Water-based single-component adhesive for spraying as well as preparation method and application of water-based single-component adhesive

Abstract

The invention discloses a water-based single-component adhesive for spraying as well as a preparation method and application of the water-based single-component adhesive. The adhesive is prepared from the following components in parts by weight: 94 to 98 parts of a water-based polyurethane dispersion, 0.02 to 0.05 part of a wetting agent, 1 to 3 parts of a high-shear thickening agent and 0.05 to 1 part of a medium-shear thickening agent, wherein the ratio of the high shear thickening agent to the medium shear thickening agent ranges from 20: 1 to 20: 6. The water-based single-component adhesive for spraying disclosed by the invention shows a relatively stable rheological curve within a middle shear rate range of 1rpm to 30rpm, is close to the performance of Newtonian fluid, and is beneficial to realizing automatic continuous spraying in a vamp assembling process; the gun blocking problem is avoided in the spraying process, the glue applying amount is stable, and glue does not accumulate on a nozzle; meanwhile, good water resistance is achieved, the relevant performance requirements after fabric parts on the vamps are assembled and attached can be met, and the glue failure rate and the defective rate are reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of water-based adhesives, and particularly relates to a water-based one-component adhesive for spraying, a preparation method thereof, and an application thereof in the bonding of shoe upper fabrics. Background Art

[0002] In recent years, the annual output of various shoes in China has exceeded 12 billion pairs, accounting for 70% of the total global shoe production. China is the world's largest shoe manufacturing base and the largest shoe exporter. With the rapid development of China's shoe-making industry, the traditional development model of pursuing quantity expansion and low-price competition no longer has an advantage. Under the background of economic transformation, improving the technical level and product quality will be an inevitable trend for the future development of the shoe-making industry.

[0003] Shoe adhesives are one of the most important materials in the shoe-making process, which also determine the quality and service life of shoes. At the same time, the upgrade of adhesive products in the shoe-making process is one of the keys to improving shoe-making efficiency. With the continuous development of the shoe-making industry and the increasingly strict requirements of environmental protection regulations in various countries, polyurethane adhesives and chloroprene adhesives containing volatile solvents can no longer meet the needs of industry development, and the demand for environmentally friendly shoe adhesives has become increasingly urgent. Water-based polyurethane adhesives are adhesives that use water instead of organic solvents as the dispersion medium, and are safe, non-toxic, and non-polluting to the environment during use.

[0004] At present, the main processing technology of shoe adhesives is to manually coat them on substrates such as shoe soles, dry the moisture through a drying tunnel and activate the glue, then assemble and bond different shoe materials, and finally press and form them through a press. However, the defect of the manual gluing process is low production efficiency and high cost. Against the background of rising labor costs, all industries are actively carrying out automation transformation, and automated production has become an inevitable trend in the future. The automated processing technology replaces the manual gluing process with mechanical spraying. In the past, it took about half a year to complete the process from shoe design, manufacturing to sales; in the future, it is expected to complete this series of processes within a week. Currently, the water-based adhesives used for automated spraying have problems such as long drying time, spraying gun clogging, and high defect rate. These problems have greatly restricted the progress of automation in the shoe-making industry.

[0005] Automated shoe-making requires the use of an automatic spraying process, which puts higher requirements on water-based shoe adhesives. Compared with traditional water-based shoe adhesives applied by manual brushing, water-based shoe adhesives suitable for automatic spraying need to have the following characteristics:

[0006] (1) It can dry quickly and improve the drying efficiency;

[0007] (2) It can be sprayed evenly to ensure that there is no glue accumulation on the surface of the substrate and reduce the defect rate;

[0008] (3) The spraying process is not prone to gun clogging, reducing the frequency of cleaning the spray gun and improving production efficiency;

[0009] At present, the continuous mass production of oil-based adhesives for spraying has been achieved in the industry. However, due to the increasing attention to environmental protection, oil-based adhesives with high VOC content can no longer meet the requirements of environmental protection and are not conducive to the health of on-site construction workers. Water-based adhesives can well solve these problems.

[0010] In order to make the whole shoe have better water resistance and reduce the glue opening rate on the production line, a curing agent is usually added to the water-based adhesive. Since the finished glue has a certain open time after adding the curing agent, it usually causes problems such as blocking the pipeline and nozzle during the spraying process of the water-based adhesive, and is not conducive to equipment cleaning.

[0011] At present, there are also a small number of single-component water-based adhesives for spraying on the market, but they are expensive and have a large performance gap compared with oil-based adhesives and finished adhesives using curing agents.

