Flexible phenol resin-based abrasive paper and low-temperature curing coating process thereof

Abstract

The application discloses a flexible phenolic resin-based abrasive paper and a low-temperature curing gluing process thereof, and relates to the technical field of abrasive paper. The flexible phenolic resin-based abrasive paper comprises a base material and a glue layer, the glue layer comprises an adhesive and an abrasive dispersed in the adhesive. The adhesive adheres the abrasive and the base material and is cured on the base material. Raw materials for preparing the adhesive comprise the following components in mass parts: phenolic resin 50-70 parts, toughening agent 10-20 parts, curing agent 5-15 parts, and inorganic filler 5-15 parts; the curing agent is 3-amino-4-methoxybenzenesulfonic acid. The 3-amino-4-methoxybenzenesulfonic acid has mild curing conditions for phenolic resin and can be used for low-temperature curing below 90 DEG C. The low-temperature curing process can slow down the curing reaction rate, so that the phenolic resin molecules have more time for arrangement and recombination, thereby reducing the internal stress of the cured product. The improved curing agent and the low-temperature curing process improve the flexibility of the glue layer.

Description

Technical Field

[0001] This application relates to the field of sandpaper technology, and in particular to a sandpaper based on flexible phenolic resin and its low-temperature curing coating process. Background Technology

[0002] In the sandpaper manufacturing industry, phenolic resin is widely used as an adhesive for the adhesive layer, primarily because it meets the requirements of sandpaper for high strength, heat resistance, and abrasion resistance. After curing, phenolic resin forms a three-dimensional network structure, providing extremely high bonding strength and firmly fixing abrasive particles to various substrate materials. Phenolic resin has a heat resistance temperature of 200-250℃, and even at temperatures exceeding 150℃ generated by high-speed sanding, it maintains its structure without softening or decomposition. The cured phenolic resin has high hardness, resisting the reverse abrasion of abrasive particles and preventing premature wear of the adhesive layer. However, phenolic resin also suffers from poor flexibility; during sanding, bending can easily cause cracks or severe creases, leading to powder shedding and reducing the lifespan of the sandpaper.

[0003] Currently, phenolic resin is used as the adhesive layer in sandpaper production. Commonly used curing agents include acidic and alkaline curing agents. Acidic curing agents, such as hydrochloric acid, cure phenolic resin too quickly, causing excessive cross-linking and resulting in brittleness and poor adhesive layer flexibility. Alkaline curing agents, such as hexamethylenetetramine, require high-temperature treatment above 150°C, which can easily lead to adhesive layer embrittlement and poor flexibility. When sanding objects with sandpaper that has poor adhesive layer flexibility, the adhesive layer is prone to cracking or severe creases due to bending, causing powder to fall off, which reduces the lifespan of the sandpaper. Summary of the Invention

[0004] To address the issue of poor flexibility in the adhesive layer of sandpaper produced by some current processes for curing phenolic resins, this application proposes a sandpaper based on flexible phenolic resin and its low-temperature curing adhesive coating process to solve this problem.

[0005] In the first aspect, this application proposes a sandpaper based on flexible phenolic resin, and adopts the following technical solution.

[0006] A type of sandpaper based on flexible phenolic resin, the sandpaper comprising a substrate and an adhesive layer, the adhesive layer comprising an adhesive and abrasive particles dispersed in the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate. The raw materials for preparing the adhesive comprise the following components in parts by weight: 50-70 parts phenolic resin, 10-20 parts toughening agent, 5-15 parts curing agent, and 5-15 parts inorganic filler; the curing agent is 3-amino-4-methoxybenzenesulfonic acid.

[0007] By employing the above technical solution, 3-amino-4-methoxybenzenesulfonic acid can provide protonated hydrogen to protonate the hydroxymethyl group of a phenolic resin. The protonated hydroxymethyl group then reacts with another hydroxymethyl group or a hydrogen atom on the benzene ring of the phenolic resin in a dehydration condensation reaction. This reaction proceeds fully, allowing the phenolic resin to cure. The curing conditions for phenolic resin with 3-amino-4-methoxybenzenesulfonic acid are mild, allowing for low-temperature curing below 90°C. This slows down the curing reaction rate, giving the phenolic resin molecules more time to arrange and recombine, thereby reducing internal stress in the cured product and improving its toughness. This improved curing agent, combined with a low-temperature curing process, enhances the flexibility of the adhesive layer. Toughening agents reduce the brittleness of the adhesive layer and improve impact strength and fracture toughness. Inorganic fillers improve the strength and toughness of the adhesive layer.

