A polypropylene edge-sealing tape with a photocurable functional layer and its preparation method

Abstract

This application discloses a polypropylene edge banding tape with a photocurable functional layer and its preparation method, belonging to the field of polymer material processing. The method involves reactive extrusion melt grafting of polypropylene with glycidyl methacrylate, a peroxide initiator, and comonomers. After extrusion molding, the tape undergoes corona treatment, is coated with a transparent photocurable coating containing polyurethane acrylate and nanofillers, and then cured via gradient curing and heat treatment. A black colorant is also added during the reactive extrusion melt grafting process, which is uniformly dispersed in the polypropylene matrix. Wood grain printing is applied to the black substrate, and the transparent cross-linked functional layer is chemically bonded to the wood grain layer. The resulting edge banding tape has a dyn value ≥44 dyn / cm, adhesion grade 0, and hardness of 3H-5H, exhibiting excellent adhesion, scratch resistance, environmental safety, and a black wood grain decorative effect.

Description

Technical Field

[0001] This application belongs to the field of polymer material processing technology, specifically relating to a polypropylene edge banding tape with a photocurable functional layer and its preparation method. Background Technology

[0002] Edge banding is an indispensable functional material in panel furniture manufacturing. It is used to cover the edges of engineered wood products such as particleboard and medium-density fiberboard, serving multiple functions including sealing against moisture, inhibiting formaldehyde release, and enhancing aesthetics. Currently, the mainstream edge banding materials on the market include three main categories: polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), and polypropylene (PP). Among these, polypropylene edge banding has gained increasing attention in the furniture industry in recent years due to its environmental advantages, such as being halogen-free, not producing dioxins or other toxic gases when burned, and being recyclable. In terms of decorative styles, colored and patterned edge banding is increasingly in demand in modern styles and high-end custom furniture.

[0003] However, polypropylene itself has inherent defects that limit its application in the field of high-end edge banding. First, polypropylene is a non-polar polymer material with low surface energy, resulting in poor adhesion to adhesives and wood substrates. In actual use, edge banding is prone to quality problems such as delamination, curling, and even peeling. Especially in high-temperature and high-humidity environments such as kitchens and bathrooms, the bonding strength of the edge banding decreases more significantly, severely shortening the lifespan of furniture. Second, polypropylene itself has low surface hardness and insufficient scratch resistance. Edge banding is easily scratched by hard objects in daily use, and the scratches may become channels for moisture and contaminants to penetrate.

[0004] To address the issues of low surface energy and poor adhesion in polypropylene edge banding tapes, various improvement schemes have been proposed in existing technologies. Surface roughening treatments such as sanding and chemical etching can improve the physical interlocking ability of the polypropylene surface, but they easily damage the polypropylene substrate itself and affect the aesthetics of the decorative surface, and the treatment effect is not durable. Chemical modification methods, such as chlorination and solution grafting, can introduce polar groups onto the polypropylene molecular chain, but the process is complex, costly, and may alter the bulk mechanical properties of polypropylene. Chinese patent application CN121537889A proposes a self-healing edge banding tape containing polypropylene-g-MAH modified microcapsules, but its process involves cumbersome steps such as microcapsule synthesis and freeze-drying, resulting in a long production cycle, low efficiency, and the microcapsules are prone to rupture and failure during extrusion processing.

[0005] On the other hand, ultraviolet (UV) curing coating technology has been widely used in the field of plastic surface hardening treatment due to its advantages such as fast curing speed, no solvent evaporation, and excellent coating performance. However, when UV curing coatings are directly applied to the surface of unmodified polypropylene substrates, the non-polar nature of polypropylene results in a lack of effective chemical bonding between the coating and the substrate, relying only on physical adsorption and mechanical interlocking, leading to poor coating adhesion. For colored patterned edge banding tapes, once the transparent protective layer peels off or flakes, it not only loses its protective function, but the edges of the peeled coating also create obvious visual defects on the colored base surface due to light refraction.

