A pet sandwich composite wood grain board and a preparation process thereof

Abstract

The application provides a PET sandwich composite wood grain plate and a preparation process thereof, and has a surface micro-crease structure, comprises a primer and a topcoat, and the polymerizable monomers, namely, vinyl benzimidazole and vinyl imidazole, in the topcoat have photosensitive groups, namely, benzimidazole and imidazole, can synergize with a photoinitiator, promote the generation and transmission of free radicals under the action of UV light, increase the free radical concentration, can strengthen the UV energy gradient change from the topcoat to the primer, increase the micro-crease size, promote the diffuse reflection of light on the surface layer, reduce the gloss, and improve the scratch resistance and hardness.

Description

Technical Field

[0001] This invention belongs to the field of composite board technology, and specifically relates to a process for preparing PET sandwich composite wood grain board. Background Technology

[0002] Composite panels, with their advantages of being lightweight and inexpensive, are widely used in furniture, flooring, and other home furnishing applications. Their combination of high strength, wear resistance, scratch resistance, durability, and low reflectivity is highly sought after in this field. Therefore, functional coatings are typically applied to the surface of composite panels to achieve these properties. For example, matte coatings can reduce gloss and improve the anti-reflective properties of composite panels. Common matte coatings involve adding matting agents to the base resin, such as silica matting powder, high-filler materials, micro-wax powder, and organic matting resin fillers. After being exposed to ultraviolet light, the matting agents in the coating bulge on the surface, creating an uneven surface effect that produces diffuse reflection and reduces gloss.

[0003] Chinese invention patent CN117139111A, by adding multiple LED curing sections, allows the flooring to form a relatively stable pre-cured structure before entering the excimer laser (MEC) curing section. After passing through the MEC section, short wavelengths only form a microscopic matte structure on the UV paint surface, reducing gloss. The stable pre-cured structure ensures the uniformity of the overall gloss of the flooring and avoids excessive shrinkage during the topcoat drying process, which could lead to increased floor warping. Furthermore, by using excimer laser curing, this flooring effectively increases the micro-wrinkles on the UV surface. Unlike the matte effect achieved through fillers, the surface of excimer-cured flooring is softer, and excimer laser curing can enhance the surface curing effect, making the flooring more scratch-resistant and stain-resistant. However, the UV curing process requires the use of excimer lamp UV curing equipment and must be carried out under nitrogen protection, which are relatively demanding and increase production costs, resulting in low equipment coverage and limiting the large-scale promotion of this method. Summary of the Invention

[0004] To overcome the problems existing in the prior art, the purpose of this invention is to provide a PET sandwich composite wood grain board with a surface micro-wrinkled structure, including a primer and a topcoat. The polymerizable monomers vinylbenzimidazole and vinylimidazole in the topcoat have photosensitive groups benzimidazole and imidazole, which can synergistically interact with photoinitiators to promote the generation and transmission of free radicals under UV light irradiation, increase the free radical concentration, enhance the UV energy gradient change from the topcoat to the primer, increase the size of the micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A PET sandwich composite wood grain board with a micro-wrinkled surface structure includes a primer and a topcoat. The primer comprises the following components: 10-45 parts polyether polyol, 15-45 parts isocyanate, 0.5-2 parts catalyst, 5-25 parts hydroxyl acrylate, 2-12 parts crosslinking agent, 1-5 parts photoinitiator, 3-25 parts long-chain alkyl acrylate, 6-24 parts carboxyacrylate, 1-8 parts isoborneol acrylate, and 0.1-10 parts leveling agent. The topcoat comprises the following components: 10-45 parts polyester polyol, 15-45 parts isocyanate, 0.5-2 parts catalyst, 5-25 parts hydroxyl acrylate, 2-12 parts crosslinking agent, 1-5 parts photoinitiator, 6-24 parts carboxyacrylate, 1-25 parts vinylimidazole, 1-25 parts vinylbenzimidazole, and 0.1-10 parts leveling agent.

[0007] Preferably, the isocyanate is one or more selected from isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, diphenylmethylene diisocyanate, dicyclohexylmethane diisocyanate, and phenyl 4-bromoisocyanate.

[0008] Preferably, the catalyst is one or more of dibutyltin dilaurate, stannous octoate, triethyldiamine, dimethylcyclohexylamine, and pentamethyldiethyltriamine.

[0009] Preferably, the hydroxyacrylate is one or more of hydroxyethyl acrylate or hydroxyethyl methacrylate.

