Polyurethane type UV viscosity-reducing adhesive based on carboxyl-terminated polyester and preparation method thereof

Abstract

The invention relates to a carboxyl-terminated polyester-based polyurethane UV viscosity-reducing adhesive and a preparation method thereof, and belongs to the technical field of new materials. The polyurethane UV viscosity-reducing adhesive provided by the invention is used for wafer manufacturing. The preparation method comprises the following steps: dissolving itaconic acid and 1, 4-butanediol in a solvent, and carrying out a heating reaction under the action of a catalyst to prepare a carboxyl-terminated prepolymer; carrying out ring-opening reaction on the carboxyl-terminated prepolymer and glycidyl methacrylate under the action of a catalyst to prepare hydroxyl-terminated polyester; the preparation method comprises the following steps: reacting hydroxyl-terminated polyester with isocyanate, and introducing a chain extender and a photoinitiator to prepare the rapidly-cured UV viscosity-reducing adhesive. The polyurethane UV viscosity-reducing glue is coated on a polyolefin film, the peeling strength at 180 degrees before ultraviolet irradiation after curing is 23.21-30.29 N / 25 mm, and the peeling strength at 180 degrees after ultraviolet irradiation is 0.07-0.19 N / 25 mm. According to the invention, the carboxyl-terminated prepolymer and glycidyl methacrylate are subjected to a ring-opening reaction, the viscosity reducing effect after UV irradiation is significant due to increase of double bonds, the 180-degree peel strength after UV irradiation is reduced, and no adhesive residue and degumming are realized.

Description

Technical Field

[0001] The present invention belongs to the field of new material technology, and relates to UV viscosity-reducing glue (adhesive) technology in wafer manufacturing, and specifically relates to a polyurethane-type UV viscosity-reducing glue based on terminal carboxyl polyester and a preparation method thereof. Background Art

[0002] UV viscosity-reducing adhesive is a smart adhesive based on ultraviolet light response. It is composed of resin, photoinitiator and functional additives. It triggers photopolymerization reaction through UV irradiation, causing photodegradation or structural changes to reduce adhesion and achieve rapid curing, thus having the characteristics of "on-demand adhesion and separation". This material is widely used in the field of temporary fixation (film lamination, core loading) during electronic components such as wafer cutting, grinding, and transportation. It can ensure that the fixed wafer remains stable during the processing process and effectively reduce the occurrence of wafer breakage and flash. After processing is completed, the adhesive layer is irradiated with ultraviolet light to greatly reduce the adhesion, so that the adherend (such as protective film, wafer, etc.) can be easily and cleanly peeled off from the substrate, with almost no residual glue stains and no damage to the adherend or substrate surface.

[0003] Currently, most of the viscosity-reducing adhesives on the market use acrylates as the main component, with multifunctional monomers and photoinitiators added to form UV viscosity-reducing adhesives. Residual adhesive is easily produced after UV irradiation, and the peeling force before UV irradiation is too low to effectively fix electronic devices. Existing polyurethane-based viscosity-reducing adhesives have higher peel strength before UV irradiation and lower peel strength after UV irradiation, but the curing time required to achieve the higher peel strength before UV irradiation is longer, usually requiring 24 hours of curing. Summary of the Invention

[0004] In order to solve the problem that the aging time of polyurethane-type UV viscosity-reducing adhesive is too long to reach the required peel strength before UV irradiation, the present invention provides a polyurethane-type UV viscosity-reducing adhesive based on terminal carboxyl polyester, and at the same time, provides a preparation method of the polyurethane-type UV viscosity-reducing adhesive based on terminal carboxyl polyester.

[0005] The structural formula of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester is as follows:

[0006]

[0007] Among them, R1 is

[0008] R2 is

[0009] R3 is

[0010] R4 is

[0011] R5 is One of them.

[0012] The polyurethane UV viscosity-reducing adhesive has a 180° peel strength of 21.5 to 33.7 N / 25 mm before ultraviolet light irradiation, and a 180° peel strength of 0.05 to 0.5 N / 25 mm after ultraviolet light irradiation.

