A rapid hot-pressed thin phenolic resin laminated board and a preparation method thereof

Abstract

This invention discloses a rapid hot-pressing thin phenolic resin laminate and its preparation method, relating to the technical field of phenolic resin laminates. The preparation method includes the following steps: adding formaldehyde and phenol to a container, stirring evenly, adjusting the pH of the reaction system, heating, vacuum dehydration, heat preservation, adding urea, stirring evenly, cooling, adding ethanol, stirring evenly, cooling to below 40°C, and discharging to obtain phenolic resin A; adding formaldehyde and phenol to a container, stirring evenly, adjusting the pH of the reaction system, heating, vacuum dehydration, heat preservation, cooling, adding ethanol, stirring until completely dissolved, cooling to below 40°C, and discharging to obtain phenolic resin B; adding phenolic resin A and phenolic resin B to a container, stirring evenly, adding phenol-modified self-lubricating microcapsules and hexamethylenetetramine, stirring evenly, adjusting the pH of the reaction system with acid, impregnating wood pulp core paper, assembling, and pressing to obtain a phenolic resin laminate.

Description

Technical Field

[0001] This invention relates to the field of phenolic resin laminate technology, specifically a rapid hot-pressed thin phenolic resin laminate and its preparation method. Background Technology

[0002] Phenolic resin laminates are widely used in structural components and electronic insulation due to their excellent mechanical properties and temperature resistance. However, current phenolic resin laminate manufacturing processes often face problems such as low curing efficiency and long hot-pressing cycles, which restrict the improvement of production efficiency. At the same time, traditional laminates lack toughness, making them prone to cracking during use, and their insufficient wear resistance limits their service life. Furthermore, modifying components introduced to improve performance are prone to agglomeration due to poor interfacial bonding with the resin matrix, affecting overall performance; some systems lack stability at high temperatures and have weak oxidation resistance, further limiting their application under harsh working conditions.

[0003] Therefore, developing phenolic resin laminates that can balance rapid curing, high toughness, low wear, and good oxidation resistance has become an important demand in related fields. Summary of the Invention

