Partially-closed solvent-free polyurethane adhesive as well as preparation method and application thereof

Abstract

The invention provides a partially-closed solvent-free polyurethane adhesive as well as a preparation method and application thereof. The partially-closed solvent-free polyurethane adhesive is prepared from the following raw materials: a sealing agent terminated aromatic polyurethane prepolymer, an isocyanate terminated aliphatic polyurethane prepolymer and an amine curing agent, through the matching of the sealing agent terminated aromatic polyurethane prepolymer, the isocyanate terminated aliphatic polyurethane prepolymer and the amine curing agent, the obtained partially-sealed solvent-free polyurethane adhesive is safe and environment-friendly, has long opening time after being prepared, also has excellent hydrolysis resistance and heat resistance, and can be widely applied to the field of adhesive materials. The anti-yellowing grade is high; and the stripping force is high.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane, and in particular relates to a partially closed solvent-free polyurethane adhesive and a preparation method and application thereof. Background Art

[0002] Polyurethane adhesives can be divided into four types: solvent-based, high solid content, water-based and solvent-free. They are obtained by reacting polyols, chain extenders and isocyanates to obtain substances with block structures. As market demand increases, solvent-based adhesives are gradually replaced by environmentally friendly products. Among them, high solid content adhesives contain a small amount of solvent and cannot achieve true environmental protection. Water-based adhesives have poor weather resistance, and the solvent-free process is more complicated and requires professional equipment, resulting in high production costs. The processing is difficult and the differences between resin batches lead to unstable production.

[0003] For example, CN108467470A discloses a DMF-free composite closed high-solid polyurethane adhesive layer resin for synthetic leather to solve the problem of excessive DMF residue in the product when using traditional solvent-based polyurethane adhesive layer resin for bonding. However, this method also uses solvents, so it is not environmentally friendly.

[0004] For example, CN105419714A discloses an epoxy resin two-component polyurethane adhesive and a preparation method thereof. By introducing an epoxy resin complex, the adhesive forms an interpenetrating network polymer structure, thereby improving the shortcomings of two-component, solvent-free polyurethane adhesives, such as poor hydrolysis resistance and bubble generation during the curing process. And for example, CN104017532A discloses a high-strength solvent-free polyurethane adhesive and a preparation method thereof. When component A is not in contact with component B, component A has an open time of 12 to 15 hours. When combined with a deionized aqueous solution of component B, the pressing time is shortened to 15 to 25 seconds at a temperature of 130 to 140°C, and continuous operation can be achieved. The reaction time can be shortened or extended by increasing or decreasing the amount of component B. However, the two-component polyurethane adhesives provided by the above two inventions are affected by air humidity, and there are production control problems such as increased viscosity after mixing, resulting in uneven coating or even inability to coat. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a partially closed solvent-free polyurethane adhesive and a preparation method and application thereof. The partially closed solvent-free polyurethane adhesive is not only safe and environmentally friendly, but also has a long open time after compounding, and at the same time has excellent hydrolysis resistance, high yellowing resistance grade, high tensile strength, excellent heat resistance and excellent adhesion.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a partially blocked solvent-free polyurethane adhesive, wherein the raw materials of the partially blocked solvent-free polyurethane adhesive include a blocking agent-terminated aromatic polyurethane prepolymer, an isocyanate-terminated aliphatic polyurethane prepolymer and an amine curing agent.

[0008] In the present invention, the raw materials of the partially blocked solvent-free polyurethane adhesive include a blocking agent-terminated aromatic polyurethane prepolymer, an isocyanate-terminated aliphatic polyurethane prepolymer and an amine curing agent; wherein, there is a difference in isocyanate group activity between the isocyanate-terminated aliphatic polyurethane prepolymer and the blocking agent-terminated aromatic polyurethane prepolymer, the blocking agent-terminated aromatic polyurethane prepolymer needs to be unblocked at high temperature and then react with the amine curing agent, while the isocyanate-terminated aliphatic polyurethane prepolymer does not need a blocking and unblocking process and can directly react with the amine curing agent at high temperature for curing, so that the two can be compounded and mixed to achieve gradient temperature curing, so that the obtained polyurethane adhesive presents the viscosity of the adhesive in the rubber state stage during the liquid curing film-forming process, which is not only safe and environmentally friendly, but also has a long open time after compounding; in addition, the hydrogen bonding force provided by the blocking agent-terminated aromatic polyurethane prepolymer can also improve the strength, temperature resistance and high bonding performance of the polyurethane adhesive, and the isocyanate-terminated aliphatic polyurethane prepolymer can also improve the yellowing resistance of the polyurethane adhesive.

[0009] In summary, the partially closed solvent-free polyurethane adhesive provided by the present invention is not only safe and environmentally friendly, but also has a long open time after compounding, and has excellent hydrolysis resistance, high yellowing resistance grade, high tensile strength, excellent heat resistance and excellent adhesion.

[0010] Preferably, the raw materials of the partially closed solvent-free polyurethane adhesive include the following components in parts by weight:

[0011] 100 parts by weight of sealing agent-terminated aromatic polyurethane prepolymer;

[0012] 15 to 30 parts by weight of isocyanate-terminated aliphatic polyurethane prepolymer;

[0013] 9 to 15 parts by weight of amine curing agent.

[0014] Wherein, the amount of the isocyanate-terminated aliphatic polyurethane prepolymer can be 15 parts by weight, 17 parts by weight, 19 parts by weight, 21 parts by weight, 23 parts by weight, 25 parts by weight, 27 parts by weight, 29 parts by weight or 30 parts by weight, etc.