[0006] Furthermore, with increasing consumer awareness of environmental protection and stricter regulations in the furniture export market, edge banding tapes, in addition to meeting mechanical and decorative performance requirements, must also meet environmental safety requirements. They must not contain excessive levels of heavy metals such as cadmium, lead, mercury, hexavalent chromium, polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), and phthalates (DBP, BBP, DEHP, DIBP). Traditional PVC edge banding tapes face significant challenges in terms of environmental safety due to the presence of chlorine and phthalate plasticizers. While polypropylene edge banding tapes have environmental advantages at the base resin level, the functional additives in the formula, such as heavy metal pigments and flame retardants in the color masterbatch, may still introduce the risk of excessive levels of harmful substances. Therefore, systematic formula design and process control are necessary to ensure the environmental safety of the products.

[0007] Therefore, there is an urgent need to develop a method for preparing black polypropylene edge banding that is simple to process, reliable in performance, and environmentally friendly and safe. This method would maintain the environmental advantages of polypropylene materials while possessing excellent surface adhesion, scratch resistance, and weather resistance, thus meeting the furniture industry's pressing need for high-quality, environmentally friendly edge banding. Summary of the Invention

[0008] To address the aforementioned technical problems, this application provides a polypropylene edge banding tape with a photocurable functional layer and its preparation method. This method introduces reactive epoxy groups onto the polypropylene molecular chain using melt grafting technology, combined with online corona activation and gradient ultraviolet curing processes, to construct a transparent cross-linked functional layer that is chemically bonded to the substrate. The resulting product exhibits excellent surface properties and environmental safety. Furthermore, this application allows for the addition of a black colorant to impart a black base color to the polypropylene substrate, followed by printing a wood grain pattern on the surface of the polypropylene substrate, resulting in an edge banding tape with a sophisticated black wood grain decorative effect.

[0009] In a first aspect, this application provides a method for preparing a polypropylene edge-sealing tape with a photocurable functional layer, comprising the following steps: (1) Melt grafting Polypropylene resin, glycidyl methacrylate, peroxide initiator, and comonomer are mixed in a certain proportion and reacted and extruded at 170-230℃ to introduce reactive epoxy groups into the polypropylene molecular chain, thus obtaining glycidyl methacrylate grafted polypropylene granules. (2) Extrusion molding The glycidyl methacrylate-grafted polypropylene granules obtained in step (1) are extruded through a sheet die to obtain the edge sealing tape substrate. (3) Corona treatment At least one surface of the edge banding substrate is subjected to online corona treatment to obtain a surface-activated edge banding substrate; (4) Apply UV-curable coating A UV-curable coating composition is applied to the surface of a corona-treated edge banding substrate to form a wet coating. (5) Gradient UV curing The coated edge banding is subjected to multi-stage gradient ultraviolet light irradiation to cure the wet coating and form a transparent cross-linked functional layer. (6) Heat treatment The edge sealing tape cured by ultraviolet light is heat-treated at 70-90℃ to obtain the polypropylene edge sealing tape with the light-cured functional layer.

[0010] Furthermore, in step (1), based on the mass of the polypropylene resin, the amount of glycidyl methacrylate used is 0.5-5% of the mass of the polypropylene resin; preferably, the amount of glycidyl methacrylate used is 1-3% of the mass of the polypropylene resin.

[0011] Furthermore, in step (1), the peroxide initiator is selected from at least one of dicumyl peroxide, benzoyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; The amount of the peroxide initiator is 0.05-0.5% of the mass of the polypropylene resin; preferably, the amount of the peroxide initiator is 0.08-0.3% of the mass of the polypropylene resin.

[0012] Furthermore, in step (1), the comonomer is styrene; The amount of the comonomer used is 0.2-2% of the mass of the polypropylene resin; styrene has high reactivity with polypropylene macromolecular free radicals and can preferentially react with macromolecular free radicals to generate stable styrene free radicals, effectively inhibiting the β-chain scission side reaction of polypropylene during melt grafting and improving the grafting efficiency of glycidyl methacrylate.

[0013] Furthermore, in step (1), the temperature of the reaction extrusion is 180-210℃, the reaction extrusion is carried out in a twin-screw extruder, and the screw speed is 100-400 rpm.

[0014] Furthermore, in step (3), the power density of the online corona treatment is 50-500 W·min / m²; preferably, the power density is 100-300 W·min / m².

[0015] Furthermore, in step (4), the UV-curable coating composition comprises, by mass parts: 30-60 parts of polyurethane acrylate oligomer, 20-50 parts of reactive diluent, 2-6 parts of photoinitiator, 3-15 parts of nano-inorganic filler, and 0.5-3 parts of silane coupling agent.