[0004] The purpose of this invention is to provide a rapid hot-pressed thin phenolic resin laminate and its preparation method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a rapid hot-pressed thin phenolic resin laminate includes the following preparation steps: S1: Add formaldehyde and phenol to a container, stir evenly, adjust the pH of the reaction system to 9-10 with sodium hydroxide, heat to 85-90℃, dehydrate under vacuum, keep warm for 1.5-2 hours, add urea, stir evenly, cool to 50-55℃, add ethanol, stir evenly, cool to below 40℃, discharge to obtain phenolic resin A. Furthermore, the proportions of each component in the phenolic adhesive A by mass percentage include: 45-50 parts formaldehyde, 30-40 parts phenol, 8-12 parts ethanol, and 3-5 parts urea. Furthermore, in step S1, the dehydration amount is 10-15%; S2: Add formaldehyde and phenol to a container, stir evenly, adjust the pH of the reaction system to 2-3 with acid, heat to 85-90℃, dehydrate under vacuum, keep warm for 3-3.5h, cool to 45-50℃, add ethanol, stir until completely dissolved, cool to below 40℃, discharge to obtain phenolic resin B. Furthermore, the components in the phenolic adhesive B, by mass percentage, include 35-40 parts formaldehyde, 50-55 parts phenol, and 15-20 parts ethanol. Furthermore, in step S2, the acid includes any one of hydrochloric acid, nitric acid, and aminosulfonic acid; Furthermore, in step S2, the amount of water removed is 8-10%; S3: Add phenolic resin A and phenolic resin B to a container and stir evenly. Add phenol-modified self-lubricating microcapsules and hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2-2.5 with acid. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminates. Furthermore, the impregnation temperature is 130-150℃, the impregnation amount is 55-65%, and the volatile matter content is 5-7%; Furthermore, the pressing temperature is 150-175℃, the pressure is 15-20MPa, and the time is 40-120s; Furthermore, in step S3, the acid includes any one of p-toluenesulfonic acid, hydrochloric acid, and aminosulfonic acid; Furthermore, the proportions of each component in the phenolic resin laminate, by mass, include: 40-60 parts of phenolic resin A, 40-60 parts of phenolic resin B, 1-5 parts of phenol-modified self-lubricating microcapsules, and 4-6 parts of hexamethylenetetramine. Furthermore, the preparation method of the phenol-modified self-lubricating microcapsules includes the following steps: Step (1): Add magnesium oxide and silicon dioxide to deionized water, stir evenly, adjust the pH of the reaction system to 13.5-14.0 with magnesium hydroxide, heat to 300-305℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80-85℃ to obtain magnesium hydroxide silicate powder; Furthermore, in the preparation process of the magnesium hydroxide silicate powder, the mass ratio of magnesium oxide to silicon dioxide is 1:1; Step (2): Add magnesium hydroxide silicate powder to a mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride, stir and react for 24-30 h, filter, wash, and vacuum dry at 60-65 °C to obtain modified magnesium hydroxide silicate powder; Furthermore, in the mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride, the mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride is (1.2-2):(2-3); the pH of the mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride is 8.5-9. Step (3): Add modified magnesium hydroxide silicate powder, sodium molybdate, thiourea, and D-glucose to deionized water, stir evenly, heat to 220-225℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80-85℃ to obtain composite powder; Furthermore, in the preparation process of the composite powder, the mass ratio of modified magnesium hydroxide silicate powder: sodium molybdate: thiourea: D-glucose is (1-1.2):(2.610-2.805):(4.05-4.15):(0.325-0.353); Step (4): Add potassium persulfate and phosphorus pentoxide to concentrated sulfuric acid and stir for 12-13 hours. Add graphite powder and stir for 5-5.5 hours. Heat to 90-95℃ and react for 5-5.5 hours. Add deionized water to dilute, filter, and vacuum dry at 60-65℃ to obtain graphite oxide. Furthermore, in the preparation process of the graphite oxide, the mass ratio of potassium persulfate: phosphorus pentoxide: graphite powder is 5:5:(1-1.5); Step (5): Add graphene oxide to concentrated sulfuric acid, stir evenly, add potassium permanganate under ice bath conditions, heat to 35-40℃ for 2-2.5h, add deionized water under ice bath conditions, stir for 12-16h, add 30% hydrogen peroxide solution until the solution is bright yellow, centrifuge, wash with 5% hydrochloric acid solution, wash the product until neutral, freeze dry to obtain graphene oxide; Furthermore, in the preparation process of the graphene oxide, the mass ratio of graphene oxide to potassium permanganate is (1.5-2):8; Step (6): Add graphene oxide to deionized water, sonicate for 30-45 min, add sodium hydroxide and chloroacetic acid, sonicate for 3-3.5 h, neutralize the reaction system with 1 mol / L hydrochloric acid, wash, dialyze to obtain carboxylated graphene oxide; add carboxylated graphene oxide to deionized water, sonicate to obtain a suspension; Furthermore, in the preparation process of the carboxylated graphene oxide, the mass ratio of graphene oxide:sodium hydroxide:chloroacetic acid is (0.02-0.03):1.2:1; Furthermore, the concentration of the suspension is 2-2.5 mg / mL; Step (7): Add the composite powder and oleic acid to the poly-α-olefin and ultrasonically disperse for 30-45 min to obtain the core material; add the core material and sodium dodecyl sulfate to formamide and stir for 2-2.5 h to obtain a mixed emulsion; add tetrabutyl titanate and stir for 40-45 min; add aqueous formamide solution and stir for 3-3.5 h; centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50-55℃ to obtain PAO microcapsules; Furthermore, in the preparation process of the core material, the mass ratio of polyα-olefin: composite powder: oleic acid is 1:(0.03-0.06):(0.01-0.012); Furthermore, in the preparation process of the PAO microcapsules, the mass ratio of core material: sodium dodecyl sulfate: tetrabutyl titanate is 10:(3.3-3.5):(6-6.4); Furthermore, in the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; Step (8): Add PAO microcapsules to deionized water, stir evenly, add suspension, stir reaction for 1-1.5h, filter, vacuum dry at 50-55℃ to obtain self-lubricating microcapsules; add self-lubricating microcapsules to deionized water, ultrasonically disperse, add phenol monomer, adjust the pH of the reaction system to 2.2-2.4, heat to 85-90℃ for 4-4.5h, freeze dry to obtain phenol-modified self-lubricating microcapsules; Furthermore, in the preparation process of the self-lubricating microcapsules, the mass ratio of PAO microcapsules to carboxylated graphene oxide is (1.5-2):(0.03-0.05); Furthermore, in the preparation process of the phenol-modified self-lubricating microcapsules, the mass ratio of phenol monomer to self-lubricating microcapsules is (50-100):200.

