Low-density low-viscosity polyurethane pouring sealant containing plastic microspheres and preparation method thereof

Abstract

The invention discloses a low-density low-viscosity polyurethane pouring sealant containing plastic microspheres and a preparation method thereof. The pouring sealant comprises a component A and a component B, the component A comprises the following components in parts by weight: 25-40 parts of castor oil polyol and 9-24 parts of modified castor oil polyol containing a benzene ring structure; 15 to 22 parts of polyester polyol; 10 to 17 parts of plastic microspheres; 12-16 parts of a liquid flame retardant; 0.2 to 0.3 part of an amine catalyst; 0.3 to 0.4 part of a metal catalyst; 0.1 to 0.4 part of a coupling agent; 0.1 to 0.4 part of a defoaming agent; 2-6 parts of a dewatering agent; wherein the ester polyol is Zibo charge beauty CM-1830 polyester polyol. The two-component polyurethane pouring sealant with low viscosity, low density and better mechanical property is prepared by selecting the polyester polyol in the component A and selecting and proportioning other components.

Description

Technical Field

[0001] The invention relates to the technical field of two-component polyurethane adhesive, and in particular to a low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres and a preparation method thereof. Background Art

[0002] Potting glue is a key material used to protect electronic components. It can strengthen the overall structure of the device, improve its impact and vibration resistance, improve internal insulation, promote the miniaturization and lightweight of the device, and effectively prevent direct exposure of components and circuits, and improve waterproof and moisture-proof performance. In the electronics industry, potting glue plays an important role and is an indispensable material in the manufacture of electronic devices.

[0003] Polyurethane potting glue can maintain the stability of its performance in a wide temperature range. In addition, it has the advantages of excellent adhesion, flexibility, vibration resistance, long life, simple construction and low cost, which makes it widely used in electronics, aviation, automobile and other fields.

[0004] Polyurethane potting glue is widely used in the electronic sealing process of new energy vehicle power battery packs and electronic components, and currently lightweighting has become an important direction in the development of new energy vehicles and electronic components. Therefore, the selection of low-density, low-viscosity and highly flame-retardant potting glue in the battery pack sealing process has become the first choice for polyurethane potting glue. Plastic microspheres are expandable microspheres, which can effectively reduce the density when added to potting glue. However, on the one hand, since the surface of plastic microspheres does not contain functional groups that can react with the matrix, its microscopic surface bonding force is relatively poor. On the other hand, due to the low density of plastic microspheres, when they are used in potting glue, stratification will occur, resulting in relatively poor performance of the prepared potting glue, such as low strength, limited elongation at break, and high viscosity. In some areas that require high strength and simple construction, it is difficult to meet the requirements. Summary of the invention

[0005] Purpose of the invention: The first purpose of the present invention is to provide a low-density, low-viscosity polyurethane potting glue containing plastic microspheres, which has good strength, elongation at break, and stability while maintaining low density, low viscosity and high flame retardancy; the second purpose of the present invention is to provide a method for preparing the low-density, low-viscosity polyurethane potting glue containing plastic microspheres.

[0006] The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres of the present invention comprises component A and component B;

[0007] Component A includes, by weight: 25-40 parts of castor oil polyol, 9-24 parts of modified castor oil polyol containing benzene ring structure; 15-22 parts of polyester polyol; 10-17 parts of plastic microspheres; 12-16 parts of liquid flame retardant; 0.2-0.3 parts of amine catalyst; 0.3-0.4 parts of metal catalyst; 0.1-0.4 parts of coupling agent; 0.1-0.4 parts of defoaming agent; 2-6 parts of dewatering agent; wherein the polyester polyol is CM-1830 polyester polyol (purchased from Zibo Chongmei);

[0008] Calculated by weight, component B includes: 5 to 70 parts of low-functionality polyisocyanate A; 30 to 85 parts of multifunctionality polyisocyanate B; and 10 to 25 parts of liquid flame retardant.

[0009] Component A and component B are mixed according to the isocyanate index. Preferably, the mass ratio of component A to component B is 3:1.

