High-barrier fast-curing solvent-free polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a high-barrier fast-curing solvent-free polyurethane adhesive and a preparation method thereof, and belongs to the field of preparation of polyurethane adhesives. The adhesive is composed of a component A and a component B, the component A and the component B are used in cooperation according to the functional group molar ratio of-NCO:-OH = 1.1-1.9: 1, and the component A is a modified isocyanate adduct formed by reaction of modified polyester polyol and polyisocyanate; and the component B is a mixture of castor oil derivative polyol, modified polyester polyol and polyether polyol. According to the adhesive, through selection of raw material monomers, design of a molecular chain structure and a specific molecular weight size and regulation and control of a molecular proportion, higher reaction activity and excellent water and oxygen blocking performance are achieved. The high-barrier fast-curing adhesive is excellent in peel strength and can meet the actual application process requirements of the adhesive, so that the high-barrier fast-curing adhesive can be widely applied to the field of composite flexible packaging.

Description

Technical Field

[0001] The invention relates to the field of polyurethane adhesive preparation, and in particular to a high-barrier, fast-solidifying, solvent-free polyurethane adhesive for composite flexible packaging in the fields of food, daily necessities, medicines, etc., and a preparation method thereof. Background Art

[0002] Solvent-free polyurethane adhesives for composite flexible packaging do not contain organic solvents, have outstanding environmental protection and safety, low cost, high efficiency, and the comprehensive performance of the composite material is better than that of each single material. They have received widespread attention and are increasingly widely used. They are currently widely used in various fields such as food, daily necessities, medicines, agricultural products, industrial products, cosmetics, and electronic products.

[0003] With the rapid development of solvent-free lamination technology in recent years, solvent-free lamination technology is not only used in the lamination of ordinary products, but also gradually applied to the lamination of functional packaging materials. It is expected that the glue can also have a certain barrier function to reduce the excessive requirements for film materials. In addition, the increase in curing speed and the reduction in curing conditions can significantly expand the application range of glue. Therefore, solvent-free polyurethane adhesives still face severe challenges in expanding their application areas.

[0004] During the curing process, traditional solvent-free polyurethane adhesives usually need to be cured for a relatively long time in a high temperature or humidity environment, which obviously cannot meet the use requirements for certain materials or processes that require rapid curing. Therefore, the curing speed plays an important role in improving composite packaging materials. On the other hand, for composite packaging, especially in the fields of food, the function of blocking gases such as water and oxygen mainly relies on the improvement of composite materials and the combination of multiple materials. The proportion of adhesives in the entire composite packaging is not high, so it is difficult to play its role, but relying on adhesives to meet the improvement of high barrier functions is still the direction of development.

[0005] Therefore, how to provide a new solvent-free polyurethane adhesive that can achieve both high barrier properties and fast curing properties and better meet the current industrial production needs and environmental protection requirements is a problem that needs to be solved.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a high-barrier, fast-curing solvent-free polyurethane adhesive and a preparation method thereof, which can achieve both high-barrier and fast-curing properties, thereby improving the wide application of solvent-free adhesives in the field of composite films, and well solving the above-mentioned technical problems existing in the prior art.

[0008] The objective of the present invention is achieved through the following technical solutions:

[0009] A high-barrier, fast-solidifying, solvent-free polyurethane adhesive, comprising: a component A and a component B, wherein the component A and the component B are used in combination at a functional group molar ratio of -NCO:-OH=1.1-1.9:1, wherein the component A is a modified isocyanate adduct formed by the reaction of a modified polyester polyol and a polyisocyanate, and the NCO% mass percentage of the component A is 15%-27%;

[0010] The B component is a mixture of castor oil derivative polyol, modified polyester polyol and polyether polyol.

