Preparation method of two-component polyurethane pouring sealant for filter

Abstract

The invention relates to the technical field of polyurethane, in particular to a preparation method of a two-component polyurethane pouring sealant for a filter. Comprising a component A and a component B, the component A comprises polymerized MDI and a plasticizer, and the component B comprises, by weight, 3-5 parts of castor oil, 5-20 parts of polyether polyol, 10-30 parts of an acrylate oligomer, 40-60 parts of a filler, 5-10 parts of a molecular sieve, 1-5 parts of color paste and 0.01-0.5 part of an auxiliary agent. The pouring sealant prepared by compounding the castor oil, the polyether polyol and the acrylate oligomer according to a specific ratio has excellent tensile strength, shear strength and high-temperature aging resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of polyurethane, in particular to a preparation method of a two-component polyurethane pouring sealant for filters. BACKGROUND

[0002] With the rapid development of industrial manufacturing and environmental protection technology, high-efficiency air filters are increasingly widely applied in the fields of medical purification, electronic workshops and automobile manufacturing. The core function of the filter depends on reliable adhesion and sealing of the filter paper and the metal frame, and the performance of the polyurethane pouring sealant as a key packaging material directly determines the sealing performance, structural stability and service life of the filter. The polyurethane pouring sealant with high adhesion strength, excellent fluidity and environmental resistance gradually becomes the preferred material in the industry. The polyurethane pouring sealant is generated by the reaction of polyol and isocyanate prepolymer, and the molecular structure of the polyurethane pouring sealant endows the material with unique elasticity and controllable mechanical properties. In the application of the filter, the material needs to meet the strong adhesion of metals, plastics and filter paper and other materials to resist air flow impact and mechanical vibration. In addition, the filter is often exposed to high-temperature environments in industrial scenarios, and the pouring sealant is required to have long-term aging resistance.

[0003] Chinese patent CN116656306B discloses a polyurethane pouring sealant, which comprises an A component and a B component; the A component comprises castor oil, a first polyether polyol, a second polyether polyol, a mixed additive, and aluminum hydroxide; the B component comprises polymeric MDI; and the mixed additive is a mixture of a wet dispersant, a viscosity reducer and a defoaming agent. The polyurethane pouring sealant disclosed in the application solves the problem of the decrease in shear strength caused by the defoaming performance of the pouring sealant on the market, but the shear strength still needs to be improved. SUMMARY

[0004] The first aspect of the application provides a two-component polyurethane pouring sealant for filters, which comprises an A component and a B component, the A component comprises polymeric MDI and a plasticizer, and the B component comprises, by weight, castor oil 3-5 parts, polyether polyol 5-20 parts, acrylic ester oligomer 10-30 parts, filler 40-60 parts, molecular sieve 5-10 parts, color paste 1-5 parts, and additive 0.01-0.5 parts.

[0005] The present inventors have found that by compounding castor oil, polyether polyol and acrylic ester oligomer in a specific ratio, a pouring sealant is prepared, which has excellent tensile strength, shear strength and high temperature aging performance. Through the basic crosslinking of castor oil, the flexibility adjustment of polyether polyol, the rigidity strengthening of acrylic ester oligomer, and the auxiliary action of fillers and molecular sieves, a hard segment-soft segment microphase separation structure with high crosslinking density but uniform distribution is formed. This structure exhibits high strength and high hardness at room temperature, and can still maintain a Shore A hardness of 50 or more when high temperature aging due to the presence of hydrophobicity and stable chemical bonds, thereby meeting the long-term use requirements of filters under complex working conditions.

[0006] The weight ratio of the polymeric MDI and the plasticizer is 1:(0.8-1.5).

[0007] The polyether polyol includes at least one of the following brand products of Shandong Longhua New Material Co., Ltd.: LE-310, LE-204, LE-210A, LE-305, and LE-310.

[0008] Optionally, the weight ratio of the castor oil, the polyether polyol and the acrylic ester oligomer is 1:(1-3):(4-10).

[0009] Optionally, the weight ratio of the castor oil, the polyether polyol and the acrylic ester oligomer is 1:(1-2.5):(6-10).

[0010] Optionally, the weight ratio of the castor oil, the polyether polyol and the acrylic ester oligomer is 1:(2-2.5):(8-10).

