adhesive layer 4, which is cured at 80°C for 24 h to obtain a thermal transfer film;

[0117] S2.4、A thermal laminator is used to thermally press laminate the thermal transfer film and the plastic substrate layer 5, wherein the adhesive layer 4 of the thermal transfer film is in contact with the substrate layer 5, the thermal pressing temperature is 200°C, the thermal pressing pressure is 5 MPa, and the thermal pressing laminating speed is 2 m / min, the adhesive layer 4 is activated and firmly adhered to the substrate layer 5 under the action of temperature and pressure, and the carrier film 1 is removed, the protective layer 2 and the ink layer 3 are adhered to the surface of the substrate layer 5 under the action of the adhesive layer 4, to form an insert injection film with high hiding black ink.

[0118] Example 2:

[0119] A high hiding black ink, substantially the same as Example 1, except that a different type of hydroxyl acrylic resin is used, i.e.

[0120] A hydroxyl acrylic resin (isobornyl methacrylate 45 wt%, cyclohexyl methacrylate 20 wt%, ethyl acrylate 20 wt%, hydroxyethyl methacrylate 6.37 wt%, hydroxypropyl methacrylate 2.63 wt%, 1,1-dimethylol methacrylate 4 wt%, vinyl triethoxy silane 1 wt% and isobutyryloxy ethyl urea 1 wt%) having a mass fraction of 60 parts, a hydroxyl value of 57.5 mg KOH / g, a primary hydroxyl group ratio of 89%, an acid value of 3 mg KOH / g and a Tg of 65°C.

[0121] The method of preparing the above high hiding black ink and its use in the injection of the film in the card are the same as in Example 1.

[0122] Example 3:

[0123] A high hiding black ink, substantially the same as Example 1, except that a different type of black pigment is used, i.e.

[0124] A high pigment carbon black having a mass fraction of 56 parts, a specific surface area of 260 m 2 / g, a primary particle size of 17 nm, an oil absorption value (DBP) of 170 mL / 100 g, a secondary particle size D 50 of 80 nm and a D 90 of 0.26 μm.

[0125] The method of preparing the above high hiding black ink and its use in the injection of the film in the card are the same as in Example 1.

[0126] Example 4:

[0127] A high hiding black ink, substantially the same as Example 1, except that the amount of high refractive index pigment is increased, i.e.

[0128] A rutile titanium dioxide having a mass fraction of 12 parts and a secondary particle size D 50 of 240 nm.

[0129] The method of preparing the above high hiding black ink and its use in the injection of the film in the card are the same as in Example 1.

[0130] Example 5:

[0131] A high hiding black ink, substantially the same as Example 1, except that a different type of polycarbonate polyol is used and the amount of curing agent is increased, i.e.

[0132] Polycarbonate diol, 15 parts by mass, molecular weight 2000, hydroxyl value 90 mg KOH / g;

[0133] Curing agent hexamethylene diisocyanate trimer, 22.5 parts by mass, isocyanate group content 21.8 wt%.

[0134] The preparation method of the high-hiding black ink and the application in the insert injection film piece are the same as those in Example 1.

[0135] Example 6:

[0136] A high-hiding black ink, which is basically the same as Example 1, except that the amount of hydroxyl acrylic resin is reduced, the amount of polycarbonate polyol is increased, and the amount of curing agent is reduced, i.e.

[0137] Hydroxyl acrylic resin (methyl methacrylate 50 wt%, cyclohexyl methacrylate 15 wt%, n-butyl acrylate 15 wt%, hydroxyethyl methacrylate 12 wt%, 1,1-dimethylol methacrylate 3 wt%, vinyl triethoxysilane 3 wt%, and isobutyryloxyethyl urea 2 wt%), 55 parts by mass, hydroxyl value 76 mg KOH / g, primary hydroxyl group proportion 100%, acid value 5 mg KOH / g, glass transition temperature 64°C;

[0138] Polycarbonate diol, 20 parts by mass, molecular weight 1500, hydroxyl value 56 mg KOH / g;

[0139] Curing agent hexamethylene diisocyanate trimer, 20 parts by mass, isocyanate group content 21.8 wt%.

[0140] The preparation method of the high-hiding black ink and the application in the insert injection film piece are the same as those in Example 1.

[0141] Example 7:

[0142] A high-hiding black ink, which is basically the same as Example 1, except that the amount of polycaprolactone polyol is reduced, and the amount of curing agent is reduced, i.e.

