Low-carbon two-component polyurethane pouring sealant for circuit board and preparation method of low-carbon two-component polyurethane pouring sealant

Abstract

The invention relates to the field of electric appliance potting materials, in particular to a low-carbon two-component polyurethane potting adhesive for a circuit board and a preparation method of the low-carbon two-component polyurethane potting adhesive. The preparation raw materials of the low-carbon double-component polyurethane pouring sealant for the circuit board comprise a component A and a component B, wherein the component A is prepared from the following raw materials: isocyanate, a flame retardant and a plasticizer; and the component B is prepared from the following raw materials: PCE, castor oil, a hydrophobic acrylate oligomer, a catalyst and a defoaming agent. The PCE and the castor oil are used as core raw materials, and the low-carbon and environment-friendly characteristics are achieved; by introducing the hydrophobic acrylate oligomer and combining the structural advantages of PCE, the water absorption rate of the product is remarkably reduced, meanwhile, the product has balanced mechanical properties and excellent aging resistance, the pouring sealant can effectively protect a circuit board from being affected by environments such as moisture and high temperature, and the actual use effect is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical appliance potting materials, in particular to a low-carbon two-component polyurethane potting adhesive for circuit boards and a preparation method thereof. BACKGROUND

[0002] In the context of rapid iteration of electronic devices, as a core component, the working environment of circuit boards is increasingly complex, facing multiple challenges such as moisture, high temperature, chemical corrosion, etc., and strict requirements are put forward for the performance of protective materials. As a key material for protecting circuit boards, potting adhesive needs to have good sealing, insulation, aging resistance and other properties to ensure the stable operation of circuit boards in complex environments, so the research and development of high-performance potting adhesive has become an important direction in the field of electronic materials.

[0003] Traditional polyurethane circuit board potting adhesives are mostly prepared using castor oil and polyether as main raw materials. Such materials have obvious shortcomings in actual application. On the one hand, the production process of traditional raw materials has high carbon emissions, which is not consistent with the current global concept of low-carbon environmental protection; on the other hand, their hydrophobic performance is insufficient, leading to problems such as short circuit, performance degradation, etc. of the circuit board after potting due to moisture absorption, and poor aging resistance, which easily leads to phenomena such as hardness decrease and cracking in long-term use or high-temperature environment, making it difficult to meet the long-term protection needs of high-end electronic devices.

[0004] Therefore, it has become a technical problem to be solved in the field to develop a circuit board potting adhesive that is low-carbon, low-water absorption, has excellent aging resistance, and has a safe and controllable preparation process. SUMMARY

[0005] To solve the above technical problems, the present application provides a low-carbon two-component polyurethane potting adhesive for circuit boards, which is prepared from A component and B component. The preparation raw materials of the A component include, by mass fraction, 25-35 parts of isocyanate, 10-15 parts of flame retardant, and 8-15 parts of plasticizer. The preparation raw materials of the B component include, by mass fraction, 10-40 parts of PCE (carbon dioxide-based polycarbonate polyol), 20-80 parts of bio-based polyol, 10-40 parts of hydrophobic acrylate oligomer, 0-10 parts of plasticizer, 0.01-0.05 parts of catalyst, and 0.02-0.1 parts of defoaming agent; the viscosity of the hydrophobic acrylate oligomer at 25°C is 10000±2000 mPa·s, and the hydroxyl value is 60-180 mgKOH / g; more preferably, the hydroxyl value is 120±5 mgKOH / g.

[0006] As an implementable case, the mass ratio of the A component to the B component is 1: (1-5).

[0007] As an implementable case, the bio-based polyol includes at least one of castor oil, modified castor oil polyol, and modified soybean oil polyol.

[0008] As an implementable case, the isocyanate includes one or more of MDI (4,4'-diphenylmethane diisocyanate), TDI (toluene diisocyanate), HDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), or hydrogenated MDI.

[0009] Further, the isocyanate is MDI, and the MDI is liquid MDI.

[0010] As an implementable case, the flame retardant includes a phosphate ester flame retardant.

[0011] Further, the phosphate ester flame retardant includes one or more of tricresyl phosphate, triphenyl phosphate, phenyldiphenyl phosphate, triethyl phosphate, or tris (2-chloropropyl) phosphate.

