An ultra-dull composite transfer film, an insulating film prepared by using the same and a preparation method thereof

Abstract

The application discloses a kind of super-matt composite transfer printing films, the INS film piece and preparation method prepared by using it, the super-matt composite transfer printing film includes sequentially stacked carrier film, micro-texture mold layer, hardening layer, pattern layer and adhesive layer.Micro-texture mold layer includes elastic resin, acrylic resin, cellulose acetate butyrate resin, low surface energy resin, inorganic filler and organic filler, forming a release interface on the surface layer, with texture construction and release function;Hardening layer is a transparent protective layer.After composite transfer printing and stripping carrier film and micro-texture mold layer, the hardening layer is located at the outermost and retains the mirror negative appearance of mold layer surface texture, and the 60° gloss is not higher than 5GU.The application realizes the unity of super-matt appearance and excellent hand feeling by decoupling the functions of micro-texture mold layer and hardening layer, while taking into account the surface protection performance and thermoforming adaptability, overcoming the contradiction that super-matt appearance, surface protection and formability are difficult to consider in the prior art.

Description

Technical Field

[0001] This invention belongs to the technical field of functional transfer films and in-mold decorative films, specifically relating to an ultra-matte composite transfer film, an ultra-matte INS film prepared using the ultra-matte composite transfer film, and a preparation method thereof. Background Technology

[0002] In-film decoration and insert molding (INS) technology has been widely used in the surface manufacturing of automotive interior parts. The basic process involves shaping and trimming a film with a decorative or functional layer, placing it into a mold, and then injection molding molten resin onto the back side to bond the decorative or functional layer to the surface of the part. Coating films used on automotive interior surfaces, in addition to providing surface protection, must also consider formability, chemical resistance, and compatibility with insert molding.

[0003] Currently, the technical approaches to achieving ultra-matte or soft-feel surfaces are mainly divided into two categories.

[0004] The first category involves a matte finish route using internal fillers in the terminal surface layer. This involves adding inorganic matting powders, organic microspheres, wax-based or silicone-based additives to the surface resin to create a low-gloss and tactile effect. For example, WO2016039546A1 discloses a method of forming a matte surface by combining inorganic particles with matting components; CN103627306A discloses a method of creating a matte and tactile feel using matting powders and velvet powders; and CN114539890A discloses a method of constructing a velvety coating layer using modified polyester resin, modified siloxane, and polyurethane microsphere powder. A common characteristic of this type of route is that the low gloss and tactile feel primarily rely on the filler system within the surface layer.

[0005] The second category is the gloss control route via texture transfer. For example, US20110117292A1 discloses a method of transferring texture to the coating surface using a textured polymer film when the coating is in a partially cured state, thereby obtaining the desired gloss and appearance. This route demonstrates that gloss control can also be achieved through surface morphology control rather than solely relying on bulk fillers.

[0006] However, existing surface structures for INS films still present technical challenges: the final hardened layer must provide hardness, scratch resistance, and chemical resistance, while also adapting to subsequent thermoforming and in-mold injection molding processes. For example, CN105765002A points out that if the crosslinking density of the hard coating used for molding is too high, although the surface properties are good, it is prone to cracking during three-dimensional processing. Therefore, if the final hardened layer simultaneously undertakes the three main functions of matte finish, tactile feel, and protection, its system design often requires a compromise between low gloss, surface protection, and molding compatibility.

[0007] In addition, automotive interior surfaces are exposed to sunscreen, hand cream, sweat, and other everyday chemicals during actual use, which can cause changes in appearance and feel. Summary of the Invention

[0008] In response to one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides an ultra-matte composite transfer film, an INS film prepared using the film, and a preparation method thereof. Through the functional decoupling design of the micro-textured mold layer and the hardening layer, it achieves both ultra-matte gloss (60° gloss ≤ 5 GU) and a delicate touch.

[0009] To achieve the above objectives, according to a first aspect of the present invention, an ultra-matte composite transfer film is provided, comprising a carrier film, a micro-texture mold layer, a hardening layer, a pattern layer, and an adhesive layer stacked sequentially: Based on solid content, the raw materials of the microtextured mold layer include 35-70 wt% elastic resin, 15-40 wt% acrylic resin, 1-10 wt% cellulose acetate butyrate resin, 3-8 wt% low surface energy resin, 1-15 wt% inorganic filler and 0.5-5 wt% organic filler. The raw material of the microtextured mold layer also includes a crosslinking agent, and the amount of the crosslinking agent is calculated based on the equivalent ratio of NCO groups to OH groups in the system of 1.02 to 1.10; The surface of the micro-textured mold layer facing the hardened layer has micro-textures, and the micro-textured mold layer also has a release function. The hardened layer is a protective layer, and its surface facing the microtextured mold layer has a mirror negative microtexture, and the gloss of the surface at 60° is not higher than 5 GU.

[0010] As a further improvement of the present invention, the elastic resin includes one or more of polyester polyol, polyether polyol, polycaprolactone polyol, polycarbonate diol, and polycarbonate-modified polyester polyol. Preferably, the elastic resin is polycarbonate diol with a number average molecular weight of 800-2000 and a hydroxyl value controlled at 55-140 mg KOH / g.

[0011] As a further improvement of the present invention, the acrylic resin is a hydroxyl acrylic resin, wherein the number-average molecular weight of the acrylic resin is 3000–15000, the Tg is 15–60°C, the hydroxyl value is 60–130 mg KOH / g, and the acid value is 1–10 mg KOH / g; and / or, The cellulose acetate butyrate resin has a butyryl content of 45–55 wt%, a hydroxyl content of 1.0–2.5 wt%, and an ASTM-A viscosity of no more than 3 seconds.

[0012] As a further improvement of the present invention, the low surface energy resin includes one or more of organosilicon resin, silicon-modified acrylic resin, fluoropolymer, and silicon- or fluorine-containing block copolymer; preferably, the organosilicon resin is a polydimethylsiloxane with primary hydroxyl end capping.

[0013] As a further improvement of the present invention, the inorganic filler includes one or more of precipitated silica, thermal silica, and surface-treated precipitated silica; preferably, the median particle size D50 of the inorganic filler is 1 to 12 μm, and the D90 is not greater than 20 μm. The organic filler includes one or more of thermosetting urea-based micropowder, polyurethane microspheres, and cross-linked acrylic microspheres; preferably, the median particle size D50 of the organic filler is 1 to 12 μm.

[0014] As a further improvement of the present invention, the raw material of the microtextured mold layer also includes a solvent, which includes one or more of esters, ketones and aromatic hydrocarbons; the total solid content of the raw material of the microtextured mold layer is 25 to 45 wt%.

[0015] As a further improvement of the present invention, the hardening layer comprises 60-80 wt% hydroxyl acrylic resin and 20-40 wt% polycarbonate diol; the hardening layer further comprises a crosslinking agent, the amount of which is based on an NCO:OH equivalent ratio of 0.98-1.08; and / or, The raw materials of the patterned layer, on a solid basis, include 40-80 wt% polyurethane resin, 20-60 wt% ethylene copolymer resin or acrylic resin.