[0015] The amount of the amine curing agent can be 9 parts by weight, 10 parts by weight, 12 parts by weight, 14 parts by weight or 15 parts by weight.

[0016] Preferably, the raw materials of the isocyanate-terminated aliphatic polyurethane prepolymer include the following components in parts by weight:

[0017] Polyol A 70-90 parts by weight;

[0018] Isocyanate A 10-25 parts by weight;

[0019] Catalyst 0.001~0.01 parts by weight.

[0020] Wherein, the amount of the polyol A can be 70 parts by weight, 72 parts by weight, 74 parts by weight, 76 parts by weight, 78 parts by weight, 80 parts by weight, 82 parts by weight, 84 parts by weight, 86 parts by weight, 88 parts by weight or 90 parts by weight, etc.

[0021] The amount of isocyanate A can be 10 parts by weight, 12 parts by weight, 14 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 22 parts by weight, 24 parts by weight or 25 parts by weight.

[0022] The amount of the catalyst used can be 0.001 parts by weight, 0.003 parts by weight, 0.005 parts by weight, 0.007 parts by weight, 0.009 parts by weight or 0.01 parts by weight, etc.

[0023] Preferably, the polyol A comprises polyester polyol and / or polyether polyol.

[0024] Preferably, the polyester polyol includes any one or a combination of at least two of polyneopentyl adipate diol, poly1,4-butylene adipate diol, poly1,6-hexanediol adipate diol, polyethylene adipate diol, polymethylpropylene adipate diol, polydiethylene adipate diol or polymethylpropylene adipate diol.

[0025] Preferably, the polyether polyol includes any one or a combination of at least two of polyoxypropylene glycol, trifunctional polyoxypropylene glycol using trimethylolpropane or glycerol as an initiator, polyoxyethylene glycol or polytetramethylene ether glycol.

[0026] For example, the polyol A is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 2000, and polyoxypropylene glycol with a number average molecular weight of 1000, and the mass ratio of the three is 6:2:0.5; or, the polyol A is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 8000, and polyneopentyl adipate glycol with a number average molecular weight of 2000, and the mass ratio of the three is 6:2:0.5. The mass ratio of the polyols A is 4:4:1; or, the polyol A is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polymethyl propane adipate glycol with a number average molecular weight of 2000, and polyneopentyl adipate glycol with a number average molecular weight of 4000, and the mass ratio of the three is 10:3:4; or, the polyol A is polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 2000, and polyneopentyl adipate glycol with a number average molecular weight of 2000. The mass ratio of the three is 1:3:3; or, the polyol A is a combination of polyoxypropylene diol with a number average molecular weight of 2000, polyoxypropylene triol with a number average molecular weight of 2000, and polyadipate neopentyl glycol ester diol with a number average molecular weight of 2000, and the mass ratio of the three is 4:8:1; or, the polyol A is a combination of polyoxypropylene diol with a number average molecular weight of 2000, polyoxypropylene triol with a number average molecular weight of 6000, polyadipate neopentyl glycol ester diol with a number average molecular weight of 2000 A combination of glycol, ester and diol, the mass ratio of the three is 4:8:1; or, the polyol A is a combination of polyoxypropylene triol with a number average molecular weight of 3000, polyoxypropylene diol with a number average molecular weight of 2000, and polyoxypropylene diol with a number average molecular weight of 4000, and the mass ratio of the three is 8:4:3; or, the polyol A is a combination of polyoxypropylene diol with a number average molecular weight of 4000 and polyoxypropylene diol with a number average molecular weight of 1000, and the mass ratio of the two is 14:1.

[0027] Preferably, the number average molecular weight of the polyol A is 1000-10000, for example, 1000, 2000, 4000, 6000, 8000 or 10000.

[0028] Preferably, the isocyanate A comprises any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate or 4,4'-dicyclohexylmethane diisocyanate; typical but non-limiting combinations include: a combination of isophorone diisocyanate and hexamethylene diisocyanate, a combination of hexamethylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate, a combination of isophorone diisocyanate, hexamethylene diisocyanate and 4,4'-dicyclohexylmethane diisocyanate, and the like.

[0029] Preferably, the catalyst is a temperature-sensitive catalyst, for example, BiCAT 2536 from Leading Chemicals of the United States may be selected.

[0030] Preferably, the isocyanate-terminated aliphatic polyurethane prepolymer is obtained by subjecting polyol A and isocyanate A to a first reaction, and then adding a catalyst to conduct a second reaction.

[0031] Preferably, the temperature of the first reaction is 85-95°C, for example, 85°C, 87°C, 89°C, 91°C, 93°C or 95°C.

[0032] Preferably, the first reaction time is 1 to 3 h, for example, 1 h, 1.3 h, 1.6 h, 1.9 h, 2.1 h, 2.3 h, 2.5 h, 2.8 h or 3 h.

[0033] Preferably, after the first reaction is completed, the step of cooling the temperature to 55-65°C (eg, 55°C, 58°C, 60°C, 63°C or 65°C, etc.) is also included.

[0034] Preferably, the second reaction comprises the steps of first reacting at 70-80°C (e.g., 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, etc.) for 1-3h (e.g., 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h or 3h, etc.), and then reacting at 80-95°C (e.g., 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C or 95°C, etc.) for 2-5h (e.g., 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc.).

[0035] Preferably, the raw materials of the blocking agent-terminated aromatic polyurethane prepolymer include the following components in parts by weight:

[0036]

[0037] Wherein, the amount of the polyol B can be 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 80 parts by weight or 90 parts by weight, etc.

