Solvent-free polyurethane two-component adhesive for single composite film as well as preparation method and application of solvent-free polyurethane two-component adhesive

Abstract

The invention provides a solvent-free polyurethane two-component adhesive for a single composite film. The solvent-free polyurethane two-component adhesive comprises a component A and a component B, the component A is formed by carrying out first reaction on a first raw material system comprising polyisocyanate, first polyether polyol and a first hydroxyl-terminated polymer; the component B is formed by carrying out a second reaction on a second raw material system comprising polyester polyol with side groups, second polyether polyol, a second hydroxyl-terminated polymer and a coupling agent; the component A and the component B are compounded according to the molar ratio of functional groups-NCO to functional groups-OH being (1.8-2.5): 1. The solvent-free type polyurethane two-component adhesive has excellent peel strength; and the solvent-free polyurethane two-component adhesive does not contain a solvent, so that the interference of the solvent on the recovery process of the single-material composite membrane is avoided, and the white pollution is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane adhesives, and in particular to a solvent-free polyurethane two-component adhesive for a single-material composite film, and a preparation method and application thereof. Background Art

[0002] "Single-material" means single-material plastic packaging. With the improvement of environmental awareness, single-material plastic packaging has become a trend in the current packaging industry. Single-material plastic packaging not only helps to improve recycling efficiency, but also simplifies the types of packaging materials, reduces environmental pollution, and meets the needs of sustainable development. According to the report "The Future of the Single-Material Plastic Packaging Film Market in 2025" released by Smithers, the global single-material plastic packaging film market had a compound annual growth rate of 3.5% from 2015 to 2019; in 2019, the global single-material plastic packaging film market size was 20.44 million tons (US$55.9 billion), and it is expected that by 2025, the market size will grow to 26.03 million tons (about US$70.9 billion), with a compound annual growth rate of 3.9%.

[0003] As a new type of packaging material, single-material composite film is made by compounding the film of a single-material plastic packaging, thereby reducing the mixing of different film materials and improving the recycling rate. In the production of single-material composite film, adhesive is the key material for connecting the film layers. In particular, in the production process of single-material composite film, adhesive is needed to effectively combine the single-material plastic packaging film together to ensure the performance and stability of the single-material composite film. However, traditional single-material composite film production often uses solvent-based adhesives, which have some defects: (1) Solvent-based adhesives will volatilize harmful solvents during use, causing environmental pollution; (2) Due to the residual solvent in the solvent-based adhesive, the single-material composite film is difficult to recycle, which increases white pollution. Summary of the invention

[0004] The invention provides a solvent-free polyurethane two-component adhesive for a unitized composite film. The solvent-free polyurethane two-component adhesive has excellent peel strength. The solvent-free polyurethane two-component adhesive does not contain a solvent, thereby avoiding interference of the solvent on the recovery process of the unitized composite film and reducing white pollution.

[0005] The present invention also provides a method for preparing a solvent-free polyurethane two-component adhesive for a single-material composite film, by which a solvent-free polyurethane two-component adhesive for a single-material composite film with excellent peel strength can be prepared. The preparation method has a simple process and is suitable for wide promotion and application.

[0006] The present invention also provides a unitized composite film, comprising the above-mentioned solvent-free polyurethane two-component adhesive. The solvent-free polyurethane two-component adhesive has excellent peel strength for the unitized composite film and can achieve closed-loop recycling and reuse of the unitized composite film, thereby reducing costs, helping to reduce white pollution, and promoting the development of green packaging materials.

[0007] The first aspect of the present invention provides a solvent-free polyurethane two-component adhesive for a monolithic composite film, comprising a component A containing a functional group -NCO and a component B containing a functional group -OH;

[0008] The component A containing the functional group -NCO is formed by a first reaction of a first raw material system including a polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer;

[0009] The B component containing the functional group -OH is prepared by a second reaction of a second raw material system including a polyester polyol with a side group, a second polyether polyol, a second terminal hydroxyl polymer and a coupling agent, and the polyester polyol with a side group is prepared by an esterification polycondensation reaction of a third raw material system including a polyacid, a polyol with a side group and an antioxidant;

[0010] The component A containing the functional group -NCO and the component B containing the functional group -OH are compounded according to a molar ratio of the functional group -NCO to the functional group -OH of (1.8-2.5):1.

[0011] As described above, the solvent-free polyurethane two-component adhesive for the single-material composite film, in the first raw material system, the weight ratio of the polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer is (45-55): (44-59): (0-3), calculated by weight.