[0006] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes phenol-modified microcapsules, taking advantage of the acidic environment of phenol to promote in-situ polymerization of phenolic resin, accelerating the curing reaction and shortening the hot-pressing time to 40-120 seconds, significantly improving production efficiency. Phenol monomers grafted onto the carboxylated graphene oxide surface of the microcapsules catalyze the hydroxymethylation reaction of the phenolic resin. Simultaneously, the phenol on the microcapsule surface participates in copolymerization, forming a resin-microcapsule interpenetrating network, achieving rapid cross-linking with a short curing time. Furthermore, the carboxylic acid groups of the carboxylated graphene oxide react with the hydroxyl / amino groups of the resin, covalently fixing the microcapsules and preventing aggregation during hot pressing.

[0007] 2. This invention utilizes the microcapsule rupture under frictional stress to release the PAO core material, forming a lubricating film. Simultaneously, the magnesium hydroxide silicate in the composite powder within the PAO core material provides Mg and Si elements, forming an MgO-containing lubricating layer and reducing the coefficient of friction. Furthermore, a polydopamine coating is additionally applied to the surface of the magnesium hydroxide silicate. In a 220°C hydrothermal environment, its carbon skeleton can fuse with the amorphous carbon generated by subsequent glucose carbonization, further enhancing the coating effect on MoS2. This MoS2 coating improves dispersibility and oxidation resistance. The PDA coating on the MSH@PDA surface itself contains carbon, and its carbonization products can form a "double carbon coating" with the amorphous carbon from glucose carbonization, further optimizing the dispersibility of the composite powder.

[0008] 3. This invention uses a carboxylated graphene oxide coating layer to isolate the PAO core material from oxygen, delaying oxidative degradation during hot pressing and use. Phenol grafted onto the surface of the microcapsule increases the hardness of the shell, preventing the microcapsule from rupturing prematurely under high pressure, thus achieving "release on demand". The microcapsule acts as a "nano-crosslinking point", forming hydrogen bonds / covalent bonds with the resin through the hydroxyl groups of phenol. At the same time, the two-dimensional sheets of graphene oxide hinder crack propagation and improve the mechanical properties of the laminate. Detailed Implementation

[0009] 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.

[0010] Example 1: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: S1: 45 parts formaldehyde and 50 parts phenol are added to a container and stirred evenly. The pH of the reaction system is adjusted to 9 using sodium hydroxide. The mixture is heated to 85°C, vacuum dehydrated, and kept warm for 1.5 hours. 3 parts urea are added and stirred evenly. The mixture is cooled to 50°C. 8 parts ethanol are added and stirred evenly. The mixture is cooled to below 40°C and discharged to obtain phenolic resin A. S2: Add 35 parts formaldehyde and 50 parts phenol to a container, stir evenly, adjust the pH of the reaction system to 2 with hydrochloric acid, heat to 85°C, dehydrate under vacuum, keep warm for 3 hours, cool down to 45°C, add 15 parts ethanol, stir until completely dissolved, cool down to below 40°C, discharge to obtain phenolic resin B. S3: Add 50 parts of phenolic resin A and 50 parts of phenolic resin B to a container and stir evenly. Add 2 parts of phenol-modified self-lubricating microcapsules and 5 parts of hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2 using p-toluenesulfonic acid. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminate. The preparation method of the phenol-modified self-lubricating microcapsules includes the following steps: Step (1): Add 2g magnesium oxide and 2g silicon dioxide to 100mL of deionized water, stir evenly, adjust the pH of the reaction system to 13.5 with magnesium hydroxide, heat to 300℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain magnesium hydroxide silicate powder. Step (2): Add 50 mg of magnesium hydroxide silicate powder to a mixed solution of 1.2 g of tris(hydroxymethyl)aminomethane and 2 g of dopamine hydrochloride, stir and react for 24 h, filter, wash, and vacuum dry at 60 °C to obtain modified magnesium hydroxide silicate powder. Step (3): Add 1g of modified magnesium hydroxide silicate powder, 2.610g of sodium molybdate, 4.15g of thiourea and 0.325g of D-glucose to deionized water, stir evenly, heat to 220℃ and react for 24h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain composite powder; Step (4): Add 5g potassium persulfate and 5g phosphorus pentoxide to concentrated sulfuric acid, stir for 12h, add 1.5g graphite powder, stir for 5h, heat to 90℃ and react for 5h, add deionized water to dilute, filter, and vacuum dry at 60℃ to obtain graphite oxide. Step (5): Add 1.5g of graphene oxide to concentrated sulfuric acid, stir evenly, add 8g of potassium permanganate under ice bath conditions, heat to 35℃ and react for 2h, add deionized water under ice bath conditions, stir for 12h, add 30% hydrogen peroxide solution until the solution is bright yellow, centrifuge, wash with 5% hydrochloric acid solution, wash the product until neutral, freeze dry to obtain graphene oxide; Step (6): Add 20 mg of graphene oxide to deionized water, sonicate for 30 min, add 1.2 g of sodium hydroxide and 1 g of chloroacetic acid, sonicate for 3 h, neutralize the reaction system with 1 mol / L hydrochloric acid, wash, dialyze to obtain carboxylated graphene oxide; add carboxylated graphene oxide to deionized water, sonicate to obtain a 2 mg / mL suspension. Step (7): Add 30 mg of composite powder and 10 mg of oleic acid to 1 g of poly-α-olefin and ultrasonically disperse for 30 min to obtain the core material; add 10 g of core material and 3.3 g of sodium dodecyl sulfate to formamide and stir for 2 h to obtain a mixed emulsion; add 6.4 g of tetrabutyl titanate, stir for 40 min, add formamide aqueous solution, stir and react for 3 h, centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; Step (8): Add 1.5g of PAO microcapsules to deionized water, stir evenly, add 15mL of suspension, stir and react for 1h, filter, and vacuum dry at 50℃ to obtain self-lubricating microcapsules; add 200mg of self-lubricating microcapsules to deionized water, ultrasonically disperse, add 50mg of phenol monomer, adjust the pH of the reaction system to 2.2, heat to 85℃ and react for 4h, freeze dry to obtain phenol-modified self-lubricating microcapsules.