[0011] A method for preparing the high-barrier, fast-curing, solvent-free polyurethane adhesive of the present invention comprises the following preparation steps:

[0012] Prepare component A and component B respectively;

[0013] Preparation of component A:

[0014] First, the modified polyester polyol used in component A is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction;

[0015] Add polyisocyanate to the reaction kettle, keep the kettle temperature at 25-35°C, then add the modified polyester polyol used in component A, react at 70-80°C for 3-4 hours, then add polyisocyanate and react at 70°C for 2 hours, and cool to room temperature after the reaction to obtain component A;

[0016] Preparation of component B:

[0017] First, the modified polyester polyol used in component B is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction;

[0018] Add castor oil derivative polyol and the modified polyester polyol used for component B into the reaction kettle, keep the kettle temperature at 45-55°C, then add polyether polyol, start stirring, raise the kettle temperature to 65-75°C and react for 2-3 hours, and then cool to room temperature after the reaction to obtain component B;

[0019] The prepared component A and component B are used in combination according to the functional group molar ratio of -NCO:-OH=1.1-1.9:1 to prepare a high-barrier, fast-curing, solvent-free polyurethane adhesive.

[0020] Compared with the prior art, the high-barrier, fast-solidifying, solvent-free polyurethane adhesive and the preparation method thereof provided by the present invention have the following beneficial effects:

[0021] Since modified polyester polyols with independent molecular structure design are used in components A and B, the design structure advantages are fully utilized, and the polyisocyanate in component A and castor oil-derived polyols and polyether polyols are used in component B. This combination not only improves the bonding strength and durability of the adhesive, but also significantly improves the curing speed and barrier force. The present invention not only improves product performance and broadens application scenarios, but also conforms to the development trend of solvent-free polyurethane adhesives. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the specific content of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0023] First, the terms that may be used in this article are explained as follows:

[0024] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0025] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0026] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0027] The term "parts by mass" refers to the mass ratio relationship between multiple components. For example, if it is described that component X is x parts by mass and component Y is y parts by mass, then the mass ratio of component X to component Y is x:y. 1 part by mass can represent any mass, for example, 1 part by mass can be represented as 1 kg or 3.1415926 kg. The sum of the parts by mass of all components is not necessarily 100 parts, but can be greater than 100 parts, less than 100 parts or equal to 100 parts. Unless otherwise specified, the parts, proportions and percentages described herein are all measured by mass.

[0028] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, and preferred value in the numerical range, regardless of whether the range is explicitly stated; for example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges stated herein include both their end values ​​and all integers and fractions within the numerical range.

[0029] The scheme provided by the present invention is described in detail below. The contents not described in detail in the embodiments of the present invention belong to the prior art known to professionals in the field. If the specific conditions are not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturers are not specified in the reagents or instruments used in the embodiments of the present invention, they are all conventional products that can be purchased commercially.

[0030] The embodiment of the present invention provides a high-barrier, fast-curing, solvent-free polyurethane adhesive, comprising: a component A and a component B, wherein the component A and the component B are used in combination according to a functional group molar ratio of -NCO:-OH=1.1-1.9:1, wherein the component A is a modified isocyanate adduct formed by the reaction of a modified polyester polyol and a polyisocyanate, and the NCO% mass percentage of the component A is 15%-27%;

[0031] The B component is a mixture of castor oil derivative polyol, modified polyester polyol and polyether polyol.

[0032] Preferably, in the above adhesive, in the component A and the component B, the modified polyester polyol is a polyester polyol with a functionality of two or more, which is prepared by an esterification condensation reaction of a small molecule polyol and a small molecule polyacid.

[0033] Preferably, in the above adhesive, in the component A, the small molecule polyol in the polyester polyol with a functionality of two or more is at least one of ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, dipropylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,5-pentanediol, 1,4-cyclohexanediol, and glycerol;

[0034] In the component A, the small molecule polyacid in the polyester polyol with a functionality of two or more is at least one of isophthalic acid, phthalic acid, terephthalic acid, 1,4-succinic acid, 1,6-hexanedioic acid, sebacic acid, azelaic acid and lauric acid.

[0035] Preferably, in the above-mentioned adhesive, among the polyester polyols with a functionality of two or more in the A component, the small molecule polyols with a functionality of two or more in the small molecule polyols are selected from the group consisting of ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, dipropylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, and 2,2-dimethyl-1,3-propanediol, and their usage accounts for 50% to 100% of the total molar amount of the small molecule polyols.