[0013] The preparation steps of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester are as follows:

[0014] S1. Dissolve itaconic acid and 1,4-butanediol monomers in a solvent, heat and react under the action of catalyst A and a polymerization inhibitor, add n-hexane and deionized water for precipitation after the reaction, and dry to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer with the following structural formula:

[0015]

[0016] The degree of polymerization n in the formula is 3 to 6;

[0017] The acid value of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 60 to 90 mgKOH / g and the molecular weight is 500 to 1000;

[0018] The molar ratio of itaconic acid to 1,4-butanediol is 1.0:1 to 1.2:1;

[0019] The solvent is xylene. When the usage of itaconic acid and 1,4-butanediol monomers is g by mass, the usage of xylene is 10 to 30 mL;

[0020] The catalyst A is a 732 type strongly acidic ion exchange resin, and the added amount is 0.05% to 2% of the sum of the mass of the itaconic acid and 1,4-butanediol;

[0021] The polymerization inhibitor is hydroquinone, and the amount added is 0.05% to 2% of the mass of the itaconic acid;

[0022] S2. Dissolve the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate monomer in a solvent, and heat to react under the action of catalyst B to obtain a hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester having the following structural formula:

[0023]

[0024] The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1.0:1 to 1.1:1;

[0025] The solvent is xylene, and the amount added is 1 to 2 times the mass of terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester in milliliters;

[0026] The catalyst B is aluminum acetylacetonate, and the amount added is 0.05% to 2% of the sum of the mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate;

[0027] S3. Slowly add isophorone diisocyanate and catalyst C to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, heat and react to obtain a polyurethane-based adhesive. The reaction formula is as follows:

[0028]

[0029] The amount of isophorone diisocyanate added is 1.1 to 1.5 times the molar number of epoxy groups in glycidyl methacrylate;

[0030] The catalyst C is dibutyltin dilaurate, and the added amount is 0.05% to 2% of the sum of the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate;

[0031] S4, adding a chain extender and a photoinitiator to the polyurethane base adhesive, heating the reaction, and obtaining a polyurethane type UV viscosity-reducing adhesive based on carboxyl-terminated polyester;

[0032] The chain extender is one of 1,4-butene diol, 1,4-butanediol, and 1,5-pentanediol, and the amount of the chain extender added is 2 to 10% of the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester;

[0033] The photoinitiator is one of 2,4,6-trimethylbenzoylphenyl phosphate, 2,4,6-trimethylbenzoylphenyl ethyl phosphate, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-tolyl acetone. The amount of the photoinitiator added is 1-5% of the mass of the polyurethane base glue.

[0034] Further preparation technology scheme is as follows:

[0035] In step S1, the reaction synthesis conditions are: heating to a temperature of 140-160° C. and keeping the temperature under a nitrogen atmosphere for 3-5 hours; heating to 170-190° C. and keeping the temperature under a nitrogen atmosphere for 5-8 hours.

[0036] In step S1, the washing conditions are: washing the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer three times with n-hexane and deionized water at 60-80°C in sequence.

[0037] In step S1, the vacuum drying conditions are: vacuum degree of -85 kPa, drying temperature of 50-60° C., and drying time of 12-24 h.

[0038] In step S2, the reaction synthesis conditions are as follows: heating to a temperature of 90-130° C. and keeping the temperature under a nitrogen atmosphere for 3-7 hours.

[0039] In step S3, the reaction synthesis conditions are: heating to a temperature of 50-90° C. and keeping the temperature under a nitrogen atmosphere for 3-6 hours.

[0040] In step S4, the reaction synthesis conditions are: heating to a temperature of 40-80° C. and keeping the temperature under a nitrogen atmosphere for 2-5 hours.

