A high-wear-resistance polyurethane coating wheel for PCB industry and a preparation method thereof

Abstract

The application belongs to the technical field of polyurethane materials, and particularly relates to a high-wear-resistance polyurethane coating wheel for the PCB industry and a preparation method thereof. The preparation method comprises the following steps: S1, pretreating a metal shaft core; S2, placing the pretreated metal shaft core in a mold, then adding a liquid polyurethane pre-embedded shaft core, and heat treating to form an elastic buffer layer; S3, mixing polycaprolactone polyol and polytetrahydrofuran ether polyol, then vacuum dehydrating, then adding a chain extender, a functional filler, a coupling agent and an antioxidant, and uniformly dispersing to obtain component A, preheating isocyanate, mixing and uniformly stirring the isocyanate with the component A, and vacuum deaerating to obtain a casting material; and S4, using the casting material to perform casting forming on the metal shaft core with the elastic buffer layer, heat forming, and finishing to form a wear-resistant working layer, so as to obtain the high-wear-resistance polyurethane coating wheel for the PCB industry. The application effectively improves the wear resistance and hardness of the material, and realizes good acid and alkali resistance.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane materials technology, specifically relating to a high wear-resistant polyurethane coating wheel for the PCB industry and its preparation method. Background Technology

[0002] Polyurethane (PU) is a high molecular polymer whose main chain contains urethane groups, polymerized from isocyanate monomers and hydroxyl compounds. Its properties are highly tunable. During the manufacturing process, different raw materials and formulation designs can produce different materials that are suitable for a wide temperature range. It is widely used in transportation, construction, machinery, electronic equipment, mining and metallurgy, petrochemicals, water conservancy, national defense, medical and health fields in the form of products such as foam plastics, elastomers, coatings, adhesives, fibers, synthetic leather, waterproof materials and paving materials.

[0003] Polyurethane coating wheels used in the PCB industry are mainly used for precision coating of solder resist ink, photosensitive adhesive, or character ink. With its excellent solvent resistance and elasticity, it ensures uniform coating while significantly reducing the frequency of replacement and quality problems caused by wear. Most polyurethane coating wheels adopt a structure of "metal wheel core + polyurethane coating", which has the following characteristics: (1) Uniform coating and high quality. With its excellent elasticity, it can adapt well to inks of different viscosities, effectively avoiding common defects such as bubbles, streaks, or uneven thickness, and ensuring coating quality; (2) Durable and low cost. Compared with ordinary coating wheels, it has a longer service life, reduces the trouble of frequent downtime for replacement, and can reduce production costs in the long run.

[0004] In the existing technology, coating rollers used in the PCB industry are prone to swelling and shedding due to long-term contact with inks, solvents and acidic / alkaline solutions during the PCB manufacturing process. Their insufficient chemical resistance and abrasion resistance, as well as poor hardness stability, can lead to a decrease in coating thickness uniformity. In severe cases, this can cause defects such as open circuits and short circuits, thereby reducing production yield.

[0005] Therefore, there is an urgent need for a high-wear-resistant polyurethane coating wheel. Through structural design and the introduction of functional components, the wear resistance and hardness of the material can be improved, and good acid and alkali resistance can be achieved, so that it can be better applied in the PCB industry. Summary of the Invention

[0006] The purpose of this invention is to provide a high wear-resistant polyurethane coating wheel for the PCB industry and its preparation method. This invention significantly improves the wear resistance and chemical resistance of the coating wheel by optimizing the polyurethane material formulation, introducing functional fillers, and improving the molding process, ensuring good coating uniformity, extending service life, and reducing the material costs of PCB manufacturers.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry, comprising the following steps:

[0009] S1. Pre-treat the metal shaft core to obtain the pre-treated metal shaft core;

[0010] S2. Place the pretreated metal shaft core in a mold, then add liquid polyurethane to embed the shaft core, and heat treat to form an elastic buffer layer to obtain a metal shaft core with an elastic buffer layer.

