Multi-branched time-controllable curing waterborne polyurethane adhesive as well as preparation method and application thereof

Abstract

The invention discloses a multi-branched time-controllable curing waterborne polyurethane adhesive and application, and belongs to the technical field of high polymer materials. Comprising the following components: a polyhydroxy-containing aqueous multi-branched polyurethane dispersion A; a curing agent B containing a polyisocyanate; wherein the polyhydroxy-containing aqueous multi-branched polyurethane dispersion A is obtained by introducing a controllable number of OH functional groups into a molecular chain and / or a molecular chain end of linear polyurethane. The advantages of linear polyurethane and hyperbranched polyurethane are combined, a controllable number of OH functional groups are introduced into a molecular chain and / or a molecular chain end of traditional linear polyurethane, and the prepared multi-branched waterborne polyurethane dispersion and a curing agent containing polyisocyanate are mixed to obtain the adhesive, so that the adhesive has the advantages that the adhesive is uniform and uniform, and the adhesive has a good application prospect. The adhesive has the advantages of controllable curing, good film-forming property, high temperature resistance, chemical resistance and the like, and can be used for an artificial leather bonding layer.

Description

Technical Field

[0001] The present application relates to a multi-branched time-controlled curing water-based polyurethane adhesive and its application, belonging to the technical field of polymer materials. Background Art

[0002] Polyurethane is a widely used polymer material with advantages such as diverse product forms and strong molecular chain designability. In recent years, water-based polyurethane has become one of the products used in artificial leather adhesive layers due to its environmental protection and excellent performance. The patent with publication number CN102618204A provides a hot melt adhesive for artificial leather adhesive layers, and the preparation method is as follows: firstly reacting oligomer polyols and epoxy resins, aromatic polyhydroxy special polyethers and diisocyanates, then adding hydrophilic chain extenders and small molecule polyol chain extenders for chain extension reaction to obtain an intermediate product, neutralizing with organic amines and emulsifying with water to generate a polyurethane emulsion, and finally removing the organic solvent under reduced pressure to obtain an aqueous polyurethane emulsion, and then adding special organosilicon surfactants, ferric chloride aqueous solution, water-based curing agent, natural rubber, chloroprene rubber, nitrile rubber, thickener, and a hot melt adhesive for artificial leather adhesive layers are prepared. This adhesive needs to use aromatic polyhydroxy special polyether, and needs to be combined with a variety of additives to meet the performance requirements of the artificial leather adhesive layer; the patent with publication number CN102942664A provides a preparation method of terminal hydroxyl hyperbranched polyurethane: 1. Dissolve terminal hydroxyl small molecule polyol in a non-protonic organic solvent; 2. Heat diisocyanate to 70-90°C, add to 1, add catalyst, and react to obtain the first generation hyperbranched prepolymer a1; 3. Cool a1 and dialkanolamine to 0-15°C, keep warm and mix, then react, separate and purify the product with a precipitant, and vacuum dry to obtain the first generation terminal hydroxyl hyperbranched polyurethane A1. This patent uses dioxane Alcoholamine can introduce OH functional groups into the terminal groups of polyurethane prepolymers to form hyperbranched structures; the patent with publication number CN113150239A discloses a preparation method for medical polyurethane adhesive with controllable curing time, the steps of which include: 1. reacting diisocyanate and polyethylene glycol at a molar ratio of 2:1 to obtain an isocyanate-terminated precursor; 2. adding a certain amount of terminal hydroxyl chain extender to the precursor obtained in step 1 according to R value (-NCO / -OH) = 1.1-1.9; 3. removing the solvent from the product obtained in step 2 by a rotary evaporator, and finally obtaining an isocyanate-terminated medical polyurethane adhesive, which is stored in a dry environment. The curing time and product modulus are controlled by the content of reactive isocyanate groups.

