Bio-based imd inks and methods of making the same, injection molded articles and methods of processing the same

Abstract

The application provides a kind of bio-based IMD ink and its preparation method, injection molding product and its processing method.The bio-based IMD ink includes the following components by mass fraction: ink: bio-based modified saturated polyester 50-60 parts;Dispersant 5-10 parts;Pigment 10-15 parts;Auxiliary 1-2 parts;Filler 5-8 parts;Solvent 20-30 parts;Adhesion agent 1-3 parts;Curing agent: bio-based modified PDI type curing agent 10-15 parts;Curing agent is added to ink mixture and coated on substrate film to form IMD ink layer.The bio-based IMD ink can ensure better adhesion strength and elongation performance, and has low VOC emission and environmental protection.

Description

Bio-based IMD inks and their preparation methods, injection molded products and their processing methods Technical Field

[0001] This invention relates to the field of ink technology, and in particular to a bio-based IMD ink and its preparation method, injection molded products and their processing methods. Background Technology

[0002] In-mold decoration (IMD) technology, as an efficient and environmentally friendly surface decoration process, is widely used in consumer electronics (such as mobile phones and tablets), automotive central control screens, and smart home appliances. Its core advantage lies in embedding the printed pattern layer inside the injection molded part to achieve a wear-resistant and color-long-lasting design effect. For example, invention patent applications CN201210183983.8 and CN202410049158.1 both use IMD inks for in-mold injection molding. IMD inks contain polyester resins, and the cured inks have good adhesion strength and elongation properties. However, China's GB33372-2025 classifies IMD inks separately for the first time, with requirements 20% stricter than ordinary inks. Conventional polyester resins have relatively high volatile organic compound emissions. Therefore, there is an urgent need to develop an environmentally friendly IMD ink with low VOC emissions. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an environmentally friendly bio-based IMD ink, its preparation method, injection molded products and processing method that can ensure good adhesion strength and elongation performance and low VOC emissions.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A bio-based IMD ink comprises the following components in parts by weight:

[0006] Ink:

[0007]

[0008]

[0009] Hardener:

[0010] 10 to 15 parts of bio-based modified PDI type curing agent;

[0011] The curing agent is added to the ink and mixed, and then coated onto the substrate film to form an IMD ink layer.

[0012] In one embodiment, the bio-based modified saturated polyester is Guangzhou Qingtian Bio-based Modified Saturated Polyester YM136 and / or Guangzhou Qingtian Bio-based Modified Saturated Polyester YM138.

[0013] In one embodiment, the dispersant is Lubrizol 29000.

[0014] In one embodiment, the pigment is Orion NX505 carbon black.

[0015] In one embodiment, the additives include acrylate leveling agents and defoamers.

[0016] In one embodiment, the filler is talc.

[0017] In one embodiment, the solvent is propylene glycol diacetate and divalent ester.

[0018] In one embodiment, the adhesive is at least one selected from vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, and 3-mercaptotrimethoxysilane.

[0019] In one embodiment, the bio-based modified PDI curing agent is Mitsui Chemicals D-3725N.

[0020] In one embodiment, the molecular weight of the bio-based modified saturated polyester is 6,000 to 20,000.

[0021] In one embodiment, the bio-based molecular weight percentage of the bio-based modified saturated polyester is 40% to 50%.

[0022] In one embodiment, the bio-based molecular weight of the bio-based modified PDI curing agent is 60% to 75%.

[0023] In one embodiment, the NCO- molecular weight percentage of the bio-based modified PDI curing agent is 12% to 16%.

[0024] In one embodiment, the substrate film is a PC film or a PET film.

[0025] A method for preparing a bio-based IMD ink, used to prepare the bio-based IMD ink described in any of the above embodiments, the method comprising the following steps:

[0026] Obtain the components of the ink and the curing agent;

[0027] The components of the ink are mixed to obtain the ink.

[0028] The curing agent is added to the ink for mixing to obtain the bio-based IMD ink.

[0029] In one embodiment, the components of the ink are mixed, specifically as follows:

[0030] Bio-based modified saturated polyester, dispersant, pigment, additives, filler and adhesive are added to the solvent one by one in sequence and stirred and mixed, then ground and filtered.

[0031] In one embodiment, under the condition of a stirring speed of 200 r / min to 400 r / min, the bio-based modified saturated polyester, dispersant, pigment, additive, filler and adhesive are added to the solvent one by one and stirred until all are added. Then, the mixture is stirred and dispersed under the condition of a stirring speed of 600 r / min to 1000 r / min.

[0032] In one embodiment, the particles in the ink are ground to a diameter of less than or equal to 7 μm.

[0033] A method for processing injection molded products includes the following steps:

[0034] Obtain the bio-based IMD ink prepared by the preparation method of the bio-based IMD ink described in any of the above embodiments;

[0035] The bio-based IMD ink is used to print on a substrate film to form an IMD ink layer on the substrate film;

[0036] The IMD ink layer is subjected to a heat insulation operation to form a hexagonal boron nitride nanosheet layer on the side of the IMD ink layer away from the substrate film, thereby obtaining an IMD film;

[0037] The IMD film is placed in an in-mold injection molding operation to obtain an injection molded product.

[0038] In one embodiment, before the step of performing a heat insulation operation on the IMD ink layer and after the step of printing the substrate film with the bio-based IMD ink, the method for processing the injection molded article further includes the following steps:

[0039] The IMD ink layer is then cured and dried.

[0040] An injection-molded article is obtained by the injection-molded article processing method described in any of the above embodiments.

