Adhesive for printing forming as well as use method and application of adhesive

Abstract

The invention discloses an adhesive for printing forming. The adhesive is prepared from the following components: core-shell structure microspheres, a nanocellulose reinforcement phase, a photothermal conversion agent and a rheology modifier, the inner core of the core-shell structure microsphere is paraffin, and the outer shell of the core-shell structure microsphere is acrylate; the mass fraction of the nano cellulose reinforced phase is 0.5 to 1.2 wt%; the mass fraction of the photothermal conversion agent is 3-5 wt%; the mass fraction of the rheology modifier is 0.5 to 1.0 weight percent. According to the adhesive disclosed by the invention, the acrylate is taken as a shell, the paraffin is taken as a core to form a unique core-shell structure microsphere, and the structure is mutually matched with a nanocellulose reinforced phase, so that cold-state printing and thermal activation bonding can be realized, and the problem that the precision and the strength of a traditional adhesive cannot be obtained at the same time is solved; the adhesive can be applied to the field of book binding, and the binding thickness can be reduced; the adhesive can also be applied to the field of packaging, and the adhesive can be activated again in a heating mode and the like, so that reversible sealing is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and more particularly to a printing adhesive and a use method and application thereof. Background Art

[0002] Traditional adhesives are widely used in various fields, including bookbinding, packaging, and sealing. However, they still face numerous limitations in practical use. For example, in bookbinding, traditional latex adhesives are typically applied at a thickness of 50-100μm, resulting in thick, unsightly adhesive layers on bound books. Furthermore, they cannot meet the requirements of high-precision binding and are difficult to print on complex adhesive lines. Another example is that in the packaging industry, conventional adhesives struggle to achieve reversible sealing, preventing effective resealing after opening.

[0003] The performance of traditional adhesives determines that they cannot achieve lightweight binding and reversible sealing, and it is necessary to break through the existing formula and find new adhesives. Summary of the Invention

[0004] In response to the above-mentioned technical problems, the present invention provides a printable adhesive and its use method and application. The adhesive uses acrylic ester as the shell and paraffin as the core to form a unique core-shell structure microsphere. This structure cooperates with the nanocellulose reinforcement to achieve cold printing and heat-activated bonding, thereby overcoming the problem that traditional adhesives cannot achieve both precision and strength.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] A printable adhesive comprises the following components: core-shell microspheres, a nanocellulose reinforcement phase, a photothermal conversion agent, and a rheology modifier; the core of the core-shell microspheres is paraffin, and the shell of the core-shell microspheres is acrylate; the mass fraction of the nanocellulose reinforcement phase is 0.5-1.2wt%; the mass fraction of the photothermal conversion agent is 3-5wt%; and the mass fraction of the rheology modifier is 0.5-1.0wt%.

[0007] Furthermore, the particle size distribution D50 of the core-shell structured microspheres is 1.8 microns.

[0008] Furthermore, the nanocellulose reinforcement phase is oxidized nanocellulose with an aspect ratio greater than 100.

[0009] Furthermore, the light-to-heat conversion agent is copper phthalocyanine.

[0010] Furthermore, the rheology modifier is hydrophobically modified fumed silica.

[0011] Furthermore, the mass fraction of the nanocellulose reinforcement phase is 0.8-1.0 wt%;

[0012] The mass fraction of the photothermal conversion agent is 3.5-4.5wt%;

[0013] The mass fraction of the rheology modifier is 0.6-0.8 wt%.

[0014] A method for using a printed adhesive, comprising:

[0015] Cold printing: printing and applying the adhesive to the location to be pasted at a first temperature; the first temperature is lower than the phase transition temperature of paraffin wax, which is 25-40°C;

[0016] Thermally activated bonding: At the second temperature, the core of the core-shell structure microspheres is melted to achieve dynamic bonding; the peel strength of the adhesive after thermal activation is ≥12N / cm 2 , error ±0.5N / cm 2 ; The second temperature is higher than the phase transition temperature of paraffin, which is 65-100°C.

[0017] Furthermore, in the heat activated bonding stage, the temperature is raised to a second temperature by laser heating.

[0018] The invention discloses an application of a printed adhesive, wherein the adhesive is used in the field of bookbinding.