[0010] Preferably, the crosslinking agent is one or more of allyl glycidyl ether, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate, and propoxylated glycerol triacrylate.

[0011] Preferably, the photoinitiator is one or more of methyl benzoylformate, photoinitiator 754, 2-hydroxy-2-methyl-1-phenylpropanone, diethoxyacetophenone, hydroxyalkyl phenyl ketone, and aminoalkyl phenyl ketone.

[0012] Preferably, the photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenylpropanone, diethoxyacetophenone, hydroxyalkylacetophenone, and aminoalkylacetophenone.

[0013] Preferably, the long-chain alkyl acrylate is one or more selected from isooctyl acrylate, lauryl acrylate, stearate acrylate, isooctyl methacrylate, lauryl methacrylate, and stearate methacrylate.

[0014] Preferably, the carboxyacrylate is one or more of maleic anhydride, phthalic anhydride, hydrogenated phthalic anhydride, and maleic anhydride.

[0015] Preferably, the preparation method of the primer includes the following steps:

[0016] S1. Mix polyether diol, isocyanate and catalyst, and react at 25-85℃ for 1-4 hours;

[0017] S2. Add hydroxy acrylate, heat to 35-90℃ and react for 1-3 hours, then cool to room temperature;

[0018] S3. Continue to add crosslinking agent, photoinitiator, long-chain alkyl acrylate, carboxyacrylate, isoborneol acrylate, and leveling agent, and stir until homogeneous to obtain the final product.

[0019] Preferably, the reaction temperature in step S1 is 45-65℃ and the reaction time is 1-2 hours.

[0020] Preferably, the reaction temperature in step S2 is 55-75℃, and the reaction time is 1-2 hours.

[0021] Preferably, in step S3, the stirring speed is 1200-2500 r / min and the stirring and dispersion time is 15-60 min.

[0022] Preferably, the preparation method of the topcoat includes the following steps:

[0023] S1. Mix polyether diol, isocyanate and catalyst, and react at 45-85℃ for 1-4 hours;

[0024] S2. Add hydroxy acrylate, heat to 55-85℃ and react for 1-3 hours, then cool to room temperature;

[0025] S3. Continue to add crosslinking agent, photoinitiator, carboxyacrylate, vinylimidazole, vinylbenzimidazole, and leveling agent, and stir until homogeneous to obtain the final product.

[0026] Preferably, the reaction temperature in step S1 is 45-65℃ and the reaction time is 1-2 hours.

[0027] Preferably, the reaction temperature in step S2 is 55-75℃, and the reaction time is 1-2 hours.

[0028] Preferably, in step S3, the stirring speed is 1200-2500 r / min and the stirring and dispersion time is 15-60 min.

[0029] A manufacturing process for a PET sandwich composite wood grain board specifically includes the following steps:

[0030] Step 1: Apply adhesive to the upper and lower surfaces of the wood substrate to form an adhesive layer, then lay the PET layer. After the layers are laid, place it in a molding machine for hot pressing, and then cool and shape it to obtain a PET sandwich wood grain board.

[0031] Step 2: Apply a primer evenly to the surface of the PET sandwich wood grain board obtained in Step 1, and pre-cur it using an LED lamp to form a coating with a thickness of 20-40μm; the wavelength of the LED lamp is selected as 320-400nm, and the curing time is 1-5min.

[0032] Step 3: Apply the topcoat evenly to the surface of the coating obtained in Step 2, and cure it with an LED lamp to form a coating with a thickness of 40-120μm, thus obtaining a PET sandwich composite wood grain board with a surface micro-wrinkle structure; the wavelength of the LED lamp is selected as 320-380nm, and the curing time is 1-10min.

[0033] Preferably, the hot-pressing temperature in step one is 100℃-250℃, and the hot-pressing pressure is 1 bar-5 bar.

[0034] Preferably, in step two, the wavelength is selected as 380-400nm and the curing time is 1-3min.

[0035] Preferably, in step three, the wavelength is selected as 320-365nm and the curing time is 2-8min.

[0036] The beneficial effects of this invention are as follows:

[0037] 1) The PET sandwich composite wood grain board of the present invention includes a primer and a topcoat. The polymerizable monomers vinylbenzimidazole and vinylimidazole in the topcoat have photosensitive groups benzimidazole and imidazole, which can promote the generation and transmission of free radicals under UV light, increase the concentration of free radicals, strengthen the UV energy gradient change from the topcoat to the primer, increase the size of micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness.

