An enhanced electronic carrier sheet and a method of manufacturing

Abstract

This invention belongs to the field of special functional paper manufacturing technology, specifically relating to a reinforced electronic carrier paper and its preparation method. It includes a base paper layer and a surface sizing layer attached to at least one surface of the base paper layer. The base paper layer includes 0.05%-2% cationic nano-reinforcing agent by weight of oven-dry pulp, with a zeta potential of +5 to +100 mV. The surface sizing layer includes a bio-based heat-resistant resin and an anionic nano-reinforcing agent, with the anionic nano-reinforcing agent accounting for 2%-25% of the surface sizing layer by weight, and having a zeta potential of -5 to -100 mV. The use of cationic nano-reinforcing agents in the base paper allows for efficient anchoring to the fiber network via electrostatic adsorption, strengthening internal bonding and inhibiting paper dust generation. The surface sizing layer utilizes anionic nano-reinforcing agents and bio-based heat-resistant resin to construct a nanocomposite film, precisely controlling surface energy and thermal and moisture stability.

Description

Technical Field

[0001] This invention belongs to the field of special functional paper manufacturing technology, specifically relating to an enhanced electronic carrier paper and its preparation method. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Electronic carrier tape, as a core consumable in surface mount technology (SMT) for carrying, transporting, and protecting microelectronic components, directly determines the stability of the SMT production line and the component placement yield. Qualified electronic carrier tape must meet the following requirements: dust content ≤ 50 particles / m². 2 Peel strength fluctuates within ±15% from room temperature to harsh environments (85℃ / 85%RH, 96 h); moisture expansion rate after moisture absorption is ≤0.1%.

[0004] Electronic carrier tapes typically have an sizing layer on their surface to enhance the bonding strength between the layers of the carrier base paper, improve adhesion compatibility with the top sealing tape, control peel strength stability, improve water and moisture resistance, and reduce lint generation. Existing surface sizing layers generally use petroleum-based sizing resins. These resins are non-renewable and have a long biodegradation period. More importantly, the glass transition temperature (Tg) of these resins is generally below 150°C. In high-temperature and high-humidity environments, the molecular chain segment movement intensifies, leading to a non-linear decay in peel strength (industry measurements show that peel strength fluctuations often exceed ±25% after 48 hours at 85°C / 85%RH), severely impacting the reliability of component handling.

[0005] Current technologies typically improve dry strength by increasing the degree of beating. However, increasing the degree of beating can easily lead to excessive fiber cutting, significantly increasing the paper's brittleness index and causing micron-sized paper dust to contaminate components during high-speed operation. Adding synthetic dry strength agents such as polyacrylamide is not only costly, but their cationic properties also make them more prone to charge neutralization with subsequent anionic sizing resins, leading to defects such as pinholes and orange peel in the coating, and compromising surface functional uniformity. Therefore, these methods can only improve the mechanical strength of the paper base and cannot simultaneously address the issues of surface peel strength stability and environmental adaptability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide an enhanced electronic carrier paper and its preparation method.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a reinforced electronic carrier paper, comprising a base paper layer and a surface adhesive layer attached to at least one surface of the base paper layer, wherein, The base paper layer includes 0.05%-2% cationic nano-reinforcing agent by weight of oven-dry pulp, and the zeta potential of the cationic nano-reinforcing agent is +5~+100 mV; The surface layer includes a bio-based heat-resistant resin and anionic nano-reinforcing agents. The mass percentage of the anionic nano-reinforcing agents in the surface layer is 2%-25%, and the zeta potential of the anionic nano-reinforcing agents is -5 to -100 mV.

[0008] In a second aspect, the present invention provides a method for preparing the enhanced electronic carrier paper, comprising the following steps: adding a cationic nano-reinforcing agent to pulp to obtain base paper; The coating solution, comprising a bio-based heat-resistant resin and anionic nano-reinforcing agents, is applied to at least one surface of the base paper, and then dried and cured to obtain the final product.

[0009] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: In this invention, cationic nano-reinforcing agents are used in the base paper, which are efficiently anchored to the fiber network by electrostatic adsorption, thereby strengthening the internal bonding force and inhibiting the generation of paper dust from the source. The surface adhesive layer uses anionic nano-reinforcing agents and bio-based heat-resistant resin (environmentally friendly heat-resistant resin) to construct a nanocomposite film. Through electrostatic attraction and hydrogen bonding, a continuous resin phase + nanocellulose skeleton composite film layer is constructed, which precisely controls the surface energy and thermal and humidity stability, and significantly improves the peel strength stability and dimensional stability under high temperature and high humidity environments. Detailed Implementation

[0010] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0011] Terminology Explanation Electronic carrier paper: refers to a special packaging paper-based material used in surface mount technology (SMT) to carry, transport, and protect micro-electronic components. Its core performance indicators include: low surface dust content, stable peel strength, and excellent dimensional stability under high temperature and humidity.

[0012] Nanocellulose: refers to cellulose fibers or whiskers with diameters between 1 and 100 nm and lengths ranging from hundreds of nanometers to tens of micrometers. They are derived from natural plant fibers or bacterial cellulose and are typically produced through chemical treatment, mechanical processing, or enzymatic hydrolysis. Their high specific surface area, high aspect ratio, and rich hydroxyl content give them excellent film-forming properties, reinforcing ability, and interfacial bonding potential.