[0016] Furthermore, the polyurethane acrylate oligomer is an aliphatic polyurethane acrylate.

[0017] Aliphatic polyurethane acrylate has excellent resistance to yellowing and transparency. After curing, it is colorless and transparent, and does not affect the visual effect of the underlying wood grain pattern.

[0018] Furthermore, the active diluent is selected from at least one of 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), and tripropylene glycol diacrylate.

[0019] Furthermore, the photoinitiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone (photoinitiator 184), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), and 2-hydroxy-2-methyl-1-phenylpropanone (photoinitiator 1173).

[0020] Furthermore, the nano-inorganic filler is selected from at least one of nano-silica, nano-alumina, and nano-zirconia; the average particle size of the nano-inorganic filler is 10-100 nm; preferably, the average particle size of the nano-inorganic filler is 20-50 nm.

[0021] Furthermore, the amount of the nano-inorganic filler used is 5-12 parts by weight.

[0022] Furthermore, the silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane (KH-550), γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), and γ-methacryloyloxypropyltrimethoxysilane (KH-570).

[0023] Furthermore, in step (4), the coating method is roller coating, spray coating or curtain coating, and the wet coating thickness is 5-50 μm; preferably, the wet coating thickness is 10-25 μm.

[0024] Furthermore, in step (5), the multi-stage gradient ultraviolet irradiation includes at least a first curing stage and a second curing stage, wherein the ultraviolet light intensity of the first curing stage is lower than that of the second curing stage.

[0025] Furthermore, the UV light intensity in the first curing stage is 50-150 mW / cm², and the UV light intensity in the second curing stage is 200-500 mW / cm².

[0026] Furthermore, the multi-stage gradient ultraviolet irradiation also includes a third curing stage, with an ultraviolet light intensity of 500-1000 mW / cm².

[0027] Furthermore, in step (5), the wavelength of the ultraviolet light source is 200-400 nm, and the total irradiation dose is 200-2000 mJ / cm².

[0028] Furthermore, in step (6), the heat treatment temperature is 70-90℃ and the treatment time is 0.5-4 hours.

[0029] In some embodiments, a black colorant is also added in step (1), and reacted with polypropylene resin, glycidyl methacrylate, peroxide initiator and comonomer at 170-230°C for extrusion; the coloring of the polypropylene matrix is ​​completed at the same time as introducing reactive epoxy groups on the polypropylene molecular chain. Step (2) also includes printing a wood grain pattern on at least one surface of the edge banding substrate.

[0030] The black colorant added in step (1) is uniformly dispersed in the polypropylene matrix throughout the extrusion molding process. The wood grain pattern is printed on the surface of the substrate, and the color of the black colorant is presented through the non-printed area of ​​the wood grain pattern.

[0031] Furthermore, the black colorant includes carbon black and black masterbatch, with the carbon black content accounting for 30-50% of the total black colorant and the black masterbatch amounting to 1-5% of the mass of polypropylene resin; preferably, the black masterbatch amounting to 2-4% of the mass of polypropylene resin.

[0032] The black masterbatch with polypropylene as the carrier has excellent compatibility with the polypropylene matrix resin in step (1). During the reactive extrusion process, it can be uniformly dispersed in the polypropylene melt, so that the resulting glycidyl methacrylate grafted polypropylene granules present a uniform deep black color, thereby forming a black edge-sealing substrate after extrusion molding in step (2). The black substrate serves as the base color to support the subsequent printing of wood grain patterns. The wood grain patterns are printed in light tones on the black base surface, and the black base is naturally revealed in the non-printed areas, forming the visual effect of black wood grain. This method of coloring exists throughout the polypropylene substrate rather than just on the surface has the advantages of color durability and not revealing the underlying color due to surface wear compared to the solution of printing black primer on the surface.

[0033] Furthermore, in step (2), the wood grain pattern is printed by gravure printing or digital inkjet printing; the printing ink is a weather-resistant UV-curable ink.

[0034] Wood grain patterns can be applied to a black substrate using gravure printing or digital inkjet printing, allowing for customization in various styles, from dark walnut and ebony to carbonized oak. The wood grain pattern is positioned above the black polypropylene substrate and below a transparent cross-linked functional layer, which provides long-lasting protection.