[0011] Optionally, the weight ratio of the castor oil, the polyether polyol and the acrylic ester oligomer is 3:7:30.

[0012] The content of isocyanate groups in the polymeric MDI is 28-35wt%.

[0013] Optionally, the content of isocyanate groups in the polymeric MDI is 28-32wt%.

[0014] The hydroxyl value of the acrylic ester oligomer is 90-160mgKOH / g.

[0015] Optionally, the hydroxyl value of the acrylic ester oligomer is 90-120mgKOH / g.

[0016] The raw materials for preparing the acrylic ester oligomer include alkyl acrylate monomers and hydroxyalkyl acrylate monomers.

[0017] The hydroxyalkyl acrylate monomer includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

[0018] The alkyl acrylate monomer includes at least one of ethyl acrylate, butyl acrylate, isooctyl acrylate, isopropyl acrylate, lauryl acrylate, and isobutyl acrylate.

[0019] The raw material for preparing the acrylate oligomer further includes a solvent and an initiator.

[0020] The auxiliary includes at least one of a catalyst, a plasticizer, and an antifoaming agent.

[0021] Optionally, the initiator includes at least one of, but is not limited to, BPO (benzoyl peroxide), AIBN (azobisisobutyronitrile), TBPB (tert-butyl peroxybenzoate), DCP (dicumyl peroxide), or di-tert-butyl peroxide.

[0022] Optionally, the solvent includes at least one of, but is not limited to, isopropyl alcohol, ethanol, methanol, and butyl acetate.

[0023] Optionally, the auxiliary includes a catalyst and an antifoaming agent.

[0024] Optionally, the plasticizer includes at least one of, but is not limited to, DOP (dioctyl phthalate), DOA (dioctyl adipate), DINP (diisononyl phthalate), and epoxidized soybean oil.

[0025] Optionally, the antifoaming agent includes at least one of, but is not limited to, the following brands: BYK-2735, BYK-052, BYK-024, BYK-057, and BYK-065.

[0026] Optionally, the catalyst includes at least one of, but is not limited to, dibutyltin dilaurate, dibutyltin diacetate, dimethyltin dioctoate, dibutyltin maleate, dioctyltin dilaurate, and bis(trioctyltin) oxide.

[0027] Optionally, the raw material for preparing the acrylate oligomer includes, by weight, 70-80 parts of butyl acrylate, 20-30 parts of a hydroxy acrylate monomer, 3-8 parts of an initiator, and 100-200 parts of a solvent.

[0028] The preparation method of the acrylate oligomer comprises the following steps: uniformly mixing 10-40% of butyl acrylate in total butyl acrylate, 10-40% of hydroxy acrylate monomer in total hydroxy acrylate monomer and 10-40% of initiator in total initiator with a solvent to obtain a first mixture; uniformly mixing the remaining butyl acrylate, the remaining hydroxy acrylate monomer and the remaining initiator to obtain a second mixture; initiating polymerization by heating the first mixture to 80-85℃, and after the initiation is completed, the second mixture is added dropwise into the first mixture to perform a polymerization reaction (1-2h); and after the polymerization reaction is completed, the hydroxy acrylate oligomer is obtained by desolventizing under reduced pressure.

[0029] Optionally, the dropwise adding time is 1-2h.

[0030] The filler comprises filler with a particle size of 1-5μm and filler with a particle size of 20-50μm, and the weight ratio of the filler with a particle size of 1-5μm to the filler with a particle size of 20-50μm is 1:(0.8-1.5).

[0031] Optionally, the weight ratio of the filler with a particle size of 1-5μm to the filler with a particle size of 20-50μm is 1:(0.8-1.2).

[0032] Optionally, the filler comprises at least one of kaolin, barium sulfate, wollastonite, talcum powder and calcium carbonate.

[0033] The second aspect of the application provides a preparation method of a two-component polyurethane pouring sealant for filters, comprising the following steps: heating and vacuuming water from a plasticizer, adding polymeric MDI and stirring uniformly to obtain component A; mixing castor oil, polyether polyol, acrylate oligomer and filler, heating and vacuuming water, adding molecular sieve, color paste and auxiliary agent and stirring uniformly to obtain component B.