[0011] Example 2: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: S3: Add 50 parts of phenolic adhesive A and 50 parts of phenolic adhesive B to a container, stir evenly, add 5 parts of phenol-modified self-lubricating microcapsules and 5 parts of hexamethylenetetramine, stir evenly, adjust the pH of the reaction system to 2 using p-toluenesulfonic acid, impregnate the wood pulp core paper, assemble the laminate, press it together, and obtain the phenolic resin laminate; The remaining steps are the same as in Example 1.

[0012] Example 3: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: Step (6): 20 mg of graphene oxide is added to deionized water, ultrasonically dispersed for 30 min, 1.2 g of sodium hydroxide and 1 g of chloroacetic acid are added, ultrasonically treated for 3 h, the reaction system is neutralized with 1 mol / L hydrochloric acid, washed, and dialyzed to obtain carboxylated graphene oxide; the carboxylated graphene oxide is added to deionized water, ultrasonically dispersed to obtain a 2.5 mg / mL suspension; Step (7): Add 30 mg of composite powder and 10 mg of oleic acid to 1 g of poly-α-olefin and ultrasonically disperse for 30 min to obtain the core material; add 10 g of core material and 3.3 g of sodium dodecyl sulfate to formamide and stir for 2 h to obtain a mixed emulsion; add 6.4 g of tetrabutyl titanate, stir for 40 min, add formamide aqueous solution, stir and react for 3 h, centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; Step (8): Add 1.5g of PAO microcapsules to deionized water, stir evenly, add 20mL of suspension, stir and react for 1h, filter, and vacuum dry at 50℃ to obtain self-lubricating microcapsules; add 200mg of self-lubricating microcapsules to deionized water, ultrasonically disperse, add 50mg of phenol monomer, adjust the pH of the reaction system to 2.2, heat to 85℃ and react for 4h, freeze dry to obtain phenol-modified self-lubricating microcapsules; The remaining steps are the same as in Example 1.

[0013] Example 4: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: Step (7): 60 mg of composite powder and 10 mg of oleic acid are added to 1 g of poly-α-olefin and ultrasonically dispersed for 30 min to obtain core material; 10 g of core material and 3.3 g of sodium dodecyl sulfate are added to formamide and stirred for 2 h to obtain mixed emulsion; 6.4 g of tetrabutyl titanate is stirred for 40 min, and formamide aqueous solution is added and stirred for 3 h. After centrifugation, the supernatant is collected, washed with deionized water and anhydrous ethanol, and vacuum dried at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; The remaining steps are the same as in Example 1.