[0041] Compared with the prior art, the present invention has at least the following advantages:

[0042] The bio-based IMD ink of this invention incorporates bio-based modified saturated polyester. Due to the branched structure of the bio-based modified saturated polyester, the curing temperature of the bio-based IMD ink is lowered, reducing the thermal deformation of the substrate film. Furthermore, the bio-based modified saturated polyester contains a large number of hydroxyl and carboxyl groups, effectively improving adhesion and ductility on the substrate film. The use of bio-based modified saturated polyester makes the bio-based IMD ink more suitable for complex curved substrates and provides microcrack repair capabilities, thus significantly improving the mechanical properties of injection molded products. Moreover, the low VOC emissions of the bio-based modified saturated polyester and the bio-based modified PDI-type curing agent ensure the environmental friendliness of the bio-based IMD ink. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 is a flowchart of a method for preparing bio-based IMD ink according to an embodiment of the present invention;

[0045] Figure 2 is a flowchart of a processing method for injection-molded articles according to an embodiment of the present invention;

[0046] Figures 3 to 6 are actual images of the injection molded products prepared using each component of formula 5 in Example 1. Detailed Implementation

[0047] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0048] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0050] This application provides a bio-based IMD ink. The bio-based IMD ink comprises the following components in parts by weight: ink: 50-60 parts of bio-based modified saturated polyester; 5-10 parts of dispersant; 10-15 parts of pigment; 1-2 parts of additives; 5-8 parts of filler; 20-30 parts of solvent; 1-3 parts of adhesion promoter; curing agent: 10-15 parts of bio-based modified PDI type curing agent; the curing agent is added to the ink mixture and coated onto a substrate film to form an IMD ink layer.

[0051] The aforementioned bio-based IMD ink incorporates bio-based modified saturated polyester. Due to the branched structure of the bio-based modified saturated polyester, the curing temperature of the bio-based IMD ink is lowered, reducing thermal deformation of the substrate film. Furthermore, the bio-based modified saturated polyester contains a large number of hydroxyl and carboxyl groups, effectively improving adhesion and ductility on the substrate film. The use of bio-based modified saturated polyester makes the bio-based IMD ink more suitable for complex curved substrates and provides micro-crack repair capabilities, thus significantly improving the mechanical properties of injection molded products. Moreover, the low VOC emissions of both the bio-based modified saturated polyester and the bio-based modified PDI-type curing agent ensure the environmental friendliness of the bio-based IMD ink.

[0052] To better understand the bio-based IMD ink of this application, the following further explanation is provided:

[0053] One embodiment of the bio-based IMD ink comprises the following components in parts by weight: ink: 50 to 60 parts of bio-based modified saturated polyester; 5 to 10 parts of dispersant; 10 to 15 parts of pigment; 1 to 2 parts of additives; 5 to 8 parts of filler; 20 to 30 parts of solvent; 1 to 3 parts of adhesion agent; curing agent: 10 to 15 parts of bio-based modified PDI type curing agent; the curing agent is added to the ink mixture and coated onto the substrate film to form an IMD ink layer.

[0054] The aforementioned bio-based IMD ink incorporates bio-based modified saturated polyester. Due to the branched structure of the bio-based modified saturated polyester, the curing temperature of the bio-based IMD ink is lowered, reducing thermal deformation of the substrate film. Furthermore, the bio-based modified saturated polyester contains a large number of hydroxyl and carboxyl groups, effectively improving adhesion and ductility on the substrate film. The use of bio-based modified saturated polyester makes the bio-based IMD ink more suitable for complex curved substrates and provides micro-crack repair capabilities, thus significantly improving the mechanical properties of injection molded products. Moreover, the low VOC emissions of both the bio-based modified saturated polyester and the bio-based modified PDI-type curing agent ensure the environmental friendliness of the bio-based IMD ink.

[0055] In one embodiment, the bio-based modified saturated polyester is Guangzhou Qingtian Bio-based Modified Saturated Polyester YM136 and / or Guangzhou Qingtian Bio-based Modified Saturated Polyester YM138.

[0056] In one embodiment, the dispersant is Lubrizol 29000.

[0057] In one embodiment, the pigment is Orion NX505 carbon black.

[0058] In one embodiment, the additives include an acrylate leveling agent and a defoamer. Further, the defoamer is BASF PB 2770.

[0059] In one embodiment, the filler is talc.

[0060] In one embodiment, the solvent is propylene glycol diacetate and divalent ester.

[0061] In one embodiment, the adhesive is at least one selected from vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, and 3-mercaptotrimethoxysilane.

[0062] In one embodiment, the bio-based modified PDI curing agent is Mitsui Chemicals D-3725N.

[0063] In one embodiment, the molecular weight of the bio-based modified saturated polyester is 6,000 to 20,000, which better ensures the adhesion and stretchability of the bio-based IMD ink on the substrate film.

[0064] In one embodiment, the bio-based molecular weight of the bio-based modified saturated polyester is 40% to 50%, which better ensures the adhesion and stretchability of the bio-based IMD ink on the substrate film.

[0065] In one embodiment, the bio-based modified PDI curing agent has a bio-based molecular weight ratio of 60% to 75%, which better reduces VOC emissions and improves the environmental friendliness of bio-based IMD inks.

[0066] In one embodiment, the NCO- molecular weight percentage of the bio-based modified PDI curing agent is 12% to 16%.

[0067] In one embodiment, the substrate film is a PC film or a PET film.

[0068] This application also provides a method for preparing a bio-based IMD ink, used to prepare the bio-based IMD ink of any of the above embodiments. The method for preparing the bio-based IMD ink includes the following steps: obtaining the components of the ink and a curing agent; mixing the components of the ink to obtain the ink; adding the curing agent to the ink and mixing to obtain the bio-based IMD ink.

[0069] The above-described method for preparing bio-based IMD inks, which involves preparing the ink and curing agent on-site, effectively ensures the curing stability and uniformity of the bio-based IMD ink layer.