[0016] According to a second aspect of the present invention, a method for preparing an ultra-dull INS film is provided, using the aforementioned ultra-dull composite transfer film, comprising the following steps: (1) A microtextured mold layer is coated on the surface of the carrier film, and the microtextured mold layer is dried and cured in stages at 40-65℃, 70-95℃ and 100-130℃ in sequence; (2) A hardening layer is applied to the surface of the microtextured mold layer, wherein the hardening layer is a transparent protective layer; (3) Print a pattern layer on the side of the hardened layer opposite to the microtextured mold layer; (4) Apply an adhesive layer to the side of the pattern layer opposite to the hardened layer; (5) The multilayer structure obtained in step (4) is hot-pressed and composite transferred with the substrate layer, and the carrier film and the micro-texture mold layer are peeled off during the composite transfer process, so that the hardened layer, the pattern layer and the adhesive layer are retained on the substrate surface, wherein the hardened layer is located on the outermost side, and the ultra-dull INS film is obtained.

[0017] As a further improvement of the present invention, in step (5), the composite transfer temperature is 150-200℃, the composite pressure is 0.2-0.6MPa, and the composite linear speed is 1-8m / min.

[0018] According to a third aspect of the present invention, an ultra-matte INS film is provided, which is formed by transfer using the ultra-matte composite transfer film, or by preparation using the preparation method described above, comprising a substrate layer, an adhesive layer, a pattern layer and a hardening layer stacked sequentially; wherein the gloss of the outer surface of the hardening layer at 60° is not higher than 5 GU.

[0019] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art: (1) This invention constructs a multi-scale composite surface structure combining a micron-level main scattering framework and submicron-level fine textures through the synergistic effect of the components in the microtextured mold layer. Inorganic fillers construct the micron-level main scattering framework, elastic resin provides continuous phase flexibility, acrylic resin provides rapid surface freezing capability, CAB resin inhibits wet film backflow and passivates particle edges, low surface energy resin provides release function while promoting the generation of submicron-level fine textures, and organic fillers modify the tactile feel. Under the synergistic effect of the above components, a stable, controllable, and reproducible multi-scale microtextured surface is spontaneously formed.

[0020] After replication through the hardened layer, the resulting film surface has a gloss level of no more than 5 GU at 60°, making it particularly suitable for applications with high anti-glare requirements, such as automotive interiors. Simultaneously, the submicron-level fine undulations formed by phase separation in a multi-resin system, combined with the passivation modification of the skeleton peaks by organic fillers, transform the surface from the rough, sandy feel of traditional matte finishes to a delicate touch, achieving both an ultra-matte appearance and excellent tactile feel.

[0021] (2) This invention endows the micro-textured mold layer with the function of creating an ultra-matte appearance and the hardened layer with the function of surface protection. The two have a clear division of labor and decoupled functions. The hardened layer does not need to add a high content of matte particles, maintains a pure and continuous polyurethane network structure, has higher density and fewer structural defects, and thus exhibits excellent resistance to chemical media such as hand cream, sunscreen, artificial sweat and alcohol.

[0022] (3) In this invention, a single-ended dihydroxyl-terminated polydimethylsiloxane is introduced as a low surface energy resin in the microtextured mold layer. During the drying and curing process, it spontaneously accumulates on the surface and forms a low surface energy release interface, eliminating the need for a separate release layer. This integrated design reduces the number of interlayer interfaces, avoids interference from heterogeneous interface slippage on texture replication, improves the fidelity of the hardened layer in replicating the surface morphology of the mold layer, and simplifies the structure and preparation process of the composite transfer film.

[0023] (4) The microtextured mold layer of the present invention adopts a segmented drying process. In the first stage, the elastic resin ensures the uniform spreading of the wet film; in the second stage, the system enters the phase separation window, the acrylic resin and CAB resin achieve rapid surface freezing, the inorganic filler completes the construction of the main skeleton, and the low surface energy resin migrates to establish the release interface; in the third stage, the crosslinking reaction fixes the phase separation structure, and the organic filler passivates the skeleton peaks. Through the synergy of process and formulation, a stable and controllable multi-scale textured surface is obtained. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the interlayer structure of the ultra-dull composite transfer film before transfer, according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the interlayer structure of the ultra-dull composite transfer film after transfer according to an embodiment of the present invention.

[0025] In all the accompanying drawings, the same reference numerals denote the same technical features, specifically: 1, carrier film; 2, microtextured mold layer; 3, hardening layer; 4, pattern layer; 5, adhesive layer; 6, substrate layer. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0028] like Figure 1 As shown, the present invention provides an ultra-matte composite transfer film, comprising a carrier film 1, a micro-texture mold layer 2, a hardening layer 3, a pattern layer 4, and an adhesive layer 5 stacked sequentially.

[0029] The microtexture mold layer 2 is disposed on the surface of the carrier film 1 (such as a PET carrier film) to construct a reproducible microtexture surface in a planar state, and to complete interface shaping and subsequent transfer when combined with the hardening layer.

[0030] The hardening layer 3 is disposed on the surface of the microtexture mold layer 2 to replicate the mirror negative morphology of the surface of the microtexture mold layer 2 and to serve as a transparent protective layer on the outermost surface in the final film. The pattern layer 4 is disposed on the side of the hardened layer 3 opposite to the microtexture mold layer 2, and is used to form decorative patterns, masking layers or light-transmitting windows; The adhesive layer 5 is disposed on the side of the pattern layer 4 away from the hardening layer 3, and is used to transfer the hardening layer 3 and the pattern layer 4 to the surface of the substrate layer 6 (such as ABS or ABS / PC).

[0031] In a preferred embodiment, the raw materials of the microtextured mold layer 2, based on solid content, include 35-70 wt% elastic resin, 15-40 wt% acrylic resin, 1-10 wt% cellulose acetate butyrate resin (CAB resin), 3-8 wt% low surface energy resin, 1-15 wt% inorganic filler and 0.5-5 wt% organic filler.

[0032] In this embodiment, the microtextured mold layer 2 adopts a reactive solvent system, in which elastic resin serves as the main body to form a continuous phase, providing basic mechanical properties and spreadability for the coating; acrylic resin and cellulose acetate butyrate resin (CAB resin) work together to regulate film strength, surface freezing speed and local compatibility; low surface energy resin is used to establish a surface enrichment interface and provide release function; inorganic filler is used to construct a micron-level main texture skeleton; organic filler is used to modify surface friction characteristics and improve the tactile smoothness.

[0033] Based on the above component design, a multi-material system composed of inorganic fillers, elastic resin, acrylic resin, and CAB resin spontaneously forms multi-scale microtextures during coating and curing. Among them, the inorganic fillers form a micron-scale master scattering framework in the continuous resin phase; the elastic resin, acrylic resin, and CAB resin undergo micro-phase separation due to limited compatibility, generating submicron-scale fine textures in situ on the surface and gaps of the master framework.

[0034] Thus, a multi-scale composite structure is constructed on the surface of the microtextured mold layer 2, in which a micron-scale skeleton and submicron-scale fine textures are nested. This structure is entirely determined by the inherent properties of the material system itself, without the need for external templates or post-processing. The micron-scale skeleton, acting as the main scattering unit, significantly reduces specular reflection, while the submicron-scale fine textures further disperse residual reflected light and eliminate local bright spots. Together, they achieve ultra-low gloss and a delicate feel.

[0035] Furthermore, the raw material of the microtextured mold layer 2 also contains a crosslinking agent, preferably a two-component polyurethane curing system. Besides forming a crosslinking network, the crosslinking agent also promotes microscopic phase separation in the resin system due to limited compatibility: as the crosslinking reaction proceeds, the molecular weight increases rapidly, compatibility differences are amplified, and phase separation is further intensified, ultimately forming fine textures between the main framework. Simultaneously, the crosslinking network fixes the already formed phase-separated structure.