[0013] Cationic cellulose nanoparticles: These refer to cellulose nanoparticles that acquire a positive charge on their surface through chemical modification or physical adsorption. In this invention, their zeta potential can be +5 to +100 mV, and even further, +15 to +35 mV. They are mainly used in the wet end of papermaking, utilizing their positive charge to efficiently bond with negatively charged pulp fibers through electrostatic adsorption.

[0014] Anionic nanocellulose: refers to nanocellulose with a negative charge on its surface due to the presence of carboxyl groups, sulfonic acid groups, etc. In this invention, its zeta potential can be -5 to -100 mV, and even further -20 to -40 mV. It is mainly used for coating paper surfaces, and by compounding with negatively charged or neutral bio-based resins, functional coatings are constructed.

[0015] Bio-based heat-resistant resin: refers to a polymer material made primarily from natural renewable biomass (usually accounting for ≥50%), through chemical modification or graft copolymerization to introduce functional monomers. In this invention, it specifically refers to an aqueous dispersion suitable for surface coating.

[0016] Zeta potential, referring to the potential at the shear plane, is a key indicator characterizing the stability and surface charge properties of colloidal dispersions. In this invention, it is used to quantitatively describe the surface charge properties and intensity of nanocellulose in aqueous solutions.

[0017] Retention rate: refers to the proportion of functional additives added to the pulp during the wet end of papermaking that are ultimately retained in the paper sheet. A high retention rate means effective utilization of the additives and a lower white water system load. This invention significantly improves the retention rate in the wet end through charge design.

[0018] Peel force: This refers to the force required to separate the packaged micro-components from the sealing film or perforations of the carrier tape. This indicator is a core standard for evaluating the performance of electronic carrier tape. One of the core technical effects this invention focuses on is controlling the fluctuation range of peel force within ±15% under simulated harsh environmental conditions to ensure the stable operation of automated mounting production lines.

[0019] Dust content: refers to impurities or dust spots that are significantly different in color from the paper surface per unit area (usually square meters). For electronic carrier paper, a low dust content (especially 0.1-0.3 mm) is desirable. 2 The level of micro-dust is crucial to prevent contaminants from adsorbing onto component terminals or pads during component pick-up, thereby ensuring soldering yield.

[0020] Moisture swelling rate: refers to the rate of dimensional change (usually transverse) of paper caused by fiber swelling due to moisture absorption when immersed in water or placed in a high-humidity environment. A low moisture swelling rate is a key indicator for ensuring consistent punching accuracy, stable hole positions, and good compatibility with automated equipment in humid and hot environments for electronic carrier paper. This invention achieves a low moisture swelling rate through the dual effects of a wet-end nanonetwork suppressing fiber swelling and a surface sizing film providing dimensional constraints.

[0021] To address the technical problems mentioned in the background section, this invention provides an enhanced electronic carrier paper, comprising a base paper layer and a surface adhesive layer attached to at least one surface of the base paper layer, wherein... The base paper layer includes 0.05%-2% cationic nano-reinforcing agent by weight of oven-dry pulp, and the zeta potential of the cationic nano-reinforcing agent is +5~+100 mV; The surface layer includes a bio-based heat-resistant resin and anionic nano-reinforcing agents. The mass percentage of the anionic nano-reinforcing agents in the surface layer is 2%-25%, and the zeta potential of the anionic nano-reinforcing agents is -5 to -100 mV.

[0022] Adding nano-reinforcing agents such as nanocellulose to paper can effectively improve the mechanical strength of paper, reduce the air permeability and water vapor permeability of paper, make the paper surface smoother, reduce roughness, and increase the tightness and density of paper. However, the inventors found that if nanocellulose and other substances are directly added to pulp for papermaking, the retention rate of unmodified nanocellulose is generally less than 50% due to the high density of hydroxyl groups and negative charge on the surface (Zeta potential ≈ -30 mV), which strongly electrostatically repels the negatively charged pulp fibers. This results in raw material waste and increased load on the white water system. During the surface coating stage, nanocellulose is prone to irreversible aggregation due to strong hydrogen bonding, forming micron-sized aggregates, which leads to excessive surface roughness of the coating (Ra > 2.0 μm), affecting the placement accuracy of components. Furthermore, its thermal decomposition initiation temperature is about 240-260℃, and it is prone to local carbonization at the peak reflow soldering temperature (260℃). Using it alone is difficult to guarantee the structural integrity under high-temperature conditions.

[0023] This invention proposes a technical concept that integrates reinforcement and functionalization processes in two key papermaking steps, creating a synergistic effect. Specifically, the wet-end pathway involves adding cationic nano-reinforcing agents such as cationic nanocellulose to construct and strengthen the nano-reinforcing network within the paper matrix, inhibiting fiber swelling and paper dust generation, thereby addressing the issues of paper matrix structural strength and cleanliness.

[0024] The surface coating approach involves coating a composite liquid of anionic nano-reinforcing agents such as anionic nanocellulose and bio-based heat-resistant resin to construct a dense, functional nanocomposite film on the paper surface, thus solving the problems of surface peel stability and dimensional stability. The specific reasons are as follows: The high aspect ratio and surface hydroxyl groups of anionic nano-reinforcing agents such as anionic nanocellulose can form physical cross-linking points with resin molecular chains, constructing a dense composite film of continuous resin phase + nanocellulose skeleton. This structure can suppress excessive movement of resin molecular chain segments under high temperature and high humidity conditions, avoid the nonlinear decay of peel force caused by Tg (glass transition temperature) below 150℃ of traditional petroleum-based resins, and reduce the peel force fluctuation range by more than 30% compared with conventional starch-coated products, thus avoiding adhesion or damage to components during handling.

