Printing ink for recess printing of a veneer, method of preparation and use thereof

Abstract

Embodiments of the present application provide a printing ink for veneer intaglio embossing, a preparation method and applications thereof, and belong to the technical field of printing ink. The printing ink comprises, by weight parts, in the first component, solvent: 20-30 parts, monomer: 4-6 parts, photoinitiator: 3-6 parts, oxygen polymerization inhibitor: 0.1-0.2 parts, special modified dual-curing aliphatic polyurethane acrylate: 35-55 parts, fluorosilicon modified aliphatic polyurethane acrylate: 15-25 parts, nano-hybrid modified high-functionality acrylate: 8-16 parts, defoamer: 0.3-1 part, filler: 6-10 parts; the second component is a curing agent: 5-10 parts; the first component is mixed with the second component before coating, and the ink coating is formed after secondary curing after coating. The printing ink has the properties of embossing flexibility and plasticity and wear resistance and stain resistance after curing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printing ink, in particular to a printing ink for embossed pressing of a veneer panel, a preparation method and application thereof. BACKGROUND

[0002] In the field of decorative panels, synchronous pressing of veneer panels is an advanced process that aligns the texture of veneer paper and pressing steel plate through high-definition photography and precise positioning, giving the panel a natural texture close to natural wood in both vision and touch. The finished veneer panel, i.e. ecological board, has the advantages of wear resistance, pollution resistance, moisture resistance, etc., and the texture is three-dimensional and the touch is realistic.

[0003] However, the existing UV printing ink has obvious defects when adapting to the synchronous pressing process of veneer panels. For example, the existing ink has high hardness after curing, good scratch resistance and wear resistance, but lacks flexibility, which makes it unable to form clear concave-convex texture during the pressing process, and the finished product surface cannot form three-dimensional texture close to natural wood. For another example, the UV coating of PVC blister or the skin feel coating of water-based PUD sacrifices hardness, wear resistance and stain resistance to a certain extent to meet the pressing flexibility requirement, although good stretchability is obtained, but the scratch resistance, stain resistance and moisture resistance are insufficient and the durability is poor.

[0004] Therefore, a new printing ink for embossed pressing of a veneer panel, a preparation method and application thereof are proposed to solve the above problems. SUMMARY

[0005] In order to solve at least one aspect of the above problems and defects in the prior art, embodiments of the present application provide a printing ink for embossed pressing of a veneer panel, a preparation method and application thereof, which is a two-component system by separating a specific resin system (preparing special modified double-cured aliphatic polyurethane acrylate, three-functional fluorosilicon modified aliphatic polyurethane acrylate and nano-hybrid modified high-functionality acrylate) from a curing agent and performing secondary distribution curing, and first obtaining an initial cross-linked network through thermal curing to adapt to the stretching and mold pressing of the pressing process to ensure clear and delicate pressing, and then greatly improving the cross-linking density through UV curing to obtain high hardness, realizing that the ink coating has excellent flexibility, plasticity and wear and stain resistance. The technical solution is as follows:

[0006] According to one aspect of the present application, a printing ink for embossed pressing of a veneer panel is provided, which comprises a first component and a second component, and the specific components are as follows in weight parts:

[0007] In the first component,

[0008] Solvent: 20-30 parts;

[0009] Monomer: 4-6 parts;

[0010] Photoinitiator: 3-6 parts;

[0011] Oxygen inhibitor: 0.1-0.2 parts;

[0012] Special modified dual-curing aliphatic polyurethane acrylate: 35-55 parts;

[0013] Fluorosilicon modified aliphatic polyurethane acrylate: 15-25 parts;

[0014] Nanohybrid modified high-functionality acrylate: 8-16 parts;

[0015] Defoaming agent: 0.3-1 part;

[0016] Filler: 6-10 parts;

[0017] In the second component,

[0018] Curing agent: 5-10 parts;

[0019] The first component is mixed with the second component before coating, and the ink coating is formed after secondary curing after coating.

[0020] In some embodiments, the viscosity of the special modified dual-curing aliphatic polyurethane acrylate is 35,000-48,000 cps at 25°C, the solid content is 60%-70%, the hydroxyl value is 12-20 mg KOH / g, and the functional group is 3.

[0021] In some embodiments, the fluorosilicon modified aliphatic polyurethane acrylate is a trifunctional polyurethane acrylate.

[0022] In some embodiments, the viscosity of the nanohybrid modified high-functionality acrylate is 500-1,500 cps at 25°C, the solid content is 80%-90%, and the functional group is 9-10.

[0023] According to another aspect of the present application, a preparation method of a printing ink for embossing of a decorative panel is provided. The preparation method is used to prepare the printing ink described in the above aspect. The preparation method specifically comprises the following steps:

[0024] Step S110: Take 50wt% of the solvent and add the photoinitiator, stir until completely dissolved, and then filter out impurities to obtain a mixed solution;

[0025] Step S120: Take the remaining 50wt% of the solvent and add the monomer and the special modified dual-curing aliphatic polyurethane acrylate, and disperse until the special modified dual-curing aliphatic polyurethane acrylate is completely dissolved to obtain a resin solution;

[0026] Step S130: mixing the mixed solution and the resin solution, adding fluorosilicon modified aliphatic polyurethane acrylate and nano hybrid modified high functionality acrylate in sequence, adding fillers after stirring and mixing uniformly, and continuously stirring to obtain a slurry;

[0027] Step S140: grinding the slurry to a fineness of ≤5 μm;

[0028] Step S150: adding an oxygen inhibitor and a defoaming agent, stirring uniformly at a stirring speed of 600-1000 r / min, and then filtering (for example, filtering through 300 mesh cloth) to obtain a first component.

