A weather-resistant rigid PVC fence printing board and its preparation method

Abstract

This invention relates to a weather-resistant rigid PVC fence printing board, belonging to the field of wood-plastic fence technology. The weather-resistant rigid PVC fence printing board includes a substrate layer, a digitally printed pattern layer disposed on the substrate layer, and a wear-resistant layer covering the digitally printed pattern layer; the wear-resistant layer contains a light stabilizer. This invention, by using a printed pattern layer to replace the roller-engraved pattern on the rigid co-extruded surface, adjusts the light stabilizer originally added to the rigid co-extruded surface layer to the wear-resistant layer covering the printed pattern layer. This not only solves the problem of decreased mechanical properties of PVC boards due to the use of light stabilizers, but also further improves the effect of the light stabilizer. For light stabilizers, the wear-resistant layer has several advantages over the rigid co-extruded surface layer.

Description

Technical Field

[0001] This invention relates to a weather-resistant rigid PVC fence printing board, belonging to the field of wood-plastic fence technology. Background Technology

[0002] Wood-plastic composite (WPC) fences are commonly used for partitions in home courtyards and other locations. Compared to wooden fences, they are more resistant to corrosion, and compared to metal fences, they are lighter and cheaper, and they do not rust. Therefore, WPC fences dominate the market. Among the plastics used, PVC is the most popular material for WPC fences due to its high cost-effectiveness.

[0003] However, PVC resin is a material that is prone to aging. As a fence panel, it is exposed to the outdoors for a long time, facing wind, sun, and rain. After a few years of use, it will show serious signs of aging and may even pose safety hazards. Therefore, people often add some UV stabilizers, antioxidants, and other additives to the surface material of the panel to slow down the aging process.

[0004] For example, patent application CN 108676296A discloses a composite fence profile composed of a core layer and a skin layer, with a weight ratio of (90-97):(3-10). The core layer is made from the following raw materials: PVC resin, filler A, processing aids, low-temperature impact modifier, weather-resistant modifier, antioxidant or UV-resistant modifier, calcium-zinc stabilizer, and lubricant. The skin layer is made from the following raw materials: PVC resin, filler B, processing aids, low-temperature impact modifier, weather-resistant modifier, antioxidant or UV-resistant modifier, calcium-zinc stabilizer, lubricant, and pigment. However, because the surface material is relatively thick, a large amount needs to be added to achieve a certain effect, and the addition of these additives can also have some negative effects on the mechanical properties of the board, such as affecting the compressive strength and modulus of elasticity. Summary of the Invention

[0005] The present invention aims to solve the above problems and provides a method for preparing weather-resistant rigid PVC fence printing material.

[0006] The PVC fence panel of the present invention does not use weather-resistant additives in the surface layer, so it does not affect the mechanical properties of the panel; and by adding weather-resistant additives to the UV varnish coating, better weather resistance can be achieved with less weather-resistant additives.

[0007] The technical solution of the present invention to solve the above problems is as follows:

[0008] A weather-resistant rigid PVC fence printing board includes a substrate layer, a digitally printed pattern layer disposed on the substrate layer, and a wear-resistant layer covering the digitally printed pattern layer; the wear-resistant layer contains a light stabilizer.

[0009] As a preferred embodiment of the above technical solution, the substrate layer includes a PVC foam core layer and a rigid surface layer covering the PVC foam core layer; the rigid surface layer does not contain a light stabilizer.

[0010] Light stabilizers have a certain plasticizing effect, which can affect the mechanical properties of the board after use. Therefore, in the above-mentioned technical solution of the present invention, while the wear-resistant layer contains a light stabilizer, the hard surface layer does not contain a light stabilizer.

[0011] As a preferred embodiment of the above technical solution, the wear-resistant layer is formed by UV varnish after UV curing, wherein the UV varnish comprises: acrylate monomers / oligomers, reactive diluents, photoinitiators, and light stabilizers.

[0012] As a preferred embodiment of the above technical solution, the photoinitiator and the light stabilizer have different ultraviolet absorption bands; the light stabilizer has absorption in the 280-380nm band; the photoinitiator has absorption in the 380-400nm band, or absorption in the visible light region.