[0035] Secondly, this application provides a polypropylene edge banding tape with a photocurable functional layer, which is prepared by the preparation method described in the first aspect.

[0036] Furthermore, the polypropylene sealing tape with a photocurable functional layer has a two-layer structure, including a bottom layer and a top layer. The bottom layer is a glycidyl methacrylate-grafted polypropylene substrate, and the top layer is a transparent cross-linked functional layer. The top layer and the bottom layer are chemically bonded together.

[0037] In some embodiments, the polypropylene edge banding tape with a photocurable functional layer has a three-layer structure, including a bottom layer, a middle layer, and a top layer. The bottom layer is a black glycidyl methacrylate-grafted polypropylene substrate, the middle layer is a wood grain pattern printed on the surface of the black glycidyl methacrylate-grafted polypropylene substrate, and the top layer is a transparent cross-linked functional layer. The top layer and the bottom layer are chemically bonded together.

[0038] Compared with the prior art, the beneficial effects of this application include: This application introduces glycidyl methacrylate epoxy groups into the polypropylene molecular chain through reactive extrusion melt grafting. The active components in the subsequently coated UV-curable coating composition can undergo ring-opening reactions with the epoxy groups through their terminal hydroxyl or amine groups, establishing covalent chemical bonds between the coating and the polypropylene substrate, thus solving the problem of poor adhesion between the polypropylene substrate and the coating.

[0039] This application employs online corona treatment technology to further introduce oxygen-containing polar groups onto the surface of grafted polypropylene. This approach overcomes the limitations of simple corona treatment, which has a short duration of effect, and simple chemical grafting, which has a limited number of reaction sites on the surface.

[0040] This application employs a multi-stage gradient UV curing process. The low-intensity pre-curing stage provides sufficient reaction for interfacial chemical bonding, while the high-intensity curing stage ensures full cross-linking of the coating body, resulting in a functional gradient structure from the interfacial chemical bonding region to the highly cross-linked hardened surface region.

[0041] This application introduces nano-inorganic fillers into a UV-curable coating composition and modifies it with a silane coupling agent to make the nano-fillers uniformly dispersed in the cross-linked network, so that the resulting edge sealing tape has excellent surface properties.

[0042] This application combines the coloring of the polypropylene matrix with the chemical grafting of glycidyl methacrylate into a single process step by simultaneously adding a black colorant during the reactive extrusion process in step (1). This not only completes the chemical transformation of polypropylene from a non-polar material to a material containing reactive epoxy groups, but also imparts a uniform black base color to the substrate. This coloring method allows the black color to penetrate the entire thickness of the edge banding substrate and not be limited to the surface, fundamentally avoiding the problem of exposing the underlying color after the surface black coating wears off, and providing a stable and durable black base color for subsequent wood grain printing.

[0043] The transparent cross-linked functional layer of the edge banding tape prepared in this application has a partial shielding effect on ultraviolet light, which can effectively slow down the ultraviolet aging and fading of the black wood grain printing layer.

[0044] The edge banding tape produced in this application is environmentally friendly and safe, and contains no harmful substances. Attached Figure Description

[0045] The present application will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be construed as limiting the scope of this disclosure. Furthermore, unless specifically indicated, the drawings are only schematic representations of the composition or structure of the described objects and may contain exaggerated depictions, and the drawings are not necessarily drawn to scale.

[0046] Figure 1 This is a schematic diagram of the process flow for preparing the black wood grain polypropylene edge banding tape with a photocurable functional layer in the embodiments of this application.

[0047] Figure 2 This is a product image of a black wood grain polypropylene edge banding tape with a photocurable functional layer prepared according to an embodiment of this application. Detailed Implementation

[0048] The technical solution of this application is further described below through specific embodiments, but the scope of protection of this application is not limited to the following embodiments. Unless otherwise specified, the raw materials used in the embodiments of this application are all from conventional commercially available products.