[0012] As an implementable case, the plasticizer includes one or more of dioctyl terephthalate, diisononyl cyclohexane-1,2-dicarboxylate, tributyl citrate, acetyl tributyl citrate, trioctyl trimellitate, polyol benzoate, di-n-octyl isosorbide, dioctyl adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, or epoxidized soybean oil.

[0013] As an implementable case, the PCE has a viscosity of 10,000-20,000 mPa·s at 40°C and a viscosity of 1,000-3,000 mPa·s at 70°C.

[0014] As an implementable case, the PCE has a hydroxyl value of 51-61 mgKOH / g.

[0015] Further, the PCE has a grade of PCE-330P, which can be purchased from Hefei Plas Advanced Materials Technology Co., Ltd.

[0016] This invention selects PCE with a viscosity of 10000-20000 mPa·s at 40℃ to meet the requirements of both flowability and anti-drip properties in two-component potting compounds. This viscosity range avoids the problems of material stratification, adhesive loss during potting, and difficulty in removing air bubbles caused by excessive flow of PCE in component B when the viscosity is too low. It also solves the problem of excessively high overall viscosity of component B, creating mixing dead zones and affecting the sufficiency of the curing reaction and the uniformity of the product's mechanical properties when the viscosity is too high. This ensures that the castor oil, hydrophobic acrylate oligomers, plasticizers, and other raw materials in component B can be quickly fused during stirring and heating, and that the mixture of components A and B has the application flowability suitable for continuous operation of the dispensing machine, ensuring that the adhesive evenly covers the surface and gaps of the circuit board. The selection of PCE with a hydroxyl value of 51-61 mgKOH / g allows for the control of the crosslinking density of the polyurethane curing reaction. This hydroxyl value range avoids the problems of hydroxyl values ​​below 51 mgKOH / g. Insufficient hydroxyl groups at a hydroxyl value of mgKOH / g result in low crosslinking density, insufficient tensile strength, and low hardness. This also prevents excessive hydroxyl groups at a hydroxyl value higher than 61 mgKOH / g from causing excessive crosslinking density, embrittlement, and decreased elongation at break. This allows PCE and liquefied MDI to form a moderately crosslinked polyurethane network, resulting in excellent mechanical properties that balance elasticity and rigidity, meeting the requirements for circuit board protection. On the other hand, it can synergistically improve the product's aging resistance and hydrolysis resistance. Since PCE is a random block copolymer of polycarbonate and polyether, this hydroxyl value range allows for a more uniform distribution of molecular chain length and functionality. After curing, it forms a regular polyurethane network structure, which fully utilizes the high hydrogen bond density of carbonate bonds to improve weather resistance and reduces water molecule penetration channels. Combined with hydrophobic acrylate oligomers, it significantly reduces the product's water absorption rate. At the same time, the moderate crosslinking density avoids excessive crowding of molecular chains and retains the flexibility of ether bonds, allowing the product to maintain high hardness even after accelerated aging at 143℃ for 8 hours.

[0017] As an feasible example, the raw materials for preparing the hydrophobic acrylate oligomer include, by mass parts, 1-10 parts initiator, 50-150 parts acrylate monomer and 100-200 parts solvent.

[0018] Furthermore, the acrylate monomers include long-chain alkyl acrylates and hydroxyalkyl acrylates; the long-chain alkyl acrylates include at least one of dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, 2-hexyldecyl acrylate, 2-octyldodecyl acrylate, 2-decyltetradecyl acrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, and octadecyl methacrylate; the hydroxyalkyl acrylates include at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate.

[0019] Furthermore, the solvent includes one of n-propanol, isopropanol, methyl ethyl ketone, or ethyl acetate.

[0020] Furthermore, the initiator includes one or more of the following: benzoyl peroxide (BPO), dilauroyl peroxide, diacetyl peroxide, dipropionyl peroxide, dibutyryl peroxide, di(2,4-dichlorobenzoyl peroxide), di(o-methylbenzoyl peroxide), di(p-chlorobenzoyl peroxide), tert-butyl peroxypentanoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanate, di(1-hydroxycyclohexyl peroxide), methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate, dimyristyl peroxydicarbonate, cyclohexanone peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, azobisisobutyronitrile, and azobisisovalerate.