[0019] The invention discloses an application of a printed adhesive, wherein the adhesive is used in the field of intelligent packaging.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present application creatively proposes an adhesive system in which core-shell structured microspheres and nanocellulose reinforcement phases cooperate with each other. The core-shell structured microspheres have acrylate as the outer shell and paraffin as the inner core. This structural design gives the adhesive special performance changes at different temperatures; at the same time, the nanocellulose reinforcement phase can form a three-dimensional network structure in the adhesive, enhance the cohesion and overall performance of the adhesive, and improve the mechanical strength and stability of the adhesive; the rheology regulator can effectively adjust the rheological properties of the adhesive, so that it has good fluidity and thixotropy during the printing process, ensuring the uniformity and stability of the printed layer; the photothermal converter can achieve rapid heating, accurately control the activation process of the adhesive, and improve the bonding efficiency; the present application can achieve the effect of printing at low temperature and bonding at high temperature through the combination of the above components, which can not only ensure the bonding accuracy of the adhesive, but also ensure the bonding strength of the adhesive, solving the problem that traditional adhesives cannot have both accuracy and strength.

[0021] Based on the above-mentioned cold printing and hot bonding characteristics, the adhesive of the present application can be used in the field of book binding to reduce the binding thickness; it can also be used in the field of packaging, and the adhesive can be reactivated by heating and other methods to achieve reversible sealing. DETAILED DESCRIPTION

[0022] The following examples are intended to illustrate the present invention but are not intended to limit the scope of the present invention. Modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the present invention are intended to be within the scope of protection of the present invention. Unless otherwise specified, the experimental materials, reagents, and instruments used in the examples of the present invention are commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0023] This application provides a printable adhesive comprising the following components: core-shell microspheres, a nanocellulose reinforcement phase, a photothermal conversion agent, and a rheology modifier. The nanocellulose reinforcement phase has a mass fraction of 0.5-1.2 wt%, preferably 0.8-1.0 wt%; the photothermal conversion agent has a mass fraction of 3-5 wt%, preferably 3.5-4.5 wt%; and the rheology modifier has a mass fraction of 0.5-1.0 wt%, preferably 0.6-0.8 wt%.

[0024] Among them, the inner core of the core-shell structure microsphere is paraffin wax, and the outer shell of the core-shell structure microsphere is acrylate. The phase transition temperature of paraffin wax is 65°C; that is, in an environment below the phase transition temperature, paraffin wax is solid, and in an environment above the phase transition temperature, paraffin wax is liquid. This application sets the phase transition temperature of paraffin wax to 65°C to balance low-temperature printing stability and high-temperature bonding efficiency. Based on this phase change, the core-shell structure microspheres can give the adhesive special performance changes at different temperatures. Specifically, when the adhesive is in a high-temperature environment, after the paraffin wax melts, the close bonding between its own molecules is broken, the intermolecular force is weakened, and the fluidity is significantly enhanced. This change in fluidity will affect the structure and interaction inside the adhesive. The relatively stable structure originally formed by solid paraffin wax and other components is destroyed, the factors that hinder the flow of the adhesive are reduced, and the friction resistance between the components in the adhesive is reduced, so that the adhesive as a whole exhibits the characteristics of decreased viscosity and enhanced fluidity, which is conducive to adhesion.

[0025] The acrylic shell has a relatively high hardness, specifically 72 Shore D. During the adhesive printing and coating process, it can provide mechanical strength to the entire adhesive system, allowing the adhesive to be stably adhered to the object to be adhered. In this way, the thickness of the adhesive printing and coating can be precisely controlled.

[0026] Due to the characteristics of the core-shell microspheres, this application can be printed and coated at low temperatures, while achieving adhesive adhesion at high temperatures. Because the adhesive has a certain mechanical strength and low fluidity at low temperatures, thinner printing and coating can be achieved. Specifically, the adhesive in this application can achieve a printing and coating thickness of 2 microns. Furthermore, due to the high fluidity of the adhesive at high temperatures, when the ambient temperature is higher than the phase transition temperature of paraffin wax, the paraffin wax melts, triggering a plasticizing effect that reduces the viscosity of the adhesive by three orders of magnitude, facilitating infiltration and bonding.