[0034] Advantages

[0035] 1. By limiting the weight ratio of castor oil, polyether polyol and acrylate oligomer to 1:(1-3):(4-10), the tensile strength of the prepared pouring sealant can be greater than 3MPa, the Shore A hardness can be greater than 85, the shear strength (ABS or aluminum) can be greater than 2MPa, and the Shore A hardness after aging at 143℃ can be greater than 50.

[0036] 2. By limiting the weight ratio of castor oil, polyether polyol and acrylate oligomer to 1:(1-2.5):(6-10),

[0037] The tensile strength of the prepared pouring sealant can be greater than 4MPa, and the shear strength (ABS or aluminum) can be greater than 3MPa.

[0038] 3. By limiting the weight ratio of castor oil, polyether polyol and acrylate oligomer to 1: (2-2.5): (8-10), the tensile strength of the prepared potting adhesive can be greater than 5 MPa, the Shore A hardness can be greater than 90, and the Shore A hardness after aging at 143℃ can be greater than 55.

[0039] 4. The prepared potting adhesive has excellent adhesion to plastics or metals, meeting the use requirements of filters.

[0040] 5. The preparation method of the potting adhesive is simple and easy to industrialize.

[0041] 6. The self-made acrylate oligomer avoids using strong-smelling mercaptan polymerization inhibitors, improving environmental friendliness. DETAILED DESCRIPTION

[0042] Examples 1-3, Comparative Examples 1-2

[0043] A two-component polyurethane potting adhesive for filters is composed of component A and component B. The component A is composed of 17 parts of polymeric MDI (isocyanate content of 30 wt%, purchased from Wanhua Chemical, model PM200) and 18 parts of plasticizer (epoxidized soybean oil, purchased from Tongxiang Chemical Co., Ltd.). The component B is composed of the following ingredients in parts by weight:

[0044] Table 1

[0045]

[0046] The castor oil is refined first-grade commercial castor oil without limiting the manufacturer; the polyether 310 and 303 are purchased from Lanting East; the filler is calcium carbonate (without limiting the manufacturer), with a particle size combination of 2 μm and 25 μm, and the weight ratio of 2 μm and 25 μm calcium carbonate is 1:1; the defoaming agent is purchased from BYK, with the model number BYK-2735; the molecular sieve is 5A low-alkali molecular sieve with a pH of 8-9, purchased from Luoyang Jianlong Micro-nano New Material Co., Ltd.; the catalyst is dibutyltin dilaurate.

[0047] The preparation raw materials of the acrylate oligomer are as follows in parts by weight: butyl acrylate 80 parts, hydroxyethyl acrylate 20 parts, initiator (BPO) 5 parts, and solvent (isopropyl alcohol) 150 parts.

[0048] The preparation method of the acrylate oligomer comprises the following steps: uniformly mixing 20% of butyl acrylate in total butyl acrylate, 20% of hydroxy acrylate monomer in total hydroxy acrylate, and 20% of initiator in total initiator with a solvent to obtain a first mixture; uniformly mixing the remaining butyl acrylate, the remaining hydroxy acrylate, and the remaining initiator to obtain a second mixture; initiating polymerization by heating the first mixture to 80-85°C, and lowering the internal temperature to 80±2°C after the initiation is completed; dropping the second mixture into the first mixture within 1.5h, and maintaining the reaction at 80±2°C for 1.5h after the dropping is completed, and then cooling to 40°C; and performing desolventization under reduced pressure at 50°C and -0.09MPa after the polymerization is completed, and recovering the solvent at -10°C to obtain a hydroxyl value of 97±2mgKOH / g of the hydroxy acrylate oligomer.

[0049] A preparation method of a two-component polyurethane pouring sealant for filters, wherein Examples 1-3 and Comparative Example 2, comprises the following steps: heating and vacuuming water from a plasticizer (110°C, -0.09MPa), adding polymeric MDI, and stirring uniformly to obtain component A; mixing castor oil, polyether polyol, acrylate oligomer, and filler, heating and vacuuming water, adding molecular sieve, color paste, and auxiliary agent, and stirring uniformly to obtain component B.

[0050] wherein Comparative Example 1, comprises the following steps: heating and vacuuming water from a plasticizer (110°C, -0.09MPa), adding polymeric MDI, and stirring uniformly to obtain component A; mixing castor oil, polyether polyol, and filler, heating and vacuuming water, cooling to 60°C, adding molecular sieve, color paste, and auxiliary agent, and stirring uniformly to obtain component B.