[0021] As an implementable example, the method for preparing the hydrophobic acrylate oligomer includes: Mix 50-80% of the total solvent, 15-40% of the total acrylate monomer, and 15-40% of the total initiator, and heat to 60-90℃ to initiate polymerization to obtain the base material; Mix the remaining solvent, remaining acrylate monomer and remaining initiator, and add them dropwise to the substrate for polymerization. The addition time is 1-2 hours. After the addition is completed, keep the reaction at 60-90℃ for 1-2 hours, cool down, and remove the solvent under reduced pressure to obtain hydrophobic acrylate oligomer.

[0022] PCE, as a random block copolymer of polycarbonate and polyether, combines the rigidity of carbonate bonds with the flexibility of ether bonds. It contains trifunctional hydroxyl groups, which can form high-density crosslinking nodes with liquefied MDI component A. The hydrophobic acrylate oligomer is a linear polymer with long-chain alkyl side chains, which is highly hydrophobic and reactive. Its hydroxyl value can reach 120±5mgKOH / g. Its molecular chains can interpenetrate in the crosslinking network formed by PCE, fill the network gaps, and reduce molecular chain aggregation through the steric hindrance effect of long carbon chains. At the same time, the low hydroxyl value of PCE avoids excessive crosslinking embrittlement, and the higher hydroxyl value of the oligomer supplements the crosslinking sites. The two work together to keep the crosslinking density of the polyurethane network in a moderate range, which ensures the structural strength of the potting compound and retains sufficient elasticity, thus solving the contradiction of "rigidity and elasticity cannot be obtained at the same time" in traditional systems. Simultaneously, the long-chain alkyl groups of the hydrophobic acrylate oligomer form a physical hydrophobic barrier, while PCE, due to the absence of alkyd polyester bonds and the high hydrogen bond density of carbonate bonds, results in a more regular polymer network structure, forming chemical barrier channels. The combination of these two factors drastically reduces water absorption. Furthermore, the hydrolysis resistance of PCE and the moisture resistance of the oligomer work synergistically to enhance the structural stability of the potting compound in humid and hot environments, preventing short circuits and corrosion of the circuit board due to moisture absorption. At the same time, the strong cohesiveness of PCE improves the tensile strength, tear strength, and hardness of the potting compound, providing structural support. The long-chain alkyl groups of the hydrophobic acrylate oligomer enhance the molecular chain slippage ability, improving the elongation at break and resistance to deformation, allowing the potting compound to meet the requirements of impact resistance and adaptability to slight deformation. In addition, PCE has an initial thermal decomposition temperature higher than 200℃ and strong weather resistance of carbonate bonds, which can resist high-temperature oxidation. The long-chain alkyl groups of the hydrophobic acrylate oligomer have a stable structure and no thiol polymerization inhibitor residues, preventing molecular chain degradation during aging. The synergy of these two factors allows the potting compound to maintain high hardness even after accelerated aging at 143℃ for 8 hours, significantly improving its service life under high-temperature environments.

[0023] As an implementable example, the catalyst comprises at least one of dibutyltin dilaurate, dibutyltin diacetate, stannous octanoate, bismuth neodecanoate, bismuth octanoate, bismuth isooctanoate, bismuth naphthenate, bismuth laurate, zinc octanoate, zinc isooctanoate, zinc neodecanoate, zinc naphthenate, or zinc laurate.

[0024] A second aspect of this invention provides a method for preparing a low-carbon two-component polyurethane potting compound for circuit boards, comprising the following steps: The plasticizer and flame retardant are mixed, heated to 100~120℃, stirred, and then dehydrated under vacuum at -0.09~-0.095MPa. The mixture is cooled to below 60℃, isocyanate is added, stirred evenly, and then cooled to 40~45℃. The mixture is filtered to obtain component A. PCE, bio-based polyol, hydrophobic acrylate oligomer, and plasticizer are mixed, heated to 100~120℃, stirred, and then dehydrated under vacuum at -0.09~-0.095MPa. The mixture is then cooled to below 60℃, defoamer and catalyst are added, stirred evenly, cooled to 40~45℃, filtered, and discharged to obtain component B. When using, simply mix and apply the A and B components of the low-carbon two-component polyurethane potting compound to the circuit board in the specified proportions.

[0025] Beneficial effects (i) This invention uses PCE, bio-based polyols and hydrophobic acrylate oligomers as core raw materials. Each kilogram of PCE contains 20-35% carbon dioxide by mass, realizing the resource utilization of carbon dioxide and conforming to the concept of carbon reduction. The raw materials do not contain high carbon pollutants, and the synthesis process of hydrophobic acrylate oligomers does not leave any thiol polymerization inhibitors, and there is no irritating odor. Its environmental friendliness is better than that of the traditional castor oil / polyether system.

