Ink and preparation method thereof

Abstract

The invention discloses printing ink and a preparation method thereof, and relates to the technical field of printing ink, the printing ink comprises a printing ink main body and a curing agent, the printing ink main body comprises polyester resin, hydroxy acrylic resin, an auxiliary agent, a thixotropic agent, a filler, a pigment and a solvent; wherein the polyester resin comprises branched chain type polyester resin and straight chain type polyester resin. The branched-chain polyester resin and the acrylic resin are compounded, and the straight-chain polyester resin is adopted, so that on one hand, the straight-chain polyester resin and the branched-chain polyester resin have relatively good mixing performance, and on the other hand, the straight-chain polyester resin can uniformly stretch in a mixed system and promote uniform stretching of the acrylic resin in the system; therefore, uniform mixing of the branched polyester resin and the acrylic resin is realized, the general printing ink which can be generally used for multiple substrates such as PMMA (polymethyl methacrylate) plates, PC (polycarbonate) plates, hardened plates and the like is obtained, and the general printing ink has good adhesive force, solvent resistance and insulating property.

Description

Technical Field

[0001] The present invention relates to the technical field of ink, and in particular to an ink and a preparation method thereof. Background Art

[0002] With advances in domestic technology, materials such as PMMA (also known as organic glass due to its high transmittance), PC, PET, or composites of PMMA and PC have found widespread application in many fields, such as mobile phone back covers and medical device screens. However, PMMA and PC also have certain drawbacks, such as poor resistance to abrasion and solvents. If exposed directly to the outside, their service life is limited over time, so they are sometimes treated with surface hardening techniques.

[0003] In hardened board materials, ink adhesion varies due to the polarity of the board material, the degree of hardening of the composite material surface (hardness ranges from 1H to 5H), or the hardening process. High-hardness boards are particularly difficult for ink to adhere directly, making this a difficult issue for the industry to balance. Depending on the actual hardness of the board material, appropriate surface treatment must be applied to the board material surface, or adhesion promoters must be added to the ink to achieve adhesion. For these reasons, in actual board processing, different inks must be formulated specifically for different board materials (hardened and non-hardened). This is not only cumbersome to use, but also carries the risk of ink mixing and low work efficiency. Therefore, it is necessary to provide a universal ink that can be used on such PET, PMMA, PC, composite boards, and their hardened board materials. Summary of the Invention

[0004] The main purpose of the present invention is to provide an ink and a preparation method thereof, aiming to solve the problem that existing inks cannot be used for PET, PMMA, PC and their composite plates and hardened plates.

[0005] To achieve the above object, the present invention provides an ink, comprising an ink main body and a curing agent, wherein the ink main body comprises: polyester resin, hydroxy acrylic resin, additive, thixotropic agent, filler, pigment and solvent;

[0006] The polyester resin includes a branched polyester resin and a linear polyester resin. The molecular weight of the linear polyester resin is 2000 to 8000, and the molecular weight of the hydroxy acrylic resin is 2000 to 5000.

[0007] In one embodiment, in the polyester resin, the mass ratio of the branched polyester resin to the linear polyester resin is (2-5):1; and / or,

[0008] In the ink, the mass ratio of the polyester resin to the hydroxy acrylic resin is (40-70):(5-15).

[0009] In one embodiment, the hydroxyl value of the hydroxy acrylic resin is 50 to 100 mg KOH / g; and / or,

[0010] The branching degree of the branched polyester resin is 3 to 6; and / or,

[0011] The molecular weight of the branched polyester resin is 1W to 3W.

[0012] In one embodiment, the ink body comprises, in parts by mass:

[0013] 40-70 parts of polyester resin, 5-15 parts of hydroxy acrylic resin, 5.6-14 parts of auxiliary agent, 1-3 parts of thixotropic agent, 5-15 parts of pigment, 5-10 parts of filler and 5-45 parts of solvent.

[0014] In one embodiment, in the auxiliary agent, the mass ratio of the dispersant, the defoaming agent and the leveling agent is (5-10): (0.5-3): (1-3).