[0011] S3. Polycaprolactone polyol and polytetrahydrofuran ether polyol are mixed and then vacuum dehydrated. Then, chain extender, functional filler, coupling agent and antioxidant are added and dispersed evenly to obtain component A. Isocyanate is preheated and mixed with component A and stirred evenly. Vacuum degassing is then performed to obtain casting material.

[0012] S4. The metal shaft core with elastic buffer layer is cast and molded using the castable material, thermoformed, and precision machined to form a wear-resistant working layer, thereby obtaining a high wear-resistant polyurethane coated wheel for the PCB industry.

[0013] As a preferred embodiment, the metal shaft core in step S1 is made of aluminum alloy or stainless steel and its surface is sandblasted.

[0014] As a preferred embodiment, the pretreatment conditions in step S1 are as follows: after degreasing and derusting the metal shaft core, it is sandblasted to a thickness of 5~8μm, uniformly coated with a base coat adhesive Chemlock 218, and then dried.

[0015] As a preferred embodiment, the heat treatment conditions in step S2 are: curing at 80~100℃ for 1~3 hours.

[0016] As a preferred embodiment, the thickness of the elastic buffer layer in step S2 is 3~8mm.

[0017] As a preferred embodiment, the vacuum dehydration conditions in step S3 are as follows: vacuum dehydration at 100~120℃ for 1~2 hours, followed by cooling to 60~80℃ after dehydration is completed.

[0018] As a preferred embodiment, the preheating conditions in step S3 are: a temperature of 70~75℃.

[0019] As a preferred embodiment, the thermoforming conditions in step S4 are as follows: first, cure at 90~100℃ for 2~3 hours, and then cure at 100~120℃ for 8~9 hours after demolding.

[0020] As a preferred embodiment, the finishing conditions in step S4 are: precision grinding to make the wheel surface roundness ≤ 0.02 mm and the surface roughness 0.5~0.8 μm.

[0021] As a preferred embodiment, the thickness of the wear-resistant working layer in step S4 is 5~15mm.

[0022] As a preferred embodiment, the components, by weight, include: 60-80 parts of polycaprolactone polyol, 20-40 parts of polytetrahydrofuran ether polyol, 8-15 parts of chain extender, 3-8 parts of functional filler, 0.5-1.5 parts of coupling agent, 0.3-0.8 parts of antioxidant, and 80-100 parts of isocyanate.

[0023] As a preferred embodiment, the polycaprolactone polyol is a polycaprolactone triol with a molecular weight of 200-600 and a hydroxyl value of 300-600 mg KOH / g.

[0024] As a preferred embodiment, the polycaprolactone polyol is either polycaprolactone triol PCL303 or polycaprolactone triol PCL305 from Guanghua Weiye.

[0025] The polycaprolactone polyol of the present invention uses a polycaprolactone triol containing three hydroxyl groups, and controls its molecular weight to be 200-600 and its hydroxyl value to be 300-600 mg KOH / g. At the same time, the liquid state of the polycaprolactone polyol combined with the high hydroxyl value can ensure the reaction is complete, thereby obtaining good comprehensive performance.

[0026] As a preferred embodiment, the chain extender is ethylenediamine and 4,4'-methylenebis(2-chloroaniline);

[0027] The mass ratio of ethylenediamine to 4,4'-methylene-bis(2-chloroaniline) in the chain extender is (1~2):1.

[0028] This invention uses ethylenediamine and 4,4'-methylenebis(2-chloroaniline) as compounding chain extenders. Ethylenediamine is a small-molecule aliphatic diamine with extremely high reactivity, which can effectively improve the crosslinking density. 4,4'-methylenebis(2-chloroaniline) can provide a regular and tough benzene ring structure. By controlling the mass ratio of the two, a good compounding effect is ensured, thereby improving the overall performance of the material.

[0029] As a preferred embodiment, the functional filler is surface-modified silicon carbide composite powder;

[0030] The preparation method of the surface-modified silicon carbide composite powder is as follows: silicon carbide composite powder is prepared by using polycarbosilane and carbon nanotubes as raw materials, and then the surface of the silicon carbide composite powder is modified by using dopamine hydrochloride to obtain surface-modified silicon carbide composite powder.