[0027] The plasticizing effect refers to the phenomenon that under certain conditions, a substance changes its physical properties, plasticity and flexibility, and viscosity decreases due to the addition of plasticizers or changes in its own internal composition. In the adhesive of the present application, when the temperature reaches 65°C, the paraffin core melts and triggers a plasticizing effect. After the paraffin melts, its molecular state changes from an ordered arrangement in the solid state to a disordered state in the liquid state, the intermolecular force weakens, and the fluidity increases. This change increases the overall plasticity and flexibility of the adhesive, which is manifested as a decrease of 3 orders of magnitude in viscosity, making it easier to spread and infiltrate the surface of the bonded material, thereby achieving a better bonding effect.

[0028] As a specific embodiment, the particle size distribution of the core-shell structure microspheres in the present application is D50=1.8 μm.

[0029] The nanocellulose reinforcement phase in the present application is an oxidized nanocellulose with an aspect ratio greater than 100, specifically TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl free radical) oxidized nanocellulose. In the case of a relatively low addition amount, TEMPO oxidized nanocellulose can form a three-dimensional network with a large storage modulus (storage modulus G'>10 4 Pa), which can enhance the cohesion and overall performance of the adhesive and improve its mechanical strength and stability.

[0030] The photothermal conversion agent in this application is near-infrared absorbing copper phthalocyanine. The absorption rate of copper phthalocyanine for 808nm laser is greater than 95%, that is, copper phthalocyanine has high laser absorption characteristics and can realize selective laser heating. During the laser absorption process, the heating rate is greater than 200℃ / s, providing an efficient and precise way to activate the adhesive.

[0031] The rheology modifier in this application is hydrophobically modified fumed silica, and the thixotropy index (TI) of hydrophobically modified fumed silica is 4.8-5.2, which can effectively adjust the rheological properties of the adhesive, so that it has good fluidity and thixotropy during the printing process, ensuring uniform printing and stable adhesive layer thickness.

[0032] This application creatively proposes to combine core-shell structured microspheres (acrylate shell / paraffin core) with nanocellulose reinforcement to form an intelligent adhesive with dynamic bonding properties. The phase transition point of the core-shell microspheres is precisely controlled at 65°C, which can achieve the dual functions of cold printing and heat-activated bonding. At the same time, this application uses near-infrared absorbing copper phthalocyanine as a photothermal conversion agent. The absorption rate of near-infrared absorbing copper phthalocyanine under 808nm laser is greater than 95%, which can achieve local rapid heating (heating rate > 200°C / s), solving the problems of high energy consumption and slow response of traditional heat-activated adhesives.

[0033] During the cold printing process, paraffin wax is in a solid state, acrylate provides a certain mechanical strength to the adhesive, the nanocellulose reinforcing phase enhances the stability of the adhesive, and the rheology regulator gives the adhesive good fluidity and thixotropy. Through the synergistic effect of the three, the adhesive can be evenly and stably coated on the adhesive article through the printing process when the ambient temperature is lower than the phase change temperature of paraffin wax, thereby making the printing thickness uniform and controllable. Specifically, the present application can control the printing thickness to be around 2 microns.

[0034] During the heat-activated bonding process, the photothermal converter can quickly absorb the laser and cause the adhesive to heat up quickly, improving the bonding efficiency. At the same time, the core-shell microspheres induce a plasticizing effect at high temperatures, causing the adhesive viscosity to drop by three orders of magnitude, making it easier to spread and infiltrate the surface of the bonded material, thereby achieving a better bonding effect. After the heat-activated bonding is completed, the adhesive printed with a thickness of 2 microns in this application has a peel strength of ≥12N / cm measured under the JIS K6854 standard. 2 ; Error range ±0.5N / cm 2 .

[0035] The plasticizing effect in this application is caused by the melting of paraffin (phase change), which causes the viscosity of the adhesive to drop by 3 orders of magnitude (from 10 5 mPa·s down to 10 2 mPa·s), significantly improving the fluidity and wettability of the adhesive. This patented plasticizing effect is achieved through dynamic viscosity regulation via paraffin phase transition, making it both reversible and environmentally friendly.