[0029] In some embodiments, preferably, the preparation method further comprises pre-preparing a special modified dual-cured alicyclic polyurethane acrylate, and the specific steps include:

[0030] Step S210: uniformly mixing 25-40 parts by weight of aliphatic polyurethane tetraacrylate prepolymer and 55-65 parts by weight of a mixed solvent of ethyl acetate and toluene, wherein the weight ratio of ethyl acetate to toluene is 1:2;

[0031] Step S220: after being warmed to 50-60°C, adding dicyclohexylmethane diisocyanate and dibutyl tin laurate within 30 minutes, and maintaining the temperature for 80-100 minutes of reaction;

[0032] Step S230: after the -NCO value reaches a preset value (about 0.1-0.2% of -NCO group content), warming to 60-70°C and adding hydroxy acrylate, dibutyl tin laurate and hydroquinone dropwise within 2 hours;

[0033] Step S240: continuously warming to 75-85°C for stirring reaction for 100-200 minutes, adding triethylamine to neutralize the reaction for 25-35 minutes when the -NCO group content is monitored to be ≤0.1%, and obtaining the special modified dual-cured alicyclic polyurethane acrylate.

[0034] In some embodiments, the viscosity of the aliphatic polyurethane tetraacrylate prepolymer is 5500-15000 cps@25°C, the solid content is 70-80%, the hydroxyl value is 20-30 mg KOH / g, and the functional group is 4.

[0035] In some embodiments, in step S220, the dicyclohexylmethane diisocyanate is 16-20 parts by weight, and the weight of the dibutyl tin laurate is 0.15-0.25wt% of the weight of the aliphatic polyurethane tetraacrylate prepolymer.

[0036] In some embodiments, in step S230, the weight ratio of the hydroxy acrylate is 8-12 parts, the weight ratio of the mixture of hydroxyethyl methacrylate, trimethylolpropane diacrylate and pentaerythritol triacrylate is 1:2:2, the weight of dibutyltin laurate is 0.1-0.2wt% of the weight of the hydroxy acrylate, and the weight of hydroquinone is 0.05-0.15wt% of the weight of the hydroxy acrylate.

[0037] According to another aspect of the present application, there is provided an application of a printing ink in embossing of a veneer. The printing ink is the printing ink described in the above aspect or obtained by the preparation method described in the above aspect.

[0038] In some embodiments, the first component, the second component and the diluent are mixed in a weight ratio of 95-105:8-12:25-35, filtered and then coated on the surface of the veneer paper; dried at a temperature of 110-130℃ for 1-3 minutes until tack-free; the dried veneer paper is hot-pressed with the board through a die steel plate at a temperature of 220-260℃ for 2-3 minutes to complete the lamination and embossing to obtain a composite board; and the composite board is UV cured with a UV energy range of 600-800mJ / cm 2 The ink coating is formed.

[0039] The printing ink for embossing of a veneer, the preparation method and the application thereof provided by the embodiments of the present application have at least one or part of the following advantages:

[0040] (1) The resin system and the curing agent are separated into a two-component system and are subjected to secondary distribution curing, the initial crosslinking network is obtained through thermal curing to adapt to the stretching and die pressing of the embossing process to ensure clear and delicate embossing, and the crosslinking density is greatly improved through UV curing to obtain high hardness, so that the ink coating has excellent flexibility, plasticity, wear resistance and stain resistance;

[0041] (2) The special modified dual-curing alicyclic polyurethane acrylate is prepared in advance, so that the resin system has both heat-curable hydroxyl groups and UV-curable acrylate double bonds, and the specific viscosity, hydroxyl value and functional group ensure that the resin system can effectively react with the curing agent in the thermal curing stage and rapidly participate in the reaction in the UV curing stage;

[0042] (3) The fluorosilicon-modified aliphatic polyurethane acrylate with a trifunctional group is used to introduce fluorine and silicon segments with low surface energy into the ink coating system, so that the ink coating has persistent skin-like smoothness, excellent graffiti resistance and stain resistance, and stains can be easily removed without residue;

[0043] (4) By using nano-hybrid modified high-functionality acrylate with high functional groups, the wear resistance and surface hardness of the ink coating can be significantly enhanced. The high-functionality helps to form a highly dense crosslinking network during UV curing, combined with the dispersion reinforcement effect of nanoparticles, so that the ink coating can withstand 8800 times of friction test, far exceeding conventional products, greatly extending the service life of the product;

[0044] (5) By controlling specific process parameters such as fineness, filtration, etc. in the preparation process, the density and integrity of the ink coating can be effectively ensured, avoiding defects such as pinholes, so as to ensure the dirt resistance and moisture resistance of the printing ink;

