A waterproof and sealed chip hot melt adhesive and its preparation method

Abstract

The present invention relates to a waterproof and sealed chip hot melt adhesive and a preparation method thereof, and relates to the field of hot melt adhesives. A waterproof and sealed chip hot melt adhesive comprises the following raw materials in parts by weight: 20-35 parts of crystalline polyol; 30-45 parts of non-crystalline polyol containing a benzene ring structure; 2-7 parts of castor oil; 10-18 parts of aromatic diisocyanate; 2-4 parts of 3-isocyanatopropyltriethoxysilane; 0.2-0.5 part of catalyst; 4-9 parts of terpene phenolic resin; 1-2 parts of antioxidant. This application can improve the high temperature resistance and waterproofness of the hot melt adhesive, and ensure the sealing performance and reliability of the encapsulation structure in high temperature or humid environments.

Description

Technical Field

[0001] The present invention relates to the field of hot melt adhesives, and particularly to a waterproof and sealed chip hot melt adhesive and a preparation method thereof. Background Art

[0002] Hot melt adhesive is a plastic adhesive, whose physical form changes with temperature within a certain temperature range, but its chemical properties remain unchanged. Under the awareness of environmental protection, solvent-free hot melt adhesives are favored because there are no organic volatile substances during the use process. The solvent-free hot melt adhesive can be melted into a viscous liquid when heated to a certain temperature. After wetting the adherend, it can bond the adherend when cooled to room temperature.

[0003] Hot melt adhesives can be divided into several categories such as ethylene-vinyl acetate, polyester, polyamide, and polyurethane. Among them, polyurethane hot melt adhesives have good toughness, excellent low-temperature resistance, convenient sizing, strong adhesive force, and a wide range of adhesive substrates, and are widely used in fields such as construction, light textile, electronic appliances, machinery manufacturing, aerospace, etc. In the field of electronic appliances, polyurethane hot melt adhesives can be used for the encapsulation and protection of chips, bonding and fixing the chips on the substrate to achieve a sealing and protective effect.

[0004] When the existing polyurethane hot melt adhesives are used to bond chips, their high-temperature resistance and waterproof effect are not good. The chips may generate high temperatures or be exposed to humid and rainy environments during use. Moisture entering the chips may cause short circuits, component corrosion, etc., affecting the sealing and reliability of the encapsulation structure in high-temperature or humid environments. Summary of the Invention

[0005] In order to improve the high-temperature resistance and waterproofness of the hot melt adhesive and ensure the sealing and reliability of the encapsulation structure in high-temperature or humid environments, the present application provides a waterproof and sealed chip hot melt adhesive and a preparation method thereof.

[0006] A waterproof and sealed chip hot melt adhesive and a preparation method thereof provided by the present application adopt the following technical solutions:

[0007] A waterproof and sealed chip hot melt adhesive, comprising the following raw materials in parts by weight:

[0008] 20-35 parts of crystalline polyol;

[0009] 30-45 parts of non-crystalline polyol containing a benzene ring structure;

[0010] 2-7 parts of castor oil;

[0011] 10-18 parts of aromatic diisocyanate;

[0012] 2-4 parts of 3-isocyanatopropyltriethoxysilane;

[0013] 0.2-0.5 part of catalyst;

[0014] 4 - 9 parts of terpene phenolic resin;

[0015] 1 - 2 parts of antioxidant.

[0016] Adopting the above technical solution, this application combines a crystalline polyol, a non - crystalline polyol with a benzene - ring structure, and castor oil. The crystalline polyol is beneficial to improving the initial adhesion strength of the hot - melt adhesive, while the non - crystalline polyol with a benzene - ring structure is beneficial to improving the flexibility and open time of the hot - melt adhesive. The introduction of the benzene - ring structure and the benzene - ring in the aromatic diisocyanate enhances the heat resistance. Castor oil replaces part of the petroleum - based polyol, which is also beneficial to improving the waterproof performance of the hot - melt adhesive. Through an appropriate ratio, the polyurethane hot - melt adhesive has excellent initial adhesion strength and final adhesion strength, and at the same time has excellent flexibility, high - temperature resistance and waterproof performance.