[0012] In summary, how to effectively solve the problems of gun clogging and uneven spraying existing in the automatic spraying process of water-based adhesives, realize automatic continuous spraying, and meet the application performance is one of the current technical difficulties to be overcome in this field. Summary of the Invention

[0013] The purpose of the present invention is to provide a single-component water-based adhesive for spraying, which has excellent rheological properties and continuous spraying stability while meeting the requirements of substrate bonding strength and water resistance; applying this adhesive to the shoe-making field can improve production efficiency and is very suitable for the fully automatic spraying process in the shoe-making process.

[0014] Another purpose of the present invention is to provide a preparation method of this single-component water-based adhesive for spraying.

[0015] Another purpose of the present invention is to provide the application of this single-component water-based adhesive for spraying.

[0016] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0017] A single-component water-based adhesive for spraying, comprising the following components in parts by weight:

[0018] 94-98 parts of water-based polyurethane dispersion, such as 94, 95, 96, 97, 98 parts, etc., preferably 95-97 parts;

[0019] 0.02-0.05 parts of wetting agent, such as 0.02, 0.03, 0.04, 0.05 parts, etc., preferably 0.03-0.04 parts;

[0020] 1 - 3 parts of high - shear thickener, such as 1, 1.5, 2, 2.5, 3, 3 parts, etc., preferably 1.5 - 2.5 parts;

[0021] 0.05 - 1 part of medium - shear thickener, such as 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.85, 0.9 parts, etc., preferably 0.1 - 0.75 parts;

[0022] Among them, no non - ionic hydrophilic capping agent is added during the preparation process of the aqueous polyurethane dispersion;

[0023] The mass ratio of the high - shear thickener to the medium - shear thickener is between 20:1 and 20:6, such as 20:1, 20:2, 20:3, 20:4, 20:5, 20:6, etc., preferably between 20:2 and 20:4.

[0024] In some specific embodiments, no non - ionic hydrophilic capping agent is added during the preparation process of the aqueous polyurethane dispersion. Those skilled in the art know that conventional aqueous polyurethane dispersions usually add non - ionic hydrophilic capping agents. For example, the aqueous polyurethane dispersion Adwel 1665A containing a capping agent from Wanhua Chemical is commonly used in the aqueous polyurethane adhesive industry. In the present invention, the key in the preparation process of the aqueous polyurethane dispersion is not to add non - ionic hydrophilic capping agents, and other preparation processes can refer to the existing technology.

[0025] An exemplary preparation method, for example, the preparation method of the aqueous polyurethane dispersion includes the following steps:

[0026] 1) React a macromolecular polyol and a diisocyanate in an organic solvent to form a diisocyanate prepolymer. The reaction is carried out under the condition of a catalyst, and no non - ionic hydrophilic capping agent is added during the reaction process;

[0027] 2) Add a hydrophilic chain extender to the diisocyanate prepolymer for chain - extension reaction, and obtain an aqueous polyurethane crude emulsion through shear dispersion. Remove the organic solvent in the aqueous polyurethane crude emulsion and adjust its pH to 6.0 - 9.0 to obtain the aqueous polyurethane dispersion.

[0028] In some specific embodiments, in the preparation of the aqueous polyurethane dispersion, the macromolecular polyol is selected from one or two of polyester diol and polyether diol, and its relative molecular mass is 1000-4000, such as 1000, 1500, 2000, 2500, 3000, 3500, 4000, etc., preferably 2000-3000; preferably selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol-propylene glycol, polytetrahydrofuran ether diol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, 1,4-butanediol adipate diol, neopentyl glycol adipate diol, 1,6-hexanediol adipate diol, neopentyl glycol adipate 1,6-hexanediol diol and polyphenyl anhydride diethylene glycol, more preferably two or three of 1,4-butanediol adipate diol, 1,6-hexanediol adipate diol and polyphenyl anhydride diethylene glycol.

[0029] The diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, preferably selected from one or two of isophorone diisocyanate and hexamethylene diisocyanate.

[0030] The catalyst is selected from at least one of dibutyltin oxide, stannous octoate or dibutyltin dilaurate, bis-(2-ethylhexanoic acid)tin, bismuth neodecanoate, bismuth 2-ethylhexanoate.