[0038] 2) The topcoat of the PET sandwich composite wood grain board of the present invention contains polymerizable monomers vinylbenzimidazole and vinylimidazole, which have photosensitive groups benzimidazole and imidazole. They can synergistically interact with photoinitiators to increase the concentration of free radicals, enhance the UV energy gradient change from topcoat to primer, increase the size of micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The present invention will be further explained below with reference to specific embodiments.

[0041] Preparation Example 1

[0042] The primer comprises the following components: 25 parts PPG-2000, 35 parts isophorone diisocyanate, 0.5 parts dibutyltin dilaurate catalyst, 8 parts hydroxyethyl acrylate, 3 parts tripropylene glycol dipropylene ester crosslinking agent, 1 part hydroxyalkyl benzophenone photoinitiator, 8 parts isooctyl acrylate, 7 parts maleic anhydride, 5 parts isoborneol acrylate, and 2 parts Tego450 leveling agent.

[0043] The preparation method of the primer includes the following steps:

[0044] S1. PPG-2000, isophorone diisocyanate and catalyst dibutyltin dilaurate are mixed and reacted at 45°C for 1 hour.

[0045] S2. Add hydroxyethyl acrylate, heat to 55°C and react for 1 hour, then cool to room temperature;

[0046] S3. Continue to add crosslinking agent tripropylene glycol dipropylene ester, photoinitiator hydroxyalkyl phenyl ketone, isooctyl acrylate, 7 parts of maleic anhydride, isoborneol acrylate and leveling agent Tego450, and stir and disperse at 2000 r / min for 30 min to obtain the primer.

[0047] The topcoat comprises the following components: 25 parts of polyester polyol XCP-2000N, 35 parts of isophorone diisocyanate, 0.5 parts of catalyst dibutyltin dilaurate, 8 parts of hydroxyethyl acrylate, 3 parts of crosslinking agent pentaerythritol triacrylate, 1 part of photoinitiator hydroxyalkyl benzophenone, 7 parts of maleic anhydride, 3 parts of vinylimidazole, 5 parts of vinylbenzimidazole, and 2 parts of leveling agent Tego450.

[0048] The preparation method of the topcoat includes the following steps:

[0049] S1. Mix polyester polyol XCP-2000N, isophorone diisocyanate and catalyst dibutyltin dilaurate, and react at 45°C for 1 hour.

[0050] S2. Add hydroxyethyl acrylate, heat to 55°C and react for 1 hour, then cool to room temperature;

[0051] S3. Continue to add the crosslinking agent pentaerythritol triacrylate, the photoinitiator hydroxyalkyl phenyl ketone, maleic anhydride, vinylimidazole, vinylbenzimidazole and leveling agent Tego450, and stir and disperse at 2000 r / min for 30 min to obtain the topcoat.

[0052] Preparation Example 2

[0053] The primer and topcoat were prepared according to the method of Preparation Example 1, with the only difference being that vinylimidazole was replaced with vinylbenzimidazole.

[0054] Preparation Example 3

[0055] The primer and topcoat were prepared according to the method of Preparation Example 1, with the only difference being that vinylbenzimidazole was replaced with vinylimidazole.

[0056] Preparation Example 4

[0057] The primer and topcoat were prepared according to the method of Preparation Example 1, with the only difference being that vinylbenzimidazole and vinylimidazole were replaced with isoborneol acrylate.

[0058] Example 1

[0059] A PET sandwich composite wood grain board with a micro-wrinkled surface structure is manufactured using the following steps:

[0060] Step 1: Apply adhesive to the upper and lower surfaces of the wood substrate to form an adhesive layer, then lay the PET layer. After the layers are laid, place it in a molding machine for hot pressing. The hot pressing temperature is 180℃ and the hot pressing pressure is 3 bar. Then cool and shape to obtain PET sandwich wood grain board.

[0061] Step 2: The primer prepared in Example 1 is uniformly coated on the surface of the PET sandwich wood grain board obtained in Step 1, and pre-cured using an LED lamp to form a coating with a thickness of 20 μm; the wavelength of the LED lamp is 400 nm, and the curing time is 1 min.