[0012] The solvent-free polyurethane two-component adhesive for the monolayer composite film as described above, wherein the polyisocyanate is at least one of toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, methylcyclohexyl diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate;

[0013] And / or, the first polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 3000 and polyoxypropylene triol having a number average molecular weight of 400 to 3000;

[0014] And / or, the first hydroxyl-terminated polymer is at least one of castor oil, tung oil, and hydroxyl-terminated polybutadiene.

[0015] The solvent-free polyurethane two-component adhesive for the single-material composite film as described above, in the second raw material system, the weight ratio of the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent is (40-60): (45-60): (1-6): (0.1-6), calculated by weight.

[0016] The solvent-free polyurethane two-component adhesive for the monolayer composite film as described above, wherein the second polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 2000 and polyoxypropylene triol having a number average molecular weight of 400 to 2000;

[0017] and / or, the second hydroxyl-terminated polymer is at least one of castor oil, tung oil, and hydroxyl-terminated polybutadiene;

[0018] And / or, the coupling agent is any one of KH550, KH560, KH570, KH580, and KH590.

[0019] The solvent-free polyurethane two-component adhesive for the single-material composite film as described above, in the third raw material system, the weight ratio of the polyacid, the polyol with a side group and the antioxidant is (45-54): (46-55): (0.008-0.01) in parts by weight.

[0020] The solvent-free polyurethane two-component adhesive for the monolayer composite film as described above, wherein the polyacid is at least one of maleic anhydride, adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride and sebacic acid;

[0021] And / or, the polyol with side groups is at least one of neopentyl glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol and 2-methyl-1,8-octanediol;

[0022] And / or, the antioxidant is at least one of triphenyl phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl) phosphite, and N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide.

[0023] The second aspect of the present invention provides a method for preparing the solvent-free polyurethane two-component adhesive for the monolayer composite film, comprising:

[0024] Adding polyisocyanate, a first polyether polyol and a first hydroxyl-terminated polymer into a first reactor for a first reaction to obtain a component A containing a functional group -NCO;

[0025] Adding a polyacid, a polyol with a side group and an antioxidant into a second reactor to carry out an esterification polycondensation reaction to obtain a polyester polyol with a side group;

[0026] Adding the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent into a third reactor for a second reaction to obtain a B component containing a functional group -OH;

[0027] The component A containing the functional group -NCO and the component B containing the functional group -OH are mixed evenly to obtain the solvent-free polyurethane two-component adhesive for the single-material composite film.

[0028] The preparation method of the solvent-free polyurethane two-component adhesive for the monolayer composite film as described above, the process of performing the first reaction is: adding polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer into the first reactor, first reacting at room temperature for 1h to 2h, then heating to 70°C to 90°C, reacting for 2h to 3h, to obtain the A component containing the functional group -NCO;

[0029] And / or, the process of the esterification polycondensation reaction is: adding a polyacid, a polyol with a side group and an antioxidant into a second reactor, heating to 150° C. to 160° C. for esterification reaction for 2 h to 3 h, and continuing to heat to 220° C. to 240° C. for esterification reaction until no water is produced, and the acid value is 15 mgKOH / g to 25 mgKOH / g; at 220° C. to 240° C., vacuuming to remove water, keeping warm for 0.5 h to 1.5 h, the acid value is 6 mgKOH / g to 10 mgKOH / g, and continuing to vacuumize for polycondensation reaction for 1 h to 3 h, the acid value is less than 2 mgKOH / g, and the hydroxyl value is 80 mgKOH / g to 160 mgKOH / g, so as to obtain the polyester polyol with a side group;

[0030] And / or, the process of performing the second reaction is: adding the polyester polyol with side groups, the second polyether polyol, and the second terminal hydroxyl polymer into a third reactor, first reacting at 60°C to 70°C for 1h to 2h, then cooling to 50°C to 60°C, adding a coupling agent and stirring evenly to obtain the B component containing the functional group -OH.

[0031] A third aspect of the present invention provides a unitized composite film, comprising the above-mentioned solvent-free polyurethane two-component adhesive for the unitized composite film.

[0032] The solvent-free polyurethane two-component adhesive for the monolithic composite film provided by the present invention is prepared by a first reaction of a first raw material system including polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer to obtain a component A containing a functional group -NCO, and then a second reaction of a second raw material system including a polyester polyol with a side group, a second polyether polyol, a second terminal hydroxyl polymer and a coupling agent to obtain a component B containing a functional group -OH, and the component A and the component B are compounded according to a specific molar ratio of the functional group -NCO and the functional group -OH. The solvent-free polyurethane two-component adhesive for the monolithic composite film has excellent peel strength, and the solvent-free polyurethane two-component adhesive does not contain solvent, thereby avoiding the interference of solvents on the recovery process of the monolithic composite film, reducing white pollution, and can be widely promoted and applied. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Unless otherwise specified, the raw materials and reagents used in the following examples can be obtained from commercial sources; the processes used, unless otherwise specified, are conventional processes in the art.