[0070] To better understand the preparation method of the bio-based IMD ink of this application, the following further explanation is provided:

[0071] One embodiment of the preparation method of bio-based IMD ink includes the following steps:

[0072] S100. Obtain the components of the ink and the curing agent. Further, in this embodiment, the ink comprises the following components in parts by weight: Ink: 50-60 parts of bio-based modified saturated polyester; 5-10 parts of dispersant; 10-15 parts of pigment; 1-2 parts of additives; 5-8 parts of filler; 20-30 parts of solvent; 1-3 parts of adhesion promoter; The curing agent comprises the following components in parts by weight: 10-15 parts of bio-based modified PDI type curing agent. Further, when bio-based IMD ink is required, the curing agent is added to the ink mixture, and after uniform mixing, it is quickly coated onto the substrate film to form an IMD ink layer; that is, the ink and curing agent are prepared and used immediately.

[0073] S200: The components of the ink are mixed to obtain the ink.

[0074] S300: Add the curing agent to the ink and mix to obtain bio-based IMD ink.

[0075] The above-described method for preparing bio-based IMD inks, which involves preparing the ink and curing agent on-site, effectively ensures the curing stability and uniformity of the bio-based IMD ink layer.

[0076] In one embodiment, the ink components are mixed as follows: bio-based modified saturated polyester, dispersant, pigment, additives, filler, and adhesion promoter are added sequentially to a solvent and stirred. The mixture is then ground and filtered. This sequential addition and mixing of ink components effectively breaks down the molecular chain entanglement of the bio-based modified polyester and reduces gelation caused by high local concentrations. This significantly improves the uniform dispersion and viscosity stability of the ink components. Subsequently, a curing agent is added to the ink and mixed, allowing for immediate use and effectively ensuring the curing stability and uniformity of the IMD ink layer.

[0077] In one embodiment, under the condition of stirring speed of 200 r / min to 400 r / min, bio-based modified saturated polyester, dispersant, pigment, additives, filler and adhesion promoter are added to the solvent one by one and stirred until all are added. Then, the mixture is stirred and dispersed under the condition of stirring speed of 600 r / min to 1000 r / min for 10 min to 15 min, which better ensures the uniform dispersion and viscosity stability of each component in the ink.

[0078] In one embodiment, the curing agent is added to the ink for mixing. Specifically, the curing agent is added to the ink and stirred at a speed of 600 rpm to 1000 rpm for 10 to 20 minutes. This process effectively ensures the uniform dispersion of the curing agent in the ink, thereby ensuring the curing stability and uniformity of the IMD ink layer.

[0079] It should be noted that when bio-based modified polyester is used in bio-based IMD inks, the resulting IMD ink layer has poor high-temperature instantaneous resistance. That is, bio-based modified polyester is prone to molecular chain breakage at high temperatures, which in turn causes the IMD ink layer to crack easily under the instantaneous high temperature of injection molding. Therefore, in order to improve the high-temperature resistance of bio-based IMD inks, in one embodiment, the ink also includes the following component: hexagonal boron nitride nanosheets. Hexagonal boron nitride nanosheets have good high-temperature instantaneous resistance and, when dispersed in bio-based IMD inks, effectively improve the thermal conductivity of the IMD ink layer, thereby improving the high-temperature instantaneous resistance of bio-based IMD inks.

[0080] It should be noted that while adding hexagonal boron nitride nanosheets to bio-based IMD inks effectively improves their high-temperature transient resistance, the instantaneous high temperatures during injection molding, which can reach 320°C, still have limitations in improving the high-temperature transient resistance of bio-based IMD inks. This is due to the dispersion of the hexagonal boron nitride nanosheets within the IMD and the proportion of the main components in the bio-based IMD ink, which is crucial for ensuring the ink's extensibility and adhesion. Therefore, the effect of the added hexagonal boron nitride nanosheets on improving the high-temperature transient resistance of bio-based IMD inks is limited. To further improve the high-temperature transient resistance of bio-based IMD inks while ensuring their adhesion, in one embodiment, the hexagonal boron nitride nanosheets are arranged in the thickness direction of the IMD ink layer... The reduced boron nitride nanosheet content gradient means that the content of hexagonal boron nitride nanosheets on the side of the IMD ink layer closest to the substrate film is less than that on the side of the IMD ink layer furthest from the substrate film. This ensures a lower content of hexagonal boron nitride nanosheets on the side closest to the substrate film, thus guaranteeing the adhesion of the bio-based IMD ink to the substrate film. Furthermore, the reduced hexagonal boron nitride nanosheet content gradient along the thickness direction of the IMD ink layer further improves the thermal conductivity and high-temperature transient resistance of the bio-based IMD ink. In particular, the reduced hexagonal boron nitride nanosheet content gradient along the thickness direction of the bio-based IMD ink layer mitigates cracking or peeling caused by large internal stress differences due to internal expansion.

[0081] In one embodiment, the components of the ink are mixed, specifically as follows:

[0082] Bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets and adhesion promoter were added to the solvent one by one and stirred and mixed. Then, the mixture was ground and filtered to obtain ink A.

[0083] Bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets and adhesion promoter were added to the solvent one by one and stirred and mixed. Then, the mixture was ground and filtered to obtain ink B.

[0084] Bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets and adhesion agent were added to the solvent one by one and stirred and mixed. Then, the mixture was ground and filtered to obtain C ink.