[0013] Ultraviolet absorbers are light stabilizers that absorb the ultraviolet portion of a light source without undergoing any change themselves. Photoinitiators, on the other hand, are compounds that absorb energy of a specific wavelength and generate free radicals, cations, etc., thereby initiating monomer polymerization, cross-linking, and curing; they are also known as photosensitizers or photocuring agents. Specifically, in this invention, the inventors aim to selectively trigger the photoinitiator during preparation without causing absorption by the light stabilizer; while during use, the light stabilizer can absorb ultraviolet radiation from sunlight. Therefore, the photoinitiator and light stabilizer should have different absorption bands, and the photoinitiator should have a lower absorption threshold than the light stabilizer, i.e., the photoinitiator should have a longer absorption band. In this invention, the light stabilizer absorbs in the 280–380 nm band; the photoinitiator absorbs in the 380–400 nm band, or absorbs in the visible light region.

[0014] As a preferred embodiment of the above technical solution, the photoinitiator is selected from one or more of TPO, TEPO, and BAPO. These initiators have absorption in the wavelength range above 390nm, so they can be irradiated with mercury lamps above 390nm. This can effectively avoid the loss of irradiation energy due to absorption by the light stabilizer and minimize the degradation of the substrate caused by irradiation.

[0015] Under ultraviolet (UV) light, polymers undergo covalent bond breakage, forming oxygen free radicals that degrade the polymer, leading to poor appearance and mechanical properties. Adding a light stabilizer selectively absorbs this high-energy UV light, thus delaying polymer degradation. In the above-mentioned technical solution of this invention, the light stabilizer includes UV absorbers and hindered amine light stabilizers. Different types of polymers exhibit different UV wavelengths that cause degradation. PVC degrades more readily than polyolefins; the C-Cl bond has a lower bond energy and a longer bond length than CH and CC bonds, thus it is reasonable to assume that the C-Cl bond breaks more easily. In fact, PVC degrades over a wide range of wavelengths, especially in the higher-energy bands of sunlight, such as 280–380 nm.

[0016] Different UV absorbers can absorb UV rays of different wavelengths. A UV absorber should meet the following conditions: strong absorption of UV rays; good thermal stability and low volatility; good chemical stability and no reaction with material components; good compatibility and uniform dispersion in the material; good light stability and no decomposition under sunlight; colorless, non-toxic, and odorless; and washable.

[0017] 2,4-Dihydroxybenzophenone is a UV absorber, appearing as pale needle-like crystals or a white powder with a melting point of 136–149°C. It is soluble in solvents such as acetone, methanol, ethanol, and ethyl acetate, but extremely insoluble in water. Its absorption wavelength range is 280–340 nm. It is suitable for use on polyvinyl chloride (PVC), typically at a dosage of 0.1%–1%. However, its disadvantage is its generally poor photostability.

[0018] 2-Hydroxy-4-methoxybenzophenone is a UV absorber, a light yellow or white crystalline powder. It has a melting point of 62–66°C. It is soluble in solvents such as acetone, methanol, ethanol, and ethyl acetate, but extremely sparingly soluble in water. Its absorption wavelength range is 28–340 nm. It is suitable for use on polyvinyl chloride (PVC), typically at a dosage of 0.1%–1.5%.

[0019] 2-Hydroxy-4-n-Octyloxybenzophenone is a light yellow or white crystalline powder, used as a UV absorber. It has a melting point of 48–49°C. It is soluble in acetone, benzene, ethanol, isopropanol, and other solvents; slightly soluble in dichloroethane; and insoluble in water. It strongly absorbs ultraviolet light with wavelengths of 270–330 nm and is suitable for use in polyvinyl chloride (PVC), typically at a dosage of 0.1%–1%.

[0020] 2-(2'-Hydroxy-3',5'-Di-tert-phenyl)-5-chlorobenzotriazole is a light yellow ultraviolet absorber that strongly absorbs ultraviolet light with wavelengths of 270–380 nm. It exhibits good chemical stability and extremely low volatility. It can be used in polyvinyl chloride (PVC). The typical dosage in plastics is 1%–3%.

[0021] Resorcinol monobenzoate is a white crystalline powder, a UV absorber. It has a melting point of 132–135°C, is soluble in acetone and ethanol, and slightly soluble in benzene, water, and n-heptane. It absorbs very little UV light in the 300–400 nm wavelength range, but undergoes molecular rearrangement under light to form 2,4-dihydroxybenzophenone, thus exerting a photostabilizing effect. It is suitable for use on polyvinyl chloride (PVC), typically at a dosage of 1%–2%.