[0031] The hydrophilic chain extender is selected from at least one of small molecule diamine chain extenders containing active hydrogen and sulfonic acid type hydrophilic chain extenders containing active hydrogen; preferably, the sulfonic acid type hydrophilic chain extender containing active hydrogen is selected from one or more of sodium 2-(2-aminoethyl)aminoethanesulfonate, sodium 2-(2-aminoethyl)aminopropanesulfonate, 1,4-butanediol-2-sulfonate and 1,2-dihydroxy-3-propanesulfonate, preferably sodium 2-(2-aminoethyl)aminoethanesulfonate; the small molecule diamine chain extender containing active hydrogen is selected from one or more of ethylenediamine, hexamethylenediamine, pentamethylenediamine, hydroxyethyl ethylenediamine, isophorone diamine, 4,4-diphenylmethanediamine and diethanolamine, preferably selected from one or two of hydroxyethyl ethylenediamine and isophorone diamine.

[0032] The organic solvent is selected from low boiling point organic solvents with a boiling point of 40°C to 85°C, such as low boiling point organic solvents with a boiling point of 45°C, 50°C, 60°C, 70°C, 80°C. Those skilled in the art can make a conventional selection within this boiling point range, preferably selected from acetone or butanone, more preferably acetone.

[0033] In some specific embodiments, based on the total mass of the solid content in the aqueous polyurethane dispersion being 100%, the addition amount of the macromolecular polyol in step 1) is 50 - 74 wt% of the total mass of the solid content, such as 52 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 74 wt%, etc., and preferably 55 - 73 wt%; the addition amount of the diisocyanate is 14 - 39 wt% of the total mass of the solid content, such as 15 wt%, 18 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 38 wt%, etc., and preferably 16 - 32 wt%; the addition amount of the organic solvent is 0.05 - 0.3 times the total mass of the solid content, such as 0.1, 0.15, 0.2, 0.25, 0.3 times, and preferably 0.1 - 0.2 times; the addition amount of the catalyst is 0 - 500 ppm, based on the total mass of the macromolecular polyol and the diisocyanate, such as 0 ppm, 5 ppm, 10 ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, etc.

[0034] For the reaction in step 1), the reaction temperature is 70 - 90 °C, such as 75 °C, 80 °C, 85 °C, 90 °C, etc., and the reaction time is 1 - 3 h, such as 2 h.

[0035] In step 2), based on the total mass of the solid content in the aqueous polyurethane dispersion being 100%, the addition amount of the hydrophilic chain extender is 1.5 - 2.7 wt% of the total mass of the solid content, such as 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, etc., and preferably 1.7 - 2.5 wt%.

[0036] The reaction temperature of the chain extension reaction is 30 - 50 °C, such as 35 °C, 40 °C, 45 °C, 50 °C, etc., and the reaction time is 1 - 30 min, such as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, etc.

[0037] Among them, the total mass of the solid content in the aqueous polyurethane dispersion refers to the total solid content in the aqueous polyurethane dispersion to be prepared, which can be regarded as the total mass of the solid content in the theoretically prepared aqueous polyurethane dispersion, that is, the total solid content obtained theoretically.

[0038] In the present invention, the aqueous polyurethane dispersion for spraying does not include a non-ionic hydrophilic capping agent component. This non-ionic hydrophilic capping agent is a monofunctional component containing a polyethoxy chain segment that is reactive to isocyanate, and its relative molecular mass is 500 - 3000, such as 1000, 1500, 2000, 2500, 3000, etc.; preferably it is a polyalkylene oxide ether containing at least one hydroxyl group, and the polymerization unit of the polyalkylene oxide ether is propylene oxide and / or ethylene oxide, more preferably ethylene oxide; wherein, preferably the number of ethylene oxide units in each molecule of the polyalkylene oxide ether is 5 - 200, such as 10, 50, 80, 100, 120, 150, 180, 200, etc., more preferably 10 - 80;

[0039] In some specific embodiments, the solid content of the aqueous polyurethane dispersion is 42 - 49 wt%, such as 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, etc., preferably 43 - 46 wt%; the average particle size of the aqueous polyurethane dispersion is 150 - 250 nm, such as 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, etc., preferably 180 - 230 nm; the viscosity of the aqueous polyurethane dispersion emulsion at 25 °C is 10 - 2000 cps, such as 20 cps, 50 cps, 80 cps, 100 cps, 200 cps, 300 cps, 400 cps, 500 cps, 600 cps, 700 cps, 800 cps, 900 cps, 1000 cps, 1200 cps, 1500 cps, 1800 cps, 2000 cps, etc., preferably 50 - 1000 cps.

[0040] In some specific embodiments, the wetting agent is a polyether-modified polysiloxane wetting agent, preferably selected from one or both of TEGO-KL245 of Degussa and BYK-349 of BYK Chemie.