[0045] (6) The printing ink of the present application can maintain stable performance after high temperature and humidity test (120 hours at 85℃ and 85% RH) for decorative panel intaglio embossing, and has excellent weather resistance and environmental adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0046] These and / or other aspects and advantages of the present application will become apparent and be more readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0047] Figure 1 Product state diagram after the printing ink according to one embodiment of the present application is coated on a decorative panel and cured;

[0048] Figure 2 Step flowchart of the preparation method of the printing ink for decorative panel intaglio embossing according to one embodiment of the present application;

[0049] Figure 3 Step flowchart of the preparation of the special modified dual-cured alicyclic polyurethane acrylate in the preparation method according to one embodiment of the present application;

[0050] Figure 4 Schematic diagram of the texture effect of the existing coating product UV matte oil dirt-resistant coating after molding;

[0051] Figure 5 Schematic diagram of the dirt-resistant test effect of the existing coating product oily low-temperature baking paint;

[0052] Figure 6 Schematic diagram of the dirt-resistant test effect of the printing ink prepared according to embodiment 3 of the present application after curing on a decorative panel. DETAILED DESCRIPTION

[0053] The technical solutions of the present application are further specifically explained below by examples in combination with the drawings. In the description, same or similar reference numerals indicate same or similar components. The following description of the embodiments of the present application with reference to the drawings is intended to explain the general inventive concept of the present application, and should not be understood as a limitation of the present application.

[0054] The present application provides a printing ink for embossed veneer, which is a two-component system separated from a curing agent by a specific resin system (preparation of special modified double-cured alicyclic polyurethane acrylate, trifunctional fluorosilicon modified aliphatic polyurethane acrylate and nano-hybrid modified high-functionality acrylate) and secondary distribution curing, and is first heat-cured to obtain an initial cross-linked network to adapt to the stretching and molding of the embossing process to ensure clear and delicate embossing, and then UV-cured to greatly increase the cross-linking density to obtain high hardness, realizing that the ink coating has excellent flexibility, plasticity and wear resistance and stain resistance.

[0055] According to one aspect of the present application, a printing ink for embossed veneer is provided, comprising a first component and a second component, and the specific components are as follows in parts by weight:

[0056] In the first component,

[0057] Solvent: 20-30 parts;

[0058] Monomer: 4-6 parts;

[0059] Photoinitiator: 3-6 parts;

[0060] Oxygen inhibitor: 0.1-0.2 parts;

[0061] Special modified double-cured alicyclic polyurethane acrylate: 35-55 parts;

[0062] Fluorosilicon modified aliphatic polyurethane acrylate: 15-25 parts;

[0063] Nano-hybrid modified high-functionality acrylate: 8-16 parts;

[0064] Defoamer: 0.3-1 part;

[0065] Filler: 6-10 parts;

[0066] In the second component,

[0067] Curing agent: 5-10 parts;

[0068] In use, the first component is mixed with the second component before coating, and the ink coating is formed after secondary curing after coating, wherein the secondary curing includes first heat curing for embossing and then UV curing for final coating curing.

[0069] Exemplarily, the selection of other necessary components in the printing ink composition, except for the specific resin system, is as follows:

[0070] The solvent is used to disperse the initial resin mixture by mixing with the resin system during the preparation of the printing ink. Generally, the solvent can be selected from one of acetic ether, butyl acetate, butanone, PMA, PM, IPA, or a mixture of two or more thereof. The main role of the solvent is to adjust the viscosity of the printing ink, so that it is suitable for gravure embossing printing, and to volatilize during the heat curing baking stage to form a dry paint film.

[0071] The monomer is usually used as a kind of active diluent, which participates in the photocuring reaction to adjust the functionality and crosslinking density of the resin system. The monomer can be selected from one of HDDA (with di-functionality, high reactivity, providing abundant crosslinking points), DPHA (with high functionality, improving curing speed and hardness), TPGDA (with the function of balancing dilution and flexibility), or a mixture of two or more thereof.

[0072] The photoinitiator can be selected from a mixture of TPO (2,4,6-trimethylbenzoyl-diphenyl phosphine oxide) and 184 (1-hydroxy-cyclohexyl-phenyl ketone). Among them, TPO has good deep curing effect, 184 has strong surface curing ability, and the two can synergistically act to ensure that the ink coating realizes rapid and thorough synchronous curing inside and outside the resin system under UV curing light.

[0073] The oxygen inhibitor preferably uses Doublecure® PI (tris (N-nitroso-N-phenyl hydroxylamine) aluminum salt). It can effectively inhibit the polymerization inhibition effect of oxygen in the air on the UV curing reaction, and also effectively prevent the self-polymerization of the printing ink during storage, ensuring the stability of the resin system.

[0074] The defoamer preferably uses Huaxia Additives HX-2080. Generally, the defoamer is used to eliminate the bubbles generated during the production and application of the printing ink, to avoid the formation of pinholes, sand holes and other defects in the ink coating, to ensure the density and integrity of the coating, and thus to ensure that the wear resistance, stain resistance, moisture resistance and other properties of the coating are not affected.

[0075] The filler preferably uses spherical aluminum oxide powder with a particle size D50 of 2-4 μm, preferably 3 μm, and a particle size D90 of 4-6 μm, preferably 5 μm. The main role of the filler is to provide a smooth and uniform matting effect for the printing ink, achieving a matte finish. On the other hand, it serves as a hard particle component to significantly improve the wear resistance and scratch resistance of the ink coating.

