Printed pattern decorative polymer composite board and preparation method thereof

Abstract

The present invention provides a printed pattern decorative polymer composite plate and a preparation method thereof. The printed pattern decorative polymer composite plate comprises a pattern printing layer and a transparent overcoat layer formed on the surface of the pattern printing layer. The transparent overcoat layer comprises: a base layer formed by curing an acrylic resin composition to form a film. The acrylic resin composition comprises a bridge-type functionalized acrylic monomer and a multifunctional acrylic monomer. The general formula of the bridge-type functionalized acrylic monomer is R1-[SiO] n ‑Ph‑[SiO] m ‑R2, R1 and R2 are acrylate groups, n and m are integers of 2‑10, [SiO] is a siloxane segment, Ph is an aromatic ring bridging group, and the molecular structure of the multifunctional acrylic monomer has three or more acrylate groups; the interface structure layer is in situ formed on the surface of the base layer and is formed by the low surface energy additive migrating to the surface and enriching during the curing reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of functional composite boards applied to housings of household appliances such as refrigerators and washing machines, and in particular to a printed pattern decorative polymer composite board and a preparation method thereof. Background Art

[0002] Printed pattern decorative polymer (PPM) composite panels are widely used in the housings of household appliances such as refrigerators and washing machines. They typically consist of a patterned printed layer and a transparent overcoat layer. As consumer electronics and household appliances move toward higher-end and more sophisticated design, end users are increasingly demanding higher quality and durability from the exterior. This translates to higher requirements for PPM composite panels, particularly in terms of pattern retention, scratch resistance, fingerprint resistance, and long-term weather resistance. However, existing PPM composite panels suffer from a widespread performance imbalance, making it difficult to balance these performance attributes without sacrificing performance in any particular area. This has limited their further application in high-end household appliance exterior components. Summary of the Invention

[0003] In order to solve the above problems, according to a first aspect of the present invention, there is provided a printed pattern decorative polymer composite plate, comprising a pattern printing layer and a transparent overcoat layer formed on the surface of the pattern printing layer, wherein the transparent overcoat layer comprises:

[0004] The base layer is formed by curing an acrylic resin composition to form a film, wherein the acrylic resin composition comprises at least one bridge-type functional acrylic monomer and at least one multifunctional acrylic monomer, wherein the general formula of the bridge-type functional acrylic monomer is R1-[SiO] n -Ph-[SiO] m -R2, wherein R1 and R2 are acrylate groups, n and m are integers of 2-10, [SiO] is a siloxane segment, Ph is an aromatic ring bridging group, the molecular structure of the multifunctional acrylic monomer has three or more acrylate groups, and the mass ratio of the bridging functional acrylic monomer to the multifunctional acrylic monomer is 1:(1.5-2);

[0005] The interface structure layer is formed in situ on the surface of the base layer and is formed by the migration and accumulation of the low surface energy additive to the surface during the curing reaction.

[0006] Optionally, the number average molecular weight of the bridge-type functionalized acrylic monomer is 400 g / mol-1500 g / mol, and the number average molecular weight of the multifunctional acrylic monomer is 200 g / mol-1000 g / mol;

[0007] The functional group molar ratio of the bridge-type functional acrylic monomer to the multifunctional acrylic monomer is (0.8-1.5):1.

[0008] Optionally, the aromatic ring bridging group is a diphenyl group, a biphenyl group, a triphenylmethane group or a fluorenyl group structure.

[0009] Optionally, the low surface energy additive contains Si-O-Si and / or (CF2) in the main chain. n The amphiphilic block polymer of the hydrophobic segment has a functional group at its end or side chain that can undergo a cross-linking reaction with the acrylic resin composition.

[0010] Optionally, the mass ratio of the hydrophobic segment to the resin-philic segment in the low surface energy additive is (1-2): 1;

[0011] The number average molecular weight of the amphiphilic block polymer is 800 g / mol-5000 g / mol.

[0012] Optionally, the mass fraction of the Si-O-Si hydrophobic segment in the amphiphilic block polymer is 5wt%-15wt%, and the (CF2) n The mass fraction of the hydrophobic segment in the amphiphilic block polymer is 2wt%-10wt%.

[0013] Optionally, the transparent overcoat layer comprises the following components in parts by weight: 50-90 parts of an acrylic resin composition, 0.5-5 parts of a low surface energy additive, 0.5-3 parts of a photoinitiator, 0.3-2 parts of a light stabilizer, and 0.1-3 parts of a polar monomer.

[0014] Optionally, the polar monomer is an acrylate monomer containing a carboxyl group, a hydroxyl group, an amide group or a sulfonate structure;

[0015] The photoinitiator is a combination of one or more of α-hydroxy ketones, alkyl phenones, phosphorus oxides and phenyl diketones;

[0016] The light stabilizer is a combination of one or more of an ultraviolet absorber, a hindered amine light stabilizer and an organic phosphate antioxidant.

[0017] According to a second aspect of the present invention, there is provided a method for preparing the aforementioned printed pattern decorative polymer composite plate, comprising the following steps:

[0018] uniformly mixing the components in the transparent overcoat layer to obtain a coating liquid;

[0019] Applying the coating liquid on the surface of the pattern printing layer to form a wet film with a thickness of 20 μm-100 μm, and standing at 25° C.-40° C. for 30 seconds-180 seconds;

[0020] Performing a pre-curing treatment on the wet film under a first power ultraviolet light source, and then performing a main curing treatment under a second power ultraviolet light source to form a cured film layer;

[0021] The cured film layer is heated at 60° C.-90° C. for 10 min-30 min to obtain the transparent overcoat layer.

[0022] Optionally, before applying the coating liquid on the surface of the pattern printing layer by blade coating, the following steps are further included:

[0023] The pattern printing layer is subjected to surface polarity activation treatment to introduce polar groups onto the surface of the pattern printing layer.

[0024] According to the solution of the present invention, by introducing a bridge-type functionalized acrylic monomer having a siloxane backbone and an aromatic ring bridge structure into the transparent overcoat layer and synergizing it with a multifunctional acrylic monomer in the curing reaction, a three-dimensional cross-linked network structure with coordinated flexibility and rigidity can be constructed in the transparent overcoat layer, which can significantly improve the overall performance of the transparent overcoat layer and achieve unexpected results. Specifically, if only multifunctional acrylic monomers are used, although high crosslinking density and good hardness can be achieved, the film layer is not tough enough due to its rigid structure, and is prone to cracking or interfacial damage under the action of thermal shock or lamination stress, making it difficult to meet the stress buffering requirements caused by thermal expansion differences in the multilayer structure. If bridge-type functionalized acrylic monomers are used alone, although they have flexible segments that help release interfacial stress, due to their low functionality, the cured film network structure is loose, resulting in insufficient film density and mechanical strength. The two acrylic monomers are compounded in a specific mass ratio to achieve structural synergy between flexible adjustment and high crosslinking degree, which not only significantly improves the scratch resistance of the film layer, but also effectively alleviates the warping and delamination problems caused by thermal expansion mismatch between the pattern printing layer and the pattern printing layer. Furthermore, it is generally believed by those skilled in the art that polymers containing siloxane segments have low polarity, making it difficult to achieve good interfacial bonding with polar patterned printed layers. Furthermore, the high thermal expansion coefficient of their soft segments can easily lead to stress concentration in multilayer structures, causing film warping or delamination. Therefore, they are generally unsuitable as the backbone material for overcoat layers. However, embodiments of the present invention incorporate rigid aromatic bridging (-Ph-) groups into the siloxane segments for segment adjustment. The aromatic bridging groups, located between two siloxane segments, enhance the molecular rigidity and conformational regularity of the entire segment, effectively strengthening the interfacial bonding of the transparent overcoat layer to the patterned printed layer. These aromatic bridging groups evenly disperse stress conduction pathways during the curing process, reducing localized stress concentration in both rigid and flexible regions and preventing film warping or delamination. Furthermore, the aromatic bridging groups and siloxane segments are highly stable, both resistant to photooxidative degradation and exhibiting excellent UV stability. Moreover, an interface structure layer can be formed in situ on the surface of the base layer during the curing process, and is formed by the low surface energy additive migrating to the surface and enriching during the curing reaction, thereby achieving excellent anti-fingerprint and anti-pollution capabilities.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic flow chart of a method for preparing a printed pattern decorative polymer composite plate according to one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with specific embodiments.