[0041] In some specific embodiments, the high-shear thickening agent and the medium-shear thickening agent are polyurethane associative thickening agents. Here, the high-shear thickening agent and the medium-shear thickening agent are conventional terms in the art, and those skilled in the art can select appropriate types. For example, the high-shear thickening agent is preferably selected from at least one of Vesmody U300 and Vesmody U300E, Acrysol RM-8W of Dow Chemical, Coapur 817BB and Coapur 870W of Arkema Chemical, and more preferably Vesmody U300E. The medium-shear thickening agent is preferably selected from one or more of Vesmody U604 and Vesmody U601 of Wanhua Chemical, Acrysol RM-3030 of Dow Chemical, Coapur 2501 and Coapur 3025 of Arkema Chemical, and more preferably Vesmody U601.

[0042] The inventors of the present application unexpectedly found that the above-mentioned one-component aqueous adhesive presents an approximately Newtonian fluid state within the shear range of 1 rpm - 30 rpm, which can fully meet the requirements of automatic spraying of shoe glue without the problem of gun clogging during the automatic spraying process. This is achieved by the synergistic effect of the medium-shear thickening agent, the high-shear thickening agent, and the aqueous polyurethane dispersion without adding non-ionic hydrophilic end-capping agents during the preparation process, which was difficult to predict before this application.

[0043] On the other hand, for a preparation method of the aforementioned aqueous one-component adhesive for spraying, mix each raw material component in the required amounts and adjust the viscosity to 6000 - 10000 cps, such as 6000 cps, 7000 cps, 8000 cps, 9000 cps, 10000 cps, etc., and then the aqueous one-component adhesive can be prepared.

[0044] In a preferred embodiment, the preparation method of the aforementioned aqueous one-component adhesive for spraying includes the following steps:

[0045] 1) Mix and stir the aqueous polyurethane dispersion and the wetting agent in proportion to obtain a mixture; the stirring time is 5 - 10 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc., preferably 5 - 8 minutes; the stirring speed is 100 - 600 revolutions per minute, such as 100 revolutions per minute, 200 revolutions per minute, 300 revolutions per minute, 400 revolutions per minute, 500 revolutions per minute, 600 revolutions per minute, etc., preferably 200 - 400 revolutions per minute;

[0046] 2) Then mix the mixture obtained in step 1) with a high-shear thickener and stir to adjust the viscosity to 2500-4000 cps, such as 3000 cps, 3500 cps, 4000 cps, etc., preferably 3000-3500 cps; the stirring time is 15-45 minutes, such as 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, etc., preferably 20-40 minutes; the stirring speed is 200-1000 revolutions per minute, such as 300 revolutions per minute, 400 revolutions per minute, 500 revolutions per minute, 600 revolutions per minute, 700 revolutions per minute, 800 revolutions per minute, 900 revolutions per minute, 1000 revolutions per minute, etc., preferably 400-600 revolutions per minute;

[0047] 3) Then mix the mixture obtained in step 2) with a medium-shear thickener and stir to adjust the viscosity to 6000-10000 cps, such as 6000 cps, 7000 cps, 8000 cps, 9000 cps, 10000 cps, etc., preferably 6500-9000 cps; the stirring time is 15-45 minutes, such as 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, etc., preferably 20-40 minutes; the stirring speed is 200-1000 revolutions per minute, such as 300 revolutions per minute, 400 revolutions per minute, 500 revolutions per minute, 600 revolutions per minute, 700 revolutions per minute, 800 revolutions per minute, 900 revolutions per minute, 1000 revolutions per minute, etc., preferably 400-600 revolutions per minute.

[0048] In another aspect of the present invention, there is also provided the use of the sprayable aqueous one-component adhesive as described above or the sprayable aqueous one-component adhesive prepared by the method as described above in the bonding of shoe upper fabrics.

[0049] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0050] 1) In the raw material components of the sprayable aqueous one-component adhesive of the present invention, common non-ionic end-capping agents are not added, so that the polymer molecular chain ends do not carry hydrophilic groups. When an associative high-shear thickener and a medium-shear thickener are used in combination, it is easier to obtain a stable rheological curve at medium shear rates, so that the glue output is not uneven due to fluctuations in the air pressure of the spray gun during actual spraying.

[0051] 2) The sprayable aqueous one-component adhesive of the present invention has excellent rheological properties. The glue film after spraying is uniform and does not accumulate glue, which greatly reduces the defective product rate during the construction process and realizes the automatic spraying process to a greater extent, improving production efficiency.

[0052] 3) The production process of the sprayable aqueous one-component adhesive of the present invention is simple, easy to operate, safe and environmentally friendly.

