Waterborne polyurethane adhesive and preparation method thereof

Abstract

The invention discloses a waterborne polyurethane adhesive and a preparation method thereof, and belongs to the technical field of high polymer materials. The waterborne polyurethane adhesive provided by the invention comprises a main agent and a curing agent, and most of raw materials of the main agent and the curing agent are waterborne materials, such as a waterborne polyurethane dispersion, a waterborne acrylic emulsion, a waterborne EVA emulsion, a waterborne rosin resin emulsion, a waterborne terpene resin emulsion and waterborne isocyanate. Due to the water-based materials, the adhesive has the characteristics of low VOC (volatile organic compounds), zero formaldehyde and low odor. Moreover, the water-based isocyanate in the curing agent and the active hydroxyl in the main agent component can be subjected to addition polymerization reaction to form a cross-linked network polymer, so that the adhesive has relatively high cohesiveness and can meet the bonding requirement of the automotive trim.

Description

Technical Field

[0001] This application relates to the technical field of polymer materials, and particularly relates to an aqueous polyurethane adhesive and a preparation method thereof. Background Art

[0002] With the development of technology, polyurethane materials have been increasingly widely used in many fields, such as automotive interior parts. However, most current automotive interior parts, such as instrument panels and car doors, mainly use solvent-based polyurethane adhesives. Such adhesives not only contain a large amount of VOC (Volatile Organic Compounds), but also slowly release hydrogen chloride, which causes great harm to the human body over a long time. Therefore, green and pollution-free aqueous polyurethane adhesives with excellent performance have become the focus of research. Summary of the Invention

[0003] Embodiments of this application provide an aqueous polyurethane adhesive and a preparation method thereof. The aqueous polyurethane adhesive has the characteristics of low VOC, zero formaldehyde, low odor, and strong adhesiveness. The technical solution is as follows:

[0004] On the one hand, an aqueous polyurethane adhesive is provided, which includes: a main agent and a curing agent;

[0005] The mass ratio of the main agent to the curing agent is 1:0.9 - 1.1;

[0006] The main agent includes the following components by mass fraction:

[0007] 40 - 50% of an aqueous polyurethane dispersion, 15 - 30% of an aqueous acrylic emulsion, 10 - 30% of an aqueous ethylene-vinyl acetate copolymer EVA emulsion, 10 - 20% of an aqueous rosin resin emulsion, 10 - 20% of an aqueous terpene resin emulsion, 2.6 - 9% of an auxiliary agent;

[0008] The curing agent includes the following components by mass fraction:

[0009] 70 - 80% of an aqueous isocyanate, 10 - 25% of a diluent, 5 - 10% of an aqueous color paste, 0.1 - 0.5% of a catalytic coupling agent.

[0010] In a possible implementation, the aqueous polyurethane dispersion includes at least one of XP 2637, Witcobond 320, and PU502.

[0011] In another possible implementation, the aqueous acrylic emulsion includes RHOPLEX TM N-495 and PRIMAL TM at least one of 928.

[0012] In another possible implementation, the aqueous EVA emulsion includes 192 and at least one of those in EP 645.

[0013] In another possible implementation, the aqueous rosin resin emulsion is BF-125.

[0014] In another possible implementation, the aqueous terpene resin emulsion includes at least one of Foreverest TM TPR602E and F0308-X.

[0015] In another possible implementation, the auxiliary agent includes at least one of a thickener, an antifoaming agent, a wetting and leveling agent, and a bactericidal and mildew-proof agent.

[0016] In another possible implementation, if the auxiliary agent includes the thickener, the antifoaming agent, the wetting and leveling agent, and the bactericidal and mildew-proof agent, the mass fraction of the thickener is 1-5%, the mass fraction of the antifoaming agent is 0.5-1%, the mass fraction of the wetting and leveling agent is 1-2%, and the mass fraction of the bactericidal and mildew-proof agent is 0.1-1%.