[0028] Embodiments of the present invention provide a printed pattern decorative polymer (PPM) composite board for use in the decorative structure of the housings of household appliances such as refrigerators and washing machines. These PPM composite boards meet multiple performance requirements, including excellent pattern retention and scratch resistance, excellent anti-fingerprint and anti-fouling properties, good interlayer thermal expansion matching, and long-term yellowing resistance.

[0029] To address the above challenges, the present invention provides a PPM composite panel that simultaneously meets these multiple performance requirements. The PPM composite panel comprises a patterned printed layer and a transparent overcoat layer formed on the surface of the patterned printed layer. The transparent overcoat layer comprises a base layer and an interface structure layer. The base layer is formed by curing an acrylic resin composition, which comprises at least one bridge-functionalized acrylic monomer and at least one multifunctional acrylic monomer. The bridge-functionalized acrylic monomer has the general formula R1-[SiO] n -Ph-[SiO] m -R2, where R1 and R2 are acrylate groups, n and m are integers of 2-10, [SiO] is a siloxane segment, Ph is an aromatic ring bridging group, the multifunctional acrylic monomer has three or more acrylate groups in its molecular structure, and the mass ratio of the bridging functional acrylic monomer to the multifunctional acrylic monomer is 1:(1.5-2). The interface structure layer is formed in situ on the surface of the substrate layer, formed by the migration and accumulation of the low surface energy additive to the surface during the curing reaction.

[0030] According to the solution of the embodiment of the present invention, by introducing a bridge-type functionalized acrylic monomer having a siloxane backbone and an aromatic ring bridge structure into the transparent overcoat layer and synergizing it with a multifunctional acrylic monomer to participate in the curing reaction, a three-dimensional cross-linked network structure with coordinated flexibility and rigidity can be constructed in the transparent overcoat layer, which can significantly improve the overall performance of the transparent overcoat layer and achieve unexpected results. Specifically, if only a multifunctional acrylic monomer is used, although a high cross-linking density and good hardness can be achieved, the film layer is not tough enough due to its rigid structure, and is prone to cracking or interfacial damage under the action of thermal shock or lamination stress, making it difficult to meet the stress buffering requirements caused by thermal expansion differences in the multilayer structure. If a bridge-type functionalized acrylic monomer is used alone, although it has a flexible chain segment that helps to release interfacial stress, due to its low functionality, the cured film network structure is loose, resulting in insufficient film density and mechanical strength. The two acrylic monomers are compounded in a specific mass ratio to achieve structural synergy of flexible adjustment and high cross-linking degree, which not only significantly improves the scratch resistance of the film layer, but also effectively alleviates the warping and delamination problems caused by thermal expansion mismatch between the pattern printing layer and the pattern printing layer. Furthermore, it is generally believed by those skilled in the art that polymers containing siloxane segments have low polarity, making it difficult to achieve good interfacial bonding with polar patterned printed layers. Furthermore, the high thermal expansion coefficient of their soft segments can easily lead to stress concentration in multilayer structures, causing film warping or delamination. Therefore, they are generally unsuitable as the backbone material for overcoat layers. However, embodiments of the present invention incorporate rigid aromatic bridging (-Ph-) groups into the siloxane segments for segment adjustment. The aromatic bridging groups, located between two siloxane segments, enhance the molecular rigidity and conformational regularity of the entire segment, effectively strengthening the interfacial bonding of the transparent overcoat layer to the patterned printed layer. These aromatic bridging groups evenly disperse stress conduction pathways during the curing process, reducing localized stress concentration in both rigid and flexible regions and preventing film warping or delamination. Furthermore, the aromatic bridging groups and siloxane segments are highly stable, both resistant to photooxidative degradation and exhibiting excellent UV stability. Moreover, an interface structure layer can be formed in situ on the surface of the base layer during the curing process, and is formed by the low surface energy additive migrating to the surface and enriching during the curing reaction, thereby achieving excellent anti-fingerprint and anti-pollution capabilities.

[0031] The siloxane segment is preferably an organosilicon structural unit with a flexible backbone, containing repeating Si-O-Si bonds. It is a key segment for regulating the flexibility and thermal stress release capabilities of the transparent overcoat layer's molecular network. The siloxane segment must meet multiple performance requirements. For example, it must have a low glass transition temperature and good segmental freedom to enhance the structural compliance of the transparent overcoat layer under conditions such as thermal shock or hot press molding, thereby reducing the risk of failures such as warping, cracking, or delamination. Furthermore, the siloxane segment must have a linear or regular oligomeric structure to ensure the density and conformational stability of the network structure during film formation. The molecular structure of the siloxane segment must also avoid containing easily hydrolyzed or volatile functional groups, such as Si-OH or low-molecular-weight Si-OR, where R is methyl or ethyl, to prevent hygroscopic expansion, migration, or degradation failure at the interface of the transparent overcoat layer after curing. Furthermore, the siloxane segment must possess good heat resistance, UV aging resistance, and optical transparency to ensure performance and appearance stability during long-term service. The use of siloxane segments with this structure not only improves the stress-buffering capacity of the transparent overcoat layer against thermal expansion gradients in the multilayer structure, but also, through synergistic connection with aromatic ring bridging groups, allows for the construction of a three-segmented structural sequence of flexible segment-rigid bridge-flexible segment at the molecular scale. This achieves molecular-level flexible-rigid synergy and conformational control, thereby enhancing the continuity and service stability of the crosslinked network. In some embodiments, the siloxane segments are preferably linear polydimethylsiloxane (PDMS) segments, more preferably oligosiloxane structures with a degree of polymerization of 2 to 10. This structure maintains high flexibility and low Tg while providing good interfacial compliance and transparency, making it suitable for connection with aromatic ring bridging groups to form a stable conformational network. The degrees of polymerization n and m of the siloxane segments in the bridge-functionalized acrylic monomer are both integers of 2-10, preferably 3-6. The sum of n and m is 4-12, preferably 6-10. This degree of polymerization range can ensure that the siloxane segments have sufficient flexibility and segment freedom, while maintaining the density and structural stability of the cured network while maintaining the cross-linking reaction activity.

[0032] The aromatic ring bridging group is preferably an aromatic structural unit with a conjugated structure and a regular molecular conformation. The aromatic ring bridging group needs to meet multiple conditions. For example, the aromatic ring bridging group needs to have high molecular rigidity and a clear conjugated main chain structure, which is beneficial to improving the dimensional stability and deformation resistance of the transparent overcoat layer. For example, the molecular structure of the aromatic ring bridging group is required to be regular so as to be suitable as a rigid support unit connecting two siloxane segments, thereby improving the conformational stability of the cross-linked network in the transparent overcoat layer. In addition, the aromatic ring bridging group needs to have excellent chemical stability, a thermal decomposition temperature of not less than 250°C, good resistance to ultraviolet aging and yellowing, and does not contain hydrophilic or easily oxidized functional groups to avoid interface instability or film performance degradation caused by moisture absorption or chemical degradation. In some embodiments, the aromatic ring bridging group is preferably a diphenyl, biphenyl, triphenylmethane or fluorenyl structure.

[0033] The acrylate group is preferably an ester functional group with a polymerizable unsaturated carbon-carbon double bond structure, which can cooperate with a multifunctional acrylic monomer to participate in a free radical polymerization reaction under the action of a photoinitiator, thereby forming a stable cross-linked network structure during the curing process. The acrylate group must meet multiple structural and performance requirements. For example, the group needs to have good reactivity to ensure that the film layer is cured in a short time, improve coating efficiency and production adaptability. For example, the chain segment structure of the group needs to have a certain degree of flexibility or controllability to adjust the crosslinking density and stress buffering capacity of the cured film layer to prevent the film layer from cracking or warping during thermal processing. In addition, the acrylate group also needs to have good thermal and light stability and is not prone to degradation, yellowing, or migration after curing. At the same time, the acrylate group structure cannot contain volatile, highly hydrophilic functional groups or functional groups that are easily opened under heat or light conditions to avoid failure behaviors such as hygroscopic expansion, interfacial damage, or molecular chain deconstruction after film formation. In some embodiments, the acrylate group is preferably a methacrylate structure, more preferably a methacrylate structure with hydroxypropyl, polyether, or silicone segments.