[0036] Preferably, in the above adhesive, in the B component, the small molecule polyol in the polyester polyol with a functionality of two or more is at least one of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,6-hexanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, glycerol, and trimethylolpropane;

[0037] In the component B, the small molecular weight polyacid in the polyester polyol with a functionality of two or more is at least one of phthalic acid, terephthalic acid, 1,4-succinic acid, 1,6-hexanedioic acid, sebacic acid, azelaic acid and lauric acid.

[0038] Preferably, in the above-mentioned adhesive, the polyester polyol with a functionality of two or more in the B component and the small molecule polyol with a functionality of two or more in the small molecule polyol include one of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,6-hexanediol and 1,4-butanediol, and its amount accounts for 50% to 100% of the total molar amount of the small molecule polyol.

[0039] Preferably, in the above adhesive, in the component A and the component B, the phenylcyclic acid in the small molecule polyacid of the polyester polyol with a functionality of two or more accounts for 20% to 50% of the total molar amount of the small molecule polyacid.

[0040] Preferably, in the above adhesive, in the component B, each component is calculated by weight as follows:

[0041] 20-50 parts of castor oil derivative polyol;

[0042] 20-50 parts of modified polyester polyol;

[0043] 10-20 parts of polyether polyol.

[0044] Preferably, in the above adhesive, in the component A, the polyisocyanate is at least one of a mixture of diphenylmethane 4,4'-diisocyanate and diphenylmethane 2,4'-diisocyanate, toluene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate;

[0045] In the B component, the polyether polyol is one or a mixture of more than one of polyoxypropylene diol, polyoxypropylene triol, polytetrahydrofuran diol, and polyoxypropylene-ethylene oxide diol.

[0046] The embodiment of the present invention further provides a method for preparing the above-mentioned high-barrier fast-curing solvent-free polyurethane adhesive, comprising the following preparation steps:

[0047] Prepare component A and component B respectively;

[0048] Preparation of component A:

[0049] First, the modified polyester polyol used in component A is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction;

[0050] Add polyisocyanate to the reaction kettle, keep the kettle temperature at 25-35°C, then add the modified polyester polyol used in component A, react at 70-80°C for 3-4 hours, then add polyisocyanate and react at 70°C for 2 hours, and cool to room temperature after the reaction to obtain component A;

[0051] Preparation of component B:

[0052] First, the modified polyester polyol used in component B is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction;

[0053] Add castor oil derivative polyol and the modified polyester polyol used for component B into the reaction kettle, keep the kettle temperature at 45-55°C, then add polyether polyol, start stirring, raise the kettle temperature to 65-75°C and react for 2-3 hours, and then cool to room temperature after the reaction to obtain component B;

[0054] The prepared component A and component B are used in combination according to the functional group molar ratio of -NCO:-OH=1.1-1.9:1 to prepare a high-barrier, fast-curing, solvent-free polyurethane adhesive.

[0055] In summary, the modified polyester polyol used in component A and component B of the embodiment of the present invention adjusts the ratio of soft segment to hard segment and the molecular weight in the polymer segment through molecular structure design, so that the molecular chain still maintains relatively excellent microscopic motion activity and curing speed during the curing process, and the unique stacking and arrangement of molecular weight enables the adhesive to obtain relatively excellent barrier properties while maintaining high peel strength.

[0056] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with specific embodiments below.

[0057] Example 1

[0058] The present embodiment provides a high-barrier, fast-curing, solvent-free polyurethane adhesive, which is a solvent-free two-component polyurethane adhesive. The adhesive consists of component A and component B, wherein component A is a modified isocyanate adduct formed by the reaction of modified polyester polyol and polyisocyanate; component B is prepared by mixing castor oil derivative polyol, modified polyester polyol and polyether polyol;

[0059] The adhesive is formed by combining component A and component B at a functional group molar ratio of -NCO:-OH=1.6:1.