[0014] Comparative Example 1: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: S1: 45 parts formaldehyde and 50 parts phenol are added to a container and stirred evenly. The pH of the reaction system is adjusted to 9 using sodium hydroxide. The mixture is heated to 85°C, vacuum dehydrated, and kept warm for 1.5 hours. 3 parts urea are added and stirred evenly. The mixture is cooled to 50°C. 8 parts ethanol are added and stirred evenly. The mixture is cooled to below 40°C and discharged to obtain phenolic resin A. S2: Add 35 parts formaldehyde and 50 parts phenol to a container, stir evenly, adjust the pH of the reaction system to 2 with hydrochloric acid, heat to 85°C, dehydrate under vacuum, keep warm for 3 hours, cool down to 45°C, add 15 parts ethanol, stir until completely dissolved, cool down to below 40°C, discharge to obtain phenolic resin B. S3: Add 50 parts of phenolic resin A and 50 parts of phenolic resin B to a container and stir evenly. Add 2 parts of self-lubricating microcapsules and 5 parts of hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2 using p-toluenesulfonic acid. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminates. The method for preparing the self-lubricating microcapsules includes the following steps: Step (1): Add 2g magnesium oxide and 2g silicon dioxide to 100mL of deionized water, stir evenly, adjust the pH of the reaction system to 13.5 with magnesium hydroxide, heat to 300℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain magnesium hydroxide silicate powder. Step (2): Add 50 mg of magnesium hydroxide silicate powder to a mixed solution of 1.2 g of tris(hydroxymethyl)aminomethane and 2 g of dopamine hydrochloride, stir and react for 24 h, filter, wash, and vacuum dry at 60 °C to obtain modified magnesium hydroxide silicate powder. Step (3): Add 1g of modified magnesium hydroxide silicate powder, 2.610g of sodium molybdate, 4.15g of thiourea and 0.325g of D-glucose to deionized water, stir evenly, heat to 220℃ and react for 24h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain composite powder; Step (4): Add 5g potassium persulfate and 5g phosphorus pentoxide to concentrated sulfuric acid, stir for 12h, add 1.5g graphite powder, stir for 5h, heat to 90℃ and react for 5h, add deionized water to dilute, filter, and vacuum dry at 60℃ to obtain graphite oxide. Step (5): Add 1.5g of graphene oxide to concentrated sulfuric acid, stir evenly, add 8g of potassium permanganate under ice bath conditions, heat to 35℃ and react for 2h, add deionized water under ice bath conditions, stir for 12h, add 30% hydrogen peroxide solution until the solution is bright yellow, centrifuge, wash with 5% hydrochloric acid solution, wash the product until neutral, freeze dry to obtain graphene oxide; Step (6): Add 20 mg of graphene oxide to deionized water, sonicate for 30 min, add 1.2 g of sodium hydroxide and 1 g of chloroacetic acid, sonicate for 3 h, neutralize the reaction system with 1 mol / L hydrochloric acid, wash, dialyze to obtain carboxylated graphene oxide; add carboxylated graphene oxide to deionized water, sonicate to obtain a 2 mg / mL suspension. Step (7): Add 30 mg of composite powder and 10 mg of oleic acid to 1 g of poly-α-olefin and ultrasonically disperse for 30 min to obtain the core material; add 10 g of core material and 3.3 g of sodium dodecyl sulfate to formamide and stir for 2 h to obtain a mixed emulsion; add 6.4 g of tetrabutyl titanate, stir for 40 min, add formamide aqueous solution, stir and react for 3 h, centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; Step (8): Add 1.5g of PAO microcapsules to deionized water, stir evenly, add 15mL of suspension, stir and react for 1h, filter, and vacuum dry at 50℃ to obtain self-lubricating microcapsules.