[0038] The amount of the isocyanate B can be 5 parts by weight, 7 parts by weight, 9 parts by weight, 11 parts by weight, 13 parts by weight, 15 parts by weight, 17 parts by weight, 19 parts by weight, 21 parts by weight or 22 parts by weight.

[0039] The acidic chain extender can be used in an amount of 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight or 5 parts by weight.

[0040] The amount of the stabilizer can be 0.02 parts by weight, 0.04 parts by weight, 0.06 parts by weight, 0.08 parts by weight or 0.1 parts by weight, etc.

[0041] The amount of the water absorbing agent can be 0.1 parts by weight, 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, 0.8 parts by weight or 1 part by weight.

[0042] The amount of the sealing agent can be 1 part by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, 9 parts by weight, 11 parts by weight, 13 parts by weight or 15 parts by weight.

[0043] Preferably, in the raw material of the blocking agent-terminated aromatic polyurethane prepolymer, the molar ratio of isocyanate group to hydroxyl group is (1.2-2):1, for example, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2:1; the regularity of the obtained polyurethane structure is further ensured by adjusting the molar ratio of isocyanate group to hydroxyl group (R value).

[0044] Preferably, the polyol B comprises polyester polyol and / or polyether polyol.

[0045] Preferably, the polyester polyol includes any one or a combination of at least two of polyneopentyl adipate diol, poly1,4-butylene adipate diol, poly1,6-hexanediol adipate diol, polyethylene adipate diol, polymethylpropylene adipate diol, polydiethylene adipate diol or polymethylpropylene adipate diol.

[0046] Preferably, the polyether polyol includes any one or a combination of at least two of polyoxypropylene glycol, trifunctional polyoxypropylene glycol using trimethylolpropane or glycerol as an initiator, polyoxyethylene glycol or polytetramethylene ether glycol.

[0047] For example, the polyol B is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 2000, and polyoxypropylene glycol with a number average molecular weight of 1000, and the mass ratio of the three is 6:2:0.5; or, the polyol B is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 8000, and polyneopentyl adipate glycol with a number average molecular weight of 2000, and the mass ratio of the three is 6:2:0.5. The mass ratio of the polyol B is 4:4:1; or, the polyol B is a combination of polyoxypropylene glycol with a number average molecular weight of 4000, polymethyl propane adipate glycol with a number average molecular weight of 2000, and polyneopentyl adipate glycol with a number average molecular weight of 4000, and the mass ratio of the three is 10:3:4; or, the polyol B is polyoxypropylene glycol with a number average molecular weight of 4000, polyoxypropylene glycol with a number average molecular weight of 2000, and polyneopentyl adipate glycol with a number average molecular weight of 2000. The mass ratio of the three is 1:3:3; or, the polyol B is a combination of polyoxypropylene diol with a number average molecular weight of 2000, polyoxypropylene triol with a number average molecular weight of 2000, and polyadipate neopentyl glycol ester diol with a number average molecular weight of 2000, and the mass ratio of the three is 4:8:1; or, the polyol B is a combination of polyoxypropylene diol with a number average molecular weight of 2000, polyoxypropylene triol with a number average molecular weight of 6000, polyadipate neopentyl glycol ester diol with a number average molecular weight of 2000 A combination of glycol, ester and glycol, the mass ratio of the three is 4:8:1; or, the polyol B is a combination of polyoxypropylene triol with a number average molecular weight of 3000, polyoxypropylene diol with a number average molecular weight of 2000, and polyoxypropylene diol with a number average molecular weight of 4000, and the mass ratio of the three is 8:4:3; or, the polyol B is a combination of polyoxypropylene diol with a number average molecular weight of 4000 and polyoxypropylene diol with a number average molecular weight of 1000, and the mass ratio of the two is 14:1.

[0048] Preferably, the number average molecular weight of the polyol B is 1000-10000, for example, 1000, 2000, 4000, 6000, 8000 or 10000.

[0049] Preferably, the isocyanate B includes toluene diisocyanate.

[0050] Preferably, the acidic chain extender comprises dimethylolpropionic acid.

[0051] In the preferred technical scheme of the present invention, dimethylolpropionic acid is used as an acidic chain extender, which can effectively make the resin system weakly acidic, reduce the chromaticity of the resin and improve the storage stability of the resin, and can react and cross-link with an amine curing agent during high-temperature curing, further improving the hydrolysis resistance and temperature resistance of the polyurethane adhesive, and can also slowly react with excess amine curing agent during storage after curing, so that the yellowing resistance of the polyurethane adhesive is further improved.

[0052] Preferably, the stabilizer comprises benzoyl chloride.

[0053] Preferably, the water absorbent comprises p-toluenesulfonyl isocyanate.

[0054] Preferably, the blocking agent includes any one of oxime compounds, acetanilide or pyrazole compounds or a combination of at least two thereof, and is more preferably butanone oxime.

[0055] Preferably, the raw material of the blocking agent-terminated aromatic polyurethane prepolymer further includes a cross-linking agent.

[0056] Preferably, the content of the crosslinking agent in the raw material of the blocker-terminated aromatic polyurethane prepolymer is 0 to 5 parts by weight and is not 0, for example, 0.1 parts by weight, 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight or 5 parts by weight.

[0057] Preferably, the cross-linking agent comprises trimethylolpropane and / or glycerol.

[0058] Preferably, the blocking agent-terminated aromatic polyurethane prepolymer is prepared by the following method, which comprises: firstly mixing a stabilizer, a polyol B and an optional cross-linking agent, adding isocyanate B for a first reaction, then adding an acidic chain extender for a second reaction, and finally adding a blocking agent and a water absorbent for a blocking reaction until the isocyanate group of the system is 0, thereby obtaining the blocking agent-terminated aromatic polyurethane prepolymer.

