Preparation process of mildly peelable composite material

Abstract

The invention discloses a preparation process of a mildly peelable composite material, which comprises the following steps: preparing first slurry: mixing structural resin based on polyvinyl acetal resin, adhesive resin containing phenolic resin and epoxy resin, and a high-performance organic polymer with a main chain containing aromatic rings and / or heterocyclic rings in a first solvent, filtering to obtain the first slurry; preparing a second slurry, namely mixing an inorganic filler of which the surface is modified by at least one functional group selected from a group consisting of anilino, a nitrogen-containing functional group on a main chain or a branched chain, a double-bond-containing functional group and an epoxy group in a second solvent to obtain the second slurry; and mixing: mixing the second slurry with the first slurry to obtain mildly peelable mixed slurry. The preparation process has the advantages of improving the reliability and stability of the protective performance of the protective material, widening the process window, reducing the rejection rate of production and the like.

Description

Technical Field

[0001] The invention relates to the technical field of printed circuit board manufacturing, and in particular to a preparation process of a gently peelable composite material. Background Art

[0002] In the manufacturing of printed circuit boards (PCBs) and flexible circuit boards (FPCs), temporary protective materials, such as protective inks and dry films, are essential for ensuring the success of key processes such as electroless copper plating, etching, and multilayer lamination. As electronic technology continues to evolve toward higher density and performance, manufacturing processes are becoming increasingly demanding, such as the use of more corrosive chemicals and higher lamination temperatures and pressures. This has resulted in traditional temporary protective materials becoming increasingly inadequate in terms of protective performance, making it difficult to meet the manufacturing requirements of the next generation of products.

[0003] To meet this challenge, the industry has begun to conceive of developing new composite protective materials. Such materials not only need to have excellent chemical resistance, heat resistance, and pressure resistance to withstand harsh preparation environments; at the same time, in order to adapt to the application of sensitive substrates such as glass and ceramics and protect increasingly sophisticated circuits, they must also have a key characteristic - the ability to be easily and completely stripped off with mild and non-destructive solvents after protection is completed. However, these two goals are contradictory in materials science: high protection usually means that the material has a stable and dense chemical cross-linked network, and this structure itself is difficult to be destroyed by mild solvents. Therefore, developing an innovative material that can successfully balance this inherent contradiction has become a technical problem that needs to be solved urgently in this field.

[0004] However, even if such a complex formula containing multiple functional components is designed, transforming it from theory to an actual product with stable performance and no defects still faces huge challenges in the preparation process. It is extremely difficult to evenly mix these components with very different chemical properties and physical forms. In particular, inorganic fillers are very easy to agglomerate in the viscous resin, forming defect points. At the same time, the thermosetting components in the system are very sensitive to heat and shear forces during the mixing process, and are very likely to pre-cure and cause the entire batch of materials to be scrapped. Therefore, this field not only needs an advanced material formula, but also urgently needs a specific and controllable preparation process to solve the problem of uniform dispersion and stable preparation of the above-mentioned multi-component complex system, so as to turn this advanced material with both high protection and mild strippability from concept into reality. Summary of the Invention

[0005] The main purpose of the present invention is to propose a preparation process for a composite material that can be gently peeled, aiming to solve the technical difficulties faced in preparing advanced composite materials containing multiple components with different chemical properties, such as the difficulty in uniformly dispersing the components and the poor process stability.

[0006] To achieve the above-mentioned purpose, the present invention provides a process for preparing a composite material that can be gently peeled.

[0007] Preparing a first slurry: mixing a structural resin based on a polyvinyl acetal resin, a binder resin comprising a phenolic resin and an epoxy resin, and a high-performance organic polymer having an aromatic ring and / or a heterocyclic ring in a main chain in a first solvent to obtain the first slurry;

[0008] Preparing a second slurry: mixing an inorganic filler whose surface is modified with at least one functional group selected from the group consisting of aniline groups, nitrogen-containing functional groups on the main chain or side chains, double bond-containing functional groups, and epoxy groups in a second solvent to obtain the second slurry; and

[0009] Mixing: Mixing the second slurry with the first slurry to obtain a mixed slurry that can be gently peeled.

[0010] In one embodiment, the mixing conditions for mixing the structural resin, the binder resin, and the high-performance organic polymer in the first solvent and the inorganic filler in the second solvent include:

[0011] The mixing speed is between 3600 rpm and 7200 rpm;

[0012] The temperature of the mixed slurry is not higher than 45℃;

[0013] The mixing time ranged from 60 minutes to 120 minutes.

[0014] In one embodiment, the step of preparing the first slurry further comprises: pre-dissolving or dispersing a dispersant and / or a defoaming agent in the first solvent before adding the structural resin, the binder resin, and the high-performance organic polymer to the first solvent; and

[0015] The step of preparing the second slurry further includes: pre-dissolving or dispersing a dispersant and / or a defoaming agent in the second solvent before adding the inorganic filler into the second solvent.

[0016] In one embodiment, the first solvent and / or the second solvent comprises at least one of the following substances:

[0017] Ethanol, acetone, butanone, cyclohexanone, toluene, xylene.

[0018] In one embodiment, the steps of preparing the mixed slurry include:

[0019] Slowly adding the second slurry to the stirred first slurry;

[0020] After the addition of the second slurry is completed, mixing is continued for 60 minutes to 120 minutes; and

[0021] During the mixing process, the temperature of the mixed slurry was kept below 45°C.

[0022] In one embodiment, after obtaining the mixed slurry, the preparation process further comprises:

[0023] Film formation: The mixed slurry is coated on a substrate film and dried at a temperature of 50° C. to 120° C. for 3 to 10 minutes.

[0024] In one embodiment, the polyvinyl acetal resin is polyvinyl butyral resin.

[0025] In one embodiment, the high-performance organic polymer is at least one selected from polyimide, poly(p-phenylene benzobisoxazole), polybenzimidazole, benzoxazine, bismaleimide, and bismaleimide triazine.

[0026] In one embodiment, the inorganic filler is selected from at least one of graphite, carbon black, graphene, silicon dioxide, aluminum oxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, magnesium silicate, silicon carbide, titanium carbide, titanium oxide, magnesium oxide, calcium oxide, boron nitride, and aluminum nitride.

[0027] In one embodiment, the components of the mixed slurry are as follows:

[0028] The weight percentage of the structural resin is between 40% and 90%;

[0029] The weight percentage of the bonding resin is between 5% and 40%;

[0030] The weight percentage of the high performance organic polymer is between 5% and 50%;

[0031] The weight percentage of the inorganic filler is between 0.5% and 40%.