[0053] 4) Using the water-based one-component adhesive for spraying described in the present invention for automated spraying is more convenient than the manual coating process, reducing labor costs and the amount of glue loss, thereby achieving cost reduction in the production process. Description of the Drawings

[0054] Figure 1 It is the rheological curve of the adhesive in the examples and comparative examples of the present invention. Detailed Embodiments

[0055] In order to be able to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the examples, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein.

[0056] <Source of Raw Materials>

[0057] The sources of the raw materials in the examples of the present invention are as follows. Unless otherwise specified, they are all ordinary raw materials purchased from the market:

[0058] Poly(adipic acid-1,4-butanediol)diol, Mn = 3000 g / mol ( WHP-304, Wanhua Chemical);

[0059] Polyphenyl anhydride diethylene glycol, Mn = 2000 g / mol (PH-56, Stepan, USA);

[0060] Hexamethylene diisocyanate ( HDI, Wanhua Chemical);

[0061] Isophorone diisocyanate ( IPDI, Wanhua Chemical);

[0062] N-(2-Aminoethyl)-2-aminoethanesulfonate ( A95);

[0063] Bismuth neodecanoate (Merck KGaA, Germany).

[0064] <Testing Method>

[0065] The testing method of the water-based one-component adhesive involved in the present invention in the application of upper fabric bonding is as follows:

[0066] (1) Rheological property testing

[0067] Refer to GB / T2794-2013 (Brookfield LV, 63#) to test the viscosity curves of the prepared finished glue at different rotation speeds of 1.5 rpm, 3 rpm, and 12 rpm.

[0068] (2) Peel strength test

[0069] Prepare a glue film with a dry film thickness of about 50 μm (7 cm long × 5 cm wide), two pieces of elastic cloth (10 cm long × 6 cm wide), and press them together using a hot press (150 °C × 60 s) with a pressure of 0.2 MPa to obtain test pieces. After the test pieces are cooled, cut them into long strips of equal width (10 cm long × 1 cm wide), clamp them between the upper and lower fixtures of a tensile testing machine, set the fixture moving speed to 200 mm / min, repeat the test on 3 specimens, and read the average peel strength value.

[0070] (3) Peel strength test after water washing

[0071] Select the test specimens described in part (2) with a uniform peeling surface. Immerse them in hot water at 60 °C for 2 hours, remove and dry the moisture, and immediately conduct the peel strength test after water washing. Clamp the test strips between the upper and lower fixtures of a tensile testing machine, set the fixture moving speed to 200 mm / min, repeat the test on 3 specimens, and the average peel strength value read is the peel strength after water washing.

[0072] (4) High temperature and high humidity resistance test

[0073] The method for preparing the test strips is the same as that described in part (2). Place the cut test strips in a constant temperature and humidity chamber at 70 °C × 95% temperature and humidity conditions, hang a weight of 300 g, and record the time of glue separation.

[0074] The present invention will be further described below in conjunction with specific embodiments, but it does not constitute any limitation.

[0075] Preparation example

[0076] Preparation of aqueous polyurethane dispersion:

[0077] (1) Add 220 g of poly(butylene adipate) diol, 110 g of polydiethylene glycol phthalate, 23 g of hexamethylene diisocyanate, 15 g of isophorone diisocyanate, 0.022 g of bismuth neodecanoate, and 63 g of acetone to a four-necked flask equipped with a reflux condenser, a thermometer, and a mechanical stirrer. Stop the reaction after reacting at 85 °C for 3 h to obtain an isocyanate prepolymer;

[0078] (2) Add 5.7 g of A95 to the prepolymer capped with diisocyanate in step (1). After reacting at 45 °C for 15 min, shear and disperse to obtain an aqueous polyurethane crude emulsion. Remove the organic solvent from the aqueous polyurethane crude emulsion and adjust its pH to 7.0 to obtain an aqueous polyurethane dispersion.

[0079] Example 1

[0080] The one-component waterborne adhesive of this embodiment includes the following parts by weight:

[0081] 95 parts of waterborne polyurethane dispersion,

[0082] 0.036 part of TEGO-KL245 (wetting agent),

[0083] 1.9 parts of U300E (thickener),

[0084] 0.19 part of U601 (thickener);

[0085] The above waterborne one-component adhesive is prepared by the following steps:

[0086] Add the waterborne polyurethane dispersion (95 g) and the wetting agent TEGO-KL245 (0.36 g) into a stirring device, with a stirring speed of 400 revolutions per minute and a stirring time of 8 minutes; then add the thickener U300E (1.9 g) to the stirring device, with a stirring speed of 600 revolutions per minute and a stirring time of 20 minutes; U601 (0.19 g), with a stirring speed of 600 revolutions per minute and a stirring time of 20 minutes, adjust the viscosity to 6500 - 9000 cps, and discharge the material.