[0076] Exemplarily, in the second component, the curing agent is mixed with the first component before coating for subsequent secondary curing to form an ink coating layer meeting the performance requirements of the embossed veneer. Generally, the curing agent can be selected from Mitsui Chemical D-160N (belonging to HDI adduct, improving flexibility), D-120N (belonging to H6XDI adduct, having high reactivity to provide excellent adhesion and weather resistance) or D-110N (belonging to XDI adduct, having higher reactivity to improve curing speed and provide excellent weather resistance and color fastness). When the printing ink is used, the curing agent is first mixed with the first component, which helps to occur thermal crosslinking reaction with the hydroxyl group of the special resin in the first component, and is the key to form the first heavy curing network.

[0077] In one example, the special resin system of the printing ink mainly consists of a specially modified double-curing alicyclic polyurethane acrylate, a fluorosilicon-modified aliphatic polyurethane acrylate and a nano-hybrid modified high-functionality acrylate.

[0078] Specifically, the viscosity of the specially modified double-curing alicyclic polyurethane acrylate is 35,000-48,000 cps at 25°C, the solid content is 60%-70%, the hydroxyl value is 12-20 mg KOH / g, and the functional group is 3. Its molecular structure contains both heat-curable hydroxyl groups (-OH) and UV-curable acrylic double bonds.

[0079] The viscosity and solid content directly affect the coating applicability and final film thickness of the printing ink. The hydroxyl value determines the crosslinking density of the reaction between the first component and the curing agent, which in turn affects the mechanical properties of the ink coating layer after thermal curing. The functional group of 3 ensures moderate reactivity and crosslinking ability during the UV curing stage.

[0080] In the thermal curing stage, its hydroxyl group reacts with the isocyanate (-NCO) in the second component curing agent to form a preliminary crosslinking network, which can provide good flexibility and plasticity to the printing ink coating layer, and the elongation rate can reach more than 300%, to meet the requirements of the embossing process of the veneer.

[0081] In the subsequent UV curing stage, its acrylic double bond is excited to participate in free radical polymerization, further greatly improving the crosslinking density, so that the printing ink coating layer obtains high hardness and high wear resistance. The core of the synergistic effect is that through the step-by-step curing mechanism, the contradiction between the “process flexibility” required by the embossing process and the “final rigidity” required by the finished product is solved.

[0082] Specifically, the fluorosilicon-modified aliphatic polyurethane acrylate is a trifunctional polyurethane acrylate. Preferably, the fluorosilicon-modified aliphatic polyurethane acrylate uses OCS FSP 8468 (viscosity cps@60℃ 3300-4000, solid content 100%) or LUCURE 8696 (viscosity cps@25℃ 2000-3000, solid content 100%).

[0083] The ingredient introduces low-surface-energy fluorine and silicon segments, which can significantly reduce the surface tension of the printed ink coating, so that the cured ink coating can maintain a smooth feel for a long time, while also having excellent resistance to graffiti and stain resistance, especially for oily pigment ink, which can be effectively erased.

[0084] The trifunctional product is selected to ensure flexibility while providing sufficient crosslinking points to synergistically cure with other components of the resin system, avoiding excessive reduction in hardness due to the introduction of fluorine and silicon segments. Its unique fluorine and silicon structure is the core of obtaining low surface energy and excellent stain resistance, contributing to effective crosslinking points during UV curing, which helps to improve UV curing hardness and curing speed.

[0085] Specifically, the viscosity of the nano-hybrid modified high-functionality acrylate is 500-1500 cps@25℃, the solid content is 80%-90%, and the functional group is 9-10. Preferably, Hao Hui CR 91093 (functional group 10) or CR 90822-1 (functional group 9) is used.

[0086] This ingredient is a high-functionality nano-composite resin, and its high functionality means that it can form an extremely dense crosslinking network inside the printed ink during UV curing, greatly improving the surface hardness, wear resistance (tested by experiment, it can resist steel wool rubbing for more than 5000-8000 times), chemical resistance and scratch resistance of the cured ink coating. The uniformly dispersed nanoparticles play a role in dispersion reinforcement, further enhancing the above properties.

[0087] The extremely high functionality is the fundamental reason for its ability to greatly improve coating hardness and wear resistance. Its low viscosity helps to balance the high viscosity brought by the specially modified dual-cured cycloaliphatic polyurethane acrylate, improving the overall rheological properties of the printed ink. The nano-hybrid technology ensures the stable dispersion of nanoparticles in the resin system, avoiding agglomeration and achieving uniform mechanical property enhancement.

[0088] Referring to Figure 1 , a product is shown that forms a paint film on a veneer after the printed ink of one embodiment (Example 3 below) is coated and dual-cured (i.e., after two curing). The wood grain effect on the surface of the product is clear, delicate, concave-convex, with strong three-dimensionality, and has a natural real wood material effect.

[0089] The present application also provides a preparation method of the printing ink. Referring to Figure 2 , a preparation process of the printing ink of an embodiment is shown, which specifically includes the following steps:

[0090] Step S110: 50wt% of solvent is taken and a photoinitiator is added. After stirring until completely dissolved, impurities are filtered out to obtain a mixture. This step aims to ensure that the photoinitiator is fully dispersed and dissolved, avoiding unevenness in the subsequent two curing processes.