[0015] In one embodiment, the branched polyester resin has a hydroxyl value of 20 to 50 mg KOH / g; and / or

[0016] The hydroxyl value of the linear polyester resin is 20 to 50 mg KOH / g; and / or,

[0017] The mass ratio of the ink main body to the curing agent is (10-20):1.

[0018] In one embodiment, the pigment comprises at least one of carbon black, titanium dioxide and color powder; and / or,

[0019] The thixotropic agent includes fumed silica, and the fumed silica includes organic-modified fumed silica; and / or,

[0020] The filler comprises at least one of barium sulfate, talc and calcium carbonate; and / or,

[0021] The curing agent includes an isocyanate curing agent; and / or,

[0022] The solvent includes at least one of a ketone solvent and an ester solvent.

[0023] In one embodiment, the auxiliary agent includes at least one of a dispersant, a defoamer, and a leveling agent, wherein:

[0024] The dispersant includes a polyurethane dispersant; and / or,

[0025] The defoaming agent includes a modified polysiloxane defoaming agent; and / or,

[0026] The leveling agent includes a polyacrylate non-silicone leveling agent.

[0027] The present invention also provides a method for preparing the ink as described above, comprising the following steps:

[0028] Mixing polyester resin, acrylic resin, additives and solvent, and dispersing them once to obtain an intermediate mixture;

[0029] The intermediate mixture is mixed with a thixotropic agent, a pigment and a filler, and then dispersed and ground to obtain an ink main body;

[0030] The ink main body is mixed with a curing agent to obtain ink.

[0031] In one embodiment, the primary dispersion speed is 1500-1800 r / min; and / or,

[0032] The time for the primary dispersion is 10 to 15 minutes; and / or,

[0033] The secondary dispersion speed is 1000-1500 r / min; and / or,

[0034] The secondary dispersion time is 10 to 30 minutes; and / or,

[0035] The particle size of the ink main body is less than 5 μm.

[0036] In the technical solution provided by the present invention, the ink comprises a branched polyester resin. The reactive functional groups (such as hydroxyl and carboxyl groups) at the ends of the branches can form hydrogen bonds or ion-dipole interactions with polar groups (such as metal oxides) on the surface of the hardened substrate. During the curing process, the branched structure can provide more crosslinking sites, chemically reacting with the substrate surface or other components in the ink (such as the curing agent) to form a covalent bond network. Therefore, the branched polyester resin can improve the adhesion of the ink to hardened substrates and materials such as PC / PET.

[0037] The ink's main component also includes a hydroxylated acrylic resin. Within the PMMA substrate, the PMMA backbone contains polar ester groups and methyl methacrylate units. The presence of these ester groups creates a highly polar surface. The carbonyl and ether groups in the PMMA molecular chain can form strong interactions with polar substances. The hydroxylated acrylic resin backbone is composed of acrylate monomers, with side chains containing numerous polar functional groups such as hydroxyl and carboxyl groups. These polar functional groups closely match the polarity of PMMA groups, facilitating molecular-level contact between the two interfaces. Consequently, the hydroxylated acrylic resin allows for better ink adhesion to the PMMA sheet.

[0038] The main body of the ink also includes a linear polyester resin. On the one hand, the linear polyester resin can have good mixing performance with the branched polyester resin. On the other hand, the low molecular weight linear polyester resin can be evenly stretched in the mixed system and promote the uniform stretching of the low molecular weight acrylic resin in the system, thereby achieving uniform mixing of the branched polyester resin and acrylic resin mixed system. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. Where the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] Surface modification techniques for hardening sheet materials typically include surface coating hardness modification, surface coating, and surface physical treatment. Surface coating hardness modification involves applying a layer of high-hardness material to the sheet surface to increase its hardness. Typical coating materials include inorganic substances, silicone coatings, fluorocarbon paints, multifunctional acrylates, and small amounts of thermosetting resins. Surface coating (usually performed using PVD) involves applying metals, metal oxides, or other inorganic substances to the sheet surface. Surface physical treatment primarily utilizes lasers and other techniques to alter the sheet surface structure.

[0041] At present, the surface hardening method for the board is still the surface coating process with silicone as the main component and a small amount of metal oxides and other additives as the commonly used process for the surface hardening of PMMA / PC boards.