[0041] The beneficial technical effects of the present invention are embodied in the following aspects:

[0042] (1) The polyurethane-based UV viscosity-reducing adhesive of the present invention introduces an excess of carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, wherein the carboxyl groups at both ends provide polarity, thereby increasing the interaction between the silicon wafer and the PO polyolefin film and improving the bonding strength, so that the UV viscosity-reducing adhesive can be quickly matured. The carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is reacted with glycidyl methacrylate, which shortens the maturation time. The peel strength before UV irradiation can reach 27.1N / 25mm after 3 hours of maturation.

[0043] (2) The carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer prepared in the present invention has a high double bond density in the main chain, resulting in a high crosslinking density of the UV-sensitive adhesive after 60 seconds of UV irradiation, and the 180° peel strength can be reduced to 0.05N / 25mm. Because no multifunctional monomer is required, the UV-sensitive adhesive will not produce colloidal residue on the silicon wafer after UV irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the infrared spectrum of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer prepared in Example 1.

[0045] Figure 2 This is the 180° peel strength-displacement curve of the polyurethane-type UV viscosity-reducing adhesive based on terminal carboxyl polyester prepared in Example 3 before and after UV. DETAILED DESCRIPTION

[0046] Some specific embodiments are listed below to describe the present invention in detail.

[0047] Unless otherwise defined, all technical and scientific terms used in the present invention are consistent with the prior art knowledge of those skilled in the art and the description of the present invention. The present invention may also be implemented using any methods, devices and materials in the prior art that are similar or equivalent to the methods, devices and materials in the embodiments of the present invention.

[0048] Example 1

[0049] The preparation of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester is as follows:

[0050] (1) Preparation of carboxyl-terminated prepolymer

[0051] 15 g of itaconic acid, 9.45 g of 1,4-butanediol monomer, 0.25 g of 732 strong acid ion exchange resin, and 0.15 g of hydroquinone were weighed, and 20 mL of xylene was added to a 150 mL two-necked flask. Nitrogen was continuously introduced during the reaction process. The reaction was carried out at 130°C for 3 h, and then the temperature was increased to 180°C for 6 h to obtain a reaction product.

[0052] The reaction product was added to 300 mL of n-hexane and stirred for 5 minutes to precipitate, and then added to 500 mL of deionized water to precipitate to obtain a precipitate. The precipitate was dried in a vacuum oven at 55°C for 24 hours to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, the structural formula of which is as follows:

[0053]

[0054] The degree of polymerization n in the formula is 5. The obtained carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer has an acid value of 85 mgKOH / g and a molecular weight of 500 to 1000.

[0055] The molar ratio of itaconic acid and 1,4-butanediol is 1.1:1;

[0056] The amount of catalyst 732 type strong acid ion exchange resin added is 1% of the sum of the mass of itaconic acid and 1,4-butanediol;

[0057] The amount of hydroquinone added is 1% of the mass of itaconic acid.

[0058] Depend on Figure 1 The infrared spectrum of the prepolymer shows that the -1 C=C double bond appears, 1145cm -1 An ether bond appears at 1715 cm -1 The presence of a carbonyl group at the position of , proved that the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer was successfully synthesized.

[0059] (2) Preparation of hydroxyl-terminated polyester

[0060] 10 g of carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, 2.16 g of glycidyl methacrylate, and 0.12 g of aluminum acetylacetonate were added to 20 mL of xylene, nitrogen was introduced, and the mixture was reacted at 130° C. for 3 h to obtain hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester with the following structural formula:

[0061]

[0062] The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1:1;

[0063] The amount of xylene added is 1.4 times in milliliters the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester;

[0064] The addition amount of the catalyst aluminum acetylacetonate is 1% of the total mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate.

[0065] (3) Preparation of polyurethane-based adhesive

[0066] Slowly add 3.71g of isophorone diisocyanate to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, and then add 0.16g of dibutyltin dilaurate. React at 60°C for 3h under nitrogen protection to obtain a polyurethane base adhesive. The reaction formula is as follows:

[0067]

[0068] The amount of catalyst dibutyltin dilaurate added is 1% of the total mass of terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate;

[0069] The amount of isophorone diisocyanate added is 1.1 times the molar number of epoxy groups in glycidyl methacrylate.