[0087] Example 2

[0088] The one-component waterborne adhesive of this embodiment includes the following parts by weight:

[0089] 96 parts of waterborne polyurethane dispersion,

[0090] 0.038 part of TEGO-KL245 (wetting agent),

[0091] 2 parts of Acrysol RM-8W (thickener),

[0092] 0.3 part of U601 (thickener);

[0093] The preparation method is the same as that of Example 1.

[0094] Example 3

[0095] The one-component waterborne adhesive of this embodiment includes the following parts by weight:

[0096] 94 parts of waterborne polyurethane dispersion,

[0097] 0.035 part of TEGO-KL245 (wetting agent),

[0098] 2 parts of Acrysol RM-8W (thickener),

[0099] 0.4 parts of Acrysol RM-3030 (thickener);

[0100] The preparation method is the same as that of Example 1.

[0101] Comparative Example 1

[0102] The commonly used water-based adhesive U54 (Covestro) for fabric spraying on the market was selected as the comparative example to conduct comparative tests on peel strength, peel strength after washing, high temperature and high humidity resistance, rheological properties, and laboratory spraying simulation.

[0103] Comparative Example 2

[0104] The water-based polyurethane dispersion Adwel1665A (Wanhua Chemical) containing a capping agent, which is commonly used in the water-based polyurethane adhesive industry, was used to replace the water-based polyurethane dispersion in Example 1, and other conditions were the same as those in Example 1. A comparative example was prepared to conduct comparative tests on peel strength, peel strength after washing, high temperature and high humidity resistance, rheological properties, and laboratory spraying simulation.

[0105] Comparative Example 3

[0106] The one-component water-based adhesive of this example includes the following parts by weight:

[0107] 95 parts of water-based polyurethane dispersion,

[0108] 0.036 parts of TEGO-KL245 (wetting agent),

[0109] 4.75 parts of U300E (thickener),

[0110] 0.19 parts of U601 (thickener);

[0111] The preparation method is the same as that of Example 1.

[0112] Comparative Example 4

[0113] The one-component water-based adhesive of this example includes the following parts by weight:

[0114] 95 parts of water-based polyurethane dispersion,

[0115] 0.036 parts of TEGO-KL245 (wetting agent),

[0116] 0.475 parts of U300E (thickener),

[0117] 0.19 parts of U601 (thickener);

[0118] The preparation method is the same as that of Example 1.

[0119] The peel strength, peel strength after water washing, high temperature and high humidity resistance, rheological properties and laboratory spraying simulation tests were carried out on each example and comparative example, and the test results are shown as follows.

[0120] Table 1 Performance test results of waterborne one-component adhesives in examples and comparative examples

[0121]

[0122] As can be seen from Table 1, the adhesives prepared in Examples 1-3 have more prominent peel strength and peel strength after water washing compared with Comparative Example 1, indicating that the one-component waterborne adhesive prepared by the present invention has better substrate adhesion and water washing resistance, and can meet the requirements of the basic and demanding conditions of shoe adhesives.

[0123] Figure 1 The rheological curves of the adhesives in the examples and comparative examples are shown. It can be seen that the rheological curves of Examples 1-3 are comparable to those of Comparative Example 1, proving that the rheological requirements of general-purpose spraying waterborne adhesives for shoes on the market can be achieved by combining medium-shear and high-shear thickeners, and it is suitable for the fully automated spraying process in the shoe-making field. Compared with Comparative Example 2, Examples 1-3 are superior to the existing industrial product combination solutions, and the required performance can be achieved with only one emulsion. Compared with Comparative Examples 3-4, the required performance can be achieved only within the appropriate proportion range of medium-high shear thickeners.

[0124] <Laboratory spraying simulation test>

[0125] Put the prepared finished adhesives of the examples and comparative examples into the spray gun tank and conduct manual spray glue experiments.

[0126] Surface effect test: Spray the finished adhesive back and forth 5 times on the elastic cloth (elastic cloth size: 20 cm × 12 cm), and judge the spraying effect from factors such as spray volume and uniformity. The results are shown in Table 2 below.