[0042] PET, PMMA, PC, composite sheets, and their hardened counterparts are currently widely used. However, due to the polarity of the sheets and the varying degrees of surface hardness of the composite materials (hardness ranging from 1H to 5H), surface tension decreases, leading to capillary adhesion. This makes it difficult for printed inks to adhere to the surface, resulting in increased product rejection rates. High-hardness sheets are particularly challenging to achieve direct ink adhesion, requiring appropriate surface treatment or the addition of different resin systems and adhesion promoters tailored to the sheet's actual hardness. For these reasons, the actual sheet processing process often presents risks of ink mixing and results in low efficiency. Therefore, it is essential to provide a universal ink that works well on these materials, including PET, PMMA, PC, their composite sheets, and hardened sheets.

[0043] In view of this, the present invention proposes an ink that can be used for PET, PMMA, PC and their composite substrates and hardened materials.

[0044] The ink provided by the present invention comprises an ink main body and a curing agent, wherein the ink main body comprises: polyester resin, hydroxy acrylic resin, auxiliary agent, thixotropic agent, filler, pigment and solvent;

[0045] The polyester resin includes branched polyester resin and linear polyester resin.

[0046] In the hardened substrate, the linear polyester resin and acrylic resin in the technical solution provided by the present invention effectively wet the surface, while the active functional groups (such as hydroxyl and carboxyl groups) at the end of the branched polyester resin can form hydrogen bonds or ion-dipole interactions with polar groups (such as metal oxides) on the surface of the hardened substrate. During the curing process, the branched structure can provide more cross-linking sites, chemically reacting with the substrate surface or other components in the ink (such as curing agent) to form a covalent bond network. Therefore, it can effectively improve the adhesion of the ink to the hardened substrate and materials such as PC / PET.

[0047] In PMMA substrates, the PMMA backbone contains polar ester groups and methyl methacrylate units. The presence of the ester groups imparts a high degree of surface polarity. The carbonyl and ether oxygen groups in the PMMA molecular chain can form strong interactions with polar substances. Hydroxylated acrylic resins, on the other hand, have a backbone composed of acrylate monomers and side chains containing numerous polar functional groups such as hydroxyl and carboxyl groups. These polar functional groups closely match the polarity of PMMA groups, making molecular-level contact easier at the interface. Consequently, hydroxylated acrylic resins enable better ink adhesion to PMMA sheets.

[0048] However, hydroxy acrylic resins have poor compatibility with branched polyester resins. The present invention, however, adds a linear polyester resin to the main ink, enabling uniform mixing of branched polyester resins, linear polyester resins, and acrylic resin mixtures. The inventors speculate that this may be because, on the one hand, linear polyester resins have better mixing properties with branched polyester resins because they are both polyester resins, and, on the other hand, low-molecular-weight linear polyester resins can spread evenly in the mixture, promoting the uniform spreading of low-molecular-weight acrylic resins in the system, facilitating dispersion and wetting during the pigment grinding process, and forming a uniformly wrapped state. This solves the problem of easy agglomeration of hydroxy acrylic resins when mixed with polyester resins, and achieves uniform mixing of branched polyester resins, linear polyester resins, and acrylic resin mixtures.

[0049] Specifically, the molecular weight of the linear polyester resin can be 2000, 2500, 4000, 6000, 8000, etc., and the molecular weight of the hydroxy acrylic resin can be 2000, 3000, 4000, 5000, etc. On the one hand, the molecular weight of the linear polyester resin in this solution is similar to that of the acrylic resin, and the molecular weight is smaller. On the other hand, the linear low molecular weight (2000-8000) polyester resin has less steric hindrance than the branched resin. Therefore, the low molecular weight hydroxy acrylic resin is physically modified by the medium and low molecular weight linear polyester resin, and then mixed with the highly branched polyester resin to achieve a miscible state, so that the resin molecules are in a stretched state in the microscopic state, which is conducive to dispersion and wetting during the grinding process with the pigment, and forms a uniform wrapping state. This can promote uniform mixing of the acrylic resin and the branched polyester resin. In some embodiments, the molecular weight of the linear polyester resin is 2500-8000.