[0025] The density of the composite membrane reduces water vapor permeation, and combined with the inhibitory effect of nanocellulose on fiber swelling, the wet swelling rate is significantly reduced. The interface between the nanocomposite membrane and the base paper layer forms a gradient bond through charge matching (the cationic nano-reinforcing agent in the base paper layer and the anionic component in the surface sizing layer), further enhancing the overall structural stability. The dense composite membrane seals the surface micropores, which is beneficial for a significant improvement in paper surface cleanliness. The composite membrane can also constrain the dimensions of the paper, inhibiting its lateral wet swelling.

[0026] The nanocellulose nanoparticles used in the two pathways have opposite charges and clear division of labor, working together to achieve the final product performance of "internal strength and external toughness". The resulting product exhibits a peel force fluctuation of ≤±12% and a dust content of <35 particles / m² at 85℃ / 85%RH. 2 With a wet expansion rate of <0.08%, meeting IPC standards; raw material cost increase of <5%; bio-based content >70%; biodegradable; and advantages of high reliability, environmental adaptability, and green industrialization.

[0027] This invention uses a cationic modified nano-reinforcing agent to give its surface a positive charge, which then binds tightly to the negatively charged pulp fibers through electrostatic adsorption, thereby significantly improving wet end retention.

[0028] Through experiments, the inventors discovered that if the surface adhesive layer is made of petroleum-based epoxy resin and nano-silica composite, although the temperature resistance is improved, it deviates from the concept of green manufacturing. If only bio-based resin is used, complex modification processes such as silane coupling agents need to be introduced to improve interfacial compatibility, which not only increases the cost, but the acidic byproducts generated by the hydrolysis of the coupling agent may also corrode precision components.

[0029] In this invention, the cationic nano-reinforcing agent in the base paper layer and the anionic nano-reinforcing agent in the surface sizing layer form a charge complementarity through electrostatic attraction, constructing a gradient interface bond and enhancing the interfacial bonding force between the base paper and the surface sizing layer. The high aspect ratio and surface hydroxyl groups of the anionic nano-reinforcing agent (such as anionic nanocellulose) in the surface sizing layer can form hydrogen bonds and physical cross-linking points with the molecular chains of bio-based heat-resistant resin, constructing a dense composite film of "resin continuous phase + nanocellulose skeleton", avoiding coating defects caused by insufficient interfacial compatibility.

[0030] Bio-based heat-resistant resins such as starch-acrylate graft copolymers are selected, whose molecular structure combines the hydroxyl groups of starch (affinity with nanocellulose) and the flexible segments of acrylate (adaptable to the substrate). By introducing formaldehyde-free crosslinking monomers (such as N-hydroxymethylacrylamide), a three-dimensional network crosslinking of the resin and nano-reinforcing agent is achieved without the need for additional silane coupling agents.

[0031] In some embodiments, the cationic nano-reinforcing agent accounts for 0.2%-2% of the oven-dry pulp mass; Alternatively, the mass percentage of anionic nano-reinforcing agents in the surface adhesive layer may be 5%-20%.

[0032] For example, the cationic nano-reinforcing agent accounts for 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2% of the oven-dry pulp mass.

[0033] The mass percentage of anionic nano-reinforcing agents in the surface layer is 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0034] In some embodiments, the bio-based heat-resistant resin accounts for 30%-90% of the mass percentage in the surface adhesive layer.

[0035] In some embodiments, the cationic nano-reinforcing agent is selected from at least one of cationic cellulose nanoparticles, cationic starch nanoparticles, cationic chitosan nanoparticles, or zwitterionic cellulose nanoparticles. The zwitterionic nanocellulose is cationic in the original paper layer.

[0036] In some embodiments, the anionic nano-reinforcing agent is selected from at least one of anionic nanocellulose, anionic cellulose nanocrystals, anionic starch nanoparticles, anionic chitosan nanofibers, or zwitterionic nanocellulose. The zwitterionic nanocellulose is anionic in the surface layer.

[0037] Amphoteric nanocellulose has a charge that can change with pH environment. Through process adjustment, it can be made to be cationic in the wet part and anionic in the surface colloid, realizing the dual-path application of a single type of nanocellulose.

[0038] Cellulose nanofibers can exist in the form of incompletely discrete nanofibers, or in part as cellulose nanofiber whiskers (CNC), cellulose nanofibers (CNF), or a mixture thereof.

[0039] The raw materials for nanocellulose are not limited to wood pulp, microcrystalline cellulose, or agricultural waste, but can also include bacterial cellulose, seaweed cellulose, and regenerated cellulose from waste cotton textiles. Preparation methods are not limited to TEMPO oxidation, acid hydrolysis, or enzymatic-mechanical methods; mechanical grinding and alkali-urea dissolution-regeneration methods can also be used, as long as the desired size and surface charge properties of the cellulose can be obtained.