[0031] As a preferred embodiment, the preparation steps of the silicon carbide composite powder are as follows: by weight, 4-6 parts of polycarbosilane are dispersed in 100-120 parts of xylene, and then 0.12-0.14 parts of KARSTEDT catalyst are added to obtain a precursor solution; 0.04-0.06 parts of carbon nanotubes are dispersed in 100-120 parts of deionized water, and then 4-6 parts of vinyltriethoxysilane and 4-6 parts of hydrochloric acid solution with a mass concentration of 5% are added, and then 100-120 parts of the precursor solution are added and stirred at 50-60°C for 30-40 minutes, allowed to stand and separate into layers, the upper suspension is separated, rotary evaporated, ground, and calcined at high temperature to obtain silicon carbide composite powder.

[0032] As a preferred embodiment, the high-temperature calcination conditions are as follows: placing the furnace in a tube furnace and calcining at 1200~1300℃ for 30~40 minutes under a nitrogen atmosphere.

[0033] As a preferred embodiment, the surface modification step is as follows: by weight, 1-3 parts of dopamine hydrochloride and 0.6-0.8 parts of tris(hydroxymethyl)aminomethane are added to 400-500 parts of deionized water and stirred evenly. After adjusting the pH to 8.2-8.6, 4-6 parts of the silicon carbide composite powder are added. The mixture is stirred at 30-40°C for 8-10 hours, washed with deionized water, and freeze-dried to obtain surface-modified silicon carbide composite powder.

[0034] This invention first adds polycarbosilane to xylene solvent and uses Karstedt catalyst to obtain a precursor solution. Then, the precursor solution is added to a mixture containing carbon nanotubes. Through sol-gel and high-temperature calcination, the polycarbosilane is cracked and converted into silicon carbide, thereby obtaining carbon nanotube-reinforced silicon carbide composite powder. Then, the surface of the powder is modified by the self-polymerization reaction of dopamine hydrochloride in a weakly alkaline environment, and finally, polydopamine-modified silicon carbide composite powder containing carbon nanotubes is obtained.

[0035] As a preferred embodiment, the isocyanate is selected from one or more of diphenylmethane diisocyanate, terephthalic diisocyanate, naphthalene diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

[0036] As a preferred embodiment, the isocyanate is carbodiimide-modified 4,4'-diphenylmethane diisocyanate.

[0037] The carbodiimide-modified 4,4'-diphenylmethane diisocyanate selected in this invention is a light yellow to colorless transparent liquid with low viscosity and good flowability. It is produced by chemically modifying pure diphenylmethane diisocyanate to introduce carbodiimide groups.

[0038] As a preferred embodiment, the coupling agent is selected from one or more of silane coupling agents KH-550, KH-558, and KH-602.

[0039] As a preferred embodiment, the antioxidant is antioxidant 1076 or antioxidant 1010.

[0040] In a second aspect, the present invention provides a high wear-resistant polyurethane coating wheel for the PCB industry prepared by the preparation method described in the first aspect.

[0041] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0042] (1) The polycaprolactone polyol of the present invention has a high crystallization ability and can form microcrystalline regions to act as physical cross-linking points. At the same time, its molecules contain three hydroxyl groups, which form a three-dimensional network structure after reaction, significantly improving the wear resistance and hardness of the material. In addition, the dense cross-linking network can also effectively block the penetration of acids, alkalis and solvents, and enhance chemical resistance.

[0043] (2) In the compound chain extender of the present invention, ethylenediamine can significantly increase the proportion of hard segments in polyurethane, forming a dense network structure to rapidly improve the hardness and wear resistance of the material. The benzene ring and chlorine atom of 4,4'-methylene-bis(2-chloroaniline) provide rigidity and strong intermolecular forces, which can form highly ordered and regular hard segment micro-regions, thereby ensuring good mechanical properties. In addition, the high crosslinking density and aromatic structure interaction brought about by the compound chain extender can more effectively block the penetration and erosion of chemical media and improve the overall acid and alkali resistance.