[0050] Furthermore, the hydroxyl value of the hydroxy acrylic resin is 50-100 mg KOH / g. Within the above range, more hydroxyl groups in the hydroxy acrylic resin can make the hydroxy acrylic resin more polar, less likely to agglomerate in the system, and thus better spread out.

[0051] It is understood that when the hydroxyl value of the hydroxy acrylic resin is 50 to 100 mg KOH / g and the molecular weight of the hydroxy acrylic resin is 2000 to 5000, the hydroxy acrylic resin can have a better stretching state in the system.

[0052] Furthermore, the branched polyester resin has a branching degree of 3 to 6 and a molecular weight of 1W to 3W. Higher branching degrees and molecular weights provide more branched structures and more crosslinking sites, allowing chemical reactions with the substrate surface or other components in the ink to form a covalent bond network. This further improves the ink's adhesion to hardened substrates and materials such as PC / PET.

[0053] In the polyester resin, the mass ratio of the branched polyester resin to the linear polyester resin is (2-5):1; specifically, the mass ratio of the branched polyester resin to the linear polyester resin can be 2:1, 3:1, 4:1, 5:1 or a range consisting of any two of the above values. The linear polyester resin is equivalent to a co-solvent in the system, which promotes the mixing of the branched polyester resin and the hydroxy acrylic resin. Therefore, if too little is added, the effect may not be good. If too much is added, it will lead to dilution of the branched polyester resin, affecting the effect of the branched polyester resin. Therefore, the mass ratio of the branched polyester resin to the linear polyester resin within the above range can make the ink have good mixing uniformity while having good adhesion and excellent solvent resistance.

[0054] In the ink, the mass ratio of the polyester resin to the hydroxy acrylic resin is (40-70):(5-15). Specifically, the mass ratio of the polyester resin to the hydroxy acrylic resin can be 40:5, 50:5, 60:5, 70:5, 40:10, 55:10, 60:10, 70:10, 40:15, 50:15, 60:15, 70:15, or a range consisting of any two of the above values. The mass ratio of the polyester resin to the hydroxy acrylic resin within the above range can take into account the high adhesion of the polyester resin and the high polarity of the acrylic resin, thereby achieving universal application on various board materials.

[0055] Furthermore, the ink main body includes, by mass, 40 to 70 parts of polyester resin, 5 to 15 parts of hydroxy acrylic resin, 5.6 to 14 parts of auxiliary agent, 1 to 3 parts of thixotropic agent, 5 to 15 parts of pigment, 5 to 10 parts of filler and 5 to 45 parts of solvent.

[0056] Furthermore, in some embodiments, the mass ratio of the hydroxy acrylic resin, the linear polyester resin and the branched polyester resin is (5-15): (10-20): (40-50). Within the above range, the ink has good mixing uniformity and good adhesion to various substrates.

[0057] Furthermore, in the auxiliary agent, the mass ratio of the dispersant, the defoaming agent and the leveling agent is (5-10): (0.5-3): (1-3).

[0058] In some embodiments, the hydroxyl value of the branched polyester resin is 20 to 50 mg KOH / g; the hydroxyl value of the linear polyester resin is 20 to 50 mg KOH / g; the hydroxyl value of the branched polyester resin can be 20 mg KOH / g, 30 mg KOH / g, 40 mg KOH / g, 50 mg KOH / g, or a range consisting of any two of the above values; the hydroxyl value of the linear polyester resin can be 20 mg KOH / g, 30 mg KOH / g, 40 mg KOH / g, 50 mg KOH / g, or a range consisting of any two of the above values. The hydroxyl value of the polyester resin affects its crosslinking reactivity with a curing agent (such as isocyanate). Within the above range, the polyester resin has sufficient hydroxyl groups to react with isocyanate groups (-NCO) to form a dense crosslinked network, thereby improving the adhesion, abrasion resistance, and chemical resistance of the ink.

[0059] In some embodiments, the mass ratio of the ink main body and the curing agent is (10-20):1. The mass ratio of the ink main body and the curing agent within the above range can enable the active groups in the ink and the isocyanate groups in the curing agent to fully react, increase the crosslinking density, and enhance the various chemical resistances of the ink.

