Ultraviolet room-temperature dual-curing polyurethane pouring sealant and preparation method thereof

Abstract

The invention discloses an ultraviolet room-temperature dual-curing polyurethane pouring sealant which is a double-component pouring sealant and comprises a component A and a component B. The component A comprises a curing agent, a plasticizer I, a flame retardant and a photoinitiator. The component B comprises polyol, a plasticizer II, UV resin, a UV monomer and an auxiliary agent, and the photoinitiator contains hydroxyl. Ultraviolet and room temperature dual curing is adopted, the curing speed is increased, the bonding efficiency is improved, the hydroxyl-containing initiator, isocyanate and a reaction system act together, small molecules in a cured product are reduced, and the product performance is further improved.

Description

Technical Field

[0001] The invention relates to the field of adhesives, and in particular to an ultraviolet and room temperature dual-curing polyurethane potting adhesive and a preparation method thereof. Background Art

[0002] Polyurethane potting glue is a high-performance, multifunctional sealing material that can provide reliable sealing effects for electronic products, prevent moisture, dust, etc. from entering the interior of electronic devices, and improve the mechanical durability of devices. However, the traditional two-component polyurethane potting glue has a slow curing speed, which affects the production speed, and the potting glue produced needs to have appropriate hardness and toughness to ensure that the potting glue has good aging resistance. If the existing potting glue cures too fast, it is easy to cause the colloid to liquefy at high temperatures and lose the sealing effect. Therefore, it is very important to develop a polyurethane potting glue with a fast curing speed and excellent aging resistance.

[0003] Chinese invention patent CN110317564A discloses a polyurethane potting glue and its preparation method and application as well as a filling method for nylon components. Diisocyanate, vegetable oil polyol and chain extender are used in a molar ratio of 1: (5-10): (1-3) to obtain a hydroxyl-terminated addition reaction product, which has good bonding performance with nylon components, but the bonding curing speed is slow. Chinese invention patent CN106928895A discloses a polyurethane electronic potting glue for LED soft light strips and its preparation method. The two-component polyurethane electronic potting glue consists of component A and component B. Before use, the A:B weight ratio is 1-2:1 and the glue is evenly mixed and applied. It has good high and low temperature resistance, high strength and high elongation, and a large adjustable range of hardness, but poor aging resistance. Summary of the invention

[0004] In order to develop a polyurethane potting adhesive with fast curing speed and excellent aging resistance, the first aspect of the present invention provides a UV room temperature dual-curing polyurethane potting adhesive, the polyurethane potting adhesive is a two-component potting adhesive, including component A and component B, the component A includes a curing agent, a plasticizer I, a flame retardant, and a photoinitiator; the component B includes a polyol, a UV resin, a UV monomer, and an additive, the photoinitiator contains a hydroxyl group; the UV resin is a vinyl-containing UV resin.

[0005] As a preferred embodiment, the component B also includes a plasticizer II.

[0006] As a preferred embodiment, in parts by weight, the component A includes 40-50 parts of a curing agent, 30-40 parts of a plasticizer I, 10-20 parts of a flame retardant, and 1-5 parts of a photoinitiator; the component B includes 40-60 parts of a polyol, 10-25 parts of a plasticizer II, 10-30 parts of a UV resin, 5-20 parts of a UV monomer, and an auxiliary agent. The photoinitiator contains a hydroxyl group, and the UV resin is a vinyl-containing UV resin.

[0007] As a preferred embodiment, the photoinitiator is selected from at least one of initiator 184, initiator 1173, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and hydroxyethyl isobromobutyrate.

[0008] As a preferred embodiment, the curing agent is a diisocyanate, and the diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

[0009] As a preferred embodiment, the UV resin is a vinyl-containing polyurethane resin.

[0010] As a preferred embodiment, the UV monomer is a difunctional acrylate monomer.

[0011] As a preferred embodiment, the difunctional acrylate monomer is selected from at least one of dipropylene glycol diacrylate, hexanediol ethoxy diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and tricyclodecane dimethanol diacrylate.

