1. An adhesive for bonding metal and plastic is characterized in that: the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol;

wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane; the metal substrate is an aluminum alloy.

Background

Polypropylene (PP) is a colorless, odorless, nontoxic and semitransparent solid substance, is a thermoplastic synthetic resin with excellent performance, is colorless and semitransparent thermoplastic light general-purpose plastic, and has chemical resistance, heat resistance, electric insulation, high-strength mechanical performance, good high-wear-resistance processing performance and the like, so that the polypropylene is rapidly and widely developed and applied in various fields such as machinery, automobiles, electronic and electric appliances, buildings, textiles, packaging, agriculture, forestry, fishery, food industry and the like since the coming out.

With the more and more extensive application of polypropylene, the mechanical function of metal has been gradually replaced according to the high strength and high wear resistance of polypropylene, so a great amount of polypropylene and metal composite materials are also appeared, and in the use process of polypropylene, sometimes an adhesive is needed to bond the polypropylene and the metal, which has higher requirement on the performance of the adhesive.

At present, the adhesive disclosed in the market has poor bonding performance for polypropylene and metal substrates, and the polypropylene and the metal substrates are easy to be bonded, so that the situation that the polypropylene and the metal substrates are not firm and are easy to fall off is easy to occur, which brings inconvenience to people.

Disclosure of Invention

The invention aims to provide an adhesive for bonding metal and plastic and a preparation method thereof, so as to solve the problems in the background technology.

In order to solve the technical problems, the invention provides the following technical scheme:

the adhesive for bonding metal and plastic comprises the following raw materials: by weight, 15-20 parts of polyurethane formate, 18-22 parts of polyisocyanate, 10-12 parts of epoxy resin, 6-8 parts of isophorone diisocyanate, 8-10 parts of phenolic resin, 5-8 parts of silicon dioxide, 8-10 parts of dopamine hydrochloride solution, 4-6 parts of defoaming agent, 4-6 parts of toughening agent and 8-10 parts of polypropylene glycol.

In an optimized scheme, the defoaming agent is diethylene glycol monomethyl ether.

In an optimized scheme, the toughening agent is styrene butadiene rubber.

The application discloses an adhesive for bonding metal and plastic, which comprises polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, phenolic resin, silicon dioxide, dopamine hydrochloride solution, a defoaming agent, a toughening agent and the like, wherein the dopamine hydrochloride solution can undergo autopolymerization to form polydopamine, and the polydopamine has excellent bonding power and has excellent bonding power with a metal substrate and a polypropylene substrate; the system also introduces components such as urethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate and the like, wherein the components contain a large amount of active functional groups such as isocyanate groups, carbamate groups, epoxy groups and the like, and can be bonded with the metal substrate and the polypropylene substrate through chemical combination and physical action, and the components in the system are mutually synergistic, so that the prepared adhesive has excellent cohesiveness, can be widely applied to adhesion between plastics and metals, and has excellent bonding effect and higher practicability.

A preparation method of an adhesive for bonding metal and plastic comprises the following steps: taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 20-30min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 10-20min at 60-70 ℃, adding a defoaming agent and a toughening agent, and stirring for 1-2h at 50-60 ℃ to obtain the adhesive.

The use of an adhesive for bonding metal and plastic is used for bonding a metal substrate and a polypropylene substrate, and the specific use steps are as follows:

1) preparing a modified metal substrate;

a) taking a metal substrate, baking the metal substrate at the temperature of 280-300 ℃, performing shot blasting rust removal, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning, and performing vacuum drying to obtain a pretreated substrate;

b) taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in an argon and nitrogen atmosphere, wherein the target material is metal tantalum to obtain a substrate A;

c) placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of the tantalum layer, wherein the targets are respectively metal tantalum and metal silver to obtain a substrate B;

d) taking an aminosilane coupling agent and ethanol, stirring for dissolving, performing ultrasonic dispersion, adding a substrate B, soaking at 30-40 ℃, washing and drying to obtain a modified metal substrate;