[0036] Preferably, the crosslinking agent is an aliphatic polyisocyanate, and more preferably an HDI-type aliphatic polyisocyanate trimer, which has high functionality and can form a continuous network at a low addition amount.

[0037] Preferably, the NCO content of the crosslinking agent is 18–23 wt%, and the functionality is preferably 3.0–3.6. In the microtextured mold layer 2 system, the amount of crosslinking agent is calculated based on the equivalent ratio of NCO groups to OH groups in the system of 1.02–1.10, preferably 1.04–1.08. When the NCO:OH ratio is too low, network growth is insufficient, the surface layer freezes slowly, and the texture is more easily re-wetted during the subsequent hardening layer construction; when the ratio is too high, crosslinking is too fast, local shrinkage increases, the edges of the microtexture become sharp, and coarse phase separation is easily induced.

[0038] Furthermore, the elastic resin includes, but is not limited to, polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate diols, and polycarbonate-modified polyester diols, preferably polycarbonate diols. The main chain of polycarbonate diols consists of repeating carbonate units with hydroxyl groups at the chain ends, allowing it to react with crosslinking agents (polyisocyanates) to form a polyurethane network and maintain sufficient fluidity in the early stages of drying. This characteristic enables it to function as both a continuous and compliant phase in the mold layer: ensuring uniform spreading and filler coating in the early stages of coating, providing a flexible background for particle skeletons and phase separation in the middle and later stages of drying, and providing good interfacial adhesion when in contact with the hardened layer. Simultaneously, its limited compatibility with acrylic resins and CAB resins causes fine-scale phase separation due to changes in solubility parameters during solvent evaporation, which is then fixed into a heterogeneous micro-textured surface by the crosslinking reaction.

[0039] Preferably, the number-average molecular weight of the elastic resin is 800–2000, more preferably 1000–1500; the corresponding hydroxyl value is controlled at 55–140 mg KOH / g, more preferably 70–115 mg KOH / g. When the molecular weight is too low, the chain segments are too short, resulting in increased shrinkage after crosslinking, sharper surface peaks, and a tendency for the main texture to turn into a sandy surface; when the molecular weight is too high, the system viscosity increases, surface freezing is delayed, and the fine texture between the skeletons is not easily fixed.

[0040] In a preferred embodiment, the acrylic resin is a hydroxy acrylic resin, which can be a commercially available product, such as DOMACRYL 5210 75 BAc, DOMACRYL 5481 75 BAc, or DOMACRYL 5485 75 BAc / MAK. The hydroxy acrylic resin is formed by copolymerization of hydroxyl-functional monomers, hard monomers, soft monomers, and a small amount of acidic monomers. This copolymer structure gives the acrylic resin transparency, reactive hydroxyl groups, moderate polarity, and a high Tg. The hydroxyl-functional monomers are selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; the hard monomers are selected from one or more of methyl methacrylate, isoborneol methacrylate, and styrene; the soft monomers are selected from one or more of butyl acrylate, butyl methacrylate, and isooctyl acrylate; and the acidic monomers are selected from one or more of acrylic acid and methacrylic acid. In practice, those skilled in the art can choose commercially available products or prepare them using known methods as needed.

[0041] Acrylic resin functions as both a surface-freezing phase and a rigid co-film phase in the mold layer. Its high Tg allows the system to establish surface viscoelasticity more quickly in the later stages of drying, inhibiting continuous leveling of the wet film and thus preserving the micro-undulations formed by filler and phase separation. At the same time, the participation of hydroxyl groups in the crosslinking reaction increases the surface strength, making the established main and fine textures less prone to rewetting or disturbance during subsequent hardening layer construction. Furthermore, the polarity and segmental differences between acrylic resin and polycarbonate diol and CAB resin provide a thermodynamic basis for microphase separation.

[0042] Preferably, the number-average molecular weight of the acrylic resin is 3000–15000, more preferably 4000–10000; the Tg is 15–60℃, more preferably 25–50℃; the hydroxyl value is 60–130 mg KOH / g, more preferably 70–110 mg KOH / g; and the acid value is 1–10 mg KOH / g, more preferably 2–6 mg KOH / g. When the molecular weight is below 3000, the surface cohesion is insufficient; when it is above 15000, the application viscosity increases too quickly, which is not conducive to microgravure coating. When the Tg is below 15℃, the surface freezing ability is insufficient; when it is above 60℃, the modulus difference with the main elastic resin is too large, local shrinkage stress increases, and it is easier to induce coarse phase separation rather than fine-scale phase separation. Controlling the hydroxyl and acid values ​​within the above ranges ensures both crosslinking efficiency and filler wetting, while preventing the system from becoming an overly homogeneous single-phase state due to excessively high polarity.

[0043] In a preferred embodiment, the CAB resin has a cellulose backbone with side groups including acetyl, butyryl, and residual hydroxyl groups. The high chain rigidity of the cellulose backbone significantly improves the viscoelasticity of the wet film surface; the acetyl groups provide a certain degree of hardness and solubility; the butyryl groups expand the compatibility window with elastic and acrylic resins and reduce water absorption; and the residual hydroxyl groups impart limited reactivity.

[0044] The CAB resin is further preferably cellulose acetate butyrate with high butyryl content, low hydroxyl content, and low viscosity grade. The butyryl content of the CAB resin is 45–55 wt%, preferably 50–53 wt%; the hydroxyl content is 1.0–2.5 wt%, preferably 1.5–2.0 wt%; and the ASTM-A viscosity of the CAB resin is controlled at 0.01–3 s, preferably 0.05–2 s. The high butyryl structure helps to adjust the compatibility between the CAB and the host resin to a suitable limited compatibility range and reduces the tendency for thermal reflow; the low hydroxyl level allows it to be grafted into the polyurethane network in a limited manner without excessively occupying the isocyanate equivalent; and the low viscosity grade reduces the increase in application viscosity.

[0045] In this invention, CAB resin plays a surface freezing regulation role. After adding CAB, the surface viscosity and viscoelasticity rise rate of the wet film in the later stage of solvent evaporation are significantly improved, shortening the liquid phase rearrangement time around the skeleton, thus making the peak-valley structure formed by inorganic fillers less susceptible to being smoothed by continuous reflow. At the same time, the limited compatibility between CAB and polycarbonate glycol and acrylic resin can transform sharp particle edges into gentle, fine-scale undulations, changing the low-gloss surface from coarse-matte to fine-matte.

[0046] Further, the low surface energy resin includes one or more of organosilicon resins, silicone-modified acrylic resins, fluoropolymers, and silicone / fluorine-containing block copolymers. Organosilicon resins, in particular, possess both low surface energy and high chain flexibility, making them more prone to enrichment at the air interface during solvent evaporation. Therefore, organosilicon resin systems are further preferred for low surface energy. More preferably, the organosilicon resin is a reactive organosilicon resin, especially methanol-terminated polydimethylsiloxane (PDMS) with a single primary hydroxyl group. The hydroxyl groups of this methanol-terminated PDMS are connected to the siloxane backbone via carbon chains, enabling it to participate in the crosslinking reactions of polyurethane, polyester, and epoxy systems.

[0047] Preferably, the number average molecular weight of the low surface energy resin is 1000-5000, and more preferably 1500-3500.