[0035] It should be noted that, in the present invention, there are descriptions involving “first”, “second”, etc., and the descriptions of “first”, “second”, etc. are only used for descriptive purposes and therefore cannot be understood as limitations on the present invention.

[0036] The first aspect of the present invention provides a solvent-free polyurethane two-component adhesive for a monolithic composite film, comprising a component A containing a functional group -NCO and a component B containing a functional group -OH;

[0037] The component A containing the functional group -NCO is formed by a first reaction of a first raw material system including a polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer;

[0038] The B component containing the functional group -OH is prepared by a second reaction of a second raw material system including a polyester polyol with a side group, a second polyether polyol, a second terminal hydroxyl polymer and a coupling agent, and the polyester polyol with a side group is prepared by an esterification polycondensation reaction of a third raw material system including a polyacid, a polyol with a side group and an antioxidant;

[0039] The component A containing the functional group -NCO and the component B containing the functional group -OH are compounded according to the molar ratio of the functional group -NCO to the functional group -OH of (1.8-2.5):1.

[0040] The present invention performs a first reaction on a raw material system including polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer to prepare a component A containing a functional group -NCO, and then performs a second reaction on a second raw material system including a polyester polyol with a side group, a second polyether polyol, a second terminal hydroxyl polymer and a coupling agent to prepare a component B containing a functional group -OH; then, the component A containing a functional group -NCO and the component B containing a functional group -OH are compounded according to a molar ratio of the functional group -NCO to the functional group -OH of (1.8 to 2.5):1, so as to prepare the above-mentioned solvent-free polyurethane two-component adhesive for the single-material composite film. In the actual application process, the solvent-free polyurethane two-component adhesive still has excellent peel strength after aging; and the solvent-free polyurethane two-component adhesive does not contain solvent, thereby avoiding the interference of solvents on the recovery process of the single-material composite film, reducing white pollution, and can be widely promoted and applied.

[0041] In some embodiments, the molar ratio of the functional group -NCO to the functional group -OH may preferably be 2.0:1.

[0042] In a specific embodiment, in the first raw material system, the weight ratio of the polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer is (45-55): (44-59): (0-3) in parts by weight.

[0043] The present invention uses polyisocyanate as a hard segment skeleton and introduces a first polyether polyol as a chain extender to prepare a component A containing a functional group -NCO. The present invention uses the chain segment length of the first polyether polyol to control polarity, so that the solvent-free polyurethane two-component adhesive for a single-material composite film prepared by mixing the component A containing a functional group -NCO and the component B containing a functional group -OH can be coated on substrates with different polarities (BOPE / PE, BOPP / CPP, BOPET / PET).

[0044] When the weight ratio of the polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer is within the above range, component A containing the functional group -NCO can be prepared, which is beneficial for using component A to prepare a solvent-free polyurethane two-component adhesive for a single-material composite film with excellent peel strength.

[0045] Illustratively, in the first raw material system, the weight ratio of the polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer may be any one of 46:54:0, 48:52:0, 45:52:3, 46:52:2, 45:44:0 and 55:59:3, or a range consisting of any three thereof.

[0046] In a specific embodiment, the polyisocyanate is at least one of toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, methylcyclohexyl diisocyanate, xylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; and / or the first polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 3000 and polyoxypropylene triol having a number average molecular weight of 400 to 3000; and / or the first terminal hydroxyl polymer is at least one of castor oil, tung oil, and terminal hydroxyl polybutadiene.

[0047] When the above substances are used for the first reaction, component A containing the functional group -NCO can be fully prepared.

[0048] In a specific embodiment, in the second raw material system, the weight ratio of the polyester polyol with pendant groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent is (40-60): (45-60): (1-6): (0.1-6) in parts by weight.

[0049] The present invention utilizes the second polyether polyol to reduce the viscosity of -OH, improve the leveling property of the B component, introduce more ether bonds, and reduce the polarity of the B component.

[0050] When the weight ratio of the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent is within the above range, a component B containing a functional group -OH can be prepared, which is beneficial for using the component B to prepare a solvent-free polyurethane two-component adhesive for a monolayer composite film with excellent peel strength.