2) preparing a modified polypropylene substrate;

a) taking a polypropylene substrate, and preheating the polypropylene substrate in a nitrogen environment for later use;

b) adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 10-12h, drying in vacuum, adding TMI and styrene into the nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 2-5h, washing and drying to obtain a polypropylene substrate;

3) preparing an adhesive: preparing polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol, phenolic resin, silicon dioxide, dopamine hydrochloride solution, a defoaming agent and a toughening agent to obtain an adhesive;

4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

The optimized scheme comprises the following specific using steps:

1) preparation of modified metal substrate:

a) taking a metal substrate, baking at the temperature of 280-300 ℃ for 15-25min, performing shot blasting rust removal, wherein the current is 8-14A and the processing time is 10-25min, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 15-25min, and performing vacuum drying to obtain a pretreated substrate;

b) taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in the atmosphere of argon and nitrogen, wherein the target is metal tantalum, the working pressure is 0.8-0.9Pa, the sputtering power is 200-300W, and the thickness of the tantalum layer is 80-100nm to obtain a substrate A;

c) placing the substrate A in an argon and nitrogen atmosphere, sputtering a silver coating on the upper surface of the tantalum layer, wherein the targets are respectively metal tantalum and metal silver, the working pressure is 0.8-0.9Pa, the sputtering power of the metal silver palladium is 140-150W, and the sputtering power of the metal tantalum target is 20-26W, so as to obtain a substrate B;

d) taking an aminosilane coupling agent and ethanol, stirring for dissolving, performing ultrasonic dispersion, adding a substrate B, soaking for 2-3h at 30-40 ℃, washing and drying to obtain a modified metal substrate;

2) preparation of modified polypropylene substrate:

a) taking a polypropylene substrate, and preheating the polypropylene substrate in a nitrogen environment for later use;

b) adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 10-12h, drying in vacuum, adding TMI and styrene into the nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 2-5h, washing and drying to obtain a polypropylene substrate;

3) preparing an adhesive: preparing polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol, phenolic resin, silicon dioxide, dopamine hydrochloride solution, a defoaming agent and a toughening agent to obtain an adhesive;

4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product. The hot-pressing compounding temperature is 100-110 ℃.

In an optimized scheme, in the step 1), the aminosilane coupling agent is any one or a mixture of (3-aminopropyl) triethoxysilane, (3-aminopropyl) trimethoxysilane and aminopropylmethyldimethoxysilane.

In an optimized scheme, in the step a) of the step 2), the preheating temperature is 25-28 ℃, and the preheating time is 10-20 min.

In an optimized scheme, in the step 4), the drying temperature is 50-60 ℃.

The optimized proposal is that in the step d) of the step 1), the ultrasonic dispersion time is 8-10min

Compared with the prior art, the invention has the following beneficial effects:

the application discloses an adhesive for bonding metal and plastic and a preparation method thereof, the prepared adhesive can be used independently and widely applied to metal and plastic adhesion, and the invention also discloses an optimal adhesive using method, when the adhesive is used for bonding a metal substrate and a polypropylene substrate, the metal substrate and the polypropylene substrate are modified to further improve the bonding performance between the metal and the polypropylene, and the specific processing method comprises the following steps:

this application is toasted through high temperature at first, thoroughly carbonizes metal substrate surface and inside grease impurity, eliminates the grease, throws the ball rust cleaning to metal substrate again, can thoroughly clear away the impurity and the oxide on metal substrate surface, washes through acetone, absolute ethyl alcohol and deionized water afterwards, washs substrate surface, obtains the preliminary treatment base member after the washing drying.

In the pretreatment process, because a large number of cracks are easy to appear on the surface of the metal substrate after shot blasting rust removal, the cracks do not affect the normal use of the metal substrate, but a large acting force is generated after the metal substrate is mutually bonded with the plastic through the adhesive, thereby reducing the adhesive effect of the adhesive, and in order to reduce the influence caused by cracks, the application firstly plates a tantalum layer on the pretreated substrate by adopting magnetron sputtering, the tantalum layer is made of tantalum nitride, the tantalum nitride has excellent wear resistance and corrosion resistance and higher hardness, the strength of the metal substrate can be effectively improved, the metal substrate can be protected to improve the corrosion resistance, meanwhile, the cracks can be repaired after the tantalum carbide layer is plated on the surface of the metal substrate, so that the influence of the cracks on the adhesive can be reduced, the acting force of the adhesive is reduced during subsequent treatment, and the excellent viscosity is kept.