[0015] Comparative Example 2: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: S1: 45 parts formaldehyde and 50 parts phenol are added to a container and stirred evenly. The pH of the reaction system is adjusted to 9 using sodium hydroxide. The mixture is heated to 85°C, vacuum dehydrated, and kept warm for 1.5 hours. 3 parts urea are added and stirred evenly. The mixture is cooled to 50°C. 8 parts ethanol are added and stirred evenly. The mixture is cooled to below 40°C and discharged to obtain phenolic resin A. S2: Add 35 parts formaldehyde and 50 parts phenol to a container, stir evenly, adjust the pH of the reaction system to 2 with hydrochloric acid, heat to 85°C, dehydrate under vacuum, keep warm for 3 hours, cool down to 45°C, add 15 parts ethanol, stir until completely dissolved, cool down to below 40°C, discharge to obtain phenolic resin B. S3: Add 50 parts of phenolic resin A and 50 parts of phenolic resin B to a container and stir evenly. Add 2 parts of PAO microcapsules and 5 parts of hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2 using p-toluenesulfonic acid. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminates. The method for preparing the PAO microcapsules includes the following steps: Step (1): Add 2g magnesium oxide and 2g silicon dioxide to 100mL of deionized water, stir evenly, adjust the pH of the reaction system to 13.5 with magnesium hydroxide, heat to 300℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain magnesium hydroxide silicate powder. Step (2): Add 50 mg of magnesium hydroxide silicate powder to a mixed solution of 1.2 g of tris(hydroxymethyl)aminomethane and 2 g of dopamine hydrochloride, stir and react for 24 h, filter, wash, and vacuum dry at 60 °C to obtain modified magnesium hydroxide silicate powder. Step (3): Add 1g of modified magnesium hydroxide silicate powder, 2.610g of sodium molybdate, 4.15g of thiourea and 0.325g of D-glucose to deionized water, stir evenly, heat to 220℃ and react for 24h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain composite powder; Step (4): Add 5g potassium persulfate and 5g phosphorus pentoxide to concentrated sulfuric acid, stir for 12h, add 1.5g graphite powder, stir for 5h, heat to 90℃ and react for 5h, add deionized water to dilute, filter, and vacuum dry at 60℃ to obtain graphite oxide. Step (5): Add 1.5g of graphene oxide to concentrated sulfuric acid, stir evenly, add 8g of potassium permanganate under ice bath conditions, heat to 35℃ and react for 2h, add deionized water under ice bath conditions, stir for 12h, add 30% hydrogen peroxide solution until the solution is bright yellow, centrifuge, wash with 5% hydrochloric acid solution, wash the product until neutral, freeze dry to obtain graphene oxide; Step (6): Add 20 mg of graphene oxide to deionized water, sonicate for 30 min, add 1.2 g of sodium hydroxide and 1 g of chloroacetic acid, sonicate for 3 h, neutralize the reaction system with 1 mol / L hydrochloric acid, wash, dialyze to obtain carboxylated graphene oxide; add carboxylated graphene oxide to deionized water, sonicate to obtain a 2 mg / mL suspension. Step (7): Add 30 mg of composite powder and 10 mg of oleic acid to 1 g of poly-α-olefin and ultrasonically disperse for 30 min to obtain the core material; add 10 g of core material and 3.3 g of sodium dodecyl sulfate to formamide and stir for 2 h to obtain a mixed emulsion; add 6.4 g of tetrabutyl titanate, stir for 40 min, add formamide aqueous solution, stir and react for 3 h, centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5.

[0016] Comparative Example 3: A method for preparing a rapid hot-pressed thin phenolic resin laminate, comprising the following preparation steps: S1: 45 parts formaldehyde and 50 parts phenol are added to a container and stirred evenly. The pH of the reaction system is adjusted to 9 using sodium hydroxide. The mixture is heated to 85°C, vacuum dehydrated, and kept warm for 1.5 hours. 3 parts urea are added and stirred evenly. The mixture is cooled to 50°C. 8 parts ethanol are added and stirred evenly. The mixture is cooled to below 40°C and discharged to obtain phenolic resin A. S2: Add 35 parts formaldehyde and 50 parts phenol to a container, stir evenly, adjust the pH of the reaction system to 2 with hydrochloric acid, heat to 85°C, dehydrate under vacuum, keep warm for 3 hours, cool down to 45°C, add 15 parts ethanol, stir until completely dissolved, cool down to below 40°C, discharge to obtain phenolic resin B. S3: Add 50 parts of phenolic resin A and 50 parts of phenolic resin B to a container and stir evenly. Add 2 parts of phenol-modified self-lubricating microcapsules and 5 parts of hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2 using p-toluenesulfonic acid. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminate. The preparation method of the phenol-modified self-lubricating microcapsules includes the following steps: Step (1): Add 2g magnesium oxide and 2g silicon dioxide to 100mL of deionized water, stir evenly, adjust the pH of the reaction system to 13.5 with magnesium hydroxide, heat to 300℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80℃ to obtain magnesium hydroxide silicate powder. Step (2): Add 5g potassium persulfate and 5g phosphorus pentoxide to concentrated sulfuric acid and stir for 12h. Add 1.5g graphite powder and stir for 5h. Heat to 90℃ and react for 5h. Add deionized water to dilute, filter, and vacuum dry at 60℃ to obtain graphite oxide. Step (3): Add 1.5g of graphene oxide to concentrated sulfuric acid, stir evenly, add 8g of potassium permanganate under ice bath conditions, heat to 35℃ and react for 2h, add deionized water under ice bath conditions, stir for 12h, add 30% hydrogen peroxide solution until the solution is bright yellow, centrifuge, wash with 5% hydrochloric acid solution, wash the product until neutral, freeze dry to obtain graphene oxide; Step (4): Add 20 mg of graphene oxide to deionized water, sonicate for 30 min, add 1.2 g of sodium hydroxide and 1 g of chloroacetic acid, sonicate for 3 h, neutralize the reaction system with 1 mol / L hydrochloric acid, wash, dialyze to obtain carboxylated graphene oxide; add carboxylated graphene oxide to deionized water, sonicate to obtain a 2 mg / mL suspension. Step (5): Add 30 mg magnesium hydroxide silicate powder and 10 mg oleic acid to 1 g polyα-olefin, and ultrasonically disperse for 30 min to obtain core material; add 10 g core material and 3.3 g sodium dodecyl sulfate to formamide, stir for 2 h to obtain mixed emulsion; add 6.4 g tetrabutyl titanate, stir for 40 min, add formamide aqueous solution, stir and react for 3 h, centrifuge, collect the supernatant, wash with deionized water and anhydrous ethanol, and vacuum dry at 50 °C to obtain PAO microcapsules; In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; Step (6): Add 1.5g of PAO microcapsules to deionized water, stir evenly, add 15mL of suspension, stir and react for 1h, filter, and vacuum dry at 50℃ to obtain self-lubricating microcapsules; add 200mg of self-lubricating microcapsules to deionized water, ultrasonically disperse, add 50mg of phenol monomer, adjust the pH of the reaction system to 2.2, heat to 85℃ and react for 4h, freeze dry to obtain phenol-modified self-lubricating microcapsules.