[0051] Performance test method

[0052] The pouring sealants prepared in the examples and comparative examples are tested according to the test standards (the weight ratio of components A and B is 35:100, and the room temperature curing time is 7 days at 25°C) to perform the following performance tests, and the test data are listed in Table 2.

[0053] 1. Tensile test:

[0054] Tested according to the national standard GB / T 1040.3-2006.

[0055] 2. Hardness test:

[0056] Tested according to the national standard GB / T531.1-2008.

[0057] 3. Shear test:

[0058] Tested according to the method of the national standard GB / T 2174-2008, and the substrates are ABS plates and aluminum plates.

[0059] 4. 143°C accelerated aging test

[0060] A, B components were mixed uniformly (A, B components weight ratio was 35:100), poured into a mold with thickness of 10 mm and diameter of 50 mm, cured at room temperature of 25°C for 7 days, then the sample was placed under saturated water vapor pressure of 143°C, taken out after 24 h, and the hardness was tested.

[0061] Performance test data

[0062] Table 2

[0063]

[0064] From the results in Table 2, compared with the preferred examples, the sealant of Comparative Example 1 without adding acrylate oligomer, and Comparative Example 2 with adjusted compounding ratio of castor oil, polyether polyol and acrylate oligomer, the tensile strength, shear strength and high temperature aging performance of the sealant all decreased obviously.

Claims

1. A two-component polyurethane potting compound for filters, characterized in that, It includes component A and component B. Component A includes polymeric MDI and plasticizer. Component B, by weight, includes: 3-5 parts castor oil, 5-20 parts polyether polyol, 10-30 parts acrylate oligomer, 40-60 parts filler, 5-10 parts molecular sieve, 1-5 parts color paste, and 0.01-0.5 parts additives.

2. The two-component polyurethane potting compound for filters according to claim 1, characterized in that, The weight ratio of castor oil, polyether polyol and acrylate oligomer is 1:(1-3):(4-10).

3. The two-component polyurethane potting compound for filters according to claim 1, characterized in that, The weight ratio of castor oil, polyether polyol and acrylate oligomer is 1:(1-2.5):(6-10).

4. The two-component polyurethane potting compound for filters according to claim 1, characterized in that, The isocyanate group content in the polymeric MDI is 28-35 wt%.

5. The two-component polyurethane potting compound for filters according to claim 4, characterized in that, The hydroxyl value of the acrylate oligomer is 90-160 mgKOH / g.

6. The two-component polyurethane potting compound for filters according to claim 6, characterized in that, The raw materials for preparing the acrylate oligomers include alkyl acrylate monomers and hydroxyalkyl acrylate monomers, wherein the hydroxyalkyl acrylate monomers include at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate.

7. The two-component polyurethane potting compound for filters according to claim 6, characterized in that, The method for preparing the acrylate oligomer includes the following steps: mixing 10-40% of the total alkyl acrylate monomers, 10-40% of the total hydroxyalkyl acrylate monomers, and 10-40% of the total initiator with a solvent to obtain a first mixture; mixing the remaining alkyl acrylate monomers, the remaining hydroxyalkyl acrylate monomers, and the remaining initiator to obtain a second mixture; heating the first mixture to initiate polymerization; after the initiation is complete, adding the second mixture dropwise to the first mixture to carry out the polymerization reaction; after the polymerization reaction is complete, removing the solvent under reduced pressure to obtain the hydroxyacrylate oligomer.

8. The two-component polyurethane potting compound for filters according to claim 7, characterized in that, The additives include at least one of catalysts, plasticizers, and defoamers.

9. The two-component polyurethane potting compound for filters according to claim 8, characterized in that, The filler includes fillers with a particle size of 1-5 μm and fillers with a particle size of 20-50 μm, and the weight ratio of the fillers with a particle size of 1-5 μm to the fillers with a particle size of 20-50 μm is 1:(0.8-1.5).

10. A method for preparing a two-component polyurethane potting compound for filters according to any one of claims 1-9, characterized in that, The process includes the following steps: heating and vacuum dehydrating the plasticizer, adding polymeric MDI, and stirring until homogeneous to obtain component A; mixing castor oil, polyether polyol, acrylate oligomer and filler, heating and vacuum dehydrating, adding molecular sieve, color paste and additives, and stirring until homogeneous to obtain component B.

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