[0085] It is understood that the following components in ink A are present in the following mass percentages: 50-60 parts bio-based modified saturated polyester; 5-10 parts dispersant; 10-15 parts pigment; 1-2 parts additives; 5-8 parts filler; 20-30 parts solvent; 1-3 parts adhesion agent; and the hexagonal boron nitride nanosheets in ink A account for 2%-5% of the total mass, and the added bio-based modified PDI type curing agent accounts for 10-15 parts of the total mass. Ink B is present in the following mass percentages: 50-60 parts bio-based modified saturated polyester; 5-10 parts dispersant; 10-15 parts pigment; 1-2 parts additives; 5-8 parts filler; solvent... 20-30 parts; 1-3 parts of adhesive, and the mass percentage of hexagonal boron nitride nanosheets in ink B is 10%-18%, and the mass percentage of added bio-based modified PDI type curing agent is 10-15 parts; the mass percentage of the following components in ink C is as follows: 50-60 parts of bio-based modified saturated polyester; 5-10 parts of dispersant; 10-15 parts of pigment; 1-2 parts of additives; 5-8 parts of filler; 20-30 parts of solvent; 1-3 parts of adhesive, and the mass percentage of hexagonal boron nitride nanosheets in ink C is 28%-35%, and the mass percentage of added bio-based modified PDI type curing agent is 10-15 parts.

[0086] In one embodiment, a curing agent is added to the ink for mixing. Specifically, the curing agent is added to inks A, B, and C respectively and stirred to obtain ink A, ink B, and ink C. Further, the stirring speed is 600 r / min to 1000 r / min, and the stirring time is 10 min to 20 min. Further, the ink is ground until the particle size is less than or equal to 7 μm.

[0087] This application also provides a method for processing injection-molded articles. The above-described method for processing injection-molded articles includes the following steps: obtaining bio-based IMD ink prepared by the preparation method of bio-based IMD ink of any of the above embodiments; performing a printing operation on a substrate film using the bio-based IMD ink to form an IMD ink layer on the substrate film; performing a heat insulation operation on the IMD ink layer to form a hexagonal boron nitride nanosheet layer on the side of the IMD ink layer away from the substrate film, thereby obtaining an IMD film; and performing an in-mold injection molding operation on the IMD film to obtain an injection-molded article.

[0088] The above-described injection molding process forms a heat-insulating layer on the side of the IMD ink layer away from the substrate film, specifically a hexagonal boron nitride nanosheet layer. This hexagonal boron nitride nanosheet layer provides superior heat insulation. Furthermore, based on the gradient variation in the content of hexagonal boron nitride nanosheets along the thickness direction in the IMD ink layer, the difference in thermal expansion between the bio-based IMD ink and the hexagonal boron nitride nanosheet layer is reduced. This mitigates the peeling of the bio-based IMD ink and the hexagonal boron nitride nanosheet layer during injection molding and significantly improves the high-temperature resistance of the IMD ink layer during injection molding, thereby effectively increasing the processing yield of the injection molded product.

[0089] To better understand the processing method of the injection-molded articles of this application, the processing method of the injection-molded articles of this application is further explained below:

[0090] One embodiment of the injection molding article processing method includes the following steps:

[0091] S001. Obtain the bio-based IMD ink prepared by the preparation method of any of the above embodiments.

[0092] S003. A bio-based IMD ink is used to print on the substrate film to form an IMD ink layer on the substrate film.

[0093] S005. A heat-insulating operation is performed on the IMD ink layer to form a hexagonal boron nitride nanosheet layer on the side of the IMD ink layer away from the substrate film, thus obtaining an IMD film. It is understood that increasing the amount of hexagonal boron nitride nanosheets in bio-based IMD inks can significantly improve their high-temperature resistance. However, the instantaneous temperature during injection molding can reach as high as 320°C. The bio-based modified polyester in the bio-based IMD ink is difficult to completely avoid the influence of instantaneous temperature during injection molding; that is, the molecular chains in the bio-based modified polyester in the bio-based IMD ink can still break, causing micro-cracks in the IMD ink layer. Therefore, in this application, a heat-insulating layer is formed on the side of the IMD ink layer away from the substrate film. This involves forming a hexagonal boron nitride nanosheet layer on the side of the IMD ink layer away from the substrate film. The hexagonal boron nitride nanosheet layer has a better thermal insulation effect, and based on the gradient change of the content of hexagonal boron nitride nanosheets along the thickness direction in the IMD ink layer, the difference in thermal expansion between the bio-based IMD ink and the hexagonal boron nitride nanosheet layer is reduced, thereby alleviating the peeling of the bio-based IMD ink and the hexagonal boron nitride nanosheet layer during injection molding, and greatly improving the high temperature resistance of the IMD ink layer during injection molding, thus effectively improving the processing yield of injection molded products.

[0094] S007. The IMD film is placed in the mold for in-mold injection molding to obtain the injection molded product. It is understood that placing the IMD film in the molding cavity for in-mold injection molding is a conventional technique, therefore, it will not be described in detail here.

[0095] The above-described injection molding process forms a heat-insulating layer on the side of the IMD ink layer away from the substrate film, specifically a hexagonal boron nitride nanosheet layer. This hexagonal boron nitride nanosheet layer provides superior heat insulation. Furthermore, based on the gradient variation in the content of hexagonal boron nitride nanosheets along the thickness direction in the IMD ink layer, the difference in thermal expansion between the bio-based IMD ink and the hexagonal boron nitride nanosheet layer is reduced. This mitigates the peeling of the bio-based IMD ink and the hexagonal boron nitride nanosheet layer during injection molding and significantly improves the high-temperature resistance of the IMD ink layer during injection molding, thereby effectively increasing the processing yield of the injection molded product.