[0017] In another possible implementation, the aqueous isocyanate includes at least one of diphenylmethane diisocyanate and 1,6-hexamethylene diisocyanate.

[0018] On the other hand, a preparation method of an aqueous polyurethane adhesive is provided, and the preparation method includes:

[0019] Mix the aqueous polyurethane dispersion, the aqueous EVA emulsion, and the aqueous rosin resin emulsion evenly according to the mass fractions of the components, and react at 60-80 °C for 2-4 h;

[0020] Continue to add the aqueous acrylic emulsion and react at 50-60 °C for 1-3 h;

[0021] Continue to add the aqueous terpene resin emulsion to obtain a composite emulsion;

[0022] Adjust the pH value of the composite emulsion to 7.0-8.5, and remove the solvent under reduced pressure to obtain a treated composite emulsion;

[0023] Mix the treated composite emulsion with the auxiliary agent evenly, and adjust the viscosity to less than 5000 mPa·s to obtain the main agent;

[0024] React the aqueous isocyanate at 75-85 °C for 2-3 h to obtain a prepolymer;

[0025] Add the aqueous color paste, the diluent and the catalytic coupling agent to the prepolymer, and adjust the viscosity to 500-2000 cps to obtain the curing agent;

[0026] Mix the main agent and the curing agent evenly to obtain the aqueous polyurethane adhesive.

[0027] An embodiment of the present application provides an aqueous polyurethane adhesive. This adhesive includes a main agent and a curing agent. Most of the raw materials of the main agent and the curing agent are aqueous materials, such as aqueous polyurethane dispersions, aqueous acrylic emulsions, aqueous EVA emulsions, aqueous rosin resin emulsions, aqueous terpene resin emulsions, and aqueous isocyanates. These aqueous materials make this adhesive have the characteristics of low VOC, zero formaldehyde, and low odor. Moreover, the aqueous isocyanate in the curing agent can undergo an addition polymerization reaction with the active hydroxyl groups in the main agent component to form a cross-linked network polymer, so that this adhesive has strong adhesiveness and can meet the bonding requirements of automotive interiors.

[0028] It should be understood that the above general description and the following detailed description are only exemplary and do not limit the present disclosure. Detailed Embodiments

[0029] To make the technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below.

[0030] An embodiment of the present application provides an aqueous polyurethane adhesive, which includes: a main agent and a curing agent;

[0031] The mass ratio of the main agent to the curing agent is 1:0.9-1.1;

[0032] The main agent includes the following components by mass fraction:

[0033] 40-50% of aqueous polyurethane dispersion, 15-30% of aqueous acrylic emulsion, 10-30% of aqueous ethylene-vinyl acetate copolymer (EVA) emulsion, 10-20% of aqueous rosin resin emulsion, 10-20% of aqueous terpene resin emulsion, 2.6-9% of additives;

[0034] The curing agent includes the following components by mass fraction:

[0035] 70-80% of aqueous isocyanate, 10-25% of diluent, 5-10% of aqueous color paste, 0.1-0.5% of catalytic coupling agent.

[0036] In the embodiments of the present application, the mass ratio of the main agent to the curing agent can be 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1.

[0037] The mass fraction of the aqueous polyurethane dispersion in the main agent can be 40%, 42%, 45%, 48%, 50%, the mass fraction of the aqueous acrylic emulsion can be 15%, 18%, 20%, 22%, 25%, 28%, 30%, the mass fraction of the aqueous EVA emulsion can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, the mass fraction of the aqueous rosin resin emulsion can be 10%, 12%, 15%, 18%, 20%, and the mass fraction of the aqueous terpene resin emulsion can be 10%, 12%, 15%, 18%, 20%. The mass fraction of the auxiliary agent can be 2.6%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%.

[0038] The mass fraction of the aqueous isocyanate in the curing agent can be 70%, 72%, 75%, 78%, 80%, the mass fraction of the diluent can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, the mass fraction of the aqueous color paste can be 5%, 6%, 7%, 8%, 9%, 10%, and the mass fraction of the catalytic coupling agent can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%.