[0012] During the experiment, the inventors found that the use of vinyl polyurethane resin, isocyanate, and hydroxyl-containing photoinitiators can achieve dual UV and moisture curing of polyurethane potting glue, improve the curing speed of polyurethane potting glue, and have good aging resistance. The possible reasons are speculated to be: the vinyl in the vinyl polyurethane resin reacts with isocyanate at a fast rate, and is matched with dipropylene glycol diacrylate to form a potting glue with a fast curing speed and appropriate hardness, which prevents excessive brittleness and fracture. The inventors further found that storing the photoinitiator and isocyanate separately after the reaction can improve storage stability and extend storage time. The reason may be: it can avoid the reaction of isocyanate and photoinitiator with vinyl polyurethane resin, so that the potting glue does not need to be stored away from light, but can achieve dual UV-moisture curing with a fast curing speed.

[0013] As a preferred embodiment, the plasticizer I and the plasticizer II are both selected from at least one of epoxy soybean oil, dioctyl adipate, and dioctyl terephthalate.

[0014] As a preferred embodiment, the polyol is selected from at least one of polyester polyol, polyether polyol and bio-based polyol.

[0015] As a preferred embodiment, the number average molecular weight of the polyether polyol is 5000-10000 Da, and the hydroxyl value is 25-35 mgKOH / g.

[0016] As a preferred embodiment, the auxiliary agent includes a defoaming agent or a catalyst, and the flame retardant is a phosphate catalyst.

[0017] As a preferred embodiment, in parts by weight, the defoamer is 0.01-0.1 parts, and the catalyst is 0.02-0.1 parts.

[0018] As a preferred embodiment, the flame retardant is selected from at least one of tricresyl phosphate, toluene diphenyl phosphate, tricresyl phosphate, triphenyl phosphate, triisopropylphenyl phosphate, tributyl phosphate, trioctyl phosphate, and tolyl diphenyl phosphate.

[0019] As a preferred embodiment, the defoaming agent is an organosilicon defoaming agent, and the catalyst is an organotin catalyst.

[0020] A second aspect of the present invention provides a method for preparing a UV-room temperature dual-curing polyurethane potting adhesive, comprising the following steps: S1 prepares component A: add plasticizer I, flame retardant, photoinitiator, stir evenly, heat to 80-100°C away from light, vacuum dehydrate, cool to 50-70°C, add curing agent, heat to 70-90°C, keep warm and away from light for 1-2h, cool to below 50°C, filter out the material, and store away from light; S2 prepares component B: mix and stir the UV resin and UV monomer evenly, heat and vacuum dehydrate; mix and stir the polyol and plasticizer II, heat to 100-120°C, vacuum dehydrate, cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly and add the additive to obtain component B.

[0021] As a preferred embodiment, the method for preparing the UV-room temperature dual-curing polyurethane potting adhesive comprises the following steps: S1: prepare component A: add plasticizer I, flame retardant, photoinitiator, stir evenly, heat to 80-100℃ away from light, vacuum dehydrate (water content below 200ppm), cool to 60℃, add curing agent, heat to 80℃, keep warm and away from light for 1-2h, cool to below 50℃, filter out the material, and store away from light; S2 prepares component B: mix and stir the UV resin and UV monomer evenly, heat to 80-100°C and dehydrate in vacuum (water content below 200ppm); mix and stir the polyol and plasticizer II, heat to 100-120°C, dehydrate in vacuum (water content below 200ppm), cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly and add additives to obtain component B.

[0022] As a preferred embodiment, the method for using the UV-room temperature dual-curing polyurethane potting adhesive is to mix component A and component B in a certain weight ratio and then use them.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The UV-room temperature dual-curing polyurethane potting adhesive of the present invention adopts UV and room temperature dual curing, which improves the curing speed, can achieve the potting adhesive not flowing within 1 minute, and improves the bonding efficiency.

[0024] (2) The UV-room temperature dual-curing polyurethane potting adhesive of the present invention stores the curing agent, initiator and reaction system separately, which reduces the requirements for storage conditions and improves storage stability.

[0025] (3) In the UV-room temperature dual-curing polyurethane potting adhesive of the present invention, the hydroxyl-containing initiator reacts with the isocyanate curing agent to improve the stability of component A, reduce the small molecules in the cured product, and further improve the product performance.

[0026] (4) The UV-room temperature dual-curing polyurethane potting glue of the present invention adopts a combination of castor oil and polyether polyol, so that the obtained potting glue has suitable hardness, tensile strength, elongation at break, and excellent mechanical properties.