[0040] Preferably, the cationic nano-reinforcing agent is cationic nanocellulose with a Zeta potential of +15 to +35 mV; The anionic nano-reinforcing agent is anionic cellulose nanocrystals with a zeta potential of -20 to -40 mV.

[0041] The zeta potential of cationic nanocellulose can be precisely controlled between +15 and +35 mV through chemical modification, resulting in stronger electrostatic adsorption with negatively charged pulp fibers (whose zeta potential is typically -20 to -40 mV). Wet-end retention can reach over 80%, significantly higher than that of unmodified nanocellulose. In addition to the positive charge, the surface retains a large number of hydroxyl groups, which can form a hydrogen bond network with the fibers, further strengthening the internal binding force and inhibiting fiber swelling and paper dust generation.

[0042] Cationic cellulose nanofibers, with diameters ranging from 1 to 100 nm and lengths from hundreds of nanometers to tens of micrometers, can form a three-dimensional nanonetwork in pulp, improving the dry strength of paper while avoiding the increase in brittleness caused by over-beating. They can also bond with anionic cellulose nanofibers (such as anionic cellulose nanocrystals with a zeta potential of -20 to -40 mV) in subsequent sizing layers through charge complementarity, forming a gradient interface that enhances overall structural stability.

[0043] In comparison, while cationic starch nanocrystals are cheaper, they have insufficient charge density and aspect ratio; cationic chitosan nanofibers suffer from poor dispersibility and easy agglomeration.

[0044] More preferably, the cationic nanocellulose is obtained by grafting quaternary ammonium salt groups onto plant fibers after oxidative modification; the anionic cellulose nanocrystals are obtained by acid hydrolysis of microcrystalline cellulose.

[0045] In some embodiments, the bio-based heat-resistant resin is selected from at least one of starch-acrylate graft copolymers, cellulose derivatives grafted with acrylates, lignin-acrylate composite emulsions, vegetable oil-modified acrylic resins, or polylactic acid (PLA)-based aqueous dispersions.

[0046] The resin can be a single bio-based resin or a blend of two or more bio-based resins, to adjust Tg, flexibility, cost, etc.

[0047] Preferably, the acrylate monomer of the bio-based heat-resistant resin is selected from at least one of butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate, isobornyl acrylate, or methyl methacrylate.

[0048] Preferably, in the starch-acrylate graft copolymer, the mass ratio of starch matrix to acrylate monomer is 2-4:1; it also includes N-hydroxymethylacrylamide accounting for 0.5%-1.5% of the total mass of the copolymer as a formaldehyde-free crosslinking monomer.

[0049] The preparation process of starch-acrylate graft copolymer is as follows: using natural starch as the main chain, acrylate monomers are grafted onto the starch molecules under the action of an initiator to form a copolymer with a "starch backbone + polyacrylate side chain" structure. This material combines the film-forming and biodegradable properties of starch with the flexibility and weather resistance of polyacrylate. By introducing formaldehyde-free crosslinking monomers, a three-dimensional network structure of the coating can be constructed.

[0050] When the bio-based heat-resistant resin is an aqueous dispersion of starch-acrylate graft copolymer (solid content 30%~40%, glass transition temperature Tg=40~60℃), corn / cassava starch is used as the matrix (accounting for ≥60%), and monomers such as butyl acrylate are grafted to improve flexibility and heat resistance. ≤1% of N-hydroxymethylacrylamide is introduced as a formaldehyde-free crosslinking monomer. The cost of this resin is close to that of ordinary oxidized starch, it can withstand humid and hot environments above 85℃, and it has excellent biodegradability.

[0051] Preferably, the bio-based heat-resistant resin is the main continuous phase, microspheres, or microcapsules. The bio-based heat-resistant resin can not only serve as the main continuous phase of the surface adhesive, but can also exist partially or entirely in the form of microspheres or microcapsules, co-constructing a multi-scale composite coating with nanocellulose to regulate peel force, buffering properties, or thermal responsiveness.

[0052] In some embodiments, the base material of the base paper is selected from at least one of bleached softwood pulp, bleached hardwood pulp, bamboo pulp, straw pulp, or waste paper pulp.

[0053] Preferably, the mass ratio of bleached softwood pulp to bleached hardwood pulp in the base paper is 15-25:75-85.

[0054] Preferably, the base paper further includes 0.6%-1.2% by mass of a neutral sizing agent, which is an alkyl ketene dimer.

[0055] Alkyl ketene dimer (AKD) is used as a neutral sizing agent in reinforced electronic carrier paper. By forming a hydrophobic film on the surface of the base paper fibers, it reduces the paper's absorption of moisture, thereby lowering the moisture swelling rate after moisture absorption. This ensures that the carrier paper maintains dimensional stability even in high humidity environments, preventing pore displacement or deformation caused by fiber swelling. In synergy with cationic nano-reinforcing agents, it reduces inter-fiber voids and lint generation, lowers dust levels, and prevents contaminants from being adsorbed onto microelectronic components during transport.

[0056] The base paper can be a single layer, or a two- or multi-layer structure. Cationic nano-reinforcing agents can be added to all layers or to specific layers.

[0057] In some embodiments, the dry weight of the adhesive layer is 3-5 g / m². 2 .

[0058] In a second aspect, the present invention provides a method for preparing the enhanced electronic carrier paper, comprising the following steps: adding a cationic nano-reinforcing agent to pulp to obtain base paper; The coating solution, comprising a bio-based heat-resistant resin and anionic nano-reinforcing agents, is applied to at least one surface of the base paper, and then dried, cured, and calendered to obtain the final product.