[0070] (4) Preparation of polyurethane UV viscosity-reducing adhesive

[0071] 0.61 g of cis-2-butene-1,4-diol and 0.48 g of 2,4,6-trimethylbenzoylphenyl phosphate were weighed and added to the polyurethane-based adhesive, and reacted at 50° C. for 3 h to obtain a polyurethane-based UV viscosity-reducing adhesive based on terminal carboxyl polyester.

[0072] The structural formula of the polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester prepared in Example 1 is as follows:

[0073]

[0074] Among them, R1 is

[0075] R2 is

[0076] R3 is

[0077] R4 is

[0078] R5 is

[0079] The 180° peel strength before UV irradiation was 23.21 N / 25 mm, and the 180° peel strength after UV irradiation was 0.12 N / 25 mm.

[0080] Example 2

[0081] The preparation of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester is as follows:

[0082] (1) Preparation of carboxyl-terminated prepolymer

[0083] 15 g of itaconic acid, 9.90 g of 1,4-butanediol monomer, 0.25 g of 732 strong acid ion exchange resin, and 0.15 g of hydroquinone were weighed, and 20 mL of xylene was added to a 150 mL two-necked flask. Nitrogen was continuously introduced during the reaction process. The reaction was carried out at 130° C. for 3 h, and then the temperature was increased to 180° C. for 6 h to obtain a reaction product.

[0084] The reaction product was added to 300 mL of n-hexane and stirred for 5 minutes to precipitate, and then added to 500 mL of deionized water to precipitate to obtain a precipitate. The precipitate was dried in a vacuum oven at 55°C for 24 hours to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, the structural formula of which is as follows:

[0085]

[0086] The degree of polymerization n in the formula is 5. The obtained carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer has an acid value of 77 mgKOH / g and a molecular weight of 500 to 1000.

[0087] The molar ratio of itaconic acid to 1,4-butanediol is 1.05:1;

[0088] The amount of catalyst 732 type strong acid ion exchange resin added is 1% of the sum of the mass of itaconic acid and 1,4-butanediol;

[0089] The amount of hydroquinone added is 1% of the mass of itaconic acid.

[0090] (2) Preparation of hydroxyl-terminated polyester

[0091] 10 g of carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, 1.95 g of glycidyl methacrylate, and 0.06 g of aluminum acetylacetonate were added to 15 mL of xylene, nitrogen was introduced, and the mixture was reacted at 130° C. for 3 h to obtain hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester with the following structural formula:

[0092]

[0093] The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1:1;

[0094] The amount of xylene added is 1.1 times in milliliters the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester;

[0095] The addition amount of the catalyst aluminum acetylacetonate is 0.5% of the total mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate.

[0096] (3) Preparation of polyurethane-based adhesive

[0097] Slowly add 3.67g of isophorone diisocyanate to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, and then add 0.16g of dibutyltin dilaurate. React at 60°C for 3h under nitrogen protection to obtain a polyurethane base adhesive. The reaction formula is as follows:

[0098]

[0099] The amount of catalyst dibutyltin dilaurate added is 1% of the total mass of terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate;

[0100] The amount of isophorone diisocyanate added is 1.2 times the molar number of epoxy groups in glycidyl methacrylate.

[0101] (4) Preparation of polyurethane UV viscosity-reducing adhesive

[0102] 0.48 g of 1,5-pentanediol and 0.62 g of 2,4,6-trimethylbenzoylphenyl phosphate were weighed and added to the polyurethane-based adhesive, and reacted at 50° C. for 3 h to obtain a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester.

[0103] The structural formula of the polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester prepared in Example 2 is as follows:

[0104]

[0105] Among them, R1 is

[0106] R2 is

[0107] R3 is

[0108] R4 is

[0109] R5 is

[0110] The 180° peel strength before UV irradiation was 24.55 N / 25 mm, and the 180° peel strength after UV irradiation was 0.07 N / 25 mm.