[0048] In this invention, the low surface energy resin can enrich the surface layer and reduce the surface energy, forming a release interface that does not depend on an independent release layer; and it forms a more obvious compositional gradient with the host resin near the surface layer, promoting the generation of finer submicron-level textures between the main skeletons; at the same time, it can suppress excessive mirroring, so that the low gloss structure remains stable when it is replicated to the hardened layer.

[0049] In a preferred embodiment, the inorganic filler includes one or more of precipitated silica, thermal silica, and surface-treated precipitated silica, and more preferably, surface-treated precipitated silica.

[0050] Inorganic fillers, acting as the primary scattering framework for low-gloss surfaces, are dispersed within the continuous resin phase, forming micron-sized peaks and valleys on the coating surface. While these particle protrusions alone can achieve a low-gloss finish, the surface often feels rough, similar to sandpaper. When the particle framework coexists with the phase-separated structure within the resin system due to limited compatibility, finer secondary undulations form between the particles. This multi-scale structure further weakens specular reflection, transforming the surface from a coarse-matte (low-gloss but rough) to a fine-matte (low-gloss and smooth) finish.

[0051] More preferably, the median particle size D50 of the inorganic filler is 1–12 μm, more preferably 2–8 μm; D90 is preferably no greater than 20 μm. When D50 is too low, the particles are more easily buried by resin, resulting in insufficient main skeleton; when D50 is too high, the peaks and valleys are too deep, and the surface is prone to uneven brightness and increased roughness.

[0052] In a preferred embodiment, the organic filler includes one or more of thermosetting urea-based micropowder, polyurethane microspheres, and cross-linked acrylic microspheres. More preferably, the apparent particle size D50 of the organic filler is 1–12 μm, more preferably 2–9 μm.

[0053] Organic fillers are mainly distributed near the peaks of the inorganic framework and in the inter-framework region, passivating the peaks of the main framework and reducing local frictional abrupt changes and gloss flash points, resulting in a more uniform and delicate low-gloss appearance on the final surface. When the content of organic fillers is too low, the tactile modification effect is insufficient; when the content is too high, it will weaken the boundary clarity of the main framework, leading to a decrease in texture replication accuracy.

[0054] More preferably, the microtextured mold layer 2 may include one or more of the following: dispersant, wetting agent, defoamer, catalyst, and anti-settling agent, as needed. The dispersant stabilizes the interface between inorganic and organic fillers; the wetting agent improves the spreading of the base film surface and filler coating; the defoamer inhibits bubble entrapment during the microgravity reverse coating process; and the catalyst regulates the reaction rate between hydroxyl groups and the crosslinking agent. The introduction of these additives not only improves workability but, more importantly, prevents defects such as pinholes, bubbles, flocculation, and sedimentation from disrupting the uniformity of the multi-scale texture, thereby avoiding deterioration of gloss and appearance.

[0055] Preferably, the dosage ranges of various additives are as follows: dispersant 0.2-1.5 wt%, wetting agent 0.05-0.30 wt%, defoamer 0.05-0.30 wt%, and catalyst 0.01-0.20 wt%.

[0056] In a preferred embodiment, the solvent in the microtextured mold layer 2 includes one or more of esters, ketones, and aromatic hydrocarbon solvents. Preferably, a compound system of esters, ketones, and aromatic hydrocarbon solvents is used, with ester solvents accounting for 35–60 wt%, ketone solvents accounting for 15–35 wt%, and slow-volatile components accounting for 10–30 wt%. The ester solvents provide the bulk solubility and maintain a stable open time, the ketone solvents improve the solubility of CAB and acrylic resins and provide a faster evaporation rate, and the aromatic hydrocarbons or high-boiling-point ketone solvents are used to prolong the liquid-phase rearrangement time.

[0057] More preferably, the total solids content of the coating in the microtextured mold layer 2 is controlled at 25–45 wt%, preferably 30–40 wt%; the application viscosity is controlled at 20–120 mPa·s at the coating temperature, preferably 30–80 mPa·s. These parameter ranges ensure that the microgravure coating can stabilize liquid transfer while allowing sufficient time for resin phase separation and surface enrichment, thereby forming the composite surface required for low gloss.

[0058] In the microtextured mold layer 2 of this invention, the main elastic resin ensures coating spread and filler encapsulation, and provides a flexible background for subsequent structure formation; inorganic fillers construct a micron-level main scattering framework to achieve primary matting; acrylic resin and CAB resin jointly regulate the rheological behavior and surface freezing rate of the system. The high glass transition temperature of acrylic resin enables the wet film surface to quickly establish viscoelasticity, while CAB resin further enhances surface viscoelasticity and inhibits backflow. Their synergistic effect ensures that the formed micro-undulations are not smoothed out during the later stages of drying; low surface energy resin accumulates on the surface, forming a release interface and promoting fine-scale phase separation, generating submicron-level fine textures; organic fillers passivate the framework peaks, improving the tactile smoothness. The synergistic effect of these components results in a composite structure of micron-level main scattering and submicron-level diffuse reflection on the mold layer surface. After replication by the hardened layer, an ultra-matte appearance and delicate feel with a gloss level ≤5 GU (60°) can be achieved without adding matting particles.

[0059] Furthermore, a hardened layer 3 is disposed on the surface of the microtextured mold layer 2, and after the composite transfer and peeling off of the carrier film 1 and the microtextured mold layer 2, it is located on the outermost surface of the resulting ultra-matte INS film. This hardened layer 3 is used to replicate the mirror negative morphology of the surface of the microtextured mold layer 2 and exists as a transparent protective layer in the final film. In addition to providing scratch resistance, abrasion resistance, chemical resistance, heat aging resistance, and appearance retention properties, the hardened layer 3 also needs to adapt to the synchronous deformation during subsequent thermoforming and back injection molding processes to avoid brittleness, whitening, loss of gloss, or texture distortion during heating, stretching, and forming.

[0060] Preferably, the hardened layer 3 employs a thermosetting polyurethane system, comprising hydroxyl acrylic resin, polycarbonate diol, and aliphatic polyisocyanate (crosslinking agent). The hydroxyl acrylic resin provides surface hardness, transparency, scratch resistance, and chemical resistance; the polycarbonate diol adjusts flexibility and improves strain tolerance during thermoforming; and the aliphatic polyisocyanate forms a transparent, continuous, and densely crosslinked polyurethane network. Through this resin system design, the hardened layer maintains high transparency and surface protection while also ensuring moldability during subsequent processing.

[0061] Preferably, the hydroxyl acrylic resin comprises one or more copolymers of hydroxyethyl acrylate, hydroxypropyl acrylate, methyl methacrylate, butyl methacrylate, butyl acrylate, and styrene; the polycarbonate diol is preferably an aliphatic linear polycarbonate diol. The aliphatic polyisocyanate is preferably an HDI-type aliphatic polyisocyanate trimer or an isocyanurate-type polyisocyanate.

[0062] Preferably, based on the solids content of the hardened layer 3, the amount of hydroxyl acrylic resin is preferably 60-80 wt%, more preferably 65-75 wt%; the amount of polycarbonate diol is preferably 20-40 wt%, more preferably 25-35 wt%. The amount of crosslinking agent is based on an NCO:OH equivalent ratio of 0.98-1.08, which is beneficial for the hardened layer 3 to retain the necessary flexibility while achieving a high crosslinking density.