[0049] Glycidyl methacrylate (GMA): Purity ≥97%, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0050] Dicumyl peroxide (DCP): Purity ≥ 99%, Merck Reagent Network; Styrene: Analytical grade, Sinopharm Chemical Reagent Co., Ltd.; Aliphatic polyurethane acrylate: Guangdong Haohui New Materials Co., Ltd.; 1,6-Hexanediol diacrylate (HDDA): Industrial grade, Changxing Chemical Industry Co., Ltd. Trimethylolpropane triacrylate (TMPTA): Industrial grade, Changxing Chemical Industry Co., Ltd.; 1-Hydroxycyclohexylphenyl ketone (Photoinitiator 184): Industrial grade, Tianjin Jiuri New Materials Co., Ltd. 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide (TPO): Industrial grade, Tianjin Jiuri New Material Co., Ltd.; γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560): Guangzhou Yuanda New Materials Co., Ltd.; Test methods Grafting rate determination: Fourier transform infrared spectroscopy (FTIR) was used, with polypropylene at 2722 cm⁻¹. -1 The CH combination peak at 1730 cm⁻¹ is used as an internal standard, based on the carbonyl group (C=O) of glycidyl methacrylate at 1730 cm⁻¹. -1 The relative grafting rate is calculated based on the area of ​​the characteristic absorption peak at the point.

[0051] Dyne value test: Tested according to ASTM D2578-23 standard.

[0052] Coating adhesion test: Refer to ISO2409:2013 standard, 0-5 grade, with grade 0 being the best.

[0053] Pencil hardness test: Refer to ISO 15184:2020 standard.

[0054] Tiber wear test: Refer to ISO 9352:2012 standard.

[0055] Peel strength test: Refer to ISO 4578:1997 standard.

[0056] Weathering resistance test: The weathering performance test was conducted in accordance with ISO 4892-3:2016, using a QUV fluorescent ultraviolet aging tester with a UVA-340 ultraviolet lamp, and the irradiance at 340nm was set to 0.76W / (m²). nm); the test cycle consisted of 8 hours of UV irradiation at 60℃ and 4 hours of condensation at 50℃, for a total aging time of 500 hours. The color difference ΔE of the samples before and after aging was determined according to the CIE Lab color space, with the color measurement conditions using a D65 standard light source and a 10° standard observation angle.

[0057] Hazardous substance testing: Refer to GB 18584-2024.

[0058] The specific implementation method of this application is as follows.

[0059] Example 1 This application provides a method for preparing a polypropylene edge-sealing tape with a photocurable functional layer, comprising the following steps: (1) Melt grafting 100 parts by weight of polypropylene resin, 2.0 parts by weight of glycidyl methacrylate, 0.15 parts by weight of dicumyl peroxide, 0.8 parts by weight of styrene, and 3.0 parts by weight of black colorant (40% carbon black content) were premixed in a high-speed mixer for 5 min. The mixture was then fed into a co-rotating twin-screw extruder with a screw diameter of 35 mm and an L / D ratio of 44 for reactive extrusion. The extruder temperatures were as follows: feeding section 170℃, melting section 185℃, mixing section 195℃, homogenizing section 200℃, and die section 195℃. The screw speed was 200 rpm. During this process, glycidyl methacrylate was grafted onto the polypropylene molecular chain under peroxide initiation, introducing reactive epoxy groups. Simultaneously, the black masterbatch was uniformly dispersed in the polypropylene melt, resulting in a uniformly dark black color throughout the polypropylene granules. The extrudate was water-cooled and pelletized to obtain black glycidyl methacrylate-grafted polypropylene granules. FTIR analysis showed that the relative grafting rate of glycidyl methacrylate was 1.6%.

[0060] (2) Extrusion molding The black glycidyl methacrylate grafted polypropylene granules obtained in step (1) were extruded through a single-screw extruder with a screw diameter of 45 mm and a sheet die to form a black edge-sealing tape substrate with a thickness of 1.0 mm and a width of 22 mm. The extrusion temperature was 180-200℃ and the traction speed was 10 m / min. The substrate was dark black throughout due to the uniform dispersion of the black masterbatch in step (1). During the traction process, an ebony wood grain pattern was gravure-printed on the upper surface of the black edge-sealing tape substrate using UV-curable wood grain ink. After printing, the pattern was immediately pre-cured and fixed by a UV lamp. The wood grain pattern was printed in a light tone on the surface of the black substrate, and the black background was naturally presented in the gaps and back of the wood grain pattern, forming a black wood grain visual effect.

[0061] (3) Corona treatment Online corona treatment is performed on the printed surface of the black wood grain edge banding substrate, with a power density of 200 W·min / m² and a distance of 0.5 m between the corona treatment station and the coating station.