[0059] Preferably, the temperature of the first reaction is 65-75°C, for example, 65°C, 67°C, 69°C, 71°C, 73°C or 75°C.

[0060] Preferably, the first reaction time is 1 to 3 h, such as 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0061] Preferably, after the first reaction, the temperature is further reduced to 45-55° C. (eg, 45° C., 47° C., 49° C., 51° C., 53° C. or 55° C., etc.).

[0062] Preferably, the temperature of the second reaction is 70-80°C, for example, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C.

[0063] Preferably, the second reaction time is 1 to 3 h, such as 1 h, 1.5 h, 2 h, 2.5 h or 3 h.

[0064] Preferably, after the second reaction is completed, the mass percentage of isocyanate groups in the system is ≤4.12%.

[0065] Preferably, the temperature of the blocking reaction is 60-80°C, for example, 60°C, 62°C, 64°C, 66°C, 68°C, 70°C, 72°C, 74°C, 76°C, 78°C or 80°C.

[0066] Preferably, the blocking reaction time is 1 to 2 h, for example, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h or 2 h.

[0067] Preferably, the amine curing agent includes any one of 3,3-diethyl-4,4-diaminodiphenylmethane (MOEA), 4,4-diaminodiphenylmethane (MDA) or adipic acid dihydrazide (ADH), or a combination of at least two thereof.

[0068] Preferably, the raw materials of the partially closed solvent-free polyurethane adhesive also include a leveling agent.

[0069] In a second aspect, the present invention provides a method for preparing the partially blocked solvent-free polyurethane adhesive as described in the first aspect, the preparation method comprising: mixing a blocking agent-terminated aromatic polyurethane prepolymer, an isocyanate-terminated aliphatic polyurethane prepolymer, an amine curing agent and optionally a leveling agent to obtain the partially blocked solvent-free polyurethane adhesive.

[0070] Preferably, the preparation method comprises: firstly mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer, and then adding an amine curing agent and optionally a leveling agent and mixing them to obtain the partially blocked solvent-free polyurethane adhesive.

[0071] In a third aspect, the present invention provides a polyurethane material, which is obtained by curing the partially closed solvent-free polyurethane adhesive as described in the first aspect.

[0072] Preferably, the curing temperature is 120-160°C, for example, 120°C, 130°C, 140°C, 150°C or 160°C.

[0073] Preferably, the curing time is 4 to 10 minutes, for example, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes.

[0074] In a fourth aspect, the present invention provides a leather comprising the polyurethane material as described in the third aspect.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] (1) The partially enclosed solvent-free polyurethane adhesive provided by the present invention is environmentally friendly and pollution-free, and has a long open time after compounding, and can be sealed and stably stored for more than 7 days;

[0077] (2) The partially closed solvent-free polyurethane adhesive provided by the present invention can realize the function of an adhesive by heating and baking, and has excellent hydrolysis resistance, high yellowing resistance, high heat resistance and high peeling force; wherein, the initial peeling force is above 8.5kg / 3cm, the peeling force retention rate after being placed in an environment of 70°C and 95% for 5 weeks is above 88%, the leather surface texture retention time at 120°C is above 21 days, and the yellowing resistance grade reaches level 4.0. DETAILED DESCRIPTION

[0078] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0079] The detailed information of some raw materials used in the following specific embodiments is shown in Table 1:

[0080] Table 1

[0081]

[0082] Example 1

[0083] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0084]

[0085]

[0086] The preparation method of the isocyanate-terminated aliphatic polyurethane prepolymer comprises: mixing 83.7 parts by weight of polyoxypropylene triol B, 7 parts by weight of isophorone diisocyanate and 9.3 parts by weight of hexamethylene diisocyanate and stirring for 10 minutes, heating to 90° C. for reaction for 1 hour, then cooling to 60° C., adding 0.002 parts by weight of catalyst BiCAT 2536, slowly heating to 75° C. for reaction for 2 hours, then heating to 90° C. for insulation reaction for 3 hours, testing the NCO value of the system to be ≤3.51%, cooling to below 65° C. and discharging to obtain the isocyanate-terminated polyurethane prepolymer;

[0087] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 8.7 parts by weight of polyoxypropylene glycol A, 8.7 parts by weight of polyoxypropylene adipate neopentyl glycol ester diol and 43.3 parts by weight of polyoxypropylene triol B are mixed and stirred for 15 minutes, 12.5 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, and then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, and the NCO value of the test system is ≤4.12%, and then the temperature is lowered to below 65° C., 6.3 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, and the temperature is kept at 70° C. for 1 hour for sealing reaction until the NCO value of the system is 0, thereby obtaining the sealing agent-terminated aromatic polyurethane prepolymer;

[0088] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0089] Example 2

[0090] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0091]

[0092]

[0093] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0094] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 15.6 parts by weight of polyoxypropylene glycol C, 8.7 parts by weight of polyoxypropylene adipate neopentyl glycol ester diol and 39.1 parts by weight of polyoxypropylene triol A are mixed and stirred for 15 minutes, then 11.3 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, the NCO value of the test system is ≤3.68%, then the temperature is lowered to below 65° C., 5.6 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 70° C. for 1 hour for sealing reaction, until the NCO value of the system is 0, and the sealing agent-terminated aromatic polyurethane prepolymer is obtained;

[0095] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0096] Example 3

[0097] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0098]