[0032] The preparation process of this application adopts the core concept of step-by-step pulping. By separating the pre-dispersion steps of the chemically distinct organic phase components (in the first slurry) and the inorganic phase components (in the second slurry), it is possible to focus and efficiently de-agglomerate the most difficult-to-disperse inorganic fillers, avoiding the agglomeration problem that inevitably occurs when they are directly mixed in a viscous polymer system. This enables the preparation of a mixed slurry with extremely uniform inorganic filler dispersion, thereby ensuring that the protective material that is ultimately cured into a film has a dense, uniform, and defect-free microstructure, greatly improving the reliability and stability of its protective performance.

[0033] At the same time, by precisely controlling key physical parameters during the mixing process (such as rotational speed and temperature), particularly high-shear mixing at low temperatures, the premature gelation of the thermosetting resins (phenolic and epoxy resins) in the system, which can occur due to heat generation during high-intensity mechanical stirring, is effectively suppressed. This significantly widens the process window, reduces production scrap rates, and enables industrialized, large-scale production of this complex formulation, ensuring consistent performance across batches.

[0034] Furthermore, because the preparation process of this application overcomes the aforementioned production issues, the composite material prepared using this process, due to its uniform and dense internal structure, can reliably withstand chemical attack from strong acids and bases, as well as physical impact from high temperatures and high pressures. Furthermore, the uniform dispersion maximizes the effectiveness of the adhesive resin and functional filler, ensuring a secure bond between the material and the substrate and excellent surface hardness. Furthermore, this process ensures that the polyvinyl acetal resin, serving as the strippable matrix, forms a complete, continuous network, enabling gentle solvent stripping. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0036] Figure 1 This is a flow chart of an embodiment of a process for preparing a gently peelable composite material according to the present invention;

[0037] Figure 2 The flowchart is another embodiment of the preparation process of the gently peelable composite material of the present invention.

[0038] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing in the full text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution in which both A and B are satisfied. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0042] This invention proposes a process for preparing a gently peelable composite material, employing a stepwise slurry preparation and mixing process to produce a composite material suitable for copper process protection on printed circuit boards (PCBs) or flexible circuit boards (FPCs). The composite material comprises a structural resin based on polyvinyl acetal resin, a binder resin comprising phenolic resin and epoxy resin, and chemical-resistant additives (including a high-performance organic polymer with aromatic or heterocyclic rings in the backbone and a surface-modified inorganic filler). The composite material is resistant to strong acids and alkalis (such as sulfuric acid and sodium hydroxide), high temperatures and high pressures (such as 180°C and 1.8 MPa), and can be peeled off after the process is completed using a mild solvent (such as a mixture of ethanol and water) without damaging the substrate (such as glass or ceramic).

[0043] In one embodiment of the present invention, the structural resin is based on a structural resin of a polyvinyl acetal resin. The structural resin is mainly used as a film-forming substance in the composite material to form a continuous polymer matrix. It not only provides a carrier for other functional components, but more importantly, it lays the technical foundation for the entire composite material to be gently peeled off. This is because polyvinyl acetal resins (especially polyvinyl butyral resins) have good solubility or swelling properties in specific mild organic solvents such as alcohols. When the protective film needs to be removed, the solvent can be used to selectively destroy or dissolve the structural resin matrix as the continuous phase, thereby causing the entire film layer structure to disintegrate and achieve easy peeling.

[0044] Optionally, the weight percentage of the structural resin in the composite material is between 40% and 90%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%.

[0045] Specifically, when the content of the structural resin is no less than 40%, the amount of structural resin is sufficient to form a complete, continuous polymer network, thereby effectively encapsulating and bonding other functional components (binder resin, chemical resistance additives) together to form a uniform, defect-free protective film. If its content is less than 40%, it may lead to poor film formation, film defects, or the inability to form a continuous matrix, making it impossible to effectively dissolve the matrix during peeling.

[0046] When the structural resin content is no higher than 90%, sufficient space is left for other protective components, avoiding dilution of the overall material's chemical resistance, heat resistance, and mechanical strength due to excessive structural resin content, thereby ensuring the material's ability to protect in harsh environments. Conversely, if it exceeds 90%, the material's overall protective performance (chemical resistance, heat resistance, and mechanical strength) will be greatly compromised, making it difficult to meet actual application requirements.

[0047] Furthermore, the adhesive resin ensures that the composite material adheres firmly to various substrates, such as copper foil, epoxy resin, or glass, after curing. It also increases the composite material's crosslinking density, enhancing its pressure, heat, and chemical resistance, preventing it from cracking or falling apart even in demanding processes like high temperature and high pressure. This is because the adhesive resin undergoes a cross-linking reaction during the curing process, forming a strong chemical bond that strengthens adhesion to the substrate while also increasing the overall composite material's cohesive strength, hardness, and heat resistance.

[0048] Specifically, the bonding resin includes phenolic resin and epoxy resin. Epoxy and phenolic resins can be used in the form of pure substances, mixtures, or compounds of the following materials:

[0049] The epoxy resin material used in this application has an epoxy molecular weight of 2500 g / mol to 6000 g / mol:

[0050] (1) Glycidylamine epoxy resin

[0051] Structural formula:

[0052] The epoxy equivalent is between 93 and 150 g / eq, the hydrolyzed chlorine should be less than 200 ppm, and the viscosity at 25°C is between 0.5 and 5 Poise.

[0053] (2) Multifunctional o-cresol aldehyde glycidyl ether type epoxy resin

[0054] Structural formula:

[0055] The epoxy equivalent is between 195 and 230 g / eq, the hydrolyzed chlorine at 120°C is between 470 and 1000 g / eq, the ICI viscosity at 150°C is between 0.9 and 60 Poise, and the softening point is between 45 and 96°C.

[0056] (3) Phenol biphenyl epoxy resin

[0057] Structural formula:

[0058] The epoxy equivalent weight is between 261 and 280 g / eq, the hydrolyzed chlorine content should be less than 100 ppm, the viscosity at 25°C is between 0.1 and 4.5 Poise, and the softening point is 45 to 75°C. Adding it to PVB and its hydroxyl copolymer can effectively improve the glass strength, Tg, and impact resistance of copper.

[0059] (4) Bisphenol F solid epoxy resin

[0060] Structural formula:

[0061] The epoxy equivalent is between 450 and 1000 g / eq, the hydrolyzed chlorine should be less than 300 ppm, the viscosity at 25°C is less than 1000 Poise, and the softening point is 50 to 88°C.