[0062] (4) Apply UV-cured coating A transparent UV-curable coating composition was rolled onto the corona-treated printing surface. The wet coating thickness was 15 μm. The coating formulation consisted of 45 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate, 15 parts trimethylolpropane triacrylate, 2.5 parts photoinitiator 184, 2 parts 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2 parts γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and 8 parts nano-silica. The mixture was stirred at 800 rpm for 30 min under light-protected conditions, then dispersed at 1500 rpm for 20 min, and finally degassed by ultrasonication.

[0063] (5) Gradient UV curing The coated edge banding was sequentially passed through three UV curing zones at a linear speed of 10 m / min: low-pressure mercury lamp, 100 mW / cm², 2 s; medium-pressure mercury lamp, 300 mW / cm², 2 s; medium-pressure mercury lamp, 800 mW / cm², 1.5 s, wavelength 365 nm, cumulative dose approximately 1800 mJ / cm². After curing, the coating was colorless and transparent, and the underlying wood grain was clearly visible.

[0064] (6) Heat treatment By heat-treating the UV-cured edge banding in an 80℃ oven for 2 hours, a polypropylene edge banding with a UV-cured functional layer is obtained.

[0065] Example 2 The difference between this embodiment and embodiment 1 is that: in step (1), the amount of glycidyl methacrylate is adjusted to 1.0 parts by weight, dicumyl peroxide to 0.10 parts by weight, styrene to 0.5 parts by weight, black colorant to 3.0 parts by weight, and the relative grafting rate of glycidyl methacrylate is 0.8%, and the rest is the same as in embodiment 1.

[0066] Example 3 The difference between this embodiment and Embodiment 1 is that in step (1), the amount of glycidyl methacrylate is adjusted to 4.0 parts by weight, dicumyl peroxide to 0.30 parts by weight, styrene to 1.5 parts by weight, and black colorant to 3.0 parts by weight. The relative grafting rate of glycidyl methacrylate is 3.0%, and the rest is the same as in Embodiment 1.

[0067] Example 4 The difference between this embodiment and Embodiment 1 is that the amount of nano-silica in the coating is adjusted to 12 parts; the light intensity in the third curing stage is adjusted to 1000 mW / cm², and the rest is the same as in Embodiment 1.

[0068] Example 5 The difference between this embodiment and Embodiment 1 is that the wet coating thickness is adjusted to 25 μm, while the rest is the same as in Embodiment 1.

[0069] Comparative Example 1 This comparative example did not use glycidyl methacrylate grafting. Instead, 100 parts by weight of the original polypropylene resin and 3.0 parts by weight of the black colorant were mixed to replace the black glycidyl methacrylate grafted polypropylene. The rest was the same as in Example 1.

[0070] Comparative Example 2 Compared with Example 1, this comparative example did not perform step (3) corona treatment, but directly coated the substrate with UV-curable coating, and the rest was the same as Example 1.

[0071] Comparative Example 3 Compared with Example 1, the UV curing step (5) of this comparative example only uses one stage, 300 mW / cm², 5.5s, with a cumulative dose equivalent to that of Example 1, and the rest is the same as that of Example 1.

[0072] Comparative Example 4 Compared with Example 1, this comparative example did not add nano-SiO2, but was otherwise the same as Example 1.

[0073] Comparative Example 5 Compared with Example 1, in step (1) of this comparative example, the amount of glycidyl methacrylate used was 0.3 parts by mass, the amount of dicumyl peroxide used was 0.05 parts by mass, the amount of styrene used was 0.1 parts by mass, the relative grafting rate of glycidyl methacrylate was 0.2%, and the rest was the same as in Example 1.

[0074] Comparative Example 6 Compared to Example 1, in step (1) of this comparative example, the amount of glycidyl methacrylate used was 6.0 parts by weight, the amount of dicumyl peroxide was 0.60 parts by weight, and the amount of styrene was 2.5 parts by weight. The comparative example showed obvious yellowing of the material, gel particles, extrusion molding surface defects, and wood grain printing flaws, with a glycidyl methacrylate grafting rate of only 2.8%.

[0075] Comparative Example 7 Polypropylene edge sealing tape was prepared according to the scheme of Example 1 in CN121537889A.