[0099] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0100] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 9.1 parts by weight of polyoxypropylene glycol D, 9.1 parts by weight of polyoxypropylene adipate neopentyl glycol ester diol and 45.2 parts by weight of polyoxypropylene triol A are mixed and stirred for 15 minutes, then 10.7 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, and the NCO value of the test system is ≤3.48%, then the temperature is lowered to below 65° C., 5.4 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, and the temperature is kept at 70° C. for 1 hour for sealing reaction until the NCO value of the system is 0, thereby obtaining the sealing agent-terminated aromatic polyurethane prepolymer;

[0101] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0102] Example 4

[0103] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0104]

[0105] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0106] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 16.4 parts by weight of polyoxypropylene glycol C, 8.2 parts by weight of polyoxypropylene neopentyl glycol adipate diol and 41 parts by weight of polyoxypropylene triol B are mixed and stirred for 15 minutes, then 9.2 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, the NCO value of the test system is ≤2.95%, then the temperature is lowered to below 65° C., 4.6 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 70° C. for 1 hour for sealing reaction, until the NCO value of the system is 0, and the hydroxyl-terminated aromatic polyurethane prepolymer is obtained;

[0107] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0108] Example 5

[0109] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0110]

[0111] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0112] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 8.1 parts by weight of polyoxypropylene glycol A, 8.1 parts by weight of polyoxypropylene adipate neopentyl glycol ester diol and 48.4 parts by weight of polyoxypropylene triol B are mixed and stirred for 15 minutes, then 9.9 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 68° C. within 30 minutes, and then the temperature is kept to react for 1.5 hours, then the temperature is lowered to 55° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 75° C. and reacted for 1.5 hours, the NCO value of the test system is ≤3.2%, then the temperature is lowered to below 65° C., 5 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 75° C. for 1.5 hours for sealing reaction, until the NCO value of the system is 0, and the sealing agent-terminated aromatic polyurethane prepolymer is obtained;

[0113] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0114] Example 6

[0115] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0116]

[0117] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0118] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 7.8 parts by weight of polyoxypropylene glycol A, 7.8 parts by weight of polyadipate neopentyl glycol ester diol and 50.6 parts by weight of polyoxypropylene triol C are mixed and stirred for 15 minutes, then 8.9 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, the NCO value of the test system is ≤2.85%, then the temperature is lowered to below 65° C., 4.4 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 70° C. for 1 hour for sealing reaction, until the NCO value of the system is 0, and the sealing agent-terminated aromatic polyurethane prepolymer is obtained;

[0119] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0120] Example 7

[0121] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0122]

[0123] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0124] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 13.2 parts by weight of polyoxypropylene glycol C, 8.8 parts by weight of polyoxypropylene triol B are mixed and stirred for 15 minutes, then 9.1 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept for reaction for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. for reaction for 1 hour, and the NCO value of the test system is ≤2.91%, then the temperature is lowered to below 65° C., 4.5 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, and the temperature is kept at 70° C. for blocking reaction for 1 hour until the NCO value of the system is 0, thereby obtaining the sealing agent-terminated aromatic polyurethane prepolymer;

[0125] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0126] Example 8

[0127] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0128]

[0129]

[0130] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0131] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 9.6 parts by weight of polyoxypropylene glycol D, 9.6 parts by weight of polyoxypropylene adipate glycol, 9.6 parts by weight of polyoxypropylene triol A and 38.5 parts by weight of polyoxypropylene triol C are mixed and stirred for 15 minutes, then 8 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, the NCO value of the test system is ≤2.57%, then the temperature is lowered to below 65° C., 4 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 70° C. for 1 hour for sealing reaction, until the NCO value of the system is 0, and the sealing agent-terminated aromatic polyurethane prepolymer is obtained;

[0132] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0133] Example 9

[0134] A partially closed solvent-free polyurethane adhesive, the raw materials of which include the following components:

[0135]

[0136] Wherein, the isocyanate-terminated aliphatic polyurethane prepolymer is the same as that in Example 1;

[0137] The preparation method of the sealing agent-terminated aromatic polyurethane prepolymer comprises: firstly, 0.0001 parts by weight of stabilizer benzoyl chloride, 15 parts by weight of polyoxypropylene glycol D, 7.5 parts by weight of polyadipate neopentyl glycol ester diol and 45.1 parts by weight of polyoxypropylene triol B are mixed and stirred for 15 minutes, then 7.9 parts by weight of toluene diisocyanate are quickly added at one time, the temperature is raised to 70° C. within 30 minutes, and then the temperature is kept to react for 1 hour, then the temperature is lowered to 50° C., 0.2 parts by weight of dimethylol propionic acid is added, the temperature is slowly raised to 70° C. and reacted for 1 hour, the NCO value of the test system is ≤2.52%, then the temperature is lowered to below 65° C., 4 parts by weight of butanone oxime and 0.4 parts by weight of p-toluenesulfonyl isocyanate are added, the temperature is kept at 70° C. for 1 hour for sealing reaction, until the NCO value of the system is 0, and the sealing agent-terminated aromatic polyurethane prepolymer is obtained;

[0138] The preparation method of the partially blocked solvent-free polyurethane adhesive provided in this embodiment includes: stirring and mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer for 0.5 h, then adding 3,3-diethyl-4,4-diaminodiphenylmethane and a leveling agent BYK-333, and dispersing at 300 rpm for 10 min to obtain the partially blocked solvent-free polyurethane adhesive.

[0139] Example 10

[0140] A partially closed solvent-free polyurethane adhesive is different from Example 1 only in that the amount of 3,3-diethyl-4,4-diaminodiphenylmethane is 8 parts by weight, and other substances, amounts and preparation methods are the same as those in Example 1.