[0060] It is understood that the ink may further include a dilution solvent, and the dilution solvent may be the same as the solvent in the main body of the ink.

[0061] In some embodiments, the pigment includes at least one of carbon black, titanium dioxide, and color powder. Different pigments can be used for different application scenarios.

[0062] In some embodiments, the thixotropic agent comprises fumed silica, including organic-modified fumed silica. The fumed silica imparts excellent thixotropy (shear-thinning properties) to the resulting ink. When the ink is stationary, a three-dimensional hydrogen bond network forms on the surface of the silica particles, increasing the system's viscosity and preventing pigment sedimentation and sagging. When process shear forces (such as during printing) are applied, the network structure is disrupted, reducing viscosity and ensuring uniform ink flow. After shearing ceases, hydrogen bonds are rapidly reestablished, restoring viscosity and preventing excessive leveling after printing.

[0063] In some embodiments, the filler includes at least one of barium sulfate, talc, and calcium carbonate; and the curing agent includes an isocyanate curing agent.

[0064] In some embodiments, the solvent comprises at least one of a ketone solvent and an ester solvent. When a ketone solvent is used, it not only has a stronger ability to dissolve the surface of the substrate, but also has a high boiling point and a slow volatilization and drying speed, which is beneficial for ink printing.

[0065] In some embodiments, the auxiliary agent includes at least one of a dispersant, a defoamer, and a leveling agent, wherein the dispersant includes a polyurethane dispersant; the defoamer includes a modified polysiloxane defoamer; and the leveling agent includes a polyacrylate non-silicone leveling agent.

[0066] The present invention also provides a method for preparing the ink as described above, the method comprising the following steps:

[0067] Mixing polyester resin, acrylic resin, additives and solvent, and dispersing them once to obtain an intermediate mixture;

[0068] The polyester resin, acrylic resin, additives, and solvent can be uniformly mixed by primary dispersion. In some embodiments, the primary dispersion speed is 1500-1800 r / min; the primary dispersion time is 10-15 minutes; specifically, the primary dispersion speed can be 1500 r / min, 1600 r / min, 1700 r / min, 1800 r / min, etc.; the primary dispersion time is 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, etc. High-speed rotation dispersion can improve the mixing uniformity of the intermediate mixture.

[0069] The intermediate mixture is mixed with a thixotropic agent, a pigment and a filler, and then dispersed and ground to obtain an ink main body;

[0070] The ink main body is mixed with a curing agent to obtain ink.

[0071] The intermediate mixture can be more fully mixed with solid powders such as thixotropic agents, pigments and fillers through secondary dispersion.

[0072] In some embodiments, the rotation speed of the secondary dispersion is 1000-1500 r / min; and the time of the secondary dispersion is 10-30 min.

[0073] In some embodiments, the particle size of the ink body is less than 5 μm. Smaller ink particle size can improve pigment dispersion uniformity, reduce agglomeration, enhance ink stability, reduce edge jaggedness, reduce ink layer surface roughness, and enhance gloss and wear resistance.

[0074] It is understood that the particle size of the ink can be controlled by controlling the grinding conditions. For example, in some embodiments, the secondary dispersed mixture can be ground 3-5 times in a horizontal three-roll mill or 1-2 times in a sand mill.

[0075] It is understood that when using, the ink body is mixed with the curing agent and the diluent and is ready for use. The ink can be printed onto the substrate surface by screen printing, and the printing thickness can be 8 to 15 μm. After drying, the ink coating on the substrate surface is completed.

[0076] The present invention proposes the above technical solution based on the problem that existing inks cannot be used for boards of different hardness (hardened substrates and non-hardened substrates). Polyester resin and acrylic resin are originally incompatible. However, low molecular weight hydroxy acrylic resin is physically modified by medium and low molecular weight straight-chain polyester resin, and then miscible with highly branched medium and high molecular weight resin. As a result, the resin molecules are in a stretched state in the microscopic state, which is conducive to dispersion and wetting during the grinding process with the pigment, and forms a uniform wrapped state. For PMMA substrates, the acrylic resin in the ink can be matched with it to form a stable anchoring effect, thereby improving adhesion; for hardened board materials, in addition to using strong ketone solvents for etching, medium and low molecular weight straight-chain polyester resins and acrylic resins are used to effectively wet the surface, thereby providing effective anchoring for the dense and stable ink layer formed on the surface by the highly branched polyester resin, thereby improving adhesion.