[0062] Solid bisphenol F epoxy resin is characterized by low viscosity and flexibility. The performance of its cured product is almost the same as that of bisphenol A epoxy resin. Adding it to PVB and copolymerizing it with its hydroxyl group can effectively improve its corrosion resistance.

[0063] (5) Isocyanate (MDI) modified epoxy resin

[0064] Structural formula:

[0065] The epoxy equivalent is between 280 and 380 g / eq, the hydrolyzed chlorine should be less than 300 ppm, the viscosity at 25°C is between 0.5 and 3 Poise, and the softening point is 50 to 88°C.

[0066] Solid bisphenol F epoxy resin is characterized by low viscosity and flexibility. The performance of its cured product is almost the same as that of bisphenol A epoxy resin. Adding it to PVB and copolymerizing it with its hydroxyl group can effectively improve the bonding strength and peel strength.

[0067] (6) Naphthol-type epoxy resin

[0068] Structural formula:

[0069] The epoxy equivalent is between 280 and 380 g / eq, the hydrolyzed chlorine should be less than 300 ppm, the viscosity at 25°C is between 0.5 and 3 Poise, and the softening point is 50 to 88°C.

[0070] Its curing properties, heat resistance and mechanical properties are superior to those of traditional bisphenol A. Due to its low internal stress, high Tg and high adhesion performance, it can be added to PVB and its hydroxyl copolymer to effectively improve the Tg point, bonding strength and peel strength.

[0071] (7) Phenol novolac epoxy resin

[0072] Structural formula:

[0073] The epoxy equivalent weight is between 165 and 200 g / eq, the hydrolyzed chlorine content should be less than 250 ppm, the viscosity at 25°C is between 1.1 and 12.5 Poise, and the softening point is 25 to 86°C. Because it contains two or more epoxy groups in its molecular structure, it can be added to PVB and copolymerized with its hydroxyl groups to achieve a high crosslink density, resulting in excellent bonding strength, heat resistance, and chemical resistance. Because it contains two or more epoxy groups in its molecular structure, the cured product has a high crosslink density, resulting in excellent bonding strength, heat resistance, and chemical resistance. While standard PVB is compatible with low-molecular-weight epoxy resins, high-molecular-weight epoxy resins require PVB with a high acetalization degree for compatibility.

[0074] Furthermore, the phenolic resin material used in this application is mainly used as a curing agent and can be a pure substance, mixture or compound of the following materials:

[0075] (1) Linear phenol formaldehyde resin

[0076] Structural formula:

[0077] The free phenol content is less than 0.6%, the softening point is 96-123°C, the hydroxyl equivalent is between 105-119 g / eq, and the conductivity is less than 8 us / cm.

[0078] (2) Linear BPA formaldehyde resin

[0079] Structural formula:

[0080] The free phenol content is 1-45%, the softening point is 90-140°C, the hydroxyl equivalent is between 112-130 g / eq, and the conductivity is less than 20 us / cm.

[0081] Optionally, the weight percentage of the adhesive resin in the protective material is between 5% and 40%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%.

[0082] Specifically, when the binder resin content is no less than 5%, it can form sufficient cross-linking density, providing strong adhesion between the protective film and substrates such as copper foil and glass, preventing it from falling off during chemical immersion or high-pressure washing. At the same time, it also improves the hardness and heat resistance of the film itself.

[0083] When the binder resin content is no higher than 40%, excessive crosslinking can be avoided. Excessive crosslinking can make the film too rigid and brittle. More importantly, it can severely damage the soluble matrix of the structural resin, preventing mild solvents from effectively penetrating and dissolving it, resulting in a loss of mild peelability. Therefore, this content range strikes a critical balance between ensuring adhesion and maintaining the material's peelability.

[0084] Furthermore, the chemical resistance additive is composed of a high performance organic polymer and a surface modified inorganic filler.

[0085] On the one hand, a high-performance organic polymer is a polymer whose main chain contains a large number of aromatic rings and / or heterocyclic structures, where the main chain refers to the longest and most core skeleton chain that constitutes the polymer. Aromatic rings usually refer to highly stable planar ring structures such as benzene rings. Heterocyclic rings refer to rings that contain not only carbon atoms but also other elements such as nitrogen (N) and oxygen (O). The high-performance organic polymer can be composed entirely of aromatic rings or of both aromatic rings and heterocyclic rings.

[0086] Therefore, the presence of aromatic and / or heterocyclic rings in the backbone means that, unlike simple, flexible chains consisting of carbon-carbon single bonds, such as polyethylene, the molecular backbone of these high-performance polymers is composed of a large number of very stable and rigid cyclic structures directly connected in series. This rigid cyclic backbone structure gives it extremely high chemical inertness and thermal stability, making it a strong chemical barrier in composite materials.

[0087] Optionally, the weight percentage of the high performance organic polymer in the protective material is between 5% and 50%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%.

[0088] Specifically, when the content of high-performance organic polymers is not less than 5%, these highly stable polymers can form effective chemical and thermal barriers in the material, significantly improving the material's ability to resist strong acid and alkali corrosion and high temperature.

[0089] When the content of high-performance organic polymers is kept below 50%, the significant cost increases and processing difficulties associated with excessive amounts can be avoided. This also prevents excessive content from disrupting the continuity of the structural resin matrix, which could affect the final film quality and release properties. This range ensures optimal chemical and thermal stability while maintaining controllable costs.

[0090] On the other hand, the surface of the inorganic filler is modified with specific functional groups. The inorganic filler itself acts as a physical barrier, which can effectively improve the mechanical strength, hardness and pressure resistance of the material and increase the penetration path of chemicals. More importantly, the modified functional groups on its surface, such as at least one selected from the group consisting of aniline groups, nitrogen-containing functional groups, double-bond functional groups and epoxy groups, can act as a "bridge" to form an effective physical effect (such as hydrogen bonding) or chemical bonding between the surface of the inorganic filler and the surrounding organic resin matrix. This strong interfacial bonding ensures that the inorganic filler can be stably and evenly dispersed and synergistically work with the matrix to maximize its reinforcing and protective effects.

[0091] In some embodiments, the inorganic filler is selected from at least one of graphite, carbon black, graphene, silicon dioxide, aluminum oxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, magnesium silicate, silicon carbide, titanium carbide, titanium oxide, magnesium oxide, calcium oxide, boron nitride, and aluminum nitride. These fillers can significantly improve the mechanical properties of the composite material (such as hardness, Young's modulus, tensile modulus, and flexural modulus). The addition of graphite, carbon black, and graphene can enhance the solid content and screen printing capabilities of the composite material after film formation.

[0092] Optionally, the weight percentage of the inorganic filler in the protective material is between 0.5% and 40%, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%.