[0039] The embodiment of the present application provides an aqueous polyurethane adhesive. The adhesive includes a main agent and a curing agent. Most of the raw materials of the main agent and the curing agent are aqueous materials, such as aqueous polyurethane dispersion, aqueous acrylic emulsion, aqueous EVA emulsion, aqueous rosin resin emulsion, aqueous terpene resin emulsion, and aqueous isocyanate. These aqueous materials make the adhesive have the characteristics of low VOC, zero formaldehyde, and low odor. Moreover, the aqueous isocyanate in the curing agent can undergo an addition polymerization reaction with the active hydroxyl groups in the main agent component to form a cross-linked network polymer, so that the adhesive has strong adhesiveness and can meet the bonding requirements of automotive interiors.

[0040] Compared with solvent-based polyurethane adhesives, the viscosity of the aqueous polyurethane adhesive does not change with the change of the solid content. Therefore, the cohesion and bonding strength of the aqueous polyurethane adhesive can be improved by increasing the molecular weight. Moreover, the aqueous polyurethane adhesive has good miscibility and can be blended with other emulsions with unique properties (such as acrylic emulsions, aqueous tackifying resins, etc.) to achieve effective bonding of porous materials (such as latex sponges, PVC artificial leathers, etc.) in automotive interiors. In addition, the adhesive provided by the present application is basically made of aqueous materials, and the carbon ratio can reach 99%, which can greatly reduce carbon emissions and achieve low-carbon sustainable cyclic production.

[0041] The waterborne polyurethane adhesive in the related art is an adhesive of a four-component copolymerization system, and the four-component copolymerization system mainly includes polyurethane, epoxy resin, rubber and acrylic resin. The waterborne polyurethane adhesive provided in this application is a two-component waterborne polyurethane adhesive, including a main agent and a curing agent. First, the components in the main agent will be introduced below.

[0042] In a possible implementation, the waterborne polyurethane dispersion includes at least one of XP 2637, Witcobond 320 and PU502.

[0043] In this implementation, the waterborne polyurethane dispersion is a polyurethane dispersion without emulsifier. According to the different hydrophilic groups introduced into the polyurethane molecule, it can be divided into anionic, cationic and non-ionic types. Witcobond 320 and PU502 used in this application are non-ionic, XP 2637 is ionic / non-ionic. The waterborne polyurethane dispersion used in this application gradually excludes water during the film-forming process, and its molecular chains and ionic groups are regularly arranged. There are not only electrostatic interactions and hydrogen bond forces, but also cross-linking reactions occur between molecules to form a network structure, thereby improving the adhesiveness of the waterborne polyurethane adhesive.

[0044] In a possible implementation, the waterborne acrylic emulsion includes RHOPLEX TM N-495 and PRIMAL TM at least one of 928.

[0045] In the embodiments of this application, adding an appropriate amount of waterborne acrylic emulsion can improve the water resistance, alkali resistance, weather resistance and stain resistance of the waterborne polyurethane adhesive.

[0046] In a possible implementation, the waterborne EVA emulsion includes 192 and at least one of EP 645.

[0047] In the embodiments of this application, adding an appropriate amount of waterborne EVA emulsion can enhance the flexibility, acid and alkali resistance, and ultraviolet aging resistance of the waterborne polyurethane adhesive, making the waterborne polyurethane adhesive have good miscibility, good film-forming property and good adhesiveness.

[0048] In a possible implementation, the waterborne rosin resin emulsion is BF-125.

[0049] In the embodiments of the present application, the aqueous rosin resin emulsion has good compatibility with the aqueous acrylic emulsion and the aqueous EVA emulsion, and can effectively improve the initial adhesion, holding power, shear force, adhesiveness and peel strength of the aqueous polyurethane adhesive, while maintaining good mechanical stability.

[0050] In a possible implementation, the aqueous terpene resin emulsion includes at least one of Foreverest TM TPR602E and F0308-X.