[0096] In one embodiment, prior to the step of printing the substrate film with bio-based IMD ink, the injection molding process further includes the following step: cleaning and activating the substrate film. Specifically, the cleaning and activation treatment of the substrate film involves ultrasonically cleaning the substrate film with acetone for 5-8 minutes, followed by rinsing with deionized water, drying with nitrogen, and finally treating with oxygen plasma for 1-2 minutes at a power of 50W. This process improves the adhesion strength of the bio-based IMD ink to the substrate film.

[0097] In one embodiment, before the step of heat insulation of the IMD ink layer and after the step of printing the substrate film with bio-based IMD ink, the method for processing the injection molded article further includes the following step: curing and drying the IMD ink layer. Further, the curing and drying operation is performed on the IMD ink layer to cure it to 60%–70% of its curing degree. Specifically, this is done by heat curing at a temperature of 80°C–85°C for 20–40 minutes. It is understandable that thermal curing at 80℃~85℃ for 25min~45min achieves a curing degree of 60%~70% for the bio-based IMD ink. Then, printing a hexagonal boron nitride nanosheet layer onto the IMD ink layer causes the contact surface between the IMD ink layer and the hexagonal boron nitride nanosheet layer to melt, forming a fused layer structure with a transitional content of hexagonal boron nitride nanosheets between them. This improves the adhesion strength of the hexagonal boron nitride nanosheet layer to the IMD ink layer and reduces the difference in thermal expansion between the hexagonal boron nitride nanosheet layer and the IMD ink layer during injection molding. This reduces the peeling of the IMD ink layer and the hexagonal boron nitride nanosheet layer during injection molding and greatly ensures the high-temperature resistance of the IMD ink layer during injection molding, thereby effectively improving the processing yield of injection molded products.

[0098] In one embodiment, the thickness of the IMD ink layer is 20 μm to 50 μm. Furthermore, the thickness of the hexagonal boron nitride nanosheet layer is 2 μm to 3 μm, which effectively ensures the heat insulation effect.

[0099] In one embodiment, a bio-based IMD ink is used to print on the substrate film, and the specific operation is as follows:

[0100] Ink A is spin-coated onto the substrate film using a spin coater, followed by preheating and drying, and UV curing to 60%–70% cure rate, forming an ink A layer on the substrate film. Further, ink A is applied to the substrate film, and the spin coater is operated at 2000 rpm for 30 seconds to allow ink A to spread and form. Then, it is dried at 65°C for 90 seconds under 0.5 MPa nitrogen purging conditions, followed by a 300 mJ / cm² curing process. 2 UV cured to 60%–70% curing degree.

[0101] Further, ink B is spin-coated onto ink layer A using a spin coater, followed by preheating and drying, and UV curing to 60%–70% cure rate, forming ink layer B on ink layer A. Next, ink B is added onto ink layer A, and the spin coater speed is controlled at 1800 rpm for 35 seconds to allow ink B to spread and form. Then, under a vacuum of -0.6 bar, it is heated to 70°C and dried for 75 seconds, followed by UV curing at 350 mJ / cm² to 60%–70% cure rate.

[0102] Further, ink C is spin-coated onto ink layer B using a spin coater, followed by preheating and drying, and UV curing to 60%–70% cure rate, forming ink layer C on ink layer B. Next, ink C is added onto ink layer B, and the spin coater speed is controlled at 2000 rpm for 20 seconds to allow ink B to spread and form. Then, it is dried under -0.6 bar vacuum and hot air convection at 60°C for 60 seconds using infrared heating, followed by UV curing at 400 mJ / cm² to 60%–70% cure rate.

[0103] It is understandable that curing ink layer A to 60%–70% curing level and then spin-coating ink B onto ink layer A creates a molten layer structure with a transitional content of hexagonal boron nitride nanosheets between ink layers A and B. This not only improves the adhesion strength of ink layer B to ink layer A but also reduces the difference in thermal expansion between ink layers A and B during injection molding, thereby reducing the local stress difference between ink layers A and B during injection molding. This mitigates cracking or peeling of the IMD ink layer and effectively improves the processing yield of injection molded products. Furthermore, curing ink layer B to 60%–70% curing level and then spin-coating ink C onto ink layer B creates a hexagonal boron nitride layer between ink layers B and C. The transitional molten layer structure with a high nanosheet content not only improves the adhesion strength of ink layer C to ink layer B, but also reduces the difference in thermal expansion between ink layers B and C during injection molding. This reduces the local stress difference between ink layers B and C during injection molding, thereby mitigating cracking or peeling of the IMD ink layer and effectively improving the processing yield of injection molded products. Furthermore, by curing ink layer C to only 60%–70% of its curing degree, and then printing hexagonal boron nitride nanosheets on the IMD ink layer, peeling between the IMD ink layer and the hexagonal boron nitride nanosheets during injection molding is similarly mitigated, and the high-temperature resistance of the IMD ink layer during injection molding is greatly ensured, thus effectively improving the processing yield of injection molded products.

[0104] In one embodiment, the IMD ink layer undergoes a heat insulation process, specifically as follows: a hexagonal boron nitride nanosheet suspension is spin-coated onto ink layer C using a spin coater, followed by preheating and drying, and then complete UV curing to form a hexagonal boron nitride nanosheet layer on ink layer C. Further, the hexagonal boron nitride nanosheet suspension comprises the following components in parts by weight: 5-8 parts hexagonal boron nitride nanosheets; 0.5-1 part KH-560 silane coupling agent; 85-90 parts propylene glycol methyl ether acetate; 0.3-0.5 parts BYK-358N leveling agent; and 1-2 parts PET4A crosslinking agent. Further, the hexagonal boron nitride nanosheet suspension is prepared by uniformly mixing hexagonal boron nitride nanosheets, KH-560 silane coupling agent, propylene glycol methyl ether acetate, BYK-358N leveling agent, and PET4A crosslinking agent. Furthermore, the stirring speed is 600 r / min to 800 r / min, and the stirring time is 10 min to 20 min. Further, at a temperature of 23℃ to 25℃, the hexagonal boron nitride nanosheet suspension is added to the ink C layer. The spin coater is first controlled at a speed of 800 rpm for 10 s to spread the hexagonal boron nitride nanosheet suspension. Then, under a magnetic field of 0.5T to 0.6T, the speed is controlled at 2500 rpm for 40 s to form the hexagonal boron nitride nanosheet suspension. Then, it is dried at 35℃ for 20 min in an 8MPa CO2 gas environment. Next, under a nitrogen atmosphere, UV curing is first performed at a 405nm LED at 100 mJ / cm², then UV curing is performed at a 385nm LED at 500 mJ / cm². Finally, it is heat-cured at 150℃ for 5 min.