[0003] At present, the water-based polyurethane used for the adhesive layer still cannot meet the performance requirements of adhesive products in the artificial leather field, which is reflected in the uniformity of bonding strength, the adaptability difference between curing time and operating process parameters, high temperature resistance, chemical resistance, and the balance between flexibility and hardness. Summary of the invention

[0004] In order to solve the problem that the curing time of the polyurethane adhesive in the prior art is difficult to control, resulting in poor moldability, high temperature resistance, chemical resistance and flexibility-hardness balance, the present application provides a multi-branched water-based polyurethane adhesive with controllable curing time. By utilizing the advantageous combination of linear polyurethane and hyperbranched polyurethane, a controllable number of OH functional groups are introduced into the traditional linear polyurethane molecular chain and / or the molecular chain end, and a multi-branched water-based polyurethane dispersion is formed and then mixed with a curing agent containing polyisocyanate to achieve the preparation of an adhesive with controllable curing time.

[0005] This application adopts the following technical solutions:

[0006] According to one aspect of the present application, a multi-branched time-controlled curing waterborne polyurethane adhesive is provided, comprising the following components:

[0007] Aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups;

[0008] A curing agent B containing polyisocyanate;

[0009] The polyhydroxy-containing aqueous multi-branched polyurethane dispersion A is obtained by introducing a controllable number of OH functional groups into the molecular chain and / or the molecular chain end of the linear polyurethane.

[0010] In the present application, the curing agent B containing polyisocyanate is a commercial polyisocyanate curing agent, and those skilled in the art can select it according to their needs.

[0011] Optionally, the multi-branched controllably curable waterborne polyurethane adhesive contains the following components in weight percentage:

[0012] Aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups 90% to 100%;

[0013] Contains 0% to 10% of a curing agent B of polyisocyanate; wherein the lower limit of the content of the curing agent B is not 0.

[0014] The sum of the component percentages is 100%.

[0015] Optionally, in the aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups, the content of OH is 0.1%-0.5% by weight of the linear polyurethane.

[0016] According to another invention of the present application, a method for preparing the above-mentioned multi-branched time-controlled curing waterborne polyurethane adhesive is provided, characterized in that it comprises the following steps:

[0017] S1, obtaining a water-based multi-branched polyurethane dispersion A containing polyhydroxyl groups;

[0018] S2. Evenly mix the water-based multi-branched polyurethane dispersion A containing polyhydroxyl groups and the curing agent B containing polyisocyanate to obtain the multi-branched water-based polyurethane adhesive that can be cured in controlled time.

[0019] Optionally, in step S1, the preparation process of the polyhydroxy-containing aqueous multi-branched polyurethane dispersion A comprises the following steps:

[0020] S1-1, polyolizing the oligomer and removing moisture under vacuum conditions, releasing the vacuum under an inert atmosphere, sequentially adding a polyol chain extender, a polyisocyanate, and an organic bismuth catalyst to the oligomer polyol, and performing a prepolymerization reaction to obtain an NCO-terminated polyurethane prepolymer;

[0021] S1-2, adding acetone to the NCO-terminated polyurethane prepolymer to adjust the viscosity, cooling to the neutralization temperature, adding a neutralizing agent for neutralization, and obtaining an ionic polyurethane prepolymer acetone solution;

[0022] S1-3, adding water to the acetone solution of the ionic polyurethane prepolymer and stirring to obtain an aqueous dispersion of the polyurethane prepolymer;

[0023] S1-4, adding an aqueous solution containing a polyamine chain extender and a dialkanolamine to the aqueous dispersion of the polyurethane prepolymer to carry out a chain extension reaction, and then removing acetone under reduced pressure to obtain an aqueous multi-branched polyurethane dispersion A containing polyhydroxy groups.

[0024] Optionally, in step S1-1, the polyol is selected from at least one of polyneopentyl adipate glycol, polypropylene glycol, polyethylene glycol, polytetramethylene glycol, and polyethylene glycol monomethyl ether.

[0025] Optionally, in step S1-1, the polyol chain extender is selected from at least one of dimethylol propionic acid and 1,4-butanediol.

[0026] Optionally, in step S1-1, the polyisocyanate is selected from toluene diisocyanate.

[0027] Optionally, in step S1-2, the neutralizing agent is selected from triethylamine.

[0028] Optionally, in step S1-4, the polyamine chain extender is selected from at least one of hydroxyethylethylenediamine and diethylenetriamine.