[0051] In the embodiments of the present application, the aqueous terpene resin emulsion is an environmentally friendly adhesive material made mainly of natural terpenes. Adding an appropriate amount of the aqueous terpene resin emulsion can enhance the anti-wear performance, corrosion resistance and chemical resistance of the aqueous polyurethane adhesive, and can improve the rheological properties of the aqueous polyurethane adhesive, so that the aqueous polyurethane adhesive has better fluidity. At the same time, it can also improve the film-forming performance of the aqueous polyurethane adhesive, making the surface of the aqueous polyurethane adhesive smoother and flatter.

[0052] In a possible implementation, the auxiliary agent includes at least one of a thickener, a defoamer, a wetting and leveling agent and a bactericide and mildew preventive.

[0053] In the embodiments of the present application, only the case where the auxiliary agent includes a thickener, a defoamer, a wetting and leveling agent and a bactericide and mildew preventive at the same time is taken as an example for illustration. If the auxiliary agent includes a thickener, a defoamer, a wetting and leveling agent and a bactericide and mildew preventive at the same time, the mass fraction of the thickener is 1-5%, the mass fraction of the defoamer is 0.5-1%, the mass fraction of the wetting and leveling agent is 1-2%, and the mass fraction of the bactericide and mildew preventive is 0.1-1%.

[0054] Among them, the mass fraction of the thickener can be 1%, 2%, 3%, 4%, 5%, the mass fraction of the defoamer can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, the mass fraction of the wetting and leveling agent can be 1%, 1.2%, 1.5%, 1.8%, 2%, and the mass fraction of the bactericide and mildew preventive can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%.

[0055] In a possible implementation, the thickener is RHEOBYK-H 7625VF, the defoamer includes at least one of BYK-011 and EFKA SI2008, the wetting and leveling agent is BYK333, and the bactericide and mildew preventive is K 40.

[0056] In the embodiments of the present application, the thickener is mainly used to increase the viscosity or consistency of the waterborne polyurethane adhesive, and has the characteristics of small dosage, obvious thickening, and convenient use. The defoamer is mainly used to eliminate foam, which can reduce the surface tension of water, solution, suspension, etc., prevent foam formation, or reduce or eliminate the foam of crude oil. The wetting and leveling agent is a chemical additive widely used in various coatings and adhesives, and its main function is to improve the surface properties of the waterborne polyurethane adhesive and enhance the adhesion of the waterborne polyurethane adhesive. The bactericidal and mildew-proof agent is an auxiliary agent for controlling the reproduction of microorganisms, which can increase the storage stability of the waterborne polyurethane adhesive.

[0057] The following introduces the curing agent.

[0058] The waterborne isocyanate is the main raw material of the curing agent. The conventional two-component waterborne polyurethane adhesive consists of a curing agent containing active isocyanate groups and a waterborne polyol containing active hydrogen (hydroxyl) that can react with the isocyanate groups. In this application, a large amount of active hydrogen (hydroxyl) is provided in the waterborne polyurethane dispersion, which can undergo a crosslinking reaction with the waterborne isocyanate.

[0059] During the film-forming process of the two-component waterborne polyurethane adhesive, the polyisocyanate does not undergo excessive chemical crosslinking reactions with active hydrogen (hydroxyl) or water in the early stage. It is not until most of the water has evaporated that the emulsion and the curing agent particles come into contact and are compressed. At this time, the hydroxyl groups and the remaining water in the waterborne polyurethane dispersion begin to react chemically with the -NCO groups in the curing agent in large quantities. It can be seen that the manifestation of the pot life of the two-component waterborne polyurethane adhesive may be completely different from that of the two-component solvent-based polyurethane adhesive. In many cases, the viscosity change of the two-component waterborne coating system will always remain within a range far lower than twice the initial viscosity. This means that the method of judging the pot life by the increase in viscosity, which is effective in solvent-based coatings, is not applicable in the two-component waterborne polyurethane system. In fact, we need to judge its pot life by testing the mutation points of certain properties of the paint film (such as gloss, haze, hardness, chemical resistance, etc.). Generally speaking, the reaction rate of polyisocyanate with active hydrogen (hydroxyl) is faster than that with water, but the two still have a competitive relationship. To compensate for the losses caused by the side reaction of polyisocyanate and water, generally an excessive amount of polyisocyanate is used, and the -NCO / -OH ratio is selected to be 1.5 - 3.0. Usually, the higher the -NCO / -OH ratio, the better the chemical resistance of the coating film, but the longer the drying time and the higher the cost. Generally, the -NCO / -OH ratio is controlled at about 1.5, so as to obtain the isocyanate with the best cost performance.