[0022] 4-Benzoyloxy-2,2,6,6-Tetramethylpiperidine, a hindered amine light stabilizer, has almost no ability to absorb ultraviolet light itself, but it can effectively capture the active free radicals generated by polymers under ultraviolet light, thus exerting a light-stabilizing effect. It is a white crystalline powder with a melting point of 95–98℃ and a decomposition temperature above 280℃. It is soluble in acetone, ethanol, ethyl acetate, and toluene, but insoluble in water. It exhibits excellent synergistic effects when used in combination with antioxidants and ultraviolet absorbers.

[0023] As a preferred embodiment of the above technical solution, the light stabilizer includes ultraviolet absorbers and hindered light stabilizers.

[0024] As a further preferred embodiment of the above technical solution, the mass ratio of the ultraviolet absorber to the hindered light stabilizer is ultraviolet absorber: hindered light stabilizer = 1:(0.5~0.8).

[0025] As a further preferred embodiment of the above technical solution, the ultraviolet absorber is selected from at least two of benzophenones, benzotriazoles, oxaloaniline, and triazines; more specifically, the ultraviolet absorber includes benzophenones and benzotriazoles; the benzophenones include 2-hydroxy-4-methoxybenzophenone and 2-hydroxy-4-n-octyloxybenzophenone; the benzotriazoles include 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole. Furthermore, since resorcinol monobenzoate undergoes molecular rearrangement under light to generate 2-hydroxy-4-methoxybenzophenone, resorcinol monobenzoate can be considered as 2-hydroxy-4-methoxybenzophenone among the options for the above ultraviolet absorber.

[0026] As a preferred embodiment of the above technical solution, a primer layer and a color paint layer attached to the primer layer are further provided between the substrate and the pattern layer, wherein the color paint layer is white paint.

[0027] As a preferred embodiment of the above technical solution, the primer layer is a light-cured epoxy acrylate varnish.

[0028] As a preferred embodiment of the above technical solution, the paint layer is a light-cured epoxy acrylate paint with added titanium dioxide.

[0029] As a preferred embodiment of the above technical solution, the digitally printed pattern layer is formed by an industrial printer.

[0030] In the above technical solution of the present invention, the ink used in the industrial printer is UV ink or EB ink, and contains at least three different colors of ink.

[0031] Another object of the present invention is to provide a method for preparing the above-mentioned sheet material.

[0032] A method for preparing a weather-resistant rigid PVC fence printing board includes the following steps:

[0033] S1. Provide a substrate board as the substrate layer for fence printing materials;

[0034] S2. The substrate board is subjected to belt sanding and corona treatment in sequence;

[0035] S3. Apply a primer to the surface of the substrate board that has been treated by roller coating, and then perform a light curing treatment to produce a primer layer;

[0036] S4. Roller-coating a white paint with hiding power onto the primer layer, and then perform a light curing treatment to produce a paint layer.

[0037] S5. Print on the paint layer using an industrial printer, and then perform a light curing process to produce a digitally printed pattern layer.

[0038] S6. Spray UV varnish onto the digitally printed pattern layer, and then perform UV curing treatment; the UV varnish contains: acrylate monomers / oligomers, reactive diluents, photoinitiators, and light stabilizers.

[0039] In the above-described technical solution of this invention, roller coating is more economical and applicable than spray coating. Roller coating production lines have lower costs, while spray coating does not refer to conventional spraying, but rather to the uniform arrangement of a large number of printheads within a very small area, such as a spray resolution of 150 DPI (i.e., 150 printheads evenly distributed within a 1 square inch area). Before printing the pattern, using a conventional roller coating line not only provides a good coating effect but also has low equipment costs, low maintenance costs, and convenient maintenance operations; however, after printing, to ensure that the pattern layer is not affected, a spray coating line is required, typically with a spray resolution set between 50 and 300 DPI.

[0040] As a preferred embodiment of the above technical solution, in step S3, the roller coating amount of the primer is 8-10 g / m^2; in step S4, the roller coating amount of the color paint is 15-25 g / m^2; in step S5, the spray coating amount of the printing color paste is 5-15 g / m^2; and in step S6, the spray coating amount of the UV varnish is 100-300 g / m^2.