[0063] Preferably, to avoid interfering with the accurate replication of surface texture and the transparency of the hardened layer 3, the hardened layer 3 contains little or no matting particles, resulting in better flexibility and continuity. It is less prone to defects such as cracking, whitening, or texture distortion during thermoforming, thus achieving a good balance between surface protection and thermoforming compatibility. Specifically, the total content of inorganic or organic particles with a median particle size D50 ≥ 0.5 μm in the hardened layer 3 is no more than 1.0 wt% of the total solid content of the hardened layer, more preferably no more than 0.5 wt%. Furthermore, when further improvement in wear resistance is required, nano-silica and / or nano-alumina with a median particle size D50 ≤ 100 nm can be introduced as reinforcing phases.

[0064] This invention decouples the functions of the microtextured mold layer 2 and the hardened layer 3, allowing the microtextured mold layer 2 to handle matte finish and the hardened layer 3 to handle protection, thus avoiding the contradiction of a single coating failing to provide both. Both layers utilize an aliphatic polyurethane system, ensuring chemical compatibility and interfacial bonding strength. Furthermore, by controlling the surface energy of the low surface energy resin in the microtextured mold layer 2, a balance is achieved between wettability during coating and ease of peeling during transfer. Ultimately, the multi-scale texture of the microtextured mold layer 2 imparts an ultra-matte gloss and a delicate feel to the hardened layer 3, while the hardened layer 2, being pure and free of coarse particles, combines excellent protective properties with thermoforming adaptability, achieving a comprehensive effect that is difficult to achieve simultaneously with existing technologies.

[0065] Furthermore, the pattern layer 4 is disposed on the side of the hardened layer 3 opposite to the microtextured mold layer 2, and is used to form decorative patterns, masking layers, color layers, or light-transmitting windows. After composite transfer, the pattern layer 4 is located between the hardened layer and the adhesive layer, and deforms together with the substrate during subsequent thermoforming and back injection molding. Therefore, in addition to meeting the requirements of pattern clarity and color stability, this layer should also have good interlayer adhesion, heat-pressing composite resistance, and crack resistance and distortion resistance during the molding process.

[0066] Preferably, the pattern layer 4 is a single-component solvent-based gravure printing ink layer. This type of ink system is mainly physically dried, suitable for continuous high-speed printing and multi-color overprinting, and can form a uniform, dense, and flexible printing layer on the film substrate. This is beneficial for ensuring decorative expressiveness while also meeting the requirements of subsequent lamination, thermoforming, and transfer processing.

[0067] More preferably, the ink resin used in the pattern layer 4 includes one or more of polyurethane resin, acrylic resin, and vinyl copolymer resin. The polyurethane resin provides flexibility and moldability; the acrylic resin provides color retention, transparency, and scratch resistance; and the vinyl copolymer resin improves pigment dispersion and adhesion to the film material. If necessary, a small amount of hydroxyl resin or adhesion-promoting resin may be introduced to enhance interlayer bonding performance.

[0068] Based on ink solids, the ink resin in pattern layer 4 preferably comprises 40–80 wt% polyurethane resin, 20–60 wt% vinyl copolymer resin, and / or acrylic resin. The pigment system may be one or more of organic pigments, inorganic pigments, carbon black, pearlescent pigments, or metallic effect pigments. The masking layer preferably uses high-opaque white or black pigments, and the light-transmitting window preferably uses a low-opaque formulation.

[0069] Furthermore, the adhesive layer 5 is disposed on the side of the pattern layer 4 opposite to the hardened layer 3, and is used to composite and transfer the functional layers such as the hardened layer 3 and the pattern layer 4 onto the surface of the ABS substrate or ABS / PC substrate. After composite transfer, the adhesive layer 5 remains in the INS film structure and maintains stable interlayer adhesion during subsequent thermoforming and injection molding processes. In this embodiment, the adhesive layer 5 preferably uses an acrylic hot melt adhesive system, which is beneficial for balancing adhesion to the substrate and the pattern layer 4, chemical resistance, and temperature cycling resistance.

[0070] Preferably, the dry film thickness of the adhesive layer 5 is 2–15 μm, more preferably 4–10 μm. This thickness range ensures that the adhesive layer has sufficient wetting and gap-filling capabilities during hot-pressing lamination, while avoiding dimensional instability, localized migration, or uneven deformation during subsequent molding processes due to excessive adhesive layer thickness.

[0071] Furthermore, the present invention provides a process for preparing an ultra-dull INS film, comprising the following steps: (1) Preparation of ultra-dull composite transfer film (11) A microtextured mold layer 2 is formed by coating the surface of the carrier film 1; Preferably, a micro-reverse coating method is used, which is suitable for low-viscosity liquids and thin-layer high-uniformity coating, and is especially suitable for flexible film substrates.

[0072] Preferably, the wet film thickness of the microtextured mold layer 2 is controlled to be 5–25 μm, more preferably 8–18 μm; the dry film thickness is controlled to be 2–15 μm, more preferably 4–10 μm.

[0073] Preferably, a segmented drying and post-curing process is adopted after coating: the first stage is 40-65℃, the second stage is 70-95℃, and the third stage is 100-130℃.

[0074] In the aforementioned segmented drying and post-curing process, in the first stage, the main elastic resin ensures uniform spreading of the wet film; in the second stage, acrylic resin and CAB resin work synergistically to accelerate surface freezing and inhibit backflow; low surface energy resin migrates and accumulates to the surface, establishing a release interface; inorganic fillers construct a micron-scale main framework; in the third stage, as the cross-linked network further grows, the resin system undergoes fine-scale phase separation due to limited compatibility, forming submicron-scale fine textures between the frameworks; organic fillers are distributed at the peaks and gaps of the framework, passivating the surface. This results in a surface possessing both a micron-scale main scattering structure and a submicron-scale diffuse reflection structure, stably imparting a low-gloss appearance and a delicate feel to the hardened layer after transfer printing.

[0075] (12) A hardened layer 3 is formed by coating the surface of the microtextured mold layer 2; Preferably, a micro-reverse coating method is used, with a wet film thickness of 5–18 μm, more preferably 6–12 μm, and a dry film thickness of 3–10 μm, more preferably 4–8 μm. After coating, a segmented drying and thermal curing process is preferably employed to bring the hardened layer to a state suitable for subsequent printing, lamination, and transfer.

[0076] (13) A pattern layer 4 is printed on the side of the hardened layer 3 that is away from the microtextured mold layer 2; Preferably, gravure printing is used; more preferably, a ten-color gravure printing machine is used to sequentially print the base color layer, decorative texture layer, masking layer, and functional window layer according to the product design requirements.

[0077] Preferably, the dry film thickness of the pattern layer 4 is 1–8 μm, more preferably 2–5 μm. This thickness range is beneficial for balancing the clarity of multicolor gravure printing, the flexibility of subsequent thermoforming, and the compatibility with the adhesive layer.

[0078] (14) An acrylic hot melt adhesive layer is formed on the side of the pattern layer 4 away from the hardened layer 3 by a micro-reverse coating method.

[0079] (2) Composite transfer printing and post-processing (21) The multilayer structure obtained in step (1) is hot-pressed and composite transferred with the substrate. During the composite transfer process, the carrier film 1 and the micro-texture mold layer 2 are peeled off, so that the hardened layer 3, the pattern layer 4 and the adhesive layer 5 are retained on the surface of the substrate layer 6, wherein the hardened layer 3 is located on the outermost surface.