[0017] By selecting 3 - isocyanatopropyltriethoxysilane to block and modify the hot - melt adhesive, a Si - O - Si network structure is formed during the cross - linking and curing process, which is beneficial to improving the water resistance and heat resistance of the hot - melt adhesive. At the same time, the contained isocyanate group participates in the curing, improving the bonding strength; selecting terpene phenolic resin as the tackifying resin, the system has good compatibility, and can modify the initial tackiness and temperature resistance of the hot - melt adhesive. The polyurethane hot - melt adhesive prepared in this application has excellent high - temperature resistance and waterproofness, and is suitable for the encapsulation and sealing protection of chips.

[0018] Further, the castor oil is selected as modified castor oil, and the modified castor oil is prepared from the following raw materials in parts by weight:

[0019] 50 - 60 parts of castor oil;

[0020] 7 - 12 parts of mercaptoethanol;

[0021] 4 - 6 parts of azobisisobutyronitrile;

[0022] 9 - 12 parts of glycerol;

[0023] 0.05 - 0.1 part of sodium hydroxide.

[0024] Adopting the above technical solution, mercaptoethanol and glycerol are used to modify castor oil, introducing hydroxyl functional groups, which is beneficial to improving the reaction with aromatic diisocyanate, increasing the cross - link density, and thus improving the bonding strength. At the same time, the modified castor oil reduces the reaction with water molecules and is more adaptable to the humid and high - heat environment.

[0025] Further, the crystalline polyol is selected from one or more of poly(1,6 - hexanediol adipate) diol, poly(1,4 - butanediol adipate) diol, poly(ethylene glycol adipate) diol, and poly(2,3 - dimethyl - 2,3 - butanediol).

[0026] Further, the non-crystalline polyol containing a benzene ring structure is selected from one or more of a polyester polyol of phthalic acid / neopentyl glycol, a polyester polyol of adipic acid / isophthalic acid / hexanediol, a polyester polyol of isophthalic acid / hexanediol / neopentyl glycol, and a polyester polyol of adipic acid / terephthalic acid / phthalic acid / ethylene glycol.

[0027] By adopting the above technical solution, a polybasic acid containing a benzene ring structure is selected to react with a diol, and a benzene ring is introduced into the polyester polyol to improve heat resistance and corrosion resistance.

[0028] Further, the non-crystalline polyol containing a benzene ring structure is made from the following raw materials: adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid, and triphenyl phosphite, wherein the molar ratio of adipic acid, terephthalic acid, trimellitic anhydride, and neopentyl glycol is 3 - 3.5:1:0.8 - 1:6 - 9, and the masses of p-toluenesulfonic acid and triphenyl phosphite are 300 - 600 ppm and 100 - 200 ppm of the total mass of the acids, respectively.

[0029] By adopting the above technical solution, p-toluenesulfonic acid is selected as the catalyst and triphenyl phosphite as the stabilizer. In the aliphatic polyester polyol prepared from adipic acid and neopentyl glycol, terephthalic acid and trimellitic anhydride are introduced, making the chain segments relatively random and the crystallinity low, so that the polyurethane hot melt adhesive has a long open time and high bonding strength.

[0030] Further, the aromatic diisocyanate is selected from one or more of diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, toluene diisocyanate, and diphenylmethylene diisocyanate.

[0031] By adopting the above technical solution, the benzene ring in the diisocyanate improves the heat resistance.

[0032] Further, the catalyst is selected from one or more of dibutyltin dilaurate, triethylenediamine, and dimorpholinodiethyl ether.