[0077] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0078] Some raw material parameters in the examples and comparative examples of the present invention are as follows:

[0079] Isocyanate curing agent: Model 110N purchased from Mitsui Chemicals, with an NCO content of 11%;

[0080] Defoaming agent: Foamex 810 model purchased from Digo Company;

[0081] Dispersant: BYK-163 purchased from BYK;

[0082] Leveling agent: TEGO Flow300 purchased from Digo Company;

[0083] Pigment: Model 1255P purchased from Bora;

[0084] Modified fumed silica: R972 purchased from Evonik.

[0085] Example 1

[0086] Provided is an ink, which includes, by mass, an ink main body, a curing agent, and a diluent. The ink main body includes, by mass, 50 parts of a branched polyester resin (Toyobo GK360), 10 parts of a linear polyester resin (Toyobo 220), 5 parts of a hydroxy acrylic resin (Shunying SY-7567), 8 parts of a dispersant (BYK-163), 2 parts of a defoaming agent (foamex810), 1 part of a leveling agent (TEGO Flow300), 1 part of a thixotropic agent (modified fumed silica), 12 parts of a pigment (Bora 1255P carbon black), 5 parts of a filler (barium sulfate), and 6 parts of a solvent (isophorone).

[0087] The preparation method of the ink body is as follows:

[0088] placing a branched polyester resin and a linear polyester resin in a reaction kettle and mixing them to obtain a polyester mixed resin;

[0089] Add the polyester mixed resin, hydroxy acrylic resin, dispersant, defoamer, leveling agent and solvent isophorone into a dispersing apparatus and disperse at 1600 r / min for 12 minutes to obtain an intermediate mixture;

[0090] The intermediate mixture, pigment, BaSO4 filler and fumed silica were mixed and transferred to a disperser for dispersion at 1200 r / min for 20 min, and then transferred to a sand mill for grinding at 50° C. for 20 min to obtain an ink body with a fineness of ≤5 μm;

[0091] 100 parts by mass of the ink main body, 10 parts by mass of an isocyanate curing agent, and 10 parts by mass of an isophorone diluent were mixed to obtain an ink.

[0092] Examples 2 to 7 and Comparative Examples 1 to 5 were prepared using similar steps to Example 1. The differences are shown in Table 1.

[0093] The difference between Examples 2 to 4 and Example 1 is that the mass fractions of the branched polyester resin, the linear polyester resin and the hydroxy acrylic resin are different. The specific parameters are shown in Table 1.

[0094] The difference between Example 5 and Example 1 is that the specific substances of the branched polyester resin and the hydroxy acrylic resin are different. The specific parameters are shown in Table 1.

[0095] The difference between Example 6 and Example 1 is that a linear polyester resin with a molecular weight of 10,000 is used. The specific parameters are shown in Table 1.

[0096] The difference between Example 7 and Example 1 is that a hydroxy acrylic resin with a molecular weight of 12,000 is used. The specific parameters are shown in Table 1.

[0097] The difference between Comparative Example 1 and Example 1 is that no linear polyester resin is added, and the total mass proportion of the polyester resin and the hydroxy acrylic resin in the main body of the ink is kept unchanged. Specific parameters are shown in Table 1.

[0098] The difference between Comparative Example 2 and Example 1 is that no branched polyester resin is added, and the total mass proportion of the polyester resin and the hydroxy acrylic resin in the main body of the ink is kept unchanged. Specific parameters are shown in Table 1.

[0099] The difference between Comparative Example 3 and Example 1 is that no hydroxy acrylic resin is added, and the total mass proportion of the polyester resin and the hydroxy acrylic resin in the main body of the ink is kept unchanged. Specific parameters are shown in Table 1.

[0100] The difference between Comparative Example 4 and Example 1 is that a linear polyester resin with a molecular weight of 10,000 is used. The specific parameters are shown in Table 1.

[0101] The difference between Comparative Example 5 and Example 1 is that a hydroxy acrylic resin with a molecular weight of 12,000 is used. The specific parameters are shown in Table 1.