Meanwhile, a silver layer needs to be plated on the surface of the metal substrate in subsequent treatment, in order to avoid the influence of the tantalum layer, the silver layer is formed by jointly sputtering silver and tan nitride when the silver layer is sputtered, the silver layer is a composite layer formed by jointly sputtering silver and tan nitride, and at the moment, the tantalum layer and the silver layer have better transition performance.

Then, performing amination modification on the metal substrate after the silver layer is sputtered by using an aminosilane coupling agent, wherein the surface of the prepared modified metal substrate contains a large amount of amino groups, and the amino groups can be introduced to react and bond with isocyanate in the adhesive so as to further improve the adhesive property of the adhesive; meanwhile, due to the increase of active groups, the existence of epoxy groups and carbamate groups can realize the adhesion to metal, the chemical combination and physical bonding effects between the adhesive and the metal substrate are greatly increased, and the adhesion effect is excellent.

The method is characterized in that a polypropylene substrate is modified, preheated firstly, and then grafted with TMI and styrene on the polypropylene substrate through a boron-oxygen initiation system to realize the isocyanate surface functionalization of the polypropylene substrate, so that the bottom surface of the modified polypropylene substrate contains a large amount of isocyanate groups, and the adhesive also contains a large amount of polyurethane, polyisocyanate and other components.

The dopamine hydrochloride solution is added, so that polydopamine can be formed by self-polymerization, the polydopamine has excellent cohesiveness, and has excellent cohesive force with metal and plastic, meanwhile, components such as polyisocyanate and isophorone diisocyanate are introduced into adhesive bonding, a large number of isocyanate groups are contained in the system and can react with amino groups in the dopamine to generate carbamido groups, so that the crosslinking degree of each component of the adhesive is further improved, and the amino groups in the dopamine can also react with the isocyanate groups on the surface of the modified polypropylene base to enhance the cohesive force between the adhesive and the modified polypropylene base.

The invention discloses an adhesive for bonding metal and plastic and a preparation method thereof, the prepared adhesive not only has good bonding force to metal, but also has good bonding force to plastic, and meanwhile, the adhesive is matched with a metal substrate and a plastic substrate to carry out surface modification treatment when in use, so that the bonding property between the treated metal and plastic is greatly improved, the service life is long, the condition of adhesive falling is not easy to occur, and the practicability is higher.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 280 ℃ for 25min, performing shot blasting to remove rust, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 15min, and performing vacuum drying to obtain a pretreated substrate, wherein the current is 8A and the treatment time is 25 min;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in the atmosphere of argon and nitrogen, wherein the target material is metal tantalum, the working pressure is 0.8Pa, the sputtering power is 300W, and the thickness of the tantalum layer is 80nm to obtain a substrate A;

placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of a tantalum layer, wherein targets are respectively metal tantalum and metal silver, the working pressure is 0.8Pa, the sputtering power of the metal silver palladium is 150W, and the sputtering power of a metal tantalum target is 26W, so as to obtain a substrate B;

taking an aminosilane coupling agent and ethanol, stirring and dissolving, performing ultrasonic dispersion for 8min, adding a substrate B, soaking for 3h at 30 ℃, washing and drying to obtain a modified metal substrate;

(2) preparation of modified polypropylene substrate:

preheating a polypropylene substrate in a nitrogen environment at 25 ℃ for 20min for later use;

adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 10 hours, carrying out vacuum drying, adding TMI and styrene into the mixture under a nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 2 hours, washing and drying to obtain a polypropylene substrate;

(3) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 20min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 20min at 60 ℃, adding a defoaming agent and a toughening agent, and stirring for 2h at 50 ℃ to obtain an adhesive;

(4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 50 ℃ for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying at 50 ℃ for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 15 parts of polyurethane formate, 18 parts of polyisocyanate, 10 parts of epoxy resin, 6 parts of isophorone diisocyanate, 8 parts of phenolic resin, 5 parts of silicon dioxide, 8 parts of dopamine hydrochloride solution, 4 parts of defoaming agent, 4 parts of toughening agent and 8 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) triethoxysilane. The metal substrate is an aluminum alloy.

