Special glue for transfer paper and preparation method thereof

Abstract

The invention relates to the technical field of adhesives, and discloses special glue for transfer paper and a preparation method thereof.The preparation method comprises the steps that sulfhydrylation ethylene propylene diene monomer and acrylate monomers are mixed, seed emulsion polymerization is initiated, and hybrid emulsion with active sulfydryl sites in the core is prepared; treating the surface of micron silicon dioxide by adopting a silane coupling agent, introducing unsaturated double bonds, and shearing and dispersing an acetylated polyvinyl alcohol aqueous solution and the modified micron silicon dioxide to form slurry; the slurry is added into a hybrid emulsion, the pH value of a system is adjusted to 8.0-8.5, and covalent bonding of micron silicon dioxide particles on the surfaces of emulsion particles is achieved through the addition reaction of sulfydryl and double bonds. And the pinning stability of the particles in a friction environment is ensured.

Description

Technical Field

[0001] This invention relates to a special adhesive for transfer paper and its preparation method, belonging to the field of adhesive technology. Background Technology

[0002] In current transfer paper manufacturing, a back coating composed of polyvinyl alcohol, acrylic emulsion and silica is applied to the back of the paper to maintain printing registration accuracy and waterproof performance. The composition relies on the physical protrusion of inorganic particles on the surface of the film-forming substrate to generate anti-slip friction.

[0003] In high-precision packaging continuous production, transfer paper frequently comes into contact with PVC transparent film or molds containing EPDM rubber sealing components. The acrylate film-forming material has strong polar characteristics, creating an interfacial tension gradient between it and the low surface energy non-polar polymer interface. This causes the shear stress generated by high-speed friction to concentrate at the edges of silica particles. The physical coating system lacks a chemical anchoring mechanism, and frictional heat causes the polymer matrix to soften. Silica particles settle into the matrix or peel off from the embrittled film layer, resulting in loss of anti-slip function and dust pollution. For example, Chinese invention patent CN108149513B discloses transfer paper and its preparation method, which introduces... The conductive components of polyaniline, tin tetrachloride, and graphene are used to construct charge dissipation channels, solving the problem of electrostatic adhesion when transfer paper is stacked. The solution improves the peeling quality of the paper surface. The key technology lies in electrostatic dissipation, which does not involve the micromechanical coupling between the adhesive matrix and the anti-slip filler under dynamic friction conditions. Increasing the resin crosslinking density or increasing the filler ratio to strengthen particle fixation leads to increased coating brittleness and stress cracks caused by high-speed shear impact. The superposition of physical components cannot change the interfacial stress imbalance between the polar adhesive matrix and the physical filler and non-polar contact interface. The preparation method of establishing a chemical affinity layer at the molecular chain level and achieving covalent anchoring of particles is the key to breaking the limitations of physical modification.

[0004] Therefore, how to construct an adhesive system that has interfacial stress dissipation characteristics and enables in-situ pinning of inorganic particles under working conditions has become the technical problem to be solved by this invention. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for preparing a special adhesive for transfer paper, comprising the following steps: Step S1: Thiolized EPDM rubber, deionized water, and 1.5% to 2.5% by mass of a composite emulsifier are mixed and heated to 75 to 82°C. A mixture of monomers consisting of butyl acrylate, methyl methacrylate, and isooctyl acrylate in a mass ratio of 5:3:2 is added dropwise. Seed emulsion polymerization is triggered under the action of ammonium persulfate initiator to obtain a hybrid emulsion with a core-shell structure. The hybrid emulsion has thiolated EPDM rubber as the core and acrylate copolymer as the shell, and the core has active thiol sites. Step S2: Use gamma-methacryloxypropyltrimethoxysilane to treat the surface of micron-sized silica, introducing unsaturated double bond sites on the surface of micron-sized silica. Step S3: An aqueous solution of acetylated polyvinyl alcohol with a solid content of 10.0% to 15.0% and a degree of alcoholysis of 88.0% to 92.0% is mixed with modified micronized silica and subjected to high-shear dispersion at a speed of 2800 to 3500 rpm for 20.0 to 30.0 minutes to obtain a pre-dispersed silica slurry. Step S4: At a stirring speed of 500 to 800 rpm, the pre-dispersed silica slurry is added to the hybrid emulsion. Ammonia is added to adjust the pH of the system to 8.0 to 8.5. Through the addition reaction between active thiol sites and unsaturated double bond sites, micronized silica is covalently bonded to the surface of the hybrid emulsion particles. By weight, the hybrid emulsion is 40.0 to 55.0 parts, the acetylated polyvinyl alcohol aqueous solution is 5.0 to 12.0 parts, the micronized silica is 6.0 to 10.0 parts, the defoamer is 0.1 to 0.3 parts, and the balance is deionized water.