[0059] In some embodiments, the pulp is a mixture of bleached softwood pulp and bleached hardwood pulp, with a freeness of 30-50°SR. Alternatively, the pulp may also contain a neutral sizing agent, which is an alkyl ketene dimer.

[0060] In some embodiments, the drying temperature is 200-250°C.

[0061] In some embodiments, the coating liquid further includes 0.01%-0.05% by mass of an antifoaming agent and 0.05%-0.15% by mass of a bactericide.

[0062] It can effectively avoid the use of precious metal catalysts, high-cost petroleum-based resins, or complex post-processing.

[0063] Nanocellulose can be pre-composite or physically blended with some resins or other functional nanomaterials (such as nano titanium dioxide or nano zinc oxide) to form a pre-dispersed composite slurry, which can then be used in the wet end or on the surface to improve dispersibility or impart additional functions (such as UV protection or antibacterial properties).

[0064] The coating method is not limited to "immersion sizing" and can employ any method that can form a functional layer on the paper base surface, such as blade coating, metered sizing press coating, curtain coating, or spray coating. The surface sizing functional layer can be a single-layer structure or a multi-layer structure. For example, a base layer mainly composed of resin can be coated first, followed by a reinforcing / functional layer rich in nanocellulose; or vice versa.

[0065] Without affecting the core performance, other functional additives, such as conductive agents, flame retardants, dyes, fluorescent whitening agents, and antistatic agents, can be introduced into the wet end or the surface sizing layer to give the carrier paper additional functions such as marking, antistatic properties, and flame retardancy.

[0066] Process integration and sequence variations can be considered for online composite processes, which involve performing a certain pretreatment simultaneously or continuously in the wet end of the paper machine before entering the surface coating stage, forming an integrated reinforced-functionalized production process.

[0067] The present invention will be further described below with reference to the embodiments.

[0068] Raw material description: Cationic cellulose nanoparticles: Bleached wood pulp was oxidized with TEMPO (NaBr 1 mmol / g, 2,2,6,6-tetramethylpiperidine-1-oxy radical 0.1 mmol / g, pH adjusted to 10 with NaClO, reaction at 0-4℃ for 2 h) to obtain carboxylated cellulose nanoparticles, which were then reacted with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) under alkaline conditions at 60℃ for 4 h, and purified by dialysis to obtain a dispersion (solid content 2.0%). Anionic nanocellulose: Microcrystalline cellulose was hydrolyzed with 64 wt% sulfuric acid (45℃, 30 min), centrifuged, dialyzed to neutral, and ultrasonically dispersed to obtain a dispersion (solid content 1.5%). Starch-acrylate graft copolymer: Corn starch and butyl acrylate are graft copolymerized at a mass ratio of 3:1 (initiated by ammonium persulfate, 70℃, N2 protection), and 0.8 wt% N-hydroxymethylacrylamide (NMA) is introduced as a crosslinking monomer. The emulsion polymerization yields an aqueous resin (solid content 35%). Before crosslinking, the Tg is approximately 50℃. After drying and crosslinking at 105℃, the thermal stability of the coating is significantly improved, and it can withstand short-term high temperatures of 260℃.

[0069] Example 1 A method for preparing reinforced electronic carrier paper includes the following steps: (1) Preparation of base paper layer: Take 20 kg of oven-dried bleached softwood sulfate pulp and 80 kg of hardwood sulfate pulp, and grind them to 40°SR. The pulp was diluted to a concentration of 3.5 wt%. Before flushing the pulp pump, cationic nanocellulose dispersion (0.5% of the oven-dry pulp mass based on oven-dry nanocellulose) and alkyl ketene dimer (AKD) emulsion (1.0% of the oven-dry pulp mass based on oven-dry alkyl ketene dimer) were added sequentially. After thorough mixing, the mixture was wire-fed (100 m / min) and subjected to three presses (linear pressure 50 / 300 / 400 kN / m) followed by drying in a drying cylinder at 30-100℃ (gradient drying in seven stages: 30-60℃, 50-70℃, 60-90℃, 80-100℃, 60-90℃, 50-70℃, and 30-60℃, with each stage drying for 90 seconds) to obtain a basis weight of 400 g / m³. 2 Raw paper.

[0070] Cationic nanocellulose binds tightly to negatively charged pulp fibers through electrostatic adsorption, significantly improving wet end retention (white water turbidity monitoring shows retention >80%), while also enhancing the internal hydrogen bond network of the paper base and reducing the tendency for moisture absorption and deformation.

[0071] (2) Surface coating: Preparation of coating solution: 40 g of environmentally friendly heat-resistant resin (starch-acrylate graft copolymer) (based on solid content), anionic nanocellulose dispersion with nanocellulose accounting for 10 wt% of the total solids of the coating solution, 0.03 g of silicone defoamer, 0.1 g of isothiazolinone bactericide, N-hydroxymethylacrylamide (0.32 g, accounting for approximately 0.8% of the resin solids), totaling 100 g, with the remainder being deionized water. Stir at 60°C for 30 min until homogeneous.