[0143] Polycaprolactone diol, 2 parts by mass, molecular weight 1000, hydroxyl value 113 mg KOH / g;

[0144] Curing agent hexamethylene diisocyanate trimer, 19.3 parts by mass, isocyanate group content 21.8 wt%.

[0145] Example 8:

[0146] A high hiding black ink, which is substantially the same as that of Example 1, except that the amount of polycaprolactone polyol is increased, and the amount of curing agent is also increased, i.e.

[0147] Polycaprolactone diol, 8 parts by mass, molecular weight 1000, hydroxyl value 113 mg KOH / g;

[0148] Curing agent hexamethylene diisocyanate trimer, 26 parts by mass, isocyanate group content 21.8 wt%.

[0149] The preparation method of the above high hiding black ink and the application thereof in the insert injection film are the same as those of Example 1.

[0150] Example 9:

[0151] A high hiding black ink, which is substantially the same as that of Example 1, except that the proportion of black pigment and high refractive index pigment is adjusted, i.e.

[0152] High pigment carbon black, 50 parts by mass, specific surface area 180 m 2 / g, primary particle size 25 nm, oil absorption value (DBP) 110 mL / 100 g, secondary particle size D 50 60 nm, D 90 0.14 μm;

[0153] Rutile titanium dioxide, 10 parts by mass, secondary particle size D 50 240 nm.

[0154] The preparation method of the above high hiding black ink and the application thereof in the insert injection film are the same as those of Example 1.

[0155] Example 10:

[0156] A high hiding black ink, which is substantially the same as that of Example 1, except that the types of hydroxyl acrylic resin and polycarbonate polyol are adjusted, and the amount of curing agent is also increased, i.e.

[0157] Hydroxyl acrylic resin (methyl methacrylate 40 wt%, isobornyl methacrylate 15 wt%, n-butyl acrylate 20 wt%, hydroxyethyl methacrylate 16.1 wt%, trimethylolpropane triacrylate 6.9 wt% and isobutyryloxyethyl urea 2 wt%), 60 parts by mass, hydroxyl value 108 mg KOH / g, primary hydroxyl group proportion 90%, acid value 4 mg KOH / g, glass transition temperature 50.7°C;

[0158] Polycarbonate diol, 15 parts by mass, molecular weight 1500, hydroxyl value 70 mg KOH / g;

[0159] Curing agent hexamethylene diisocyanate trimer, 27.8 parts by mass, isocyanate group content 21.8 wt%.

[0160] The preparation method of the high covering black ink and the application in the insert injection film piece are the same as example 1.

[0161] Comparative example 1:

[0162] A black ink, basically the same as example 1, the difference is that different types of hydroxy acrylic acid resin are replaced, and the amount of curing agent is increased, that is, the amount of curing agent is increased to 33.68 parts by mass, and the isocyanate group content is 21.8 wt%.

[0163] Hydroxy acrylic acid resin (methyl methacrylate 40 wt%, ethyl methacrylate 8 wt%, 2-ethylhexyl acrylate (2-EHA) 25 wt%, hydroxyethyl methacrylate 15.19 wt%, 1,1-dimethylol methacrylate 9.81 wt%, vinyl triethoxysilane 1 wt%, and isobutene acryloyl urea 1 wt%), 60 parts by mass, hydroxyl value 140 mg KOH / g, primary hydroxyl group ratio 100%, acid value 5 mg KOH / g, Tg 58℃;

[0164] Curing agent hexamethylene diisocyanate trimer, 33.68 parts by mass, isocyanate group content 21.8 wt%.

[0165] The preparation method of the high covering black ink and the application in the insert injection film piece are the same as example 1.

[0166] Comparative example 2:

[0167] A black ink, basically the same as example 1, the difference is that there is no high refractive index pigment in the formula, that is, the amount of curing agent is increased to 33.68 parts by mass, and the isocyanate group content is 21.8 wt%.

[0168] Rutile titanium dioxide, 0 parts by mass.

[0169] The preparation method of the high covering black ink and the application in the insert injection film piece are the same as example 1.

[0170] Comparative example 3:

[0171] A black ink, basically the same as example 1, the difference is that the amount of polycaprolactone polyol is increased, and the amount of curing agent is increased, that is, the amount of curing agent is increased to 33.68 parts by mass, and the isocyanate group content is 21.8 wt%.

[0172] Polycaprolactone diol, 20 parts by mass, molecular weight 1000, hydroxyl value 113 mg KOH / g;

[0173] Curing agent hexamethylene diisocyanate trimer, 24 parts by mass, isocyanate group content 21.8 wt%.