[0017] Experiment: Mechanical property testing: Three-point bending test was used to measure bending strength and fracture toughness. The sample size was 40mm×8mm×4mm, the span was 32mm, and the loading speed was 2mm / min. Wear resistance test: Pin-disc friction test, the mating part is GCr15 steel ball (diameter 6mm), load 20N, rotation speed 200rpm, test for 120min, and record the friction coefficient and wear rate; The experimental data are shown in Table 1 below.

[0018] Table 1 Performance Test Data of Phenolic Resin Laminate

[0019] Conclusion: The phenolic resin laminate prepared by this invention has excellent mechanical properties, abrasion resistance and oxidation resistance.

[0020] In Comparative Example 1, there was no phenol modification, and the self-lubricating microcapsules did not react with the phenol monomer. In Comparative Example 2, the microcapsules only contained PAO-TiO2 shells and composite powders, without carboxylated graphene oxide. In Comparative Example 3, the composite powders only contained MSH magnesium hydroxide silicate powders, which led to a decrease in the performance of the phenolic resin laminate.

[0021] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for producing a rapidly hot-pressed thin phenol-formaldehyde resin laminated board, characterized by: The preparation steps include the following: S1: Add formaldehyde and phenol to a container, stir evenly, adjust the pH of the reaction system to 9-10, heat to 85-90℃, dehydrate under vacuum, keep warm, add urea, stir evenly, cool to 50-55℃, add ethanol, stir evenly, cool to below 40℃, discharge, and obtain phenolic resin A. S2: Add formaldehyde and phenol to a container, stir evenly, adjust the pH of the reaction system to 2-3, heat to 85-90℃, dehydrate under vacuum, keep warm, cool to 45-50℃, add ethanol, stir until completely dissolved, cool to below 40℃, discharge to obtain phenolic resin B. S3: Add phenolic resin A and phenolic resin B to a container and stir evenly. Add phenol-modified self-lubricating microcapsules and hexamethylenetetramine and stir evenly. Adjust the pH of the reaction system to 2-2.