[0093] Specifically, when the content of inorganic filler is not less than 0.5%, the amount of filler is sufficient to form an effective physical reinforcement network in the material, thereby giving the film layer excellent surface hardness and resistance to physical scratches, and improving its pressure resistance in processes such as multilayer board lamination.

[0094] When the inorganic filler content is no higher than 40%, the negative effects caused by excessive filler content (i.e., "overloading") can be avoided, such as high slurry viscosity making it difficult to coat, brittle and cracked films after curing, and decreased adhesion and peelability due to the relative reduction in polymer matrix. This content range is ideal for improving the material's physical protective properties without sacrificing its process suitability and core functionality.

[0095] It can be understood that the technical solution of this application, by using a structural resin based on polyvinyl acetal resin as the material matrix, allows the cured protective film to be quickly and thoroughly stripped using mild solvents such as alcohols that do not damage the substrate after it has completed its mission. This fundamentally avoids the risk of damage to sensitive substrates (such as glass and ceramics) or high-density circuits caused by traditional strong acid and strong base stripping processes.

[0096] At the same time, the bonding resin, which includes phenolic resin and epoxy resin, ensures strong adhesion between the cured protective film and various substrates such as copper surfaces, epoxy substrates, and glass substrates. This effectively prevents the protective film from edge warping, delamination, or shedding during high temperature, high pressure, or chemical immersion processes, ensuring the effectiveness and continuity of protection.

[0097] In addition, by introducing chemical-resistant additives (especially high-performance organic polymers with aromatic and / or heterocyclic rings in the main chain and inorganic fillers with modified surfaces by specific functional groups), the composite material of the present application can effectively resist the corrosion of chemicals such as strong acids and strong alkalis, and can withstand high temperatures (e.g., 180°C) and high pressures (e.g., greater than 1.8 MPa) in processes such as multilayer board lamination, providing all-round and stable protection for fine copper circuits.

[0098] In addition, through the specific content ratio of each component, the protective function and the peeling function can be taken into account, thereby solving the technical problem of the coexistence of high protection and mild peelability in the existing technology, and achieving an excellent technical effect with balanced overall performance.

[0099] In some embodiments, the polyvinyl acetal resin is polyvinyl butyral (PVB) resin, which has the following structural formula:

[0100]

[0101] To ensure that the material has good film-forming properties and suitable solubility characteristics, the molecular weight of the polyvinyl butyral resin used is between 5 g / mol and 10,000 g / mol. As specific, non-limiting examples, the molecular weight of the polyvinyl butyral resin can be 5 g / mol, 100 g / mol, 500 g / mol, 1,000 g / mol, 5,000 g / mol, or 10,000 g / mol.

[0102] PVB was chosen as the core structural resin because it contains a significant proportion of hydroxyl groups, which enable the polymer to form hydrogen bonds within and between molecules, increasing the intermolecular forces. Furthermore, due to the presence of hydroxyl groups on the molecular chain, PVB can also undergo cross-linking reactions with other thermosetting resins, such as phenolic, urea-formaldehyde, melamine, epoxy, and diisocyanates. By mixing these in appropriate proportions, the brittleness and adhesion of the product can be improved, and bridging reactions can be generated to enhance chemical resistance and film hardness.

[0103] Specifically, PVB also has excellent film-forming properties, transparency, and excellent mechanical toughness, providing a strong and flexible basic skeleton for composite materials. In addition, the presence of both hydrophobic butyral groups and hydrophilic alcoholic hydroxyl groups on the PVB molecular chain makes this amphiphilic structure have excellent adhesion to polar surfaces such as metals (such as copper) and inorganic materials (such as glass substrates), while also maintaining good compatibility with other organic resins in the system.

[0104] More importantly, the alcoholic hydroxyl groups on the PVB molecular chain not only provide adhesion but also possess chemical reactivity. During the curing process, these hydroxyl groups undergo a cross-linking reaction with the epoxy and phenolic resins in the binder resin, rendering the PVB matrix no longer isolated but deeply integrated into the entire cross-linked network through chemical bonding. This co-reaction significantly enhances the cohesive strength, heat resistance, and overall structural density of the final protective film, making it more resistant to high temperatures, high pressures, and chemical corrosion.

[0105] Finally, despite the cross-linking reaction, PVB's main chain structure and moderate cross-linking allow the entire system to maintain its strength while retaining the ability to swell or dissolve in specific mild solvents such as alcohols. Furthermore, by adjusting the ratio of alcoholic hydroxyl groups, acetoxy groups, and butyral groups in the PVB raw material, its solubility, water resistance, and compatibility with other components can be precisely fine-tuned.

[0106] In some embodiments, the chemical composition of the PVB resin itself can be carefully selected to further precisely control the material's solubility, water resistance, and compatibility with other components. Specifically, in the polyvinyl butyral resin, the weight percentage of polyvinyl alcohol (PVA), a source of hydrophilicity, can range from 11% to 27%, for example, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, and 27%. The weight percentage of polyvinyl acetate can range from 0% to 8%, for example, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8%. By adjusting the ratios of these groups, the final protective film's behavior in different solvents and its hydrolysis resistance can be fine-tuned.

[0107] Preferably, in the polyvinyl butyral resin, the weight percentage of polyvinyl alcohol is between 18% and 21%, and the weight percentage of polyvinyl acetate is between 1% and 6%.

[0108] Specifically, the preference for the content of polyvinyl alcohol (alcohol hydroxyl group) is intended to achieve the best balance between adhesion, reactivity and water resistance. Within the wider functional range of the present invention (11% to 27%), when the polyvinyl alcohol content is in a lower range (such as 11% to 18%), the composite material already has good strippability and sufficient adhesion, and exhibits stronger water resistance. When its content is in a higher range (such as 21% to 27%), the adhesion and reactivity of the material will be further enhanced, and the stripping speed in alcohol solvents may also be faster, but the sensitivity to moisture will increase accordingly. In contrast, controlling the polyvinyl alcohol content within the preferred optimal window of 18% to 21% can provide excellent adhesion and cross-linking reactivity sufficient to cope with various harsh processes while maintaining the hydrophilicity of the material at an ideal level, thereby maximizing its bonding and curing properties without sacrificing water resistance, and obtaining the most balanced overall effect.