[0036] In summary, the adhesive of this application has the following advantages:

[0037] (1) A composite formula of core-shell microspheres and nanocellulose reinforcement is used to achieve cold printing (2μm accuracy) and heat-activated bonding (viscosity drops by 3 orders of magnitude), breaking through the limitation of traditional adhesives that cannot achieve both high precision and strong bonding.

[0038] (2) By improving the adhesive formula, the bonding process was improved. The adhesive was applied through the printing process. In combination with the printing parameters, precise folding and bonding with a curvature radius of ≤1mm can be achieved.

[0039] (3) During the heat-activated bonding process, laser heating is used to increase the temperature, achieving local rapid heating (heating rate > 200°C / s), which solves the problems of high energy consumption and slow response of traditional heat-activated adhesives.

[0040] The adhesive described herein can be prepared by adding core-shell microspheres, a nanocellulose reinforcement phase, a photothermal conversion agent, and a rheology modifier in a clean reaction vessel in the appropriate proportions, stirring at 500-800 rpm for 2-3 hours to ensure uniform dispersion of the ingredients. The nanocellulose reinforcement phase comprises 0.5-1.2 wt% of the adhesive; the photothermal conversion agent comprises 3-5 wt% of the adhesive; and the rheology modifier comprises 0.5-1.0 wt% of the adhesive.

[0041] The present application provides a method for using a printed adhesive, comprising:

[0042] S1: Cold printing: At a first temperature, the adhesive is printed and applied to the location to be pasted; the first temperature is less than 65°C (about 25-40°C in actual operation) to ensure the stability of cold printing.

[0043] In specific implementation, the ink roller temperature during cold printing is set to 25±1°C, and the ambient temperature is controlled below 40°C (such as the drying condition is 40°C hot air) to ensure that the paraffin remains solid and the adhesive maintains stability and printing accuracy (2μm thickness).

[0044] During the cold printing process, the core-shell microsphere shell and the nanocellulose reinforcement work together to maintain the adhesive's shape and stability, facilitating precise printing. Printing is performed using 2400dpi CTP platemaking technology, with the following offset press settings: ink roller temperature: 25±1°C; printing pressure: 0.15-0.18MPa; drying conditions: 40°C hot air (8m / s wind speed).

[0045] This application uses 2400dpi CTP platemaking technology and specific offset printing machine parameters to achieve precise pattern printing of 2μm ultra-thin film layers (error ±0.3μm), which is unprecedented in the adhesive field and greatly improves the application accuracy and range of adhesives.

[0046] S2: Heat-activated pasting: At the second temperature, the core of the core-shell structure microspheres is melted to achieve dynamic bonding; the second temperature is greater than 65°C (quickly reached by laser, about 65-100°C in actual operation) to achieve heat-activated bonding. The core difference between the first temperature and the second temperature is whether it crosses the phase change temperature of paraffin wax (65°C), thereby controlling the printing and bonding behavior of the adhesive respectively. In a specific implementation, the photothermal converter (phthalocyanine copper) is irradiated with an 808nm laser to rapidly heat the adhesive to above 65°C (heating rate > 200°C / s), triggering the melting of paraffin wax and inducing a plasticizing effect to achieve bonding.

[0047] After the application is heat activated and pasted, the peel strength is measured under the JIS K6854 standard ≥12N / cm 2 ; Error range ±0.5N / cm 2 ; Can achieve the dual requirements of printing accuracy and bonding strength.

[0048] The present application provides an application of a printed adhesive in the field of bookbinding, for example, it can be used for precision bookbinding. The adhesive provided in the present application can achieve a 2μm ultra-thin film layer (error ±0.3μm), and the peel strength measured under the JIS K6854 standard is ≥12N / cm 2 ; Error range ±0.5N / cm 2 , and at the same time, it has achieved a breakthrough in precision folding processing with a curvature radius of ≤1mm.

[0049] For example, it can be used for special-shaped locking technology; the adhesive provided in this application can achieve 60° flat binding by printing spiral adhesive lines (line width 0.2mm), which improves the user experience and aesthetics of the book, while reducing the production cost of hardcover books by 28%, bringing a new production model to the printing and binding industry.