[0091] Step S120: The remaining 50wt% of solvent is taken and monomers and the specially modified dual-cured cycloaliphatic polyurethane acrylate are added. The mixture is dispersed by a dispersing machine until the specially modified dual-cured cycloaliphatic polyurethane acrylate is completely dissolved to obtain a resin solution. The step-by-step addition of solvent in steps S110 and S120 helps to fully wet and dissolve the high-viscosity resin system.

[0092] Step S130: The mixture and the resin solution are mixed, and fluorosilicon-modified aliphatic polyurethane acrylate and nano-hybrid modified high-functionality acrylate are sequentially added. After stirring and mixing uniformly, fillers are added, and the stirring is continued to obtain a slurry. The sequential addition in order can ensure that each component, especially the resin component, can be uniformly mixed to form a stable resin homogeneous system.

[0093] Step S140: The slurry is ground to a fineness of ≤5μm. Preferably, a horizontal sand mill is used to grind the slurry. Strict control of the grinding fineness is the key to ensuring that the surface of the ink coating is fine, smooth and particle-free, and also affects the density and optical properties of the ink coating.

[0094] Step S150: Oxygen inhibitors and defoamers are added. After stirring uniformly at a stirring speed of 600-1000 r / min, the first component is filtered through a 300-mesh filter cloth. Shear-sensitive functional additives are added in the last step and filtered to ensure the purity and application performance of the printing ink.

[0095] The curing agent of the second component is directly mixed with the first component when the printing ink is coated. The first component and the second component are separately packaged before use to ensure the storage stability of the printing ink. Mixing before use can immediately initiate a thermal crosslinking reaction.

[0096] In one example, the above preparation method further includes pre-preparing the specially modified dual-cured cycloaliphatic polyurethane acrylate, referring to Figure 3 , a pre-preparation process of the specially modified dual-cured cycloaliphatic polyurethane acrylate is shown, and the specific steps include:

[0097] Step S210: 25-40 parts by weight of aliphatic polyurethane tetraacrylate prepolymer and 55-65 parts (preferably 60 parts) of mixed solvent of ethyl acetate and toluene with weight ratio of 1:2 are uniformly mixed.

[0098] Preferably, the viscosity of the aliphatic polyurethane tetraacrylate prepolymer is 5500-15000 cps@25℃, the solid content is 70-80%, the hydroxyl value is 20-30 mg KOH / g, and the functional group is 4. This prepolymer serves as a skeleton, and the tetra-functionality can provide higher initial crosslinking potential.

[0099] Step S220: After warming up to 50-60℃ (preferably 55℃), dicyclohexyl methane diisocyanate and dibutyl tin laurate are added within 30 minutes, and the reaction is kept for 80-100 min (preferably 90 min).

[0100] Preferably, the weight of dicyclohexyl methane diisocyanate (HMDI) is 16-20 parts, and the weight of dibutyl tin laurate is 0.15-0.25wt% of the weight of the aliphatic polyurethane tetraacrylate prepolymer.

[0101] Dicyclohexyl methane diisocyanate is a cycloaliphatic diisocyanate that provides yellowing resistance and mechanical strength. Dibutyl tin laurate serves as a catalyst for the chain extension reaction of the prepolymer.

[0102] Step S230: After the -NCO value reaches the preset value (about 0.1-0.2% of -NCO group content), the temperature is raised to 60-70℃ (preferably 65℃) and hydroxy acrylate, dibutyl tin laurate and hydroquinone are added dropwise within 2 hours.

[0103] Preferably, the weight of hydroxy acrylate is 8-12 parts, the hydroxy acrylate is a mixture of hydroxyethyl methacrylate (HEMA), trimethylolpropane diacrylate (TMP-DA) and pentaerythritol triacrylate (PETA) with weight ratio of 1:2:2, the weight of dibutyl tin laurate is 0.1-0.2wt% of the weight of the hydroxy acrylate, and the weight of hydroquinone is 0.05-0.15wt% of the weight of the hydroxy acrylate.

[0104] This step realizes grafting reaction, introducing acrylate double bonds and residual hydroxyl groups into the polymer chain. Hydroxyethyl methacrylate can provide primary hydroxyl groups and UV-curable double bonds. Trimethylolpropane diacrylate and pentaerythritol triacrylate can provide more double bonds and esterification points. Dibutyl tin laurate still serves as a catalyst, and hydroquinone serves as a polymerization inhibitor to prevent acrylate self-polymerization.

[0105] Step S240: Continue to heat to 75-85℃ (preferably 80℃) for 100-200min (preferably 115min) of stirring reaction, when the -NCO group content is monitored ≤0.1%, add triethylamine to neutralize the reaction for 25-35min (preferably 30min), and obtain a special modified dual-cured aliphatic polyurethane acrylate. At this time, the viscosity, solid content and hydroxyl value can be further adjusted to the specified range required.

[0106] The precise control of temperature, time and -NCO value during the synthesis process of step S210-step S240 is the key to obtaining the predetermined molecular structure, viscosity (35000-48000 cps@25℃), solid content (63±3%) and hydroxyl value (12-20 mg KOH / g).