[0080] Preferably, the substrate layer 6 is an ABS sheet or ABS / PC sheet with a thickness of 300 to 800 μm. This thickness range is beneficial for maintaining the overall shape stability of the sheet during subsequent thermoforming and for providing sufficient support for back injection molding.

[0081] Preferably, the composite transfer temperature is 150–200℃, the composite pressure is 0.2–0.6MPa, and the composite linear speed is 1–8m / min.

[0082] (22) The transferred sheet is further thermoformed, trimmed and back-injected to obtain an ultra-dull INS film.

[0083] To better illustrate the technical solution of this application, the following specific embodiments and comparative examples are provided.

[0084] The main raw materials and key parameters used in the embodiments and comparative examples of this invention are shown in Table 1: Table 1 Main raw materials and key parameters

[0085] In Table 2, the mold layer formulation is based on 100 parts of total resin components. The inorganic and organic fillers are additional amounts relative to these 100 parts of resin components. The crosslinking agent is calculated based on the total hydroxyl content of the system, making NCO / OH = 1.05. Unless otherwise specified, the solvents, additives, and catalysts are the same as in Example 1.

[0086] Table 2. Mold Layer Recipe (portions)

[0087] Example 1 (1) Mold layer preparation In this embodiment, the mold layer uses the following raw materials: the main elastic resin is DURANOL G3452; the hydroxyl acrylic resin is DOMACRYL 5210 75 BAc; the CAB resin is CAB-551-0.2; the low surface energy resin is MCR-C61; the inorganic filler is ACEMATT OK607; the organic filler is MicroTouch 875XF; and the crosslinking agent is Desmodur ultra N3300. The main parameters of each raw material are shown in Table 1, and the proportions of each component in the mold layer are shown in Table 2.

[0088] The additives used are: 0.8 parts of dispersant BYK-9076, 0.25 parts of wetting and leveling agent BYK-333, 0.25 parts of defoamer BYK-410, and 0.5 parts of catalyst dibutyltin dilaurate. The solvent used is butyl acetate / propylene glycol methyl ether acetate / methyl isobutyl ketone / cyclohexanone = 35 / 30 / 20 / 15 (mass ratio), adjusting the total solids content of the mold layer to 35-37 wt%. First, DOMACRYL 5210, DURANOL G3452, and CAB-551-0.2 are added to the solvent and stirred to dissolve. Then, the dispersant, ACEMATTOK 607, and MicroTouch 875XF are added, and the mixture is dispersed at high speed for 20 minutes. Subsequently, MCR-C61, wetting and leveling agent, defoamer, and catalyst are added. Finally, Desmodur ultra N3300 is added at an NCO / OH ratio of 1.05, stirred at low speed until homogeneous, and then filtered.

[0089] The obtained mold layer coating was applied to the surface of a 50μm thick PET carrier film using a micro-reverse coating method, with the wet film thickness controlled at approximately 12μm. Subsequently, the film was dried in stages at 50℃×1min, 80℃×2min, and 110℃×3min to obtain a mold layer with a dry film thickness of approximately 4μm.

[0090] (2) Preparation of hardened layer The hardened layer uses the following system: DOMACRYL 5210 75 BAc hydroxyl acrylic resin, DURANOL G3452 polycarbonate diol, and Desmodur ultra N3300 crosslinking agent. The mass ratio of DOMACRYL 5210 75 BAc to DURANOL G3452 is 72:28 based on resin solids, and the crosslinking agent is added at an NCO / OH ratio of 1.02.

[0091] The additives used are: 0.8 parts dispersant BYK-9076, 0.25 parts wetting and leveling agent BYK-333, 0.25 parts defoamer BYK-410, and 0.5 parts catalyst dibutyltin dilaurate. The solvent used is butyl acetate / propylene glycol methyl ether acetate / methyl isobutyl ketone = 40 / 35 / 25 (mass ratio), adjusting the total solids content of the hardened layer to 32-35 wt%. After dissolving the above resin in the solvent, the dispersant, wetting and leveling agent, defoamer, and catalyst are added. After stirring evenly, the crosslinking agent is added at an NCO / OH ratio of 1.02, stirred at low speed, and filtered. The resulting hardened coating is applied to the mold surface using a micro-reverse coating method, with a wet film thickness controlled at approximately 12 μm. After pre-curing at 60℃×1 min, 90℃×1 min, and 120℃×2 min, a hardened layer with a dry film thickness of approximately 8 μm is obtained.

[0092] (3) Pattern layer preparation The pattern layer uses Jiangmen Toyo ATT general-purpose thermal transfer gravure ink. The base color layer, decorative texture layer, masking layer, and window layer are sequentially printed on the back of the hardened layer using a ten-color gravure printing press. Each ink color is mixed according to the manufacturer's recommended system. After single-color printing, the inks are dried with hot air at 60–70℃, and the total dry film thickness of the pattern layer is controlled to be 2–5 μm.

[0093] (4) Preparation of adhesive layer Vitel 3200B was dissolved in a mixed solvent of methyl ethyl ketone / toluene (70 / 30, mass ratio) to prepare an adhesive layer coating with a total solids content of 21–23 wt%. This coating was applied to the surface of the patterned layer using a microgravure reverse coating method, with the dry film thickness of the adhesive layer controlled to approximately 5 μm. Drying conditions were 60℃ × 1 min, 80℃ × 1 min, and 100℃ × 2 min to obtain the adhesive layer.

[0094] (5) Composite transfer and film preparation The aforementioned multi-layer structure was hot-pressed onto a 500μm thick ABS sheet. The lamination transfer temperature was 150-200℃, the lamination pressure was 0.2-0.6 MPa, and the lamination linear speed was 1-8 m / min. After cooling, the PET carrier film and mold layer were peeled off, resulting in a transferred film structure of: ABS substrate / adhesive layer / pattern layer / hardening layer. Subsequently, the obtained film was preheated at 140±5℃ for 15-25s, then thermoformed, trimmed, and proceeded to the back injection molding process to produce the INS decorative part.

[0095] Examples 2-12 Except for the mold layer formula and the corresponding raw material selection, which were adjusted according to Table 2 and the descriptions in each example, the hardening layer, pattern layer, adhesive layer, and composite transfer process in Examples 2-12 are the same as in Example 1. Each example only describes the differences from Example 1.

[0096] Example 2 The mold layer differs from Example 1 in that: The hydroxyl acrylic resin was changed from DOMACRYL 5210 75 BA; at the same time, the amount of G3452 was appropriately reduced to maintain the resin composition ratio in Table 2.

[0097] Example 3 The mold layer differs from Example 1 in that: The main elastic resin was changed from DURANOL G3452 to DURANOL T4691.

[0098] Example 4 The mold layer differs from Example 1 in that: the main elastic resin is changed to DURANOL T4691CAB, the resin is changed to CAB-381-2, and the inorganic filler is changed to ACEMATT OK520. Example 5 The mold layer differs from Example 1 in that: The main elastic resin was changed to DURANOL G4672. The inorganic packing material was changed to ACEMATT OK520.

[0099] Example 6 The mold layer differs from Example 1 in that: The hydroxyl acrylic resin was changed to DOMACRYL 5485 75 BAc / MAK. The low surface energy resin was changed to MCR-C62. The inorganic filler was replaced with ACEMATT OK390, with a median particle size of 3.9 μm.