[0109] Similarly, the optimization of the polyvinyl acetate (acetoxy) content is intended to fine-tune the synergy between the hydrophobicity and core functionality of the material. Within its wider functional range (0% to 8%), when the polyvinyl acetate content is in a higher range (such as 6% to 8%), although it can further improve the hydrolysis resistance of the material, it may slightly dilute the concentration of alcoholic hydroxyl groups, thereby having a subtle effect on adhesion or reactivity. By controlling its content within the preferred range of 1% to 6%, a sufficient amount of hydrophobic groups is introduced, which can significantly optimize and improve the water resistance and environmental stability of the final protective film, but its content is not enough to cause any substantial negative impact on the core function of alcoholic hydroxyl groups (providing adhesion and reaction sites). Therefore, this range is the best choice for effectively enhancing the weather resistance of the material without sacrificing core performance.

[0110] In summary, by limiting the content of polyvinyl alcohol and polyvinyl acetate to the preferred optimal window of 18%-21% and 1%-6%, respectively, the PVB structural resin can achieve an optimal balance in the key performance dimensions of adhesion, reactivity, water resistance and solubility in mild solvents.

[0111] In some embodiments, the ratio of the phenolic resin content to the epoxy resin content in the bonding resin satisfies the following formula:

[0112] Phenolic resin content=(hydroxyl equivalent of phenolic resin / epoxy equivalent of epoxy resin)×epoxy resin content.

[0113] The fundamental reason for using the above formula to determine the amount of the two resins is to follow the stoichiometric principle in chemical reactions, aiming to achieve an ideal balance in the number of the two core functional groups involved in the reaction, thereby obtaining a cured product with optimal performance.

[0114] Specifically, the curing process of adhesive resins primarily involves a ring-opening addition reaction between the phenolic hydroxyl groups (-OH) on the phenolic resin molecular chain and the epoxy groups on the epoxy resin molecular chain, forming a highly cross-linked three-dimensional network structure. To ensure the most complete and efficient reaction, theoretically, one phenolic hydroxyl group should react with exactly one epoxy group. Therefore, the ideal feed ratio should ensure that the total molar number of phenolic hydroxyl groups in the formula to the total molar number of epoxy groups is as close to 1:1 as possible.

[0115] Here, "Epoxy Equivalent Weight (EEW)" refers to the number of grams of epoxy resin per mole of epoxy groups, while "Hydroxyl Equivalent" refers to the number of grams of phenolic resin per mole of phenolic hydroxyl groups. These two values ​​are key parameters for measuring resin reactivity.

[0116] Therefore, the above formula essentially represents a mathematical conversion of the chemical equilibrium relationship: "moles of phenolic hydroxyl groups ≈ moles of epoxy groups." Using this formula, the amount of phenolic resin containing an equal number of moles of reactive sites required can be accurately calculated based on the amount of epoxy resin selected and its epoxy equivalent weight.

[0117] Using this stoichiometric approach to determine the ratio ensures the full cross-linking reaction and avoids a large number of unreacted functional groups remaining in the cured network due to an excess of one component. This ensures that the final cured adhesive resin has the highest cross-linking density, better heat resistance, chemical resistance, and the strongest mechanical strength and adhesion to the substrate.

[0118] In some embodiments, the high-performance organic polymer is selected from at least one of polyimide (PI), poly(p-phenylenebenzobisoxazole) (PBO), polybenzimidazole (PBI), benzoxazine, bismaleimide, and bismaleimide triazine.

[0119] Among them, the structural formula of polyimide is:

[0120]

[0121] The structural formula of poly(p-phenylene benzobisoxazole) is:

[0122] The structural formula of polybenzimidazole is:

[0123] The structural formula of benzoxazine is:

[0124] The benzoxazine disclosed in this patent can be copolymerized with epoxy resin to enhance the heat resistance and mechanical properties (such as hardness) of the composite resin of the present invention.

[0125] The following bisphenol A-type benzoxazine, bisphenol F-type benzoxazine, MDA-type benzoxazine, DCPD-type benzoxazine, phenol-type benzoxazine, DOPO-type benzoxazine, low-dipole moment diamine-type benzoxazine, double bond-type benzoxazine, and ODA-type benzoxazine can be used, without limitation.

[0126] Bisphenol A benzoxazine

[0127] Bisphenol A benzoxazine is the most common standard benzoxazine. It is made from bisphenol A, paraformaldehyde, and aniline through dehydration condensation. It is a yellow solid at room temperature with a melting point of around 70°C. It can self-level when heated to 120°C. G(t) = 300-800s @ 210°C. The cured glass transition temperature Tg is ≥ 170°C. The long-term operating temperature is 180-200°C. It has a V1 flame retardant rating, a water absorption rate of <0.2%, and a Rockwell hardness of 120.

[0128] Bisphenol F benzoxazine

[0129] Bisphenol F benzoxazine is a tough benzoxazine made from bisphenol F, paraformaldehyde, and aniline through dehydration condensation. It is a yellow solid at room temperature with a melting point of approximately 60°C. It can self-level when heated to 120°C, with a G(t) of 200-700s at 210°C. After curing, its glass transition temperature (Tg) is ≥170°C. It has a V1 flame retardant rating and offers superior toughness to bisphenol A benzoxazine, making it suitable for the preparation of composite materials.

[0130] MDA-type benzoxazine

[0131] MDA-type benzoxazine is a highly heat-resistant benzoxazine made from diaminodiphenylmethane, paraformaldehyde, and phenol through dehydration condensation. It is a brown-yellow solid at room temperature with a melting point of approximately 90°C. It can self-level when heated to 120°C, with a G(t) of 200-600s at 210°C. The cured benzoxazine has a glass transition temperature (Tg) of ≥200°C, a long-term operating temperature of 200-220°C, a V1 flame retardancy rating, and a carbon residue in a nitrogen atmosphere of >50% at 800°C. It is suitable for the preparation of products in high-temperature environments.

[0132] DCPD type benzoxazine

[0133] DCPD-type benzoxazine is a low-dielectric benzoxazine made from the dehydration condensation of dicyclopentadiene diphenol, paraformaldehyde, and aniline. It is a yellow solid at room temperature with a melting point of approximately 90°C. It can self-level when heated to 120°C. Its G(t) = 1000-3000s@210°C and a glass transition temperature (Tg) ≥ 150°C after curing are achieved. It has a V1 flame retardant rating and a dielectric constant (Dk) < 3.0 and a dielectric loss (Df) < 0.0095. Its excellent dielectric properties make it suitable for use in communications copper-clad laminates.

[0134] Phenol-type benzoxazine

[0135] Phenol-type benzoxazine is made by dehydration condensation of phenol, paraformaldehyde, and aniline. It is one of the simplest monocyclic benzoxazines. Due to its small steric hindrance and molecular structure, it has a melting point of around 40°C, low viscosity after melting, low curing temperature, and a glass transition temperature (Tg) ≥ 130°C after curing. It has a long-term use temperature and a V1 flame retardant grade, making it suitable for solvent-free low-viscosity systems, such as RTM molding.