[0127] Table 2 Laboratory spraying simulation performance of Examples 1-3 and Comparative Examples 1-4

[0128] Glue spraying amount Degree of uniformity Example 1 0.64g The surface is uniform and there are no glue accumulation points Example 2 0.6g The surface is uniform and there are no glue accumulation points Example 3 0.61g The surface is uniform and there are no glue accumulation points Comparative example 1 0.6g The surface is uniform and there are no glue accumulation points Comparative example 2 0.58g The surface is uniform and there is a small amount of glue accumulation Comparative example 3 0.57g The surface is uniform and there is a small amount of glue accumulation Comparative example 4 0.6g The surface is uniform and there are glue accumulation points

[0129] As can be seen from Table 2, compared with Comparative Example 1, in the spraying process of Examples 1-3, the atomization effect is good, the sizing amount is stable, and the surface of the substrate is uniform without sizing points. It shows that the solutions of Examples 1-3 can replace the widely used waterborne glue products in the market, and there will be no problems such as uneven sizing amount and unqualified product performance caused by air pressure fluctuations during the continuous automated spraying process. A small amount of sizing appears in Comparative Examples 2-4, proving that maintaining a relatively stable rheological curve within the medium-shear range is beneficial to spraying stability.

[0130] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An aqueous one-component adhesive for spraying, characterized in that, it comprises the following components in parts by weight: aqueous polyurethane dispersion 94 - 98 parts, preferably 95 - 97 parts; wetting agent 0.02 - 0.05 parts, preferably 0.03 - 0.04 parts; high-shear thickener 1 - 3 parts, preferably 1.5 - 2.5 parts; medium-shear thickener 0.05 - 1 part, preferably 0.1 - 0.75 part; wherein, no non-ionic hydrophilic capping agent is added during the preparation process of the aqueous polyurethane dispersion; the mass ratio of the high-shear thickener to the medium-shear thickener is 20:1 - 20:

6.

2. The aqueous one-component adhesive for spraying according to claim 1, characterized in that, the preparation method of the aqueous polyurethane dispersion comprises: 1) Reacting a macromolecular polyol and a diisocyanate in an organic solvent to form a diisocyanate prepolymer, the reaction is carried out in the presence of an optional catalyst, and no non-ionic hydrophilic capping agent is added during the reaction process; 2) Adding a hydrophilic chain extender to the diisocyanate prepolymer for chain extension reaction, obtaining an aqueous polyurethane crude emulsion through shear dispersion, removing the organic solvent in the aqueous polyurethane crude emulsion, and adjusting its pH to 6.0 - 9.0 to obtain the aqueous polyurethane dispersion.

3. The aqueous one-component adhesive for spraying according to claim 2, characterized in that, the macromolecular polyol is selected from one or two of polyester diol and polyether diol, the molecular weight of the macromolecular polyol is 1000 - 4000, preferably 2000 - 3000; preferably, the macromolecular polyol is selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol - propylene glycol, polytetrahydrofuran ether diol, polycaprolactone diol, polycarbonate diol, polyethylene adipate diol, 1,4 - butanediol adipate diol, neopentyl glycol adipate diol, 1,6 - hexanediol adipate diol, neopentyl glycol adipate 1,6 - hexanediol diol and polyphenylene anhydride diethylene glycol; more preferably, selected from two or three of 1,4 - butanediol adipate diol, 1,6 - hexanediol adipate diol and polyphenylene anhydride diethylene glycol; and / or the diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate, preferably, selected from one or two of isophorone diisocyanate and hexamethylene diisocyanate; and / or the catalyst is selected from at least one of dibutyltin oxide, stannous octoate or dibutyltin dilaurate, bis-(2 - ethylhexanoic acid)tin, bismuth neodecanoate, bismuth 2 - ethylhexanoate; and / or The hydrophilic chain extender is selected from at least one of small molecule diamine chain extenders containing active hydrogen and sulfonic acid type hydrophilic chain extenders containing active hydrogen; preferably, the sulfonic acid type hydrophilic chain extender containing active hydrogen is selected from one or more of sodium 2-(2-aminoethyl)aminoethanesulfonate, sodium 2-(2-aminoethyl)aminopropanesulfonate, 1,4-butanediol-2-sulfonate, and 1,2-dihydroxy-3-propanesulfonate, preferably sodium 2-(2-aminoethyl)aminoethanesulfonate; the small molecule diamine chain extender containing active hydrogen is selected from one or more of ethylenediamine, hexamethylenediamine, pentamethylenediamine, hydroxyethyl ethylenediamine, isophorone diamine, 4,4-diphenylmethane diamine, and diethanolamine, preferably selected from one or two of hydroxyethyl ethylenediamine and isophorone diamine; and / or The organic solvent is selected from low boiling point organic solvents with a boiling point of 40°C to 85°C, preferably selected from acetone or butanone, more preferably acetone.