[0105] It is understandable that the spin coater is first controlled at a speed of 800 rpm for 10 seconds to allow the hexagonal boron nitride nanosheet suspension to spread, ensuring a uniform coverage of the hexagonal boron nitride nanosheet suspension on the ink C layer and improving the edge shrinkage of the hexagonal boron nitride nanosheet layer. Then, under a magnetic field of 0.5T to 0.6T, the speed is controlled at 2500 rpm for 40 seconds to allow the hexagonal boron nitride nanosheet suspension to form, that is, the magnetic field induces the horizontal alignment of the hexagonal boron nitride nanosheets, which better ensures the formation of a hexagonal boron nitride nanosheet layer with good thermal insulation effect.

[0106] This application also provides an injection-molded article, obtained by the processing method of the injection-molded article of any of the above embodiments. Further, the injection-molded article includes an injection-molded portion and an IMD coating. The IMD coating is embedded within the injection-molded portion. Along the thickness direction of the IMD ink layer, the content of hexagonal boron nitride nanosheets decreases gradually, and the content of hexagonal boron nitride nanosheets on the side of the IMD ink layer away from the injection-molded portion is less than the content of hexagonal boron nitride nanosheets on the side of the IMD ink layer closer to the injection-molded body. Further, a heat-insulating layer is provided on the side of the IMD ink layer closer to the injection-molded portion, and the IMD ink layer contacts the injection-molded body through the heat-insulating layer. Further, the heat-insulating layer is a hexagonal boron nitride nanosheet layer. Further, the total thickness of the IMD ink layer and the heat-insulating layer is 20 μm to 50 μm. Further, the thickness of the heat-insulating layer is 2 μm to 3 μm.

[0107] It is understandable that the formation of hexagonal boron nitride nanosheets on the IMD ink layer improves the high-temperature resistance of the IMD ink layer during injection molding, thereby effectively improving the processing yield of injection molded products.

[0108] Compared with the prior art, the present invention has at least the following advantages:

[0109] The bio-based IMD ink of this invention incorporates bio-based modified saturated polyester. Due to the branched structure of the bio-based modified saturated polyester, the curing temperature of the bio-based IMD ink is lowered, reducing the thermal deformation of the substrate film. Furthermore, the bio-based modified saturated polyester contains a large number of hydroxyl and carboxyl groups, effectively improving adhesion and ductility on the substrate film. The use of bio-based modified saturated polyester makes the bio-based IMD ink more suitable for complex curved substrates and provides microcrack repair capabilities, thus significantly improving the mechanical properties of injection molded products. Moreover, the low VOC emissions of the bio-based modified saturated polyester and the bio-based modified PDI-type curing agent ensure the environmental friendliness of the bio-based IMD ink.

[0110] The following are some specific examples. Where %, it refers to a percentage by weight. It should be noted that the following examples do not exhaustively cover all possible scenarios, and unless otherwise specified, the materials used in the following examples are commercially available.

[0111] Example 1

[0112] Under a stirring speed of 350 r / min, the components of the ink were added to the solvent in the following order: bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets, and adhesion promoter. The mixture was stirred until all components were added. Then, stirring was continued at a speed of 600 r / min to 1000 r / min for 12 minutes. Next, the curing agent was added and stirred until homogeneous at a stirring speed of 850 r / min for 15 minutes. This process was repeated to obtain IMDA ink, IMDB ink, and IMDC ink, which were then ready for use.

[0113] Hexagonal boron nitride nanosheets, KH-560 silane coupling agent, propylene glycol methyl ether acetate, BYK-358N leveling agent and PET4A crosslinking agent were mixed and stirred at a speed of 800 r / min for 18 min to obtain a suspension of hexagonal boron nitride nanosheets for later use.

[0114] The PET film was ultrasonically cleaned with acetone for 6 minutes, then cleaned with deionized water, dried with nitrogen, and finally treated with oxygen plasma for 1.5 minutes at a power of 50W.

[0115] Ink A was applied to the substrate film, and the spin coater was used at a speed of 2000 rpm for 30 seconds to allow ink A to spread and form. Then, it was dried at 65°C for 90 seconds under a nitrogen purging condition of 0.5 MPa. Finally, it was subjected to a 300 mJ / cm² spray. 2 UV cured to 65±2% cure rate, then ink B was added onto ink A layer. The spin coater was operated at 1800 rpm for 35 seconds to allow ink B to spread and form. Next, it was dried at 70°C for 75 seconds under a -0.6 bar vacuum environment. Finally, it was subjected to 350 mJ / cm² curing. 2 UV cured to 65±2% cure rate, then ink C was applied onto ink B layer. The spin coater was operated at 2000 rpm for 20 seconds to allow ink B to spread and form. Next, it was dried under -0.6 bar vacuum with hot air convection at 60°C for 60 seconds using infrared heating. Finally, it was dried using 400 mJ / cm² heat treatment. 2 UV curing to 60%–70% cure rate, followed by adding a hexagonal boron nitride nanosheet suspension to the ink C layer at 23℃–25℃. The spin coater is first set at 800 rpm for 10 seconds to spread the suspension. Then, under a 0.5T–0.6T magnetic field, the speed is controlled at 2500 rpm for 40 seconds to solidify the suspension. Finally, it is dried at 35℃ for 20 minutes in an 8MPa CO2 gas environment, followed by drying under a nitrogen atmosphere at 405nm LED and 100mJ / cm².2 UV curing was performed, followed by control under 385nm LED light and 500mJ / cm² temperature. 2 UV curing was performed, followed by heat curing at 150°C for 5 minutes to obtain an IMD film.