[0136] DOPO-type benzoxazine

[0137] DOPO-type benzoxazine is a flame-retardant benzoxazine made from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, benzoxazine, paraformaldehyde, and phenol through dehydration condensation. It is a yellow solid at room temperature with a melting point of approximately 90°C. It can self-level when heated to 120°C. The cured benzoxazine has a glass transition temperature (Tg) of ≥150°C, a V0 flame retardancy rating, a phosphorus content of >9.0, and a low smoke density. It is halogen-free and can be used solely as a flame-retardant matrix resin or as a phosphorus-containing curing agent for epoxy resins. It is suitable for use in halogen-free flame-retardant composite materials and copper-clad laminates.

[0138] The structural formula of bismaleimide is:

[0139] The bismaleimide referred to in this patent can be copolymerized with epoxy resin to form an interpenetrating network structure, achieving synergistic effects and improving the heat resistance and mechanical properties (such as hardness and toughness) of the composite resin of the present invention. Modified bismaleimides are preferred, including, but not limited to, diaminodiphenylmethane (DDM)-modified bismaleimides, biphenyl-containing bismaleimides, isopropyl-p-phenylene bismaleimides, PI-modified bismaleimides, and cyanate-modified bismaleimides.

[0140] The structural formula of bismaleimide triazine can be referred to bismaleimide.

[0141] The above materials have high chemical resistance, high Tg point and good film-forming properties.

[0142] Specifically, because the molecular backbones of these polymers are composed of the aforementioned extremely stable aromatic and heterocyclic rings, resulting in extremely high chemical bond energy and a dense structure, they are extremely inert to attack by corrosive chemicals such as strong acids and bases. Incorporating these polymers into composite materials can significantly enhance the chemical resistance of the composites.

[0143] Secondly, a high Tg (glass transition temperature) indicates excellent thermal stability. Tg is the temperature at which a polymer transitions from a hard, glassy state to a soft, highly elastic state. These high-performance polymers have very high Tg points due to their rigid backbone structure, which makes molecular chains difficult to move. This ensures that the composite material will not soften, deform, or experience performance degradation during high-temperature processes (e.g., 180°C) such as multilayer lamination, maintaining its robust protective capabilities.

[0144] Finally, these materials have the ability to disperse in solvents and ultimately form a continuous, dense protective phase in the composite material. They are not just inert powder fillers, but can combine well with other resin components to build a defect-free, uniform protective film layer.

[0145] In some embodiments, the composite materials of the present application further include at least one of a leveling agent, a dispersant, and a defoaming agent. These additives can further improve the processing properties of the composite materials when prepared into inks or dry films, as well as the appearance quality of the final film layer (e.g., leveling, bubble elimination, etc.). Those skilled in the art can select the appropriate additive amount based on specific application requirements and process conditions to achieve optimal process suitability and film-forming results.

[0146] like Figure 1 As shown, in one embodiment of the present invention, the preparation process of the mildly peelable composite material includes the following steps:

[0147] S1. Preparing a first slurry: mixing a structural resin based on polyvinyl acetal resin, a binder resin comprising a phenolic resin and an epoxy resin, and a high-performance organic polymer having an aromatic ring and / or a heterocyclic ring in the main chain in a first solvent to obtain the first slurry.

[0148] This step aims to fully dissolve and evenly disperse all organic phase components beforehand to form a stable, uniform organic resin masterbatch. Specifically, the structural resin provides film-forming properties and toughness, the binder resin enhances adhesion and heat resistance through cross-linking, and the high-performance organic polymer forms a chemical-resistant barrier. This step allows for the pre-homogenization of various organic polymers with relatively similar chemical properties, laying the foundation for the subsequent introduction of inorganic fillers and the formation of a uniform final system.

[0149] In order to effectively dissolve or disperse the above-mentioned multiple organic components, in some embodiments, the first solvent may include at least one of the following substances: ethanol, acetone, butanone, cyclohexanone, toluene, xylene, or a mixed solvent formed therefrom.

[0150] In some embodiments, the mixing conditions for mixing the structural resin, the binder resin, and the high-performance organic polymer in the first solvent include:

[0151] a. The mixing speed is between 3600 rpm and 7200 rpm. Specifically, the structural resin, adhesive resin, and high-performance organic polymer can be added to a high-shear device such as an emulsifier and maintained at a speed between 3600 rpm and 7200 rpm, for example, 3600 rpm, 4500 rpm, 6000 rpm, or 7200 rpm. By limiting the mixing speed, sufficient mechanical energy can be provided to promote the rapid swelling, disentanglement, and dissolution of the various polymers in the solvent, thereby forming a molecularly uniform, clear or translucent organic resin mother liquor.

[0152] b. The temperature of the mixed slurry is not higher than 45°C. Specifically, during the high-speed mixing process, the system can be cooled by means of a cooling water jacket or other means to ensure that the overall temperature of the slurry is always maintained at a level not higher than 45°C, for example, 25°C, 35°C, or 45°C. Because the first slurry contains heat-sensitive thermosetting components such as phenolic resin and epoxy resin, strict temperature control can effectively avoid undesirable pre-curing or gelation reactions caused by high shear heat generation, thereby ensuring the storage stability and subsequent processing performance of the first slurry.

[0153] c. The mixing time is between 60 and 120 minutes. Specifically, under the aforementioned speed and temperature conditions, the mixing process can be controlled to last between 60 and 120 minutes, for example, 60, 90, or 120 minutes. This mixing time ensures that the high molecular weight components in the system have sufficient time to completely dissolve and disperse, achieving a stable, homogeneous equilibrium state, thereby avoiding uneven performance in the final product due to insufficient mixing.

[0154] To further enhance the uniformity and stability of the first slurry and ensure that all solid components are effectively dispersed, in some embodiments, the step of preparing the first slurry may further include an optimized material addition sequence. Specifically, before adding the main solid resin components, such as the structural resin, binder resin, and high-performance organic polymer, to the first solvent, one or more additives, such as a dispersant and / or defoamer, are pre-dissolved or dispersed in the first solvent to form an additive mother solution.

[0155] Adopting this additive-first order has significant technical advantages. For the dispersant, pre-dissolving it in the solvent allows its molecules to be immediately and efficiently adsorbed to the surface of the solid particles when the solid powder is subsequently added, forming an effective steric hindrance or electrostatic repulsion layer. This prevents the initial agglomeration of particles due to excessively high surface energy from the source. Compared with the method of adding all materials together or adding the dispersant later, a dispersed system with smaller particle size, more uniform distribution, and better long-term stability can be obtained. Similarly, pre-adding a defoamer can effectively reduce the surface tension of the solvent, thereby suppressing the formation of stable foam from the beginning when air is introduced during high-speed stirring, ensuring the density of the final slurry and the quality of subsequent coating and film formation.