[0060] The preparation method of the adhesive comprises the following steps:

[0061] (I) Preparation of component A:

[0062] (11) Firstly, a modified polyester polyol is prepared, comprising:

[0063] (111) Raw materials: 0.8 mol of 2-methyl-1,3-propanediol, 0.5 mol of ethylene glycol, 0.2 mol of 2,2-dimethyl-1,3-propanediol, 0.5 mol of isophthalic acid, 0.3 mol of sebacic acid, and 0.2 mol of terephthalic acid;

[0064] (112) Preparation steps:

[0065] Add all small molecule polyol monomers (0.8 mol of 2-methyl-1,3-propanediol, 0.5 mol of ethylene glycol and 0.2 mol of 2,2-dimethyl-1,3-propanediol) into the polyester reactor, start stirring, mix evenly, add small molecule dibasic acid monomers (0.5 mol of isophthalic acid, 0.3 mol of sebacic acid and 0.2 mol of terephthalic acid), continue stirring, close the polyester reactor charging cover, heat up, and introduce nitrogen; the reactor temperature rises to about 150°C and water begins to flow out, control the temperature of the top of the fractionation tower at 100-105°C, continue heating and reacting, and the temperature in the reactor reaches about 240°C to produce the theoretical water output. After the water output is completed, keep warm for 2 hours and stop introducing nitrogen;

[0066] Take samples to test the acid value and control the acid value below 25; maintain the temperature in the kettle at 220-240°C, start to gradually evacuate the kettle, and take samples to test the hydroxyl value and acid value. The hydroxyl value reaches 190±5 and the acid value 2.0±1 is qualified; cool down and discharge the material to obtain the modified polyester polyol used for component A; its hydroxyl value is 190 and the acid value is 1.5.

[0067] (12) Synthesize component A (the amount of each component is in parts by weight):

[0068] Preparation: 20 parts of isophorone diisocyanate and 20 parts of toluene diisocyanate, keep the kettle temperature at 30±5°C, add 40 parts of the modified polyester polyol prepared above, react at 70°C for 3 hours, then add 20 parts of C-MDI, react at 70°C for 2 hours, and cool to room temperature to obtain component A. Test NCO% = 18.2%.

[0069] (II) Preparation of component B:

[0070] (21) First, a modified polyester polyol is prepared, comprising:

[0071] (211) Prepare: 0.9 mol of ethylene glycol, 0.4 mol of 1,4-butanediol, 0.1 mol of trimethylolpropane, 0.3 mol of terephthalic acid, and 0.7 mol of 1,4-butanediol;

[0072] (212) The modified polyester polyol was prepared in the same manner as the modified polyester polyol used to prepare component A in this embodiment. The hydroxyl value of the prepared modified polyester polyol was 180 and the acid value was 2.2.

[0073] (22) Synthesize component B (the amount of each component is in parts by weight):

[0074] Add 40 parts of the modified polyester polyol prepared above and 40 parts of castor oil derivative polyol into a reactor, maintain the reactor temperature at 50±5°C, then add 20 parts of polyoxypropylene triol (molecular weight 500), start stirring, raise the reactor temperature to 70±5°C, react for 3 hours, and cool to room temperature to obtain component B.

[0075] (III) The above-prepared component A and component B are mixed at a functional group molar ratio of -NCO:-OH=1.6:1.0 to prepare a high barrier fast-curing solvent-free polyurethane adhesive. The adhesive is used to compound VMPET / PE and matured at 40°C. The VMPET / PE layer of the composite film is peeled off at different time periods, and the peel strength is tested after covering. The time taken to have no peel strength is recorded as the actual curing time. The peel strength of the composite film after full curing is tested.

[0076] Example 2

[0077] This embodiment provides a high-barrier, fast-curing, solvent-free polyurethane adhesive, which consists of component A and component B, wherein component A is a modified isocyanate adduct formed by the reaction of modified polyester polyol and polyisocyanate; component B is prepared by mixing castor oil derivative polyol, modified polyester polyol and polyether polyol;

[0078] The component A and the component B can be combined to form the adhesive according to the functional group molar ratio of -NCO:-OH=1.6:1.