Example 2:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 290 ℃ for 20min, performing shot blasting rust removal, wherein the current is 12A and the treatment time is 20min, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 20min, and performing vacuum drying to obtain a pretreated substrate;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in an argon and nitrogen atmosphere, wherein a target material is metal tantalum, the working pressure is 0.8Pa, the sputtering power is 250W, and the thickness of the tantalum layer is 90nm to obtain a substrate A;

placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of a tantalum layer, wherein targets are respectively metal tantalum and metal silver, the working pressure is 0.8Pa, the sputtering power of the metal silver palladium is 145W, and the sputtering power of a metal tantalum target is 24W, so as to obtain a substrate B;

taking an aminosilane coupling agent and ethanol, stirring and dissolving, performing ultrasonic dispersion for 9min, adding a substrate B, soaking for 2.5h at 35 ℃, washing and drying to obtain a modified metal substrate;

(2) preparation of modified polypropylene substrate:

preheating a polypropylene substrate in a nitrogen environment at 27 ℃ for 15min for later use;

adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 11h, drying in vacuum, adding TMI and styrene into the nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 3.5h, washing and drying to obtain a polypropylene substrate;

(3) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 25min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 15min at 65 ℃, adding a defoaming agent and a toughening agent, and stirring for 1.5h at 55 ℃ to obtain an adhesive;

(4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 55 ℃ for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying at 55 ℃ for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane. The metal substrate is an aluminum alloy.

Example 3:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 300 ℃ for 15min, performing shot blasting to remove rust, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 25min, and performing vacuum drying to obtain a pretreated substrate, wherein the current is 14A and the treatment time is 10 min;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in an argon and nitrogen atmosphere, wherein a target material is metal tantalum, the working pressure is 0.9Pa, the sputtering power is 200W, and the thickness of the tantalum layer is 100nm to obtain a substrate A;

placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of a tantalum layer, wherein targets are respectively metal tantalum and metal silver, the working pressure is 0.9Pa, the sputtering power of the metal silver palladium is 140W, and the sputtering power of a metal tantalum target is 20W, so as to obtain a substrate B;

taking an aminosilane coupling agent and ethanol, stirring and dissolving, performing ultrasonic dispersion for 10min, adding a substrate B, soaking for 2h at 40 ℃, washing and drying to obtain a modified metal substrate;

(2) preparation of modified polypropylene substrate:

preheating a polypropylene substrate in a nitrogen environment at 28 ℃ for 10min for later use;

adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 12 hours, carrying out vacuum drying, adding TMI and styrene into the mixture under a nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 5 hours, washing and drying to obtain a polypropylene substrate;

(3) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 30min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 10min at 70 ℃, adding a defoaming agent and a toughening agent, and stirring for 1h at 60 ℃ to obtain an adhesive;

(4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 60 ℃ for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying at 60 ℃ for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 20 parts of polyurethane formate, 22 parts of polyisocyanate, 12 parts of epoxy resin, 8 parts of isophorone diisocyanate, 10 parts of phenolic resin, 8 parts of silicon dioxide, 10 parts of dopamine hydrochloride solution, 6 parts of defoaming agent, 6 parts of toughening agent and 10 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is aminopropyl methyl dimethoxy silane. The metal substrate is an aluminum alloy.

Comparative example 1: comparative example 1 a control was made according to example 2, wherein the adhesive of comparative example 1 was not supplemented with dopamine hydrochloride solution, and the remaining process parameters and component content were identical to those of example 2.

Comparative example 2: comparative example 2a control was made according to example 2, wherein the adhesive of comparative example 1 had no polyisocyanate and no isophorone diisocyanate added, and the remaining process parameters and component content were identical to those of example 2.

