A method for preparing photocurable abrasive belts

Abstract

This invention discloses a method for preparing photocurable abrasive belts, belonging to the field of photocurable abrasive belt technology. The method includes the following steps: providing a raw abrasive belt fabric base; applying a reinforcing functional primer between the roller coating layers on the working surface of the raw abrasive belt fabric base; pre-curing the primer under ultraviolet light to form an active anchoring layer with unreacted active polar groups, thus obtaining a pretreated fabric base; coating the surface of the active anchoring layer of the pretreated fabric base with a photocurable primer to form a photocurable primer layer, wherein the photocurable primer is a free radical-cationic hybrid photocurable system, and the coating amount is 60~130 g / m². 2 Inorganic abrasives are oriented vertically and directionally implanted into the uncured photocurable primer layer under a high-voltage electrostatic field to form an oriented abrasive layer; the substrate after abrasive implantation is placed in a first curing chamber and subjected to initial curing by cold light source radiation using a first ultraviolet light source; a photocurable topcoat is then applied to the surface of the initially cured oriented abrasive layer, with a coating amount of 50~110 g / m². 2 The substrate after coating with adhesive is sent into the second curing chamber. First, the surface drying of the photocurable adhesive is initiated by irradiation with a second ultraviolet light source. Then, the substrate is irradiated and heated by a stepped energy field that combines ultraviolet light irradiation and infrared thermal radiation. After curing, the substrate is mechanically softened, cut into strips, and joined together to obtain the photocurable sand belt.

Description

Technical Field

[0001] This invention relates to the field of photocurable abrasive belt technology, and more specifically to a method for preparing photocurable abrasive belt. Background Technology

[0002] Traditional abrasive belt manufacturing processes typically use phenolic resin or modified epoxy resin as the base and top coat. After coating and embedding the abrasive, the belt needs to be placed in a traditional hanging drying tunnel stretching hundreds of meters long for 4 to 8 hours at temperatures reaching 120°C to 140°C. This traditional thermosetting process not only consumes a great deal of energy, has a long production cycle, and requires a huge amount of land, but also inevitably releases large amounts of free formaldehyde and phenol at high temperatures, resulting in the emission of large amounts of volatile organic compounds (VOCs), leading to serious air pollution and extremely high safety and environmental costs.

[0003] In recent years, with the development of radiation curing technology, UV curing technology has been introduced into the abrasive manufacturing industry due to its significant technological advantages, such as "second-level drying, energy saving, zero VOC, and small footprint." However, because the coating of heavy-duty grinding belts is relatively thick (typically the thickness of the base adhesive plus the top adhesive reaches hundreds of micrometers), and the abrasive particles (such as ceramic corundum, silicon carbide, etc.) are themselves opaque hard solids, they have a strong refraction, absorption, and shielding effect on ultraviolet light. This means that when conventional free radical UV curing systems are exposed to ultraviolet light, photons can only penetrate the surface top adhesive layer, while the base adhesive at the bottom of the abrasive layer is completely in the "shadow zone" and cannot obtain sufficient photon excitation, resulting in a serious defect of "incomplete bottom curing (deep uncured)." In high-speed (25~35 m / s) heavy-duty grinding, once the abrasive belt is subjected to strong shear force and bending stress, the adhesive layer is very prone to interlayer brittle fracture, peeling, or large-area "whole layer detachment (abrasive shedding)" at the root of the abrasive, causing the abrasive belt to fail instantly. Therefore, how to eliminate the light-shielding effect of abrasives and achieve high-strength full cross-linking of the deep layer of photocured heavy-duty abrasive belts is a key technical bottleneck that has been difficult to overcome in this field for a long time. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a method for preparing photocurable abrasive belts.

[0005] The objective of this invention can be achieved through the following technical solutions: A first aspect of the present invention relates to a method for preparing photocurable abrasive belts, comprising the following steps: S1. Provide the original abrasive belt fabric base, and apply an enhanced functional primer between the roller coatings on the working surface of the original abrasive belt fabric base. Pre-cur the primer under ultraviolet light to form an active anchoring layer with unreacted active polar groups, thus obtaining a pre-treated fabric base. S2. A photocurable primer is coated on the surface of the active anchoring layer of the pretreated fabric to form a photocurable primer layer. The photocurable primer is a free radical-cationic hybrid photocurable system, and the coating amount is 60~130 g / m2. S3. Under a high-voltage electrostatic field, inorganic abrasives are oriented and vertically implanted into the uncured photocurable base layer to form an oriented abrasive layer; S4. The substrate after sand planting is sent into the No. 1 curing box and cold light source radiation is used for initial curing to make the surface of the photocurable base layer cross network locking and lock the root of the inorganic abrasive in situ, and keep the lower layer of the photocurable base layer in a semi-cured state, retaining the reactivity of the cationic components therein. S5. Apply a light-cured adhesive to the surface of the directional abrasive layer after initial curing, with a coating amount of 50~110 g / m2. S6. The substrate after coating with adhesive is sent into the second curing chamber. First, the surface of the photocurable adhesive is irradiated by the second ultraviolet light source. Then, the substrate is irradiated and heated by a stepped energy field that combines ultraviolet light irradiation and infrared thermal radiation, which triggers the cationic dark reaction in the deep layer of the photocurable base adhesive, causing the deep base adhesive that is blocked by the inorganic abrasive to crosslink and cure. After curing, the substrate is mechanically softened, cut into strips, and joined together to obtain the photocurable abrasive belt.

[0006] Optionally, in step S1, the original fabric of the sanding belt is a Ywt or Xwt grade all-polyester waterproof fabric; the interlayer reinforcing primer is composed of the following raw materials in parts by weight: 60 parts of polyurethane acrylate oligomer, 15 parts of phosphoric acid esterified acrylate adhesion promoter, 20 parts of reactive diluent monomer, and 5 parts of free radical photoinitiator; the coating amount of the interlayer reinforcing primer is 15~30 g / m². 2 .