[0102] Table 1 Ink parameters of Examples 1 to 7 and Comparative Examples 1 to 5

[0103]

[0104] Performance Testing

[0105] The inks prepared in Examples 1 to 7 and Comparative Examples 1 to 5 were respectively printed by screen printing (mesh count: 300 mesh) on bare PET, PMMA, PC, the PC surface of PMMA and PC composite boards, hardened PMMA (purchased from Yimi High-tech Materials Technology Co., Ltd.) and hardened PC (purchased from Yimi High-tech Materials Technology Co., Ltd.) boards. The printing was performed once, and the printed film thickness was 5-10 μm. After printing, the inks were baked at 70°C for 60 minutes. After drying, the following performance tests were performed. The results are shown in Tables 2 and 3.

[0106] Grid test: When the total film thickness of the paint coating is 0-60 μm, use a sharp blade (blade angle of 20°-30°, blade thickness of 0.43±0.03mm) to draw 10×10 1mm×1mm small grids on the surface of the test sample; when the total film thickness of the coating is above 60 μm, draw 5×5 2mm×2mm small grids on the surface of the test sample, and each line should be deep enough to reach the bottom layer of the coating; use a brush to clean the debris in the test area; use a tape with an adhesion of (10±1) N / 25mm (NICHIBAN Use CT405AP-24 adhesive tape to firmly adhere to the small grid under test. Use your fingernail to squeeze the tape (be careful not to damage it) to dislodge any bubbles between the tape and the coating, thereby increasing the contact area and strength between the tape and the test area. After 90 ± 30 seconds, grasp one end of the tape and pull it off in the opposite direction at a 60-degree angle within 0.5 to 1 second. Repeat the test once. Afterwards, use a 5x magnifying glass to inspect the paint coating for signs of shedding.

[0107] Water-Boiled 100-grid Test: Boil the sample in pure water at 80°C ± 2°C for 30 minutes. Leave at room temperature for 2 hours before testing adhesion. The test method is the same as the dry 100-grid test.

[0108] Resistance test: resistance meter, 1000V voltage, test at a distance of 10mm between the pen tip and the ink surface. The ink surface resistance is >200GΩ, which is qualified.

[0109] Alcohol resistance test: alcohol concentration is 95%, control the alcohol flow, keep the flannel moist, load 500 grams, rub back and forth on the sample surface 40 times at a frequency of 50 times per minute. It is qualified if the ink does not fade or show through. The number of times the ink fades or shows through is the alcohol resistance limit.

[0110] Table 2 Test results of inks prepared in Examples 1 to 7 and Comparative Examples 1 to 3 on PET, PMMA, and PC sheets

[0111]

[0112]

[0113] Among them: In Comparative Example 1, due to the poor compatibility of the resin, the ink surface was smoothie-like after being prepared, and the screen could not be properly lowered during screen printing, so there was no test data;

[0114] In Comparative Example 3, since the ink had no adhesion to PMMA, the resistance could not be tested, and thus no resistance data was obtained. In the alcohol resistance test, the ink layer fell off.

[0115] Table 3 Test results of inks prepared in Examples 1 to 7 and Comparative Examples 1 to 5 on composite boards, hardened PMMA and hardened PC boards

[0116]

[0117]

[0118] As can be seen from Tables 2 and 3, the inks obtained by using branched polyester resin, linear polyester resin and hydroxy acrylic resin in Examples 1 to 5 have good adhesion on all boards, and have a resistance greater than 200 GΩ and good solvent resistance.

[0119] In Comparative Example 1, no linear polyester resin was added. Since the branched polyester resin had poor compatibility with the acrylic resin, the ink surface showed a smoothie-like appearance after being prepared, and could not be screen-printed.

[0120] The ink obtained in Comparative Example 2 without adding branched polyester resin has good dry water grid and resistance properties on bare PET, PMMA, PC and PC surface of PMMA and PC composite board. However, the adhesion on hardened PMMA and hardened PC boards is poor, not reaching 5B. In addition, the ink obtained in Comparative Example 2 without adding branched polyester resin has poor alcohol resistance (<20 times) when printed on various boards.