[0010] In the present invention, by allocating the specific components and dosage of the polyester polyol in component A, a two-component polyurethane potting material that maintains low density characteristics and exhibits excellent mechanical properties and flame retardant properties is obtained. The selected Zibo Chongmei CM-1830 polyester polyol is a phthalic anhydride polyester with a unique phosphorus-containing flame retardant structure, which exhibits excellent heat resistance. The hydroxyl content in its molecule is relatively high, giving it more outstanding reactivity. While fully meeting the flame retardant performance requirements, it also cleverly balances the mechanical properties of the material, achieving dual optimization of performance and safety. By controlling the amount of polyester polyol in component A, a two-component polyurethane potting glue with excellent performance is prepared. If the amount of polyester polyol is too little, the strength of the prepared two-component polyurethane potting glue is poor; if the amount of polyester polyol is too much, the prepared two-component polyurethane potting glue has poor elongation at break. This material is designed to meet the high standards of power battery packs and electronic components for lightweight, convenient sealing operation and excellent flame retardant properties.

[0011] The present invention cleverly uses low-density fillers and precisely controls the amount of fillers added within an optimal range, thereby achieving a two-component potting compound with excellent mechanical properties and low density. If the amount of low-density fillers exceeds the limit, the mechanical properties of the potting compound will be impaired; conversely, if the amount is insufficient, it will be difficult to meet the lightweight requirements. Through careful balance, a perfect balance between performance and density is achieved.

[0012] In the present invention, the best operation time of the potting compound can be controlled by using a catalyst. Too much catalyst will lead to too fast curing time and inconvenience in construction, while too little catalyst will cause stratification of low-density fillers during potting compound curing.

[0013] Preferably, the modified castor oil polyol containing a benzene ring structure is AP11-1 (purchased from Shanghai Jingri New Materials) or URIC AC009 (purchased from Ito Oil). The benzene ring structure is very stable, and its introduction helps to improve the chemical stability of the modified castor oil, making its product perform better in high temperature and oxidative environments.

[0014] Preferably, the castor oil polyol has a molecular weight of 1000-1100 and a hydroxyl value of 163-167.

[0015] Preferably, the plastic microspheres are at least one of Expancel 092DU80 (purchased from Nouryon), 3MK1 (purchased from 3M Company) or 3MS38HS (purchased from 3M Company).

[0016] Preferably, the liquid flame retardant is at least one of triethyl phosphate, dimethyl methyl phosphate or trichloroethyl phosphate.

[0017] Preferably, the amine catalyst is at least one of triethylenediamine, triethylenediamine or dimethylcyclohexylamine.

[0018] Preferably, the metal catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate or stannous octoate.

[0019] Preferably, the coupling agent is selected from Dow Corning Z-6011 coupling agent.

[0020] Preferably, the defoamer is selected from BYK-054 defoamer.

[0021] Preferably, the dehydrating agent is a molecular sieve, and further preferably, it is selected from Xianfeng Nanomaterials KIT6 molecular sieve.

[0022] Preferably, the functionality of the low-functionality polyisocyanate A is 2, and the functionality of the multifunctional polyisocyanate B is 2.5-2.7.

[0023] The low-functionality polyisocyanate A is selected from Wanhua's MDI-LL polyisocyanate, and has a functionality of 2.

[0024] The high-functionality polyisocyanate B is selected from Wanhua's M20S polyisocyanate, and has an average functionality of 2.5 to 2.7.

[0025] By combining low-functionality polyisocyanate A and high-functionality polyisocyanate B, the strength and toughness of the product can be balanced.

[0026] The method for preparing the low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres of the present invention comprises the following steps:

[0027] (1) Castor oil polyol, modified castor oil polyol containing a benzene ring structure, polyester polyol CM-1830, and liquid flame retardant are dehydrated and mixed, and then a coupling agent, a defoaming agent, a water absorbent, a low-density filler, and a catalyst are added to mix to obtain component A;

[0028] (2) mixing polyisocyanate A, polyisocyanate B and a liquid flame retardant to obtain component B;

[0029] (3) Component A and component B are mixed evenly to obtain the low-viscosity and low-density two-component polyurethane potting adhesive containing plastic microspheres.

[0030] Preferably, the dehydration conditions are: heating to 110° C. to 120° C., vacuuming to less than -0.090 MPa, and dehydration time of 1.5 to 3 hours.