[0033] This application also provides a preparation method for a waterproof and sealed chip hot melt adhesive, which includes the following steps:

[0034] Put the crystalline polyol, the non-crystalline polyol containing a benzene ring structure, castor oil, and terpene phenolic resin into a reaction kettle, heat to 100 - 130 °C, and carry out vacuum dehydration for 2 - 3 h under stirring, with the vacuum degree being -0.01 - 0.05 MPa;

[0035] Cool down to 70 - 75 °C, add the catalyst and aromatic isocyanate to the reaction kettle, protect with nitrogen, and raise the temperature to react at 80 - 90 °C for 2 - 3 h;

[0036] Put 3-isocyanatopropyltrimethoxysilane and antioxidant into the reaction kettle, stir and mix at 115-125°C for 0.5-1 h under nitrogen protection, conduct vacuum degassing for 1-1.5 h, discharge the material, and seal and package it under nitrogen protection.

[0037] Adopting the above technical solution, the preparation method is simple and environmentally friendly, without volatile organic compounds, and a moisture-curing polyurethane hot melt adhesive with high bonding strength, high temperature resistance and waterproof performance is obtained.

[0038] Furthermore, when the castor oil is selected as modified castor oil, it is prepared through the following steps:

[0039] Put the castor oil and mercaptoethanol into the reaction kettle, pass nitrogen for protection and heat to 75-80°C, add azobisisobutyronitrile and react for 3-4 h, raise the temperature to 100-105°C and continue to react for 2-2.5 h, cool down and add ethyl acetate, wash with brine and water, conduct drying treatment with anhydrous magnesium sulfate, and evaporate to remove ethyl acetate to obtain an intermediate;

[0040] Put the intermediate and glycerol into the mixing kettle, add sodium hydroxide under stirring, raise the temperature to 170-180°C, and react for 1-2 h under nitrogen protection to obtain modified castor oil.

[0041] Adopting the above technical solution, the preparation method is simple and the yield is high, and a modified castor oil with moisture and heat resistance is obtained.

[0042] Furthermore, the non-crystalline polyol containing a benzene ring structure is prepared through the following steps:

[0043] Put adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid and triphenyl phosphite into the polymerization kettle, pass nitrogen for protection and raise the temperature to 170-200°C. After keeping warm and dehydrating 60%-70%, continue to raise the temperature in units of 10°C. When the temperature rises to 220-230°C, start to keep warm and measure the acid value. When the acid value of the material is lower than 15 mgKOH / g, start to pump vacuum, keep the temperature at 220°C-230°C. When the acid value ≤ 2 mgKOH / g and the hydroxyl value is 30-100 mgKOH / g, stop the reaction, cool down and discharge the material to obtain a non-crystalline polyol containing a benzene ring structure.

[0044] Adopting the above technical solution, improving the preparation process makes the preparation process more stable and controllable, and a non-crystalline polyol containing a benzene ring structure with controllable hydroxyl value and acid ester is obtained.

[0045] In summary, the present application has the following beneficial effects:

[0046] 1. In this application, a crystalline polyol is combined with a non-crystalline polyol containing a benzene ring structure and castor oil. The crystalline polyol is beneficial to improving the initial adhesion strength of the hot melt adhesive, while the non-crystalline polyol containing a benzene ring structure is beneficial to improving the flexibility and open time of the hot melt adhesive. The introduction of the benzene ring structure and the benzene ring in the aromatic diisocyanate enhances the heat resistance. Castor oil replaces part of the petroleum-based polyol, which is also beneficial to improving the waterproof performance of the hot melt adhesive. Through an appropriate ratio, the polyurethane hot melt adhesive has excellent initial adhesion strength and final adhesion strength, and at the same time has excellent flexibility, high temperature resistance and waterproof performance.

[0047] By using 3-isocyanatopropyltriethoxysilane to block and modify the hot melt adhesive, a Si-O-Si network structure is formed during the cross-linking and curing process, which is beneficial to improving the water resistance and heat resistance of the hot melt adhesive. At the same time, the isocyanate group contained participates in the curing, improving the bonding strength; using terpene phenolic resin as the tackifying resin, the system has good compatibility and can modify the initial tackiness and temperature resistance of the hot melt adhesive. The polyurethane hot melt adhesive prepared in this application has excellent high temperature resistance and waterproof performance and is suitable for the encapsulation and sealing protection of chips.