[0141] Embodiment 11

[0142] A partially closed solvent-free polyurethane adhesive is different from Example 1 only in that the amount of 3,3-diethyl-4,4-diaminodiphenylmethane is 16 parts by weight, and other substances, amounts and preparation methods are the same as those in Example 1.

[0143] Embodiments 12 to 13

[0144] A partially closed solvent-free polyurethane adhesive is different from Example 1 only in that the amounts of isocyanate-terminated aliphatic polyurethane prepolymer are 10 parts by weight (Example 12) and 40 parts by weight (Example 13), respectively, and other substances, amounts and preparation methods are the same as those in Example 1.

[0145] Comparative Example 1

[0146] A partially closed solvent-free polyurethane adhesive, which differs from Example 1 only in that 12.6 parts by weight of 3,3-dimethyl-4,4-diaminodicyclohexylmethane is used to replace 13.5 parts by weight of 3,3-diethyl-4,4-diaminodiphenylmethane, and other substances, amounts and preparation methods are the same as those in Example 1.

[0147] Comparative Example 2

[0148] A partially closed solvent-free polyurethane adhesive is disclosed. The difference between the adhesive and Example 1 is that an equimolar amount of 1,4-butanediol is used to replace dimethylolpropionic acid, and other substances, amounts and preparation methods are the same as those in Example 1.

[0149] Comparative Example 3

[0150] A partially closed solvent-free polyurethane adhesive is different from Example 1 in that no isocyanate-terminated aliphatic polyurethane prepolymer is added, and the amount of 3,3-diethyl-4,4-diaminodiphenylmethane is 11.4 parts by weight, and other substances, amounts and preparation methods are the same as those in Example 1.

[0151] Comparative Example 4

[0152] A partially closed solvent-free polyurethane adhesive is disclosed, which differs from Example 1 in that no isocyanate-terminated aliphatic polyurethane prepolymer is added, and 10.7 parts by weight of 3,3-dimethyl-4,4-diaminodicyclohexylmethane is used to replace 13.5 parts by weight of 3,3-diethyl-4,4-diaminodiphenylmethane, and other substances, amounts used and preparation methods are the same as those in Example 1.

[0153] Comparative Example 5

[0154] A partially blocked solvent-free polyurethane adhesive, which differs from Example 1 in that the NCO group of the isocyanate-terminated aliphatic polyurethane resin is blocked with butanone oxime and then mixed with a blocking agent-terminated aromatic polyurethane prepolymer, and other substances, amounts and preparation methods are the same as those in Example 1;

[0155] The method for sealing the NCO group of the isocyanate-terminated aliphatic polyurethane resin with butanone oxime comprises: mixing 83.7 parts by weight of polyoxypropylene triol B, 7 parts by weight of isophorone diisocyanate and 9.3 parts by weight of hexamethylene diisocyanate and stirring for 10 minutes, heating to 90° C. for reaction for 1 hour, then cooling to 60° C., adding 0.002 parts by weight of catalyst BiCAT 2536, slowly heating to 75° C. for reaction for 2 hours, heating to 90° C. for insulation for reaction for 3 hours, and the NCO value of the test system is ≤3.51%, cooling to below 65° C., adding 45.5 parts by weight of butanone oxime and insulation at 70° C. for 30 minutes, and the NCO value of the test system is zero, that is, the butanone oxime-blocked aliphatic polyurethane resin is obtained.

[0156] Comparative Example 6

[0157] A partially closed solvent-free polyurethane adhesive, which differs from Example 1 in that 3,3-diethyl-4,4-diaminodiphenylmethane is not added, and other substances, amounts and preparation methods are the same as those in Example 1.

[0158] Comparative Example 7

[0159] A partially closed solvent-free polyurethane adhesive is different from Example 1 in that equimolar toluene diisocyanate is used to replace isophorone diisocyanate and hexamethylene diisocyanate, and other substances, amounts and preparation methods are the same as those in Example 1.

[0160] Comparative Example 8

[0161] A partially closed solvent-free polyurethane adhesive is different from Example 1 in that isophorone diisocyanate is used in an equimolar amount to replace toluene diisocyanate, and other substances, amounts and preparation methods are the same as those in Example 1.

[0162] Performance Test:

[0163] (1) Open time after mixing: The time when the partially enclosed solvent-free polyurethane adhesive has fluidity and can continue to be used is recorded. It is usually based on the viscosity after placement not exceeding twice the initial viscosity.

[0164] (2) Peel force: A partially enclosed solvent-free polyurethane adhesive was scraped onto the JF-PDY-851MY surface film (see fabric ingredients below) using a 300 μm coating rod, and the film was made sticky after being baked at 120°C for 3 min. The film was laminated with a cotton-like lint base fabric and then pressed with a 10 kg roller. The film was baked at 150°C for 5 min until fully cured. The peel force of the cured film was tested according to QB / T2888-2007 standard, and then the film was placed at 70°C and 95% for 5 weeks before being tested again for peel force. The peel force retention rate was calculated as (peel force after 5 weeks / initial peel force)×100%.

[0165] Among them, the ingredients of the JF-PDY-851MY surface film are: 100 parts by weight of Huafeng JF-PDY-851MY resin, 1 part by weight of TEGO 270 wetting and leveling agent (purchased from Evonik Specialty Chemicals (Shanghai) Co., Ltd.), 2 parts by weight of dark blue water-based black slurry BLPE 517 (purchased from Zhejiang Deep Blue New Materials Technology Co., Ltd.) and 0.8 parts by weight of TEGO ViscoPlus 3030 thickener (purchased from Evonik Specialty Chemicals (Shanghai) Co., Ltd.); the above raw materials are dispersed for 30 minutes, filtered and degassed for 30 minutes, and then coated on release paper (purchased from Huafeng, type 301) for 10 seconds, baked at 90°C, 110°C and 130°C for 3 minutes respectively, then coated twice for 15 seconds, and baked at 90°C, 110°C and 130°C for 3 minutes respectively, to obtain the JF-PDY-851MY surface film.