[0116] Comparative Example 1

[0117] The difference from Example 1 is that the amount of hexagonal boron nitride nanosheets added in ink layer A, ink layer B and ink layer C is 15.

[0118] Comparative Example 2

[0119] The difference from Example 1 is that ink layer A is completely cured before ink B is added to ink layer A, ink layer B is completely cured before ink C is added to ink layer B, and ink layer C is completely cured before hexagonal boron nitride nanosheet suspension is added to ink layer C.

[0120] Comparative Example 3

[0121] The difference from Example 1 is that the amount of hexagonal boron nitride nanosheets added in ink layer A, ink layer B and ink layer C is 0.

[0122] Comparative Example 4

[0123] The difference from Example 1 is that the ink C layer was further cured completely, and no hexagonal boron nitride nanosheets were formed on the ink C layer.

[0124] Comparative Example 5

[0125] The difference from Example 1 is that the amount of hexagonal boron nitride nanosheets added in ink layers A, B, and C is 0, and ink layer C is further cured completely without forming a hexagonal boron nitride nanosheet layer on ink layer C.

[0126] The formulations of bio-based IMD inks are shown in Table 1. In each formulation, the mass percentage of hexagonal boron nitride nanosheets in ink layer A is 5%, the mass percentage of hexagonal boron nitride nanosheets in ink layer B is 10%, and the mass percentage of hexagonal boron nitride nanosheets in ink layer C is 30%. The weight unit of each component is kg.

[0127] Table 1: Formulation of Bio-based IMD Inks

[0128]

[0129]

[0130] The IMD films obtained from formulations 1 to 7 using the method in Example 1 were subjected to performance testing. The adhesion test method followed the national standard GB / T 9286-1998; the flexibility test method followed GB / T1731-2020, using a No. 5 shaft rod (3mm diameter) to test the ink flexibility; the elongation at break test method was as follows: the IMD film was preheated to 60℃ for 20 minutes before testing, and then the film layer was tested according to GB / T 1040.3. If the elongation was ≥150%, it was determined that there was no cracking or peeling.

[0131] In the test results, the IMD films obtained by formulations 1 to 5 all showed better adhesion, elongation and elongation at break; in particular, the IMD film obtained by formulation 5 had better adhesion and elongation than the IMD film obtained by formulation 6, and the IMD film obtained by formulation 5 had better adhesion and elongation than the IMD film obtained by formulation 7.

[0132] Formula 5 was used to obtain IMD films using the methods of Example 1 and Comparative Examples 1 to 5. The high temperature resistance test was conducted by using a constant temperature chamber at 320 ± 2°C for 10 seconds, repeated 5 times, and recording whether there was delamination or cracking.

[0133] In the test results, the number of IMD films prepared by the method of Example 1 and the number of IMD films prepared by the methods of Comparative Examples 1 to 5 were all 1000. The IMD films obtained by the method of Example 1 were all free of cracks and fissures. In particular, as shown in Figures 3 to 6, these are all injection molded products obtained by Formula 5. Their surfaces have a strong metallic luster, and the color is evenly distributed across the entire surface. Furthermore, the appearance of the surface presents a sense of integrity, without gaps or cracks, and the visual appearance is relatively smooth and natural. 80% of the IMD films obtained by the method of Comparative Example 1 were moderately cracked; 90% of the IMD films obtained by the method of Comparative Example 2 were slightly cracked; 80% of the IMD films obtained by the method of Comparative Example 3 were moderately cracked; 80% of the IMD films obtained by the method of Comparative Example 4 were moderately cracked; and 70% of the IMD films obtained by the method of Comparative Example 5 were severely cracked.