[0008] A preferred embodiment of the flexible phenolic resin-based sandpaper is that the raw materials for preparing the adhesive further include the following components in parts by weight: 0.5-3 parts of antioxidant di-tert-butyl-p-cresol and 0.5-2 parts of stabilizer calcium stearate.

[0009] By employing the above technical solution, di-tert-butyl-p-cresol can provide hydrogen atoms to capture free radicals, block oxidation chain reactions, and exert an antioxidant effect. Calcium stearate can absorb free acids, delay thermal degradation, and improve the thermal stability of the adhesive.

[0010] In a preferred embodiment of the flexible phenolic resin-based sandpaper, the inorganic filler is montmorillonite and / or calcium carbonate, and the particle size of the inorganic filler is less than 100 nm.

[0011] By adopting the above technical solution, montmorillonite and / or calcium carbonate adjust the viscosity of the adhesive, which can disperse the stress of phenolic resin, form a reinforced structure, improve the strength and toughness of the adhesive layer, and prevent the propagation of cracks.

[0012] In a preferred embodiment of the flexible phenolic resin-based sandpaper, the toughening agent is nitrile rubber, diethyl phthalate, or leaf ester of isovalerate.

[0013] By employing the above technical solutions, nitrile rubber can form tiny rubber particles within phenolic resin, absorbing impact energy and preventing crack propagation. Both diethyl phthalate and leaf ester of isovalerate, based on their polar and non-polar groups, can insert themselves between phenolic resin molecular chains, increasing intermolecular distance, reducing interchain entanglement, and enhancing chain segment mobility. Leaf ester of isovalerate exhibits a stronger insertion effect between phenolic resin molecular chains, resulting in a more pronounced toughening effect.

[0014] A preferred embodiment of the sandpaper based on flexible phenolic resin is that the abrasive is silicon carbide particles and / or alumina particles with a particle size of 10~50μm.

[0015] By adopting the above technical solution, silicon carbide particles and alumina particles have high hardness, and particles of this size can be used to polish the surface of an object to achieve a smooth finish. The mass ratio of silicon carbide particles to alumina particles can be any, for example (1-2):(1-2), but is not limited to this. The mass ratio of the raw materials for abrasive and binder can be (2-5):1, but is not limited to this.

[0016] In a preferred embodiment of the sandpaper based on flexible phenolic resin, the substrate is a polyester fiber cloth.

[0017] By adopting the above technical solution, sandpaper has a substrate with good flexibility.

[0018] Secondly, this application also proposes a low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin, and adopts the following technical solution.

[0019] A low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin, as described above, involves adding the raw materials for preparing the adhesive to a solvent according to the proportions of each component, dispersing them evenly, first performing a prepolymer reaction at a temperature of 40-50°C for 1-2 hours to form a prepolymer, then adding the abrasive and mixing it evenly to obtain a mixture, then uniformly coating the mixture onto a substrate to form a uniform adhesive layer, and finally curing it at a low temperature of 80-90°C for 2-4 hours.

[0020] By employing the above technical solution, in the low-temperature prepolymerization stage at 40-50℃, the curing agent, plasticizer, inorganic filler, and phenolic resin are dispersed in a solvent. The diluted curing agent protonates the hydroxymethyl group of one phenolic resin. This protonated hydroxymethyl group reacts with another hydroxymethyl group or hydrogen on the benzene ring of the phenolic resin to undergo dehydration condensation. Due to the diluted concentration and low reaction temperature, this reaction proceeds in small amounts to form a preliminary cross-linked structure, i.e., a prepolymer. Finally, a low-temperature curing process at 80-90℃ is performed, during which the solvent evaporates. The slower curing reaction of the prepolymer allows more time for the phenolic resin molecules to arrange and recombine, thereby reducing the internal stress of the cured product, improving its toughness, and saving energy. The sufficiently long reaction time allows the hydroxymethyl dehydration condensation reaction to proceed fully, forming a three-dimensional network structure. The adhesive layer possesses both good toughness and wear resistance. The optimal ambient humidity during the curing process is 40-60%RH to ensure uniform curing. The evaporated solvent is also recovered and cooled during the curing process for use in the next dissolution or dispersion of the curing agent, plasticizer, inorganic filler, and phenolic resin.