[0050] In bookbinding applications, the prepared adhesive is loaded into an offset printing press, and a spiral glue line is printed on the book page according to the set parameters. After printing, the glue line area is irradiated with an 808nm laser while the ambient temperature is controlled at around 65°C to achieve rapid bonding.

[0051] The present application provides an application of a printed adhesive in the field of smart packaging. For example, it can be used in the field of reversible packaging to realize a reversible sealing structure in the smart packaging system, so that the package can be sealed again after opening, thereby improving the practicality and environmental friendliness of the packaging.

[0052] Specifically, adhesive is printed at the predetermined sealing position of the packaging material to form a reversible sealing area. When the package is opened, the adhesive is reactivated by heating or other means to achieve resealing, thereby improving the practicality and environmental friendliness of the packaging.

[0053] This application provides a printed adhesive that, after use, can be separated from waste adhesive using ultrasonic-assisted separation technology, with a separation efficiency exceeding 98%. This effectively enables waste adhesive recycling and reduces environmental pollution. Specifically, the used adhesive material is collected and placed in an ultrasonic-assisted separation device. The ultrasonic frequency is set at 40-60kHz and the power is set at 300-500W. The device is then treated in a specific separation fluid for 30-60 minutes to achieve efficient waste adhesive separation and recycling.

[0054] Example 1

[0055] This embodiment provides a printing adhesive, comprising the following components in parts by weight:

[0056] 94.2 parts of core-shell microspheres; specifically, paraffin as the core and acrylate as the shell.

[0057] 1 part of oxidized nanocellulose having an aspect ratio greater than 100;

[0058] 4 parts of copper phthalocyanine;

[0059] 0.8 parts of hydrophobically modified fumed silica.

[0060] This embodiment provides a method for using a printed adhesive, comprising:

[0061] S1: Cold printing: 2400 dpi CTP platemaking technology was used to print a spiral line of adhesive (line width 0.2 mm) on the book page. The offset printing press parameters used for printing were set as follows: ink roller temperature: 25±1°C; printing pressure: 0.15-0.18 MPa; drying condition: 40°C hot air (wind speed 8 m / s); printing thickness: 2±0.3 μm.

[0062] S2: Heat-activated bonding: Using 808nm laser irradiation, the copper phthalocyanine in the adhesive can achieve selective laser heating, causing the adhesive to quickly heat up to above 65°C to achieve the bonding process.

[0063] The peel strength of the book after pasting is measured according to JIS K6854 standard ≥12N / cm 2 ; Error range ±0.5N / cm 2 Specifically, according to JIS K6854 standard, the adhesive is applied to a standard substrate (such as PET film or paper) with a printing thickness of 2±0.3 μm.

[0064] Sample size: 25mm×150mm (bonding area 25mm×25mm)

[0065] Tensile rate: 300mm / min

[0066] Ambient temperature: 23±2℃

[0067] After 808 nm laser activation (65-100° C.), a 180° peel test was performed using a universal tensile testing machine at a speed of 300 mm / min.

[0068] The average peel strength of three repeated experiments was 12.3 N / cm 2 , 12.1N / cm 2 , 12.4N / cm 2 (Error ±0.5N / cm 2 ).

[0069] The bookbinding technology used in this embodiment has passed the highest level certification of ISO 15755 (paper bonding) and is completed in Japan Toppan Printing.

[0070] In this embodiment, the rotational rheometer (shear rate 100s) was used at 25°C (cold printing temperature). -1 ) The initial viscosity of the adhesive was measured to be 1.05×10 5 mPa·s; when the temperature rises to 65°C (above the paraffin phase transition temperature), the viscosity level drops to 9.8×10 2 mPa·s, a decrease of 3 orders of magnitude. This change is due to the plasticization effect caused by the melting of paraffin wax, which significantly improves the fluidity and wettability of the adhesive. Specifically, the viscosity test method includes: using a rotational rheometer (MCR302, Anton Paar) to test the viscosity change:

[0071] Test mode: Steady shear

[0072] Shear rate: 100s-1

[0073] Temperature program: 25℃→80℃, heating rate 2℃ / min

[0074] Parallel plate specifications: diameter 25mm, gap 0.5mm

[0075] Test results:

[0076] Viscosity at 25°C: 1.05×10 5 mPa·s

[0077] Viscosity at 65°C: 9.8×10 2 mPa·s

[0078] Viscosity at 75°C: 5.6×10 2 mPa·s

[0079] The viscosity change curve shows an obvious inflection point near 65°C, confirming the plasticizing effect caused by the phase change of paraffin.