[0044] (3) In the surface-modified silicon carbide composite powder of the present invention, silicon carbide forms a hard "skeleton" that directly bears friction and shear force to protect the matrix from being worn too quickly. Carbon nanotubes will generate crack bridging and pull-out effects to hinder crack propagation. The two work together to improve the wear resistance of the material. At the same time, the high modulus of carbon nanotubes enables them to effectively transfer external loads to rigid silicon carbide particles, and significantly improve the overall hardness of the material through an effective load transfer mechanism. In addition, the surface modification of polydopamine enables the composite powder to be evenly distributed in the resin matrix and form entanglement with the molecular chain. Through excellent interfacial bonding, micropores are eliminated and density is improved, reducing the penetration channels of corrosive media, thereby significantly increasing the acid and alkali resistance of the material.

[0045] (4) The carbodiimide-modified 4,4'-diphenylmethane diisocyanate of the present invention is conducive to the formation of a three-dimensional network structure with higher cross-linking density. The denser molecular network is directly converted into better dimensional stability and stronger resistance to deformation, which significantly improves the hardness and wear resistance of the material. At the same time, the introduced carbodiimide group has extremely high chemical activity, which can effectively neutralize acidic substances and cut off the autocatalytic cycle in the hydrolysis of polyurethane under acid and alkali conditions, thus achieving good acid and alkali resistance. Detailed Implementation

[0046] 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.

[0047] The sources of some components in the examples and comparative examples are as follows:

[0048] Polycaprolactone polyol PCL303, liquid, with a molecular weight of 300 and a hydroxyl value of 561 mg KOH / g, was purchased from Shenzhen Guanghua Weiye Co., Ltd.

[0049] Polycaprolactone polyol PCL305, liquid, with a molecular weight of 500 and a hydroxyl value of 337 mg KOH / g, was purchased from Shenzhen Guanghua Weiye Co., Ltd.

[0050] Polycaprolactone polyol PCL230, waxy, with a molecular weight of 3000 and a hydroxyl value of 37 mg KOH / g, was purchased from Shenzhen Guanghua Weiye Co., Ltd.

[0051] Polytetrahydrofuran ether polyol, model PTMG1000, purchased from Mitsubishi Chemical, Japan;

[0052] Ethylenediamine, CAS No. 107-15-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0053] 4,4'-Methimine-bis(2-chloroaniline), CAS No. 101-14-4, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0054] Nano silicon carbide powder, item number S140297, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0055] Carbodiimide-modified 4,4'-diphenylmethane diisocyanate, model CDMDI-100H, was purchased from Wanhua Chemical Group Co., Ltd.

[0056] Pure diphenylmethane diisocyanate, model MDI-100, was purchased from Wanhua Chemical Group Co., Ltd.

[0057] Polycarbosilane, CAS No. 62306-27-8, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0058] KARSTEDT catalyst, CAS No. 81032-58-8, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0059] Carbon nanotubes, item number C434647, were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0060] Vinyltriethoxysilane, CAS No. 78-08-0, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0061] Dopamine hydrochloride, CAS No. 62-31-7, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0062] Tris(hydroxymethyl)aminomethane, CAS No. 77-86-1, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0063] Example 1: This example provides a method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry, including the following steps:

[0064] S1. After degreasing and rust removal, the metal shaft core (aluminum alloy material with sandblasted surface) is sandblasted to Ra 8μm, uniformly coated with Chemlock 218 primer, and dried to obtain the pre-treated metal shaft core.

[0065] S2. Place the pretreated metal shaft core in a mold, then add liquid polyurethane to the embedded shaft core, and heat treat at 100°C for 3 hours to form an elastic buffer layer with a thickness of 8mm, thus obtaining a metal shaft core with an elastic buffer layer.