[0034] The bridging functionalized acrylic monomer can be, for example, a bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer, a dual-terminated methacrylate-terminated polydimethylsiloxane-fluorenyl-polydimethylsiloxane monomer, or a bis(methacrylate)-terminated polydimethylsiloxane-triphenylmethane monomer. The acrylic resin composition can include at least one of these bridging functionalized acrylic monomers.

[0035] The preparation method of the bridged functionalized acrylic monomer comprises:

[0036] Step 1: Provide amino-terminated polydimethylsiloxane with the general formula H2N-[Si(CH3)2O]n -NH2, wherein n is an integer from 2 to 10;

[0037] Step 2: reacting the amino-terminated polydimethylsiloxane with a diisocyanate compound at 40° C. to 80° C. in the presence of an inert solvent and a catalyst to generate an isocyanate-terminated polysiloxane intermediate;

[0038] Step 3: reacting the isocyanate-terminated polysiloxane intermediate with a diol compound containing an aromatic ring structure to introduce an aromatic ring bridging structure to form a bridged polysiloxane structure having a bridged skeleton, wherein the bridged polysiloxane structure has a hydroxyl or amino terminal;

[0039] Step 4: In the presence of an alkaline catalyst at 0°C-40°C, the bridged polysiloxane structure is subjected to an esterification reaction or an addition reaction with a capping agent having an acrylate group to introduce a terminal acrylate functional group to generate the target bridged functionalized acrylic monomer.

[0040] In step 2, the diisocyanate compound is selected from isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), or a combination thereof. In step 3, the diol compound is selected from biphenyl diol, fluorene diol, triphenylmethane diol, etc. In step 4, the end-capping agent is selected from methacryloyl chloride, 2-hydroxypropyl methacrylate (HPMA), or other monomers having a polymerizable double bond.

[0041] In one embodiment, the preparation method of the bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer comprises:

[0042] Step S1, under nitrogen protection, heating a mixed solution of amino-terminated polydimethylsiloxane, isophorone diisocyanate, dibutyltin dilaurate and anhydrous toluene to 40° C.-80° C. to generate an isocyanate-terminated polysiloxane intermediate;

[0043] Step S2, adding 4,4'-biphenyl dimethanol and dibutyltin dilaurate to the reaction system of step S1, reacting at 60°C-80°C for 2h-4h to generate a symmetrical structure of polydimethylsiloxane-biphenyl-polydimethylsiloxane;

[0044] In step S3, after the reaction system in step S2 is cooled to room temperature, 2-hydroxypropyl methacrylate, 4-dimethylaminopyridine, triethylamine, and a reaction solvent are added under an ice bath to react to obtain a bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer.

[0045] In one embodiment, the preparation method of the dual-end methacrylate-terminated polydimethylsiloxane-fluorenyl-polydimethylsiloxane structural monomer is substantially the same as that of the aforementioned bis(methacryloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer, except that 4,4'-biphenyl dimethanol in step S2 is replaced with 9H-fluorene-9,9-dimethanol. The preparation method of the bis(methacrylate)-terminated polydimethylsiloxane-triphenylmethane structural monomer is also substantially the same as that of the aforementioned bis(methacryloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer, except that 4,4'-biphenyl dimethanol in step S2 is replaced with p-phenylene glycol.

[0046] In some embodiments, the number average molecular weight of the bridged functionalized acrylic monomer is 400 g / mol to 1500 g / mol, for example, 400 g / mol, 800 g / mol, 1000 g / mol, 1200 g / mol, or 1500 g / mol, or any other value between 400 g / mol and 1500 g / mol. This molecular weight range ensures that the siloxane segments possess sufficient flexibility to enhance the overcoat's ability to buffer interfacial thermal stress, while also avoiding the problems of reduced crosslinking density, reduced reaction efficiency, and excessively high thermal expansion coefficient of the film layer caused by excessively long segments.

[0047] The multifunctional acrylic monomer is preferably capable of synergistically participating in a free radical polymerization reaction with a bridging-type functionalized acrylic monomer during the photocuring process to form a dense and highly cross-linked polymer network in the transparent overcoat layer. The multifunctional acrylic monomer needs to meet multiple structural and performance requirements. For example, the monomer needs to have a high cross-linking functionality and polymerization reaction activity to achieve high-efficiency curing in a short time and construct a stable and dense three-dimensional cross-linked network. For another example, the molecular configuration of the multifunctional acrylic monomer should be regular, symmetrical or highly branched to ensure that the cross-linking points are evenly distributed in space. The polymerizable functional group introduced into the multifunctional acrylic monomer is preferably an unsaturated ester group having a polymerizable carbon-carbon double bond, specifically an acrylate group or a methacrylate group, and the introduction of functional groups with low reaction activity such as vinyl ether, acrylamide, etc. should be avoided to avoid affecting the curing efficiency or reducing the density of the film layer. In addition, the multifunctional acrylic monomer must also possess excellent thermal stability and light aging stability. Its thermal decomposition temperature is preferably not less than 250°C, and it is not susceptible to yellowing, oxidative degradation, or functional group cleavage under ultraviolet radiation or high temperature environments. At the same time, its structure cannot contain hydrophilic groups or low-molecular-weight segments to avoid interfacial instability such as hygroscopic expansion, migration and precipitation in the cured film during service, ensuring long-term performance. In some embodiments, the multifunctional acrylic monomer is preferably a functionalized monomer with a regular molecular structure, high polymerization activity, and excellent thermal stability, such as trimethylolpropane triacrylate (TMPTA), pentaerythritol tetraacrylate (PETA), or hexanediol diacrylate (DPHA). The acrylic resin composition may include at least one of the above multifunctional acrylic monomers.

[0048] In some embodiments, the multifunctional acrylic monomer has a number average molecular weight of 200 g / mol to 1000 g / mol, for example, 200 g / mol, 300 g / mol, 500 g / mol, 800 g / mol, or 1000 g / mol, or any other value between 200 g / mol and 1000 g / mol. This molecular weight range helps achieve a balance between high reactivity and a reasonable crosslink density during the curing process. A molecular weight below this range can lead to film embrittlement, interfacial instability, or small molecule migration, while a molecular weight above this range can lead to reduced crosslinking efficiency, decreased film density, and weakened mechanical properties.

[0049] In one embodiment, the mass ratio of the bridging functionalized acrylic monomer to the multifunctional acrylic monomer is 1:1.5, 1:1.8, or 1:2, or any other value between 1:(1.5-2). This ratio range helps to build a high-density cross-linked network while introducing moderately flexible segments, thereby adjusting the rigidity-flexibility balance and stress distribution of the film layer.

[0050] It should be noted that the final structural formula is R1-[SiO] n-Ph-[SiO] m Before using the bridged functionalized acrylic monomer of -R2 as one of the core raw materials for the transparent overcoat layer, the inventors conducted a large number of experimental attempts and structural screening work. For example, in order to improve the anti-warping ability of the transparent overcoat layer of the PPM composite board under hot and cold shock conditions, attempts were made to introduce different flexible modified components into the multifunctional acrylic monomer system, such as polyether acrylates, polyester toughening monomers and oligomer filling additives, in an attempt to enhance the flexibility of the film layer. However, studies have found that although this type of modification method can alleviate the cracking of the film layer to a certain extent, it is often accompanied by problems such as decreased cross-linking density, insufficient film density, decreased adhesion and poor thermal aging stability, making it difficult to achieve a balance between mechanical properties and service stability.

[0051] In order to further control the thermal expansion characteristics of the overcoat layer, the inventors tried to introduce linear polydimethylsiloxane (PDMS)-type monomers, such as PDMS-diacrylate and PDMS-dimethacrylate. However, studies have shown that due to the excessive flexibility of the molecules, phase separation regions are easily formed in the cured network, resulting in uneven shrinkage of the film layer, surface precipitation or decreased optical transparency, and the polarity of the Si-O chain segment and the pattern printing layer interface does not match, resulting in severe lack of adhesion.