[0007] Optionally, in step S2, the free radical-cationic hybrid photocuring system is composed of the following raw materials in parts by weight: 35-48 parts of alicyclic epoxy resin, 28-40 parts of hydroxyl-terminated modified polyurethane acrylate, 8-15 parts of polyol, 10 parts of isobornyl acrylate, 3 parts of sulfonium salt cationic photoinitiator, and 2 parts of free radical photoinitiator.

[0008] Optionally, the sulfonium salt cationic photoinitiator is a triarylsulfonium salt photoinitiator, the free radical photoinitiator is an α-hydroxy ketone photoinitiator, and the polyol is polytetrahydrofuran diol.

[0009] Optionally, in step S3, the inorganic abrasive is one or more of silicon carbide, white corundum, brown corundum, and microcrystalline ceramic abrasive, and the particle size of the inorganic abrasive is P60~P600 mesh; the process parameters of the electrostatic sand planting are: high voltage electrostatic field voltage of 30~55 kV, and electrode spacing of 80~130 mm.

[0010] Optionally, in step S4, the first ultraviolet light source is an LED-UV cold light source with a central radiation wavelength of 365 nm or 395 nm and a radiation energy density of 150~350 mJ / cm². 2 .

[0011] Optionally, in step S5, the photocurable adhesive is composed of hyperbranched polyurethane acrylate oligomer, nano-silica modified acrylate resin, silane coupling agent grafted abrasive additive and composite photoinitiator, with a solid content of 100%.

[0012] Optionally, in step S6, the second curing chamber is equipped with a UV-LED array lamp group, a high-pressure and medium-pressure mercury lamp group, and a far-infrared heating plate; the irradiation process of the stepped energy field is as follows: first, the UV-LED array lamp group with a wavelength of 395 nm is used at 400~600 mJ / cm 2 The energy initiates the surface drying of the photocurable adhesive, and then the high-pressure mercury lamp assembly applies 1200~2500 mJ / cm². 2 The full spectrum of energy is radiated, and the far-infrared heating plate is turned on simultaneously to keep the local substrate temperature of the photocurable base layer at 80~110 ℃ for 1~3 minutes.

[0013] Optionally, in step S6, the mechanical softening is: repeatedly stretching and bending the cured abrasive belt in different directions using 90-degree and 180-degree roller bending softening machines.

[0014] A second aspect of the present invention relates to a photocurable abrasive belt, wherein the photocurable abrasive belt is prepared by the preparation method according to any one of claims 1 to 9; after running for 150 hours under a heavy-load continuous wet grinding test with a grinding linear speed of 28 m / s and a load pressure of 0.4 MPa, the photocurable abrasive belt exhibits a delamination and cracking rate of no more than 0.3%, an abrasive loss volume percentage of no more than 1.2%, and a grinding efficiency retention rate of more than 80% of the initial efficiency.

[0015] The beneficial effects of this invention are: 1. Completely overcomes the industry-wide problem of "light shielding by opaque abrasive layers" (Comparative Example 1): Comparative Example 1 uses a traditional pure free radical photocuring system. Although its manufacturing energy consumption is extremely low (only 8.5 kWh), its adhesive is highly dependent on the activation of direct ultraviolet photons. The opaque inorganic abrasive blocks more than 80% of the photons in the lower layer after sanding. As a result, in less than 20 hours of grinding test, the bottom adhesive, lacking any curing strength, underwent catastrophic large-area delamination and tearing under high-speed bending and shearing, with an adhesive layer delamination rate as high as 38.5%, and a large amount of abrasive peeling off (sand loss rate 24.6%), causing the grinding efficiency to drop drastically to 22.3%. In contrast, Examples 1-8 of this invention scientifically introduce cationic curing components. After ultraviolet light instantly excites super-strong proton acids, even if the photons are blocked by the abrasive shield, the proton acids can still spontaneously diffuse in the shadow area and the bottom adhesive in the form of active centers to carry out dark reactions. The macroscopic performance shows that the delamination and cracking rate of the abrasive belt is close to 0%, and the abrasive loss volume is successfully controlled within 1.2%, perfectly achieving industrial-grade heavy-duty long-life grinding with UV-cured abrasive belts.

[0016] 2. This fully demonstrates the decisive scientific mechanism of "synergistic initiation by light-thermal energy fields" (Comparative Example 2): Although Comparative Example 2 used a free radical-cationic hybrid resin, the cation reactivity was extremely slow without the support of heat energy because infrared heating was turned off in the main curing chamber. The proton acid diffusion and migration rate was low, and only local weak cross-linking occurred in the shaded area within the limited curing time. As a result, after 150 hours of polishing, its resistance to wet polishing swelling was severely insufficient, with 14.2% of the adhesive layer showing internal cracking and 9.8% showing local peeling, and the polishing efficiency was halved. In contrast, Examples 1-8 of this invention, through the stepwise synergy of matching infrared thermal energy (80℃ ~ 110℃) and high-energy ultraviolet light, increased the flexibility of the resin matrix molecular chain segments, and the proton acid diffusion rate increased exponentially, inducing high-density deep full cross-linking of cations in the shaded area within 2 to 3 minutes.