[0079] The preparation method of the adhesive comprises the following steps:

[0080] (I) Preparation of component A

[0081] (11) first preparing a modified polyester polyol, comprising

[0082] (111) Raw materials: 0.8 mol of diethylene glycol, 0.4 mol of 1,3-propylene glycol, 0.3 mol of 2-methyl-1,3-propanediol, 0.6 mol of isophthalic acid, 0.3 mol of 1,6-dipic acid, and 0.1 mol of azelaic acid;

[0083] (112) Preparation steps:

[0084] The preparation method can refer to the steps of preparing the modified polyester polyol used for component A in Example 1. The prepared modified polyester polyol has a hydroxyl value of 195 and an acid value of 2.3.

[0085] (12) Synthesize component A (the amount of each component is in parts by weight):

[0086] 10 parts of dicyclohexylmethane diisocyanate and 30 parts of toluene diisocyanate were added to a kettle at 30±5°C, 40 parts of modified polyester polyol were added, and the mixture was reacted at 80°C for 3 hours, and then 20 parts of C-MDI were added, and the mixture was reacted at 80°C for 2 hours, and then the mixture was cooled to room temperature to obtain component A. The test result showed that NCO% was 18.5%.

[0087] (II) Preparation of component B:

[0088] (21) Preparing a modified polyester polyol, comprising:

[0089] (211) Prepare: 1 mol of ethylene glycol, 0.4 mol of 1,6-hexanediol, 0.1 mol of trimethylolpropane, 0.5 mol of terephthalic acid, 0.3 mol of sebacic acid, and 0.2 mol of 1,6-hexanediol;

[0090] (212) Preparation of modified polyester: The preparation method can refer to the steps of preparing the modified polyester polyol of component A in Example 1. The hydroxyl value of the prepared modified polyester polyol is 175 and the acid value is 1.5.

[0091] (22) Synthesize component B (the amount of each component is in parts by weight):

[0092] Add 50 parts of modified polyester polyol and 30 parts of castor oil derivative polyol into the reaction kettle, maintain the kettle temperature at 50±5°C, add 20 parts of polyoxypropylene glycol (molecular weight 400), start stirring, raise the kettle temperature to 70±5°C, react for 3 hours, and cool to room temperature to obtain component B.

[0093] (III) Component A and component B are prepared according to the functional group molar ratio of -NCO:-OH=1.6:1.0 to form the adhesive. The adhesive is used to compound VMPET / PE and cured at 40°C. The VMPET / PE layer of the composite film is peeled off at different time periods, and the peel strength is tested after overlapping. The time taken to have no peel strength is recorded as the actual curing time. The peel strength of the composite film after full curing is tested.

[0094] Example 3

[0095] This embodiment provides a high-barrier, fast-curing, solvent-free polyurethane adhesive, which consists of component A and component B, wherein component A is prepared by reacting polyisocyanate and modified polyester polyol; component B is prepared by mixing polyester polyol and polyether polyol;

[0096] The component A and the component B can be combined to form the adhesive according to the functional group molar ratio of -NCO:-OH=1.7:1.

[0097] The preparation method of the adhesive comprises the following steps:

[0098] (I) Preparation of component A:

[0099] (11) Firstly, a modified polyester polyol is prepared, comprising:

[0100] (111) Raw materials: 0.8 mol dipropylene glycol, 0.4 mol ethylene glycol, 0.3 mol 1,5-pentanediol, 0.6 mol isophthalic acid, 0.3 mol azelaic acid, 0.1 mol 1,4-succinic acid;

[0101] (112) Preparation steps:

[0102] The preparation method can refer to the steps of preparing the modified polyester polyol used for component A in Example 1. The hydroxyl value of the prepared modified polyester polyol is 193 and the acid value is 2.7.