[0111] Example 3

[0112] The preparation of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester is as follows:

[0113] (1) Preparation of carboxyl-terminated prepolymer

[0114] 15 g of itaconic acid, 10.19 g of 1,4-butanediol monomer, 0.25 g of 732 strong acid ion exchange resin, and 0.15 g of hydroquinone were weighed, and 20 mL of xylene was added to a 150 mL two-necked flask. Nitrogen was continuously introduced during the reaction. The reaction was carried out at 130° C. for 3 h, and then the temperature was increased to 180° C. for 6 h to obtain a reaction product.

[0115] The reaction product was added to 300 mL of n-hexane and stirred for 5 minutes to precipitate, and then added to 500 mL of deionized water to precipitate to obtain a precipitate. The precipitate was dried in a vacuum oven at 55°C for 24 hours to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, the structural formula of which is as follows:

[0116]

[0117] The degree of polymerization n in the formula is 5. The obtained carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer has an acid value of 73 mgKOH / g and a molecular weight of 500 to 1000.

[0118] The molar ratio of itaconic acid to 1,4-butanediol is 1.02:1;

[0119] The amount of catalyst 732 type strong acid ion exchange resin added is 1% of the sum of the mass of itaconic acid and 1,4-butanediol;

[0120] The amount of hydroquinone added is 1% of the mass of itaconic acid.

[0121] (2) Preparation of hydroxyl-terminated polyester

[0122] 10 g of carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, 1.68 g of glycidyl methacrylate, and 0.12 g of aluminum acetylacetonate were added to 15 mL of xylene, nitrogen was introduced, and the mixture was reacted at 130° C. for 3 h to obtain hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester with the following structural formula:

[0123]

[0124] The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1.1:1;

[0125] The amount of xylene added is 1.1 times in milliliters the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester;

[0126] The addition amount of the catalyst aluminum acetylacetonate is 1% of the total mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate.

[0127] (3) Preparation of polyurethane-based adhesive

[0128] Slowly add 3.19 g of isophorone diisocyanate to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, and then add 0.15 g of dibutyltin dilaurate. React at 60°C for 3 h under nitrogen protection to obtain a polyurethane base adhesive. The reaction formula is as follows:

[0129]

[0130] The amount of catalyst dibutyltin dilaurate added is 1% of the total mass of terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate;

[0131] The amount of isophorone diisocyanate added is 1.1 times the molar number of epoxy groups in glycidyl methacrylate.

[0132] (4) Preparation of polyurethane UV viscosity-reducing adhesive

[0133] 0.35 g of cis-2-butene-1,4-diol and 0.30 g of 2,4,6-trimethylbenzoylphenyl phosphate were weighed and added to the polyurethane-based adhesive, and reacted at 50° C. for 3 h to obtain a polyurethane-based UV viscosity-reducing adhesive based on terminal carboxyl polyester.

[0134] The structural formula of the polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester prepared in Example 3 is as follows:

[0135]

[0136] Among them, R1 is

[0137] R2 is

[0138] R3 is

[0139] R4 is

[0140] R5 is

[0141] The 180° peel strength before UV irradiation was 27.03 N / 25 mm, and the 180° peel strength after UV irradiation was 0.11 N / 25 mm.

[0142] Depend on Figure 2 It can be seen that the polyurethane UV viscosity-reducing adhesive prepared in Example 3 has an average 180° peeling force of about 28 N before UV treatment 3 hours after coating, and an average 180° peeling force after UV treatment is close to 0 N.

[0143] Example 4

[0144] The preparation of a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester is as follows:

[0145] (1) Preparation of carboxyl-terminated prepolymer

[0146] 15 g of itaconic acid, 10.29 g of 1,4-butanediol monomer, 0.25 g of 732 strong acid ion exchange resin, and 0.15 g of hydroquinone were weighed, and 20 mL of xylene was added to a 150 mL two-necked flask. Nitrogen was continuously introduced during the reaction process. The reaction was carried out at 130°C for 3 h, and then the temperature was increased to 180°C for 6 h to obtain a reaction product.