[0017] 3. Outstanding economic and low-carbon benefits: The whole-process photocuring production process of this invention ensures that the sanding quality and service life are comparable to (or even surpass) those of traditional thermocuring phenolic sanders. At the same time, by completely eliminating several hours of high-temperature wire baking, the energy consumption for manufacturing 100 square meters is reduced from hundreds of kilowatt-hours in the traditional process to 11.5 ~ 17.2 kWh, which increases the production efficiency by dozens of times. Moreover, it truly achieves zero free formaldehyde and zero VOC emissions throughout the entire process, and has the prospect of green and low-carbon industrial application. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0019] Example 1 S1. Substrate pretreatment: Select Ywt grade polypolyester fully waterproof abrasive belt cloth base, and uniformly roll-coat 20 g / m² onto the working surface. 2 An interlayer enhancing primer (composed of 60 wt% polyurethane acrylate, 15 wt% phosphated acrylate adhesion promoter, 20 wt% reactive acrylic monomer, and 5 wt% TPO free radical photoinitiator). It was tested using a high-pressure mercury lamp with an energy of 100 mJ / cm². 2 Surface pre-curing is performed to form a hard and tough anchoring layer with unreacted active polar groups.

[0020] S2. Applying the primer: A layer of flexible, high-toughness, light-cured primer is evenly applied to the surface of the active anchoring layer, with a coating amount of 90 g / m². 2 The primer formulation is as follows: 40 parts of alicyclic epoxy resin (ERL-4221), 35 parts of hydroxyl-terminated modified polyurethane acrylate, 10 parts of polytetrahydrofuran diol (PTMEG), 10 parts of reactive diluent IBOA, 3 parts of cationic initiator triarylsulfonium salt (CPI-6976), and 2 parts of free radical initiator 1173.

[0021] S3. Electrostatic Abrasive Planting: The cloth substrate is sent into the electrostatic abrasive planting chamber. Under the conditions of an electrostatic field voltage of 40 kV and an electrode spacing of 110 mm, P120 mesh silicon carbide abrasive is vertically implanted into the uncured base layer from bottom to top.

[0022] S4. Initial Curing of Primer: The substrate enters the No. 1 curing chamber and is irradiated with a 395 nm wavelength LED-UV cold light source with an energy density of 220 mJ / cm². 2 At this point, the free radical components on the surface of the base adhesive quickly solidify and set, firmly locking the root of the abrasive in situ. However, the lower cationic components do not undergo severe reaction and remain in a semi-cured, tough state.

[0023] S5. Coating and Recoating: A high-abrasion-resistant, UV-curable coating with 100% solids content is uniformly roller-coated onto the surface of the directional abrasive layer, with a coating weight of 75 g / m². 2 (The main components are hyperbranched multifunctional polyurethane acrylate resin compounded with nano-silica).

[0024] S6. Multiple Deep Curing and Post-treatment: The sanding belt is fed into the No. 2 curing chamber for a stepped "light-heat" synergistic energy field treatment. First, it is radiated with 500 mJ / cm² energy by a 395 nm LED-UV lamp assembly. 2 Lock the surface coating; then immediately subject it to high-energy radiation (energy up to 1800 mJ / cm²) through the full spectrum of a medium- or high-pressure mercury lamp. 2 Simultaneously, the far-infrared heating plate is activated to maintain the substrate temperature at 95℃ for 2 minutes. Under these conditions, the photo-excited cationic initiator, under the strong catalysis of thermal energy, overcomes the light shielding barrier of the abrasive and undergoes efficient deep spontaneous cross-linking (dark reaction) in the "light-shadow zone." After the abrasive belt is cooled from the furnace, it undergoes mechanical softening treatment using a 180-degree roller mill, and is then slit and joined into finished abrasive belts.

[0025] Example 2 (Ceramic-cured abrasive belt for heavy-duty grinding of stainless steel plates) S1. Substrate pretreatment: Xwt grade heavy-duty polyester waterproof fabric is selected, and a reinforcing primer of 30 g / m² is applied to the surface. It is then pre-cured by ultraviolet radiation.

[0026] S2 ~ S3, Primer and Sand Reeling: The alicyclic epoxy resin in the primer formulation was adjusted to 45 parts, and the hydroxyl-terminated modified polyurethane acrylate to 30 parts. The primer coating weight was increased to 125 g / m². 2 The abrasive material is a mixed microcrystalline ceramic corundum with P80 mesh, the electrostatic sand-planting voltage is increased to 50 kV, and the electrode spacing is 95 mm.

[0027] S4 ~ S5, Initial Curing and Recoating: Initial curing uses a 365 nm LED-UV light source with a radiation energy density of 300 mJ / cm². 2 Subsequently, a high-abrasion-resistant UV-cured adhesive is applied, with a coating amount of 105 g / m². 2 .

[0028] S6, Stepped Main Curing: The radiation energy of the high-pressure mercury lamp in the No. 2 curing chamber is increased to 2400 mJ / cm². 2 The far-infrared heating plate temperature was adjusted to 110℃, and the heat-induced dark reaction time was extended to 3 minutes. Heavy-duty ceramic abrasive belts were manufactured through multi-directional mechanical stress softening and strip cutting and butt welding.

[0029] Example 3 (Fine UV-cured abrasive belt for high-polish precision hardware processing) S1 ~ S3, Substrate, Primer and Sand Reinforcement: Use lightweight polyester waterproof fabric as the base, with a primer application rate of 15 g / m². 2The primer formulation contains 35 parts alicyclic epoxy resin, 40 parts hydroxyl-terminated modified resin, and 15 parts polyol. The primer coating amount is controlled at 65 g / m². P320 mesh fine white corundum abrasive is used, with an electrostatic abrasive voltage of 35 kV and an electrode spacing of 120 mm.

[0030] S4 ~ S6, Initial Curing and Re-coating Main Curing: Initial curing LED energy is 160 mJ / cm² 2 The coating application rate is 55g / m². 2 The energy of the main curing mercury lamp in the No. 2 curing chamber is controlled at 1400 mJ / cm². 2 The far-infrared heating plate is set to 85℃ for 1.5 minutes. After being lightly softened by a 90-degree roller and cut into strips, it is made into a fine polishing abrasive belt.