5. Impregnate the wood pulp core paper, assemble the blanks, and press them together to obtain phenolic resin laminates. The preparation method of the phenol-modified self-lubricating microcapsules includes the following steps: adding PAO microcapsules to deionized water, stirring evenly, adding a suspension, stirring and reacting, filtering, and vacuum drying to obtain self-lubricating microcapsules; adding the self-lubricating microcapsules to deionized water, ultrasonically dispersing, adding phenol monomer, adjusting the pH of the reaction system to 2.2-2.4, heating to 85-90℃ for reaction, and freeze-drying to obtain phenol-modified self-lubricating microcapsules; The preparation method of the PAO microcapsules includes the following steps: adding composite powder and oleic acid to polyα-olefin, ultrasonically dispersing for 30-45 min to obtain core material; adding core material and sodium dodecyl sulfate to formamide, stirring for 2-2.5 h to obtain mixed emulsion; adding tetrabutyl titanate, stirring for 40-45 min, adding aqueous formamide solution, stirring and reacting for 3-3.5 h, centrifuging, collecting the supernatant, washing with deionized water and anhydrous ethanol, and vacuum drying at 50-55℃ to obtain PAO microcapsules; In the preparation of the core material, the mass ratio of polyα-olefin: composite powder: oleic acid is 1:(0.03-0.06):(0.01-0.012); In the preparation of PAO microcapsules, the mass ratio of core material: sodium dodecyl sulfate: tetrabutyl titanate is 10:(3.3-3.5):(6-6.4); In the formamide aqueous solution, the volume ratio of formamide to deionized water is 30:5; The method for preparing the suspension includes the following steps: adding graphene oxide to deionized water, ultrasonically dispersing for 30-45 min, adding sodium hydroxide and chloroacetic acid, ultrasonically treating for 3-3.5 h, neutralizing the reaction system with 1 mol / L hydrochloric acid, washing, and dialysis to obtain carboxylated graphene oxide; adding the carboxylated graphene oxide to deionized water, ultrasonically dispersing to obtain the suspension. In the preparation of carboxylated graphene oxide, the mass ratio of graphene oxide:sodium hydroxide:chloroacetic acid is (0.02-0.03):1.2:1; The concentration of the suspension is 2-2.5 mg / mL; The preparation method of the composite powder includes the following steps: adding modified magnesium hydroxide silicate powder, sodium molybdate, thiourea, and D-glucose to deionized water, stirring evenly, heating to 220-225℃ for 24-30h, cooling to room temperature, centrifuging, and vacuum drying at 80-85℃ to obtain the composite powder; In the preparation of the composite powder, the mass ratio of modified magnesium hydroxide silicate powder: sodium molybdate: thiourea: D-glucose is (1-1.2):(2.610-2.805):(4.05-4.15):(0.325-0.353). The preparation method of the modified magnesium hydroxide silicate powder includes the following steps: Step (1): Add magnesium oxide and silicon dioxide to deionized water, stir evenly, adjust the pH of the reaction system to 13.5-14.0 with magnesium hydroxide, heat to 300-305℃ and react for 24-30h, cool to room temperature, centrifuge, and vacuum dry at 80-85℃ to obtain magnesium hydroxide silicate powder; Step (2): Add magnesium hydroxide silicate powder to a mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride, stir and react for 24-30 h, filter, wash, and vacuum dry at 60-65 °C to obtain modified magnesium hydroxide silicate powder; In the preparation of magnesium hydroxide silicate powder, the mass ratio of magnesium oxide to silicon dioxide is 1:

1. In the mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride, the mass ratio of tris(hydroxymethyl)aminomethane to dopamine hydrochloride is (1.2-2):(2-3); the pH of the mixed solution of tris(hydroxymethyl)aminomethane and dopamine hydrochloride is 8.5-9.

2. The method of claim 1, wherein the method is characterized by: The components of phenolic adhesive A are expressed in parts by mass as follows: formaldehyde 45-50 parts, phenol 30-40 parts, ethanol 8-12 parts, and urea 3-5 parts. The components in phenolic adhesive B, by mass percentage, include 35-40 parts formaldehyde, 50-55 parts phenol, and 15-20 parts ethanol. The components in the phenolic resin laminate, by mass percentage, include: 40-60 parts of phenolic resin A, 40-60 parts of phenolic resin B, 1-5 parts of phenol-modified self-lubricating microcapsules, and 4-6 parts of hexamethylenetetramine.

3. The method of claim 1, wherein the method is characterized by: In the preparation of self-lubricating microcapsules, the mass ratio of PAO microcapsules to carboxylated graphene oxide is (1.5-2):(0.03-0.05). In the preparation of phenol-modified self-lubricating microcapsules, the mass ratio of phenol monomer to self-lubricating microcapsules is (50-100):

200.

4. The method of claim 1, wherein the method is characterized by: The method for preparing graphene oxide includes the following steps: adding graphene oxide to concentrated sulfuric acid, stirring until homogeneous, adding potassium permanganate under ice bath conditions, heating to 35-40℃ for 2-2.5h, adding deionized water under ice bath conditions, stirring for 12-16h, adding 30% hydrogen peroxide solution until the solution is bright yellow, centrifuging, washing with 5% hydrochloric acid solution, washing the product again until neutral, and freeze-drying to obtain graphene oxide; In the preparation of graphene oxide, the mass ratio of graphene oxide to potassium permanganate is (1.5-2):

8.

5. A method of producing a rapid hot-pressed thin-type phenol-formaldehyde resin laminated board according to claim 4, characterized by: The method for preparing the graphite oxide includes the following steps: adding potassium persulfate and phosphorus pentoxide to concentrated sulfuric acid and stirring for 12-13 hours; adding graphite powder and stirring for 5-5.5 hours; heating to 90-95°C and reacting for 5-5.5 hours; adding deionized water to dilute; filtering; and vacuum drying at 60-65°C to obtain graphite oxide. In the preparation of graphite oxide, the mass ratio of potassium persulfate: phosphorus pentoxide: graphite powder is 5:5:(1-1.5).

6. The phenolic resin laminate prepared by the method for preparing a rapid hot-pressed thin phenolic resin laminate according to any one of claims 1-5.

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