[0031] Preferably, in steps (1), (2) and (3), the mixing method is to evacuate the mixture to a pressure below -95 kPa and perform high-speed mixing for 2 to 3 minutes.

[0032] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) By designing the specific composition of component A, and further using low-density fillers, catalysts, and polyester polyols, and controlling their amounts within a specific range, a two-component polyurethane potting adhesive with low viscosity, low density, and good mechanical properties is prepared, and its density is 0.54-0.8 g / cm 3 , Shore A hardness is 52-75, tensile strength is 2-5.5 MPa, and elongation at break is 102-174%; (2) The preparation method is simple and easy to industrialize. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres of the present invention comprises the following steps:

[0036] (1) By weight, 34 parts of castor oil polyol Sovermol-750 (purchased from BASF, molecular weight 1020, hydroxyl value 165), 15 parts of modified castor oil polyol AP11-1 containing a benzene ring structure (purchased from Shanghai Jingri New Materials), 15 parts of polyester polyol CM-1830 (purchased from Zibo Chongmei, molecular weight 700, hydroxyl value 210), and 15 parts of liquid flame retardant triethyl phosphate (purchased from Zhongjie Chemical) were heated to 110°C to 120°C, vacuumed to less than -0.090 MPa, and dehydrated for 2 hours, and then mixed with 0.4 parts of coupling agent Z-6011 (purchased from Dow Corning), 0.1 parts of defoaming agent BYK-054 (purchased from Bick), 3 parts of dehydrating agent molecular sieve KIT6 (purchased from Xianfeng Nanomaterials), and 17 parts of plastic microspheres Expancel 092DU80 (purchased from Nouryon), 0.2 parts of amine catalyst triethylenediamine, 0.4 parts of metal catalyst dibutyltin dilaurate, evacuate to a pressure below -95 kPa, and mix at high speed for 3 minutes to obtain component A;

[0037] (2) 15 parts of low-functionality polyisocyanate AMDI-LL (functionality 2, purchased from Wanhua), 70 parts of multifunctional polyisocyanate B M20S (average functionality 2.5-2.7, purchased from Wanhua), and 15 parts of liquid flame retardant triethyl phosphate (purchased from Zhongjie Chemical) were evacuated to a pressure below -95 kPa and mixed at high speed for 5 minutes to obtain component B;

[0038] (3) Component A and component B are mixed uniformly at a mass ratio of 3:1 to obtain the low-viscosity and low-density two-component polyurethane potting adhesive containing plastic microspheres.

[0039] The specific compositions and amounts (by weight) of Examples 1 to 8 and Comparative Examples 1 to 6 are shown in Tables 1 and 2 below, and the other conditions are the same as those of Example 1.

[0040] The performance of the samples of Examples 1 to 8 and Comparative Examples 1 to 6 was tested. The specific test method is as follows. The test results are detailed in Tables 1 and 2:

[0041] Density: Tested according to GB / T 533-2008;

[0042] Hardness: Tested according to GB / T-531.2 2009;

[0043] Tensile strength: tested according to GB / T 528-2009;

[0044] Elongation at break: tested according to GB / T 528-2009;

[0045] Operation time: Tested according to GB / T 2794-2013, the time when the viscosity after mixing is <5000cps;

[0046] Viscosity: Tested according to GB / T 2794-2013;

[0047] Initial curing time: For adhesive thickness greater than 5mm, do not turn over within 80 minutes;

[0048] Flame retardant performance: UL94 standard;

[0049] Stability: The 20 mm thick slices prepared in the examples and comparative examples were placed at room temperature for 24 h to observe whether stratification occurred; if no stratification occurred, it was recorded as "uniform", and if stratification occurred, it was recorded as "stratified".

[0050] Table 1 Raw material ratios and performance parameters of Examples 1 to 8

[0051]

[0052]

[0053] Table 2 Comparative Examples 1 to 6 Raw Material Ratios and Performance Parameters

[0054]

[0055]

[0056] As shown in Table 1, in Examples 1 to 8, by designing the specific composition of component A, and further using plastic microspheres, catalysts, and polyester polyols, and controlling their amounts within a specific range, a two-component polyurethane potting adhesive with low viscosity, low density, and good mechanical properties was prepared, and its density was 0.54-0.8 g / cm 3 , Shore A hardness is 52-75, tensile strength is 2-5.5 MPa, elongation at break is 102-174%, and flame retardant grade is V0. The two-component polyurethane potting adhesive provided by the present invention can be designed to meet the high standard requirements of power battery packs and electronic components for lightweight and convenient packaging operations.