[0021] A preferred embodiment of the low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin is that the solvent is a mixture of ethanol and acetone in a volume ratio of (1~2):3; the ratio of the mass of the adhesive raw material to the volume of the solvent is 1g / (15~20)mL.

[0022] By adopting the above technical solution, this ratio of ethanol and acetone can fully dissolve phenolic resin, curing agent, and plasticizer, which is beneficial for prepolymerization reaction.

[0023] In summary, the sandpaper based on flexible phenolic resin and its low-temperature curing coating process of this application have the following beneficial effects: using phenolic resin as the adhesive and selecting 3-amino-4-methoxybenzenesulfonic acid as the curing agent reduces the curing temperature and improves the flexibility of the cured phenolic resin; by selecting toughening agents and inorganic fillers, the toughness of the adhesive layer is further enhanced; and by selecting antioxidants and stabilizers, the antioxidant properties and thermal stability of the adhesive layer are improved. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the sandpaper low-temperature curing adhesive coating process of this application. Detailed Implementation

[0025] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Example 1

[0026] refer to Figure 1 The low-temperature curing coating process for sandpaper based on flexible phenolic resin has the following steps.

[0027] Using nitrile rubber as a toughening agent, 3-amino-4-methoxybenzenesulfonic acid as a curing agent, and calcium carbonate as an inorganic filler with a particle size of less than 100 nm, 60 parts by mass of phenolic resin, 15 parts by mass of toughening agent, 10 parts by mass of curing agent, and 10 parts by mass of inorganic filler were taken as raw materials for preparing the adhesive. The raw materials were placed in a solvent of ethanol and acetone mixed in a volume ratio of 1.5:3, and the ratio of the mass of the raw materials to the volume of the solvent was 1 g / 20 mL to obtain the reaction solution.

[0028] In an environment with 50% RH, the reaction solution was stirred evenly using a high-speed mixer at 1000 rpm. The mixture was then prepolymerized at 45°C for 1.5 hours to form a prepolymer. Abrasive particles (a 1:1 mass ratio of silicon carbide to alumina, with a particle size of 10-50 μm) were then added. The mass ratio of abrasive to binder was 3:1. The abrasive and prepolymer were mixed evenly to obtain a binder. This binder was then uniformly coated onto a substrate with a thickness of 0.3 mm and a basis weight of 200 g / m². 2A uniform adhesive layer is formed on a polyester fiber fabric substrate, and then cured at a low temperature of 85°C for 3 hours. After cooling, the sandpaper is obtained. The substrate is cleaned and plasma-treated before adhesive application to improve surface adhesion. The cured adhesive layer is 0.2 mm thick. The cured adhesive layer includes the adhesive itself and abrasive particles dispersed within the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate. Example 2

[0029] This embodiment provides a low-temperature curing coating process for sandpaper based on flexible phenolic resin. Compared with Embodiment 1, this embodiment only changes the type of toughening agent, specifically replacing nitrile rubber with diethyl phthalate, and finally preparing sandpaper. Example 3

[0030] This embodiment provides a low-temperature curing coating process for sandpaper based on flexible phenolic resin. Compared with Embodiment 1, this embodiment only changes the type of toughening agent, specifically replacing nitrile rubber with isovaleric acid leaf ester, and finally preparing sandpaper. Example 4

[0031] This embodiment provides a low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin. Compared with Embodiment 1, this embodiment changes various parameters and adds the following component by mass to the raw materials for preparing the adhesive: 0.5 parts of antioxidant di-tert-butyl-p-cresol, and finally prepares the sandpaper.

[0032] The low-temperature curing coating process for sandpaper based on flexible phenolic resin consists of the following steps.

[0033] Using nitrile rubber as a toughening agent, 3-amino-4-methoxybenzenesulfonic acid as a curing agent, montmorillonite as an inorganic filler with a particle size of less than 100 nm, and di-tert-butyl-p-cresol as an antioxidant, 50 parts by mass of phenolic resin, 20 parts by toughening agent, 5 parts by curing agent, 15 parts by inorganic filler, and 0.5 parts by antioxidant were taken as raw materials for preparing the adhesive. The raw materials were placed in a solvent of ethanol and acetone mixed in a volume ratio of 1:3, and the ratio of the mass of the raw materials to the volume of the solvent was 1 g / 20 mL to obtain the reaction solution.