[0029] Optionally, in step S1-4, the dialkanolamine is selected from diethanolamine.

[0030] Optionally, in step S1-1, the conditions for the prepolymerization reaction include: a reaction temperature of 70 to 90° C. and a reaction time of 1 to 5 hours.

[0031] Optionally, the conditions for the chain extension reaction in step S1-4 include: a reaction temperature of 25 to 50° C. and a reaction time of 20 to 40 min.

[0032] Optionally, the weight portions of the components added during the preparation of the polyhydroxy-containing aqueous multi-branched polyurethane dispersion A are as follows:

[0033] In step S1-1:

[0034]

[0035] In step S1-2:

[0036] 40-60 parts by weight of acetone;

[0037] 0.5 to 2 parts by weight of neutralizing agent;

[0038] In step S1-3:

[0039] 80-120 parts by weight of water;

[0040] In step S1-4:

[0041] 0.1 to 1 part by weight of polyamine chain extender;

[0042] Dialkanolamine 0-1 parts by weight;

[0043] 5 to 15 parts by weight of water.

[0044] According to another aspect, there is also provided a use of the multi-branched controllable time-curing waterborne polyurethane adhesive or the multi-branched controllable time-curing waterborne polyurethane adhesive obtained according to the preparation method in bonding an adhesive layer of artificial leather.

[0045] The beneficial effects of this application include:

[0046] The multi-branched time-controlled curing waterborne polyurethane adhesive of the present application comprises a waterborne multi-branched polyurethane dispersion A containing polyhydroxyl groups and a curing agent B containing polyisocyanate, and combines the advantages of linear polyurethane and hyperbranched polyurethane, introduces a controllable number of OH functional groups into the molecular chain and / or the molecular chain end of the traditional linear polyurethane, prepares a multi-branched waterborne polyurethane dispersion, and then mixes it with a certain amount of curing agent containing polyisocyanate to obtain an adhesive that can be used for the adhesive layer of artificial leather. The hyperbranched polymer of the adhesive contains a large number of terminal functional groups, the molecular chain is not easy to entangle, the viscosity of the melt and the solution is low, it is helpful to form a uniform polymer film, and has excellent properties such as controllable curing, good film-forming property, high temperature resistance, chemical resistance, etc. DETAILED DESCRIPTION

[0047] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0048] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0049] Unless otherwise specified, conventional methods were used for testing and instrument settings were those recommended by the manufacturer.

[0050] Example 1 Preparation of aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups

[0051] In a three-necked flask equipped with a stirrer and a thermometer, 16.00 g of polyneopentyl adipate diol (Mn2000), 40.00 g of polypropylene glycol (Mn2000), and 0.60 g of polyethylene glycol (Mn600) were added, the oil bath was set to 100°C, heated to melt, vacuum dehydrated for 1 h, flushed with nitrogen, cooled to below 60°C, 1.44 g of dimethylolpropionic acid, 0.30 g of 1,4-butanediol were added, stirred until uniform and free of particles, 8.56 g of toluene diisocyanate was added, and after observing that the temperature in the system was stable, about 0 .12g organic bismuth catalyst, set the oil bath temperature to 80℃, stir the reaction for 2h, cool to below 60℃, add 60ml acetone, stir evenly, add 1.09g triethylamine, stir for 5 minutes, add 105g water to disperse evenly, add a mixed solution of 0.54g diethanolamine, 0.27g hydroxyethylethylenediamine and 9g water, stir for 30min, and then remove acetone under reduced pressure to obtain a white emulsion, i.e., a polyhydroxy water-based multi-branched polyurethane dispersion A, with a solid content of 37.68% and branched end OH mass / PU mass = 0.32%.