[0100] Example 7 The mold layer differs from Example 1 in that: The main elastic resin was changed to DURANOL T4691; the hydroxyl acrylic resin was changed to DOMACRYL 5481 75BAc; the CAB resin was changed to CAB-381-2; the low surface energy resin was changed to MCR-C62; the inorganic filler was changed to ACEMATTOK390; and the amount of 875XF was increased as shown in Table 2.

[0101] Example 8 The mold layer differs from Example 1 in that: The low surface energy resin was changed to MCR-C62, while maintaining the higher organic filler content in Table 2; the inorganic filler was OK607.

[0102] Example 9 The mold layer differs from Example 1 in that: Increase the amount of inorganic filler OK520 while maintaining a low level of organic filler.

[0103] Example 10 The mold layer differs from Example 1 in that: The main elastic resin adopts the G3452 / T4691 mixed system; the inorganic filler adopts OK390.

[0104] Example 11 The mold layer differs from Example 1 in that: The main elastic resin used is G4672; the hydroxyl acrylic resin used is DOMACRYL 5485 75 BAc / MAK; the CAB resin used is CAB-381-2; the low surface energy resin used is MCR-C62; and the amount of organic filler used is increased.

[0105] Example 12 The mold layer differs from Example 1 in that: The hydroxyl acrylic resin used is DOMACRYL 5481 75 BAc; the inorganic filler is OK520; and the amount of organic filler is increased.

[0106] Comparative Examples 1-5 Comparative Example 1 The difference from Example 1 is that: The main elastic resin was changed from polycarbonate diol DURANOL G3452 to polytetrahydrofuran diol PTMG 2000 (Mitsubishi Chemical Corporation), and the rest was the same as in Example 1.

[0107] Comparative Example 2 The difference from Example 1 is that: The amount of single-terminal dihydroxy organosilicon was reduced, and the rest was the same as in Example 1.

[0108] Comparative Example 3 The difference from Example 1 is that: Without adding CAB resin, the rest is the same as in Example 1.

[0109] Comparative Example 4 The difference from Example 1 is that: The organic filler 875XF was not added, and the inorganic filler OK520 was used, which was increased to the level shown in Table 2. The rest was the same as in Example 1.

[0110] Comparative Example 5 The difference from Example 1 is that no microtextured mold layer is provided.

[0111] A water-based release layer is first applied to the surface of the PET carrier film. The water-based release layer, by weight, includes: Michem® Emulsion 41740 55.0 parts, Bayhydrol® UH 340 / 1 15.0 parts, deionized water 28.4 parts, BYK-348 10.3 parts, TEGO® Foamex 810 0.2 parts, and ACRYSOL™ RM-8W 1.1 parts.

[0112] Then, a hardening layer is applied directly to the surface of the release layer.

[0113] After mixing the above components thoroughly, the pH of the coating solution was adjusted to 7.2–7.8 with dilute ammonia. The solution was then filtered through a 5 μm filter and applied to a 50 μm thick PET carrier film using a micro-reverse coating method, with a wet film thickness controlled at 1.5–2.5 μm. Subsequently, it was dried in stages at 70℃ for 30 s, 95℃ for 45 s, and 110℃ for 45 s to obtain a release layer with a dry film thickness of approximately 0.40–0.70 μm and a dry coating weight of approximately 0.40–0.70 g / m². A hardening layer was then directly applied to the surface of this release layer. In Comparative Example 5, the resin system for the hardening layer was the same as in Example 1, but 4.0% ACEMATT OK60 was added based on the total solids of the hardening layer, and 875XF was not added. The rest was the same as in Example 1.

[0114] The testing methods used in this embodiment of the invention are as follows, and the test results are shown in Table 3.

[0115] 60° gloss: After the sample was placed at 23±2℃ and 50±5% relative humidity for 24 hours, the 60° gloss was tested according to ISO 2813. Five positions were tested for each sample, and the average value was taken.

[0116] Surface roughness: Surface roughness was tested using a three-dimensional confocal surface profilometer, and Sa was recorded. At least three regions were tested for each sample, and the average value was taken.

[0117] Tactile feel: A blind evaluation was conducted using a 7-person training and evaluation team. Evaluators slid their index finger across the sample surface three times in a constant direction, scoring it from 1 to 5: 1 for noticeably rough; 2 for slightly rough; 3 for average; 4 for smooth; and 5 for a distinctly velvety feel. The roughness of the coating surface and friction both influenced the subjective tactile feel evaluation.

[0118] Cream tolerance: After pretreatment at 23±2℃ and 50±5% relative humidity for 24 h, the samples were tested according to the cream tolerance evaluation items in Volkswagen TL226, preferably PV 3964. During the test, 0.20 g of the cream medium to be tested was uniformly applied to the sample surface and covered with a glass plate or glass slide to ensure full contact between the medium and the sample surface; then it was placed at 40±2℃ for 24 h. After the treatment, the sample surface was wiped clean with a soft, lint-free cloth and left to stand at 23±2℃ for 2 h. The changes in gloss loss, whitening, stickiness, softening, blistering, cracking, texture damage, and feel of the sample surface were observed and recorded.

[0119] Hand cream resistance: The test was conducted according to the cream resistance method described in 6.4, where the test cream was hand cream. After the test, the changes in gloss, whitening / stickiness, surface softening, and feel of the sample surface were evaluated.

[0120] Sunscreen resistance: The cream resistance test was conducted according to the method described in 6.4, where the test cream was sunscreen. After the test, the changes in gloss, whitening, softening, loss of gloss, and feel of the sample surface were evaluated.

[0121] Media resistance: After pretreatment at 23±2℃ and 50±5% relative humidity for 24 h, the samples were tested according to the media resistance test in Volkswagen TL226 and the drop test method in DIN EN ISO 2812-4. The test media included one or more of artificial sweat, 75% ethanol, and cleaning agents. During the test, a specified amount of test media was dropped onto the sample surface and covered with a watch glass, glass slide, or non-woven fabric soaked in the test media, allowing the media to continuously act on the sample surface. Artificial sweat was preferably treated at 50±2℃ for 24 h, and 75% ethanol was preferably treated at 23±2℃ for 30 min with an application of approximately 500 g. After treatment, the sample surface was wiped clean and allowed to stand at 23±2℃ for 2 h. The loss of gloss, discoloration, whitening, stickiness, blistering, cracking, texture damage, and changes in feel of the sample surface were observed and recorded.

[0122] Artificial sweat resistance: Tested according to the medium resistance method described in 6.5, wherein the test medium is artificial sweat. Evaluate the changes in appearance and feel of the sample surface.

[0123] Alcohol resistance: Tested according to the medium resistance method described in 6.5, wherein the test medium is 75% ethanol. Evaluate changes in gloss, whitening, loss of gloss, and texture of the sample surface.

[0124] Results Evaluation: For the resistance tests to hand cream, sunscreen, artificial sweat, and alcohol, a comprehensive evaluation was conducted according to the following standards: Excellent: The sample surface showed no obvious loss of gloss, whitening, stickiness, softening, bubbling, cracking, or texture damage, and the feel remained essentially unchanged; Good: The sample surface showed slight loss of gloss or slight changes in feel, but no obvious whitening, stickiness, softening, bubbling, cracking, or texture damage; Medium: The sample surface showed relatively obvious loss of gloss, whitening, stickiness, softening, or deterioration in feel, but no serious structural damage occurred; Poor: The sample surface showed obvious whitening, severe loss of gloss, stickiness, softening, bubbling, cracking, obvious texture damage, or other serious failure phenomena.