[0060] The waterborne isocyanate used in this application includes at least one of diphenylmethane diisocyanate (MDI) and 1,6-hexamethylene diisocyanate (HDI).

[0061] In a possible implementation, the diluent is NTX ECO Thinner.

[0062] The diluent provided in this application is a new generation of reactive epoxy resin diluent, which is halogen-free, odorless, colorless, and has strong diluting ability.

[0063] In a possible implementation, the aqueous color paste is Reactint.

[0064] Among them, the color of the aqueous color paste can be set and changed as needed, and no specific limitation is made thereto. For example, the color of the aqueous color paste is blue, red or green.

[0065] The aqueous color paste is mainly used for better identification during the spraying process, preventing the impact on the bonding performance caused by repeated spraying, and also avoiding the waste of materials.

[0066] In a possible implementation, the catalytic coupling agent is KH-602.

[0067] In the embodiments of this application, the catalytic coupling agent is mainly used to promote the reaction activity of isocyanate and active hydrogen (hydroxyl group).

[0068] The aqueous polyurethane adhesive provided in this application uses aqueous materials as raw materials for both the main agent and the curing agent. The component design takes into account the low odor, low VOC, zero formaldehyde and bonding performance of the materials. The finally obtained aqueous polyurethane adhesive has strong bonding property, low odor, low VOC and zero formaldehyde, and can be used for bonding interior parts such as automotive interior door panels, pillar trim panels, trunk carpets, coat racks, sun visors, steering wheels, etc.

[0069] The embodiments of this application also provide a preparation method of an aqueous polyurethane adhesive, and the preparation method includes:

[0070] Step 1: According to the mass fractions of the components, mix the aqueous polyurethane dispersion, aqueous EVA emulsion and aqueous rosin resin emulsion evenly, and react at 60-80 °C for 2-4 h.

[0071] The reaction temperature in Step 1 can be 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, and the reaction time can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h.

[0072] Step 2: Continuously add the aqueous acrylic emulsion and react at 50-60 °C for 1-3 h.

[0073] Add the aqueous acrylic emulsion to the reaction solution obtained in Step 1 and react at a certain temperature for a period of time.

[0074] The reaction temperature in Step 2 can be 50 °C, 52 °C, 55 °C, 58 °C, 60 °C, and the reaction time can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h.

[0075] Step 3: Continuously add the aqueous terpene resin emulsion to obtain a composite emulsion.

[0076] Add the aqueous terpene resin emulsion to the reaction solution obtained in Step 2, and after stirring evenly, obtain a composite emulsion.

[0077] Step 4: Adjust the pH value of the composite emulsion to 7.0 - 8.5, and remove the solvent under reduced pressure to obtain the treated composite emulsion.

[0078] Adjust the pH value of the composite emulsion to 7.0 - 8.5 by an acid or a base, and remove water under reduced pressure to obtain the treated composite emulsion.

[0079] Among them, the pH can be 7.0, 7.2, 7.5, 7.8, 8.0, 8.2, 8.5.

[0080] Step 5: Mix the treated composite emulsion with an auxiliary agent evenly, and adjust the viscosity to less than 5000 mPa·s to obtain the main agent.