[0006] Preferably, in step S1, the mercapto-modified EPDM rubber has a Mooney scorch index of 5.2 at 100°C, an ethylene mass fraction of 58.0%, and a mercapto mass fraction of 1.2 wt%. In the hybrid emulsion, the mass ratio of mercapto-modified EPDM rubber to acrylate copolymer is 1.5 to 2.2 to 10.0. By limiting the Mooney scorch index and mercapto content of the mercapto-modified EPDM rubber, in step S4, thioether bond anchoring nodes between the hybrid emulsion particles and micron-sized silica are constructed to form an interface reinforcement layer for improving the interface shear strength.

[0007] Preferably, in step S4, the molar ratio of active thiol sites to unsaturated double bond sites is... The following relationship must be satisfied: ,in, This refers to the amount of active thiol groups in the hybrid emulsion. This refers to the amount of unsaturated double bonds on the surface of micron-sized silica, and The value ranges from 1.05 to 1.15, and the addition reaction forms a thioether bond network structure at the interface between micron-sized silica and hybrid emulsion particles.

[0008] Preferably, in the acetylated polyvinyl alcohol aqueous solution in step S3, the average degree of polymerization of the acetylated polyvinyl alcohol is 1700 to 2400; the hydroxyl groups of the acetylated polyvinyl alcohol form hydrogen bond entanglements with the silanol groups on the surface of micronized silica, which, in conjunction with the addition reaction in step S4, achieves directional loading of micronized silica on the surface of the hybrid emulsion particles.

[0009] Preferably, in step S2, the coating layer formed by gamma-methacryloxypropyltrimethoxysilane accounts for 1.2% to 1.5% of the total mass of micron-sized silica; the micron-sized silica is a spherical inorganic filler with an average particle size of 3.5 to 4.5 microns and an oil absorption value of 180 to 220 g / 100 g.

[0010] Preferably, the amount of ammonium persulfate used in step S1 is 0.3% to 0.5% of the total mass of the mixed monomers; the polymerization reaction time in step S1 is 4.0 to 6.0 hours, and the grafting efficiency is controlled by the chain transfer effect of active thiol sites to form a core-shell interface layer that improves interfacial compatibility.

[0011] Preferably, in step S4, the dropping rate of the pre-dispersed silica slurry added to the hybrid emulsion is controlled at 2.0 to 5.0 g / min; the addition reaction is carried out under shear conditions to prevent abnormal thickening of the hybrid emulsion particles and micron-sized silica during covalent bonding.

[0012] Preferably, in the mixed monomers of step S1, butyl acrylate, methyl methacrylate, and isooctyl acrylate are used to construct the shell structure of the adhesive to improve the wettability of the adhesive on the surface of cellulose-based paper.

[0013] Preferably, the defoamer is a polyether-modified silicone defoamer; after adding the defoamer in step S4, the mixture is stirred at 300 rpm for 15.0 to 20.0 minutes to eliminate air bubbles in the reaction system and improve the continuity of the coating film. The resulting adhesive has a solid content of 32.0% to 38.0% and a dynamic viscosity of 150 to 250 mPa·s at 25°C. The adhesive film has elastic recovery properties and is used to improve the interfacial shear strength when the transfer paper contacts the EPDM rubber substrate or polyvinyl chloride material.

[0014] A transfer paper-specific adhesive, which is directly obtained by the preparation method of the transfer paper-specific adhesive.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. In the preparation of the special adhesive, thiol-modified low molecular weight EPDM rubber is introduced. A continuous chemical transition layer is constructed at the interface between the polar cellulose substrate and the non-polar polymer, which reduces the interfacial tension. When the adhesive coating contacts the EPDM rubber or polyvinyl chloride material, the EPDM rubber segments dissipate frictional shear energy through the micro-relaxation effect, avoiding the coating peeling caused by interfacial stress concentration, and improving the bonding stability of the transfer paper under complex working conditions. 2. Unsaturated silane-modified micronized silica undergoes an addition reaction with mercapto groups, covalently anchoring the surface of hybrid emulsion particles to construct elastic suspended anti-slip points. The covalent stitching structure changes the passive deep-buried state of inorganic fillers in the polymer matrix. High-speed friction generates instantaneous high temperature, causing thermal softening of the matrix. Chemical bond forces firmly anchor the silica particles to the coating surface sites, inhibiting particle sedimentation or brittle shedding into the matrix and maintaining a long-term constant friction coefficient. 3. The modified polyvinyl alcohol hydroxyl groups form hydrogen bond entanglements with the silanol hydroxyl groups on the surface of silica, and work together with the covalent stitching structure on the surface of the emulsion particles to make the inorganic particles oriented and distributed at the edges of the hybrid emulsion particles. The combination of physical entanglement and chemical anchoring forms a gear-like micro-topological configuration, which improves the internal compatibility of the coating. During the film formation process, the polymer matrix traps and encapsulates the silica particles, eliminating the dust pollution caused by particle loss during the printing process. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation process of the transfer paper adhesive of this invention. Figure 2 This is a graph showing the relationship between the friction coefficient and particle retention rate under different silica contents according to the present invention. Figure 3 This is a schematic diagram of the microstructure of the hybrid emulsion particles covalently anchored to micron-sized silica according to the present invention. Detailed Implementation