[0052] Example 2 Preparation of aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups

[0053] In a three-necked flask equipped with a stirrer and a thermometer, 16.00 g of polyneopentyl adipate diol (Mn2000), 40.00 g of polypropylene glycol (Mn2000), and 1.00 g of polyethylene glycol (Mn2000) were added, the oil bath was set to 100°C, heated to melt, vacuum dehydrated for 1 h, flushed with nitrogen, cooled to below 60°C, 1.44 g of dimethylol propionic acid, 0.20 g of 1,4-butanediol were added, stirred until uniform and free of particles, 8.56 g of toluene diisocyanate was added, and the temperature in the system was observed. After the temperature stabilizes, add about 0.12g of organic bismuth catalyst, set the oil bath temperature to 80℃, stir and react for 2h, cool to below 60℃, add 48g of acetone, stir evenly, add 1.07g of triethylamine, stir for 5 minutes, add 101g of water to disperse evenly, add a mixed solution of 0.12g of diethylenetriamine, 0.50g of hydroxyethylethylenediamine and 9g of water, stir for 30min, and then remove acetone under reduced pressure to obtain a white slightly blue emulsion, i.e., a polyhydroxy waterborne multi-branched polyurethane dispersion A, with a solid content of 38.55%. The branch end OH mass / PU mass = 0.12%.

[0054] Example 3 Preparation of aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups

[0055] In a three-necked flask equipped with a stirrer and a thermometer, 16.00 g of polyneopentyl adipate diol (Mn2000), 30.00 g of polypropylene glycol (Mn2000), 1.00 g of polyethylene glycol (Mn2000), and 1.80 g of polypropylene glycol (Mn400) were added, the oil bath was set to 100°C, heated to melt, vacuum dehydrated for 1 h, flushed with nitrogen, cooled to below 60°C, 1.44 g of dimethylol propionic acid, 0.40 g of 1,4-butanediol, and 0.45 g of polyethylene glycol monomethyl ether (Mn750) were added, stirred until uniform and free of particles, and 8. 52g, after observing that the temperature in the system is stable, add about 0.12g of organic bismuth catalyst, set the oil bath temperature to 80°C, stir and react for 2h, cool to below 60°C, add 60 ml of acetone, stir evenly, add 1.08g of triethylamine, stir for 5 minutes, add 100g of water to disperse evenly, add a mixed solution of 0.12g of diethylenetriamine, 0.52g of hydroxyethylethylenediamine and 5g of water, stir for 30min, and then remove acetone under reduced pressure to obtain a white emulsion, i.e., a polyhydroxy water-based multi-branched polyurethane dispersion A, with a solid content of 36.92% and branched end OH mass / PU mass = 0.14%.

[0056] Examples 4 to 6 Preparation of multi-branched time-controlled curing waterborne polyurethane adhesives

[0057] The polyhydroxy waterborne multi-branched polyurethane dispersion A prepared in Examples 1 to 3 was respectively mixed with a commercial polyisocyanate curing agent 3100 (Covestro) was mixed, and the curing agent was added in an amount of 5%, and multi-branched controllable time-curing water-based polyurethane adhesives were obtained, which were marked as adhesive #1, adhesive #2, and adhesive #3.

[0058] Test Case

[0059] The curing time of the adhesive can be determined as follows:

[0060] (1) Cut the substrate PVC into several strips of 25 mm*100 mm, apply adhesive, place in a 120°C oven for 5 min, take out, and leave at room temperature.

[0061] (2) At fixed intervals (which can be set according to the need for judgment accuracy), take a piece of glue-coated sample and bond it to the clean PVC sample, and roll it manually.

[0062] (3) Repeat step (2) until there is no stickiness between the coated sample and the clean PVC sample when peeled off, which is considered to be cured.

[0063] As an example, the above method is used to test the curing time of adhesive #1, adhesive #2, and adhesive #3. The test results are as follows:

[0064] adhesive #1 Adhesive #2 Adhesive #3 Adhesive Curing time / hour 2 5 4

[0065] The curing time of the waterborne polyurethane adhesive of the present application can be adjusted by adjusting the number of OH functional groups on the waterborne multi-branched polyurethane dispersion A containing polyhydroxy groups in the raw material formula. The method for obtaining the adhesive formula with a specific curing time is:

[0066] According to the curing time requirements, several formulas with step-by-step increase in OH functional group content can be designed to obtain multiple adhesives with different curing times. The above-mentioned adhesive curing time judgment method is used to determine the raw material formula corresponding to the adhesive closest to the target curing time.