[0066] S3. Mix 80 parts of polycaprolactone triol PCL303 and 40 parts of polytetrahydrofuran ether polyol and dehydrate under vacuum at 120°C for 1 hour. After dehydration, cool down to 80°C, then add 10 parts of ethylenediamine, 5 parts of 4,4'-methylene-bis(2-chloroaniline), 8 parts of functional filler surface-modified silicon carbide composite powder, 1.5 parts of silane coupling agent KH-550, and 0.8 parts of antioxidant 1076 and disperse evenly to obtain component A. Preheat 100 parts of carbodiimide-modified 4,4'-diphenylmethane diisocyanate at 75°C for 10 minutes and mix it with component A. Degas under vacuum to obtain casting material.

[0067] S4. The metal shaft core with elastic buffer layer is cast and molded using the casting material, then cured at 100°C for 2 hours, and after demolding, it is cured at 120°C for 8 hours. Precision grinding is then performed to form a wear-resistant working layer with a thickness of 15mm, resulting in a high wear-resistant polyurethane coating wheel for the PCB industry. The wheel surface roundness of the coating wheel is 0.018mm and the surface roughness is 0.8μm.

[0068] Preparation of the surface-modified silicon carbide composite powder: By weight, 6 parts of polycarbosilane were dispersed in 120 parts of xylene, and then 0.14 parts of KARSTEDT catalyst were added to obtain a precursor solution; 0.06 parts of carbon nanotubes were dispersed in 120 parts of deionized water, and then 6 parts of vinyltriethoxysilane and 6 parts of 5% hydrochloric acid solution were added, followed by 120 parts of the precursor solution. The mixture was stirred at 60°C for 30 min, allowed to stand and separate into layers, the upper suspension was separated, rotary evaporated, ground, and placed in a tube furnace and calcined at 1300°C for 30 min under a nitrogen atmosphere to obtain silicon carbide composite powder; 3 parts of dopamine hydrochloride and 0.8 parts of tris(hydroxymethyl)aminomethane were added to 500 parts of deionized water and stirred evenly. After adjusting the pH to 8.6, 6 parts of the silicon carbide composite powder were added, stirred at 40°C for 8 h, washed with deionized water, and freeze-dried to obtain the surface-modified silicon carbide composite powder.

[0069] Example 2: This example provides a method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry, including the following steps:

[0070] S1. After degreasing and rust removal, the metal shaft core (made of stainless steel with sandblasted surface) is sandblasted to Ra 5μm, and then uniformly coated with Chemlock 218 primer and dried to obtain the pre-treated metal shaft core.

[0071] S2. Place the pretreated metal shaft core in a mold, then add liquid polyurethane to the embedded shaft core, and heat treat at 80°C for 3 hours to form an elastic buffer layer with a thickness of 3mm, thus obtaining a metal shaft core with an elastic buffer layer.

[0072] S3. Mix 60 parts of polycaprolactone triol PCL305 and 20 parts of polytetrahydrofuran ether polyol and dehydrate under vacuum at 100℃ for 2 hours. After dehydration, cool down to 60℃, then add 4 parts of ethylenediamine, 4 parts of 4,4'-methylene-bis(2-chloroaniline), 3 parts of functional filler surface-modified silicon carbide composite powder, 0.5 parts of silane coupling agent KH-558, and 0.3 parts of antioxidant 1010 and disperse evenly to obtain component A. Preheat 80 parts of carbodiimide-modified 4,4'-diphenylmethane diisocyanate at 70℃ for 20 minutes and mix it with component A. Degas under vacuum to obtain casting material.

[0073] S4. The metal shaft core with elastic buffer layer is cast and molded using the castable material, then cured at 90°C for 3 hours, and after demolding, it is cured at 100°C for 9 hours. Precision grinding is then performed to form a wear-resistant working layer with a thickness of 5 mm, resulting in a high wear-resistant polyurethane coating wheel for the PCB industry. The wheel surface roundness of the coating wheel is 0.015 mm, and the surface roughness is 0.5 μm.