[0027] (5) The UV-room temperature dual-curing polyurethane potting adhesive of the present invention has a fast light curing speed, good mechanical properties, and a long service life when used in the sealing of electronic devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is an accelerated aging test of the polyurethane potting glue prepared in Example 1 at 143°C, and from left to right are the initial state, 8h, 10h, 12h, and 14h later states.

[0029] Figure 2 The polyurethane potting glue prepared in Example 2 was subjected to an accelerated aging test at 143°C, with the states from left to right being the initial state, 8h, 10h, and 12h later.

[0030] Figure 3 The polyurethane potting glue prepared in Comparative Example 1 was subjected to an accelerated aging test at 143°C, with the initial state and the state after 8 hours from left to right.

[0031] Figure 4 The polyurethane potting glue prepared in Comparative Example 2 was subjected to an accelerated aging test at 143°C, with the states from left to right being the initial state, 8h, and 10h later.

[0032] Figure 5 The polyurethane potting glue prepared in Comparative Example 3 was subjected to an accelerated aging test at 143°C, with the initial state and the state after 8 hours from left to right. DETAILED DESCRIPTION

[0033] Example 1 A UV room temperature dual-curing polyurethane potting glue, wherein the polyurethane potting glue is a two-component potting glue, comprising a component A and a component B, which are specifically shown in Table 1 below in parts by weight.

[0034] Table 1

[0035] The liquefied MDI was purchased from Wanhua Chemical, with the brand name MDI-100LL; The epoxidized soybean oil was purchased from Tongxiang Chemical Co., Ltd. The TCP is tricresyl phosphate, purchased from Shandong Ruixing Flame Retardant Technology Co., Ltd. The castor oil was purchased from Sinochem Guangdong Co., Ltd. The polyether 303 was purchased from Bluestar Dongda Co., Ltd. with the brand name NJ-303; The vinyl-containing polyurethane resin was purchased from Zhongshan Jingwei New Materials Co., Ltd. with a brand name of 220-2C (viscosity 500±50 Pa·s, hydroxyl value 55±5 mg / g).

[0036] The preparation methods of Example 1 and Example 2 are the same as follows: A method for preparing a UV-room temperature dual-curing polyurethane potting adhesive comprises the following steps: S1: Prepare component A: Add plasticizer I, flame retardant, photoinitiator, stir evenly, heat to 90°C in dark, dehydrate under vacuum (water content below 200 ppm), cool to 60°C, add curing agent, heat to 80°C, keep warm and react in dark for 2 hours, cool to below 50°C, filter out the material, and store in dark; S2 prepares component B: mix and stir the UV resin and UV monomer evenly, heat to 90°C for vacuum dehydration (water content below 200 ppm); mix and stir the polyol and plasticizer II, heat to 110°C, vacuum dehydrate (water content below 200 ppm), cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly, and add additives to obtain component B.

[0037] Comparative Example 1 A method for preparing a UV-room temperature dual-curing polyurethane potting adhesive comprises the following steps: S1 Add plasticizer I and flame retardant, stir evenly, heat to 90°C away from light, vacuum dehydrate (water content below 200ppm), cool to 50°C, add curing agent, stir evenly, and filter out the material; S2: Mix and stir the polyol and plasticizer II, heat to 110°C, vacuum dehydrate (water content below 200ppm), cool to below 40°C, add the auxiliary agent and stir evenly to obtain the product.

[0038] Comparative Example 2 A method for preparing a UV-room temperature dual-curing polyurethane potting adhesive comprises the following steps: S1 Add plasticizer I, flame retardant, photoinitiator, stir evenly, heat to 90°C away from light, vacuum dehydrate (water content below 200ppm), cool to 50°C, add isocyanate curing agent, stir evenly, filter out the material, and store away from light; S2: Mix and stir the UV resin and UV monomer evenly, heat to 90°C for vacuum dehydration (water content below 200ppm); mix and stir the polyol and plasticizer II, heat to 110°C, vacuum dehydrate (water content below 200ppm), cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly and add the additive to obtain.

[0039] Comparative Example 3 A method for preparing a UV-room temperature dual-curing polyurethane potting adhesive comprises the following steps: S1 Add plasticizer I and flame retardant, stir evenly, heat to 90°C away from light, vacuum dehydrate (water content below 200ppm), cool to 50°C, add curing agent, stir evenly, and filter out the material; S2: Mix and stir the UV resin and UV monomer evenly, heat to 90°C for vacuum dehydration (water content below 200ppm); mix and stir the polyol and plasticizer II, heat to 110°C, vacuum dehydrate (water content below 200ppm), cool to below 80°C, add the photoinitiator, and stir evenly; cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly, and then add the auxiliary agent to obtain.