[0041] In summary, the present invention has the following beneficial effects:

[0042] 1. This invention, by replacing the roller-engraved pattern on the rigid co-extruded surface layer with a printed pattern layer, adjusts the light stabilizer originally added to the rigid co-extruded surface layer to the wear-resistant layer covering the printed pattern layer. This not only solves the problem of decreased mechanical properties of PVC sheets due to the use of light stabilizers, but also further improves the effect of the light stabilizer. The wear-resistant layer has the following advantages over the rigid co-extruded surface layer for light stabilizers: 1) Thinner thickness: The wear-resistant layer is typically in the micrometer range, while the co-extruded surface layer is in the millimeter range. This allows for a denser distribution of the light stabilizer within the same area, thus improving the absorption of ultraviolet rays; 2) Higher transparency: The wear-resistant layer is colorless and transparent, while the co-extruded surface layer is typically gray, which undoubtedly improves the absorption of ultraviolet rays by the light stabilizer; 3) Uniform distribution: The light stabilizer is almost ideally distributed in the UV varnish, which is difficult to achieve in the raw materials of the co-extruded surface layer, further improving the absorption of ultraviolet rays by the light stabilizer.

[0043] 2. This invention optimizes the process by replacing roller engraving with a pattern layer printed on the surface of the wood-plastic fence panel. This not only simplifies the process steps but also reduces energy consumption.

[0044] 3. This invention replaces roller engraving with printed pattern layers. The printed patterns can be combined into a whole pattern, which can present a better visual effect compared to the repeating units formed by roller engraving.

[0045] 4. The present invention also first applies a primer and a white paint to the substrate layer to further improve the adhesion of the pattern layer, and the paint can eliminate color differences between different batches. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the structure of the present invention;

[0047] In the diagram, 01-substrate layer, 02-primer layer, 03-color paint layer, 04-printed pattern layer, 05-wear-resistant layer;

[0048] 01-1-PVC foam core layer; 01-2-rigid surface layer. Detailed Implementation

[0049] The present invention will be further explained and described below with reference to the accompanying drawings.

[0050] The following detailed embodiments are merely explanations of the present invention and are not intended to limit the present invention. Any changes made by those skilled in the art after reading the specification of the present invention, as long as they are within the scope of the claims, will be protected by patent law.

[0051] Example 1

[0052] A weather-resistant rigid PVC fence printing board includes a substrate layer 01. A primer layer 02, a color paint layer 03, a printing pattern layer 04, and a wear-resistant layer 05 are sequentially disposed on the substrate layer. The substrate layer 01 includes a PVC foam core layer 01-1 and a rigid surface layer 01-2 covering the PVC foam core layer 01-1.

[0053] In this embodiment, the thickness of the PVC foam core layer 01-1 was approximately 3 cm, with an average density of 0.8 g / cm³. The thickness of the rigid surface layer 01-2 was approximately 0.3 cm, and its material was PVC. This PVC was made from the same raw material as the PVC foam core layer 01-1; the only difference was that no foaming agent was added to the raw material of the rigid surface layer 01-2 during the production process, or only a very small amount of foaming agent was added. PVC raw materials and PVC foaming materials are conventional technologies in this field and will not be described in detail further.

[0054] The preparation method of the above-mentioned weather-resistant rigid PVC fence printing material is as follows:

[0055] S1. Provide the substrate layer 01 of the substrate board as described above as the fence printing board;

[0056] S2. The substrate board is subjected to belt sanding and corona treatment in sequence;

[0057] S3. Apply a primer by roller coating on the surface of the substrate board that has been treated, and then perform UV curing to produce primer layer 02. The primer formulation is as follows: 90% epoxy acrylate, 5% photoinitiator TPO, 5% diluent hydroxyethyl acrylate; roller coating amount 10g / m^2; after curing by UV lamp at 400nm and 12W / cm^2, primer layer 02 is obtained.

[0058] S4. A white paint with hiding power is rolled onto the primer layer 02, and then UV-cured to produce the paint layer 03. The primer formulation is as follows: 45% epoxy acrylate, 5% photoinitiator 819, 5% hydroxyethyl acrylate diluent, 30% nano-sized titanium dioxide, and 15% hydroxyethyl acrylate; the roll coating amount is 16 g / m^2; after curing with a 400 nm, 12 W / cm^2 UV lamp, the paint layer 03 is obtained.

[0059] S5. Print on the paint layer 03 using an industrial printer. The amount of UV ink sprayed is about 10g / m^2. Then, irradiate and cure it with a UV lamp that is compatible with the initiator contained in the ink to produce a digital printed pattern layer 04. Since the ink is provided by a third-party company, it involves its trade secrets and should not be disclosed. However, this does not pose a technical obstacle to those skilled in the art. Generally speaking, in order to avoid degradation of the substrate, a photoinitiator that absorbs in the long ultraviolet band or in the visible light region can be used, such as photoinitiator 819 or photoinitiator TPO. In this way, a 400nm UV lamp with 12W / cm^2 can be used for irradiation and curing.