[0107] The printing ink prepared above that meets the requirements of embossing of decorative panels is used in the application method and use process of decorative panel processing as follows:

[0108] The curing agent of the first component and the second component is mixed with the diluent (for example, using ethyl acetate) in a weight ratio of 95-105:8-12:25-35 (preferably 100:10:30) and filtered through, for example, 300 mesh filter cloth. Mixing the two components just before coating ensures that the thermal crosslinking reaction occurs promptly after coating. The main function of the diluent is to dilute the mixture of the two components to the appropriate viscosity to meet the parameter requirements of the actual micro-embossing coating process.

[0109] The above mixture is coated on the surface of the decorative paper by the micro-embossing coating process, dried to tack-free at 110-130℃ for 1-3min (preferably 2min) and cut to the appropriate size (for example, A4 paper size) for standby use. At this stage, the solvent evaporates, and the special resin system in the first component and the curing agent of the second component undergo thermal crosslinking reaction (i.e., this is the first curing), forming a smooth, flexible and plastic ink coating for the subsequent simultaneous embossing process.

[0110] Using a die steel plate (for example, a gradual texture die steel plate) heated to 220-260℃, hot pressing for 2-3min, the decorative paper and the board are bonded and embossed to obtain a composite board. At this time, the ink coating is precisely pressed out of clear, deep and natural texture under high temperature and high pressure due to its excellent flexibility and thermoplasticity.

[0111] The above composite board is UV cured using a medium-high pressure mercury lamp, and the UV energy is controlled at 600-800mJ / cm 2The product is obtained after standing and cooling for 24 hours. This stage is the second curing, and the double bond of the special resin system in the first component occurs free radical polymerization under the action of light energy of ultraviolet light, so as to push the crosslinking density to a higher degree, thereby obtaining the final high hardness, high wear resistance, stain resistance and other comprehensive performance. Standing and cooling can further release the stress and ensure that the mechanical properties of the cured ink coating tend to be stable.

[0112] In the double curing process, thermal curing causes the crosslinking reaction between the hydroxyl group at the end of the resin molecular chain and the isocyanate curing agent to form a three-dimensional network structure. UV light curing can further improve the crosslinking degree. After the double curing of the ink coating, the ink coating has very excellent toughness and wear resistance; in particular, the high temperature and high humidity resistance can be achieved, and the ink coating can be tested at 85°C and 85%RH for 120 hours, and the performance of the ink coating is stable and does not attenuate.

[0113] The following exemplary provides three embodiments and the test performance results of the finished products thereof to further illustrate the excellent performance of the printing ink for the embossed printing of the veneer according to the present application. The preparation method of the printing ink in each embodiment and the coating and curing process thereof when used in the veneer are described above, and will not be described hereinafter.

[0114] Example 1

[0115] In Example 1, the second component curing agent is not used. The specific formulation components of the first component are as follows:

[0116] Solvent: 23 parts, using ethyl acetate: PM: IPA = 10:5:8;

[0117] Monomer, 4 parts, using HDDA: DPHA = 3:1;

[0118] Photoinitiator, 4 parts, using TPO: 184 = 1:3;

[0119] Oxygen inhibitor, 0.1 part;

[0120] Special resin 40.5 parts;

[0121] FSP 8468, 18 parts;

[0122] CR 91093, 10 parts;

[0123] Defoamer, 0.4 parts;

[0124] Filler, 0 parts.

[0125] Example 2

[0126] First component:

[0127] Solvent, 22 parts, using ethyl acetate:PM:IPA = 10:5:7;

[0128] Monomer, 4 parts, using HDDA:DPHA = 3:1;

[0129] Photoinitiator, 4 parts;

[0130] Oxygen inhibitor, 0.1 part;

[0131] Special resin, 38 parts;

[0132] LUCURE 8696, 15 parts;

[0133] CR 91093, 8.5 parts;

[0134] Defoamer, 0.4 parts;

[0135] Filler, 8 parts.

[0136] Curing agent for the second component, 10 parts, using D-160N.

[0137] Example 3

[0138] First component (same as the first component of Example 2):

[0139] Solvent, 22 parts, using ethyl acetate:PM:IPA = 10:5:7;

[0140] Monomer, 4 parts, using HDDA:DPHA = 3:1;

[0141] Photoinitiator, 4 parts;

[0142] Oxygen inhibitor, 0.1 part;

[0143] Special resin, 38 parts;

[0144] LUCURE 8696, 15 parts;

[0145] CR 91093, 8.5 parts;

[0146] Defoamer, 0.4 parts;

[0147] Filler, 8 parts.

[0148] Curing agent for the second component, 10 parts, using D-120N.

[0149] The above-mentioned examples 1-3 and existing products were compared in appearance and tested in performance, wherein the existing products mainly included: UV matte oil coating, oily low-temperature baking paint and water-based PUD skin matte oil. Referring to Table 1, the main performance parameters and their specification test methods are shown. Referring to Table 2, the specific cases of various performance indicators of the above-mentioned examples and existing products are shown.