[0034] In an environment with 50% RH, the reaction solution was stirred evenly using a high-speed mixer at 1000 rpm. The mixture was then prepolymerized at 40°C for 2 hours to form a prepolymer. Abrasive particles (a 1:1 mass ratio of silicon carbide to alumina, with a particle size of 10-50 μm) were then added. The mass ratio of abrasive to binder was 3:1. The abrasive and prepolymer were mixed evenly to obtain a binder. This binder was then uniformly coated onto a substrate with a thickness of 0.3 mm and a basis weight of 200 g / m². 2A uniform adhesive layer is formed on a polyester fiber fabric substrate, and then cured at a low temperature of 80°C for 4 hours. After cooling, the sandpaper is obtained. The substrate is cleaned and plasma-treated before adhesive application to improve surface adhesion. The cured adhesive layer is 0.2 mm thick. The cured adhesive layer includes the adhesive itself and abrasive particles dispersed within the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate. Example 5

[0035] This embodiment provides a low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin. Compared with Embodiment 1, this embodiment changes various parameters and adds the following component by mass to the raw materials for preparing the adhesive: 0.5 parts of calcium stearate stabilizer, and finally prepares the sandpaper.

[0036] The low-temperature curing coating process for sandpaper based on flexible phenolic resin consists of the following steps.

[0037] Using nitrile rubber as a toughening agent, 3-amino-4-methoxybenzenesulfonic acid as a curing agent, calcium carbonate as an inorganic filler with a particle size of less than 100 nm, and calcium stearate as a stabilizer, 70 parts by mass of phenolic resin, 10 parts by mass of toughening agent, 15 parts by mass of curing agent, 5 parts by mass of inorganic filler, and 0.5 parts by mass of stabilizer were taken as raw materials for preparing the adhesive. The raw materials were placed in a solvent of ethanol and acetone mixed in a volume ratio of 2:3, and the ratio of the mass of the raw materials to the volume of the solvent was 1 g / 15 mL to obtain the reaction solution.

[0038] In an environment with 50% RH, the reaction solution was stirred evenly using a high-speed mixer at 1000 rpm. The mixture was then prepolymerized at 50°C for 1 hour to form a prepolymer. Abrasive particles (a 1:1 mass ratio of silicon carbide to alumina, with a particle size of 10-50 μm) were then added. The mass ratio of abrasive to binder was 3:1. The abrasive and prepolymer were mixed evenly to obtain a binder. This binder was then uniformly coated onto a substrate with a thickness of 0.3 mm and a basis weight of 200 g / m². 2 A uniform adhesive layer is formed on a polyester fiber fabric substrate, and then cured at a low temperature of 90°C for 2 hours. After cooling, the sandpaper is obtained. The substrate is cleaned and plasma-treated before adhesive application to improve surface adhesion. The cured adhesive layer is 0.2 mm thick. The cured adhesive layer includes the adhesive itself and abrasive particles dispersed within the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate. Example 6

[0039] This embodiment provides a low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin. Compared with Embodiment 1, this embodiment changes various parameters and adds the following components by mass to the raw materials for preparing the adhesive: 3 parts of antioxidant di-tert-butyl-p-cresol and 2 parts of stabilizer calcium stearate, and finally prepares the sandpaper.

[0040] The low-temperature curing coating process for sandpaper based on flexible phenolic resin consists of the following steps.

[0041] Using nitrile rubber as a toughening agent, 3-amino-4-methoxybenzenesulfonic acid as a curing agent, and montmorillonite and calcium carbonate as inorganic fillers with a particle size of less than 100 nm, 60 parts by mass of phenolic resin, 15 parts by mass of toughening agent, 10 parts by mass of curing agent, 5 parts by mass of montmorillonite, 5 parts by mass of calcium carbonate, 3 parts by mass of antioxidant di-tert-butyl-p-cresol, and 2 parts by mass of stabilizer calcium stearate were used as raw materials for preparing the adhesive. The raw materials were placed in a solvent of ethanol and acetone mixed in a volume ratio of 1.5:3, and the ratio of the mass of the raw materials to the volume of the solvent was 1 g / 20 mL to obtain the reaction solution.