[0080] Example 2

[0081] This embodiment provides a printing adhesive, comprising the following components in parts by weight:

[0082] 94.8 parts of core-shell microspheres; specifically, paraffin as the core and acrylate as the shell.

[0083] 1.2 parts of oxidized nanocellulose with an aspect ratio greater than 100;

[0084] 3 parts copper phthalocyanine;

[0085] 1.0 part hydrophobically modified fumed silica.

[0086] This embodiment provides a method for using a printed adhesive, comprising:

[0087] S1: Cold printing: The adhesive is printed on the seal of the packaging bag using 2400dpi CTP platemaking technology. The offset printing press parameters used for printing are set as follows: ink roller temperature: 25±1°C; printing pressure: 0.15-0.18MPa; drying conditions: 40°C hot air (wind speed 8m / s); printing thickness: 2±0.3μm.

[0088] S2: Heat-activated bonding: Using 808nm laser irradiation, the copper phthalocyanine in the adhesive can achieve selective laser heating, causing the adhesive to quickly heat up to above 65°C to achieve the bonding process.

[0089] The peel strength of the packaging bag seal after pasting is measured under JIS K6854 standard ≥12N / cm 2 ; Error range ±0.5N / cm 2 .

[0090] In this embodiment, the rotational rheometer (shear rate 100s) was used at 25°C (cold printing temperature). -1 ) The initial viscosity of the adhesive was measured to be 10 5 mPa·s; when the temperature rises to 65°C (above the paraffin phase transition temperature), the viscosity level drops to 10 2 mPa·s, a decrease of three orders of magnitude. This change is due to the plasticization effect caused by the melting of paraffin wax, which significantly improves the fluidity and wettability of the adhesive.

[0091] Example 3

[0092] This embodiment provides a printing adhesive, comprising the following components in parts by weight:

[0093] 94 core-shell microspheres; specifically, paraffin as the core and acrylate as the shell.

[0094] 0.5 parts of oxidized nanocellulose with an aspect ratio greater than 100;

[0095] 5 parts of copper phthalocyanine;

[0096] 0.5 parts of hydrophobically modified fumed silica.

[0097] This embodiment provides a method for using a printed adhesive, comprising:

[0098] S1: Cold printing: The adhesive was printed on the pages using 2400 dpi CTP platemaking technology. The offset printing press parameters used for printing were set as follows: ink roller temperature: 25 ± 1°C; printing pressure: 0.15-0.18 MPa; drying conditions: 40°C hot air (wind speed 8 m / s); printing thickness: 2 ± 0.3 μm.

[0099] S2: Heat-activated bonding: Using 808nm laser irradiation, the copper phthalocyanine in the adhesive can achieve selective laser heating, causing the adhesive to quickly heat up to above 65°C to achieve the bonding process.

[0100] The peel strength of the book after pasting is measured according to JIS K6854 standard ≥12N / cm 2 ; Error range ±0.5N / cm 2 .

[0101] In this embodiment, the rotational rheometer (shear rate 100s) was used at 25°C (cold printing temperature). -1 ) The initial viscosity of the adhesive was measured to be 10 5 mPa·s; when the temperature rises to 65°C (above the paraffin phase transition temperature), the viscosity level drops to 10 2 mPa·s, a decrease of three orders of magnitude. This change is due to the plasticization effect caused by the melting of paraffin wax, which significantly improves the fluidity and wettability of the adhesive.

[0102] Example 4

[0103] In order to verify the effect of the content of oxidized nanocellulose in the adhesive on the bonding results, in this example, the mass fractions of oxidized nanocellulose were designed to be 0.1%, 0.3%, 0.5%, 1.0%, 1.5%, and 2.0%, respectively. Correspondingly, the mass fractions of core-shell structured microspheres were 95.1%, 94.9%, 94.7%, 94.2%, 93.7%, and 93.2%; the mass fraction of copper phthalocyanine was 4%; and the mass fraction of hydrophobically modified fumed silica was 0.8%.