[0150] Table 1 Main performance parameters of decorative panel paint film and test methods

[0151]

[0152] Table 2 Comparison of various performance indicators of examples 1-3 and existing coatings for decorative panels

[0153] Item Control group Example 1 Example 2 Example 3 Product 1 Product 2 Product 3 Gloss (Gs) 12 45 15 16 28 75 18 Appearance Smooth and even, matte Smooth and even, glossy Smooth and even, matte Smooth and even, matte Smooth and even, semi-gloss Smooth and even, glossy Smooth and even, matte Hand feeling Rough, sandy Smooth and silky, skin-like Smooth and silky, skin-like Smooth and silky, skin-like Smooth and silky Smooth, slightly astringent Smooth, soft skin feeling Embossing effect Shallow texture, poor definition, partially broken Clear texture, obvious concave-convex feeling, clear level Clear texture, obvious concave-convex feeling, clear level Clear texture, obvious concave-convex feeling, clear level Shallow texture, weak concave-convex feeling, blurred level Clear texture, obvious concave-convex feeling, clear level Shallow texture, weak concave-convex feeling, blurred level Water drop angle 75° 112° 110° 112° 105° 85° 95° Scratch resistance test NG OK OK OK OK NG NG Pencil hardness (500g / f) HB 3H 3H 5H 3H 1H HB Steel wool resistance test (500g / f) 10 4800 6800 8800 5200 850 50 Anti-graffiti stain resistance test Heavy imprint residue No imprint residue No imprint residue No imprint residue Light imprint residue Obvious imprint residue Obvious imprint residue Anti-graffiti stain resistance test (after steel wool resistance test) Heavy imprint residue Obvious imprint residue Light imprint residue Light imprint residue Obvious imprint residue Heavy imprint residue Heavy imprint residue High temperature and humidity test Peeling, partial peeling Light whitening, visible to the naked eye Light whitening, visible but not obvious to the naked eye No change No change Partial whitening, bulging, partial peeling Obvious whitening, partial bulging peeling

[0154] In Table 2, the control group is that the decorative paper is directly compounded with the panel to form; product 1, product 2 and product 3 are existing coating products: UV matte oil, oily low-temperature baking paint and water-based PUD skin matte oil.

[0155] Referring to Figure 4-Figure 5 , the surface effect diagram of the paint film of the existing coating product after testing is shown. Figure 4 The wood grain effect after the existing UV matte oil stain-resistant coating is molded is that the lines are blurred, the lines are shallow, and the stereoscopic effect is poor. Figure 5 The effect of the ordinary oily low-temperature baking paint after the anti-graffiti stain-resistant test is that obvious stains are left and cannot be removed.

[0156] Referring to Figure 6 is the surface effect of the printed ink coating and curing obtained by example 3, and no obvious stain residue is seen after the anti-graffiti stain-resistant test.

[0157] Example 3 is a relatively preferred printed ink example, and after performance detection, the printed ink can achieve an adhesion of 5B, a viscosity of 3600 mPa·s, a gloss of 16Gs, a fineness of 5μm, a water drop angle of 112°, and a solid content of 76%. At the same time, the surface hardness is 5H, the steel wool wear resistance is 8800 times, the anti-graffiti has no residue, and the high temperature and high humidity test (temperature 85℃ and relative humidity 85%RH, for 120 hours) has no change. Compared with existing coatings (such as UV matte oil coating, oily low-temperature baking paint, water-based PUD skin matte oil, etc.), the embossing clarity, scratch resistance, wear resistance, stain resistance and the like are significantly superior.

[0158] The printed ink for decorative panel intaglio embossing, the preparation method and the application thereof provided by the embodiments of the present application have at least one or part of the following advantages:

[0159] (1) By resin system and curing agent are separated into two-component system and carry on secondary distribution curing, first through heat curing obtains initial crosslinking network to adapt to the stretching and mould pressing of embossing process to ensure that embossing is clear and delicate, and after UV curing, the crosslinking density is greatly improved to obtain high hardness, realizing that the ink coating has excellent flexibility, plasticity and wear resistance and stain resistance;

[0160] (2) By preparing a special modified dual-curing alicyclic polyurethane acrylate in advance, the resin system has both heat-curable hydroxyl groups and UV-curable acrylate double bonds, and the specific viscosity, hydroxyl value and functional group ensure that it can effectively react with the curing agent in the heat curing stage, and can quickly participate in the reaction in the UV curing stage;

[0161] (3) By using a fluorosilicon-modified aliphatic polyurethane acrylate with a trifunctional group, the fluorine and silicon segments with low surface energy are introduced into the ink coating system, ensuring that the ink coating has persistent skin-like smoothness and excellent resistance to graffiti and stains, and the stains can be easily removed without residue;

[0162] (4) By using a nano-hybrid modified high-functionality acrylate with high functionality, the wear resistance and surface hardness of the ink coating can be significantly enhanced, and the high functionality helps to form a highly dense crosslinking network during UV curing, combined with the dispersion reinforcement effect of nanoparticles, the ink coating can withstand 8800 times of friction resistance test, far exceeding conventional products, greatly prolonging the service life of the product;

[0163] (5) By controlling specific process parameters such as fineness, filtration, etc. in the preparation process, the density and integrity of the ink coating can be effectively ensured, avoiding defects such as pinholes, thereby ensuring the stain resistance and moisture resistance of the printed ink;

[0164] (6) The printed ink of the present application can maintain stable performance after high temperature and high humidity test (120 hours at 85℃ and 85%RH), and has excellent weather resistance and environmental adaptability.