[0072] The coating is applied to the functional surfaces of the base paper using an immersion coating method, with the dry coating amount controlled at 4 g / m². 2 Drying with hot air at 200℃ (during this process, N-hydroxymethylacrylamide cross-links with the hydroxyl groups of starch and anionic nanocellulose to form a dense three-dimensional network).

[0073] The surface smoothness is then improved by hard calendering (linear pressure 50 kN / m, roller temperature 160℃), followed by slitting and winding to obtain the finished product.

[0074] Anionic nanocellulose is uniformly dispersed with resin through hydrogen bonding and cross-linking. After curing, it forms a nano-reinforced interface layer, which significantly improves the coating's temperature resistance, peel strength, and environmental stability.

[0075] Example 2 The difference from Example 1 is that the starch-acrylate graft copolymer in Example 1 is replaced with corn starch-2-ethylhexyl acrylate copolymer (2-ethylhexyl acrylate replaces butyl acrylate, and the rest of the synthesis conditions are the same, Tg≈45℃), and the rest is completely consistent with Example 1.

[0076] This solution improves the elongation at break of the coating by introducing long-chain flexible monomers, making it suitable for irregularly shaped components that require higher performance under repeated bending of the carrier tape.

[0077] Example 3 The difference from Example 1 is that in step (1), cationic cellulose nanoparticles are replaced with cationic starch nanoparticles (Zeta potential is +25 mV), while everything else is the same as in Example 1.

[0078] The preparation method of cationic starch nanoparticles is as follows: 10 g of starch is dispersed in ethanol to prepare a starch suspension. A mixed solution of 7.0 g of 3-chloro-2-hydroxypropyltrimethylammonium chloride and 2.8 g of sodium hydroxide (molar ratio 1:2) is added, and the mixture is reacted at 55 °C for 4 h. After the reaction is completed, the suspension is cooled to room temperature, washed with acetic acid-ethanol solution, and dried to obtain quaternary ammonium salt cationic starch. The cationic starch is dispersed in deionized water to prepare a suspension with a concentration of 3 wt%. The suspension is heated to 100 °C in a water bath with continuous stirring for 60 min. After the cationic starch solution is cooled to room temperature, it is added dropwise to ethanol and stirred continuously with ultrasound. The resulting suspension is centrifuged at 4000 rpm for 5 min, and the precipitate is washed with ethanol to obtain cationic starch nanoparticles.

[0079] Example 4 The difference from Example 1 is that in step (1), the cationic nanocellulose dispersion is replaced with cationic chitosan nano dispersion (Zeta potential is +40 mV), and everything else is the same as in Example 1.

[0080] The preparation method of cationic chitosan nano-dispersion is as follows: Chitosan powder is dissolved in 1% acetic acid solution to prepare a 1 mg / mL chitosan solution, and magnetic stirring is used to ensure complete dissolution; sodium hydroxide solution is slowly added dropwise to the acidic chitosan solution to adjust the pH of the system to about 5.0; under continuous magnetic stirring at room temperature, 0.1% sodium tripolyphosphate solution is slowly added dropwise to the chitosan solution (mass ratio of chitosan to sodium tripolyphosphate 3:1); after the addition is complete, the reaction is continued to be stirred for 1 h to ensure the reaction is complete; the suspension is allowed to stand for 30 min, and the precipitate is collected by high-speed centrifugation (10000 rpm, 10 min), and washed twice with distilled water to remove unreacted impurities. Finally, the purified nanoparticles are redispersed in deionized water to obtain cationic chitosan nano-dispersion.

[0081] Example 5 The difference from Example 1 is that in step (2), anionic cellulose nanoparticles are replaced with anionic starch nanoparticles (Zeta potential is -32 mV), while all other steps are the same as in Example 1.

[0082] The preparation method of anionic starch nanoparticles is as follows: Starch is added to deionized water under stirring to prepare a homogeneous starch slurry with a mass fraction of 10%. A 3 mol / L sulfuric acid solution (starch to sulfuric acid mass-to-volume ratio of 1:20) is slowly added to the slurry. The mixture is then placed in a constant temperature water bath at 4℃ and continuously stirred (100 rpm) for acid hydrolysis for 3 days. During this period, the sulfuric acid gradually hydrolyzes and removes the amorphous regions of the starch particles. After the reaction is complete, the reaction solution is centrifuged at 8000 rpm for 15 min, and the precipitate at the bottom is collected. The precipitate is repeatedly washed with deionized water until the pH of the washing solution is neutral. The washed precipitate is then freeze-dried to obtain anionic starch nanoparticles.

[0083] Example 6 The difference from Example 1 is that in step (2), the anionic nanocellulose is replaced with anionic chitosan nanodispersion (Zeta potential is -28 mV), and everything else is the same as in Example 1.

[0084] The preparation method of anionic chitosan nano-dispersion is as follows: chitosan powder is dissolved in 1% (v / v) aqueous acetic acid solution to prepare a 1% (w / v) transparent solution; 2,2,6,6-tetramethylpiperidine-1-oxy free radical (0.1 mmol / g relative to chitosan repeating unit) and NaBr (1 mmol / g) are added to the above solution; under ice-water bath (0-4℃) conditions, NaClO solution (effective chlorine content of about 8%) is slowly added dropwise, while the pH value of the reaction system is maintained at about 10.0 with 0.5 M NaOH solution, and the reaction is continuously stirred for 2 h until the pH value no longer decreases and remains stable; a small amount of ethanol is added to terminate the reaction, and then the product is placed in a dialysis bag and dialyzed in deionized water for 48 h to remove salt and small molecule impurities; the purified oxidized chitosan solution is subjected to high pressure homogenization or ultrasonic treatment to obtain nanoscale dispersion.