[0017] The present invention will now be described with reference to specific embodiments. It should be noted that the embodiments described herein are for illustration and explanation only and are not intended to limit the scope of protection of the present invention. Any non-substantial modifications or substitutions made by those skilled in the art under the guidance of the present invention should fall within the scope of protection of the present invention.

[0018] This invention provides a transfer paper adhesive and its preparation method, comprising four steps: hybrid emulsion synthesis, inorganic phase modification, pre-dispersed slurry preparation, and covalent synergistic construction. In the preparation process, a hybrid emulsion with a thiolized EPDM rubber core and an acrylate copolymer shell, and active thiol sites in the core, is prepared via seed emulsion polymerization. To guide the arrangement of inorganic particles on the coating surface and increase adhesion strength, this invention utilizes acetylated polyvinyl alcohol to construct a topologically stable network. In practice, an aqueous solution of acetylated polyvinyl alcohol with a solid content of 10% to 20%, a degree of alcoholysis of 90% to 99%, and an average degree of polymerization of 500 to 1700 is weighed and mixed with modified micronized silica. The surface of the micronized silica is treated with a silane coupling agent to introduce unsaturated double bond sites. Then, the acetylated polyvinyl alcohol aqueous solution and the modified micronized silica are dispersed under high shear to obtain a pre-dispersed slurry. Finally, the pre-dispersed slurry is mixed with the hybrid emulsion and adjusted... value to The range is expanded to induce an addition reaction between thiol groups and double bonds, resulting in the covalent bonding of micron-sized silica to the surface of hybrid emulsion particles. Thiol-modified EPDM prefabrication process: [The text abruptly shifts to a different topic] ...Mounney scorch index 30... 60 industrial-grade EPDM rubber is dissolved in cyclohexane solvent to prepare a solution with a mass fraction of 12%. 15% adhesive solution, with 1.2% of the total monomer mass added. 1.5% mercaptoacetic acid and 0.5% azobisisobutyronitrile (AIBN) initiator, nitrogen protection activated, temperature increased to 75°C. The reaction was carried out at 85℃ with stirring at 300 rpm for 4 hours. For 6 hours, thiol groups were introduced into the rubber molecular skeleton through a thiol-olefin radical addition process. After the reaction was completed, anhydrous ethanol was added for precipitation and washing. The filter cake was dried in a vacuum drying oven at 50°C until constant weight. The mass fraction of thiol groups in the product was determined by iodometric titration to ensure that the physical morphology and active site density were adapted to the requirements of seed emulsion polymerization.

[0019] In the high-speed printing environment of transfer paper, the coating comes into dynamic contact with the PVC transparent film or EPDM rubber sealing assembly; due to the interfacial tension gradient between the cellulose paper and the non-polar polymer substrate, interfacial shear stress concentration can lead to coating peeling; to solve this problem, this invention utilizes a hybrid emulsion containing a mercapto-modified EPDM rubber component to adjust the interfacial properties, the specific process being: weighing... Mooney scorch index at ℃ is to ethylene mass fraction is to And the mass fraction of thiol is to Using mercaptolated EPDM rubber as a seed, it was mixed with deionized water and mass fraction to The compound emulsifiers are mixed and heated. ℃ to ℃; Add the mixed monomers dropwise to the system, with a mass ratio of... It is composed of butyl acrylate, methyl methacrylate, and isooctyl acrylate; a seed emulsion polymerization reaction is triggered by ammonium persulfate initiator, the amount of ammonium persulfate being [percentage]% of the total mass of the mixed monomers. to ;reaction Hours to A hybrid emulsion was prepared after hours, wherein the mass ratio of mercapto-modified EPDM rubber to acrylate copolymer was [missing information]. to Compare .