[0052] After extensive research failed to simultaneously address issues such as film flexibility regulation, cross-linking density, dimensional stability, and interfacial adhesion, the inventors stumbled upon a materials screening discovery: introducing highly conjugated and rigid aromatic ring bridging groups, such as biphenyl, triphenylmethane, and fluorenyl, into the PDMS segments, and employing a symmetrically terminated bifunctional acrylate structure design, not only can the conformational stability of the siloxane segments be significantly improved, but a regular, dense, and flexible-rigid synergistic structure can also be formed within the polymer network. Further verification revealed that this type of bridging-type functionalized acrylic monomer exhibited good reactivity and network continuity during the polymerization process, and the resulting transparent overcoat exhibited comprehensive performance far superior to traditional modification pathways in terms of scratch resistance, long-term weather resistance, pattern retention, and interlayer thermal expansion matching.

[0053] In some embodiments, the low surface energy additive contains Si-O-Si and / or (CF2) in the main chain nThe amphiphilic block polymer of hydrophobic segment, its end or side chain contains the functional group that can cross-link reaction with acrylic resin composition.The amphiphilic block polymer has hydrophobic segment and parent resin segment.In one embodiment, the mass ratio (1-2) of hydrophobic segment and parent resin segment: 1, for example, can be 1: 1,1.5: 1 or 2: 1, can also be (1-2): any other value in 1.This mass ratio range helps to ensure that the hydrophobic segment effectively migrates on the film surface and gives it anti-fingerprint, antifouling properties, while maintaining the compatibility between low surface energy auxiliary agent and acrylic resin composition, avoids the film defect caused by phase separation. The number average molecular weight of the amphiphilic block polymer is 800 g / mol to 5000 g / mol, for example, 800 g / mol, 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, or 5000 g / mol, or any other value between 800 g / mol and 5000 g / mol. Amphiphilic block polymers with a number average molecular weight below 800 g / mol are easy to migrate but may not participate sufficiently during the UV curing process, resulting in incomplete crosslinking of the interface layer or easy precipitation of the film. Amphiphilic block polymers with a number average molecular weight above 5000 g / mol have excessively long molecular chains, increased viscosity, poor mixing, decreased migration efficiency, and difficulty forming a continuous low-surface-energy-rich phase.

[0054] In certain embodiments, the mass fraction of the Si-O-Si hydrophobic segment in the amphiphilic block polymer is 5wt%-15wt%, for example, it can be 5wt%, 10wt% or 15wt%, or any other value in 5wt%-15wt%. When the mass fraction is less than 5wt%, the Si-O-Si hydrophobic segment is insufficient, and it is difficult to effectively migrate to the surface of the film during the curing process, resulting in an insignificant decrease in surface energy. When the segment content exceeds 15wt%, the hydrophobic segment is too much and will weaken the compatibility with the acrylic resin composition, resulting in phase separation or surface precipitation during the curing process, affecting the uniformity, adhesion and long-term stability of the film. Therefore, the mass fraction range of 5wt%-15wt% helps to achieve a good surface regulation effect while maintaining the dispersibility and reaction adaptability of the amphiphilic block polymer in the acrylic resin composition system.

[0055] The Si-O-Si hydrophobic segment is preferably a siloxane structural unit with a linear configuration, flexible segment characteristics and low polarity, which can migrate and accumulate on the surface during the curing process, thereby constructing an interface structure layer and giving the transparent overcoat layer excellent anti-fingerprint performance and surface anti-pollution ability. The Si-O-Si hydrophobic segment needs to meet multiple structural and performance requirements. For example, the hydrophobic segment needs to have high flexibility and low polarity to reduce the surface free energy of the transparent overcoat layer and improve its repellency to oil stains and water stains. At the same time, the hydrophobic segment also has good segment mobility and compatibility to ensure its directional migration ability during the curing process and the synergistic blending effect with other components in the acrylic resin composition system. The Si-O-Si hydrophobic segment is preferably a linear polydimethylsiloxane segment, and its degree of polymerization is preferably 2-10, more preferably 3-6, so as to ensure sufficient hydrophobicity and flexibility while avoiding the compatibility reduction or phase separation caused by excessive segment length. In addition, the Si-O-Si hydrophobic segment must have good thermal stability and photooxidation stability, and is not easily degraded, migrated or precipitated under service conditions such as UV curing, high-temperature baking or outdoor exposure.

[0056] In some embodiments, the (CF2) n The mass fraction of the hydrophobic segment in the amphiphilic block polymer is 2 wt%-10 wt%, for example, 2 wt%, 3 wt%, 5 wt%, 8 wt% or 10 wt%, or any other value between 2 wt% and 10 wt%. n When the mass fraction of the hydrophobic segment is less than 2wt%, the effective hydrophobic segment content in the polymer is insufficient, making it difficult for the hydrophobic segment to fully migrate and accumulate on the surface of the film during the curing process, resulting in a limited decrease in the interfacial surface energy. When the mass fraction of the hydrophobic segment exceeds 10wt%, due to the (CF2) n The hydrophobic segment has high hydrophobicity and strong low polarity. Too high a content will affect its compatibility with the acrylic resin composition system, and easily cause phase separation, surface precipitation or unevenness of the cured film structure. Therefore, (CF2) n Controlling the mass fraction of the hydrophobic segment in the amphiphilic block polymer within the above range helps to enhance the surface hydrophobic effect without affecting the stability of the system, improve the anti-pollution properties and surface cleanability of the transparent overcoat layer, and maintain good dispersibility and curing synergy between the amphiphilic block polymer and the acrylic resin composition system.

[0057] In some embodiments, the resin-affinity chain segment is preferably a polymer structural unit with good polarity matching and molecular compatibility, which can achieve efficient interface wetting and molecular-level fusion with the acrylic resin composition. The resin-affinity chain segment needs to meet multiple structural and performance requirements. For example, its main chain structure needs to have certain flexibility and molecular polarity to enhance the blending stability in the acrylic resin composition system and avoid microphase separation or interface peeling of the amphiphilic block polymer. In addition, the end or side chain of the resin-affinity chain segment introduces a functional group that can undergo a cross-linking reaction with the acrylic resin composition, so that it can undergo a free radical cross-linking reaction with the monomer, oligomer or prepolymer in the acrylic resin composition under light-curing conditions, thereby stably anchoring the low surface energy additive in the cross-linked network of the transparent overcoat layer, avoiding the problem of anti-fouling performance attenuation or interface instability caused by migration and precipitation during long-term service. The polymerizable functional groups suitable for this type of resin-affinity chain segment include acrylate, methacrylate, epoxy, isocyanate, hydroxyl or allyl, etc., preferably acrylate and methacrylate. In some embodiments, the resin-affinic segment can be a modified polyester, polyether, polyurethane, or acrylic polymer structural unit, preferably a polyether segment with double-bond end modifications, such as hydroxyl-terminated polypropylene oxide (PEO) and polybutylene oxide (PBO) structural units. This type of resin-affinic segment not only ensures good dispersibility and reactivity of the amphiphilic block polymer in the acrylic resin composition system, but also enables stable anchoring of low-surface energy components during the curing process, maintaining the long-term stability of the film's anti-fingerprint and anti-fouling properties, as well as its interfacial adhesion properties.

[0058] In some embodiments, the low surface energy additive may be, for example, a polyether-modified silicone acrylate block polymer, etc. The polyether-modified silicone acrylate block polymer may be, for example, Silmer ACR series, CoatOSil 1770, or Shin-Etsu X-22 series.

[0059] The low surface energy additive can also be prepared by existing methods. In one embodiment, the low surface energy additive can be, for example, a fluorosilicone copolymerized amphiphilic block polymer. The preparation method of the fluorosilicone copolymerized amphiphilic block polymer comprises the following steps:

[0060] Aminopropyl-terminated polydimethylsiloxane (NH2-PDMS-NH2) is reacted with an isocyanate coupling agent under inert gas protection at 60-80°C for 1-2 hours to generate an isocyanate-terminated intermediate;

[0061] Introducing a hydroxyl-containing polyether chain-philic segment into the intermediate, and continuing the reaction at 60°C-80°C for 2h-4h to form a block structure monomer whose main chain includes a Si-O-Si hydrophobic segment and a polyether chain-philic segment;

[0062] The above product is co-reacted with a hydroxyl-containing acrylic ester monomer in the presence of a catalyst at 50° C.-70° C. for 1 h-3 h to introduce terminal acrylic ester functional groups to obtain the target amphiphilic block polymer.