[0076] Performance test results The edge banding tapes prepared in Examples 1-5 and Comparative Examples 1-7 were subjected to performance tests, and the results are shown in Tables 1-2.

[0077] Table 1. Performance test results of edge banding tape in each embodiment. Table 2. Performance test results of edge banding for each comparison sample "—" indicates that no valid data was obtained because the sample's appearance was unqualified or the item was not tested.

[0078] In Tables 1 and 2, the abbreviations represent the following meanings: DBP (dibutyl phthalate), BBP (butyl benzyl phthalate), DEHP (di(2-ethylhexyl) phthalate), DIBP (diisobutyl phthalate), DNOP (di-n-octyl phthalate), DINP (diisononyl phthalate), and DIDP (diisodecyl phthalate).

[0079] As shown in Tables 1 and 2, Comparative Example 1, which did not undergo glycidyl methacrylate grafting, exhibits a significant impact on adhesion compared to Example 1, as indicated by the melt grafting of glycidyl methacrylate. Comparative Example 1 achieved an adhesion grade of 4 and a peel strength of only 8.2 N / cm, while Example 1 achieved a grade of 0 and a peel strength of 27.6 N / cm. The epoxy groups of glycidyl methacrylate are a prerequisite for achieving chemical bonding between the coating and the substrate.

[0080] Comparative Example 2, which did not employ the corona treatment, showed a decrease in adhesion grade to 2 and peel strength to 20.5 N / cm. The combined effect of glycidyl methacrylate grafting and the corona treatment is essential for achieving good adhesion.

[0081] Comparative Example 3, which did not employ a gradient UV curing process, exhibited an adhesion grade of only 2 and a peel strength of 22.1 N / cm, indicating that the low-strength pre-curing stage in the gradient curing process provided sufficient interfacial reaction.

[0082] Comparative Example 4, without the addition of nano-silica, showed a decrease in hardness from 4H to H and an increase in wear resistance from 2.8 to 9.3 mg, indicating that the nanofiller significantly contributes to hardness and wear resistance.

[0083] Comparative Example 5 had an addition of 0.3% glycidyl methacrylate, a grafting rate of only 0.2%, an adhesion grade of 2, and a peel strength of 18.8 N / cm, indicating that the interfacial bonding sites were insufficient when the amount of glycidyl methacrylate was less than 0.5 parts by mass.

[0084] Comparative Example 6, with an addition of 6.0% glycidyl methacrylate, showed significant degradation and gelation defects, with the effective grafting rate decreasing to 2.8%, and also affecting the extrusion molding and wood grain printing quality.

[0085] Comparative Example 7 is inferior to this application in terms of hardness, abrasion resistance, and peel strength.

[0086] In Example 5, the dyne values ​​were all ≥44 dyn / cm, the adhesion was all grade 0, the pencil hardness was all ≥3H, the Tyber abrasion was all ≤3.5mg, the peel strength was all ≥24.1N / cm, and the ΔE was all ≤2.0. All indicators were within the ideal range.

[0087] Regarding the detection of hazardous substances, none of the ten hazardous substances in Examples 1-5 and Comparative Examples 1-5 were detected. The formulation of this application does not use components containing halogens, heavy metals, or phthalates. The polypropylene matrix resin does not contain halogens. The black masterbatch uses a polypropylene carrier and pure carbon black and does not contain heavy metal pigments. The aliphatic polyurethane acrylate and (meth)acrylate reactive diluents do not have aromatic structures. The photoinitiator 184 and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide do not contain heavy metals. The nano silica is a pure inorganic material.

[0088] It should be noted that in step (1) of this embodiment, the black masterbatch is directly colored in the polypropylene resin to make the entire edge banding substrate black. Those skilled in the art should understand that in other embodiments, other types of black colorants (such as carbon black powder directly added, black pigment, etc.) can also be used, as long as the resulting polypropylene substrate is black. This application does not make any special limitation on this.

[0089] In addition, the black masterbatch in step (1) of this embodiment can also be replaced by coloring agents of other colors.