Comparative example 3:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 290 ℃ for 20min, performing shot blasting rust removal, wherein the current is 12A and the treatment time is 20min, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 20min, and performing vacuum drying to obtain a pretreated substrate;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in an argon and nitrogen atmosphere, wherein a target material is metal tantalum, the working pressure is 0.8Pa, the sputtering power is 250W, and the thickness of the tantalum layer is 90nm to obtain a substrate A;

placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of a tantalum layer, wherein targets are respectively metal tantalum and metal silver, the working pressure is 0.8Pa, the sputtering power of the metal silver palladium is 145W, and the sputtering power of a metal tantalum target is 24W, so as to obtain a modified metal substrate;

(2) preparation of modified polypropylene substrate:

preheating a polypropylene substrate in a nitrogen environment at 27 ℃ for 15min for later use;

adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 11h, drying in vacuum, adding TMI and styrene into the nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 3.5h, washing and drying to obtain a polypropylene substrate;

(3) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 25min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 15min at 65 ℃, adding a defoaming agent and a toughening agent, and stirring for 1.5h at 55 ℃ to obtain an adhesive;

(4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 55 ℃ for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying at 55 ℃ for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane. The metal substrate is an aluminum alloy.

Comparative example 4:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 290 ℃ for 20min, performing shot blasting rust removal, wherein the current is 12A and the treatment time is 20min, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 20min, and performing vacuum drying to obtain a pretreated substrate;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering a silver coating layer under the atmosphere of argon and nitrogen, wherein targets are respectively metal tantalum and metal silver, the working air pressure is 0.8Pa, the sputtering power of the metal silver palladium is 145W, and the sputtering power of a metal tantalum target is 24W, so as to obtain a substrate B;

taking an aminosilane coupling agent and ethanol, stirring and dissolving, performing ultrasonic dispersion for 9min, adding a substrate B, soaking for 2.5h at 35 ℃, washing and drying to obtain a modified metal substrate;

(2) preparation of modified polypropylene substrate:

preheating a polypropylene substrate in a nitrogen environment at 27 ℃ for 15min for later use;

adding a mixed solution of triethylboron and tetrahydrofuran into a polypropylene substrate, stirring and reacting for 11h, drying in vacuum, adding TMI and styrene into the nitrogen environment, stopping conveying nitrogen, inputting air, stirring and reacting for 3.5h, washing and drying to obtain a polypropylene substrate;

(3) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 25min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 15min at 65 ℃, adding a defoaming agent and a toughening agent, and stirring for 1.5h at 55 ℃ to obtain an adhesive;

(4) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 55 ℃ for later use; coating a layer of adhesive on the modified surface of the modified polypropylene substrate, and drying at 55 ℃ for later use; and overlapping the modified metal base coat coating surface and the modified polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane. The metal substrate is an aluminum alloy.

Comparative example 5:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparation of modified metal substrate:

taking a metal substrate, baking at 290 ℃ for 20min, performing shot blasting rust removal, wherein the current is 12A and the treatment time is 20min, sequentially placing the metal substrate in acetone, ethanol and deionized water for ultrasonic cleaning for 20min, and performing vacuum drying to obtain a pretreated substrate;

taking a pretreatment substrate, placing the pretreatment substrate in a sputtering cavity, and sputtering and plating a tantalum layer in an argon and nitrogen atmosphere, wherein a target material is metal tantalum, the working pressure is 0.8Pa, the sputtering power is 250W, and the thickness of the tantalum layer is 90nm to obtain a substrate A;

placing the substrate A in argon and nitrogen atmosphere, and sputtering a silver coating on the upper surface of a tantalum layer, wherein targets are respectively metal tantalum and metal silver, the working pressure is 0.8Pa, the sputtering power of the metal silver palladium is 145W, and the sputtering power of a metal tantalum target is 24W, so as to obtain a substrate B;

taking an aminosilane coupling agent and ethanol, stirring and dissolving, performing ultrasonic dispersion for 9min, adding a substrate B, soaking for 2.5h at 35 ℃, washing and drying to obtain a modified metal substrate;

(2) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 25min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 15min at 65 ℃, adding a defoaming agent and a toughening agent, and stirring for 1.5h at 55 ℃ to obtain an adhesive;

(3) coating a layer of adhesive on one surface of a modified metal substrate subjected to modification of an aminosilane coupling agent, and drying at 55 ℃ for later use; coating a layer of adhesive on one surface of a common polypropylene substrate, and drying at 55 ℃ for later use; and overlapping the modified metal base coat coating surface and the common polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane. The metal substrate is an aluminum alloy.