[0074] Preparation of the surface-modified silicon carbide composite powder: 4 parts by weight of polycarbosilane were dispersed in 100 parts of xylene, and then 0.12 parts of KARSTEDT catalyst were added to obtain a precursor solution; 0.04 parts of carbon nanotubes were dispersed in 100 parts of deionized water, and then 4 parts of vinyltriethoxysilane and 4 parts of 5% hydrochloric acid solution were added, followed by 100 parts of the precursor solution. The mixture was stirred at 60°C for 30 min, allowed to stand and separate into layers, the upper suspension was separated, rotary evaporated, ground, and placed in a tube furnace and calcined at 1200°C for 40 min under a nitrogen atmosphere to obtain silicon carbide composite powder; 1 part of dopamine hydrochloride and 0.6 parts of tris(hydroxymethyl)aminomethane were added to 400 parts of deionized water and stirred evenly. After adjusting the pH to 8.2, 4 parts of the silicon carbide composite powder were added, stirred at 30°C for 10 h, washed with deionized water, and freeze-dried to obtain the surface-modified silicon carbide composite powder.

[0075] Example 3: This example provides a method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry, including the following steps:

[0076] S1. After degreasing and rust removal, the metal shaft core (aluminum alloy material with sandblasted surface) is sandblasted to Ra 6μm, uniformly coated with Chemlock 218 primer, and dried to obtain the pre-treated metal shaft core.

[0077] S2. Place the pretreated metal shaft core in a mold, then add liquid polyurethane to the embedded shaft core, and heat treat at 90°C for 2 hours to form an elastic buffer layer with a thickness of 5mm, thus obtaining a metal shaft core with an elastic buffer layer.

[0078] S3. Mix 70 parts of polycaprolactone triol PCL305 and 30 parts of polytetrahydrofuran ether polyol and dehydrate under vacuum at 110℃ for 1.5h. After dehydration, cool down to 70℃, then add 6 parts of ethylenediamine, 4 parts of 4,4'-methylene-bis(2-chloroaniline), 5 parts of functional filler surface-modified silicon carbide composite powder, 0.58 parts of silane coupling agent KH-602, and 0.5 parts of antioxidant 1076 and disperse evenly to obtain component A. Preheat 90 parts of carbodiimide-modified 4,4'-diphenylmethane diisocyanate at 72℃ for 15min and mix it with component A. Degas under vacuum to obtain casting material.

[0079] S4. The metal shaft core with elastic buffer layer is cast and molded using the casting material, then cured at 95°C for 2.5 hours, and after demolding, it is cured at 110°C for 8.5 hours. Precision grinding is then performed to form a wear-resistant working layer with a thickness of 10 mm, resulting in a high wear-resistant polyurethane coating wheel for the PCB industry. The wheel surface roundness of the coating wheel is 0.016 mm, and the surface roughness is 0.6 μm.

[0080] Preparation of the surface-modified silicon carbide composite powder: 5 parts by weight of polycarbosilane were dispersed in 110 parts of xylene, and then 0.13 parts of KARSTEDT catalyst were added to obtain a precursor solution; 0.05 parts of carbon nanotubes were dispersed in 110 parts of deionized water, and then 5 parts of vinyltriethoxysilane and 5 parts of hydrochloric acid solution with a mass concentration of 5% were added, followed by 110 parts of the precursor solution. The mixture was stirred at 55°C for 35 min, allowed to stand and separate into layers, the upper suspension was separated, rotary evaporated, ground, and placed in a tube furnace and calcined at 1250°C for 35 min under a nitrogen atmosphere to obtain silicon carbide composite powder; 2 parts of dopamine hydrochloride and 0.7 parts of tris(hydroxymethyl)aminomethane were added to 450 parts of deionized water and stirred evenly. After adjusting the pH to 8.4, 5 parts of the silicon carbide composite powder were added, stirred at 35°C for 9 h, washed with deionized water, and freeze-dried to obtain the surface-modified silicon carbide composite powder.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that polycaprolactone polyol PCL230 is used instead of polycaprolactone polyol PCL303.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that the chain extender was changed to 13 parts ethylenediamine and 2 parts 4,4'-methylene-bis(2-chloroaniline).