[0057] Compared with Example 5, if the amount of catalyst in component A of the potting glue is too little (Comparative Example 1), the curing speed of the prepared potting glue is too slow, and the potting glue is stratified, resulting in poor mechanical properties; if the amount of catalyst in component A is too much (Comparative Example 2), the operation time of the prepared potting glue is too fast, which does not meet the requirements of convenient operation.

[0058] Compared with Example 1, if there are too many plastic microspheres in component A (Comparative Example 3), the mechanical properties of the prepared potting glue deteriorate, the mixing viscosity increases, and the requirement of convenient operation is not met; compared with Example 8, if there are too few plastic microspheres in component A (Comparative Example 4), the density of the prepared potting glue is too large and the requirement of lightweight is not met.

[0059] Compared with Example 1, if the amount of polyester polyol in component A is too small (Comparative Example 5), the mechanical properties of the potting compound will deteriorate; compared with Example 8, if the amount of polyester polyol in component A is too large (Comparative Example 6), the tensile strength will deteriorate, and the comprehensive performance of the final two-component potting compound prepared will be poor.

[0060] Compared with Example 5, when other types of polyester polyols (such as polycaprolactone polyols) are selected to replace CM-1850 polyester polyol to synthesize the polyurethane adhesive (refer to Comparative Example 7), the prepared adhesive exhibits lower tensile strength, the mechanical properties are significantly weakened, and its flame retardant properties are significantly reduced, which cannot meet the material standards for high flame retardancy and high mechanical properties.

Claims

1. A low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres, characterized in that: The potting compound comprises component A and component B; Component A includes, by weight: 25-40 parts of castor oil polyol, 9-24 parts of modified castor oil polyol containing benzene ring structure; 15-22 parts of polyester polyol; 10-17 parts of plastic microspheres; 12-16 parts of liquid flame retardant; 0.2-0.3 parts of amine catalyst; 0.3-0.4 parts of metal catalyst; 0.1-0.4 parts of coupling agent; 0.1-0.4 parts of defoaming agent; 2-6 parts of dewatering agent; wherein the polyester polyol is CM-1830 polyester polyol; Calculated by weight, component B includes: 5 to 70 parts of low-functionality polyisocyanate A; 30 to 85 parts of multifunctionality polyisocyanate B; and 10 to 25 parts of liquid flame retardant.

2. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The modified castor oil polyol containing a benzene ring structure is AP11-1 or URIC AC009.

3. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The amine catalyst is at least one of triethylenediamine, triethylenediamine or dimethylcyclohexylamine.

4. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The metal catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate or stannous octoate.

5. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The plastic microspheres are at least one of Expancel 092DU80, 3MK1 or 3MS38HS.

6. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The liquid flame retardant is at least one of triethyl phosphate, dimethyl methyl phosphate or trichloroethyl phosphate.

7. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The functionality of the low-functionality polyisocyanate A is 2, and the functionality of the multifunctional polyisocyanate B is 2.5-2.

7.

8. The low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 1, characterized in that: The castor oil polyol has a molecular weight of 1000-1100 and a hydroxyl value of 163-167.

9. A method for preparing the low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) dehydrating castor oil polyol, modified castor oil polyol containing a benzene ring structure, polyester polyol, and liquid flame retardant, respectively, and then mixing them with a coupling agent, a defoaming agent, a water absorbent, a low-density filler, and a catalyst to obtain component A; (2) mixing polyisocyanate A, polyisocyanate B and a liquid flame retardant to obtain component B; (3) Component A and component B are mixed evenly to obtain the low-viscosity and low-density two-component polyurethane potting adhesive containing plastic microspheres.

10. The method for preparing the low-density and low-viscosity polyurethane potting adhesive containing plastic microspheres according to claim 3, characterized in that: The dehydration conditions are: heating to 110° C. to 120° C., vacuuming to less than -0.090 MPa, and dehydration time of 1.5 to 3 hours.

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