[0026] (II) By adding self-made hydrophobic acrylate oligomers and combining them with the regular polymer network structure of PCE, the present invention forms a dual hydrophobic barrier of physical and chemical properties, which significantly reduces the water absorption rate of the product to a minimum of only 0.025%, which is far superior to the traditional system. It can effectively avoid short circuits and corrosion problems caused by moisture absorption of circuit boards, and greatly improve the reliability of protection.

[0027] (III) The synergistic effect of PCE and hydrophobic acrylate oligomers enables the potting compound to maintain appropriate hardness while increasing the elongation at break to 88.4%-116.9% and the tensile strength to be stable at 0.62-0.91MPa. This balances the impact-resistant structural support with the elasticity required to accommodate slight deformation of the circuit board, thus resolving the contradiction between rigidity and elasticity in traditional systems.

[0028] (iv) Based on the initial thermal decomposition temperature of PCE above 200℃ and the high weather resistance of carbonate bonds, combined with structurally stable hydrophobic acrylate oligomers, the product can still maintain high hardness after accelerated aging at 143℃ for 8 hours, which is far superior to the traditional system. It can adapt to complex environments such as high temperature and humid heat, and extend the service life of circuit boards.

[0029] (v) The hydrophobic acrylate oligomer synthesis process in this invention is simple, the molecular weight is controllable, the viscosity is stable, and the viscosity is highly compatible with raw materials such as PCE and bio-based polyols. At the same time, the production processes of components A and B are mature, no special equipment is required, and after mixing, they can be adapted to continuous operation of dispensing machines. The curing process is stable, the product performance has good batch consistency, and it is suitable for large-scale production applications. Detailed Implementation

[0030] In Examples 1-6 and Comparative Examples 1-2 of this invention, two types of component A are mainly used, namely component A1 and component A2.

[0031] The raw materials for preparing component A1, by weight, include 30 parts liquefied MDI, 12 parts flame retardant, and 8 parts epoxidized soybean oil (plasticizer). The raw materials for preparing component A2, by weight, include 27 parts liquefied MDI, 12 parts flame retardant, and 11 parts epoxidized soybean oil (plasticizer). The liquefied MDI was purchased from Wanhua Chemical, model MDI-100LL. The flame retardant is tricresyl phosphate, purchased from Zhejiang Wansheng Co., Ltd.

[0032] Examples 1-4 and Comparative Examples 1-2 used component A1; Examples 5-6 used component A2.

[0033] For component B in Examples 1-6 and Comparative Examples 1-2, the specific information on the raw materials used for preparation and the mass fractions are shown in Table 1.

[0034] Table 1

[0035] The PCE in question is grade PCE-330P, with a viscosity of 1000-3000 mPa·s at 70°C and a hydroxyl value of 51-61 mg KOH / g. It was purchased from Hefei Puli Advanced Materials Technology Co., Ltd.

[0036] The castor oil mentioned is commercially available refined grade 1 castor oil.

[0037] The plasticizer is epoxidized soybean oil, purchased from Tongxiang Chemical Co., Ltd.

[0038] The polyether polyol is designated as polyether PPG-310 and was purchased from Shandong Lanxing Dongda Chemical Co., Ltd.

[0039] The defoamer is brand name BYK-A535 and was purchased from BYK Chemical.

[0040] The catalyst is dibutyltin dilaurate.

[0041] Examples 1-6 and Comparative Examples 1-2 of this invention use two kinds of hydrophobic acrylate oligomers, namely hydrophobic acrylate oligomer 1# and hydrophobic acrylate oligomer 2#.

[0042] The preparation method of the hydrophobic acrylate oligomer 1# is as follows: S1. Mix 100g of isopropanol, 15g of dodecyl acrylate, 5g of hydroxyethyl acrylate, and 1g of BPO, and heat to 80~85℃ to initiate polymerization to obtain the base material; S2. Weigh 50g of isopropanol, 60g of dodecyl acrylate, 20g of hydroxyethyl acrylate, and 4g of BPO. Mix and dissolve them evenly. Add the mixture dropwise after the product base material from step S1 has been initiated. The addition should be completed in 1.5 hours. S3, keep the reaction at 80±2℃ for 1.5h, then cool down to 60℃; S4. The solvent was removed under reduced pressure at 50~60℃ and -0.09~-0.095MPa to obtain hydrophobic acrylate oligomer 1#.