[0031] Example 4 (High-strength UV-cured sanding belt for moisture-resistant sanding) S1 ~ S3, Previous Processes: In step S1, the primer coating amount is 25 g / m². 2 In step S2, the primer uses a free radical-cationic system, with a coating amount of 100 g / m². 2 Step S3 uses P240 mesh brown corundum abrasive with an electrostatic field voltage of 42 kV.

[0032] S4-S6, Post-curing process: In step S4, the initial curing LED-UV energy is 250 mJ / cm². In step S5, the coating amount is 85 g / m². 2 In step S6, the main curing process, the total spectral radiation energy of the mercury lamp is 2000 mJ / cm², the infrared temperature control heating is maintained at 100℃, and the heat-assisted curing time is 2 minutes.

[0033] Example 5 (Medium-mesh ceramic abrasive wear-resistant belt) S1 ~ S3, Previous process: Primer coating amount is 22 g / m 2 The primer formulation contains 42 parts alicyclic epoxy resin, 33 parts hydroxyl-terminated modified polyurethane acrylate, and 12 parts polyol. The primer coating weight is 110 g / m². 2 The abrasive material used is P180 mesh microcrystalline ceramic corundum, with an electrostatic abrasive voltage of 45 kV and a plate spacing of 105 mm.

[0034] S4 ~ S6, Post-processing: Initial curing uses a 395 nm LED-UV light source with a radiation energy density of 240 mJ / cm². 2 The high-abrasion-resistant UV-cured adhesive coating has a coverage of 80 g / m². 2 The main curing temperature gradient is controlled at 520 mJ / cm² for UV-LED radiation. 2Subsequently, the high-pressure mercury lamp emitted 1900 mJ / cm². 2 It is also combined with far-infrared temperature control at 98℃, and the heat-assisted reaction lasts for 2 minutes.

[0035] Example 6 (Fine silicon carbide abrasive belt for polishing non-ferrous metals) S1 ~ S3, Substrate and Coating: Ywt grade polyester waterproof fabric is selected, with a primer coating amount of 18 g / m². 2 The amount of primer applied should be controlled at 75 g / m². 2 The formulation contains 38 parts alicyclic epoxy resin and 38 parts hydroxyl-terminated modified polyurethane acrylate. P400 mesh silicon carbide fine abrasive is used, with an electrostatic abrasive voltage of 38 kV and an electrode spacing of 115 mm.

[0036] S4 ~ S6, Initial Curing and Main Curing: Initial curing LED energy is 180 mJ / cm². 2 The coating weight is 60 g / m². 2 The energy consumption of the full-spectrum mercury lamp in the No. 2 curing chamber was adjusted to 1500 mJ / cm². 2 Infrared temperature control heating is set to 90℃, and thermal initiation of cationic dark reaction curing lasts for 1.5 minutes. After stretching, bending, and softening, it is rolled up.

[0037] Example 7 (Heavy-duty high-cutting-value corundum composite abrasive belt) S1 ~ S3, Process formulation: Fabric pretreatment primer application rate is 28 g / m² 2 The base coat application rate has been increased to 120 g / m². 2 The main components include 48 parts alicyclic epoxy resin, 28 parts hydroxyl-terminated modified resin, and 8 parts polyol. P60 mesh coarse-grained brown corundum abrasive was selected, with an electrostatic abrasive voltage of 52 kV and an electrode spacing of 85 mm.

[0038] S4 ~ S6, Curing Process: Initial curing uses a 365 nm wavelength light source with an energy density of 320 mJ / cm². 2 The coating application rate is 100 g / m². 2 The radiation dose of the main curing high-energy mercury lamp was set to 2300 mJ / cm². 2 The temperature is raised to 105°C using an infrared heating plate, and the reaction lasts for 2.5 minutes.

[0039] Example 8 (Polycrystalline white corundum fine abrasive belt for polishing automotive paint) S1 ~ S3, Basic Configuration: Uses ultra-flexible waterproof fabric base, primer application rate 16 g / m² 2 The base coat application rate is 70g / m². 2The resin matrix formulation contains 40 parts alicyclic epoxy resin and 15 parts polyol. P600 mesh ultrafine polycrystalline white corundum abrasive is selected, with an electrostatic abrasive voltage of 32 kV and an electrode spacing of 125 mm.

[0040] S4 ~ S6, Double Curing: Initial curing LED-UV radiation energy is 150 mJ / cm² 2 The coating amount using the roller is 50 g / m². 2 The total energy of the ultraviolet high-pressure mercury lamp radiation during the main curing stage was 1300 mJ / cm². 2 Infrared heating is used to control the temperature at 80℃ for 1.5 minutes. After softening and moisture-proof curing, the parts are cut and joined together.

[0041] Comparative Example 1 (Control group lacking spontaneous deep dark reaction system with cations) The remaining substrates, abrasive ratios, and process steps are completely identical to those in Example 1, except that the flexible high-toughness primer in step S2 and the topcoat in step S5 completely abandon the free radical-cationic hybrid curing system, and instead use a conventional industrial-grade pure free radical type all-acrylate photocurable resin system (composed of 75 parts pure acrylate oligomer, 20 parts reactive diluent monomer, and 5 parts free radical photoinitiator TPO). During curing, the spontaneous extension characteristics of the cationic dark reaction cannot be utilized.

[0042] Comparative Example 2 (Group lacking infrared thermal assistance and stepped energy field solidification control) The remaining materials, chemical formulas, and processes are completely identical to those in Example 1. The only difference is that during the main curing in step S6, after the sanding belt is placed into the No. 2 curing chamber, the far-infrared heating plate is completely shut off (i.e., no external thermal energy is provided for catalytic assistance). Instead, the material is irradiated with unidirectional ultraviolet light by a high-pressure mercury lamp at room temperature (cold source chamber, approximately 28°C to 35°C) (the total input light energy remains the same at 1800 mJ / cm²). 2 ).