Comparative example 6:

the application of the adhesive for bonding metal and plastic comprises the following specific application steps:

(1) preparing an adhesive:

taking polyurethane formate, polyisocyanate, epoxy resin, isophorone diisocyanate, polypropylene glycol and phenolic resin, stirring and mixing for 25min, adding silicon dioxide and dopamine hydrochloride solution, stirring for 15min at 65 ℃, adding a defoaming agent and a toughening agent, and stirring for 1.5h at 55 ℃ to obtain an adhesive;

(4) taking a metal substrate, coating a layer of adhesive on one surface of the metal substrate, and drying at 55 ℃ for later use; coating a layer of adhesive on one surface of a polypropylene substrate, and drying at 55 ℃ for later use; and overlapping the metal base coat coating surface and the polypropylene base coat coating surface, and performing hot-pressing compounding to obtain a finished product.

In this embodiment, the adhesive comprises the following raw materials: by weight, 18 parts of polyurethane formate, 20 parts of polyisocyanate, 11 parts of epoxy resin, 7 parts of isophorone diisocyanate, 9 parts of phenolic resin, 6 parts of silicon dioxide, 9 parts of dopamine hydrochloride solution, 5 parts of defoaming agent, 5 parts of toughening agent and 9 parts of polypropylene glycol.

Wherein the defoaming agent is diethylene glycol monomethyl ether; the toughening agent is styrene butadiene rubber; the amino silane coupling agent is (3-aminopropyl) trimethoxy silane. The metal substrate is an aluminum alloy.

And (3) detection test:

the samples prepared in examples 1-3 and comparative examples 1-6 were tested according to GB/T7122-1996 "determination of peel strength of high strength adhesive", and the specific test results are as follows:

item	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2
						Peel strength KN/m	7.08	7.24	7.12	6.73	6.47
	Comparative example 3	Comparative example 4	Comparative example 5	Comparative example 6
						Peel strength KN/m	5.89	6.88	5.67	4.32

Examples 1-3 are samples prepared according to the disclosed technical scheme, comparative examples 1-5 are compared with example 2, and a control test setup is performed, having:

comparative example 1 a control was made according to example 2, wherein the adhesive of comparative example 1 was not supplemented with dopamine hydrochloride solution, and the remaining process parameters and component content were identical to those of example 2.

Comparative example 2a control was made according to example 2, wherein the adhesive of comparative example 1 had no polyisocyanate and no isophorone diisocyanate added, and the remaining process parameters and component content were identical to those of example 2.

Comparative example 3 example 2 was used as a control, wherein the metal substrate in comparative example 3 was not subjected to an amination modification and the remaining process parameters and component contents were in accordance with example 2.

Comparative example 4 example 2 was used as a control, wherein the metal substrate in comparative example 4 was not subjected to tantalum layer preparation, and the remaining step parameters and component contents were in accordance with example 2.

Comparative example 5: comparative example 5 example 2 was used as a control, wherein the polypropylene substrate of comparative example 5 was a conventional polypropylene, and the remaining process parameters and component contents were the same as those of example 2.

Comparative example 6 example 2 was used as a control, wherein comparative example 6 used a conventional polypropylene substrate and a conventional aluminum alloy substrate, and the remaining process parameters and component contents were the same as those of example 2.

And (4) conclusion: the adhesive prepared by the invention has good binding force to metal and plastic, and also has good binding force to plastic, and meanwhile, when in use, the adhesive is matched with the metal substrate and the plastic substrate for surface modification treatment, so that the bonding property between the treated metal and plastic is greatly improved, the service life is long, the adhesive is not easy to fall off, and the practicability is higher.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.