[0020] The instantaneous localized high temperature generated by high-speed friction can cause thermal softening of the polymer matrix, leading to sedimentation or detachment of inorganic anti-slip particles into the matrix. To address this issue, this invention employs a micron-sized silica modification process with a chemical anchoring mechanism. Specifically, gamma-methacryloyloxypropyltrimethoxysilane is used to modify the silica with an average particle size of... to And oil absorption value to The spherical silica is treated to form a coating layer that accounts for a significant portion of the total mass of the micron-sized silica. to This process generates unsaturated double bond sites on the surface of micron-sized silica; this treatment enables inorganic particles to chemically bond with hybrid emulsion particles, transforming physical fillers into covalently anchored anti-slip sites; to guide the arrangement of inorganic particles on the coating surface and increase adhesion strength, this invention utilizes acetylated polyvinyl alcohol to construct a topologically stable network; in practice, a solid content of... to Degree of alcoholysis is to And the average degree of polymerization is to An aqueous solution of acetylated polyvinyl alcohol was mixed with modified micron-sized silica. rpm to High shear dispersion at a rotation speed of rpm minutes to Within minutes, a pre-dispersed silica slurry was prepared; the hydroxyl groups of acetylated polyvinyl alcohol formed hydrogen bond entanglement with the silanol groups on the surface of micron-sized silica, enabling inorganic particles to be directionally mounted on the surface of the emulsion particles.

[0021] In the adhesive integration stage, this invention employs a pinning process based on mercapto-olefin click chemistry to address the problem of unstable particle positioning under dynamic friction; rpm to At a stirring speed of rpm, the pre-dispersed silica slurry was mixed with... to The mixture is added to the hybrid emulsion at a certain speed, and ammonia is added to adjust the system. value to Scope; the addition reaction occurs between the active thiol sites in the core of the hybrid emulsion and the unsaturated double bond sites on the surface of micron-sized silica, and the molar ratio of active thiol groups to unsaturated double bonds... In to Between, that is, satisfying the relational expression ,in, The amount of active thiol groups in the hybrid emulsion is expressed in units of... , This refers to the amount of substance of unsaturated double bonds on the surface of micron-sized silica, expressed in units of... The reaction is carried out under shear conditions, and the resulting thioether bond network structure anchors micron-sized silica on the surface of hybrid emulsion particles, forming a gear-shaped microscopic topological configuration. The prepared transfer paper adhesive consists of the following components by weight: hybrid emulsion. portion to Parts, acetylated polyvinyl alcohol aqueous solution portion to Parts, micron-sized silica portion to Part, polyether-modified silicone defoamer portion to One part, the remainder is deionized water; after adding defoamer, with Stirring at a speed of rpm minutes to minutes; the solid content of the resulting glue is to ,exist The dynamic viscosity at ℃ is to .

[0022] Example 1: In a gravure printing production line, the paper running speed is set to... Its back coating undergoes dynamic friction with the polyvinyl chloride acceptor membrane, which has low surface energy characteristics; the heat generated by the friction causes the roller temperature to rise to [a certain level]. At temperatures above ℃, the acrylate components in the coating soften, causing the silica particles, which were originally physically coated, to settle into the coating under interfacial shear stress. This results in a loss of surface friction and printing misregistration. The special adhesive provided in this invention is used for coating, with the solid content of the adhesive adjusted to [specific value missing]. The mixture is then coated onto a paper substrate using a coating roller and dried to form a film. In the thermal field generated by dynamic friction, the mercapto-modified EPDM rubber in the hybrid emulsion core maintains its physical morphology and elastic modulus. Furthermore, due to the interaction between the unsaturated double bond sites on the surface of micron-sized silica and the active mercapto sites in the hybrid emulsion particle core... Value An addition reaction occurs under alkaline conditions, with the molar ratio of active thiol groups to unsaturated double bonds... Set as This ratio satisfies the formula ,in The amount of active thiol groups in the hybrid emulsion is expressed in units of... , This refers to the amount of substance of unsaturated double bonds on the surface of micron-sized silica, expressed in units of... This chemical anchoring mechanism enables micron-sized silica to gain site support within a heat-softened acrylate matrix, thereby inhibiting inward particle displacement during continuous production line operation. Within a monitoring period of minutes, the static friction coefficient of the paper coating surface remained stable at... to No dust pollution caused by particle peeling occurred during the process; micron-sized silica was fixed to the coating surface by the covalent attraction of sulfide bonds, maintaining a constant tension state of the transfer paper during rewinding, and controlling the printing registration accuracy deviation within a certain range. Within.