[0174] The preparation method of the high-hiding black ink and the application in the insert injection film are the same as those in Example 1.

[0175] The ink and the insert injection film are subjected to the following detection or test, and then the detection or test results are analyzed.

[0176] Test Example 1

[0177] The ink is subjected to a hot tensile rate test, and the specific steps are as follows:

[0178] The test standard refers to ASTM D638 (Plastic Tensile Property Test Method), which is suitable for thin film materials.

[0179] The ink is coated on a PET film with a thickness of 50 μm, and after curing, the ink layer is peeled off and cut into dumbbell-shaped samples with a gauge length of 25 mm x width of 5 mm;

[0180] The sample is preheated in an oven at 150°C for 5 min to eliminate thermal stress, immediately transferred to the tensile machine clamp, and stretched at a rate of 50 mm / min under constant temperature conditions until fracture.

[0181] The calculated hot tensile rate = (gauge length at fracture - original gauge length) / original gauge length x 100%.

[0182] Test Example 2

[0183] The insert injection film is subjected to a heat aging performance test, and the specific steps are as follows:

[0184] The insert injection film is cut into a 50 mm x 50 mm sample;

[0185] The equipment and conditions use an X-Rite Ci64 spectrophotometer with a D65 light source and an observation angle of 10° to measure the initial color difference;

[0186] The sample is hung in the center of a 105±2°C oven, avoiding contact with the oven wall;

[0187] Every 100 h, it is cooled to room temperature, and the color difference ΔE is calculated and measured according to the CIE Lab formula;

[0188] After 500 h, the final ΔE and the surface state of the coating, such as cracking and peeling, are recorded.

[0189] Test Example 3

[0190] The ink is subjected to a hiding performance test, and the specific steps are as follows:

[0191] The test standard refers to ISO 6504-3 (Determination of the hiding power of paints);

[0192] Equipment and condition Spectrophotometer and black and white contrast card in line with ISO 2814 standard;

[0193] The ink was coated on the black and white contrast card with a wet film thickness of 4 μm, and the reflectivity (Y value) of the black area (R 黑 ) and white area (R 白 ) was measured after curing;

[0194] The reflectivity (Y value) of the black area (R 黑 ) and white area (R 白 ) was measured respectively;

[0195] The calculated contrast ratio (hiding power) = R 黑 / R 白 x 100%;

[0196] The hiding power ≥ 95% is qualified, and ≥ 98% is excellent.

[0197] Test Example 4:

[0198] The color density (D max ) of the above-mentioned insert injection film was tested, and the specific steps were as follows:

[0199] The equipment and condition were X-Rite 530 color densitometer, and the light hole diameter was 3 mm;

[0200] After the instrument was calibrated, the insert injection film was attached to the white ceramic back plate;

[0201] The reflectance density value D max was measured, and the higher the light absorption rate, the larger the D max value;

[0202] The average value of 5 points was taken, and D max ≥ 2.5 was qualified, and ≥ 3.0 was excellent.

[0203] Test Example 5:

[0204] The above-mentioned insert injection film was subjected to xenon lamp aging performance test, and the specific steps were as follows:

[0205] The test standard referred to ASTM G155 (xenon lamp aging test);

[0206] The equipment and condition were Q-LAB Q-SUN Xe-3 xenon lamp aging box, the irradiation intensity was 0.55 W / m 2 @ 340 nm, the blackboard temperature was 65±3℃, the relative humidity was 50±5%, and the cycle mode was light 102 min / spraying 18 min;

[0207] The test period was 1000 h (or until obvious failure);

[0208] The evaluation index was color difference ΔE (same as the heat aging performance test).

[0209] Test Example 6:

[0210] The insert injection film was subjected to 95℃ / 95%RH high temperature and high humidity test, and the specific steps were as follows:

[0211] The test standard referred to ASTM D3359 (crosshatch method);

[0212] The equipment and conditions used ESPEC PL-3KPH constant temperature and humidity test chamber, temperature was 95±2℃, humidity was 95±3%RH, time was 96h;

[0213] The insert injection film was vertically hung in the constant temperature and humidity test chamber;

[0214] After testing, it was cooled to room temperature, and whether it was blistered and delaminated was observed;

[0215] The adhesion was tested.