[0103] (22) Synthesize component A (the amounts of each component are parts by weight):

[0104] 20 parts of isophorone diisocyanate and 10 parts of dicyclohexylmethane diisocyanate were added to a reaction kettle, the kettle temperature was maintained at 30±5°C, 30 parts of modified polyester polyol were added, and the reaction was carried out at 80°C for 3 hours, and then 40 parts of C-MDI were added, and the reaction was carried out at 80°C for 2 hours, and the temperature was cooled to room temperature to obtain component A. The test NCO% was 19.9%.

[0105] (II) Preparation of component B:

[0106] (21) Preparing a modified polyester polyol, comprising:

[0107] (211) Prepare: 0.8 mol of ethylene glycol, 0.6 mol of 1,4-butanediol, 0.1 mol of glycerol, 0.5 mol of terephthalic acid, and 0.5 mol of 1,4-butanediol;

[0108] (212) Preparation of modified polyester: The preparation method can refer to the steps of preparing the modified polyester polyol of component A in Example 1. The hydroxyl value of the prepared modified polyester polyol is 200 and the acid value is 2.2.

[0109] (22) Synthesis of component B:

[0110] Add 50 parts of modified polyester polyol and 40 parts of castor oil derivative polyol into the reactor, maintain the reactor temperature at 50±5°C, add 10 parts of polyoxypropylene triol (molecular weight 375), start stirring, raise the reactor temperature to 70±5°C, react for 3 hours, and cool to room temperature to obtain component B.

[0111] (23) Component A and component B are prepared according to the functional group molar ratio of -NCO: -OH = 1.6: 1.0 to form the adhesive. The adhesive is used to compound VMPET / PE and cured at 40°C. The VMPET / PE layer of the composite film is peeled off at different time periods, and the peel strength is tested after overlapping. The time taken to have no peel strength is recorded as the drying time. The peel strength of the composite film after full curing is tested.

[0112] Comparative Example 1

[0113] The difference from Example 1 is that in the modified polyester polyol used in component B, the monomer ratio is 0.9 mol of ethylene glycol, 0.4 mol of 1,4-butanediol, 0.1 mol of trimethylolpropane, 0.3 mol of 1,6-adipic acid, and 0.7 mol of 1,4-succinic acid.

[0114] Comparative Example 2

[0115] The difference from Example 2 is that the components of component B are 30 parts of modified polyester polyol, 30 parts of castor oil derivative polyol and 40 parts of polyoxypropylene glycol (molecular weight 400).

[0116] It can be known that the above comparative examples are not prior art, but comparative examples designed to compare the performance of the products of the present invention.

[0117] Table 1 shows the peel strength and drying time of solvent-free polyurethane adhesive

[0118] Peel strength (N / 15mm) Drying time (h) Example 1 5.97 5.5 Example 2 6.01 5.5 Example 3 5.86 5 Comparative Example 1 2.81 16 Comparative Example 2 3.04 12

[0119] It can be seen from the above comparison that the adhesive of the present invention is superior to the adhesive of the comparative example in terms of both peel stress and drying time.

[0120] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A high barrier fast solid solvent-free polyurethane adhesive, characterized in that: include: Component A and component B, wherein the component A and component B are used in combination according to a functional group molar ratio of -NCO:-OH=1.1-1.9:1, wherein the component A is a modified isocyanate adduct formed by the reaction of a modified polyester polyol and a polyisocyanate, and the NCO% mass percentage of the component A is 15%-27%; The B component is a mixture of castor oil derivative polyol, modified polyester polyol and polyether polyol.

2. The high barrier fast solid solvent-free polyurethane adhesive according to claim 1, characterized in that: In the components A and B, the modified polyester polyol is a polyester polyol with a functionality of two or more, which is prepared by an esterification condensation reaction of a small molecule polyol and a small molecule polyacid.

3. The high barrier fast solid solvent-free polyurethane adhesive according to claim 2, characterized in that: In the component A, the small molecule polyol in the polyester polyol with a functionality of two or more is at least one of ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, dipropylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,5-pentanediol, 1,4-cyclohexanediol and glycerol; In the component A, the small molecule polyacid in the polyester polyol with difunctionality or above is at least one of isophthalic acid, phthalic acid, terephthalic acid, 1,4-succinic acid, 1,6-hexanedioic acid, sebacic acid, azelaic acid and lauric acid.