[0048] 2. Mercaptoethanol and glycerol are used to modify castor oil, introducing hydroxyl functional groups, which is beneficial to improving the reaction with aromatic diisocyanates, increasing the cross-linking density, thereby improving the bonding strength. At the same time, the modified castor oil reduces the reaction with water molecules and is more adaptable in a humid and high-temperature environment. Detailed implementation mode

[0049] The following is a further detailed description of this application in combination with...

[0050] Preparation example

[0051] Preparation example 1

[0052] The modified castor oil is prepared from the following raw materials in parts by weight:

[0053] 50 parts of castor oil;

[0054] 7 parts of mercaptoethanol;

[0055] 4 parts of azobisisobutyronitrile;

[0056] 9 parts of glycerol;

[0057] 0.05 part of sodium hydroxide.

[0058] The modified castor oil is prepared through the following steps:

[0059] Mix castor oil and mercaptoethanol and put them into a reaction kettle. Pass nitrogen for protection and heat to 75°C. Add azobisisobutyronitrile and react for 3 hours. Then raise the temperature to 100°C and continue to react for 2 hours. Cool down and add ethyl acetate. Wash three times with brine and water respectively, and conduct drying treatment with anhydrous magnesium sulfate. Evaporate to remove ethyl acetate to obtain an intermediate;

[0060] Put the intermediate and glycerol into a mixing kettle. Add sodium hydroxide under stirring. Raise the temperature to 170°C and react for 1 hour under nitrogen protection to obtain modified castor oil.

[0061] Preparation Example 2

[0062] The modified castor oil is prepared from the following raw materials by weight:

[0063] 60 parts of castor oil;

[0064] 12 parts of mercaptoethanol;

[0065] 6 parts of azobisisobutyronitrile;

[0066] 12 parts of glycerol;

[0067] 0.1 part of sodium hydroxide.

[0068] The modified castor oil is prepared through the following steps:

[0069] Mix castor oil and mercaptoethanol and put them into a reaction kettle. Pass nitrogen for protection and heat to 80°C. Add azobisisobutyronitrile and react for 4 hours. Then raise the temperature to 105°C and continue to react for 2.5 hours. Cool down and add ethyl acetate. Wash three times with brine and water respectively, and conduct drying treatment with anhydrous magnesium sulfate. Evaporate to remove ethyl acetate to obtain an intermediate;

[0070] Put the intermediate and glycerol into a mixing kettle. Add sodium hydroxide under stirring. Raise the temperature to 180°C and react for 2 hours under nitrogen protection to obtain modified castor oil.

[0071] Preparation Example 3

[0072] The non-crystalline polyol containing a benzene ring structure is made from the following raw materials:

[0073] Adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, and their molar ratio is adipic acid:terephthalic acid:trimellitic anhydride:neopentyl glycol = 3:1:0.8:6;

[0074] p-Toluenesulfonic acid, with a mass of 300 ppm of the total acid mass;

[0075] Triphenyl phosphite, with a mass of 100 ppm of the total acid mass.

[0076] The non-crystalline polyol containing a benzene ring structure is obtained through the following steps:

[0077] Adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid, and triphenyl phosphite are put into a polymerization kettle. Under nitrogen protection, the temperature is raised to 170°C. After maintaining the temperature for dehydration of 60%, the temperature is continuously raised in units of 10°C. When the temperature reaches 220°C, insulation is started and the acid value is measured. When the acid value of the material is lower than 15 mgKOH / g, vacuum pumping is started, and the temperature is maintained at 220°C. When the acid value ≤ 2 mgKOH / g and the hydroxyl value is between 30 - 100 mgKOH / g, the reaction is stopped, the temperature is lowered, and the material is discharged to obtain a non-crystalline polyol containing a benzene ring structure.

[0078] Preparation Example 4

[0079] The non-crystalline polyol containing a benzene ring structure is made from the following raw materials:

[0080] Adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, and their molar ratio is adipic acid:terephthalic acid:trimellitic anhydride:neopentyl glycol = 3.5:1:1:9;

[0081] p-Toluenesulfonic acid, with a mass of 600 ppm of the total acid mass;

[0082] Triphenyl phosphite, with a mass of 200 ppm of the total acid mass.