[0051] Illustratively, in the second raw material system, the weight ratio of the polyester polyol with pendant groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent can be any one of 40:55:5:0.2, 50:45:5:0.2, 50:45:5:0.1 and 45:50:5:0.5, and a range consisting of any four of them.

[0052] In a specific embodiment, the second polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 2000 and polyoxypropylene triol having a number average molecular weight of 400 to 2000 and / or, the second terminal hydroxyl polymer is at least one of castor oil, tung oil, and terminal hydroxyl polybutadiene and / or, and the coupling agent is any one of KH550, KH560, KH570, KH580, and KH590.

[0053] In a specific embodiment, in the third raw material system, the weight ratio of the polyacid, the polyol with a pendant group and the antioxidant is (45-54): (46-55): (0.008-0.01) in parts by weight.

[0054] The present invention introduces a polyol with a side group to prepare a polyester polyol with a side group. The polyester polyol with a side group can be used to control the polarity, so that the solvent-free polyurethane two-component adhesive for a single-material composite film prepared by mixing a B component containing a functional group -OH with an A component containing a functional group -NCO can be coated on substrates with different polarities (BOPE / PE, BOPP / CPP, BOPET / PET).

[0055] When the weight ratio of the polyacid, the polyol with pendant groups and the antioxidant is within the above range, more polyester polyol with pendant groups can be prepared.

[0056] In a specific embodiment, the polyacid is at least one of maleic anhydride, adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride, and sebacic acid; and / or the polyol with a side group is neopentyl glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,2,4-trimethyl- At least one of 1,3-pentanediol and 2-methyl-1,8-octanediol; and / or, the antioxidant is at least one of triphenyl phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl alcohol ester, tris(2,4-di-tert-butylphenyl) phosphite, N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide.

[0057] When the above substances are used for the second reaction, a polyester polyol with a side group can be prepared. The second aspect of the present invention provides a method for preparing a solvent-free polyurethane two-component adhesive for a single-material composite film, comprising:

[0058] Adding polyisocyanate, a first polyether polyol and a first hydroxyl-terminated polymer into a first reactor for a first reaction to obtain a component A containing a functional group -NCO;

[0059] Adding a polyacid, a polyol with a side group and an antioxidant into a second reactor to carry out an esterification polycondensation reaction to obtain a polyester polyol with a side group;

[0060] Adding the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent into the third reactor for a second reaction to obtain a B component containing a functional group -OH;

[0061] The component A containing the functional group -NCO and the component B containing the functional group -OH are uniformly mixed to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0062] The present invention does not specifically limit the instruments or devices of the first reactor, the second reactor and the third reactor, and they can be selected according to specific needs. In some embodiments, the first reactor can be a four-necked flask, the second reactor can be a four-necked round-bottomed flask, and the third reactor can be a reactor.

[0063] The invention can prepare a solvent-free polyurethane two-component adhesive for a single-material composite film with excellent peel strength through the preparation method. The preparation method has a simple process and is suitable for wide promotion and application.

[0064] In a specific embodiment, the process of carrying out the first reaction is: adding polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer into a first reactor, first reacting at room temperature for 1h to 2h, then heating to 70°C to 90°C, reacting for 2h to 3h, and obtaining component A containing a functional group -NCO.

[0065] In a specific embodiment, the process of carrying out the esterification polycondensation reaction is as follows: adding a polyacid, a polyol with a side group and an antioxidant into a second reactor, heating to 150°C to 160°C for esterification reaction for 2h to 3h, and continuing to heat to 220°C to 240°C for esterification reaction until no water is produced, and the acid value is 15mgKOH / g to 25mgKOH / g; at 220°C to 240°C, vacuuming to remove water, keeping warm for 0.5h to 1.5h, the acid value is 6mgKOH / g to 10mgKOH / g, and continuing to vacuumize for 1h to 3h for polycondensation reaction, the acid value is less than 2mgKOH / g, and the hydroxyl value is 80mgKOH / g to 160mgKOH / g, thereby obtaining a polyester polyol with a side group.

[0066] In a specific embodiment, the process of carrying out the second reaction is: adding the polyester polyol with a side group, the second polyether polyol, and the second terminal hydroxyl polymer into the third reactor, first reacting at 60°C to 70°C for 1h to 2h, then cooling to 50°C to 60°C, adding a coupling agent and stirring evenly to obtain component B containing a functional group -OH.

[0067] A third aspect of the present invention provides a unitized composite film, comprising the above-mentioned solvent-free polyurethane two-component adhesive for the unitized composite film.