[0166] (3) 120℃ leather surface grain retention time: The sample preparation method is consistent with the peel strength test method. The leather sample is cut into two parts, one of which is used for comparison and observation, and the other is placed in a 120℃ oven to observe whether the grain changes over time. The time point when the grain changes is recorded as the grain retention time.

[0167] (4) Yellowing resistance grade: Tested by two 15W UVB lamps for 4 hours, and compared with the test grade based on the color chart.

[0168] The polyurethane adhesives provided in Examples 1 to 13 and Comparative Examples 1 to 8 were tested using the above test method, and the test results are shown in Table 2;

[0169] Table 2

[0170]

[0171]

[0172] Note: “ / ” means that the test cannot be performed.

[0173] From the data in Table 2, we can see that:

[0174] (1) The partially enclosed solvent-free polyurethane adhesives provided in Examples 1 to 9 have a long open time after formulation and can be sealed and stably stored for more than 7 days. The initial peel force of the surface film is more than 8.5 kg / 3 cm, and the peel force retention rate after being placed in an environment of 70°C and 95% for 5 weeks is more than 88%. The leather surface texture is retained for more than 21 days at 120°C, and the yellowing resistance grade reaches 4.0.

[0175] (2) Compared with Example 1, the initial peel force, jungle 5 cycle retention rate, heat resistance and yellowing resistance of Examples 10 to 11 all showed a serious decline. This is because too much or too little curing agent leads to low crosslinking degree and low molecular weight after curing, which ultimately deteriorates the performance.

[0176] (3) Compared with Example 1, the initial peel force, jungle 5 cycle retention rate, heat resistance and yellowing resistance of Examples 12 to 13 all decreased to varying degrees. This is because excessive or insufficient addition of aliphatic polyurethane prepolymers resulted in excessive or insufficient addition of curing agent in the system, which ultimately resulted in low crosslinking degree and low molecular weight after curing, and ultimately poor performance.

[0177] (4) Compared with Example 1, the 3,3-dimethyl-4,4-diaminodicyclohexylmethane (DMDC) used in Comparative Example 1 reacted violently after mixing with the resin, resulting in an increase in viscosity and inability to complete the batching, and the physical properties could not be tested. The reason was that the aliphatic primary amine was too active and reacted violently with NCO instantly.

[0178] (5) Compared with Example 1, the chain extender 1,4-butanediol in Comparative Example 2 fails to provide an acidic carboxyl structure, and the yellowing resistance of the resin will be lower. At the same time, compared with the cross-linking reaction between the carboxyl group and the amino group, and because the cross-linking degree of the 1,4-butanediol structure is lower, the hydrolysis resistance retention rate will also decrease.

[0179] (6) Compared with Example 1, no isocyanate-terminated polyurethane prepolymer was added in Comparative Example 3, so that the yellowing resistance of the obtained polyurethane adhesive was poor. The reason is that the pure aromatic polyurethane resin is easily oxidized into color-developing yellowing groups.

[0180] (7) Compared with Example 1, in Comparative Example 4, except that the factors affecting the yellowing resistance are the same as those of Comparative Example 2, after 3,3-dimethyl-4,4-diaminodicyclohexylmethane replaces 3,3-diethyl-4,4-diaminodiphenylmethane, the amino group activity is high, the storage stability is poor, and it is easily oxidized to produce yellowing.

[0181] (8) Compared with Example 1, after the isocyanate-terminated polyurethane prepolymer in Comparative Example 5 was blocked with butanone oxime, the deblocking temperature was higher than 160°C, so the resin and curing agent were not fully cured after mixing, resulting in incomplete curing and low crosslinking degree, which ultimately made the heat resistance and yellowing resistance worse.

[0182] (9) Compared with Example 1, Comparative Example 6 did not add 3,3-diethyl-4,4-diaminodiphenylmethane and could not be cured, so the performance could not be tested.

[0183] (10) Compared with Example 1, the yellowing resistance of Comparative Example 7 is poor because toluene diisocyanate replaces aliphatic isocyanate. In addition, the isocyanate-terminated polyurethane prepolymer prepared by toluene diisocyanate has very poor storage stability due to its high activity.

[0184] (11) Compared with Example 1, in Comparative Example 8, after isophorone diisocyanate replaced toluene diisocyanate, the unblocking temperature after blocking with butanone oxime was higher than 160 degrees. Since 80% of the main resin could not participate in the curing reaction of the curing agent, the curing agent was seriously excessive, and it was impossible to cure, and the physical properties could not be tested. The applicant declares that the present invention illustrates a partially blocked solvent-free polyurethane adhesive and its preparation method and application through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of the raw materials of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A partially closed solvent-free polyurethane adhesive, characterized in that: The raw materials of the partially blocked solvent-free polyurethane adhesive include blocking agent-terminated aromatic polyurethane prepolymer, isocyanate-terminated aliphatic polyurethane prepolymer and amine curing agent.

2. The partially closed solvent-free polyurethane adhesive according to claim 1, characterized in that: The raw materials of the partially closed solvent-free polyurethane adhesive include the following components in parts by weight: 100 parts by weight of sealing agent-terminated aromatic polyurethane prepolymer; 15 to 30 parts by weight of isocyanate-terminated aliphatic polyurethane prepolymer; 9 to 15 parts by weight of amine curing agent.