[0216] Test Example 7:

[0217] The above ink was subjected to solvent resistance performance test, and the specific steps were as follows:

[0218] The test standard referred to ASTM D5402 (solvent wiping method);

[0219] The reagents and tools used 99.7% ethanol soaked cotton cloth and 500g weight;

[0220] The cotton cloth was wrapped around the weight, and the ink surface was wiped in one direction with a constant pressure of 1kg;

[0221] Every 10 passes, the coating wear was checked by visual and color density change;

[0222] The number of wipes when the coating completely fell off was recorded.

[0223] The main performance test results of the ink and insert injection film in the above examples 1 to 7 were shown in Table 1.

[0224] Table 1 Main performance test results of ink and insert injection film in examples 1 to 7

[0225]

[0226] The main performance test results of the ink and insert injection film in the above examples 8 to 10 and comparative examples 1 to 3 were shown in Table 2.

[0227] Table 2 Main performance test results of ink and insert injection film in examples 8 to 10 and comparative examples 1 to 3

[0228] Test performance Example 8 Example 9 Example 10 Comparative Example 1 Comparative Example 2 Comparative Example 3 Heat stretch (150°C, %) 341 289 236 180 303 390 Heat aging color difference (ΔΕ) 0.6 0.7 0.8 0.8 0.3 5.5 Hiding power Excellent Excellent Excellent Excellent Pass Excellent Color density Excellent Excellent Excellent Excellent Pass Excellent Xenon light aging color difference (ΔΕ) 0.4 0.5 0.6 1.1 0.6 3.3 High temperature high humidity adhesion 0 rank 0 rank 0 rank 1 rank 0 rank 3 rank Solvent wiping resistance times >200 >200 >200 >200 >200 >200

[0229] As shown in Table 1 and Table 2, all the examples have good heat stretchability, heat aging, hiding power, light aging and high temperature and high humidity adhesion;

[0230] Compared with Examples 1 and 10, the too high hydroxyl value of the hydroxy acrylic resin in Comparative Example 1 leads to the increase of crosslinking density, so that the paint film becomes brittle, affecting the heat stretching result;

[0231] Compared with Example 1, the hiding power decreases in Comparative Example 2 without adding high refractive index pigment under the same amount of black pigment.

[0232] Compared with Example 1, the too large amount of polycaprolactone polyol in Comparative Example 3 brings negative effects on heat aging, light aging and high temperature and high humidity adhesion.

[0233] Based on the formula of the high-hiding black ink in the application, the synergistic effect of black pigment and high refractive index pigment is achieved to realize excellent hiding performance. By optimizing the hydroxy acrylic resin, polycarbonate polyol and polycaprolactone polyol, the heat stretching rate is more than 200%, which has excellent formability and heat aging and light aging performance, and meets the performance requirements when used as an automotive interior film in the embedded sheet injection molding process.

[0234] The above description of the examples is for the purpose of facilitating the understanding and use of the application by those skilled in the art. Those skilled in the art can easily make various modifications to these examples, and apply the general principles described herein to other examples without creative labor. Therefore, the application is not limited to the above examples, and the improvements and modifications made by those skilled in the art without departing from the scope of the application should be within the scope of protection of the application.

Claims

1. A high hiding black ink, characterized in that: The ink comprises the following components in parts by weight: 40-70 parts of hydroxy acrylic resin, 10-30 parts of polycarbonate polyol, 1-10 parts of polycaprolactone polyol, 40-70 parts of black pigment, 2-15 parts of high refractive index pigment, 15-40 parts of curing agent and 15-45 parts of dispersant.

2. A high hiding black ink according to claim 1, characterized in that: The hydroxy acrylic resin has a hydroxy value of 20 to 130 mg KOH / g, a primary hydroxyl ratio of not less than 60%, an acid value of 1 to 15 mg KOH / g, and a glass transition temperature of 40 to 90° C. The polycarbonate polyol has a molecular weight of 500 to 5000 and a hydroxyl value of 30 to 200 mg KOH / g; The molecular weight of the polycaprolactone polyol is 600-2000, and the hydroxyl value is 50-300 mg KOH / g.

3. A high hiding black ink according to claim 1, characterized in that: The black pigment is selected from one or more of carbon black, aniline black, titanium black, iron oxide black, and perylene black. The specific surface area of ​​the black pigment is 120 to 400 m 2 / g, primary particle size is 5-60nm, oil absorption value is 80-240mL / 100g, secondary particle size D 50 10~100nm, D 90 0.06~0.5μm; The high refractive index pigment is selected from one or more of magnetite, rutile titanium dioxide, anatase titanium dioxide, zirconium oxide, cerium oxide, zinc oxide, aluminum nitride, tungsten oxide, and aluminum oxide. The secondary particle size D of the high refractive index pigment 50 It is 150~400nm.