[0165] Although some embodiments of the present general inventive concept have been shown and described, it will be apparent to those having ordinary skill in the art that changes can be made in these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined in the claims and their equivalents.

Claims

1. A method for preparing printing ink for gravure embossing on decorative panels, characterized in that, The printing ink prepared by the method comprises a first component and a second component, in parts by weight. In the first component, solvent: 20-30 parts; Monomer: 4-6 parts; Photoinitiator: 3-6 parts; Oxygen inhibition agent: 0.1-0.2 parts; Special modified dual-curing alicyclic polyurethane acrylate: 35-55 parts; Fluorosilicone modified aliphatic polyurethane acrylate: 15-25 parts; Nano-hybrid modified high-functionality acrylate: 8-16 parts. Defoamer: 0.3-1 part; Filler: 6-10 parts; In the second component, the curing agent is 5-10 parts. Before coating, the first component and the second component are mixed, and after coating, the ink coating is formed by secondary curing. The preparation method includes the following steps: Step S110: Take 50wt% of solvent and add photoinitiator, stir until completely dissolved, then filter out impurities to obtain a mixture; Step S120: Take the remaining 50wt% of solvent and add monomer and special modified dual-curing alicyclic polyurethane acrylate, disperse it in a disperser until the special modified dual-curing alicyclic polyurethane acrylate is completely dissolved to obtain a resin liquid. Step S130: Mix the mixture and the resin liquid, add fluorosilicone modified aliphatic polyurethane acrylate and nano-hybrid modified high-functionality acrylate in sequence, stir and mix evenly, add filler, and continue stirring to obtain a slurry. Step S140: Grind the slurry to a fineness ≤5μm; Step S150: Add oxygen inhibitor and defoamer, stir evenly at a stirring speed of 600-1000 r / min, and then filter to obtain the first component; wherein The preparation method further includes the pre-preparation of a specially modified dual-curing alicyclic polyurethane acrylate, the specific steps of which include: Step S210: By weight, 25-40 parts of aliphatic polyurethane tetraacrylate prepolymer and 55-65 parts of a mixed solvent of ethyl acetate and toluene are uniformly mixed, wherein the weight ratio of ethyl acetate to toluene is 1:

2. Step S220: After heating to 50-60℃, add dicyclohexylmethane diisocyanate and dibutyltin laurylate within 30 minutes, and maintain the temperature for 80-100 minutes. Step S230: After the -NCO value reaches the preset value, the temperature is raised to 60-70℃ and hydroxy acrylate, dibutyltin laurylate and hydroquinone are added dropwise over 2 hours; Step S240: Continue heating to 75-85℃ and stir for 100-120 min. When the -NCO group content is ≤0.1%, add triethylamine to neutralize and react for 25-35 min to obtain a specially modified double-cured alicyclic polyurethane acrylate.

2. The preparation method according to claim 1, characterized in that, The specially modified dual-cured alicyclic polyurethane acrylate has a viscosity of 35,000-48,000 cps@25℃, a solid content of 60%-70%, a hydroxyl value of 12-20 mg KOH / g, and 3 functional groups.

3. The preparation method according to claim 1, characterized in that, The fluorosilicone-modified aliphatic polyurethane acrylate is a trifunctional polyurethane acrylate.

4. The preparation method according to claim 1, characterized in that, The nano-hybridized modified high-functionality acrylate has a viscosity of 500-1500 cps@25℃, a solid content of 80%-90%, and 9-10 functional groups.

5. The preparation method according to any one of claims 1-4, characterized in that, The aliphatic polyurethane tetraacrylate prepolymer has a viscosity of 5500-15000 cps@25℃, a solid content of 70-80%, a hydroxyl value of 20-30 mg KOH / g, and a functional group of 4.

6. The preparation method according to claim 5, characterized in that, In step S220, by weight, The dicyclohexylmethane diisocyanate is present in quantities of 16-20 parts. The weight of the dibutyltin laurylate is 0.15-0.25 wt% of the weight of the aliphatic polyurethane tetraacrylate prepolymer.

7. The preparation method according to claim 5, characterized in that, In step S230, by weight, The hydroxy acrylate is present in quantities of 8-12 parts. The hydroxy acrylate is a mixture of hydroxyethyl methacrylate, trimethylolpropane diacrylate, and pentaerythritol triacrylate in a weight ratio of 1:2:

2. The weight of the dibutyltin lauryl ester is 0.1-0.2 wt%. The weight of the hydroquinone is 0.05-0.15 wt% of the weight of the hydroxy acrylate.

8. An application of a printing ink in gravure embossing on decorative panels, wherein the printing ink is a printing ink obtained by the preparation method according to any one of claims 1-7, characterized in that, During coating, the first component, the second component and the diluent are mixed evenly in a weight ratio of 95-105:8-12:25-35, filtered and then coated on the surface of the decorative paper. Dry at 110-130℃ for 1-3 minutes until surface dry; The dried decorative paper and the board are hot-pressed together at 220-260℃ for 2-3 minutes through a mold steel plate to complete the bonding and embossing process and obtain the composite board. The composite board is UV cured with a UV energy range of 600-800 mJ / cm². 2 Forming an ink coating.

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