[0042] In an environment with 50% RH, the reaction solution was stirred evenly using a high-speed mixer at 1000 rpm. The mixture was then prepolymerized at 45°C for 1.5 hours to form a prepolymer. Abrasive particles (a 1:1 mass ratio of silicon carbide to alumina, with a particle size of 10-50 μm) were then added. The mass ratio of abrasive to binder was 3:1. The abrasive and prepolymer were mixed evenly to obtain a binder. This binder was then uniformly coated onto a substrate with a thickness of 0.3 mm and a basis weight of 200 g / m². 2 A uniform adhesive layer is formed on a polyester fiber fabric substrate, and then cured at a low temperature of 85°C for 3 hours. After cooling, the sandpaper is obtained. The substrate is cleaned and plasma-treated before adhesive application to improve surface adhesion. The cured adhesive layer is 0.2 mm thick. The cured adhesive layer includes the adhesive itself and abrasive particles dispersed within the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate.

[0043] Comparative Example 1 This comparative example provides a low-temperature curing coating process for sandpaper based on flexible phenolic resin. Compared with Example 1, the curing agent is replaced by benzenesulfonic acid instead of 3-amino-4-methoxybenzenesulfonic acid, while other conditions remain the same, and sandpaper is finally prepared.

[0044] Comparative Example 2 This comparative example provides a low-temperature curing coating process for sandpaper based on flexible phenolic resin. Compared with Example 1, the curing agent is replaced by hexamethylenetetramine instead of 3-amino-4-methoxybenzenesulfonic acid, and the curing temperature is increased. The specific steps are as follows.

[0045] Using nitrile rubber as a toughening agent, hexamethylenetetramine as a curing agent, and calcium carbonate as an inorganic filler with a particle size of less than 100 nm, 60 parts by mass of phenolic resin, 15 parts by mass of toughening agent, 10 parts by mass of curing agent, and 10 parts by mass of inorganic filler were taken as raw materials for preparing the adhesive. The raw materials were placed in a solvent of ethanol and acetone mixed in a volume ratio of 1.5:3, and the ratio of the mass of the raw materials to the volume of the solvent was 1 g / 20 mL to obtain the reaction solution.

[0046] In an environment with 50% RH, the reaction solution was stirred evenly using a high-speed mixer at 1000 rpm. The mixture was then prepolymerized at 45°C for 1.5 hours to form a prepolymer. Abrasive particles (a 1:1 mass ratio of silicon carbide to alumina, with a particle size of 10-50 μm) were then added. The mass ratio of abrasive to binder was 3:1. The abrasive and prepolymer were mixed evenly to obtain a binder. This binder was then uniformly coated onto a substrate with a thickness of 0.3 mm and a basis weight of 200 g / m². 2 A uniform adhesive layer is formed on a polyester fiber fabric substrate, and then cured at 150°C for 1 hour. After cooling, the sandpaper is obtained. The substrate is cleaned and plasma-treated before adhesive application to improve surface adhesion. The cured adhesive layer is 0.2 mm thick. The cured adhesive layer includes the adhesive itself and abrasive particles dispersed within the adhesive. The adhesive adheres the abrasive particles to the substrate and cures on the substrate.

[0047] Experimental Example 1 The sandpaper prepared in Examples 1-6 and Comparative Examples 1-2 were tested as follows.

[0048] Adhesion test: The adhesive layer on the sandpaper is divided into grids using the cross-cut method. The adhesion of the adhesive layer is indicated by the proportion of the area that has peeled off in the grid area.

[0049] Dust test: In a closed environment, the same copper plate was used as the test object and sanded with sandpaper until the surface roughness of the copper plate reached Ra0.8. The dust generated during the sanding process was collected and weighed.

[0050] Flexibility test: Cut sandpaper into 10cm×10cm samples and perform a 180° bending test at the same position, recording the number of times it takes to bend to reach the same degree of crease.

[0051] The results of the above three tests are shown in Table 1 below.