[0156] S2. Prepare a second slurry: Mix an inorganic filler whose surface is modified with at least one functional group selected from the group consisting of aniline groups, nitrogen-containing functional groups on the main chain or side chains, double bond-containing functional groups, and epoxy groups in a second solvent to obtain the second slurry.

[0157] The core purpose of this step is to independently and specifically carry out efficient deagglomeration and surface wetting treatment on the inorganic filler. The inorganic filler forms a chemical or physical bond with the resin matrix through the surface modification functional group, thereby improving the dispersibility and mechanical properties (such as hardness). Since there is no interference from the high-viscosity polymer resin in the second slurry, the mechanical energy of the mixing equipment (such as a high-shear emulsifier) ​​can act more effectively on the surface of the inorganic filler particles, thereby completely breaking up the original agglomerates caused by van der Waals forces and other reasons, ensuring that each particle can be fully wetted by the solvent and the dispersant that may be added, forming a stable and fine inorganic phase suspension.

[0158] To ensure effective wetting and stable dispersion of the inorganic filler particles, in some embodiments, the second solvent may include at least one of the following substances: ethanol, acetone, butanone, cyclohexanone, toluene, xylene, or a mixed solvent thereof.

[0159] In some embodiments, when the inorganic filler is mixed in the second solvent, the mixing conditions include:

[0160] a. Mixing speed between 3600 rpm and 7200 rpm. Specifically, the inorganic filler can be added to a high-shear device such as an emulsifier, and the speed is controlled to maintain between 3600 rpm and 7200 rpm. Unlike the first slurry, the main purpose of the high speed here is to provide strong mechanical shear force to overcome the strong forces generated by van der Waals forces and other forces between the fine particles of the inorganic filler, thereby completely breaking up the original, hard agglomerates and restoring them to a finely dispersed state close to the original particle size.

[0161] b. The temperature of the mixed slurry should not exceed 45°C. Specifically, the temperature of the second slurry should also be controlled at no higher than 45°C. The primary purpose of temperature control is to maintain the stability of the dispersion. The performance of some dispersants may decrease with increasing temperature. Lower temperatures also help suppress Brownian motion of particles, thereby reducing the tendency for particles to collide and aggregate again, ensuring the stability of the prepared inorganic filler suspension.

[0162] c. Mixing time is between 60 and 120 minutes. Specifically, the mixing process can be controlled to last between 60 and 120 minutes. For inorganic fillers, deagglomeration is a process that requires continuous energy input. By limiting the mixing time, it is possible to ensure that the high shear force has sufficient time to break up the majority of agglomerates and allow the dispersant molecules to fully coat the particle surface, forming a stable steric hindrance or electrostatic repulsion layer, thereby obtaining a uniformly dispersed and stable inorganic filler slurry.

[0163] Similarly, to ensure that the inorganic filler, which serves as a physical barrier and mechanical reinforcement core, is thoroughly deagglomerated and stably dispersed, in some embodiments, an optimized material feeding sequence is employed in the preparation of the second slurry. Specifically, the dispersant and / or defoaming agent is also pre-dissolved or dispersed in the second solvent before the surface-modified inorganic filler is added.

[0164] This step is particularly important for the dispersion of inorganic fillers. Because inorganic filler particles, especially those that have been surface-modified or have a smaller particle size, have extremely high surface energy and a strong tendency to agglomerate, preparing the dispersant in the solvent in advance can ensure that under the action of high shear forces, the newly exposed particle surfaces can be wetted and coated by the dispersant molecules as soon as possible. This maximizes the dispersion efficiency and can obtain a smaller and more stable particle dispersion system, which directly determines the density of the final protective film and the upper limit of its protective ability. The pre-addition of the defoaming agent can effectively avoid the large amount of foam generated by the entrapment of air during high-intensity stirring of the powder, ensuring the uniformity of the second slurry and the smooth progress of subsequent mixing operations.

[0165] S3. Mixing: Mixing the second slurry with the first slurry to obtain a mixed slurry that can be gently peeled.

[0166] Specifically, by mixing the second slurry (a fully dispersed inorganic phase) with the first slurry (a fully homogenized organic phase), a final, gently peelable mixed slurry is obtained. Because both phases have reached a highly uniform and stable state during their respective pre-preparation steps, the final mixing process more easily achieves uniform distribution of the inorganic filler within the organic polymer matrix, effectively avoiding the filler agglomeration and uneven dispersion issues common in traditional "one-pot" mixing processes.

[0167] In order to ensure that the two phases can be evenly fused without secondary agglomeration, in some embodiments, the step of preparing the mixed slurry includes:

[0168] S31. Slowly add the second slurry into the first slurry being stirred.

[0169] Specifically, the second slurry, the inorganic phase, can be delivered to the mechanically stirred first slurry, the organic phase, at a controlled, low flow rate using a peristaltic pump, dropping funnel, or other delivery device. For example, the entire addition process can be completed within 10 to 30 minutes. This slow, controlled addition method avoids mixing "shock" caused by the significant difference in viscosity and polarity between the two slurries, effectively preventing secondary agglomeration of the pre-dispersed inorganic filler particles when entering the high-viscosity resin system, and ensuring smooth and uniform integration of the two phases.

[0170] S32. After the second slurry is added, continue mixing for 60 to 120 minutes.

[0171] Specifically, after the second slurry is fully added to the first slurry, the set high shear stirring conditions are maintained, for example, for 60 minutes, 90 minutes, or 120 minutes. By limiting this subsequent homogenization time, it is possible to ensure that the inorganic filler particles that have entered the organic phase matrix have sufficient time to be thoroughly and evenly dispersed throughout the system, thereby achieving a stable, highly uniform final equilibrium state both macroscopically and microscopically.

[0172] S33. During the mixing process, the temperature of the mixed slurry is maintained at no higher than 45°C.

[0173] Specifically, during the entire process of slow addition in sub-step S31 and continuous mixing in sub-step S32, it is necessary to continuously remove the heat generated by the high-intensity stirring of the system through a cooling water jacket or other means. For example, the slurry temperature control target can be set at 25°C, 35°C, or any value not higher than 45°C. By strictly controlling the temperature throughout the final mixing process, its core purpose is to continuously suppress the reactivity of the thermosetting resin component, thereby completely eliminating the risk of gelation caused by the accumulation of heat due to long-term stirring, and ensuring the excellent storage stability and process applicability of the final mixed slurry.