4. The waterborne one-component adhesive for spraying according to claim 2 or 3, characterized in that, Based on the total mass of the solid content in the aqueous polyurethane dispersion being 100%, the addition amount of the macromolecular polyol in step 1) is 50-74 wt% of the total mass of the solid content, preferably 55-73 wt%; the addition amount of the diisocyanate is 14-39 wt% of the total mass of the solid content, preferably 16-32 wt%; the addition amount of the organic solvent is 0.05-0.3 times the total mass of the solid content, preferably 0.1-0.2 times; the addition amount of the catalyst is 0-500 ppm, based on the total mass of the macromolecular polyol and the diisocyanate; and / or For the reaction in step 1), the reaction temperature is 70-90°C and the reaction time is 1-3 h; and / or In step 2), based on the total mass of the solid content in the aqueous polyurethane dispersion being 100%, the addition amount of the hydrophilic chain extender is 1.5-2.7 wt% of the total mass of the solid content, preferably 1.7-2.5 wt%; and / or The reaction temperature of the chain extension reaction is 30-50°C and the reaction time is 1-30 min.

5. The waterborne one-component adhesive for spraying according to claim 2, characterized in that, The non-ionic hydrophilic capping agent is a monofunctional component containing a polyethoxy chain segment that is reactive to isocyanate, and its relative molecular mass is 500-3000; preferably, the non-ionic hydrophilic capping agent contains a polyalkylene oxide ether with at least one hydroxyl group, and the polymerization unit of the polyalkylene oxide ether is propylene oxide and / or ethylene oxide, preferably ethylene oxide; more preferably, the number of ethylene oxide units in each polymerization unit of the polyalkylene oxide ether is 5-200, more preferably 10-80.

6. The waterborne one-component adhesive for spraying according to claim 1, characterized in that, The average particle size of the aqueous polyurethane dispersion is 150-250 nm, preferably 180-230 nm; and / or The solid content of the aqueous polyurethane dispersion is 42-49 wt%, preferably 43-46 wt%; and / or The viscosity of the aqueous polyurethane dispersion emulsion at 25 °C is 10 - 2000 cps, preferably 50 - 1000 cps.

7. The waterborne one-component adhesive for spraying according to claim 1, characterized in that the wetting agent is a polyether-modified polysiloxane wetting agent, preferably selected from one or both of TEGO-KL245 of Degussa and BYK-349 of BYK Chemie; and / or the high-shear thickener and the medium-shear thickener are polyurethane associative thickeners; preferably, the high-shear thickener is selected from at least one of Vesmody U300 and Vesmody U300E of Wanhua Chemical, Acrysol RM-8W of Dow Chemical, Coapur 817BB and Coapur 870W of Arkema Chemical, preferably Vesmody U300E; and / or the medium-shear thickener is selected from at least one of Vesmody U604 and Vesmody U601 of Wanhua Chemical, Acrysol RM-3030 of Dow Chemical, Coapur 2501 and Coapur 3025 of Arkema Chemical, preferably Vesmody U601.

8. The waterborne one-component adhesive for spraying according to any one of claims 1 to 7, characterized in that the waterborne one-component adhesive for spraying exhibits properties close to those of a Newtonian fluid at a medium shear rate of 1 rpm - 30 rpm.

9. The preparation method of the waterborne one-component adhesive for spraying according to any one of claims 1 to 8, characterized in that each raw material component is mixed evenly and adjusted to a viscosity of 6000 - 10000 cps, then the waterborne one-component adhesive can be prepared; preferably, it includes the following steps: 1) Mix and stir the aqueous polyurethane dispersion and the wetting agent to obtain a mixture; preferably, the stirring time is 5 - 10 minutes, preferably 5 - 8 minutes; the stirring speed is 100 - 600 revolutions per minute, preferably 200 - 400 revolutions per minute; 2) Then mix and stir the mixture obtained in step 1) with the high-shear thickener and adjust to a viscosity of 2500 - 4000 cps, preferably 3000 - 3500 cps; preferably, the stirring time is 15 - 45 minutes, preferably 20 - 40 minutes; the stirring speed is 200 - 1000 revolutions per minute, preferably 400 - 600 revolutions per minute; 3) Then mix and stir the mixture in step 2) with the medium-shear thickener and adjust to a viscosity of 6000 - 10000 cps, preferably 6500 - 9000 cps; preferably, the stirring time is 15 - 45 minutes, preferably 20 - 40 minutes; the stirring speed is 200 - 1000 revolutions per minute, preferably 400 - 600 revolutions per minute.

10. The application of the waterborne one-component adhesive for spraying according to any one of claims 1 to 8 or the waterborne one-component adhesive for spraying prepared by the method according to claim 9 in the bonding of upper fabrics.

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