[0081] If the auxiliary agent includes a thickener, an antifoaming agent, a wetting and leveling agent, and a bactericidal and mildew-proof agent at the same time, this step is: Mix the treated composite emulsion with the thickener, the antifoaming agent, the wetting and leveling agent, and the bactericidal and mildew-proof agent evenly, and adjust the viscosity to less than 5000 mPa·s to obtain the main agent.

[0082] It should be noted that a filler or a cosolvent can also be added during the preparation of the main agent to enhance the performance. The filler can be calcium carbonate or talcum powder, and the cosolvent can be propylene glycol.

[0083] Step 6: React the aqueous isocyanate at 75 - 85 °C for 2 - 3 h to obtain a prepolymer.

[0084] React the aqueous isocyanate at 75 - 85 °C for 2 - 3 h to generate an NCO-terminated prepolymer, among which the NCO content is 2 - 5%, for example, the NCO content is 2%, 3%, 4%, 5%.

[0085] The reaction temperature in Step 6 can be 75 °C, 80 °C, 85 °C, and the reaction time can be 2 h, 2.5 h, 3 h.

[0086] Step 7: Add an aqueous color paste, a diluent, and a catalytic coupling agent to the prepolymer, and adjust the viscosity to 500 - 2000 cps to obtain a curing agent.

[0087] The viscosity of the curing agent can be 500 cps, 600 cps, 700 cps, 800 cps, 900 cps, 1000 cps, 1100 cps, 1200 cps, 1300 cps, 1400 cps, 1500 cps, 1600 cps, 1700 cps, 1800 cps, 1900 cps, 2000 cps.

[0088] Step 8: Mix the main agent and the curing agent evenly to obtain the waterborne polyurethane adhesive.

[0089] Add the main agent and the curing agent into a high-speed disperser, and stir at a constant temperature of 30 - 40 °C through the high-speed disperser, with a stirring speed of 60 - 80 r / min and a stirring time of 8 - 10 min to obtain the waterborne polyurethane adhesive.

[0090] Among them, the stirring temperature can be 30 °C, 32 °C, 35 °C, 38 °C, 40 °C, the stirring speed can be 60 r / min, 70 r / min, 80 r / min, and the stirring time can be 8 min, 9 min, 10 min.

[0091] It should be noted that the main agent and the curing agent can be mixed evenly before using the waterborne polyurethane adhesive to avoid premature mixing and affecting the performance of the waterborne polyurethane adhesive.

[0092] In addition, when using the waterborne polyurethane adhesive, the waterborne polyurethane adhesive can be heated first to cause crosslinking and curing, and then it can be used for bonding automotive interior parts. The waterborne polyurethane adhesive provided by this application has a relatively fast thermal curing speed and is suitable for high-efficiency production.

[0093] The technical solution of this application will be described in detail through specific embodiments below.

[0094] In the following specific embodiments, operations not specified in conditions are carried out according to conventional conditions or conditions recommended by the manufacturer.

[0095] Example 1

[0096] Example 1 provides a waterborne polyurethane adhesive, which is obtained through the following preparation method:

[0097] Step 1: Mix 40% of XP 2637, 15% of 192 and 10% of BF-125 evenly, and react at 70 °C for 3 h.

[0098] Step 2: Continuously add 20% of RHOPLEX TM N-495, and react at 55 °C for 2 h.

[0099] Step 3: Continuously add 10% of Foreverest TM TPR602E to obtain a composite emulsion.

[0100] Step 4: Adjust the pH value of the composite emulsion to 7.0, and remove the solvent under reduced pressure to obtain the treated composite emulsion.

[0101] Step 5: Mix the treated composite emulsion evenly with 2% of RHEOBYK-H 7625VF, 1% of BYK-011, 1% of BYK333, and 1% of K 40, and adjust the viscosity to 4500 mPa·s to obtain the main agent.

[0102] Step 6: React 74% of HDI at 80 °C for 2.5 h to obtain a prepolymer.