[0068] The solvent-free polyurethane two-component adhesive of the present invention has excellent peel strength for the above-mentioned single-material composite film, and can realize closed-loop recycling and reuse of the single-material composite film, thereby reducing costs, being beneficial to reducing white pollution, and promoting the development of green packaging materials.

[0069] The present invention is further described below through specific embodiments.

[0070] Example 1

[0071] In this embodiment, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0072] (1) By weight, 46 parts of polyoxypropylene glycol with a number average molecular weight of 1000 were added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 19 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) were added to react for 1 hour, and then the temperature was raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0073] (2) According to the weight percentage, under the protection of nitrogen, 54 parts of phthalic anhydride, 23 parts of 2-methyl-1,3-propanediol, 23 parts of neopentyl glycol and 0.01 parts of tris(2,4-di-tert-butylphenyl)phosphite were added into a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 hours until water was produced. The temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction until no more water was produced. The acid value was 18. 1mgKOH / g; at 230°C, vacuumize and remove water from -0.01MPa to -0.05MPa at a pressure rate of -0.01MPa / 30min, keep warm for 1.5h, the acid value is 7.5mgKOH / g, continue to vacuumize to -0.1MPa for condensation reaction for 3h, the acid value is 0.25mgKOH / g, the hydroxyl value is 140mgKOH / g, and a polyester polyol with a side group is obtained;

[0074] Polyoxypropylene diol with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were respectively vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0075] By weight, 40 parts of the above polyester polyol with side groups, 50 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.2 parts of coupling agent KH560 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0076] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0077] Example 2

[0078] In this embodiment, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0079] (1) By weight, 42 parts of polyoxypropylene glycol with a number average molecular weight of 2000 and 6 parts of polyoxypropylene glycol with a number average molecular weight of 400 were added to a four-necked flask, vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, cooled to room temperature, and then 19 parts of MDI (2,4'-diphenylmethane diisocyanate) and 33 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) were added to react for 1 h, and then the temperature was raised to 80° C. and reacted for 2 h to obtain a component A containing a functional group -NCO;

[0080] (2) In parts by weight, under the protection of nitrogen, 54 parts of phthalic anhydride, 23 parts of 2-methyl-1,3-propanediol, 23 parts of 2-ethyl-1,3-hexanediol and 0.01 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added to a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 h until water was produced, and the temperature was further raised to 230°C at a rate of 5°C / 30 min for esterification reaction until no more water was produced. Water, the acid value is 17.7 mgKOH / g; at 230°C, vacuumize and remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, keep warm for 1.5 hours, the acid value is 7.8 mgKOH / g, continue to vacuumize to -0.1 MPa for condensation reaction for 3 hours, the acid value is 1.05 mgKOH / g, the hydroxyl value is 138 mgKOH / g, and a polyester polyol with a side group is obtained;

[0081] Polyoxypropylene diol with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were respectively vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0082] By weight, 50 parts of the above polyester polyol with side groups, 40 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.2 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0083] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0084] Example 3

[0085] In this embodiment, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0086] (1) By weight, 40 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 5 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 3 parts of castor oil are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 17 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0087] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 19 parts of 2-methyl-1,3-propanediol, 36 parts of 2-butyl-2-ethyl-1,3-propanediol and 0.008 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added to a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 hours until water was produced, and the temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction. until no more water is produced, the acid value is 17.3 mgKOH / g; at 230°C, vacuumize and remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, keep warm for 1 hour, the acid value is 7.8 mgKOH / g, continue to vacuumize to -0.1 MPa for condensation reaction for 3 hours, the acid value is 0.3 mgKOH / g, the hydroxyl value is 130 mgKOH / g, and a polyester polyol with a side group is obtained;

[0088] Polyoxypropylene diol with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were respectively vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0089] By weight, 50 parts of the above polyester polyol with side groups, 40 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.1 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0090] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0091] Example 4

[0092] In this embodiment, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0093] (1) By weight, 42 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 4 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 2 parts of terminal hydroxyl polybutadiene are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 33 parts of MDI (2,4'-diphenylmethane diisocyanate) and 19 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0094] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 19 parts of 2-ethyl-1,3-hexanediol, 36 parts of neopentyl glycol and 0.009 parts of triphenyl phosphite were added to a four-necked round-bottom flask, and the temperature was raised to 150° C. for esterification reaction for 2 hours until water was discharged, and the temperature was further raised to 230° C. at a heating rate of 5° C. / 30 min for esterification reaction until no water was discharged, and the acid value was 19.4 mgKOH / g; at 230° C., vacuum was applied to remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, and the temperature was kept for 1 hour, and the acid value was 6.9 mgKOH / g; the vacuum was further applied to -0.1 MPa for polycondensation reaction for 3 hours, and the acid value was 0.92 mgKOH / g, and the hydroxyl value was 132 mgKOH / g, to obtain a polyester polyol with a side group;