[0043] Comparative Example 3 (Control group lacking the "semi-curing lock-in - retaining deep activity" initial curing strategy) The remaining substrates, abrasive ratios, chemical formulations, and curing processes are completely identical to those in Example 1. The only difference is that in step S4, during the initial curing of the primer, the initial curing strategy of "using a low-energy cold light source to only cause local cross-network locking on the surface of the primer layer, while the underlying cationic components maintain a semi-cured tough state" of this invention is not adopted. Instead, the radiation energy density of the first ultraviolet light source (395nm LED-UV) is increased from 220 mJ / cm². 2 Significantly increased to 1600 mJ / cm 2Simultaneously, the far-infrared heating plate is turned on, causing the base layer to undergo deep hardening and cross-linking during the initial curing stage after electrostatic sand planting and before the coating of the top adhesive. As a result, the reactive sites of the cationic components under the base layer are consumed in advance during the initial curing stage, and the toughness of the matrix is ​​lost in advance. By the time of the main curing in step S6, there are no sufficient cationic active centers and reactive spaces in the abrasive shadow area for far-infrared thermal energy to catalyze the extension to the depth. The "dark reaction extension channel" on which this invention relies to overcome deep light shielding is blocked in advance.

[0044] Comparative Example 4 The remaining primer formulation, abrasive ratio, curing process, and post-treatment steps are completely identical to those in Example 1. The only difference is that the interlayer reinforcing primer roll coating and UV pre-curing treatment in step S1 are omitted. That is, the fabric substrate working surface no longer forms a "hard and tough anchoring layer with unreacted active polar groups." Instead, the flexible, high-toughness UV-cured primer from step S2 is directly applied to the original fabric substrate working surface. As a result, the chemical bonding interface provided by the active polar groups of the phosphated acrylate adhesion promoter is missing between the fabric substrate and the primer. The interlayer bonding relies solely on the physical wetting of the fabric substrate by the primer.

[0045] Comparative Example 5 The remaining substrates, abrasive ratios, and process steps are completely identical to those in Example 1. The difference lies in the simultaneous omission of two core methods of this invention: First, both the primer in step S2 and the topcoat in step S5 use the same conventional industrial-grade pure free radical type all-acrylate photocurable resin system as in Comparative Example 1 (composed of 5 parts pure acrylate oligomer, 20 parts reactive diluent monomer, and 5 parts free radical photoinitiator TPO); Second, during the main curing in step S6, the far-infrared heating plate is completely shut off as in Comparative Example 2, and unidirectional ultraviolet light irradiation is performed only once at room temperature (cold source chamber, approximately 28℃~35℃) by a high-pressure mercury lamp (the total input light energy is maintained at the same 1800 mJ / cm). 2 This group has neither cationic components that can extend the dark reaction, nor thermal energy that promotes deep diffusion.

[0046] To scientifically and clearly demonstrate the significant and substantial advancements of the photocuring preparation method of this invention in overcoming "deep light shielding," the abrasive belts produced in Examples 1-8 and Comparative Examples 1-5 were cut into finished abrasive belts with a uniform specification of 2100mm × 50mm. Heavy-duty cyclic grinding tests were conducted on thick standard stainless steel plates and hard marble on a heavy-duty rigid linkage grinder (test parameters: abrasive belt drive linear speed 28 m / s, contact impact load pressure 0.4MPa, continuous cooling wet grinding with water spray). After 150 hours of continuous high-intensity grinding, several core performance indicators were quantitatively evaluated, and the test results are shown in Table 1. Table 1: Comprehensive Performance Test Data of the Photocurable Abrasive Belt Examples and Comparative Examples of the Invention To directly verify the effect of the present invention in achieving deep full cross-linking in the light and shadow area at the bottom of the opaque abrasive layer, samples of the silicon carbide (P120) photocurable abrasive belt prepared in Example 1 were taken and subjected to the following microscopic curing degree characterization.

[0047] 1. Sample preparation and region definition The finished abrasive belt from Example 1 was subjected to cryogenic liquid nitrogen brittle fracture, and cross-sectional samples perpendicular to the abrasive belt plane were prepared using argon ion beam cross-section polishing (CP). The area of ​​the base adhesive directly below the abrasive particles and completely blocked by the vertical projection of the abrasive particles was defined as the "shadow zone" (the most unfavorable area for deep curing); the area of ​​the base adhesive between adjacent abrasive particles, where ultraviolet light can directly reach, was defined as the "light-receiving zone" (control); and the "surface layer" near the base adhesive and the "bottom layer" near the fabric base were distinguished along the thickness direction of the base adhesive layer. To demonstrate relative advantages, samples from the same position in Comparative Example 2 (hybrid system but with far-infrared heat turned off) were used as parallel controls.

[0048] 2. Gel content (solvent extraction rate) along the depth gradient Samples were taken from both the surface and bottom layers along the thickness direction of the base layer. Soxhlet extraction was performed at 65°C for 24 hours using tetrahydrofuran (THF) as the solvent. The percentage of insoluble crosslinked components was calculated as follows: gel content (%) = (dry weight after extraction ÷ dry weight before extraction) × 100%. Higher gel content indicates more complete crosslinking. In Example 1, the gel content of the bottom layer and the surface layer were extremely close with a small difference (only 1.3%), indicating that the degree of cross-linking in the deep layer was comparable to that in the surface layer; in Comparative Example 2, the gel content of the bottom layer was significantly lower than that in the surface layer (the difference reached 32.4%), indicating that the deep layer curing was insufficient.

[0049] 3. Nanoindentation microhardness gradient along depth Microhardness and elastic modulus were measured point by point on the cross-section from the surface to the bottom layer (including light and shadow areas) using a nano indenter (model Nano Indenter G200): Example 1 shows a uniform hardness distribution from the surface to the shaded area and a high retention rate in the shaded area (reaching 95.5% of the surface hardness); Comparative Example 2 shows a significantly lower hardness in the shaded area (only 33.3% of the surface hardness), confirming that the deeper layers are under-cured.