[0063] In some embodiments, the transparent overcoat layer comprises the following components in parts by weight: 50-90 parts of an acrylic resin composition, 0.5-5 parts of a low-surface-energy additive, 0.5-3 parts of a photoinitiator, 0.3-2 parts of a light stabilizer, and 0.1-3 parts of a polar monomer. The weight of the acrylic resin composition can be, for example, 50, 60, 70, 80, or 90 parts, or any other value between 50 and 90 parts. The weight of the low-surface-energy additive can be, for example, 0.5, 1, 2, 3, 4, or 5 parts, or any other value between 0.5 and 5 parts. The weight of the photoinitiator can be, for example, 0.5, 1, 2, or 3 parts, or any other value between 0.5 and 3 parts. The weight of the light stabilizer can be, for example, 0.3, 0.5, 1, or 2 parts, or any other value between 0.3 and 2 parts. The weight percentage of the polar monomer can be, for example, 0.1 part, 0.5 part, 1 part, 2 parts or 3 parts, or any other value between 0.1 and 3 parts.

[0064] The photoinitiator preferably possesses a structure with high photoinitiation efficiency and low yellowing tendency to ensure rapid polymerization initiation under UV irradiation and form a dense crosslinked network, while also avoiding adversely affecting the optical properties of the transparent overcoat layer. In some embodiments, the photoinitiator is a combination of one or more of α-hydroxyketones, alkylphenones, phosphorus oxides, and phenyl diketones. α-hydroxyketone photoinitiators, such as 1-hydroxycyclohexylphenyl ketone (Irgacure 184), offer excellent initiation rates and adaptability. Alkylphenones, such as 2-phenyl-2-dimethylamino-1-(4-methylphenyl)-1-propanone (Irgacure 369), can enhance cure depth and thick film reactivity. Phosphorus oxides, such as bis(2,4,6-trimethylbenzoyl)oxyphenylphosphine oxide (TPO), offer high initiation efficiency and low yellowing tendency, making them suitable for highly transparent coating systems. Phenyl diketones, such as benzoin and benzoin dimethyl ether, are useful for enhancing activation efficiency and improving polymerization uniformity. In some preferred embodiments, in order to take into account the curing rate, film transparency and light aging stability, the photoinitiator is preferably a composite system of TPO and Irgacure 184, or a small amount of Irgacure 907 is further introduced to regulate the initiation response in different wavelength ranges and optimize the photocuring process of the entire transparent cover layer.

[0065] In some embodiments, the light stabilizer is a combination of one or more of a UV absorber, a hindered amine light stabilizer, and an organophosphate antioxidant. This type of light stabilizer can inhibit polymer degradation reactions triggered by high-energy UV light through a synergistic mechanism. UV absorbers selectively absorb UV light in the 280nm-400nm band and convert it into low-energy heat, effectively shielding against light-induced degradation pathways. Preferred are benzotriazole, triazine, or phenylphenone structures, such as Tinuvin 328, UV-329, or Cyasorb UV-1164. Hindered amine light stabilizers (HALS) slow the aging process of materials by capturing free radicals and interrupting the degradation chain reaction. Preferred are cyclic piperidine structures, such as bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate (Tinuvin 770) or Chimassorb 944. An organophosphate antioxidant, such as tris(2,4-di-tert-butylphenyl)phosphite (Irgafos 168), can inhibit peroxide formation under UV irradiation, preventing thermal oxidative degradation of the polymer backbone. In some preferred embodiments, the light stabilizer is a combination of a UV absorber and a hindered amine light stabilizer. Further combining this with an organophosphate antioxidant can achieve a stronger light-heat synergistic stabilization effect.

[0066] In some embodiments, the polar monomer is preferably an acrylate compound with high polarity and good polymerization reactivity, containing polar functional groups such as carboxyl (-COOH), hydroxyl (-OH), amide (-CONH2), or sulfonate (-SO3R) groups. These polar monomers can effectively enhance the compatibility between components in the acrylic resin composition and strengthen the polar forces within the polymer network, thereby improving the mechanical strength and interfacial adhesion of the transparent overcoat layer. Specifically, the carboxyl and hydroxyl functional groups can participate in hydrogen bonding or coupling reactions during the curing process, enhancing the internal crosslink density and structural stability of the film. The amide group provides excellent heat resistance and polarity matching, which helps improve the dimensional stability of the transparent overcoat layer in high-temperature environments. The sulfonate structure, due to its unique electronic properties and ionization potential, can further enhance the polar interactions between polymer chains, improving the wettability and adhesion of the overcoat layer to polar substrates such as the patterned printed layer. In some preferred embodiments, the polar monomer is selected from one of the following structural monomers or a mixture thereof: hydroxyethyl acrylate (HEA), carboxyethyl acrylate (CEA), acrylamide (AAm), sodium 2-sulfonate of acrylic acid (SPEA-Na), etc. These polar monomers further enhance the service stability and interfacial adhesion reliability of the material while ensuring the reactivity of the system and the density of the film layer.

[0067] Figure 1FIG1 shows a schematic flow chart of a method for preparing a PPM composite board according to an embodiment of the present invention, wherein the PPM composite board is the composite board described above. Figure 1 As shown, the preparation method comprises:

[0068] Step S100, uniformly mixing the components in the transparent overcoat layer to obtain a coating liquid;

[0069] Step S200 , applying the coating liquid on the surface of the pattern printing layer to form a wet film with a thickness of 20 μm-100 μm, and leaving it at 25° C.-40° C. for 30 seconds-180 seconds;

[0070] Step S300 , performing a pre-curing treatment on the wet film under a first power ultraviolet light source, and then performing a main curing treatment under a second power ultraviolet light source to form a cured film layer;

[0071] In step S400 , the cured film layer is heated at 60° C. to 90° C. for 10 min to 30 min to obtain a transparent overcoat layer.

[0072] According to the solution of the embodiment of the present invention, by allowing the formed wet film to stand in a temperature range of 25°C-40°C, it helps the low surface energy additive molecules in the system to migrate and accumulate toward the surface of the film layer before a substantial polymerization reaction occurs, thereby effectively avoiding the retention of such additives inside the film layer due to direct curing and affecting the surface properties. By setting up a UV irradiation program including two stages, pre-curing and main curing, stage-by-stage control of the curing process can be achieved. Among them, the pre-curing stage uses relatively low energy UV irradiation to complete the directional migration process of the surface energy additive, and then enters the main curing stage. By increasing the light intensity, the densification of the cross-linked network structure is ensured, thereby improving the mechanical properties and scratch resistance of the cured film layer, and avoiding the problem of incomplete surface interface structure or interruption of additive migration due to too fast a polymerization rate. In addition, by subjecting the cured film layer to a medium-temperature heat treatment within the range of 60°C-90°C, it helps to further drive the residual functional groups to undergo supplementary reactions, enhance the interlayer bonding strength, and effectively remove low-molecular volatile components, thereby releasing the stress within the system, improving the network structure of the film layer, and reducing the risk of failure such as bubbling and delamination caused by internal stress accumulation or interface unevenness, ensuring that the formed transparent cover layer has excellent structural stability and long-term service performance.

[0073] In step S100, the components are stirred and mixed within a temperature range of 25°C to 35°C to ensure their full dissolution or uniform dispersion in the system, thereby forming a stable coating solution. This temperature range helps prevent premature prepolymerization or localized precipitation of low-volatility active components in the system, ensuring good film-forming uniformity and component compatibility, providing a stable physical and chemical foundation for subsequent film formation and curing steps.

[0074] In step S200, the coating method can be scraping, roller coating, screen printing or spraying, preferably scraping or roller coating, to ensure the uniformity of the wet film thickness and the controllability of the interface quality. Dipping, casting and other methods cannot be selected. The wet film thickness can be, for example, 20μm, 40μm, 60μm, 80μm or 100μm, or any other value between 20μm and 100μm. If the wet film thickness is less than 20μm, it will result in incomplete coverage of the pattern printing layer, affecting the overall decorative effect and subsequent protective performance. If the wet film thickness exceeds 100μm, the stress accumulation in the film layer is too large, causing failure problems such as cracking, loss of gloss or decreased adhesion of the film layer after curing. Therefore, controlling the wet film thickness within the above range helps to achieve a good balance between film quality and mechanical properties while ensuring sufficient coverage.