[0062] Step 3: The topcoat prepared in Preparation Example 1 is evenly applied to the surface of the coating obtained in Step 2, and cured with an LED lamp to form a coating with a thickness of 80 μm, thus obtaining a PET sandwich composite wood grain board with a surface micro-wrinkle structure; the wavelength of the LED lamp is 365 nm, and the curing time is 8 min.

[0063] Example 2

[0064] A PET sandwich composite wood grain board is prepared according to the method of Example 1, the only difference being that the primer prepared in Example 1 is replaced with the primer prepared in Example 2, and the topcoat prepared in Example 1 is replaced with the topcoat prepared in Example 2.

[0065] Example 3

[0066] A PET sandwich composite wood grain board is prepared according to the method of Example 1, the only difference being that the primer prepared in Example 1 is replaced with the primer prepared in Example 3, and the topcoat prepared in Example 1 is replaced with the topcoat prepared in Example 3.

[0067] Example 4

[0068] A PET sandwich composite wood grain board is prepared according to the method of Example 1, the only difference being that the primer prepared in Example 1 is replaced with the primer prepared in Example 4, and the topcoat prepared in Example 1 is replaced with the topcoat prepared in Example 4.

[0069] Comparative Example 1

[0070] A PET sandwich composite wood grain board is prepared according to the method of Example 1, the only difference being that step two is omitted, and in step three, the topcoat obtained in Preparation Example 1 is used to form a coating with a thickness of 100 μm.

[0071] Comparative Example 2

[0072] A PET sandwich composite wood grain board is prepared according to the method of Example 1, the only difference being that step two is omitted, and in step three, a coating with a thickness of 100 μm is formed using the primer obtained in Preparation Example 1.

[0073] Performance testing

[0074] The performance of the PET sandwich composite wood grain boards obtained in Examples 1-4 and Comparative Examples 1-2 was characterized using the following test methods:

[0075] 1) Gloss: The specular gloss under 60° geometric conditions was determined according to the test standard GB / T9754-2007.

[0076] 2) Scratch resistance: The scratch resistance performance was determined according to the test standard GB / T9279-2007.

[0077] 3) Hardness: Hardness test was conducted according to the test standard GB / T 6739-2022.

[0078] Table 1 Performance of PET Sandwich Composite Wood Grain Board

[0079]

[0080]

[0081] A comparison of Example 1, Comparative Example 1, and Comparative Example 2 shows that the PET sandwich composite wood grain board prepared in Example 1 of this invention has lower gloss, higher hardness, and better scratch resistance. This may be because the PET sandwich composite wood grain board in Example 1 includes a primer and a topcoat. The PUA obtained by prepolymerization in the topcoat and primer can polymerize with polymerizable monomers and crosslinking agents under the action of photoinitiator hydroxyalkyl benzophenone and UV light. Due to the oxygen inhibition effect, the surface layer completes curing first, forming a hard surface layer. The internal stress generated by the volume reduction during the curing of the lower coating is transmitted to the surface layer, causing micro-folds. Wrinkles are formed by the gradual decrease of UV energy from top to bottom, creating an energy gradient. The polymerizable monomers vinylbenzimidazole and vinylimidazole in the topcoat have photosensitive groups benzimidazole and imidazole, which can promote the generation and transmission of free radicals under UV light, increasing the concentration of free radicals. On the one hand, this can strengthen the change of UV energy gradient from topcoat to primer, increase the size of micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness. On the other hand, it can also promote the further full reaction of prepolymerized PUA and polymerizable monomers and crosslinking agents, improve the density of the three-dimensional network crosslinking structure, and improve scratch resistance and hardness.

[0082] A comparison of Examples 1, 2, and 3 shows that the PET sandwich composite wood grain board prepared in Example 1 of this invention has lower gloss, higher hardness, and better scratch resistance. This may be because the polymerizable monomers vinylbenzimidazole and vinylimidazole in the topcoat of the PET sandwich composite wood grain board in Example 1 have photosensitive groups benzimidazole and imidazole, which can synergistically interact with the photoinitiator to increase the concentration of free radicals, enhance the UV energy gradient change from the topcoat to the primer, increase the size of micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness.

[0083] A comparison of Examples 1, 2, 3, and 4 shows that the PET sandwich composite wood grain board prepared in Example 1 of this invention has lower gloss, higher hardness, and better scratch resistance. This may be because, compared with the norborneol group, the photosensitive groups benzimidazole and imidazole can synergistically interact with the photoinitiator, increase the concentration of free radicals, strengthen the UV energy gradient change from the topcoat to the primer, increase the size of micro-wrinkles, promote diffuse reflection of light on the surface, reduce gloss, and improve scratch resistance and hardness.