[0104] The specific usage and testing methods are the same as those in Example 1 and will not be described in detail here.

[0105] After the adhesives with different oxidized nanocellulose contents were pasted, their printing uniformity was observed, and the peel strength and storage modulus were tested. The specific test results are shown in Table 1. The peel strength was based on the JIS K6854 standard, 180° peeling, and a tensile rate of 300 mm / min.

[0106] Table 1 Test results of adhesives with different oxidized nanocellulose contents

[0107]

[0108] This example demonstrates that when the oxidized nanocellulose content is 0.5-1.2 wt%, the nanocellulose can form a stable three-dimensional network, achieving both printing precision and strength. When the oxidized nanocellulose content is too low, the adhesive layer after printing and pasting is insufficiently strong, resulting in breakpoints during printing. When the oxidized nanocellulose content is too high, printing fluidity deteriorates, uniformity after heat-activated pasting is poor, and the strength of the adhesive layer is insufficient.

[0109] Example 5

[0110] In order to verify the effect of the content of the photothermal conversion agent in the adhesive on the pasting result, the mass fractions of copper phthalocyanine were designed to be 1%, 3%, 4%, 5%, 6%, and 7% respectively in this embodiment. Correspondingly, the mass fractions of the core-shell structured microspheres were 97.2%, 95.2%, 94.2%, 93.2%, 92.2%, and 91.2%; the mass fraction of oxidized nanocellulose was 1%; and the mass fraction of hydrophobically modified fumed silica was 0.8%.

[0111] The specific usage and testing methods are the same as those in Example 1 and will not be described in detail here.

[0112] The corresponding laser heating rate, local temperature and bonding activation time of the adhesives with different photothermal conversion agent contents were tested during thermal activation bonding. The specific test results are shown in Table 2.

[0113] Table 2 Test results of adhesives with different copper phthalocyanine contents

[0114] Copper phthalocyanine (%) Laser heating rate (℃ / s) Local temperature (℃) Bonding activation time (s) 1 50 58 >5 3 180 72 2 4 210 83 1 5 210 85 1 6 220 95 1(but the adhesive layer is carbonized) 7 230 100 1(but the adhesive layer is carbonized)

[0115] This example demonstrates that when the copper phthalocyanine content is 3-5wt%, a heating rate of >200°C / s allows for rapid activation while avoiding overheating damage. When the copper phthalocyanine content is too low, the heating rate is slow, prolonging the bonding activation time. When the copper phthalocyanine content is too high, localized carbonization occurs after laser irradiation, leading to a sharp decrease in bond strength.

[0116] Example 6

[0117] In order to verify the effect of the content of rheology modifier in the adhesive on the pasting result, in this embodiment, the mass fractions of hydrophobically modified fumed silica are designed to be 0.2%, 0.5%, 0.8%, 1.0%, and 1.5%, respectively. Correspondingly, the mass fractions of core-shell structured microspheres are 94.8%, 94.5%, 94.2%, 94.0%, and 93.5%; the mass fraction of oxidized nanocellulose is 1%; and the mass fraction of copper phthalocyanine is 4%.

[0118] The specific usage and testing methods are the same as those in Example 1 and will not be described in detail here.

[0119] For the adhesives with different photothermal conversion agent contents, their thixotropic index, fluidity during cold printing (cold printing fluidity), and spreadability during heat-activated pasting (hot adhesive spreadability) were tested. The specific test results are shown in Table 3.

[0120] Table 3 Test results of adhesives with different hydrophobically modified fumed silica contents

[0121]

[0122] This example demonstrates that when the hydrophobically modified fumed silica content is 0.5-1.0 wt%, the thixotropic index is 4.8-5.2, which balances printing and bonding requirements. Excessively high or low hydrophobically modified fumed silica content can affect cold printing fluidity and hot adhesive spreadability.

[0123] Example 7 - Ultrasonic assisted separation experiment

[0124] A used adhesive sample (area 10 cm×10 cm, adhesive layer thickness 2 μm) was placed in an ultrasonic separation device, and an ethanol-water mixed solution (volume ratio 1:1) was added as a separation liquid.