[0050] 4. FTIR epoxy group conversion rate Micro-FTIR was used to measure the primer spectra in the light-exposed and light-shadowed areas. The peak area attenuation of the characteristic absorption peaks of alicyclic epoxy groups was used, and the carbonyl peak (approximately 1720 cm⁻¹), which remained unchanged before and after curing, was used as an internal standard. The degree of cationic ring-opening crosslinking was calculated using the formula: epoxy conversion rate (%) = [1 - (Aepoxy / Acarbonyl) after curing ÷ (Aepoxy / Acarbonyl) before curing] × 100%. Results: In Example 1, the epoxy conversion rate in the light-exposed area was 95.1%, and in the light-shadowed area it was 93.5% (the two are very close, indicating that the light shielding effect has virtually no negative impact on the spontaneous ring-opening of the cationic primer); in Comparative Example 2, the conversion rate in the light-shadowed area was only 48.2%. This result directly shows that the cationic component of this invention still completed a high degree of epoxy ring-opening crosslinking in the deep shadowed area shielded by the abrasive.

[0051] 5. DSC residual enthalpy of solidification Samples of the primer in the shaded area were subjected to differential scanning calorimetry (DSC) with programmed temperature rise. The residual enthalpy of curing, ΔHresidual, was measured and compared with the total enthalpy of curing of the completely uncured system of the same formulation, ΔH0. The degree of curing (%) was calculated as (1 - ΔHresidual ÷ ΔH0) × 100%. The results showed that the residual enthalpy in the shaded area of ​​Example 1 was 10.5 J / g, corresponding to a degree of curing of 96.8%; while the residual enthalpy in the shaded area of ​​Comparative Example 2 was 138.4 J / g, with a degree of curing of 56.2%. A lower residual enthalpy indicates more complete consumption of reactive groups.

[0052] 6. Dark reaction curing degree-time curve (verifies that deep cross-linking is basically completed within 1~3 min) Starting from step S6, the main curing process (maintaining the substrate temperature at 95°C using far-infrared radiation), samples were taken at 0.5, 1, 1.5, 2, 2.5, 3, and 5 minutes, and after 24 hours of moisture-proof curing, to measure the degree of curing in the shaded areas (characterized by gel content or epoxy conversion rate). Curing degree-time curves were plotted. The results showed that the degree of curing in the shaded areas reached a plateau value of 95.2% at approximately 2 minutes, and there was no significant further increase thereafter (including 24 hours of moisture-proof curing) (the difference between the 2-minute value and the value after curing was only 0.3%), indicating that the cationic deep dark reaction was basically completed within 1-3 minutes of the main curing process; while the moisture-proof curing process in Example 8 only served a moisture-proof function and no longer made a substantial contribution to crosslinking curing.

[0053] Comparing Example 1 with Comparative Example 3, it can be seen that Comparative Example 3 significantly increased the radiation energy of the cold light source during the initial curing of the primer in step S4, and simultaneously activated far-infrared heating. The results showed that the delamination and cracking rate of the primer layer in Comparative Example 3 increased sharply to 18.5%, the abrasive loss volume rose to 12.4%, and the grinding efficiency retention rate after 150 hours of grinding was only 42.0%. This is because excessive initial curing caused the cationic reactive sites and reaction space deep within the primer layer to be prematurely consumed during the initial curing process, resulting in premature loss of matrix toughness. By step S6, during the main curing, even with far-infrared thermal catalysis, there were no longer any active centers in the abrasive shadow area for the dark reaction to extend. This prematurely blocked the "dark reaction extension channel" that this invention relies on to overcome deep light shielding, leading to stress cracking and delamination within the primer layer under heavy load and strong shear. This strongly confirms the decisive role of the precise initial curing strategy adopted in step S4: "surface network cross-locking, maintaining semi-cured lower layer and retaining deep activity."

[0054] Comparing Example 1 with Comparative Example 4, it can be seen that Comparative Example 4 omits the interlayer reinforcement functional primer and pre-curing treatment in step S1, and directly applies the primer to the original fabric substrate surface. Test data shows that after 150 hours of wet sanding, the delamination and cracking rate of the adhesive layer reached 26.0%, and the sand loss volume reached 18.2%. In the later stages of sanding, the adhesive layer peeled off completely from the fabric substrate surface. This fully demonstrates that the interlayer reinforcement functional primer liquid, by specifically introducing a phosphoric acid esterified acrylate adhesion promoter and forming an "active anchoring layer with unreacted active polar groups" through low-energy ultraviolet radiation, can form a very strong chemical bonding interface with the free radical-cationic hybrid primer in step S2. Once this active anchoring layer is missing, the interlayer bonding relies solely on the physical wetting of the fabric substrate by the primer. Under the combined effect of strong shear force and water swelling stress of heavy-load continuous wet sanding, the interface between the substrate and the adhesive layer is extremely prone to catastrophic peeling.

[0055] Comparing Example 1 with Comparative Example 5: Comparative Example 5 simultaneously abandoned the two core technologies of this invention, namely the "free radical-cationic hybrid system" and the "primary curing far-infrared thermal synergy" (dual-deficient control group). Test results showed that Comparative Example 5 had a delamination and cracking rate as high as 46.2%, a sanding volume loss of 31.5%, and a grinding efficiency retention rate of only 15.0%. All grinding performance indicators were the worst among all test groups, and the abrasive belt completely failed in the early stages of the test. This result profoundly confirms, from the opposite perspective, the extreme shielding and absorption effect of the opaque solid abrasive layer on light. Without cationic components for spontaneous diffusion in the dark reaction, and without the thermal energy to promote molecular chain flexibility and chromic acid migration, the bottom adhesive of the abrasive belt remained completely uncured, thoroughly exposing the limitations of conventional photocuring systems in the field of heavy-duty abrasive manufacturing.