[0095] A mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0096] By weight, 45 parts of the above polyester polyol with side groups, 45 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.1 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0097] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0098] Comparative Example 1

[0099] In this comparative example, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0100] (1) By weight, 40 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 5 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 3 parts of castor oil are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 17 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0101] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 55 parts of diethylene glycol and 0.008 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate were added to a four-necked round-bottom flask, the temperature was raised to 150°C for esterification reaction for 2 hours until water was discharged, the temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction until no water was discharged, and the acid value was 17.3 mgKOH / g; at 230°C, vacuum was applied to remove water from -0.01MPa to -0.05MPa at a pressure rate of -0.01MPa / 30min, the temperature was kept for 1 hour, the acid value was 7.8 mgKOH / g, the vacuum was further applied to -0.1MPa for polycondensation reaction for 3 hours, the acid value was 0.3 mgKOH / g, and the hydroxyl value was 130 mgKOH / g, to obtain a linear polyester polyol;

[0102] Polyoxypropylene diol with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were respectively vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0103] By weight, 50 parts of the above-mentioned linear polyester polyol, 40 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.1 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0104] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0105] Comparative Example 2

[0106] In this comparative example, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0107] (1) By weight, 40 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 5 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 3 parts of castor oil are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 17 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0108] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 19 parts of 2-methyl-1,3-propanediol, 36 parts of 2-butyl-2-ethyl-1,3-propanediol and 0.008 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added to a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 hours until water was produced, and the temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction. until no more water is produced, the acid value is 17.3 mgKOH / g; at 230°C, vacuumize and remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, keep warm for 1 hour, the acid value is 7.8 mgKOH / g, continue to vacuumize to -0.1 MPa for condensation reaction for 3 hours, the acid value is 0.3 mgKOH / g, the hydroxyl value is 130 mgKOH / g, and a polyester polyol with a side group is obtained;

[0109] Polyoxypropylene diol with a number average molecular weight of 400, polyoxypropylene triol with a number average molecular weight of 450, and terminal hydroxyl polybutadiene were respectively vacuum dehydrated at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and cooled to room temperature for later use;

[0110] By weight, 80 parts of the above polyester polyol with side groups, 10 parts of polyoxypropylene diol with a number average molecular weight of 400, 5 parts of polyoxypropylene triol with a number average molecular weight of 450, and 5 parts of terminal hydroxyl polybutadiene were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.1 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0111] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0112] Comparative Example 3

[0113] In this comparative example, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0114] (1) By weight, 40 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 5 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 3 parts of castor oil are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 17 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0115] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 19 parts of 2-methyl-1,3-propanediol, 36 parts of 2-butyl-2-ethyl-1,3-propanediol and 0.008 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added to a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 hours until water was produced, and the temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction. until no more water is produced, the acid value is 17.3 mgKOH / g; at 230°C, vacuumize and remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, keep warm for 1 hour, the acid value is 7.8 mgKOH / g, continue to vacuumize to -0.1 MPa for condensation reaction for 3 hours, the acid value is 0.3 mgKOH / g, the hydroxyl value is 130 mgKOH / g, and a polyester polyol with a side group is obtained;

[0116] The hydroxy-terminated polybutadiene was vacuum dehydrated at a temperature of 120°C and a pressure of -0.1 MPa for 2 hours, and then cooled to room temperature for later use;

[0117] 50 parts of the above polyester polyol with side groups and 5 parts of terminal hydroxyl polybutadiene were added into a reaction kettle by weight, reacted at 70°C for 1 hour, then cooled to 55°C, and 0.1 parts of coupling agent KH550 were added and stirred well to obtain component B containing a functional group -OH;

[0118] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0119] Comparative Example 4

[0120] In this comparative example, a solvent-free polyurethane two-component adhesive for a single-material composite film is prepared by the following process, including:

[0121] (1) By weight, 40 parts of polyoxypropylene glycol with a number average molecular weight of 2000, 5 parts of polyoxypropylene glycol with a number average molecular weight of 400 and 3 parts of castor oil are added to a four-necked flask, and vacuum dehydrated for 2 hours at a temperature of 120° C. and a pressure of -0.1 MPa. After cooling to room temperature, 17 parts of MDI (2,4'-diphenylmethane diisocyanate) and 35 parts of MDI50 (a mixture of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate) are added and reacted for 1 hour, and then the temperature is raised to 80° C. and reacted for 2 hours to obtain a component A containing a functional group -NCO;