[0103] Step 7: Add 5.5% of Reactint, 20% of NTX ECO Thinner, and 0.5% of KH-602 to the prepolymer, and adjust the viscosity to 1500 cps to obtain the curing agent.

[0104] Step 8: Add the main agent and the curing agent to a high-speed disperser at a mass ratio of 1:1, and stir at a constant temperature of 30 °C by the high-speed disperser. The stirring speed is 70 r / min, and the stirring time is 10 min to obtain the waterborne polyurethane adhesive.

[0105] Example 2

[0106] Example 2 provides a waterborne polyurethane adhesive, which is obtained by the following preparation method:

[0107] Step 1: Mix 45% of PU502, 10% of EP 645 and 10% of BF-125 evenly, and react at 70 °C for 3 h.

[0108] Step 2: Continuously add 20% of PRIMAL TM 928, and react at 55 °C for 2 h.

[0109] Step 3: Continuously add 10% of F0308-X to obtain a composite emulsion.

[0110] Step 4: Adjust the pH value of the composite emulsion to 7.0, and remove the solvent under reduced pressure to obtain the treated composite emulsion.

[0111] Step 5: Mix the treated composite emulsion evenly with 2% of RHEOBYK-H 7625 VF, 1% of BYK-011, 1% of BYK333, and 1% of Mix K 40 evenly and adjust the viscosity to 4500 mPa·s to obtain the main agent.

[0112] Step 6: React 70% of MDI at 80 °C for 2.5 h to obtain a prepolymer.

[0113] Step 7: Add 5.5% of Reactint, 24% of NTX ECO Thinner, and 0.5% of KH-602 to the prepolymer, and adjust the viscosity to 1500 cps to obtain the curing agent.

[0114] Step 8: Add the main agent and the curing agent to a high-speed disperser at a mass ratio of 1:1, and stir at a constant temperature of 30 °C by the high-speed disperser. The stirring speed is 70 r / min, and the stirring time is 10 min to obtain the waterborne polyurethane adhesive.

[0115] Example 3

[0116] Example 3 provides a waterborne polyurethane adhesive, which is obtained by the following preparation method:

[0117] Step 1: Mix 40% of Witcobond 320, 10% of 192 and 10% of BF-125 evenly and react at 70 °C for 3 h.

[0118] Step 2: Continuously add 25% of RHOPLEX TM N-495 and react at 55 °C for 2 h.

[0119] Step 3: Continuously add 10% of Foreverest TM TPR602E to obtain a composite emulsion.

[0120] Step 4: Adjust the pH value of the composite emulsion to 7.0 and remove the solvent under reduced pressure to obtain the treated composite emulsion.

[0121] Step 5: Mix the treated composite emulsion with 2% of RHEOBYK-H 7625VF, 1% of EFKA SI2008, 1% of BYK333, 1% of K 40 evenly and adjust the viscosity to 4500 mPa·s to obtain the main agent.

[0122] Step 6: React 72% of HDI at 80 °C for 2.5 h to obtain a prepolymer.

[0123] Step 7: Add 5.5% of Reactint, 22% of NTX ECO Thinner, and 0.5% of KH-602 to the prepolymer, and adjust the viscosity to 1500 cps to obtain the curing agent.

[0124] Step 8: Add the main agent and the curing agent into a high-speed disperser at a mass ratio of 1:1, and stir at a constant temperature of 30°C by the high-speed disperser. The stirring speed is 70 r / min, and the stirring time is 10 min to obtain the waterborne polyurethane adhesive.

[0125] The specific compositions of Examples 1 to 3 can also be seen in Table 1.

[0126] Table 1

[0127]

[0128]

[0129] The waterborne polyurethane adhesives prepared in Examples 1 to 3 of this application were respectively tested. The test results of Example 1 can be seen in Table 2, the test results of Example 2 can be seen in Table 3, and the test results of Example 3 can be seen in Table 4. Among them, the test of peel strength refers to "GB / T 2790", the test of volatile organic compounds in the parts assembly refers to "IS012219-2-2012", the test of aldehyde and ketone substances in the parts assembly refers to "IS012219-2-2012", and the test of TVOC (total volatile organic compounds) refers to "IS012219-2-2012".