[0085] Comparative Example 3

[0086] The difference between this comparative example and Example 1 is that the chain extender was changed to 2 parts ethylenediamine and 13 parts 4,4'-methylene-bis(2-chloroaniline).

[0087] Comparative Example 4

[0088] The difference between this comparative example and Example 1 is that the chain extender was changed to 15 parts of ethylenediamine.

[0089] Comparative Example 5

[0090] The difference between this comparative example and Example 1 is that the chain extender was changed to 15 parts of 4,4'-methimide-bis(2-chloroaniline).

[0091] Comparative Example 6

[0092] The difference between this comparative example and Example 1 is that silicon carbide composite powder is used instead of surface-modified silicon carbide composite powder.

[0093] Comparative Example 7

[0094] The difference between this comparative example and Example 1 is that commercially available nano silicon carbide powder (item number S140297) was used instead of surface-modified silicon carbide composite powder.

[0095] Comparative Example 8

[0096] The difference between this comparative example and Example 1 is that commercially available diphenylmethane diisocyanate (model MDI-100) was used instead of surface-modified silicon carbide composite powder.

[0097] Performance testing

[0098] I. Abrasion resistance test:

[0099] The test was conducted in accordance with the requirements of GB / T 9867-2008 Determination of abrasion resistance of vulcanized rubber or thermoplastic rubber (rotary roller abrasion tester method).

[0100] II. Hardness Test:

[0101] (1) Refer to GB / T 39693.7-2022 Determination of hardness of vulcanized rubber or thermoplastic rubber - Part 7: Determination of apparent hardness of rubber rollers by Shore hardness test and record it as the hardness before treatment;

[0102] (2) First, immerse the coating wheel in a 10% sulfuric acid solution for 60 minutes, and then perform a Shore hardness test. Record the hardness after acid treatment.

[0103] (3) First, immerse the coating wheel in a 10% sodium hydroxide solution for 60 minutes, and then perform a Shore hardness test. Record the hardness after alkali treatment.

[0104] Table 1 Performance Test Results

[0105]

[0106] Compared to Example 1, replacing PCL303 with polycaprolactone polyol PCL230 resulted in increased DIN abrasion, decreased hardness, and worsened acid and alkali resistance due to the excessively large molecular weight and low hydroxyl value of PCL230 (Comparative Example 1). Compared to Example 1, replacing PCL303 with ethylenediamine as the chain extender resulted in increased DIN abrasion, decreased hardness, and worsened acid and alkali resistance due to excessive ethylenediamine leading to poor compounding effect (Comparative Example 1). Comparative Example 2); Compared to Example 1, the chain extender was changed to 2 parts ethylenediamine and 13 parts 4,4'-methylene-bis(2-chloroaniline). Due to the insufficient amount of ethylenediamine, the compounding effect was poor, resulting in increased DIN abrasion, decreased hardness, and worsened acid and alkali resistance of the material (Comparative Example 3); Compared to Example 1, the chain extender was changed to 15 parts ethylenediamine. Lacking the compounding effect of 4,4'-methylene-bis(2-chloroaniline), the DIN abrasion of the material increased, decreased hardness, and worsened acid and alkali resistance (Comparative Example 4); Compared to Example 1, the chain extender was changed to 15 parts of 4,4'-methylene-bis(2-chloroaniline), lacking the compounding effect of ethylenediamine, resulting in increased DIN abrasion, decreased hardness, and worsened acid and alkali resistance of the material (Comparative Example 5); compared to Example 1, silicon carbide composite powder was used instead of surface-modified silicon carbide composite powder, lacking the surface modification of dopamine hydrochloride, resulting in increased DIN abrasion, decreased hardness, and worsened acid and alkali resistance of the material (Comparative Example 6); compared to Example 1, commercially available nano silicon carbide powder (product number S) was used. 140297) Replacing surface-modified silicon carbide composite powder with the surface-modified silicon carbide composite powder resulted in increased DIN wear, decreased hardness, and worsened acid and alkali resistance of the material (Comparative Example 7); Compared with Example 1, using commercially available diphenylmethane diisocyanate (model MDI-100) to replace surface-modified silicon carbide composite powder resulted in increased DIN wear, decreased hardness, and worsened acid and alkali resistance of the material (Comparative Example 8).