[0122] (2) According to the weight percentage, under the protection of nitrogen, 45 parts of maleic anhydride, 19 parts of 2-methyl-1,3-propanediol, 36 parts of 2-butyl-2-ethyl-1,3-propanediol and 0.008 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added to a four-necked round-bottom flask, and the temperature was raised to 150°C for esterification reaction for 2 hours until water was produced, and the temperature was further raised to 230°C at a heating rate of 5°C / 30min for esterification reaction. until no more water is produced, the acid value is 17.3 mgKOH / g; at 230°C, vacuumize and remove water from -0.01 MPa to -0.05 MPa at a pressure rate of -0.01 MPa / 30 min, keep warm for 1 hour, the acid value is 7.8 mgKOH / g, continue to vacuumize to -0.1 MPa for condensation reaction for 3 hours, the acid value is 0.3 mgKOH / g, the hydroxyl value is 130 mgKOH / g, and a polyester polyol with a side group is obtained;

[0123] Polyoxypropylene diol with a number average molecular weight of 400 and polyoxypropylene triol with a number average molecular weight of 450 were respectively subjected to vacuum dehydration at a temperature of 120° C. and a pressure of -0.1 MPa for 2 h, and then cooled to room temperature for later use;

[0124] By weight, 50 parts of the above polyester polyol with side groups, 40 parts of polyoxypropylene diol with a number average molecular weight of 400, and 5 parts of polyoxypropylene triol with a number average molecular weight of 450 were added to a reaction kettle, first reacted at 70° C. for 1 hour, then cooled to 55° C., 0.1 parts of coupling agent KH550 were added and stirred thoroughly to obtain component B containing a functional group -OH;

[0125] (3) Compounding component A containing a functional group -NCO and component B containing a functional group -OH according to a molar ratio of the functional group -NCO to the functional group -OH of 2.0:1, and mixing them evenly to obtain a solvent-free polyurethane two-component adhesive for a single-material composite film.

[0126] Performance Characterization

[0127] Peel strength: The single-material composite films of Examples 1 to 4 and Comparative Example 1 were coated on the substrate with solvent-free polyurethane two-component adhesive, the polyurethane dry composite adhesive of Comparative Example 2, the polyurethane composite adhesive of Comparative Example 3, and the polyurethane adhesive of Comparative Example 4, respectively, with the adhesive amount of 1.8-2.5 g / m 2 , compound the substrate to obtain a single-material composite film, put the single-material composite film into a 45°C aging room for 48 hours to obtain a test specimen, cut the test specimen according to the GB8808-1988 soft composite material T-peel strength test method, and test the T-peel strength of the test specimen on an XLW intelligent tensile testing machine;

[0128] Biaxially oriented polyethylene / polyethylene film (BOPE / PE film), biaxially oriented polypropylene / cast polypropylene film (BOPP / CPP film), and biaxially oriented polyethylene terephthalate / polyethylene terephthalate film (BOPET / PET film) were used as substrates, and BOPE / PE composite film, BOPP / CPP composite film, and BOPET / PET composite film were prepared according to the above method, and then the peel strength was tested according to the above method. The test results are shown in Table 1;

[0129] Table 1 Test results

[0130]

[0131] In the table, "PET substrate fracture" means that the BOPET / PET film cannot be peeled off, which shows that the peeling strength of the BOPET / PET film using the solvent-free polyurethane two-component adhesive for the single-material composite film provided by the present invention is extremely high.

[0132] As shown in Table 1, the solvent-free polyurethane two-component adhesive for single-material composite film prepared by the present invention has a peel strength of 1.58-2.53 N / 15 mm for BOPE / PE film, a peel strength of 1.05-1.48 N / 15 mm for BOPP / CPP film, and cannot be peeled for BOPET / PET film. This shows that the solvent-free polyurethane two-component adhesive for single-material composite film provided by the present invention has excellent peel strength.

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A solvent-free polyurethane two-component adhesive for a single-material composite film, characterized in that: It includes an A component containing a functional group -NCO and a B component containing a functional group -OH; The component A containing the functional group -NCO is formed by a first reaction of a first raw material system including a polyisocyanate, a first polyether polyol and a first terminal hydroxyl polymer; The B component containing the functional group -OH is prepared by a second reaction of a second raw material system including a polyester polyol with a side group, a second polyether polyol, a second terminal hydroxyl polymer and a coupling agent, and the polyester polyol with a side group is prepared by an esterification polycondensation reaction of a third raw material system including a polyacid, a polyol with a side group and an antioxidant; The component A containing the functional group -NCO and the component B containing the functional group -OH are compounded according to a molar ratio of the functional group -NCO to the functional group -OH of (1.8-2.5):

1.

2. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 1, characterized in that: In terms of weight, in the first raw material system, the weight ratio of the polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer is (45-55): (44-59): (0-3).

3. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 2, characterized in that: The polyisocyanate is at least one of toluene diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, methylcyclohexyl diisocyanate, xylylene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate; And / or, the first polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 3000 and polyoxypropylene triol having a number average molecular weight of 400 to 3000; And / or, the first hydroxyl-terminated polymer is at least one of castor oil, tung oil, and hydroxyl-terminated polybutadiene.

4. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 1, characterized in that: In terms of weight, in the second raw material system, the weight ratio of the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent is (40-60): (45-60): (1-6): (0.1-6).

5. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 4, characterized in that: The second polyether polyol is at least one of polyoxypropylene diol having a number average molecular weight of 400 to 2000 and polyoxypropylene triol having a number average molecular weight of 400 to 2000; and / or, the second hydroxyl-terminated polymer is at least one of castor oil, tung oil, and hydroxyl-terminated polybutadiene; And / or, the coupling agent is any one of KH550, KH560, KH570, KH580, and KH590.

6. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 1, characterized in that: In terms of parts by weight, in the third raw material system, the weight ratio of the polyacid, the polyol with a pendant group and the antioxidant is (45-54): (46-55): (0.008-0.01).

7. The solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 6, characterized in that: The polyacid is at least one of maleic anhydride, adipic acid, terephthalic acid, isophthalic acid, phthalic anhydride and sebacic acid; And / or, the polyol with side groups is at least one of neopentyl glycol, 1,2-propylene glycol, 2-methyl-1,3-propylene glycol, 2-butyl-2-ethyl-1,3-propylene glycol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol and 2-methyl-1,8-octanediol; And / or, the antioxidant is at least one of triphenyl phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, tris(2,4-di-tert-butylphenyl)phosphite, and N,N'-1,6-hexylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide.

8. The method for preparing the solvent-free polyurethane two-component adhesive for a single-material composite film according to any one of claims 1 to 7, characterized in that: include: Adding polyisocyanate, a first polyether polyol and a first hydroxyl-terminated polymer into a first reactor for a first reaction to obtain a component A containing a functional group -NCO; Adding a polyacid, a polyol with a side group and an antioxidant into a second reactor to carry out an esterification polycondensation reaction to obtain a polyester polyol with a side group; Adding the polyester polyol with side groups, the second polyether polyol, the second terminal hydroxyl polymer and the coupling agent into a third reactor for a second reaction to obtain a B component containing a functional group -OH; The component A containing the functional group -NCO and the component B containing the functional group -OH are mixed evenly to obtain the solvent-free polyurethane two-component adhesive for the single-material composite film.

9. The method for preparing the solvent-free polyurethane two-component adhesive for a single-material composite film according to claim 8, characterized in that: The process of the first reaction is: adding polyisocyanate, the first polyether polyol and the first terminal hydroxyl polymer into the first reactor, first reacting at room temperature for 1h to 2h, then heating to 70°C to 90°C and reacting for 2h to 3h, so as to obtain the A component containing the functional group -NCO; And / or, the process of the esterification polycondensation reaction is: adding a polyacid, a polyol with a side group and an antioxidant into a second reactor, heating to 150° C. to 160° C. for esterification reaction for 2 h to 3 h, and continuing to heat to 220° C. to 240° C. for esterification reaction until no water is produced, and the acid value is 15 mgKOH / g to 25 mgKOH / g; at 220° C. to 240° C., vacuuming to remove water, keeping warm for 0.5 h to 1.5 h, the acid value is 6 mgKOH / g to 10 mgKOH / g, and continuing to vacuumize for polycondensation reaction for 1 h to 3 h, the acid value is less than 2 mgKOH / g, and the hydroxyl value is 80 mgKOH / g to 160 mgKOH / g, so as to obtain the polyester polyol with a side group; And / or, the process of performing the second reaction is: adding the polyester polyol with side groups, the second polyether polyol, and the second terminal hydroxyl polymer into a third reactor, first reacting at 60°C to 70°C for 1h to 2h, then cooling to 50°C to 60°C, adding a coupling agent and stirring evenly to obtain the B component containing the functional group -OH.

10. A single-material composite membrane, characterized in that: The invention comprises the solvent-free polyurethane two-component adhesive for the monolayer composite membrane according to any one of claims 1 to 7.

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