[0125] Table 3 Test Results of Examples and Comparative Examples

[0126] As shown in Table 3, the films prepared in Examples 1, 2, 6, 7, 10, and 11 achieved a good balance between 60° gloss, surface roughness, and feel, exhibiting low gloss and a delicate velvety touch. Among them, Examples 6, 7, and 11, which used finer silica particles combined with appropriate amounts of organic fillers and single-terminated dihydroxyl silicone resin, maintained low gloss while having lower surface roughness and higher feel scores, indicating that a finer main framework structure and moderate surface smoothness adjustment are more conducive to obtaining a matte appearance and soft touch.

[0127] In comparison, the inorganic filler particles in Examples 4, 5, 9 and 12 were larger or used in higher amounts, resulting in a further reduction in the 60° gloss of the resulting surface, but an increase in surface roughness and a drier feel. This indicates that while simply enhancing the scattering of the main skeleton can effectively reduce gloss, it is not conducive to maintaining the surface smoothness.

[0128] Comparative Example 1 shows that when the main elastic resin is changed from polycarbonate diol to polyether polyol, the surface gloss is significantly increased, indicating that the polycarbonate continuous phase is more conducive to maintaining the texture of the mold layer. Comparative Example 2 shows that when the amount of single-terminated dihydroxyl silicone is too low, the surface enrichment is insufficient, and a stable low surface energy release interface cannot be established, resulting in texture damage and increased gloss during transfer peeling. Comparative Example 3 shows that after removing CAB resin, the surface freezing ability decreases, and reflow is more likely to occur, resulting in a weakening of the low gloss and fine texture effect. Comparative Example 4 shows that although increasing the amount of inorganic filler without adding organic filler can achieve a lower gloss, it will significantly increase the surface roughness, worsen the feel, and make the appearance more prone to changes under the influence of media such as hand cream and sunscreen. Comparative Example 5 further demonstrates that when no mold layer is set and only a release layer is used, and the appearance is controlled by directly adding matte powder to the hardened layer, the 60° gloss of the obtained surface is significantly higher than the ultra-matte level of the present invention, and the feel is significantly inferior to the embodiment of the present invention. This shows that the technical route of the present invention, which constructs the surface through a micro-textured mold layer and replicates the texture through a hardened layer, is more conducive to obtaining an ultra-matte appearance, a delicate touch, and better chemical resistance.

[0129] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A super-matte composite transfer film, characterized in that, It includes a carrier film, a microtextured mold layer, a hardening layer, a pattern layer, and an adhesive layer stacked in sequence: Based on solid content, the raw materials of the microtextured mold layer include 35-70 wt% elastic resin, 15-40 wt% acrylic resin, 1-10 wt% cellulose acetate butyrate resin, 3-8 wt% low surface energy resin, 1-15 wt% inorganic filler and 0.5-5 wt% organic filler. The raw material of the microtextured mold layer also includes a crosslinking agent, and the amount of the crosslinking agent is calculated based on the equivalent ratio of NCO groups to OH groups in the system of 1.02 to 1.10; The surface of the micro-textured mold layer facing the hardened layer has micro-textures, and the micro-textured mold layer also has a release function. The hardened layer is a protective layer, and its surface facing the microtextured mold layer has a mirror negative microtexture, and the gloss of the surface at 60° is not higher than 5 GU.

2. The ultra-matte composite transfer film according to claim 1, characterized in that, The elastic resin includes one or more of polyester polyols, polyether polyols, polycaprolactone polyols, polycarbonate diols, and polycarbonate-modified polyester polyols. Preferably, the elastic resin is polycarbonate diol with a number average molecular weight of 800-2000 and a hydroxyl value controlled at 55-140 mg KOH / g.

3. The ultra-matte composite transfer film according to claim 1, characterized in that, The acrylic resin is a hydroxyl acrylic resin, wherein the number average molecular weight of the acrylic resin is 3000–15000, the Tg is 15–60℃, the hydroxyl value is 60–130 mgKOH / g, and the acid value is 1–10 mgKOH / g; and / or, The cellulose acetate butyrate resin has a butyryl content of 45–55 wt%, a hydroxyl content of 1.0–2.5 wt%, and an ASTM-A viscosity of no more than 3 seconds.

4. The ultra-matte composite transfer film according to claim 1, characterized in that, The low surface energy resin includes one or more of organosilicon resin, silicon-modified acrylic resin, fluoropolymer, and silicon- or fluorine-containing block copolymer; preferably, the organosilicon resin is a polydimethylsiloxane with primary hydroxyl end capping.

5. The ultra-matte composite transfer film according to claim 1, characterized in that, The inorganic filler includes one or more of precipitated silica, thermal silica, and surface-treated precipitated silica; preferably, the median particle size D50 of the inorganic filler is 1 to 12 μm, and the D90 is not greater than 20 μm. The organic filler includes one or more of thermosetting urea-based micropowder, polyurethane microspheres, and cross-linked acrylic microspheres; preferably, the median particle size D50 of the organic filler is 1 to 12 μm.

6. The ultra-matte composite transfer film according to any one of claims 1-5, characterized in that, The raw materials for the microtextured mold layer also include solvents, which include one or more of esters, ketones and aromatic hydrocarbons; the total solid content of the raw materials for the microtextured mold layer is 25-45 wt%.

7. The ultra-matte composite transfer film according to any one of claims 1-5, characterized in that, The hardened layer comprises 60–80 wt% hydroxyl acrylic resin and 20–40 wt% polycarbonate diol; the hardened layer also includes a crosslinking agent, the amount of which is based on an NCO:OH equivalent ratio of 0.98–1.08; and / or, The raw materials of the patterned layer, on a solid basis, include 40-80 wt% polyurethane resin, 20-60 wt% ethylene copolymer resin or acrylic resin.

8. A method for preparing an ultra-dull INS film, using the ultra-dull composite transfer film according to any one of claims 1-7, characterized in that, Includes the following steps: (1) A microtextured mold layer is coated on the surface of the carrier film, and the microtextured mold layer is dried and cured in stages at 40-65℃, 70-95℃ and 100-130℃ in sequence; (2) A hardening layer is applied to the surface of the microtextured mold layer, wherein the hardening layer is a transparent protective layer; (3) Print a pattern layer on the side of the hardened layer opposite to the microtextured mold layer; (4) Apply an adhesive layer to the side of the pattern layer opposite to the hardened layer; (5) The multilayer structure obtained in step (4) is hot-pressed and composite transferred with the substrate layer, and the carrier film and the micro-texture mold layer are peeled off during the composite transfer process, so that the hardened layer, the pattern layer and the adhesive layer are retained on the substrate surface, wherein the hardened layer is located on the outermost side, and the ultra-dull INS film is obtained.

9. The preparation method according to claim 8, characterized in that, In step (5), the composite transfer temperature is 150-200℃, the composite pressure is 0.2-0.6MPa, and the composite linear speed is 1-8m / min.

10. An ultra-dull INS film, formed by transfer using the ultra-dull composite transfer film according to any one of claims 1-7, or prepared using the preparation method according to claim 8 or 9, characterized in that, It includes a substrate layer, an adhesive layer, a pattern layer and a hardening layer stacked in sequence; wherein the gloss of the outer surface of the hardening layer at 60° is not higher than 5 GU.

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