[0083] The non-crystalline polyol containing a benzene ring structure is prepared through the following steps:

[0084] Adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid, and triphenyl phosphite are put into a polymerization kettle. Under nitrogen protection, the temperature is raised to 200°C. After maintaining the temperature for dehydration of 70%, the temperature is continuously raised in units of 10°C. When the temperature reaches 230°C, insulation is started and the acid value is measured. When the acid value of the material is lower than 15 mgKOH / g, vacuum pumping is started, and the temperature is maintained at 230°C. When the acid value ≤ 2 mgKOH / g and the hydroxyl value is between 30 - 100 mgKOH / g, the reaction is stopped, the temperature is lowered, and the material is discharged to obtain a non-crystalline polyol containing a benzene ring structure.

[0085] Example

[0086] Example 1

[0087] The waterproof and sealing chip hot melt adhesive comprises the following raw materials in parts by weight:

[0088] 20 parts of crystalline polyol, specifically polyhexamethylene adipate diol with a molecular weight of 3000 is selected;

[0089] 30 parts of non-crystalline polyol containing a benzene ring structure, specifically polyester polyol of phthalic acid / neopentyl glycol with a molecular weight of 1000 is selected;

[0090] 2 parts of castor oil;

[0091] 10 parts of aromatic diisocyanate, specifically diphenylmethane diisocyanate is selected;

[0092] 2 parts of 3-isocyanatopropyltriethoxysilane;

[0093] 0.2 part of catalyst, specifically dibutyltin dilaurate is selected;

[0094] 4 parts of terpene phenolic resin, purchased from Nantong Runfeng Petrochemical Co., Ltd.;

[0095] 1 part of antioxidant, specifically antioxidant 1010 is selected.

[0096] The preparation method of the waterproof and sealed chip hot melt adhesive comprises the following steps:

[0097] Put the crystalline polyol, non-crystalline polyol with benzene ring structure, castor oil and terpene phenolic resin into the reaction kettle, heat to 100 °C, and carry out vacuum dehydration for 2 h under stirring, and the vacuum degree is -0.01 MPa;

[0098] Cool down to 70 °C, add the catalyst and aromatic isocyanate into the reaction kettle, protect with nitrogen, raise the temperature and react at 80 °C for 2 h; put 3-isocyanatopropyltrimethoxysilane and antioxidant into the reaction kettle, stir and mix at 115 °C for 0.5 h under nitrogen protection, carry out vacuum degassing for 1 h, discharge the material, and seal and package under nitrogen protection.

[0099] Example 2

[0100] The waterproof and sealed chip hot melt adhesive comprises the following raw materials in parts by weight:

[0101] 35 parts of crystalline polyol, specifically poly(1,4-butylene adipate) diol with a molecular weight of 2000 is selected;

[0102] 45 parts of non-crystalline polyol with benzene ring structure, specifically polyester polyol of adipic acid / isophthalic acid / hexanediol with a molecular weight of 1500 is selected;

[0103] 7 parts of castor oil;

[0104] 18 parts of aromatic diisocyanate, specifically toluene diisocyanate is selected;

[0105] 4 parts of 3-isocyanatopropyltriethoxysilane;

[0106] 0.5 part of catalyst, specifically triethylenediamine is selected;

[0107] 9 parts of terpene phenolic resin, purchased from Nantong Runfeng Petrochemical Co., Ltd.;

[0108] 2 parts of antioxidant, specifically antioxidant 1076 is selected.

[0109] The preparation method of the waterproof and sealed chip hot melt adhesive comprises the following steps:

[0110] Put the crystalline polyol, the non-crystalline polyol with a benzene ring structure, castor oil, and terpene phenolic resin into a reaction kettle, heat to 130 °C, and carry out vacuum dehydration for 3 h under stirring, with the vacuum degree being -0.05 MPa;

[0111] Cool down to 75 °C, add a catalyst and an aromatic isocyanate into the reaction kettle, protect with nitrogen, heat up and react at 90 °C for 3 h; put 3-isocyanatopropyltrimethoxysilane and an antioxidant into the reaction kettle, stir and mix at 125 °C for 1 h under nitrogen protection, carry out vacuum defoaming for 1.5 h, discharge the material, and seal and package under nitrogen protection.