4. The high-barrier, fast-curing, solvent-free polyurethane adhesive according to claim 3, characterized in that: Among the polyester polyols with a functionality of two or more in the A component, the small molecule polyols with a functionality of two or more are selected from the group consisting of ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, dipropylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, and 2,2-dimethyl-1,3-propylene glycol, and the amount used accounts for 50% to 100% of the total molar amount of the small molecule polyols.

5. The high barrier fast solid solvent-free polyurethane adhesive according to claim 2, characterized in that: In the B component, the small molecule polyol in the polyester polyol with a functionality of two or more is at least one of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,6-hexanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, glycerol, and trimethylolpropane; In the component B, the small molecular weight polyacid in the polyester polyol with a functionality of two or more is at least one of phthalic acid, terephthalic acid, 1,4-succinic acid, 1,6-hexanedioic acid, sebacic acid, azelaic acid and lauric acid.

6. The high-barrier, fast-curing, solvent-free polyurethane adhesive according to claim 5, characterized in that: Among the polyester polyols with a functionality of two or more in the B component, the small molecule polyols with a functionality of two or more are selected from the group consisting of ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 2,2-dimethyl-1,3-propylene glycol, 1,6-hexanediol, and 1,4-butanediol, and the amount used accounts for 50% to 100% of the total molar amount of the small molecule polyols.

7. The high barrier, fast-curing, solvent-free polyurethane adhesive according to any one of claims 2 to 6, characterized in that: In the A component and the B component, the small molecular weight polyacid in the polyester polyol with a functionality of two or more contains phenylcyclic acid which accounts for 20% to 50% of the total molar amount of the small molecular weight polyacid.

8. The high barrier, fast-curing, solvent-free polyurethane adhesive according to any one of claims 1 to 6, characterized in that: In the B component, each component is calculated by weight: 20-50 parts of castor oil derivative polyol; 20-50 parts of modified polyester polyol; 10-20 parts of polyether polyol.

9. The high barrier, fast solidifying, solvent-free polyurethane adhesive according to any one of claims 1 to 6, characterized in that: In the component A, the polyisocyanate is at least one of a mixture of diphenylmethane 4,4'-diisocyanate and diphenylmethane 2,4'-diisocyanate, toluene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane diisocyanate; In the B component, the polyether polyol is one or a mixture of more than one of polyoxypropylene diol, polyoxypropylene triol, polytetrahydrofuran diol, and polyoxypropylene-ethylene oxide diol.

10. A method for preparing the high-barrier, fast-curing, solvent-free polyurethane adhesive according to any one of claims 1 to 9, characterized in that: The following steps are involved: Prepare component A and component B respectively; Preparation of component A: First, the modified polyester polyol used in component A is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction; Add polyisocyanate to the reaction kettle, keep the kettle temperature at 25-35°C, then add the modified polyester polyol used in component A, react at 70-80°C for 3-4 hours, then add polyisocyanate and react at 70°C for 2 hours, and cool to room temperature after the reaction to obtain component A; Preparation of component B: First, the modified polyester polyol used in component B is prepared: a small molecule polyol and a small molecule polyacid are subjected to an esterification condensation reaction at a functional group molar ratio of -OH:-COOH=1.1-1.9:1, and the modified polyester polyol is obtained after the reaction; Add castor oil derivative polyol and the modified polyester polyol used for component B into the reaction kettle, keep the kettle temperature at 45-55°C, then add polyether polyol, start stirring, raise the kettle temperature to 65-75°C and react for 2-3 hours, and then cool to room temperature after the reaction to obtain component B; The prepared component A and component B are used in combination according to the functional group molar ratio of -NCO:-OH=1.1-1.9:1 to prepare a high-barrier, fast-curing, solvent-free polyurethane adhesive.