[0130] Table 2

[0131]

[0132] Among them, the process of one high and low temperature alternating cycle is:

[0133]

[0134] Table 3

[0135]

[0136] Table 4

[0137]

[0138]

[0139] It can be seen from the test results in Tables 2 to 4 that: the waterborne polyurethane adhesive prepared in this application not only has the characteristics of low odor, low VOC, and zero formaldehyde, but also has strong bonding performance, which can meet the bonding requirements of automotive interior parts.

[0140] The above description is only for the convenience of those skilled in the art to understand the technical solution of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A water-based polyurethane adhesive, characterized in that: The water-based polyurethane adhesive comprises: a main agent and a curing agent; The mass ratio of the main agent to the curing agent is 1:0.9-1.1; The main agent includes the following components by mass fraction: 40-50% water-based polyurethane dispersion, 15-30% water-based acrylic emulsion, 10-30% water-based ethylene-vinyl acetate copolymer EVA emulsion, 10-20% water-based rosin resin emulsion, 10-20% water-based terpene resin emulsion, 2.6-9% additives; The curing agent includes the following components by mass fraction: 70-80% water-based isocyanate, 10-25% diluent, 5-10% water-based color paste, 0.1-0.5% catalytic coupling agent.

2. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous polyurethane dispersion comprises At least one of XP 2637, Witcobond 320 and PU502.

3. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous acrylic emulsion includes RHOPLEX TM N-495 and PRIMAL TM At least one of 928.

4. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous EVA emulsion comprises 192 and At least one of EP 645.

5. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous rosin resin emulsion is BF-125.

6. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous terpene resin emulsion includes Foreverest TM At least one of TPR602E and F0308-X.

7. The water-based polyurethane adhesive according to claim 1, characterized in that: The auxiliary agent includes at least one of a thickener, a defoamer, a wetting and leveling agent, and a bactericide and mildew preventer.

8. The water-based polyurethane adhesive according to claim 7, characterized in that: If the auxiliary agent includes the thickener, the defoamer, the wetting and leveling agent and the bactericidal and mildew-proof agent, the mass fraction of the thickener is 1-5%, the mass fraction of the defoamer is 0.5-1%, the mass fraction of the wetting and leveling agent is 1-2%, and the mass fraction of the bactericidal and mildew-proof agent is 0.1-1%.

9. The water-based polyurethane adhesive according to claim 1, characterized in that: The aqueous isocyanate includes at least one of diphenylmethane diisocyanate and hexamethylene diisocyanate.

10. A method for preparing the waterborne polyurethane adhesive according to any one of claims 1 to 9, characterized in that: The preparation method comprises: According to the mass fraction of each component, the aqueous polyurethane dispersion, the aqueous EVA emulsion and the aqueous rosin resin emulsion are uniformly mixed and reacted at 60 to 80° C. for 2 to 4 hours; Continue to add the aqueous acrylic emulsion and react at 50-60° C. for 1-3 hours; Continue to add the aqueous terpene resin emulsion to obtain a composite emulsion; The pH value of the composite emulsion is adjusted to 7.0-8.5, and the solvent is removed under reduced pressure to obtain a treated composite emulsion; The treated composite emulsion is mixed evenly with the auxiliary agent, and the viscosity is adjusted to be less than 5000 mPa·s to obtain the main agent; reacting the aqueous isocyanate at 75 to 85° C. for 2 to 3 hours to obtain a prepolymer; Adding the water-based color paste, the diluent and the catalytic coupling agent to the prepolymer and adjusting the viscosity to 500-2000 cps to obtain the curing agent; The main agent and the curing agent are mixed evenly to obtain the water-based polyurethane adhesive.

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