[0112] Example 3

[0113] The waterproof and sealed chip hot melt adhesive comprises the following raw materials in parts by weight:

[0114] 28 parts of crystalline polyol, specifically poly-2,3-dimethyl-2,3-butanediol with a molecular weight of 2000 is selected;

[0115] 38 parts of non-crystalline polyol with a benzene ring structure, specifically polyester polyol of isophthalic acid / hexanediol / neopentyl glycol with a molecular weight of 2000 is selected;

[0116] 5 parts of castor oil;

[0117] 13 parts of aromatic diisocyanate, specifically 8 parts of carbodiimide-modified diphenylmethane diisocyanate and 5 parts of diphenylmethylene diisocyanate are selected;

[0118] 3 parts of 3-isocyanatopropyltriethoxysilane;

[0119] 0.4 part of catalyst, specifically 0.2 part of dibutyltin dilaurate and 0.2 part of dimorpholinodiethyl ether are selected;

[0120] 7 parts of terpene phenolic resin, purchased from Nantong Runfeng Petrochemical Co., Ltd.;

[0121] 1.5 parts of antioxidant, specifically antioxidant 168 is selected.

[0122] The preparation method of the waterproof and sealed chip hot melt adhesive comprises the following steps:

[0123] Put the crystalline polyol, the non-crystalline polyol with a benzene ring structure, castor oil, and terpene phenolic resin into a reaction kettle, heat to 110 °C, and carry out vacuum dehydration for 2.5 h under stirring, with the vacuum degree being -0.03 MPa;

[0124] Cool down to 72 °C, add a catalyst and an aromatic isocyanate into the reaction kettle, protect with nitrogen, and heat up to 85 °C for reaction for 2.5 h;

[0125] Put 3-isocyanatopropyltrimethoxysilane and an antioxidant into the reaction kettle, stir and mix at 120 °C for 1 h under nitrogen protection, carry out vacuum defoaming for 1 h, discharge the material, and seal and package under nitrogen protection.

[0126] Example 4

[0127] The difference between this example and Example 1 lies in that the raw materials of the waterproof and sealed chip hot melt adhesive are different.

[0128] The castor oil in this example is the modified castor oil prepared in Preparation Example 1.

[0129] Example 5

[0130] The difference between this example and Example 1 lies in that the raw materials of the waterproof and sealed chip hot melt adhesive are different.

[0131] The castor oil in this example is the modified castor oil prepared in Preparation Example 2.

[0132] Example 6

[0133] The difference between this example and Example 1 lies in that the raw materials of the waterproof and sealed chip hot melt adhesive are different.

[0134] The non-crystalline polyol with a benzene ring structure in this example is the non-crystalline polyol with a benzene ring structure prepared in Preparation Example 3.

[0135] Example 7

[0136] The difference between this example and Example 1 lies in that the raw materials of the waterproof and sealed chip hot melt adhesive are different.

[0137] The non-crystalline polyol with a benzene ring structure in this example is the non-crystalline polyol with a benzene ring structure prepared in Preparation Example 4.

[0138] Example 8

[0139] The difference between this example and Example 1 lies in that the raw materials of the waterproof and sealed chip hot melt adhesive are different.

[0140] The castor oil in this example is the modified castor oil prepared in Preparation Example 2, and the non-crystalline polyol with a benzene ring structure in this example is the non-crystalline polyol with a benzene ring structure prepared in Preparation Example 3.

[0141] Comparative Example

[0142] Comparative Example 1

[0143] The difference between this comparative example and Example 1 lies in that the raw materials of the waterproof sealing chip hot melt adhesive are different.

[0144] In the raw materials of the hot melt adhesive in this comparative example, castor oil is not added.