[0060] S6. Spray UV varnish onto the digitally printed pattern layer 04, with a spraying amount of 200g / m^2, and then perform UV curing treatment; the UV varnish contains: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 0.5% 2-hydroxy-4-methoxybenzophenone, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0061] Example 2

[0062] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator 819, 0.5% 2-hydroxy-4-methoxybenzophenone, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0063] Example 3

[0064] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 2.0% photoinitiator 819, 2.5% photoinitiator TPO, 0.5% 2-hydroxy-4-methoxybenzophenone, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0065] Example 4

[0066] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0067] Example 5

[0068] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 1.0% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0069] Example 6

[0070] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 1.0% 2-hydroxy-4-methoxybenzophenone, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0071] Example 7

[0072] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 1.0% hydroxy-4-n-octyloxybenzophenone, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

[0073] Example 8

[0074] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, and 1.5% 2-hydroxy-4-methoxybenzophenone.

[0075] Example 9

[0076] The only difference from Example 1 is that the UV varnish formulation in step S6 is different, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, and 1.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole.

[0077] Example 10

[0078] The only difference from Example 1 is that the UV varnish formulation is different in step S6, specifically: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, and 1.5% hydroxy-4-n-octyloxybenzophenone.

[0079] Comparative Example 1

[0080] The only difference from Example 1 is that:

[0081] 1) The rigid surface layer 01-2 contains light stabilizers, and the amount of light stabilizers used is 1.5% of the PVC raw material of the rigid surface layer. The light stabilizers include: 0.5% 2-hydroxy-4-methoxybenzophenone, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine;

[0082] 2) The wear-resistant layer 05 does not contain light stabilizers. The UV varnish contains: 90.5% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, and 4.5% photoinitiator TPO.

[0083] Accelerated aging tests were conducted on Examples 1 to 10 and Comparative Example 1 according to ASTM G154-16-7, and the results are shown in the table below.

[0084]

Claims

1. A weather-resistant rigid PVC fence printing board, comprising a substrate layer (01), a digitally printed pattern layer (04) disposed on the substrate layer, and a wear-resistant layer (05) covering the digitally printed pattern layer; characterized in that: The substrate layer (01) includes a PVC foam core layer (01-1) and a rigid surface layer (01-2) covering the PVC foam core layer (01-1); the rigid surface layer (01-2) does not contain a light stabilizer. The wear-resistant layer (05) is formed by UV varnish after UV curing. The UV varnish contains: 89% polyurethane acrylate monomer / oligomer, 5% hydroxyethyl acrylate, 4.5% photoinitiator TPO, 0.5% 2-hydroxy-4-methoxybenzophenone, 0.5% 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole, and 0.5% 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

2. The weather-resistant rigid PVC fence printing board according to claim 1, characterized in that: A primer layer (02) and a color paint layer (03) attached to the primer layer (02) are provided between the substrate layer (01) and the pattern layer (04), wherein the color paint layer (03) is white paint.

3. The weather-resistant rigid PVC fence printing board according to claim 2, characterized in that: The primer layer (02) is a light-cured epoxy acrylate varnish.

4. The weather-resistant rigid PVC fence printing board according to claim 2, characterized in that: The paint layer (03) is a light-cured epoxy acrylate paint with added titanium dioxide.

5. The weather-resistant rigid PVC fence printing board according to claim 1, characterized in that: The digitally printed pattern layer (04) is formed by printing with an industrial printer.

6. A method for preparing a weather-resistant rigid PVC fence printing board according to any one of claims 1 to 5, comprising the following steps: S1. Provide a substrate board as the substrate layer (01) for the fence printing board; S2. The substrate board is sequentially subjected to belt sanding and corona treatment. S3. Apply primer to the surface of the substrate board that has been treated by roller, and then perform light curing treatment to produce primer layer (02); S4. Roller-coating a white paint with hiding power onto the primer layer (02), and then perform light curing treatment to produce a paint layer (03); S5. Print on the paint layer (03) using an industrial printer, and then perform light curing to produce a digital print pattern layer (04). S6. Spray UV varnish onto the digitally printed pattern layer (04) and then perform a UV curing process.

7. The method for preparing a weather-resistant rigid PVC fence printing board according to claim 6, characterized in that: In step S3, the roller coating amount of the primer is 8~10g / m². 2 In step S4, the roller coating amount of the paint is 15~25g / m². 2 In step S5, the amount of ink sprayed during printing is 5~15g / m². 2 In step S6, the amount of UV varnish applied is 100~300g / m². 2 .

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