[0121] The ink obtained in Comparative Example 3 without adding hydroxyl acrylic resin has good dry water grid and resistance properties on bare PET, PC, and the PC surface of PMMA and PC composite boards. However, its adhesion on hardened PMMA and hardened PC boards is poor, not reaching 5B; and its adhesion on bare PMMA boards is extremely poor.

[0122] In Comparative Example 4, the linear polyester resin had a molecular weight of 10,000, resulting in poor adhesion to all substrates. In Comparative Example 5, the hydroxylated acrylic resin had a molecular weight of 12,000, resulting in poor adhesion to all substrates, with resistance test results of less than 200 GΩ. In contrast, in Examples 1-5, the linear polyester resin had a molecular weight of 2,000-8,000, and the hydroxylated acrylic resin had a molecular weight of 2,000-5,000. The resulting inks exhibited good adhesion to all substrates, high resistance, and excellent solvent resistance.

[0123] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An ink, characterized in that: The ink comprises an ink main body and a curing agent, wherein the ink main body comprises: polyester resin, hydroxy acrylic resin, additives, thixotropic agent, filler, pigment and solvent; The polyester resin includes a branched polyester resin and a linear polyester resin. The molecular weight of the linear polyester resin is 2000 to 8000, and the molecular weight of the hydroxy acrylic resin is 2000 to 5000.

2. The ink according to claim 1, wherein In the polyester resin, the mass ratio of the branched polyester resin to the linear polyester resin is (2-5):1; and / or, In the ink, the mass ratio of the polyester resin to the hydroxy acrylic resin is (40-70):(5-15).

3. The ink according to claim 1, wherein The hydroxy value of the hydroxy acrylic resin is 50 to 100 mg KOH / g; and / or The branching degree of the branched polyester resin is 3 to 6; and / or, The molecular weight of the branched polyester resin is 1W to 3W.

4. The ink according to claim 1, wherein In parts by mass, the ink body comprises: 40-70 parts of polyester resin, 5-15 parts of hydroxy acrylic resin, 5.6-14 parts of auxiliary agent, 1-3 parts of thixotropic agent, 5-15 parts of pigment, 5-10 parts of filler and 5-45 parts of solvent.

5. The ink according to claim 4, wherein In the auxiliary agent, the mass ratio of the dispersant, the defoaming agent and the leveling agent is (5-10): (0.5-3): (1-3).

6. The ink according to claim 1, wherein The branched polyester resin has a hydroxyl value of 20 to 50 mg KOH / g; and / or The hydroxyl value of the linear polyester resin is 20 to 50 mg KOH / g; and / or, The mass ratio of the ink main body to the curing agent is (10-20):

1.

7. The ink according to claim 4, wherein The pigment includes at least one of carbon black, titanium dioxide and color powder; and / or, The thixotropic agent includes fumed silica, and the fumed silica includes organic-modified fumed silica; and / or, The filler comprises at least one of barium sulfate, talc and calcium carbonate; and / or, The curing agent includes an isocyanate curing agent; and / or, The solvent includes at least one of a ketone solvent and an ester solvent.

8. The ink according to claim 4, wherein The auxiliary agent includes at least one of a dispersant, a defoamer and a leveling agent, wherein: The dispersant includes a polyurethane dispersant; and / or, The defoaming agent includes a modified polysiloxane defoaming agent; and / or, The leveling agent includes a polyacrylate non-silicone leveling agent.

9. A method for preparing the ink according to any one of claims 1 to 8, characterized in that: The following steps are involved: Mixing polyester resin, acrylic resin, additives and solvent, and dispersing them once to obtain an intermediate mixture; The intermediate mixture is mixed with a thixotropic agent, a pigment and a filler, and then dispersed and ground to obtain an ink main body; The ink main body is mixed with a curing agent to obtain ink.

10. The method for preparing the ink according to claim 9, wherein: The primary dispersion speed is 1500-1800 r / min; and / or, The time for the primary dispersion is 10 to 15 minutes; and / or, The secondary dispersion speed is 1000-1500 r / min; and / or, The secondary dispersion time is 10 to 30 minutes; and / or, The particle size of the ink main body is less than 5 μm.

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