[0023] Example 2: To verify the particle positioning stability of the transfer paper adhesive under dynamic friction conditions, a high-frequency contact friction test procedure was established; the test used a physical testing platform simulating a gravure printing roller, which has... to The linear velocity adjustment range and the temperature control error are stable within Within ℃, the data source comes from the normal pressure and tangential friction force signals collected by the sensor, and the sampling frequency is set to [value missing]. To capture stress fluctuations under high-speed friction; core parameters in the experiment The value depends on the addition kinetics of thiol groups and unsaturated double bonds in an aqueous environment, and the trade-off between suppressing the hydrolysis rate of siloxanes and inducing the efficiency of thiol nucleophilic attack. Value to At this time, the decrease in protonation promotes the formation of sulfide anions, thus enabling the addition reaction to maintain a high conversion rate under room temperature shear conditions. This experiment selected... Value As a typical value; to simulate interference from the industrial environment, a substance with... is introduced onto the surface of the paper substrate. Randomly fluctuating interfacial tension noise is used to assess the adaptability of the adhesive to paper surfaces with different polarities.

[0024] The experiment was divided into five groups to construct a multi-dimensional control system. The experimental groups used the formulation of the aforementioned specific implementation method, namely the hybrid emulsion. Parts, acetylated polyvinyl alcohol aqueous solution Parts, micron-sized silica share and Value Control group 1 removed the mercapto-modified EPDM rubber and physically mixed it with an equal mass of acrylate emulsion and micron-sized silica; Control group 2 maintained the formulation components but added [something] during the mixing stage. Value adjusted to To block the covalent bonding process; the control group 3 was set with a silica addition amount of [missing value]. The amount was lower than the lower limit of the scope defined in this invention; the control group 4 was set with a micron-sized silica addition amount of [missing information]. The amount exceeds the upper limit of the scope defined in this invention; all five groups of adhesives are within... Operating at roller speed The effectiveness of the technology was evaluated by measuring the dynamic friction coefficient and particle retention rate of the coating surface over a period of time.

[0025] Table 1: Example Table of Frictional Stability and Particle Positioning Data for Different Groups

[0026] Analysis of the test data recorded in Table 1 shows that the test group maintained frictional stability after operation, and its particle retention rate reached [percentage missing]. This confirms that the thioether bond network established on the surface of hybrid emulsion particles based on the thiol-olefin addition mechanism can resist the matrix softening effect caused by frictional heating; the friction coefficients of control groups 1 and 2 decreased in the later stage of operation, and the measured values ​​dropped to and Electron microscopy revealed that micron-sized silica underwent mechanical sedimentation into the matrix, indicating that physical encapsulation could not achieve site pinning of particles under heated conditions; data from control group 3 showed that when the micron-sized silica content was lower than At this point, the initial coefficient of friction is only It cannot provide sufficient anti-slip resistance; although the initial friction coefficient of control group 4 is higher, its particle retention rate drops to a lower level. This is because excessive inorganic particles cause localized stress concentration in the topologically stable network constructed by acetylated polyvinyl alcohol, leading to coating peeling.

[0027] Example 3: This example combines Figures 1 to 3 This describes a special adhesive for transfer paper and its preparation method, such as... Figure 1 As shown, the process begins with raw material component A, namely mercapto-modified EPDM rubber and acrylate monomers. In step S1, intermediate I hybrid emulsion with active mercapto sites and a core-shell structure is prepared through seed emulsion polymerization. Simultaneously, raw material component B, namely micron-sized silica and silane coupling agent, undergoes surface chemical modification in step S2 to introduce unsaturated double bond sites. Then, acetylated polyvinyl alcohol aqueous solution is added to the system, and physical dispersion is achieved through high shear dispersion in step S3 to form intermediate II pre-dispersed silica slurry containing unsaturated double bonds and PVA dispersion phase. Finally, intermediate I and intermediate II are mixed and enter the covalent assembly stage of the system in step S4. The pH value of the system is adjusted to the range of 8.0 to 8.5 by adding ammonia water to trigger the addition reaction of mercapto and double bonds, and finally, a transfer paper adhesive product is formed with micron-sized silica covalently bonded to the surface of emulsion particles.