[0052] Table 1. Test data on adhesive adhesion, sanding dust, and flexibility of sandpaper. Example 1 4% 0.16g 45 Example 2 6% 0.18g 40 Example 3 2% 0.05g 60 Example 4 4% 0.20g 43 Example 5 5% 0.17g 42 Example 6 6% 0.19g 40 Comparative Example 1 10% 0.25g 30 Comparative Example 2 20% 0.34g 20 Table 1 shows that the peeling area of ​​the sandpaper after scribbling in Examples 1-6 is less than 6%, while the peeling area of ​​the sandpaper in Comparative Example 1 is 10% and that of the sandpaper in Comparative Example 2 is 20%. This indicates that the low-temperature curing scheme of Examples 1-6 using 3-amino-4-methoxybenzenesulfonic acid as a curing agent has better adhesive layer adhesion than the low-temperature curing scheme of Comparative Example 1 using benzenesulfonic acid as a curing agent, and is even better than the scheme of Comparative Example 2 using hexamethylenetetramine as a curing agent and using a high-temperature curing temperature of 150°C.

[0053] The amount of dust generated by sanding with sandpaper in Examples 1-6 is lower than that generated by sanding with sandpaper in Comparative Examples 1-2, indicating that using sandpaper prepared in Examples 1-6 to sand items can significantly reduce dust pollution, especially the sanding method in Example 3, which has the most significant dust reduction effect.

[0054] The sandpapers of Examples 1-6 formed more creases of the same degree when bent at 180° than the sandpapers of Comparative Examples 1-2, indicating that the sandpapers of Examples 1-6 have better flexibility. Since the base layer is the same, the adhesive layer of the sandpapers of Examples 1-6, especially the adhesive layer of the sandpapers of Example 3, has better flexibility.

[0055] This application uses 3-amino-4-methoxybenzenesulfonic acid as a curing agent and further toughens and modifies phenolic resin with toughening agents and inorganic fillers. After the components are mixed, dissolved or dispersed, they are first prepolymerized at a low temperature of 40-50℃. The components are then dispersed and the phenolic resin is initially cured. After the colloid is coated on the substrate, it is then cured at a low temperature of 80-90℃. The resulting adhesive layer has strong adhesion to the substrate, good flexibility, and produces less powder when sanded. Compared with some high-temperature curing schemes of 150℃, it significantly improves flexibility.

[0056] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A type of sandpaper based on flexible phenolic resin, characterized in that, The sandpaper includes a substrate and an adhesive layer, the adhesive layer including an adhesive and abrasive particles dispersed in the adhesive; the adhesive adheres the abrasive particles and the substrate, and cures on the substrate; The raw materials for preparing the adhesive include the following components in parts by weight: 50-70 parts of phenolic resin, 10-20 parts of toughening agent, 5-15 parts of curing agent, and 5-15 parts of inorganic filler; wherein the curing agent is 3-amino-4-methoxybenzenesulfonic acid.

2. The sandpaper based on flexible phenolic resin according to claim 1, characterized in that, The raw materials for preparing the adhesive also include the following components in parts by weight: 0.5-3 parts of antioxidant di-tert-butyl-p-cresol and 0.5-2 parts of stabilizer calcium stearate.

3. The sandpaper based on flexible phenolic resin according to claim 1, characterized in that, The inorganic filler is montmorillonite and / or calcium carbonate, and the particle size of the inorganic filler is less than 100 nm.

4. The sandpaper based on flexible phenolic resin according to claim 1, characterized in that, The toughening agent is nitrile rubber, diethyl phthalate, or leaf ester of isovalerate.

5. The sandpaper based on flexible phenolic resin according to claim 1, characterized in that, The abrasive is silicon carbide particles and / or alumina particles with a particle size of 10~50μm.

6. The sandpaper based on flexible phenolic resin according to claim 1, characterized in that, The substrate is polyester fiber cloth.

7. A low-temperature curing adhesive coating process for sandpaper based on flexible phenolic resin as described in any one of claims 1-6, characterized in that, According to the proportions of each component, the raw materials for preparing the adhesive are added to the solvent and dispersed evenly. First, a prepolymer reaction is carried out at a temperature of 40-50℃ for 1-2 hours to form a prepolymer. Then, the abrasive is added and mixed evenly to obtain a mixture. The mixture is then evenly coated on the substrate to form a uniform adhesive layer. Finally, it is cured at a low temperature of 80-90℃ for 2-4 hours.

8. The low-temperature curing coating process for sandpaper based on flexible phenolic resin according to claim 7, characterized in that, The solvent is a mixture of ethanol and acetone in a volume ratio of (1~2):3; the ratio of the mass of the raw material of the adhesive to the volume of the solvent is 1 g / (15~20) mL.

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