[0067] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A multi-branched time-controlled curing water-based polyurethane adhesive, characterized in that: The components include: Aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups; A curing agent B containing polyisocyanate; The polyhydroxy-containing aqueous multi-branched polyurethane dispersion A is obtained by introducing a controllable number of OH functional groups into the molecular chain and / or the molecular chain end of the linear polyurethane.

2. The multi-branched time-controlled curing water-based polyurethane adhesive according to claim 1, characterized in that: The multi-branched controlled time-curing waterborne polyurethane adhesive contains the following components in weight percentage: Aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups 90% to 100%; Containing polyisocyanate curing agent B 0% to 10%; The sum of the component percentages is 100%.

3. The multi-branched time-controlled curing water-based polyurethane adhesive according to claim 1, characterized in that: In the aqueous multi-branched polyurethane dispersion A containing polyhydroxyl groups, the content of OH is 0.1% to 0.5% by weight of the linear polyurethane.

4. The method for preparing the multi-branched time-controlled curing waterborne polyurethane adhesive according to any one of claims 1 to 3, characterized in that: The steps include: S1, obtaining a water-based multi-branched polyurethane dispersion A containing polyhydroxyl groups; S2. Evenly mix the water-based multi-branched polyurethane dispersion A containing polyhydroxyl groups and the curing agent B containing polyisocyanate to obtain the multi-branched water-based polyurethane adhesive that can be cured in controlled time.

5. The preparation method according to claim 4, characterized in that: In step S1, the preparation process of the polyhydroxy-containing aqueous multi-branched polyurethane dispersion A comprises the following steps: S1-1, polyolizing the oligomer and removing moisture under vacuum conditions, releasing the vacuum under an inert atmosphere, sequentially adding a polyol chain extender, a polyisocyanate, and an organic bismuth catalyst to the oligomer polyol, and performing a prepolymerization reaction to obtain an NCO-terminated polyurethane prepolymer; S1-2, adding acetone to the NCO-terminated polyurethane prepolymer to adjust the viscosity, cooling to the neutralization temperature, adding a neutralizing agent for neutralization, and obtaining an ionic polyurethane prepolymer acetone solution; S1-3, adding water to the acetone solution of the ionic polyurethane prepolymer and stirring to obtain an aqueous dispersion of the polyurethane prepolymer; S1-4, adding an aqueous solution containing a polyamine chain extender and / or a dialkanolamine to the aqueous dispersion of the polyurethane prepolymer to carry out a chain extension reaction, and then removing acetone under reduced pressure to obtain an aqueous multi-branched polyurethane dispersion A containing polyhydroxy groups.

6. The preparation method according to claim 5, characterized in that: In step S1-1, the polyol is selected from at least one of polyneopentyl adipate glycol, polypropylene glycol, polyethylene glycol, polytetrahydrofuran diol, and polyethylene glycol monomethyl ether; Preferably, in step S1-1, the polyol chain extender is selected from at least one of dimethylol propionic acid and 1,4-butanediol; Preferably, in step S1-1, the polyisocyanate is selected from toluene diisocyanate.

7. The preparation method according to claim 5, characterized in that: In step S1-2, the neutralizing agent is selected from triethylamine.

8. The preparation method according to claim 4, characterized in that: In step S1-4, the polyamine chain extender is selected from at least one of hydroxyethylethylenediamine and diethylenetriamine; Preferably, in step S1-4, the dialkanolamine is selected from diethanolamine.

9. The preparation method according to claim 4, characterized in that: In step S1-1, the conditions of the prepolymerization reaction include: a reaction temperature of 70 to 90° C. and a reaction time of 1 to 5 h; Preferably, the conditions for the chain extension reaction in step S1-4 include: a reaction temperature of 25 to 50° C. and a reaction time of 20 to 40 min.

10. Use of the multi-branched time-controlled curing aqueous polyurethane adhesive according to any one of claims 1 to 3 or the multi-branched time-controlled curing aqueous polyurethane adhesive obtained by the preparation method according to any one of claims 4 to 9 in bonding artificial leather adhesive layers.

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