[0084] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A PET sandwiched composite wood grain board, characterized by, The surface micro-crease structure has a primer and a topcoat, the primer comprises the following components: polyether polyol 10-45 parts, isocyanate 15-45 parts, catalyst 0.5-2 parts, hydroxy acrylate 5-25 parts, crosslinking agent 2-12 parts, photoinitiator 1-5 parts, long-chain alkyl acrylate 3-25 parts, carboxyl acrylate 6-24 parts, isobornyl acrylate 1-8 parts, leveling agent 0.1-10 parts; the topcoat comprises the following components: polyester polyol 10-45 parts, isocyanate 15-45 parts, catalyst 0.5-2 parts, hydroxy acrylate 5-25 parts, crosslinking agent 2-12 parts, photoinitiator 1-5 parts, carboxyl acrylate 6-24 parts, vinyl imidazole 1-25 parts, vinyl benzimidazole 1-25 parts, leveling agent 0.1-10 parts.

2. The PET sandwich composite wood grain board according to claim 1, characterized in that, The preparation method of the primer comprises the following steps: S1, mixing polyether polyol, isocyanate and catalyst, and reacting at 25-85℃ for 1-4h; S2, adding hydroxy acrylate, warming to 35-90℃ for 1-3h, and cooling to room temperature; S3, continuously adding crosslinking agent, photoinitiator, long-chain alkyl acrylate, carboxyl acrylate, isobornyl acrylate and leveling agent, and stirring uniformly.

3. The PET sandwich composite wood veneer panel according to claim 1, characterized in that, The preparation method of the topcoat comprises the following steps: S1, mixing polyester polyol, isocyanate and catalyst, and reacting at 45-85℃ for 1-4h; S2, adding hydroxy acrylate, warming to 55-85℃ for 1-3h, and cooling to room temperature; S3, continuously adding crosslinking agent, photoinitiator, carboxyl acrylate, vinyl imidazole, vinyl benzimidazole and leveling agent, and stirring uniformly.

4. The PET sandwich composite wood veneer panel according to claim 1, characterized in that, The isocyanate is one or more of isophorone diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, diphenylmethylene diisocyanate, diisocyanate dicyclohexylmethane and 4-bromophenyl isocyanate.

5. The PET sandwiched composite wood grain board according to claim 1, characterized in that, The crosslinking agent is one or more of allyl glycidyl ether, 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated trimethylolpropane triacrylate and propoxylated glycerol triacrylate.

6. The PET sandwich composite wood veneer panel according to claim 1, wherein, The photoinitiator is one or more of methyl benzoylformate, photoinitiator 754, 2-hydroxy-2-methyl-1-phenylpropanone, diethoxyphenylacetophenone, hydroxyalkyl phenone and amine alkyl phenone.

7. The PET sandwich composite wood veneer panel according to claim 1, wherein, The photoinitiator is one or more of 2-hydroxy-2-methyl-1-phenylpropanone, diethoxyphenylacetophenone, hydroxyalkyl phenone and amine alkyl phenone.

8. A preparation process of the PET sandwich composite wood grain board according to any one of claims 1-7, comprising the following reaction steps: Step one, coating adhesive on the upper and lower surfaces of the wood substrate to form an adhesive layer and then laying the PET layer, after the laying is completed, putting into a mold pressing machine for hot pressing, then cooling and shaping to obtain the PET sandwich wood grain board; Step two, evenly coat the primer on the upper surface of the PET sandwich wood grain board obtained in step one, and pre-cure using LED lamp to form a coating with a thickness of 20-40 μm; the wavelength of the LED lamp is selected to be 320-400 nm, and the curing time is 1-5 min; Step three, evenly coat the topcoat on the upper surface of the coating obtained in step two, and cure using LED lamp to form a coating with a thickness of 40-120 μm, thereby obtaining the PET sandwich composite wood grain board with a surface micro-crease structure; the wavelength of the LED lamp is selected to be 320-380 nm, and the curing time is 1-10 min.

9. The process for preparing a PET sandwich composite wood veneer panel according to claim 8, characterized in that, In the step two, the wavelength is selected to be 380-400 nm, and the curing time is 1-3 min; in the step three, the wavelength is selected to be 320-365 nm, and the curing time is 2-8 min.

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