[0147] The reaction product was added to 300 mL of n-hexane and stirred for 5 minutes to precipitate, and then added to 500 mL of deionized water to precipitate to obtain a precipitate. The precipitate was dried in a vacuum oven at 55°C for 24 hours to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, the structural formula of which is as follows:

[0148]

[0149] The degree of polymerization n in the formula is 5. The obtained carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer has an acid value of 69 mgKOH / g and a molecular weight of 500 to 1000.

[0150] The molar ratio of itaconic acid to 1,4-butanediol is 1.01:1;

[0151] The amount of catalyst 732 type strong acid ion exchange resin added is 1% of the sum of the mass of itaconic acid and 1,4-butanediol;

[0152] The amount of hydroquinone added is 1% of the mass of itaconic acid.

[0153] (2) Preparation of hydroxyl-terminated polyester

[0154] 10 g of carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer, 1.59 g of glycidyl methacrylate, and 0.12 g of aluminum acetylacetonate were added to 15 mL of xylene, nitrogen was introduced, and the mixture was reacted at 130° C. for 3 h to obtain hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester with the following structural formula:

[0155]

[0156] The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1.1:1;

[0157] The amount of xylene added is 1.1 times in milliliters the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester;

[0158] The addition amount of the catalyst aluminum acetylacetonate is 1% of the total mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate.

[0159] (3) Preparation of polyurethane-based adhesive

[0160] Slowly add 3.56g of isophorone diisocyanate to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, and then add 0.15g of dibutyltin dilaurate. React at 70°C for 3h under nitrogen protection to obtain a polyurethane base adhesive. The reaction formula is as follows:

[0161]

[0162] The amount of catalyst dibutyltin dilaurate added is 1% of the total mass of terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate;

[0163] The amount of isophorone diisocyanate added is 1.3 times the molar number of epoxy groups in glycidyl methacrylate.

[0164] (4) Preparation of polyurethane UV viscosity-reducing adhesive

[0165] 0.23 g of 1,4-butanediol and 0.15 g of 2,4,6-trimethylbenzoylphenyl phosphate were weighed and added to the polyurethane-based adhesive, and reacted at 50° C. for 3 h to obtain a polyurethane-based UV viscosity-reducing adhesive based on terminal carboxyl polyester.

[0166] The structural formula of the polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester prepared in Example 4 is as follows:

[0167]

[0168] Among them, R1 is

[0169] R2 is

[0170] R3 is

[0171] R4 is

[0172] R5 is

[0173] The 180° peel strength before UV irradiation was 30.29 N / 25 mm, and the 180° peel strength after UV irradiation was 0.19 N / 25 mm.

[0174] Performance Testing

[0175] The 180° peel strength of the samples was tested using GB / T 2792-1998 as the test standard, with a specimen width of 25 mm and a length of 100 mm at a tensile rate of 300 mm / min. The 180° peel strength of the carboxyl-terminated polyester-based polyurethane UV-viscosity-reducing adhesives prepared in Examples 1-4 before and after UV curing after aging for 3 hours is shown in Table 1. As shown in Table 1, the carboxyl-terminated polyester-based polyurethane UV-viscosity-reducing adhesives of the present invention exhibit high pre-UV peel strength and low post-UV peel strength.

[0176] Table 1 180° peel strength of UV viscosity reducing adhesives prepared in Examples 1-4 before and after UV curing

[0177]

[0178]

[0179] It is easy for those skilled in the art to understand that the above embodiments 1-4 are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester, characterized in that: The structural formula of the polyurethane UV viscosity-reducing adhesive is as follows: Among them, R1 is R2 is R3 is R4 is R5 is One of the following; The polyurethane UV viscosity-reducing adhesive has a 180° peel strength of 23.21 to 30.29 N / 25 mm before ultraviolet light irradiation, and a 180° peel strength of 0.07 to 0.19 N / 25 mm after ultraviolet light irradiation.