[0145] Comparative Example 2

[0146] The difference between this comparative example and Example 1 lies in that the raw materials of the waterproof sealing chip hot melt adhesive are different.

[0147] In the raw materials of the hot melt adhesive in this comparative example, 3-isocyanatopropyltriethoxysilane is not added.

[0148] Comparative Example 3

[0149] The difference between this comparative example and Example 1 lies in that the raw materials of the waterproof sealing chip hot melt adhesive are different.

[0150] In the raw materials of the hot melt adhesive in this comparative example, the polyol is 50 parts of poly(1,6-hexanediol adipate) diol with a molecular weight of 3000.

[0151] Performance Test

[0152] Preparation of bonded specimens: After removing dust and oil from two standard bonding substrates, horizontal bonding is carried out with the hot melt adhesives prepared in Examples 1-8 and Comparative Examples 1-3 respectively. The bonding area is 12.5 mm × 25 mm, the adhesive application thickness is 0.2 mm. After bonding, curing is carried out under the conditions of 25°C and 50% RH. The complete curing conditions are: 25°C, 50% RH × 7 d.

[0153] The open time, bonding strength, high-temperature resistance and waterproofness of the hot melt adhesives prepared in each example and comparative example are tested.

[0154] Open time: Determined with reference to the standard HG / T 3716-2003;

[0155] Bonding strength: The shear tensile strength is determined with a tensile testing machine with reference to the standard GB / T 7124-2008;

[0156] High-temperature resistance: The bonded specimen after sizing and curing for 24 h is placed in a hot press mold at 160°C, hot pressed for 5 min, taken out and peeled, and the glue surface and glue are observed to determine whether there is softening and flowing of the glue layer;

[0157] Waterproofness: The water contact angle is tested with reference to the standard GB / T 30693-2014.

[0158] Please refer to Table 1 below for the comparison of all test data.

[0159] Table 1

[0160]

[0161] According to the data in Table 1, it can be seen that the moisture-curing polyurethane hot melt adhesive prepared in this application has excellent bonding strength, a relatively long open time, and at the same time has excellent high-temperature resistance and waterproofness, and can be used in high-temperature or humid environments to ensure the sealing performance and feasibility of the chip packaging structure.

[0162] Compared with Examples 1-3, in Examples 4-5, mercaptoethanol and glycerol were used to modify castor oil, and hydroxyl functional groups were introduced into castor oil, thereby increasing the crosslinking density of the polyurethane, increasing the bonding strength, and at the same time enhancing the water resistance.

[0163] Compared with Examples 1-3, in Examples 6-7, a non-crystalline polyol containing a benzene ring structure prepared by reacting adipic acid, terephthalic acid, trimellitic anhydride, and neopentyl glycol with a specific structure was used, making the soft segment structure of the polyurethane hot melt adhesive more random, with a longer open time and higher bonding strength.

[0164] Compared with Example 1, in Comparative Examples 1-3, castor oil, 3-isocyanatopropyltriethoxysilane, and the non-crystalline polyol containing a benzene ring structure were respectively missing from the raw materials of the polyurethane hot melt adhesive, resulting in a decline in the performance of the polyurethane hot melt adhesive, indicating the role of the raw material synergy on the performance of the polyurethane hot melt adhesive.

[0165] This specific implementation manner is only an interpretation of this application, and it is not a limitation of this application. After reading this specification, those skilled in the art can make modifications that do not contribute creatively to this specific implementation manner as needed, but as long as they are within the scope of the claims of this application, they are protected by the patent law.

Claims

1. A waterproof sealing chip hot melt adhesive, characterized in that: The invention comprises the following raw materials in parts by weight: 20-35 parts of crystalline polyol; 30-45 parts of non-crystalline polyol containing benzene ring structure; 2-7 parts of castor oil; 10-18 parts of aromatic diisocyanate; 2-4 parts of 3-isocyanatepropyltriethoxysilane; Catalyst 0.2-0.5 parts; 4-9 parts of terpene phenolic resin; 1-2 parts of antioxidants; The non-crystalline polyol containing a benzene ring structure is made of the following raw materials: adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid and triphenyl phosphite, wherein the molar ratio of adipic acid, terephthalic acid, trimellitic anhydride and neopentyl glycol is 3-3.5:1:0.8-1:6-9, and the masses of p-toluenesulfonic acid and triphenyl phosphite are 300-600ppm and 100-200ppm of the total acid mass, respectively.