[0075] The resting temperature can be, for example, 25°C, 30°C, 35°C, or 40°C, or any other value between 25°C and 40°C. The resting time can be, for example, 30 seconds, 50 seconds, 80 seconds, 100 seconds, 130 seconds, 150 seconds, or 180 seconds, or any other value between 30 seconds and 180 seconds. This resting period helps the low-surface-energy additive to spontaneously migrate and accumulate along the concentration gradient before cross-linking occurs. Appropriate resting temperature and time can effectively avoid insufficient additive migration caused by excessively high temperatures or insufficient resting time.

[0076] In one embodiment, before step S200, the following step is further included: performing a surface polarity activation treatment on the pattern printing layer to introduce polar groups on the surface of the pattern printing layer. The surface polarity activation treatment preferably adopts an ultraviolet / ozone treatment method, which generates active oxygen species (such as O3, O 2- , •OH, etc.) act on the surface of the pattern printing layer, and introduce polar groups such as carboxyl and hydroxyl without destroying the integrity of the original pattern, which significantly improves the polarity and wettability of the pattern layer surface, thereby enhancing its interface bonding strength with the transparent cover layer and improving the structural stability of the multi-layer composite structure under hot pressing and hot and cold shock conditions.

[0077] In step S300, the first power is set to 20 mW / cm 2 -100mW / cm 2 , for example, it can be 20mW / cm 2 , 40mW / cm 2 、60mW / cm 2 、80mW / cm 2 or 100mW / cm 2 The irradiation time at the first power is 3s-10s, for example, 3s, 5s or 10s. The second power is set to 200mW / cm2 -800mW / cm 2 , for example, 200 mW / cm 2 , 400mW / cm 2 , 600mW / cm 2 or 800mW / cm 2 The irradiation time at the second power is 10s-30s, for example, 10s, 20s, or 30s. During the pre-curing and curing processes, the film temperature is controlled to not exceed 50°C. This control can achieve sufficient migration of the surface energy additive, dense construction of the cross-linking network, and improved interfacial bonding stability.

[0078] In step S400 , the heating temperature is 60° C. to 90° C., for example, 60° C., 70° C., 80° C., or 90° C. The heating time is 10 min to 30 min, for example, 10 min, 20 min, or 30 min.

[0079] The following is a detailed description with specific examples and comparative examples.

[0080] Example 1:

[0081] An embodiment of the present invention provides a PPM composite board comprising a patterned printed layer and a transparent overcoat layer formed on the surface of the patterned printed layer. The transparent overcoat layer comprises a base layer and an interface structure layer. The base layer is formed by curing an acrylic resin composition into a film. The acrylic resin composition comprises a bridging-type functionalized acrylic monomer and a multifunctional acrylic monomer. The bridging-type functionalized acrylic monomer is a bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer having a number average molecular weight of 800 g / mol. The preparation method of the bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structural monomer comprises:

[0082] Step S11, under nitrogen protection, a mixed solution of 5 mmol of amino-terminated polydimethylsiloxane, 11 mmol of isophorone diisocyanate, 0.05 mmol of dibutyltin dilaurate, and 30 ml of anhydrous toluene was heated to 60 ° C and stirred for 2 hours to generate an isocyanate-terminated polysiloxane intermediate, wherein the amino-terminated polydimethylsiloxane has a product number of 133779-14-3, purchased from Sigma-Aldrich, the product number of isophorone diisocyanate is 4098-71-9, purchased from Wuhan Kanos Technology Co., Ltd., and the product number of dibutyltin dilaurate is 77-58-7, purchased from Sigma-Aldrich;

[0083] Step S12: adding 5 mmol of 4,4'-biphenyl dimethanol and a trace amount of dibutyltin dilaurate to the reaction system of step S11, and reacting at 70°C for 3 hours to generate a symmetrical structure of polydimethylsiloxane-biphenyl-polydimethylsiloxane, wherein the product number of 4,4'-biphenyl dimethanol is 1667-12-5 and is purchased from Santa Cruz Biotechnology;

[0084] Step S13, after the reaction system in step S12 is cooled to room temperature, 12 mmol of 2-hydroxypropyl methacrylate, 0.2 mmol of 4-dimethylaminopyridine, 10 mmol of triethylamine, and a reaction solvent are added in an ice bath, and the mixture is reacted for 12 hours. After washing with water and drying, the solvent is removed by rotary evaporation to obtain a bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane structure monomer, wherein the product number of 2-hydroxypropyl methacrylate is 16083-81-1, purchased from TCI, the product number of 4-dimethylaminopyridine is 1122-58-3, purchased from Aladdin, and the product number of triethylamine is 121-44-8, purchased from Aladdin. The reaction solvent is dichloromethane or tetrahydrofuran.

[0085] The multifunctional acrylic monomer is trimethylolpropane triacrylate (TMPTA), with a number average molecular weight of approximately 300 g / mol. The product number of TMPTA is 15625-89-5, and it was purchased from Hubei Qianmoshengwu Technology Co., Ltd.

[0086] The mass ratio of the bridge-type functional acrylic monomer to the multifunctional acrylic monomer is 1:1.5.

[0087] The interface structure layer is formed in situ on the surface of the substrate layer, and is formed by the migration and accumulation of a low surface energy additive to the surface during the curing reaction. The low surface energy additive is a fluorine-silicon copolymer amphiphilic block polymer. The preparation method of the fluorine-silicon copolymer amphiphilic block polymer includes the following steps:

[0088] 1) Weigh aminopropyl-terminated polydimethylsiloxane (NH2-PDMS-NH2) and hydroxyl-terminated polypropylene oxide (HO-PEO-OH) in a mass ratio of 1.5:1. The aminopropyl-terminated polydimethylsiloxane is purchased from Chengdu McCarthy Chemical Co., Ltd. with the product number 99904-16-2. The hydroxyl-terminated polypropylene oxide is purchased from TCI with the product number 25322-69-4, PEG-1000.

[0089] 2) Aminopropyl-terminated polydimethylsiloxane (NH2-PDMS-NH2) was reacted with isophorone diisocyanate under inert gas protection at 60°C for 1.5 hours to generate an isocyanate-terminated intermediate;

[0090] 3) Introducing hydroxyl-terminated polypropylene oxide into the intermediate and continuing the reaction at 60° for 3 h to form a block structure monomer whose main chain contains Si-O-Si hydrophobic segments and polyether chain-philic segments;

[0091] 4) The above product was co-reacted with 2-hydroxypropyl acrylate in the presence of dibutyltin dilaurate at 60°C for 2 h to introduce terminal acrylate functional groups to obtain a fluorosilicone copolymer amphiphilic block polymer. 2-Hydroxypropyl acrylate was purchased from TCI with a product number of 25584-83-2.

[0092] The fluorosilicone copolymer amphiphilic block polymer is an acrylate-terminated PDMS-b-PEO-b-PDMS amphiphilic block polymer with the structural formula CH2=CH-COO-CH2-CHOH-[PEO]-NH-CO-NH-R 1 -(PDMS)-R 1 -NH-CO-NH-[PEO]-CH2-CHOH-COO-CH=CH2. Among them, R 1 represents the residue of isophorone diisocyanate, PDMS represents a polydimethylsiloxane segment, which belongs to the Si-O-Si segment, [PEO] represents a polypropylene oxide segment, and CH2=CH-COO- represents a terminal acrylate group.

[0093] The transparent cover layer includes the following components in parts by weight: 60 parts of an acrylic resin composition, 25 parts of a reactive diluent monomer, 2 parts of a low surface energy additive, 2 parts of a photoinitiator, 1 part of a light stabilizer, 1 part of a polar monomer, 3 parts of a leveling agent, 1 part of an antioxidant and 0.2 parts of an inhibitor.

[0094] Reactive diluent monomers, leveling agents, antioxidants, and polymerization inhibitors are all conventional additives known to those skilled in the art. For example, the reactive diluent monomer may be hexanediol diacrylate, tripropoxy acrylate, trimethylolpropane triacrylate, or polyethylene glycol diacrylate. The leveling agent may be a polyether-modified silicone oil additive such as BYK-333. The antioxidant may be a hindered phenol antioxidant such as Irganox 1010. The polymerization inhibitor may be hydroquinone or p-methoxyphenol (MEHQ).