[0174] like Figure 2 As shown, in some embodiments, after obtaining the mixed slurry, the preparation process of the present application further includes:

[0175] S4, film formation: The mixed slurry is coated on the substrate film and dried at a temperature of 50°C to 120°C for 3 to 10 minutes. The purpose of this step is to convert the liquid slurry into a solid dry film product that is easy to store, transport and use.

[0176] Among them, the substrate film can be a carrier film with good flatness and temperature resistance such as polyethylene terephthalate (PET) film, and the coating method can adopt blade coating, slit coating or comma coating technology to obtain a wet film of the required thickness.

[0177] Furthermore, after coating, the substrate film with the slurry coating is placed in a hot air oven or similar heating device for drying. In some embodiments, drying can be performed at a temperature of 50°C to 120°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, and for a duration of 3 to 10 minutes, for example, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, or 10 minutes. The primary purpose of this drying step is to remove residual solvent from the slurry and solidify the film layer, rather than completely crosslinking it. Controlling the temperature within the specific range of 50°C to 120°C ensures efficient solvent evaporation to produce a pinhole-free, dense dry film while also preventing significant pre-curing of the thermosetting resin components in the system due to excessively high temperatures. This ensures that the resulting dry film product maintains its desired flexibility, adhesion activity, and processing properties before use.

[0178] It can be understood that the preparation process of this application adopts the core concept of step-by-step pulping. By separating the pre-dispersion steps of the organic phase components (in the first slurry) and the inorganic phase components (in the second slurry) with very different chemical properties, it is possible to focus and efficiently de-agglomerate the most difficult-to-disperse inorganic fillers, avoiding the agglomeration problem that will inevitably occur when they are directly mixed in a viscous polymer system. As a result, a mixed slurry with extremely uniform dispersion of inorganic fillers can be prepared, thereby ensuring that the protective material that is finally cured into a film has a dense, uniform and defect-free microstructure, greatly improving the reliability and stability of its protective performance.

[0179] At the same time, by precisely controlling key physical parameters during the mixing process (such as rotational speed and temperature), particularly high-shear mixing at low temperatures, the premature gelation of the thermosetting resins (phenolic and epoxy resins) in the system, which can occur due to heat generation during high-intensity mechanical stirring, is effectively suppressed. This significantly widens the process window, reduces production scrap rates, and enables industrialized, large-scale production of this complex formulation, ensuring consistent performance across batches.

[0180] Furthermore, because the preparation process of this application overcomes the aforementioned production issues, the composite material prepared using this process, due to its uniform and dense internal structure, can reliably withstand chemical attack from strong acids and bases, as well as physical impact from high temperatures and high pressures. Furthermore, the uniform dispersion maximizes the effectiveness of the adhesive resin and functional filler, ensuring a secure bond between the material and the substrate and excellent surface hardness. Furthermore, this process ensures that the polyvinyl acetal resin, serving as the strippable matrix, forms a complete, continuous network, enabling gentle solvent stripping.

[0181] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A process for preparing a composite material that can be gently peeled, characterized in that: include: Preparing a first slurry: mixing a structural resin based on a polyvinyl acetal resin, a binder resin comprising a phenolic resin and an epoxy resin, and a high-performance organic polymer having an aromatic ring and / or a heterocyclic ring in a main chain in a first solvent to obtain the first slurry; Preparing a second slurry: mixing an inorganic filler whose surface is modified with at least one functional group selected from the group consisting of aniline groups, nitrogen-containing functional groups on the main chain or side chains, double bond-containing functional groups, and epoxy groups in a second solvent to obtain the second slurry; and Mixing: Mixing the second slurry with the first slurry to obtain a mixed slurry that can be gently peeled.

2. The process for preparing the gently peelable composite material according to claim 1, wherein: The mixing conditions for mixing the structural resin, the binder resin and the high-performance organic polymer in the first solvent and the inorganic filler in the second solvent include: The mixing speed is between 3600 rpm and 7200 rpm; The temperature of the mixed slurry is not higher than 45℃; The mixing time ranged from 60 minutes to 120 minutes.

3. The process for preparing the gently peelable composite material according to claim 1, wherein: The step of preparing the first slurry further includes: pre-dissolving or dispersing a dispersant and / or a defoaming agent in the first solvent before adding the structural resin, the binder resin, and the high-performance organic polymer to the first solvent; and The step of preparing the second slurry further includes: pre-dissolving or dispersing a dispersant and / or a defoaming agent in the second solvent before adding the inorganic filler into the second solvent.

4. The process for preparing the gently peelable composite material according to claim 3, wherein: The first solvent and / or the second solvent include at least one of the following substances: Ethanol, acetone, butanone, cyclohexanone, toluene, xylene.

5. The process for preparing the gently peelable composite material according to claim 3, wherein: The steps of preparing the mixed slurry include: Slowly adding the second slurry to the stirred first slurry; After the addition of the second slurry is completed, mixing is continued for 60 minutes to 120 minutes; and During the mixing process, the temperature of the mixed slurry was kept below 45°C.

6. The process for preparing a gently peelable composite material according to any one of claims 1 to 5, characterized in that: After obtaining the mixed slurry, the preparation process further comprises: Film formation: The mixed slurry is coated on a substrate film and dried at a temperature of 50° C. to 120° C. for 3 to 10 minutes.

7. The process for preparing the gently peelable composite material according to claim 6, wherein: The polyvinyl acetal resin is polyvinyl butyral resin.

8. The process for preparing the gently peelable composite material according to claim 6, wherein: The high-performance organic polymer is selected from at least one of polyimide, poly(p-phenylene benzobisoxazole), polybenzimidazole, benzoxazine, bismaleimide, and bismaleimide triazine.

9. The process for preparing a gently peelable composite material according to claim 6, wherein: The inorganic filler is selected from at least one of graphite, carbon black, graphene, silicon dioxide, aluminum oxide, aluminum hydroxide, calcium carbonate, magnesium carbonate, magnesium silicate, silicon carbide, titanium carbide, titanium oxide, magnesium oxide, calcium oxide, boron nitride, and aluminum nitride.

10. The process for preparing a gently peelable composite material according to claim 6, wherein: The component contents of the mixed slurry are: The weight percentage of the structural resin is between 40% and 90%; The weight percentage of the bonding resin is between 5% and 40%; The weight percentage of the high performance organic polymer is between 5% and 50%; The weight percentage of the inorganic filler is between 0.5% and 40%.

Images