[0028] like Figure 2 As shown in the figure, the horizontal axis represents the silica content (parts), the left vertical axis corresponds to the friction coefficient, and the right vertical axis corresponds to the particle retention rate (%). The experimental data curves show that as the silica content increases from 2 parts to 16 parts, both the initial friction coefficient (shown by the solid line) and the friction coefficient after operation (shown by the dashed line) show a trend of first increasing and then decreasing, reaching a peak at 10 parts. The particle retention rate (shown by the dotted line) reaches a maximum of 98% at 10 parts, but after the content exceeds 12 parts, due to local stress concentration in the system's topology, the particle retention rate decreases sharply, dropping to 65% at 16 parts. Figure 3 As shown, the prepared transfer paper adhesive exhibits a regular core-shell topology. The core of its hybrid emulsion particles is a thiolized EPDM rubber containing active -SH thiol sites, and the outer layer is coated with an acrylate copolymer as the shell. Micron-sized silica particles with an average particle size of 3.5 μm to 4.5 μm are distributed on the surface of the emulsion particles. Through the CSC thioether bonds formed by the addition reaction shown by the dashed line in the figure, the silica particles are covalently anchored to the active thiol sites in the core. Combined with the hydrogen bond entanglement structure between the silica particles and the acrylate shell shown by the fine dotted line in the figure, the anti-slip particles are firmly anchored at the microscopic level.

[0029] Example 4: In the application development scenario of ultrathin PVC polymer film transfer, the back coating layer experiences micro-stress concentration under tensile stress, causing the inorganic anti-slip particles in the physical blending system to drift. To determine the optimal site density of thiol groups in thiolized EPDM rubber, a parameter calibration method based on core-shell regularity monitoring was established. An initial thiol mass fraction was selected. They are respectively , as well as Three gradient samples were compared; during the seed emulsion polymerization stage, the dropping rate of the mixed monomers was increased. Set as to The range, this rate is determined based on the kinetic balance between the diffusion rate of monomers on the rubber core surface and the chain growth rate; if the dropping acceleration rate Exceed Excessive local concentration of monomers in the system can induce monomer self-polymerization and generate isolated acrylate particles, reducing the encapsulation integrity of the hybrid emulsion; when the dropping rate... for and for At that time, the acrylate copolymer forms a thickness of [missing information] on the surface of the mercapto-modified EPDM rubber. to A uniform shell, with the exposure rate of active thiol groups in the core at a certain level. above.

[0030] During the adhesive integration stage, the chemical pinning density of micron-sized silica is quantitatively calibrated by adjusting... Value to The formation of thioether bonds was induced, and the rheological behavior during shearing was monitored using an online viscometer; the molar ratio of active thiol groups to unsaturated double bonds was adjusted. Set at At that time, the covalent loading efficiency of micron-sized silica on the surface of emulsion particles is at its maximum; the molar ratio of active thiol groups to unsaturated double bonds is... Satisfy the following formula ,in The molar ratio, The amount of active thiol groups in the hybrid emulsion is expressed in units of... , This refers to the amount of substance of unsaturated double bonds on the surface of micron-sized silica, expressed in units of... Cross-sectional scanning analysis of the cured coating revealed that micron-sized silica with an average spacing of [missing information]. The topological configuration is anchored to the surface of the hybrid emulsion particles; in the peel strength test, the peel force between the coating with the above calibration parameters and the low surface energy substrate is determined by the physical blending system. Upgraded to In simulation High-frequency vibration and In dynamic strain fatigue testing, the particle center displacement deviation is controlled within Within; data show that by controlling the thiol content and monomer drop rate, the inorganic phase and the elastic organic core are chemically stitched together, and the acetylated polyvinyl alcohol network shares the shear stress at a local level.

[0031] Example 5: In continuous production involving multiple batch material switching, the mass fraction of thiol groups in different batches of thiolized EPDM rubber varies. Fluctuations exist, in order to maintain the molar ratio of active thiol groups to unsaturated double bonds. In Before each batch of hybrid emulsion synthesis, the active site calibration method of the raw materials is performed, and the actual mass fraction of active thiol groups in the thiolized EPDM rubber is determined by potentiometric titration. And substitute this value as an input variable into the relation. Among them The amount of active thiol groups in the hybrid emulsion is expressed in units of... , This refers to the amount of substance of unsaturated double bonds on the surface of micron-sized silica, expressed in units of... The amount of added micron-sized silica was adjusted based on the calculated results. This ensures that the surface of each batch of hybrid emulsion particles has a consistent density of chemical reaction sites.