[0085] Example 7 The difference from Example 1 is that in step (1), the cationic nanocellulose dispersion is added at 1% of the dry weight of the pulp, based on the amount of oven-dried nanocellulose. Everything else is the same as in Example 1.

[0086] Example 8 The difference from Example 1 is that in step (1), the cationic nanocellulose dispersion is added at 2% of the oven-dry pulp mass, based on oven-dry nanocellulose. Everything else is the same as in Example 1.

[0087] Example 9 The difference from Example 1 is that in step (2), the amount of anionic nanocellulose dispersion added is such that nanocellulose accounts for 20 wt% of the total solids in the coating solution. Everything else is the same as in Example 1.

[0088] Example 10 The difference from Example 1 is that in step (2), the amount of anionic nanocellulose dispersion added is such that nanocellulose accounts for 2 wt% of the total solids in the coating solution. Everything else is the same as in Example 1.

[0089] Example 11 The difference from Example 1 is that the starch-acrylate graft copolymer in Example 1 is replaced with a cellulose derivative and butyl acrylate graft copolymer, Tg≈55℃, and the other conditions are the same as in Example 1.

[0090] The preparation method of the graft copolymer of cellulose derivative and butyl acrylate is as follows: 10 g of carboxymethyl cellulose powder is slowly added to deionized water and stirred and dissolved in a constant temperature water bath at 60 ℃ to form a homogeneous and transparent solution; high-purity nitrogen gas is introduced into the above solution for about 30 min; 0.20 g of initiator ammonium persulfate is dissolved in a small amount of deionized water and added to the reaction vessel; after stirring evenly for 10 min to initiate the reaction, 40 mL of butyl acrylate monomer is slowly added dropwise to the system through a constant pressure dropping funnel; after the monomer is added, the temperature is maintained and the reaction is continuously stirred for 2 h to allow the graft copolymerization reaction to proceed fully; after the reaction is completed, the product is cooled to room temperature; solvent precipitation method (adding ethanol to precipitate the polymer) is used, and the product is repeatedly washed until there is no residual monomer in the filtrate. The filtrate is then placed in a vacuum drying oven and dried to constant weight to obtain the final product.

[0091] Comparative Example 1 The difference from Example 1 is that in step (1), unmodified nanocellulose (solid content 2.0%, Zeta potential ≈ -30 mV) is used instead of cationic nanocellulose, the amount added is adjusted to 0.8% of the oven-dry pulp mass, and cationic polyacrylamide (CPAM, 0.03%) is used as a retention aid.

[0092] Surface coating: The amount of anionic nanocellulose added was adjusted to 8 wt% of the total solids in the coating solution, and the rest of the process was the same as in Example 1.

[0093] Comparative Example 2 The difference from Example 1 is that the cationic nanocellulose is omitted from the original paper layer; the surface sizing layer is replaced with a 5 wt% cationic oxidized starch solution (solid content), and the rest is the same as in Example 1.

[0094] Comparative Example 3 The difference from Example 1 is that the starch-acrylate graft copolymer in the surface layer is replaced with an aqueous acrylic emulsion (solid content of about 40%, Shandong Kunhan New Material Technology Co., Ltd.), the amount of anionic nanocellulose added is the same as in Example 1, and the rest is the same as in Example 1.

[0095] Comparative Example 4 The difference from Example 1 is that in step (1), unmodified nanocellulose (solid content 2.0%, Zeta potential ≈ -30 mV) is used instead of cationic nanocellulose, while all other steps are the same as in Example 1.

[0096] Comparative Example 5 The difference from Example 1 is that in step (2), unmodified nanocellulose (solid content 2.0%, Zeta potential ≈ -30 mV) is used instead of anionic nanocellulose, and everything else is the same as in Example 1.

[0097] Comparative Example 6 The difference from Example 1 is that N-hydroxymethylacrylamide is omitted in step (2), while everything else is the same as in Example 1.

[0098] Comparative Example 7 The difference from Example 1 is that in step (2), the alkyl ketene dimer (AKD) emulsion is omitted, while everything else is the same as in Example 1.

[0099] Performance verification and analysis: Peel strength (0402 package resistor, peel speed 300 mm / min) was tested according to IPC-TM-650 2.4.9, and was carried out at room temperature (25℃ / 50%RH) and 85℃ / 85%RH (96 h) respectively. Dust content was tested according to GB / T 1541-2013 "Determination of dust content in paper and paperboard"; According to GB / T 22899.1-2008 "Determination of wet expansion rate of paper and paperboard - Part 1: Wet expansion rate during the process of increasing maximum relative humidity to 68%" and GB / T 22899.2-2008 "Determination of wet expansion rate of paper and paperboard - Part 2: Wet expansion rate during the process of increasing maximum relative humidity to 86%", the wet expansion rate of samples under normal temperature (25℃ / 50%RH) and 85℃ / 85%RH conditions were tested respectively.

[0100] The test results are shown in Table 1.