2. The method for preparing a polyurethane-based UV viscosity-reducing adhesive based on carboxyl-terminated polyester according to claim 1, wherein: The preparation steps are as follows: S1. Dissolve itaconic acid and 1,4-butanediol monomers in a solvent, heat and react under the action of catalyst A and a polymerization inhibitor, add n-hexane and deionized water for precipitation after the reaction, and dry to obtain a carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer with the following structural formula: The degree of polymerization n in the formula is 3 to 6; The acid value of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 60 to 90 mgKOH / g and the molecular weight is 500 to 1000; The molar ratio of itaconic acid to 1,4-butanediol is 1.0:1 to 1.2:1; The solvent is xylene. When the usage of itaconic acid and 1,4-butanediol monomers is g by mass, the usage of xylene is 10 to 30 mL; The catalyst A is a 732 type strongly acidic ion exchange resin, and the added amount is 0.05% to 2% of the sum of the mass of the itaconic acid and 1,4-butanediol; The polymerization inhibitor is hydroquinone, and the amount added is 0.05% to 2% of the mass of the itaconic acid; S2. Dissolve the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate monomer in a solvent, and heat to react under the action of catalyst B to obtain a hydroxyl-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester having the following structural formula: The molar ratio of carboxyl group to glycidyl methacrylate in the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer is 1.0:1 to 1.1:1; The solvent is xylene, and the amount added is 1 to 2 times the mass of terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester in milliliters; The catalyst B is aluminum acetylacetonate, and the amount added is 0.05% to 2% of the sum of the mass of the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer and glycidyl methacrylate; S3. Slowly add isophorone diisocyanate and catalyst C to the hydroxy-terminated glycidyl methacrylate-itaconic acid-(1,4-butanediol) polyester, heat and react to obtain a polyurethane-based adhesive. The reaction formula is as follows: The amount of isophorone diisocyanate added is 1.1 to 1.5 times the molar number of epoxy groups in glycidyl methacrylate; The catalyst C is dibutyltin dilaurate, and the added amount is 0.05% to 2% of the sum of the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid (1,4-butanediol) polyester and isophorone diisocyanate; S4, adding a chain extender and a photoinitiator to the polyurethane base adhesive, heating the reaction, and obtaining a polyurethane type UV viscosity-reducing adhesive based on carboxyl-terminated polyester; The chain extender is one of 1,4-butene diol, 1,4-butanediol, and 1,5-pentanediol, and the amount of the chain extender added is 2 to 10% of the mass of the terminal hydroxyl methacrylate glycidyl itaconic acid-(1,4-butanediol) polyester; The photoinitiator is one of 2,4,6-trimethylbenzoylphenyl phosphate, 2,4,6-trimethylbenzoylphenyl ethyl phosphate, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-tolyl acetone. The amount of the photoinitiator added is 1-5% of the mass of the polyurethane base glue.

3. The preparation method according to claim 2, characterized in that: In step S1, the reaction synthesis conditions are: heating to a temperature of 140-160° C. and keeping the temperature under a nitrogen atmosphere for 3-5 hours; heating to 170-190° C. and keeping the temperature under a nitrogen atmosphere for 5-8 hours.

4. The preparation method according to claim 2, wherein: In step S1, the washing conditions are: washing the carboxyl-terminated itaconic acid-(1,4-butanediol) prepolymer three times with n-hexane and deionized water at 60-80°C in sequence.

5. The preparation method according to claim 2, wherein: In step S1, the vacuum drying conditions are: vacuum degree of -85 kPa, drying temperature of 50-60° C., and drying time of 12-24 h.

6. The preparation method according to claim 2, wherein: In step S2, the reaction synthesis conditions are as follows: heating to a temperature of 90-130° C. and keeping the temperature under a nitrogen atmosphere for 3-7 hours.

7. The preparation method according to claim 2, wherein: In step S3, the reaction synthesis conditions are: heating to a temperature of 50-90° C. and keeping the temperature under a nitrogen atmosphere for 3-6 hours.

8. The preparation method according to claim 2, wherein: In step S4, the reaction synthesis conditions are: heating to a temperature of 40-80° C. and keeping the temperature under a nitrogen atmosphere for 2-5 hours.

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