[0043] The viscosity (25℃) of hydrophobic acrylate oligomer 1# is 10000±2000mPa·s, the hydroxyl value is 120±5mgKOH / g, and the product has no monomer odor.

[0044] The preparation method of the hydrophobic acrylate oligomer 2# is as follows: S1. Mix 100g of isopropanol, 10g of dodecyl acrylate, 5g of octadecyl acrylate, 5g of hydroxyethyl acrylate, and 1g of BPO, and heat to 80~85℃ to initiate polymerization to obtain the base material; S2. Weigh 50g of isopropanol, 40g of dodecyl acrylate, 20g of octadecyl acrylate, 20g of hydroxyethyl acrylate, and 4g of BPO. Mix and dissolve them evenly. Add the mixture dropwise after the product base material from step S1 has been initiated. The addition should be completed in 1.5 hours. S3, keep the reaction at 80±2℃ for 1.5h, then cool down to 60℃; S4. The solvent was removed under reduced pressure at 50~60℃ and -0.09~-0.095MPa to obtain hydrophobic acrylate oligomer 2#.

[0045] The viscosity (25℃) of hydrophobic acrylate oligomer 2# is 10000±2000mPa·s, the hydroxyl value is 120±5mgKOH / g, and the product has no monomer odor.

[0046] The preparation method of the hydrophobic potting compound in Examples 1-6 is as follows: 1) Mix tricresyl phosphate and epoxidized soybean oil, heat to 120°C, remove water under vacuum at -0.095 MPa, cool to below 60°C, add liquefied MDI, stir evenly, cool to 45°C, filter and discharge to obtain component A; 2) Mix PCE, castor oil, hydrophobic acrylate oligomer, and plasticizer (if any), heat to 120°C, remove water under vacuum at -0.095 MPa, cool to below 60°C, add defoamer and dibutyltin dilaurate, stir evenly, cool to 45°C, filter and discharge to obtain component B.

[0047] The preparation method of component A of the hydrophobic potting compound in Comparative Example 1 is the same as that in Examples 1-6, while the preparation method of component B is as follows: Castor oil and plasticizer epoxidized soybean oil are mixed, heated to 120°C, stirred, and then dehydrated under vacuum at -0.09 MPa. The mixture is then cooled to below 60°C, and defoamer and dibutyltin dilaurate are added. After stirring evenly, the mixture is cooled to 45°C, filtered, and discharged to obtain component B.

[0048] The preparation method of component A of the hydrophobic potting compound in Comparative Example 2 is the same as that in Examples 1-6, while the preparation method of component B is as follows: Polyether polyol PPG-310 and plasticizer epoxidized soybean oil were mixed, heated to 120°C, and dehydrated under vacuum at -0.095 MPa. The mixture was then cooled to below 60°C, and defoamer and dibutyltin dilaurate were added. After stirring evenly, the mixture was cooled to 45°C and filtered to obtain component B.

[0049] Performance Evaluation Curing conditions: Mix components A and B evenly (mass ratio of components A to B is 1:2), and cure at room temperature (23±2℃) for 7 days.

[0050] 1. Tensile test: The potting compounds prepared according to national standard GB / T 1040.3-2006 were tested in Examples 1-6 and Comparative Examples 1-2.

[0051] 2. Hardness test: The potting compounds prepared according to national standard GB / T531.1-2008 were tested in Examples 1-6 and Comparative Examples 1-2.

[0052] 3. Water absorption rate test The potting compound cured blocks prepared in Examples 1-6 and Comparative Examples 1-2 were immersed in water at 23±2℃ for 24 hours, then removed, dried, and weighed. The weight increase rate was calculated, which is the water absorption rate.

[0053] 4. Accelerated aging test at 143℃ Mix components A and B of the potting compound corresponding to Examples 1-6 and Comparative Examples 1-2 evenly, pour the mixture into a mold with a thickness of 10 mm and a diameter of 50 mm, cure at room temperature of 23±2℃ for 7 days, and then place the sample under saturated water vapor pressure at 143℃ for 8 hours and observe and record the Shore hardness (A).

[0054] The experimental results of the above tests are detailed in Table 2.