[0090] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the embodiments above are only for the purpose of helping to understand the present application. It should be noted that those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method for preparing a polypropylene edge-sealing tape with a photocurable functional layer, characterized in that, Includes the following steps: (1) Melt grafting Polypropylene resin, glycidyl methacrylate, peroxide initiator, and comonomer are mixed in a certain proportion and reacted and extruded at 170-230℃ to introduce reactive epoxy groups into the polypropylene molecular chain, thus obtaining glycidyl methacrylate grafted polypropylene granules. (2) Extrusion molding The glycidyl methacrylate-grafted polypropylene granules obtained in step (1) are extruded through a sheet die to obtain the edge sealing tape substrate. (3) Corona treatment At least one surface of the edge banding substrate is subjected to online corona treatment to obtain a surface-activated edge banding substrate; (4) Apply UV-curable coating A UV-curable coating composition is applied to the surface of a corona-treated edge banding substrate to form a wet coating. (5) Gradient UV curing The coated edge banding is subjected to multi-stage gradient ultraviolet light irradiation to cure the wet coating and form a transparent cross-linked functional layer. (6) Heat treatment The edge sealing tape cured by ultraviolet light is heat-treated at 70-90℃ to obtain the polypropylene edge sealing tape with the light-cured functional layer.

2. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 1, characterized in that, In step (1), based on the mass of the polypropylene resin, the amount of glycidyl methacrylate used is 0.5-5% of the mass of the polypropylene resin; In step (1), the peroxide initiator is selected from at least one of dicumyl peroxide, benzoyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane; the amount of the peroxide initiator is 0.05-0.5% of the mass of the polypropylene resin. In step (1), the comonomer is styrene; the amount of the comonomer is 0.2-2% of the mass of the polypropylene resin.

3. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 1, characterized in that, In step (1), the temperature of the reactive extrusion is 180-210℃, and the reactive extrusion is carried out in a twin-screw extruder with a screw speed of 100-400 rpm; In step (3), the power density of the online corona treatment is 50-500 W·min / m²; In step (4), the coating method is roller coating, spray coating or curtain coating, and the wet coating thickness is 5-50 μm; preferably, the wet coating thickness is 10-25 μm. In step (5), the wavelength of the ultraviolet light source is 200-400 nm, and the total irradiation dose is 200-2000 mJ / cm². In step (6), the heat treatment temperature is 70-90℃ and the treatment time is 0.5-4 hours.

4. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 3, characterized in that, In step (5), the multi-stage gradient ultraviolet irradiation includes at least a first curing stage and a second curing stage. The ultraviolet light intensity in the first curing stage is 50-150 mW / cm², and the ultraviolet light intensity in the second curing stage is 200-500 mW / cm².

5. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 4, characterized in that, In step (5), the multi-stage gradient ultraviolet irradiation also includes a third curing stage, with an ultraviolet light intensity of 500-1000 mW / cm².

6. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 1, characterized in that, In step (4), the UV-curable coating composition comprises, by mass parts: 30-60 parts of polyurethane acrylate oligomer, 20-50 parts of reactive diluent, 2-6 parts of photoinitiator, 3-15 parts of nano-inorganic filler and 0.5-3 parts of silane coupling agent.

7. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 6, characterized in that, The polyurethane acrylate oligomer is an aliphatic polyurethane acrylate. The reactive diluent is selected from at least one of 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, tripropylene glycol diacrylate, and tripropylene glycol diacrylate. The photoinitiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, and 2-hydroxy-2-methyl-1-phenylpropanone; The nano-inorganic filler is selected from at least one of nano-silica, nano-alumina, and nano-zirconia; the average particle size of the nano-inorganic filler is 10-100 nm. The silane coupling agent is selected from at least one of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

8. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 1, characterized in that, In step (1), a black colorant was also added, and the reaction was carried out with polypropylene resin, glycidyl methacrylate, peroxide initiator and comonomer at 170-230℃. Furthermore, step (2) also includes printing a wood grain pattern on at least one surface of the edge banding substrate.

9. The method for preparing polypropylene edge-sealing tape with a photocurable functional layer as described in claim 8, characterized in that, The black colorant includes carbon black and black masterbatch, with carbon black accounting for 30-50% of the total black colorant content and black masterbatch accounting for 1-5% of the mass of polypropylene resin. The wood grain pattern is printed using gravure printing or digital inkjet printing. The printing ink is a weather-resistant UV-curable ink.

10. A polypropylene edge-sealing tape with a photocurable functional layer, characterized in that, The polypropylene edge banding with a photocurable functional layer is prepared by the preparation method according to any one of claims 1 to 9.

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