2. A waterproof sealing chip hot melt adhesive according to claim 1, characterized in that: The castor oil is modified castor oil, and the modified castor oil is prepared from the following raw materials in parts by weight: 50-60 parts of castor oil; 7-12 parts of mercaptoethanol; 4-6 parts of azobisisobutyronitrile; Glycerin 9-12 parts; Sodium hydroxide 0.05-0.1 parts.

3. The waterproof sealing chip hot melt adhesive according to claim 1, characterized in that: The crystalline polyol is selected from one or more of poly 1,6-hexanediol adipate diol, poly 1,4-butylene adipate diol, polyethylene adipate diol, poly 2,3-dimethyl-2,3-butylene glycol.

4. The waterproof sealing chip hot melt adhesive according to claim 1, characterized in that: The aromatic diisocyanate is selected from one or more of diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, toluene diisocyanate, and diphenylmethylene diisocyanate.

5. The waterproof sealing chip hot melt adhesive according to claim 1, characterized in that: The catalyst is selected from one or more of dibutyltin dilaurate, triethylenediamine, and dimorpholinyl diethyl ether.

6. A method for preparing a waterproof sealing chip hot melt adhesive according to any one of claims 1 to 5, characterized in that: The following steps are involved: Put crystalline polyol, non-crystalline polyol containing benzene ring structure, castor oil and terpene phenolic resin into a reaction kettle, heat to 100-130°C, and vacuum dehydrate for 2-3h under stirring, with a vacuum degree of -0.01-0.05MPa; Cool down to 70-75℃, add catalyst and aromatic isocyanate into the reactor, pass nitrogen protection, raise the temperature to 80-90℃ and react for 2-3h; Add 3-isocyanatepropyltrimethoxysilane and antioxidant into the reaction kettle, stir and mix at 115-125° C. for 0.5-1 h under nitrogen protection, perform vacuum degassing for 1-1.5 h, discharge the material, and seal and package under nitrogen protection.

7. The method for preparing a waterproof sealing chip hot melt adhesive according to claim 6, characterized in that: When castor oil is modified castor oil, it is prepared by the following steps: Castor oil and mercaptoethanol are mixed and placed in a reaction kettle, and the mixture is heated to 75-80°C under nitrogen protection, and azobisisobutyronitrile is added to react for 3-4 hours, and the mixture is heated to 100-105°C and reacted for 2-2.5 hours, and ethyl acetate is added to the mixture, and the mixture is washed with brine and water, and dried with anhydrous magnesium sulfate, and the ethyl acetate is evaporated to obtain an intermediate; The intermediate and glycerol are added into a mixing kettle, sodium hydroxide is added under stirring, the temperature is raised to 170-180° C., and the mixture is reacted for 1-2 hours under nitrogen protection to obtain modified castor oil.

8. The method for preparing a waterproof sealing chip hot melt adhesive according to claim 6, characterized in that: The non-crystalline polyol containing a benzene ring structure is prepared by the following steps: Adipic acid, terephthalic acid, trimellitic anhydride, neopentyl glycol, p-toluenesulfonic acid and triphenyl phosphite are put into a polymerization kettle, and the temperature is raised to 170-200°C under nitrogen protection. After 60%-70% of water is removed by heat preservation, the temperature is continuously raised by 10°C. When the temperature reaches 220-230°C, heat preservation is started and the acid value is measured. When the acid value of the material is lower than 15 mgKOH / g, vacuuming is started and the temperature is maintained at 220°C-230°C. When the acid value is ≤2 mgKOH / g and the hydroxyl value is 30-100 mgKOH / g, the reaction is stopped, the temperature is lowered and the material is discharged to obtain a non-crystalline polyol containing a benzene ring structure.

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