[0040] Performance Testing 1. Light curing effect test Weigh the prepared component A and component B in a weight ratio of 100:100, stir evenly, pour the glue with a thickness of 2-3mm into the mold, quickly place the mold in a UV light curing machine, and cure it for 1 minute with UV light energy (130mw / cm 2 ), take it out and observe the curing effect.

[0041] 2. Aging performance test: Weigh the prepared component A and component B in a weight ratio of 100:100, stir evenly, pour 30g of the sample into the mold, quickly place the mold in a UV light curing machine, and cure it for 1min with UV light energy (130mw / cm 2 ), left to stand at room temperature for 7 days, and after complete curing, the sample was placed in an accelerated aging tester at 143°C and 0.3MPa high pressure for testing.

[0042] For pictures of performance test results, see Figure 1-5 ; From left to right are the initial, 8h, 10h, 12h, 14h after the state, see Example 1 Figure 1 ; Example 2 see Figure 2 ; Example 3 see Figure 3 ; Example 4 see Figure 4 ; Example 5 see Figure 5 .

[0043] 3.Tensile strength and elongation at break test: Tested according to GB / T 528-2009.

[0044] 4. Storage stability test: Weigh 200 g of component A and group B respectively, put them into a 250 mL covered container, place them at room temperature in a light-proof environment, let them stand for 7 days, and observe the appearance.

[0045] 5. Hardness test: Weigh the prepared component A and component B in a weight ratio of 100:100, stir evenly, pour 30g of the sample into the mold, quickly place the mold in a UV light curing machine, and cure it for 1min with UV light energy (130mw / cm 2 ), and the Shore hardness was tested after being placed at room temperature (25°C) for 7 days.

[0046] The performance test results are shown in Table 2.

[0047] Table 2 .

Claims

1. A UV room temperature dual-curing polyurethane potting adhesive, characterized in that: The polyurethane potting glue is a two-component potting glue, including component A and component B, wherein the component A includes a curing agent, a plasticizer I, a flame retardant, and a photoinitiator; the component B includes a polyol, a UV resin, a UV monomer, and an additive, and the photoinitiator contains a hydroxyl group; The UV resin is a vinyl-containing UV resin.

2. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 1, characterized in that: The photoinitiator is selected from at least one of initiator 184, initiator 1173, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, and hydroxyethyl isobromobutyrate.

3. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 1, characterized in that: The curing agent is a diisocyanate, and the diisocyanate is selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate.

4. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 1, characterized in that: The UV resin is a vinyl-containing polyurethane resin.

5. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 1, characterized in that: The UV monomer is a difunctional acrylate monomer.

6. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 5, characterized in that: The difunctional acrylate monomer is selected from at least one of dipropylene glycol diacrylate, hexanediol ethoxy diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and tricyclodecane dimethanol diacrylate.

7. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 5, characterized in that: The polyol is selected from at least one of polyester polyol, polyether polyol and bio-based polyol.

8. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 7, characterized in that: The number average molecular weight of the polyether polyol is 5000-10000 Da, and the hydroxyl value is 25-35 mgKOH / g.

9. The UV-room temperature dual-curing polyurethane potting adhesive according to claim 1, characterized in that: The auxiliary agent includes a defoamer or a catalyst, and the flame retardant is a phosphate catalyst.

10. A method for preparing the UV-room temperature dual-curing polyurethane potting adhesive according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1 prepares component A: add plasticizer I, flame retardant, photoinitiator, stir evenly, heat to 80-100°C away from light, vacuum dehydrate, cool to 50-70°C, add curing agent, heat to 70-90°C, keep warm and away from light for 1-2h, cool to below 50°C, filter out the material, and store away from light; S2 prepares component B: mix and stir the UV resin and UV monomer evenly, heat and vacuum dehydrate; mix and stir the polyol and plasticizer II, heat to 100-120°C, vacuum dehydrate, cool to below 40°C, mix the dehydrated UV resin and UV monomer with the polyol and plasticizer II, stir evenly and add the additive to obtain component B.

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