Claims

1. A method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry, characterized in that, Includes the following steps: S1. Pre-treat the metal shaft core to obtain the pre-treated metal shaft core; S2. Place the pretreated metal shaft core in a mold, then add liquid polyurethane to embed the shaft core, and heat treat to form an elastic buffer layer to obtain a metal shaft core with an elastic buffer layer. S3. Polycaprolactone polyol and polytetrahydrofuran ether polyol are mixed and then vacuum dehydrated. Then, chain extender, functional filler, coupling agent and antioxidant are added and dispersed evenly to obtain component A. Isocyanate is preheated and mixed with component A and stirred evenly. Vacuum degassing is then performed to obtain casting material. The polycaprolactone polyol is a polycaprolactone triol with a molecular weight of 200-600 and a hydroxyl value of 300-600 mg KOH / g. The functional filler is a surface-modified silicon carbide composite powder; The preparation method of the surface-modified silicon carbide composite powder is as follows: silicon carbide composite powder is prepared using polycarbosilane and carbon nanotubes as raw materials, and then the surface of the silicon carbide composite powder is modified using dopamine hydrochloride to obtain surface-modified silicon carbide composite powder. The preparation steps of the silicon carbide composite powder are as follows: by weight, 4-6 parts of polycarbosilane are dispersed in 100-120 parts of xylene, and then 0.12-0.14 parts of KARSTEDT catalyst are added to obtain a precursor solution; 0.04-0.06 parts of carbon nanotubes are dispersed in 100-120 parts of deionized water, and then 4-6 parts of vinyltriethoxysilane and 4-6 parts of hydrochloric acid solution with a mass concentration of 5% are added, and then 100-120 parts of the precursor solution are added and stirred at 50-60°C for 30-40 min, allowed to stand and separate into layers, the upper suspension is separated, rotary evaporated, ground, and calcined at high temperature to obtain silicon carbide composite powder; S4. The metal shaft core with elastic buffer layer is cast and molded using the castable material, thermoformed, and precision machined to form a wear-resistant working layer, thereby obtaining a high wear-resistant polyurethane coated wheel for the PCB industry.

2. The method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry according to claim 1, characterized in that, The components, by weight, include: 60-80 parts of polycaprolactone polyol, 20-40 parts of polytetrahydrofuran ether polyol, 8-15 parts of chain extender, 3-8 parts of functional filler, 0.5-1.5 parts of coupling agent, 0.3-0.8 parts of antioxidant, and 80-100 parts of isocyanate.

3. The method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry according to claim 1, characterized in that, The chain extender is ethylenediamine and 4,4'-methylenebis(2-chloroaniline); The mass ratio of ethylenediamine to 4,4'-methylene-bis(2-chloroaniline) in the chain extender is (1~2):

1.

4. The method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry according to claim 1, characterized in that, The surface modification steps are as follows: by weight, 1-3 parts of dopamine hydrochloride and 0.6-0.8 parts of tris(hydroxymethyl)aminomethane are added to 400-500 parts of deionized water and stirred evenly. After adjusting the pH to 8.2-8.6, 4-6 parts of the silicon carbide composite powder are added. The mixture is stirred at 30-40°C for 8-10 hours, washed with deionized water, and freeze-dried to obtain surface-modified silicon carbide composite powder.

5. The method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry according to claim 1, characterized in that, The isocyanate is selected from one or more of diphenylmethane diisocyanate, terephthalic diisocyanate, naphthalene diisocyanate, toluene diisocyanate, and isophorone diisocyanate.

6. The method for preparing a high-wear-resistant polyurethane coating wheel for the PCB industry according to claim 5, characterized in that, The isocyanate is carbodiimide-modified 4,4'-diphenylmethane diisocyanate.

7. A high-wear-resistant polyurethane coating wheel for the PCB industry, characterized in that, It is prepared according to any one of claims 1-6.

Images