[0125] The ultrasonic frequency was set to 50kHz and the power to 400W. After 45 minutes of treatment, the separated adhesive components were collected using a filter membrane. The separation efficiency was calculated by the gravimetric method:

[0126] Separation efficiency = (1 - residual adhesive mass / initial adhesive mass) × 100% Separation efficiency = (1 - initial adhesive mass / residual adhesive mass) × 100%.

[0127] In this embodiment, the average value was obtained through three repeated experiments. The results of the three repeated experiments showed that when a mixed solution of ethanol and water with a volume ratio of 1:1 was used as the separation liquid, the average separation efficiency of the adhesive was 98.0%±0.2%, which effectively realized the recycling and reuse of waste glue and reduced environmental pollution.

[0128] This application creatively proposes an adhesive system in which core-shell structured microspheres and nanocellulose reinforcement phases cooperate with each other. The core-shell structured microspheres have an acrylate shell and paraffin as a core. This structural design gives the adhesive special performance changes at different temperatures, enabling the unique operation of cold printing and heat-activated bonding, so that the coating and bonding of the adhesive are carried out independently in two steps. At the same time, the nanocellulose reinforcement phase can form a three-dimensional network structure in the adhesive, enhance the cohesion and overall performance of the adhesive, and improve the mechanical strength and stability of the adhesive during the cold printing process; the rheology regulator can effectively adjust the rheological properties of the adhesive, so that it has good fluidity and thixotropy during the printing process, ensuring the uniformity and stability of the printed layer; the photothermal converter can achieve rapid heating, accurately control the activation process of the adhesive, and improve the bonding efficiency; this application can achieve the effect of printing at low temperature and bonding at high temperature through the combination of the above components, which can ensure both the bonding accuracy of the adhesive and the bonding strength of the adhesive, solving the problem that the accuracy and strength of traditional adhesives cannot be achieved at the same time.

[0129] It is understandable that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A printed adhesive, characterized in that: The invention comprises the following components: core-shell structured microspheres, a nanocellulose reinforcing phase, a photothermal conversion agent and a rheology regulator; the core of the core-shell structured microspheres is paraffin, and the shell of the core-shell structured microspheres is acrylate; the mass fraction of the nanocellulose reinforcing phase is 0.5-1.2 wt%; the mass fraction of the photothermal conversion agent is 3-5 wt%; and the mass fraction of the rheology regulator is 0.5-1.0 wt%.

2. The printing adhesive according to claim 1, characterized in that: The particle size distribution D50 of the core-shell structured microspheres is 1.8 microns.

3. The printing adhesive according to claim 1, characterized in that: The nanocellulose reinforcement phase is oxidized nanocellulose with an aspect ratio greater than 100.

4. The printing adhesive according to claim 1, characterized in that: The light-to-heat conversion agent is copper phthalocyanine.

5. The printing adhesive according to claim 1, characterized in that: The rheology modifier is hydrophobically modified fumed silica.

6. The printing adhesive according to claim 1, characterized in that: The mass fraction of the nanocellulose reinforcement phase is 0.8-1.0wt%; The mass fraction of the photothermal conversion agent is 3.5-4.5wt%; The mass fraction of the rheology modifier is 0.6-0.8 wt%.

7. The method for using the printing adhesive according to any one of claims 1 to 6, characterized in that: include: Cold printing: Printing and applying the adhesive to the location to be pasted at a first temperature, which is lower than the phase transition temperature of paraffin wax and is 25-40°C. Thermally activated bonding: At the second temperature, the core of the core-shell structure microspheres is melted to achieve dynamic bonding; the peel strength of the adhesive after thermal activation is ≥12N / cm 2 , error ±0.5N / cm 2 ; The second temperature is higher than the phase transition temperature of paraffin, which is 65-100°C.

8. The method for using the printing adhesive according to claim 7, characterized in that: In the heat activated bonding stage, the temperature is raised to a second temperature by laser heating.

9. Use of a printing adhesive according to any one of claims 1 to 6, characterized in that: The adhesive is used in the field of bookbinding.

10. Use of a printing adhesive according to any one of claims 1 to 6, characterized in that: The adhesive is used in the field of intelligent packaging.

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