[0055] Table 2

[0056] The test results in Table 2 show that as the amount of hydrophobic acrylate oligomer added increases, the water absorption rate of the product decreases significantly, and the potting compound can better protect the circuit after use. Among them, hydrophobic acrylate oligomer #2 has a better effect, which may be because the carbon chain in the raw material octadecyl acrylate is longer and has a better hydrophobic effect.

[0057] After introducing PCE and hydrophobic acrylate oligomers into the formulation, the elasticity of the product was significantly improved, while the hardness did not change much. The results of the 8-hour accelerated aging test showed that after introducing PCE and hydrophobic acrylate oligomers, the potting compounds of Examples 1-6 maintained a high hardness after accelerated aging and had better aging resistance than Comparative Examples 1-2.

Claims

1. A low-carbon two-component polyurethane potting compound for circuit boards, characterized in that, The raw materials for preparation include component A and component B; The raw materials for preparing component A include isocyanate, flame retardant, and plasticizer; The raw materials for preparing component B include carbon dioxide-based polycarbonate polyol PCE, bio-based polyol, hydrophobic acrylate oligomer, catalyst, and defoamer. The mass ratio of component A to component B is 1:(1-5); The hydrophobic acrylate oligomer has a viscosity of 10000±2000 mPa·s at 25°C and a hydroxyl value of 60-180 mgKOH / g. The raw materials for preparing hydrophobic acrylate oligomers, by mass parts, include 1-10 parts initiator, 50-150 parts acrylate monomer and 100-200 parts solvent; The acrylate monomers include long-chain alkyl acrylates and hydroxyalkyl acrylates. The long-chain alkyl acrylates include at least one of dodecyl acrylate, tetradecyl acrylate, hexadecyl acrylate, octadecyl acrylate, 2-hexyldecyl acrylate, 2-octyldodecyl acrylate, 2-decyltetradecyl acrylate, dodecyl methacrylate, tetradecyl methacrylate, hexadecyl methacrylate, and octadecyl methacrylate. The hydroxyalkyl acrylates include at least one of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate.

2. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 1, characterized in that, The raw materials for preparing component B also include plasticizers; The plasticizer includes one or more of the following: dioctyl terephthalate, diisononyl cyclohexane-1,2-dicarboxylate, tributyl citrate, acetylated tributyl citrate, trioctyl trimellitate, polyol benzoate, isosorbide di-n-octyl ester, dioctyl adipate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, or epoxidized soybean oil.

3. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 1, characterized in that, The bio-based polyols include at least one of castor oil, modified castor oil polyols, and modified soybean oil polyols.

4. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 1, characterized in that, The viscosity of the PCE at 70°C is 1000-3000 mPa·s.

5. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 4, characterized in that, The hydroxyl value of the PCE is 51-61 mg KOH / g.

6. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 1, characterized in that, The method for preparing the hydrophobic acrylate oligomer includes: Mix 50-80% of the total solvent, 15-40% of the total acrylate monomer, and 15-40% of the total initiator, and heat to initiate polymerization to obtain the base material; Mix the remaining solvent, remaining acrylate monomer and remaining initiator, and add them dropwise to the substrate to carry out the polymerization reaction. The addition time is 1-2 hours. After the addition is completed, keep the reaction at a constant temperature for 1-2 hours, cool down, and remove the solvent under reduced pressure to obtain the hydrophobic acrylate oligomer.

7. The low-carbon two-component polyurethane potting compound for circuit boards according to claim 6, characterized in that, The polymerization reaction is carried out at a temperature of 60-90℃.

8. A method for preparing a low-carbon two-component polyurethane potting compound for circuit boards according to any one of claims 2-7, characterized in that, Includes the following steps: The plasticizer and flame retardant are mixed and heated to 100~120℃. The mixture is then dehydrated under vacuum at -0.09~-0.095MPa, cooled to below 60℃, and isocyanate is added. After stirring evenly, the mixture is cooled to 40~45℃, filtered, and discharged to obtain component A. PCE, bio-based polyol, hydrophobic acrylate oligomer, and plasticizer are mixed and heated to 100~120℃. The mixture is then vacuum dehydrated at -0.09~-0.095MPa, cooled to below 60℃, and defoamer and catalyst are added. After stirring evenly, the mixture is cooled to 40~45℃, filtered, and discharged to obtain component B.

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