[0056] The results of Comparative Examples 1 to 5 further reveal a clear hierarchy in the failure mechanisms and severity of each control group: Double-deficient group (Comparative Example 5) -> Pure free radical group (Comparative Example 1) -> Group lacking active anchoring layer (Comparative Example 4) -> Group lacking thermal catalyst (Comparative Example 2) -> Over-curing group (Comparative Example 3). This hierarchical data chain clearly demonstrates that the free radical-cation hybrid system provides the fundamental "curing capability" for deep curing, the stepped photo-thermal synergistic energy field determines the "sufficiency" of deep dark reaction crosslinking, and the surface semi-curing locking strategy and interlayer active primer provide decisive and precise guarantees for the construction of high-strength networks in the "time dimension" and "spatial interface," respectively. All these technical means work together in close coordination, each indispensable, to achieve the near-zero delamination, extremely low sand shedding, and high grinding efficiency retention of the industrial-grade comprehensive grinding performance in each embodiment.

[0057] Based on the experimental results above, and as shown in Table 1, the quantitative test results indicate that after 150 hours of continuous grinding under heavy-load conditions of belt drive linear speed of 28 m / s, contact impact load pressure of 0.4 MPa, and continuous water-cooled wet grinding, the photocured abrasive belts prepared in Examples 1 to 8 all exhibited adhesive layer delamination and cracking rates controlled within the range of 0-0.3%, abrasive drop (abrasive shedding) volume percentage not exceeding 1.2%, and grinding efficiency retention rates reaching over 81.5% of the initial efficiency, with a maximum of 91.2%. These results are consistently valid across a wide range of abrasive types (including silicon carbide, white corundum, brown corundum, and microcrystalline ceramic corundum), abrasive particle sizes (ranging from P60 to P600), and application conditions (from heavy-load coarse grinding to fine polishing). This demonstrates that the preparation method of this invention has good universality for different abrasive systems and processing conditions, and excellent process reproducibility.

[0058] Further analysis of the inherent patterns in each embodiment reveals that the coarser the abrasive grain size and the heavier the grinding load, the higher the requirement for the deep cross-linking strength of the primer. Taking Example 7, which uses P60 coarse-grained brown fused alumina for heavy-duty high-cutting applications, as an example, its delamination cracking rate (0.3%) and abrasive loss volume (1.2%) are relatively the highest among all embodiments, while its grinding efficiency retention rate (81.5%) is relatively the lowest. In contrast, Example 8, which uses P600 ultra-fine polycrystalline white fused alumina for fine polishing of automotive paint, has a delamination cracking rate of 0%, an abrasive loss volume of only 0.3%, and a grinding efficiency retention rate as high as 91.2%. Even under the conditions of heavy-duty rough grinding with the thickest coating and the most severe shearing (Example 7), the delamination cracking rate of the abrasive belt does not exceed 0.3%, indicating that the stepped photothermal synergistic deep curing mechanism of the present invention can still achieve high-strength full cross-linking at the bottom of the abrasive layer even under the most stringent heavy-duty conditions. The overall manufacturing energy consumption of each embodiment ranges from 11.5 to 17.2 kWh / 100 square meters, and is positively correlated with coating thickness and main curing energy—Example 7, with the thickest coating and the highest main curing energy, has the highest energy consumption (17.2 kWh), while Example 8, with the thinnest coating, has the lowest energy consumption (11.5 kWh)—the data are consistent with each other. Compared to traditional thermosetting phenolic abrasive belts, which require several hours of high-temperature wire baking and have manufacturing energy consumption of up to hundreds of kilowatt-hours, the manufacturing energy consumption of this invention is significantly reduced, and there is no emission of free formaldehyde or volatile organic compounds throughout the entire process.

[0059] Comparing Example 1 with Comparative Example 1: Comparative Example 1 was identical to Example 1 except that the base adhesive in step S2 and the top adhesive in step S5 were changed from a free radical-cationic hybrid system to a conventional pure free radical all-acrylate system. The results showed that Comparative Example 1 exhibited a delamination and cracking rate as high as 38.5%, a sand loss volume of 24.6%, and a grinding efficiency retention rate that plummeted to 22.3%. Furthermore, it failed due to large-area delamination and tearing within less than 20 hours of grinding. This is because the curing of the pure free radical system relies entirely on the excitation of direct ultraviolet photons. The opaque inorganic abrasive, after sand deposition, blocked the lower layer of photons, preventing the bottom base adhesive in the shadow zone from curing, leading to catastrophic failure under heavy shear load. Therefore, the cationic component introduced by the free radical-cationic hybrid system in the base adhesive, and its dark reaction characteristics—which allow it to spontaneously extend and cross-link deeper even after the light source is removed—are key to overcoming deep light shielding in opaque abrasive layers and achieving deep curing strength.

[0060] Comparing Example 1 with Comparative Example 2: Comparative Example 2 also used a free radical-cationic hybrid resin system, and the total input light energy was the same as in Example 1 (both were 1800 mJ / cm). 2The only difference is that the far-infrared heating plate was turned off during the main curing step S6, and the sample was irradiated in one direction by a high-pressure mercury lamp at room temperature. The results showed that Comparative Example 2 had a delamination and cracking rate of 14.2%, a sand loss volume of 9.8%, and a grinding efficiency retention rate of 48.0%, which was significantly better than Comparative Example 1 with pure free radicals, but still far from the levels of the various embodiments. This is because, in the absence of far-infrared thermal energy, the diffusion and migration rate of the active centers of cationic protonic acids is extremely slow. Within the limited curing time, only localized weak cross-linking can occur in the shaded area, and deep full cross-linking cannot be fully completed. Therefore, the decisive condition for transforming the "deep curing potential" endowed by the hybrid system into "deep full cross-linking performance" is the synergistic effect of far-infrared thermal energy and high-energy ultraviolet light, which increases the flexibility of the resin matrix molecular chain segments, thereby causing a geometric leap in the diffusion rate of protonic acids.