3. The partially closed solvent-free polyurethane adhesive according to claim 1 or 2, characterized in that: The raw materials of the isocyanate-terminated aliphatic polyurethane prepolymer include the following components in parts by weight: Polyol A 70-90 parts by weight; Isocyanate A 10-25 parts by weight; Catalyst 0.001-0.01 parts by weight; Preferably, the polyol A comprises polyester polyol and / or polyether polyol; Preferably, the polyester polyol includes any one or a combination of at least two of polyneopentyl adipate diol, poly1,4-butylene adipate diol, poly1,6-hexane adipate diol, polyethylene adipate diol, polymethylpropylene adipate diol, polydiethylene adipate diol or polybutylene adipate methylpropylene glycol ester diol; Preferably, the polyether polyol comprises any one or a combination of at least two of polyoxypropylene glycol, trifunctional polyoxypropylene glycol using trimethylolpropane or glycerol as an initiator, polyoxyethylene glycol or polytetramethylene ether glycol; Preferably, the isocyanate A comprises any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate or 4,4'-dicyclohexylmethane diisocyanate; Preferably, the catalyst is a temperature-sensitive catalyst.

4. The partially closed solvent-free polyurethane adhesive according to claim 3, characterized in that: The isocyanate-terminated aliphatic polyurethane prepolymer is obtained by reacting polyol A and isocyanate A for the first time, and then adding a catalyst for the second reaction; Preferably, the temperature of the first reaction is 85-95°C and the time is 1-3h; Preferably, after the first reaction is completed, the step of cooling the temperature to 55-65° C. is also included; Preferably, the second reaction comprises the steps of first reacting at 70-80° C. for 1-3 h, and then reacting at 80-95° C. for 2-5 h.

5. The partially closed solvent-free polyurethane adhesive according to any one of claims 1 to 4, characterized in that: The raw materials of the blocking agent-terminated aromatic polyurethane prepolymer include the following components in parts by weight: Preferably, the polyol B comprises polyester polyol and / or polyether polyol; Preferably, the polyester polyol includes any one or a combination of at least two of polyneopentyl adipate diol, poly1,4-butylene adipate diol, poly1,6-hexane adipate diol, polyethylene adipate diol, polymethylpropylene adipate diol, polydiethylene adipate diol or polybutylene adipate methylpropylene glycol ester diol; Preferably, the polyether polyol comprises any one or a combination of at least two of polyoxypropylene glycol, trifunctional polyoxypropylene glycol using trimethylolpropane or glycerol as an initiator, polyoxyethylene glycol or polytetramethylene ether glycol; Preferably, the isocyanate B includes toluene diisocyanate; Preferably, the acidic chain extender comprises dimethylolpropionic acid; Preferably, the stabilizer comprises benzoyl chloride; Preferably, the water absorbing agent comprises p-toluenesulfonyl isocyanate; Preferably, the blocking agent comprises any one or a combination of at least two of oxime compounds, acetanilide or pyrazole compounds, and is more preferably butanone oxime; Preferably, the raw material of the blocking agent-terminated aromatic polyurethane prepolymer further includes a cross-linking agent; Preferably, the content of the crosslinking agent in the raw material of the blocking agent-terminated aromatic polyurethane prepolymer is 0 to 5 parts by weight and is not 0; Preferably, the cross-linking agent comprises trimethylolpropane and / or glycerol.

6. The partially closed solvent-free polyurethane adhesive according to claim 5, characterized in that: The blocking agent-terminated aromatic polyurethane prepolymer is prepared by the following method, which comprises: firstly mixing a stabilizer, a polyol B and an optional crosslinking agent, adding isocyanate B for a first reaction, then adding an acidic chain extender for a second reaction, and finally adding a blocking agent and a water absorbent for a blocking reaction until the isocyanate group of the system is 0, thereby obtaining the blocking agent-terminated aromatic polyurethane prepolymer; Preferably, the temperature of the first reaction is 65-75°C and the time is 1-3h; Preferably, after the first reaction, the temperature is further reduced to 45-55°C; Preferably, the temperature of the second reaction is 70-80°C and the time is 1-3h; Preferably, the blocking reaction is carried out at a temperature of 60 to 80° C. and for a time of 1 to 2 hours.

7. The partially closed solvent-free polyurethane adhesive according to any one of claims 1 to 6, characterized in that: The amine curing agent includes any one of 3,3-diethyl-4,4-diaminodiphenylmethane, 4,4-diaminodiphenylmethane or adipic acid dihydrazide or a combination of at least two thereof; Preferably, the raw materials of the partially closed solvent-free polyurethane adhesive also include a leveling agent.

8. A method for preparing a partially closed solvent-free polyurethane adhesive as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises: mixing a blocking agent-terminated aromatic polyurethane prepolymer, an isocyanate-terminated aliphatic polyurethane prepolymer, an amine curing agent and an optional leveling agent to obtain the partially blocked solvent-free polyurethane adhesive; Preferably, the preparation method comprises: firstly mixing a blocking agent-terminated aromatic polyurethane prepolymer and an isocyanate-terminated aliphatic polyurethane prepolymer, and then adding an amine curing agent and optionally a leveling agent and mixing them to obtain the partially blocked solvent-free polyurethane adhesive.

9. A polyurethane material, which is obtained by curing the partially closed solvent-free polyurethane adhesive according to any one of claims 1 to 7; Preferably, the curing temperature is 120-160° C. and the curing time is 4-10 minutes.

10. A leather, characterized in that: The leather comprises the polyurethane material as claimed in claim 9.

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