[0032] When the system is applied to factory environments with different industrial water source conditions, the initial pH difference of deionized water will change the formation kinetics of thioether bonds. Therefore, an on-site benchmark calibration method is introduced before preparing the pre-dispersed silica slurry, utilizing measurement accuracy of... The online monitoring meter determines the initial value of the dilution system, and adds a concentration of [value] to the system at a uniform rate according to the preset acid-base titration curve. The ammonia solution, after mixing the hybrid emulsion with the pre-dispersed silica slurry, causes an instantaneous... Value locked at At this point, the dynamic viscosity rise rate of the system, as monitored by an online rotational viscometer, is at [a certain value]. to Within the specified range, this indicates that the mercapto-olefin click reaction has entered a controlled growth stage, and the chemically loaded mass fraction of micron-sized silica on the surface of the hybrid emulsion is stable at a certain level. Place.

[0033] Example 6: In the scenario of geometric distribution calibration for the back coating of high-precision gravure printing, the average particle size of hybrid emulsion particles Compared with the average particle size of micron-sized silica The matching relationships were determined using a standardized topological association method, and the average particle size of the hybrid emulsion particles in the current batch was measured using a dynamic light scattering instrument. Used to adjust the spatial loading efficiency of micron-sized silica on the surface of hybrid emulsion particles, particle size matching coefficient Set at to Within the range, particle size matching coefficient Satisfy the calculation relationship ,in, The average particle size of silica is in micrometers, in units of 100 micrometers. , The average particle size of the hybrid emulsion particles is given in units of 100 μm. By adjusting the mass fraction of the composite emulsifier in the seed emulsion polymerization stage ,when exist to When the range changes, Presented by Reduce to The trend is used to determine the amount of emulsifier that meets the geometric arrangement requirements, so that a uniformly distributed topological matrix is ​​formed on the surface of the cured coating. When the system faces ambient temperature... When dynamic offset conditions are caused by fluctuations, the induction period of the addition reaction between thiol groups and unsaturated double bonds changes with the frequency of molecular thermal motion. To maintain a consistent thioether bond network stitching density under different operating conditions, a temperature-sensing-based on-site compensation method is implemented during the adhesive integration stage, utilizing measurement accuracy of... Temperature of the sensor acquisition system at ℃ When detected Deviation When the standard reference value of ℃ is reached, the amount of ammonia added is finely adjusted by the feeding system to ensure the instantaneous temperature of the system is within a certain range. The value is calculated according to the compensation formula. To perform dynamic response, where For the adjusted target value, The measured ambient temperature is in °C. This method adjusts the reaction rate fluctuations caused by thermal disturbances to stabilize the chemically loaded mass fraction of micron-sized silica on the surface of hybrid emulsion particles. Place.

[0034] In scenarios adapting to cellulose paper substrates with different dynamic moduli, the mass ratio of mercapto-modified EPDM rubber to acrylate copolymer in the hybrid emulsion is... Calibration is performed based on the energy dissipation coefficient of the substrate, when the mass ratio Below At that time, the distribution density of the elastic rubber core was insufficient to provide interfacial site support, resulting in micron-sized silica... The particle retention rate decreased to [value] under friction conditions at ℃. When the mass ratio Exceed At that time, the cohesive strength of the acrylate continuous phase in film formation is impaired, and the coating... Peel strength decreases to at ℃ And the haze of the film exceeds By implementing a balance between peeling force and particle displacement, the mass ratio is... Determined as At this point, the coating achieves interfacial stress dissipation while maintaining high transparency. When the system is applied to a high-humidity production environment, the mass fraction of acetylated polyvinyl alcohol aqueous solution... Adjustments need to be made based on the ambient water vapor partial pressure, when the mass fraction Below When the concentration reaches a certain level, the kinetic stability of the pre-dispersed silica slurry decreases, and the micron-sized silica... The settling volume ratio reached within hours This results in uneven distribution of anti-slip spots on the back coating, and when the mass fraction... Exceed When the glue is applied, The dynamic viscosity at ℃ increases to The above exceeds the shear load boundary of the gravure coating roller. To determine the mass fraction, a cross-calibration method based on viscosity and settling rate is performed before on-site deployment. Set as This method ensures the stability of the adhesive's rheological behavior during continuous operation.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a special adhesive for transfer paper, characterized in that, Includes the following steps: Step S1: Thiolized EPDM rubber, deionized water, and 1.5% to 2.5% by mass of a composite emulsifier are mixed and heated to 75 to 82°C. A mixture of monomers consisting of butyl acrylate, methyl methacrylate, and isooctyl acrylate in a mass ratio of 5:3:2 is added dropwise. Seed emulsion polymerization is triggered under the action of ammonium persulfate initiator to obtain a hybrid emulsion with a core-shell structure. The hybrid emulsion has thiolated EPDM rubber as the core and acrylate copolymer as the shell, and the core has active thiol sites. Step S2: Use gamma-methacryloxypropyltrimethoxysilane to treat the surface of micron-sized silica, introducing unsaturated double bond sites on the surface of micron-sized silica. Step S3: An aqueous solution of acetylated polyvinyl alcohol with a solid content of 10.0% to 15.0% and a degree of alcoholysis of 88.0% to 92.0% is mixed with modified micronized silica and subjected to high-shear dispersion at a speed of 2800 to 3500 rpm for 20.0 to 30.0 minutes to obtain a pre-dispersed silica slurry. Step S4: At a stirring speed of 500 to 800 rpm, the pre-dispersed silica slurry is added to the hybrid emulsion, and ammonia is added to adjust the pH of the system to 8.0 to 8.