4. A high hiding black ink according to claim 1, characterized in that: The curing agent is selected from one or more of aromatic isocyanates, aliphatic isocyanates, and alicyclic isocyanates, or trimers or polymers thereof. The aromatic isocyanate is selected from one or more of toluene-2,4-diisocyanate, 4,4'-diphenylmethane diisocyanate, m-tetramethylxylene diisocyanate, naphthalene-1,5-diisocyanate, and p-phenylene diisocyanate. The aliphatic isocyanate is selected from one or more of hexamethylene diisocyanate, lysine diisocyanate, and trimethylhexamethylene diisocyanate. The alicyclic isocyanate is selected from one or more of dicyclohexylmethane-4,4'-diisocyanate and isophorone diisocyanate.

5. The high hiding black ink according to claim 1, characterized in that: The ink further comprises 0.3 to 1.5 wt% of a silane coupling agent relative to the solid mass.

6. A high hiding black ink according to claim 1, characterized in that: The ink further comprises 150 to 300 wt% of a solvent relative to the solid mass, wherein the solvent is selected from one or more of toluene, ethyl acetate, butanone, butyl acetate, N,N-dimethylformamide, propylene glycol methyl ether acetate, methyl ethyl ketone, and isophorone; The ink further comprises a catalyst in an amount of 0.1 to 0.5 wt% relative to the solid mass, wherein the catalyst is selected from one or more of tetramethylbutylene diamine, triethylenediamine, stannous octoate, dibutyltin dilaurate, lead octoate, cobalt octoate, iron octoate, zinc naphthenate, and tetraisobutyl titanate; The ink further comprises 0.5 to 2.5 wt% of a light absorber relative to the solid mass; The ink further comprises 0.5 to 2.5 wt% of a light stabilizer relative to the solid mass; The ink further comprises 0.05 to 0.3 wt% of a leveling agent relative to the solid mass; The ink further comprises 0.05 to 0.3 wt % of a defoaming agent relative to the solid mass.

7. A method for preparing a high hiding black ink according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: S1.

1. Mix part of the resin and dispersant with the black pigment and pre-disperse by sand milling to obtain a black pigment dispersion system; S1.

2. Mix the remaining resin and dispersant with the high refractive index pigment and pre-disperse by sand milling to obtain a high refractive index pigment dispersion system; S1.

3. Mix the two pigment dispersion systems and add a curing agent to obtain a mixed system; S1.

4. Add a silane coupling agent, a catalyst, a light absorber, a light stabilizer, a leveling agent, and a defoaming agent to the mixed system, and add a solvent to obtain a high-hiding black ink.

8. The method for preparing a high hiding black ink according to claim 7, wherein: In step S1.1, the addition ratio of the resin and the dispersant is 60-90 wt %; The input energy of sand milling in steps S1.1 and S1.2 is 55-100 kJ / kg; In step S1.3, a curing agent is added so that the molar ratio of the isocyanate group of the curing agent to the hydroxyl group of the resin is (1.05-1.1):1; In step S1.4, a solvent is added to adjust the viscosity of the ink to 2000-4000 cP.

9. Use of the high hiding black ink according to any one of claims 1 to 6 in an insert injection molded film, characterized in that: The insert injection molded film comprises a protective layer (2), an ink layer (3), an adhesive layer (4) and a substrate layer (5) in sequence. The preparation method of the insert injection molded film comprises the following steps: S2.1, gravure coating a high-hiding black ink on the carrier film (1) coated with the protective layer (2) to form an ink layer (3); S2.2, coating an adhesive on the ink layer (3) to form an adhesive layer (4), and curing the adhesive layer to obtain a thermal transfer film; S2.

3. The thermal transfer film and the substrate layer (5) are heat-pressed together, wherein the adhesive layer (4) of the thermal transfer film is in contact with the substrate layer (5), the carrier film (1) is peeled off, and the protective layer (2) and the ink layer (3) are bonded to the surface of the substrate layer (5) under the action of the adhesive layer (4), forming an embedded injection-molded film with high-hiding black ink.

10. The use of a high hiding black ink according to claim 9, characterized in that: The thickness of the ink layer (3) in step S2.1 is 1 to 10 μm.

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