[0134] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for processing injection-molded products, characterized in that, The process includes the following steps: preparing bio-based IMD ink using a bio-based IMD ink preparation method; printing the bio-based IMD ink onto a substrate film to form an IMD ink layer on the substrate film; insulating the IMD ink layer to form a hexagonal boron nitride nanosheet layer on the side of the IMD ink layer away from the substrate film, thus obtaining an IMD film; and performing in-mold injection molding on the IMD film to obtain an injection-molded product. The printing operation on the substrate film using bio-based IMD ink is specifically as follows: spin-coating ink A onto the substrate film using a spin coater, followed by preheating and drying, and UV curing to 60%~70% cure rate to form ink A layer on the substrate film; and then... A spin coater applies ink B onto ink layer A, followed by preheating and UV curing to 60%–70% cure rate, forming ink layer B on top of ink layer A. A spin coater then applies ink C onto ink layer B, followed by preheating and UV curing to 60%–70% cure rate, forming ink layer C on top of ink layer B. Ink layer C is cured to only 60%–70% cure rate. Hexagonal boron nitride nanosheets are then printed onto the IMD ink layer. The IMD ink layer undergoes a heat insulation process, specifically as follows: At a temperature of 23℃–25℃, a suspension of hexagonal boron nitride nanosheets is added to ink layer C. The spin coater is initially set to 800 rpm for 10 seconds to allow the suspension to spread. Then… Under a magnetic field of 0.5T~0.6T, the speed is controlled at 2500rpm for 40s to induce the horizontal alignment of hexagonal boron nitride nanosheets. Following preheating and drying, UV curing is completed, forming a hexagonal boron nitride nanosheet layer on the ink C layer. The preparation method of the hexagonal boron nitride nanosheet suspension is as follows: Hexagonal boron nitride nanosheets, KH-560 silane coupling agent, propylene glycol methyl ether acetate, BYK-358N leveling agent, and PET4A crosslinking agent are mixed uniformly. The bio-based IMD ink comprises the following components in parts by weight: ink: 50-60 parts bio-based modified saturated polyester; 5-10 parts dispersant; 10-15 parts pigment; 1-2 parts additives; 5-8 parts filler; 20 parts solvent. ~30 parts; 1 to 3 parts of adhesion agent; 10 to 15 parts of curing agent: bio-based modified PDI type curing agent; the curing agent is added to the ink and mixed and coated on the substrate film to form an IMD ink layer; the preparation method of the bio-based IMD ink includes the following steps: obtaining each component of the ink and the curing agent; mixing each component of the ink to obtain the ink; adding the curing agent to the ink for mixing to obtain the bio-based IMD ink; the mixing of each component of the ink is specifically as follows: bio-based modified saturated polyester, dispersant, pigment, additive, filler, hexagonal boron nitride nanosheets and adhesion agent are added to the solvent one by one in sequence for stirring and mixing, followed by grinding and filtration to obtain ink A;Bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets, and adhesion promoter were added to a solvent one by one in sequence and stirred and mixed. Then, the mixture was ground and filtered to obtain ink B. Bio-based modified saturated polyester, dispersant, pigment, additives, filler, hexagonal boron nitride nanosheets, and adhesion promoter were added to a solvent one by one in sequence and stirred and mixed. Then, the mixture was ground and filtered to obtain ink C. The following components in ink A were present in the following mass percentages: bio-based modified saturated polyester 50-60 parts; dispersant 5-10 parts; pigment 10-15 parts; additives 1-2 parts; filler 5-8 parts; solvent 20-30 parts; adhesion promoter 1-3 parts. The hexagonal boron nitride nanosheets in ink A accounted for 2%-5% of the total mass, and the added bio-based modified PDI-type curing agent accounted for 10-15 parts by mass. The following components in ink B were present in the following mass percentages: bio-based modified saturated polyester 50-60 parts... The ink contains: 5-10 parts dispersant; 10-15 parts pigment; 1-2 parts additives; 5-8 parts filler; 20-30 parts solvent; 1-3 parts adhesion agent; and the hexagonal boron nitride nanosheets in ink B are 10%-18% by mass, and the added bio-based modified PDI type curing agent is 10-15 parts by mass. In ink C, the following components are present in the following mass percentages: 50-60 parts bio-based modified saturated polyester; 5-1... 0 parts; pigment 10-15 parts; additives 1-2 parts; filler 5-8 parts; solvent 20-30 parts; adhesion agent 1-3 parts, and the mass percentage of hexagonal boron nitride nanosheets in C ink is 28%-35%, and the mass percentage of added bio-based modified PDI type curing agent is 10-15 parts; the hexagonal boron nitride nanosheet suspension includes the following components in the following mass percentages: hexagonal boron nitride nanosheets 5-8 parts; KH-560 silane coupling agent 0.5-1 part; propylene glycol methyl ether acetate 85-90 parts; BYK-358N leveling agent 0.3-0.5 parts; PET4A crosslinking agent 1-2 parts.

2. The processing method for injection-molded articles according to claim 1, characterized in that, The bio-based modified saturated polyester is Guangzhou Qingtian bio-based modified saturated polyester YM136 and / or Guangzhou Qingtian bio-based modified saturated polyester YM138; and / or, the dispersant is Lubrizol 29000; and / or, the pigment is Orion NX505 carbon black; and / or, the additives include acrylate leveling agents and defoamers; and / or, the filler is talc; and / or, the solvent is propylene glycol diacetate and divalent ester; and / or, the adhesion promoter is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, and 3-mercaptotrimethoxysilane; and / or, the bio-based modified PDI type curing agent is Mitsui Chemicals D-3725N.

3. The processing method for injection-molded articles according to claim 1, characterized in that, The bio-based modified saturated polyester has a molecular weight of 6,000 to 20,000; and / or, the proportion of bio-based molecular weight in the bio-based modified saturated polyester is 40% to 50%; and / or, the proportion of bio-based molecular weight in the bio-based modified PDI type curing agent is 60% to 75%; and / or, the proportion of NCO- molecular weight in the bio-based modified PDI type curing agent is 12% to 16%.

4. The processing method for injection-molded articles according to claim 1, characterized in that, The substrate film is a PC film or a PET film.

5. The processing method for injection-molded articles according to claim 1, characterized in that, Under the condition of stirring speed of 200 r / min to 400 r / min, bio-based modified saturated polyester, dispersant, pigment, additives, filler and adhesion agent are added to the solvent one by one and stirred until all are added. Then, the mixture is stirred and dispersed under the condition of stirring speed of 600 r / min to 1000 r / min; and / or, the particles in the ink are ground until the particle size is less than or equal to 7 μm.

6. The processing method for injection-molded articles according to claim 1, characterized in that, Before the step of performing a heat insulation operation on the IMD ink layer, and after the step of printing the substrate film with the bio-based IMD ink, the processing method of the injection molded article further includes the following step: performing a curing and drying operation on the IMD ink layer.

7. An injection-molded product, characterized in that, The product is obtained by the processing method of any one of claims 1 to 6 for injection molded articles.

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