[0061] The results of Comparative Example 1 and Comparative Example 2 further reveal a clear hierarchy in their failure rates: Comparative Example 1, lacking the cationic component (delamination and cracking rate of 38.5%), is inferior to Comparative Example 2, lacking only thermal synergy (delamination and cracking rate of 14.2%). This indicates that the free radical-cationic hybrid system provides the fundamental "curing capability" for deep curing, while the stepped photo-thermal synergistic energy field determines the "sufficiency" of deep curing. Both are indispensable and work together to achieve the comprehensive performance of near-zero delamination, low abrasive shedding, and high grinding efficiency retention in each embodiment. This invention achieves long-life grinding performance for industrial-grade heavy-duty abrasive belts by deeply combining the free radical-cationic hybrid photocurable resin system with the stepped photo-thermal synergistic energy field, while retaining the advantages of high efficiency, low energy consumption, and zero volatile organic compound emissions from photocuring, overcoming the deep-layer uncuring defects caused by the light shielding of the opaque abrasive layer.

[0062] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a light-cured abrasive belt, characterized in that, Includes the following steps: S1. Provide the original abrasive belt fabric base, and apply an enhanced functional primer between the roller coatings on the working surface of the original abrasive belt fabric base. Pre-cur the primer under ultraviolet light to form an active anchoring layer with unreacted active polar groups, thus obtaining a pre-treated fabric base. S2. A photocurable primer is coated onto the surface of the active anchoring layer of the pretreated fabric to form a photocurable primer layer. The photocurable primer is a free radical-cationic hybrid photocurable system, and the coating amount is 60~130 g / m². 2 ; S3. Under a high-voltage electrostatic field, inorganic abrasives are oriented and vertically implanted into the uncured photocurable base layer to form an oriented abrasive layer; S4. The substrate after sand planting is sent into the No. 1 curing box and cold light source radiation is used for initial curing to make the surface of the photocurable base layer cross network locking and lock the root of the inorganic abrasive in situ, and keep the lower layer of the photocurable base layer in a semi-cured state, retaining the reactivity of the cationic components therein. S5. Apply a light-cured adhesive to the surface of the initially cured oriented abrasive layer, with a coating amount of 50~110 g / m². 2 ; S6. The substrate after coating with adhesive is sent into the second curing chamber. First, the surface of the photocurable adhesive is irradiated by the second ultraviolet light source. Then, the substrate is irradiated and heated by a stepped energy field that combines ultraviolet light irradiation and infrared thermal radiation, which triggers the cationic dark reaction in the deep layer of the photocurable base adhesive, causing the deep base adhesive that is blocked by the inorganic abrasive to crosslink and cure. After curing, the substrate is mechanically softened, cut into strips, and joined together to obtain the photocurable abrasive belt.

2. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S1, the original fabric base of the sanding belt is a Ywt or Xwt grade all-polyester waterproof fabric base; the interlayer reinforcing functional primer is composed of the following raw materials in parts by weight: 60 parts of polyurethane acrylate oligomer, 15 parts of phosphoric acid esterified acrylate adhesion promoter, 20 parts of reactive diluent monomer, and 5 parts of free radical photoinitiator; the coating amount of the interlayer reinforcing functional primer is 15~30 g / m². 2 .

3. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S2, the free radical-cationic hybrid photocuring system is composed of the following raw materials in parts by weight: 35-48 parts of alicyclic epoxy resin, 28-40 parts of hydroxyl-terminated modified polyurethane acrylate, 8-15 parts of polyol, 10 parts of isobornyl acrylate, 3 parts of sulfonium salt cationic photoinitiator, and 2 parts of free radical photoinitiator.

4. The method for preparing photocurable abrasive belt according to claim 3, characterized in that, The sulfonium salt cationic photoinitiator is a triarylsulfonium salt photoinitiator, the free radical photoinitiator is an α-hydroxy ketone photoinitiator, and the polyol is polytetrahydrofuran diol.

5. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S3, the inorganic abrasive is one or more of silicon carbide, white corundum, brown corundum, and microcrystalline ceramic abrasive, and the particle size of the inorganic abrasive is P60~P600 mesh; the process parameters of the electrostatic sand planting are: high voltage electrostatic field voltage of 30~55 kV, and electrode spacing of 80~130 mm.

6. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S4, the first ultraviolet light source is an LED-UV cold light source with a central radiation wavelength of 365 nm or 395 nm and a radiation energy density of 150~350 mJ / cm². 2 .

7. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S5, the photocurable adhesive is composed of hyperbranched polyurethane acrylate oligomer, nano-silica modified acrylate resin, silane coupling agent grafted abrasive additive and composite photoinitiator, with a solid content of 100%.

8. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S6, the second curing chamber is equipped with a UV-LED array lamp group, a high-pressure and medium-pressure mercury lamp group, and a far-infrared heating plate; the irradiation process of the stepped energy field is as follows: first, the UV-LED array lamp group with a wavelength of 395 nm is used at 400~600 mJ / cm 2 The energy initiates the surface drying of the photocurable adhesive, and then the high-pressure mercury lamp assembly applies 1200~2500 mJ / cm². 2 The full spectrum of energy is radiated, and the far-infrared heating plate is turned on simultaneously to keep the local substrate temperature of the photocurable base layer at 80~110 ℃ for 1~3 minutes.

9. The method for preparing photocurable abrasive belt according to claim 1, characterized in that, In step S6, the mechanical softening is: the cured abrasive belt is repeatedly stretched and bent in different directions by a 90-degree and 180-degree roller bending softening machine.

10. A light-cured sanding belt, characterized in that, The photocurable abrasive belt is prepared by the method described in any one of claims 1 to 9.

Images