[0101] Table 1

[0102] Test results show that: In all embodiments, the peel strength fluctuation range under high temperature and high humidity conditions was controlled within ±12%, and the dust concentration was less than 35 particles / m². 2 The wet expansion rate is less than 0.08%, which fully meets the core performance requirements of electronic carrier paper. Among them, after the addition amount was optimized, Examples 7-9 showed better peel strength stability and dimensional stability, and the wet expansion rate was reduced to a minimum of 0.04%, all of which met the IPC standard.

[0103] Comparative Examples 1, 4, and 5, due to the use of unmodified nanocellulose or improper charge matching, resulted in peel force fluctuations exceeding -23%, moisture expansion rates rising to over 0.13%, and increased dust content. Comparative Example 2, lacking a nano-reinforcement system, experienced a peel force decrease of -37.5% and a moisture expansion rate as high as 0.18%.

[0104] Although Comparative Example 3 showed good peel stability (fluctuation -5.6%), it relied on petroleum-based raw materials. Comparative Examples 6 and 7 respectively verified that the absence of crosslinking agent and neutral sizing agent would lead to a significant increase in peel force fluctuation to over -19% or a doubling of wet expansion rate, confirming the synergistic necessity of the formulation of this invention.

[0105] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An enhanced electronic-carrying paper, characterized by: It includes a base paper layer and a surface adhesive layer attached to at least one surface of the base paper layer, wherein, The base paper layer includes 0.05%-2% cationic nano-reinforcing agent by weight of oven-dry pulp, and the zeta potential of the cationic nano-reinforcing agent is +5~+100 mV; The surface layer includes a bio-based heat-resistant resin and anionic nano-reinforcing agents. The mass percentage of the anionic nano-reinforcing agents in the surface layer is 2%-25%, and the zeta potential of the anionic nano-reinforcing agents is -5 to -100 mV.

2. The reinforced electronic carrier paper according to claim 1, wherein: The cationic nano-reinforcing agent accounts for 0.2%-2% of the oven-dry pulp mass; Alternatively, the mass percentage of anionic nano-reinforcing agents in the surface adhesive layer is 5%-20%; Alternatively, the bio-based heat-resistant resin may comprise 30%-90% of the surface adhesive layer by mass.

3. The reinforced electronic carrier paper according to claim 1, wherein: The cationic nano-reinforcing agent is selected from at least one of cationic cellulose nanoparticles, cationic starch nanoparticles, cationic chitosan nanoparticles, or zwitterionic cellulose nanoparticles; the zwitterionic cellulose nanoparticles are cationic in the base paper layer. Alternatively, the anionic nano-reinforcing agent is selected from at least one of anionic nanocellulose, anionic cellulose nanoparticles, anionic starch nanocrystals, anionic chitosan nanoparticles, or zwitterionic nanocellulose. The zwitterionic nanocellulose is anionic in the surface layer.

4. The enhanced electronic web paper according to claim 1, wherein: The cationic nano-reinforcing agent is cationic nanocellulose, and its Zeta potential is +15~+35 mV; The anionic nano-reinforcing agent is anionic cellulose nanocrystals with a zeta potential of -20 to -40 mV.

5. The reinforced electronic carrier paper according to claim 1, wherein: The bio-based heat-resistant resin is selected from at least one of starch-acrylate graft copolymers, cellulose derivatives grafted with acrylates, lignin-acrylate composite emulsions, vegetable oil-modified acrylic resins, or polylactic acid-based aqueous dispersions.

6. The enhanced electronic web paper according to claim 5, wherein: The acrylate monomer of the bio-based heat-resistant resin is selected from at least one of butyl acrylate, 2-ethylhexyl acrylate, methyl acrylate, ethyl acrylate, isobornyl acrylate, or methyl methacrylate. Alternatively, in the starch-acrylate graft copolymer, the mass ratio of starch matrix to acrylate monomer is 2-4:1; it also includes N-hydroxymethylacrylamide accounting for 0.5%-1.5% of the total mass of the copolymer; Alternatively, the bio-based heat-resistant resin may exist in the form of a main continuous phase, microspheres, or microcapsules.

7. The reinforced electronic carrier paper according to claim 1, wherein: The base material of the paper is selected from at least one of bleached softwood pulp, bleached hardwood pulp, bamboo pulp, straw pulp or waste paper pulp; Alternatively, the mass ratio of bleached softwood pulp to bleached hardwood pulp in the base paper is 15-25:75-85; Alternatively, the base paper may also include 0.6%-1.2% by mass of a neutral sizing agent, which is an alkyl ketene dimer.

8. A process for the production of the reinforced electronic carrier paper according to any one of claims 1 to 7, characterized in that: The process includes the following steps: adding cationic nano-reinforcing agents to pulp to obtain base paper; The coating solution, comprising a bio-based heat-resistant resin and anionic nano-reinforcing agents, is applied to at least one surface of the base paper, and then dried, cured, and calendered to obtain the final product.

9. The method of making a reinforced electronic carrier paper according to claim 8, wherein: The pulp is a mixture of bleached softwood pulp and bleached hardwood pulp, with a freeness of 30-50°SR. Alternatively, the pulp may also include a neutral sizing agent, which is an alkyl ketene dimer.

10. The method of making a reinforced electronic carrier paper according to claim 8, wherein: The coating liquid also includes 0.01%-0.05% by mass of defoamer and 0.05%-0.15% by mass of bactericide.

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