[0095] The present invention also provides a method for preparing the aforementioned PPM composite board, which comprises:

[0096] Step 1: stirring and mixing the components in the transparent overcoat layer at room temperature to obtain a coating liquid;

[0097] Step 2: Apply the coating liquid to the surface of the pattern printing layer after the surface polarity activation treatment by knife coating to form a wet film with a thickness of about 30 μm, and let it stand at 25° C. for 60 seconds;

[0098] Step 3: wet film at 40mW / cm 2 Pre-curing was performed under a high power UV light source for 5 seconds, and then at 400mW / cm 2 Perform main curing treatment under a high-power ultraviolet light source for 20 seconds to form a cured film layer;

[0099] Step 4: heating the cured film layer at 80° C. for 10 minutes to obtain a transparent overcoat layer.

[0100] Example 2:

[0101] The only difference between this embodiment and Example 1 is that the bridged functionalized acrylic monomer is a bis(methacrylate)-terminated polydimethylsiloxane-triphenylmethane monomer. The preparation method for this bis(methacrylate)-terminated polydimethylsiloxane-triphenylmethane monomer is the same as the preparation method for the bis(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer in Example 1, with the exception that in step S12, 4,4'-biphenyl dimethanol is replaced with p-phenylenediol. This p-phenylenediol is available from Sigma-Aldrich under the product number 589-29-7.

[0102] The multifunctional acrylic monomer is pentaerythritol tetraacrylate, the product number of which is 4986-89-4 and is purchased from TCI. The low surface energy additive is Silmer ACR Di-50, a polyether-modified silicone acrylate block polymer.

[0103] Comparative Example 1:

[0104] The only difference between this comparative example and Example 1 is that the acrylic resin composition does not contain a bridged functional acrylic monomer and consists only of a multifunctional acrylic monomer.

[0105] Comparative Example 2:

[0106] The only difference between this comparative example and Example 1 is that the acrylic resin composition does not contain a multifunctional acrylic monomer and only consists of a bridge-type functionalized acrylic monomer.

[0107] Comparative Example 3:

[0108] This comparative example differs only from Example 1 in that the aromatic ring bridging group in the bridged-functional acrylic monomer is replaced with hexanediol. Specifically, the bridged-functional acrylic monomer is replaced with a bis(methacryloxypropyl)-terminated polydimethylsiloxane-hexanediol-polydimethylsiloxane monomer. The preparation method for this bis(methacryloxypropyl)-terminated polydimethylsiloxane-hexanediol-polydimethylsiloxane monomer is consistent with the preparation method for the bis(methacryloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer in Example 1, except that in step S12, 4,4'-biphenyl dimethanol is replaced with 1,6-hexanediol, the product number of which is 629-11-8.

[0109] Comparative Example 4:

[0110] The only difference between this comparative example and Example 1 is that the methacryloyloxypropyl group in the bridged-functional acrylic monomer is replaced with a hydroxyl group. Specifically, the bridged-functional acrylic monomer is replaced with a dihydroxy-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer. The preparation method for the dihydroxy-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer differs from the preparation method for the di(methacryloyloxypropyl)-terminated polydimethylsiloxane-biphenyl-polydimethylsiloxane monomer in Example 1 in that the preparation method in this comparative example does not include step S13 of Example 1; all other steps remain the same.

[0111] Comparative Example 5:

[0112] This comparative example differs only from Example 1 in that the polydimethylsiloxane segment in the bridged-functional acrylic monomer is replaced with a polyethylene oxide segment. Specifically, the bridged-functional acrylic monomer is replaced with a bis(methacryloxypropyl)-terminated polyethylene oxide-biphenyl-polyethylene oxide monomer. The preparation method for this bis(methacryloxypropyl)-terminated polyethylene oxide-biphenyl-polyethylene oxide monomer differs only in step S11. In this comparative example, the amino-terminated polydimethylsiloxane in step S11 of Example 1 is replaced with amino-terminated polyethylene oxide. This amino-terminated polyethylene oxide is purchased from TCI with product number 24991-53-5.

[0113] Comparative Example 6:

[0114] This comparative example differs from Example 1 only in that the low-surface-energy additive is a PDMS-b-PEO-b-PDMS amphiphilic block polymer without terminal acrylate functional groups, i.e., its terminals do not contain polymeric groups capable of undergoing free radical crosslinking reactions with the acrylic resin composition. The preparation method for the fluorosilicone copolymer amphiphilic block polymer in Comparative Example 6 differs from that in Example 1 only in that this comparative example does not include step 3 of Example 1.

[0115] Comparative Example 7:

[0116] The only difference between this comparative example and Example 1 is that in this comparative example, the low surface energy additive is PEO-b-PPO-b-PEO triblock polyether, which does not contain Si-O-Si and (CF2) n The hydrophobic segments were not introduced, and no photo-crosslinkable acrylate end groups were introduced. The PEO-b-PPO-b-PEO triblock polyether was Pluronic® F127, purchased from Sigma-Aldrich.

[0117] Comparative Example 8:

[0118] The only difference between this comparative example and Example 1 is that the mass ratio of the bridge-type functionalized acrylic monomer to the multifunctional acrylic monomer is 2:1.

[0119] The following is a performance comparison table of each embodiment and comparative example, as shown in Table 1.

[0120]

[0121] In Table 1 above, hardness is tested according to GB / T 6739-2006 (pencil hardness method). Using a 6B-9H standard hardness pencil, the film is scratched at a fixed angle and load. The highest hardness grade that does not produce a scratch is recorded, reflecting the mechanical scratch resistance of the overcoat. Adhesion refers to the adhesion between the transparent overcoat and the pattern printed layer. Adhesion is assessed according to GB / T 9286-2021 (paint film cross-cut test method). Adhesion is graded using a standard cross-cut and tape peeling method, with 5B being the highest, indicating no peeling. Transmittance is used to evaluate the optical performance of the transparent overcoat. This optical performance reflects pattern visibility and clarity, film density and compatibility, and indirectly reflects the uniformity of the cross-linked network. Transmittance is measured using an ultraviolet-visible spectrophotometer (UV-Vis) at 550nm. Total transmittance is calculated by averaging data from multiple measurement points according to GB / T 2410-2008. Scratch resistance was tested using a modified load scratch method according to ASTM D7027-20. The minimum load (in grams) at which visible scratches began to appear was recorded, reflecting the film's resistance to damage. Water contact angle was measured according to GB / T 30693-2014, using a contact angle analyzer to measure the static contact angle of a 3μL water droplet on the film at room temperature. This was used to evaluate the hydrophobicity and anti-fingerprint properties of the transparent overcoat layer. Cracking / warping after thermal shock was tested according to GB / T 2423.22-2012. The test sample was subjected to repeated thermal shock cycles between -30°C and 85°C (at least 20 times) to observe whether the film exhibited structural defects such as cracking, warping, and delamination. This verified the thermal stress buffering capacity and interfacial stability of the transparent overcoat layer. UV aging is tested using a UV aging chamber in accordance with ASTM G154-16. The yellowing index (ΔYI) of the film before and after coating is calculated in conjunction with ASTM E313-20. A lower ΔYI indicates better anti-yellowing performance. The fingerprint resistance index is based on company standards. The film surface is coated with artificial sebum or standard fingerprint oil, and after drying, image analysis and a visible residue rating system are used to assess the resistance. The index is graded from 1 to 10, with higher indexes indicating less resistance to fingerprint residue.