5. Through the addition reaction between active thiol sites and unsaturated double bond sites, micron-sized silica is covalently bonded to the surface of the hybrid emulsion particles. By weight, the mixture comprises 40.0 to 55.0 parts of hybrid emulsion, 5.0 to 12.0 parts of acetylated polyvinyl alcohol aqueous solution, 6.0 to 10.0 parts of micronized silica, 0.1 to 0.3 parts of defoamer, and the balance being deionized water.

2. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S1, the mercapto-modified EPDM rubber has a Mooney scorch index of 5.2 at 100°C, an ethylene mass fraction of 58.0%, and a mercapto mass fraction of 1.2 wt%. In the hybrid emulsion, the mass ratio of mercapto-modified EPDM rubber to acrylate copolymer is 1.5 to 2.2 to 10.

0. By limiting the Mooney scorch index and mercapto content of the mercapto-modified EPDM rubber, in step S4, thioether bond anchoring nodes between the hybrid emulsion particles and micron-sized silica are constructed to form an interface reinforcement layer for improving the interfacial shear strength.

3. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S4, the molar ratio of active thiol sites to unsaturated double bond sites... The following relationship must be satisfied: ,in, This refers to the amount of active thiol groups in the hybrid emulsion. This refers to the amount of unsaturated double bonds on the surface of micron-sized silica, and The value ranges from 1.05 to 1.15, and the addition reaction forms a thioether bond network structure at the interface between micron-sized silica and hybrid emulsion particles.

4. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S3, the acetylated polyvinyl alcohol aqueous solution has an average degree of polymerization of 1700 to 2400. The hydroxyl groups of the acetylated polyvinyl alcohol form hydrogen bond entanglements with the silanol groups on the surface of micronized silica, which, in conjunction with the addition reaction in step S4, achieves directional loading of micronized silica on the surface of the hybrid emulsion particles.

5. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S2, the coating layer formed by gamma-methacryloxypropyltrimethoxysilane accounts for 1.2% to 1.5% of the total mass of micron-sized silica; the micron-sized silica is a spherical inorganic filler with an average particle size of 3.5 to 4.5 microns and an oil absorption value of 180 to 220 g / 100 g.

6. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S1, the amount of ammonium persulfate is 0.3% to 0.5% of the total mass of the mixed monomers; the polymerization reaction time in step S1 is 4.0 to 6.0 hours, and the grafting efficiency is controlled by the chain transfer effect of active thiol sites to form a core-shell interface layer that improves interfacial compatibility.

7. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S4, the dropping rate of the pre-dispersed silica slurry added to the hybrid emulsion is controlled at 2.0 to 5.0 g / min; the addition reaction is carried out under shear conditions to prevent abnormal thickening of the hybrid emulsion particles and micron-sized silica during covalent bonding.

8. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, In step S1, butyl acrylate, methyl methacrylate, and isooctyl acrylate are used to construct the shell structure of the adhesive to improve the wettability of the adhesive on the surface of cellulose-based paper.

9. The method for preparing a transfer paper adhesive according to claim 1, characterized in that, The defoamer is a polyether-modified silicone defoamer; after adding the defoamer in step S4, continue stirring at 300 rpm for 15.0 to 20.0 minutes to eliminate bubbles in the reaction system and improve the continuity of the coating film. The resulting adhesive has a solid content of 32.0% to 38.0% and a dynamic viscosity of 150 to 250 mPa·s at 25°C. The adhesive film has elastic recovery properties and is used to improve the interfacial shear strength when transfer paper contacts EPDM rubber substrate or polyvinyl chloride material.

10. A special adhesive for transfer paper, characterized in that, The transfer paper adhesive is obtained directly by the preparation method of the transfer paper adhesive described in claim 1.

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