[0122] As can be seen from Table 1, Example 1 of the present invention exhibits excellent characteristics in terms of comprehensive film performance, with a hardness of 3H, a scratch resistance of 750g, and a transmittance of 92.5%, indicating that the cured film has good surface strength, density, and optical transparency. In particular, no cracks or warping were observed after the hot and cold shock test, and the adhesion remained at the highest level (5B). This fully demonstrates that the three-dimensional cross-linked network structure constructed by synergistically introducing a bridge-type functionalized acrylic monomer with an aromatic ring bridging group and a multifunctional acrylic monomer in the embodiment of the present invention not only ensures the curing strength and interfacial bonding strength of the film, but also has the ability to alleviate stress concentration caused by thermal expansion mismatch. At the same time, the water contact angle is 105° and the fingerprint resistance index is 10, indicating that the embodiment of the present invention, by introducing a polymerizable low-surface energy additive, can form a stable surface interface structure layer during the film curing process, giving the film excellent anti-fouling and anti-fingerprint properties. Furthermore, the yellowing index change ΔYI was 1.2, significantly lower than all comparative examples, indicating that it maintained good optical stability and yellowing resistance under UV-accelerated aging conditions. This is attributed to the absence of yellowing-prone components in the formulation and the π-conjugated system in the aromatic ring bridge structure, which effectively absorbs and dissipates UV radiation energy, enhancing the material's resistance to UV radiation-induced degradation and inhibiting yellowing and performance degradation of the film. Example 2 is similar to Example 1.

[0123] In the comparative example 1, no bridging functionalized acrylic monomer was introduced, and only multifunctional acrylic monomer was used to construct a cross-linked network. Although a rigid structure with a higher cross-linking density was formed, the lack of flexible segment regulation resulted in insufficient overall toughness. After the hot and cold shock test, obvious cracks appeared in the film layer, the scratch resistance dropped significantly to 520g, the transmittance dropped to 82.6%, the water contact angle dropped to 78°, and the fingerprint resistance index dropped to 6, indicating that the performance of the film layer deteriorated significantly under the condition of rigid-flexible structure imbalance. In addition, due to the lack of flexible buffering and conformational regulation in the cross-linked network, the internal stress release is limited, and microcracks and stress concentration are easily generated during curing and use, resulting in a decrease in the integrity of the film layer structure. Therefore, despite its high degree of cross-linking, the apparent hardness is only 2H and the adhesion is reduced to 3B, reflecting that the film layer density and interface stability are both damaged. This result verifies that in a high-rigidity cross-linked structure, if there is a lack of a flexible bridging regulation mechanism, structural instability and multi-performance degradation are easily caused.

[0124] In Comparative Example 2, no multifunctional acrylic monomer was introduced, and only bridging-type functionalized acrylic monomers were used to construct a cross-linked network. Although the bridging-type monomer contains flexible segments, which helps to alleviate interfacial stress to a certain extent, due to its low functionality, the overall cross-linking density is insufficient, and the formed cured film structure is loose and has poor density. In terms of specific performance, the scratch resistance of the film layer dropped to 450g, the adhesion dropped to 4B, and slight cracks appeared in the hot and cold shock test, indicating that its mechanical strength and structural stability are difficult to meet the dual requirements of stress release and interface bonding of the multilayer composite material. In addition, the transmittance, water contact angle, fingerprint resistance and yellowing inhibition ability also showed varying degrees of decline, indicating that it is difficult to achieve a balanced improvement in the comprehensive performance of the film layer by relying solely on bridging-type functionalized monomers to construct a cross-linked structure. This result further verifies that the synergistic effect of bridging-type and multifunctional acrylic monomers plays a key role in constructing a rigid-flexible, dense and stable three-dimensional cross-linked network structure, and neither of them can be missing.

[0125] In Comparative Examples 3 through 5, replacing the aromatic ring bridging group with hexanediol (a linear aliphatic segment), removing the terminal polymerizable group, or replacing PDMS with PEG segments, respectively, all resulted in unstable interfacial bonding in the film, leading to warping, cracking, or peeling after thermal shock. Furthermore, scratch resistance, adhesion, contact angle, and aging ΔYI all significantly decreased, demonstrating that the aromatic ring rigidity of the bridging structure and the flexible siloxane segments are both essential and synergistic, contributing to the film's overall performance.

[0126] Comparative Examples 6 and 7 respectively remove the reactive groups or Si-O / CF segments in the low surface energy additive, resulting in a deterioration in the interfacial energy adjustment ability, verifying the criticality of this type of block structure in interface positioning and anti-fouling adjustment.

[0127] In comparative example eight, the ratio of bridging-type to multifunctional monomers was adjusted to 2:1. Although the hardness remained at 3H, cracks still appeared after hot and cold shock, and the scratch resistance decreased, indicating that the ratio deviated from the optimal ratio, resulting in high structural flexibility and unbalanced mechanical properties.

[0128] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A printed pattern decorative polymer composite board, characterized in that: It includes a pattern printing layer and a transparent cover layer formed on the surface of the pattern printing layer, and the transparent cover layer includes: The base layer is formed by curing an acrylic resin composition to form a film, wherein the acrylic resin composition comprises at least one bridge-type functional acrylic monomer and at least one multifunctional acrylic monomer, wherein the general formula of the bridge-type functional acrylic monomer is R1-[SiO] n -Ph-[SiO] m -R2, wherein R1 and R2 are acrylate groups, n and m are integers of 2-10, [SiO] is a siloxane segment, Ph is an aromatic ring bridging group, the molecular structure of the multifunctional acrylic monomer has three or more acrylate groups, and the mass ratio of the bridging functional acrylic monomer to the multifunctional acrylic monomer is 1:(1.5-2); The interface structure layer is formed in situ on the surface of the substrate layer and is formed by the migration and accumulation of the low surface energy additive to the surface during the curing reaction; The low surface energy additive contains Si-O-Si and / or (CF2) in the main chain n An amphiphilic block polymer having a hydrophobic segment, the terminal or side chain of which contains a functional group capable of undergoing a cross-linking reaction with the acrylic resin composition; The transparent overcoat layer comprises the following components in parts by weight: 50-90 parts of an acrylic resin composition, 0.5-5 parts of a low surface energy additive, 0.5-3 parts of a photoinitiator, 0.3-2 parts of a light stabilizer and 0.1-3 parts of a polar monomer.

2. The printed pattern decorative polymer composite board according to claim 1, characterized in that: The number average molecular weight of the bridge-type functionalized acrylic monomer is 400 g / mol-1500 g / mol, and the number average molecular weight of the multifunctional acrylic monomer is 200 g / mol-1000 g / mol; The functional group molar ratio of the bridge-type functional acrylic monomer to the multifunctional acrylic monomer is (0.8-1.5):

1.

3. The printed pattern decorative polymer composite board according to claim 2, characterized in that: The aromatic ring bridging group is a diphenyl group, a biphenyl group, a triphenylmethane group or a fluorenyl group structure.

4. The printed pattern decorative polymer composite board according to claim 3, characterized in that: The mass ratio of the hydrophobic segment and the resin-philic segment in the low surface energy additive is (1-2): 1; The number average molecular weight of the amphiphilic block polymer is 800 g / mol-5000 g / mol.

5. The printed pattern decorative polymer composite board according to claim 4, characterized in that: The mass fraction of the Si-O-Si hydrophobic segment in the amphiphilic block polymer is 5wt%-15wt%, and the (CF2) n The mass fraction of the hydrophobic segment in the amphiphilic block polymer is 2wt%-10wt%.

6. The printed pattern decorative polymer composite board according to claim 5, characterized in that: The polar monomer is an acrylate monomer containing a carboxyl group, a hydroxyl group, an amide group or a sulfonate structure; The photoinitiator is a combination of one or more of α-hydroxy ketones, alkyl phenones, phosphorus oxides and phenyl diketones; The light stabilizer is a combination of one or more of an ultraviolet absorber, a hindered amine light stabilizer and an organic phosphate antioxidant.

7. A method for preparing a printed pattern decorative polymer composite board according to any one of claims 1 to 6, characterized in that: The steps include: uniformly mixing the components in the transparent overcoat layer to obtain a coating liquid; Applying the coating liquid on the surface of the pattern printing layer to form a wet film with a thickness of 20 μm-100 μm, and standing at 25° C.-40° C. for 30 seconds-180 seconds; Performing a pre-curing treatment on the wet film under a first power ultraviolet light source, and then performing a main curing treatment under a second power ultraviolet light source to form a cured film layer; The cured film layer is heated at 60° C.-90° C. for 10 min-30 min to obtain the transparent overcoat layer.

8. The preparation method according to claim 7, characterized in that Before coating the coating liquid on the surface of the pattern printing layer, the following steps are also included: The pattern printing layer is subjected to surface polarity activation treatment to introduce polar groups onto the surface of the pattern printing layer.

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