CN111620984A

CN111620984A - Modified polyurethane resin and preparation method thereof, water-based paint and coating product

Info

Publication number: CN111620984A
Application number: CN202010535112.2A
Authority: CN
Inventors: 曹扬锋; 杨鹏飞; 张�杰; 黄鹂; 胡启明; 董军胜
Original assignee: Hunan Kansai Automotive Coatings Co ltd
Current assignee: Hunan Kansai Automotive Coatings Co ltd
Priority date: 2020-06-12
Filing date: 2020-06-12
Publication date: 2020-09-04
Anticipated expiration: 2040-06-12
Also published as: CN111620984B

Abstract

The invention provides a modified polyurethane resin, a preparation method thereof, a water-based paint and a film coating product. The modified polyurethane resin raw material comprises a polyisocyanate compound, a polycarbonate diol compound, a diol compound containing acidic groups, a polyethylene glycol acrylate compound, an acrylate monomer, a catalyst, an initiator, a neutralizer, an organic solvent and water, wherein the acrylate monomer and the polyethylene glycol acrylate compound in a specific ratio are introduced into polyurethane resin under the action of the initiator, so that the modified polyurethane has excellent hydration stability and water compatibility; the polyethylene glycol acrylate structure can form an intramolecular hydrogen bond and further form a hydrogen bond with a hydrophilic solvent, so that the storage stability of the modified polyurethane is further improved; when the modified polyurethane is applied to preparing the coating, the storage stability of the coating is high, the excellent anti-mixing layer performance can be kept, and the formed coating is smooth and has good flatness.

Description

Modified polyurethane resin and preparation method thereof, water-based paint and coating product

Technical Field

The invention relates to the technical field of water-based paint, in particular to modified polyurethane resin and a preparation method thereof, water-based paint and a paint film product.

Background

The automobile industry is more and more important as the pillar industry of national economy, the automobile coating industry is rapidly developed, but the toxic solvent (VOC) with strong volatility generated in the automobile production and coating process brings serious environmental pollution problems, so that the water-based resin taking water as a solvent is the focus of attention.

In the current automobile coating process, the automobile clear coat layer gradually develops towards high solid content, and the intermediate coat layer and the colored coat layer in the clear coat layer develop towards water solubility. At present, the coating technology which meets the requirement of environmental protection and can save energy is to perform wet spraying and wet spraying coating on a water-based middle coating, a water-based colored paint layer and a clear paint layer of an automobile and then bake the mixture once again to form a film, which is called as a water-based 3wet 3C1B coating process for short. The waterborne 3wet 3C1B coating process further reduces the pre-baking time of the waterborne intermediate coat, thereby shortening the construction time and reducing the construction energy consumption. However, the 3C1B coating process of the water-based 3wet sets higher requirements on the film forming capability and stability of the coating resin, the stability of the coating resin is not high, and a mixed layer can be caused, so that the leveling coefficient L/S value of the coating film is increased, the glossiness is reduced, and even the coating film is subjected to light failure.

The waterborne polyurethane gradually becomes an important direction for developing waterborne resin due to the advantages of safety, reliability, good compatibility and the like, however, the traditional waterborne polyurethane has the problem of poor compatibility, a mixed layer can appear when the waterborne 3wet 3C1B coating process is carried out, and the problem of poor storage stability of the acrylic modified polyurethane exists.

Therefore, the design and development of the acrylic modified polyurethane resin with high stability and an anti-mixing layer are of great significance.

Disclosure of Invention

Based on the above, the invention provides a modified polyurethane resin with high storage stability and a preparation method thereof, and further provides a water-based paint and a coating product.

The technical scheme of the invention is as follows.

The invention provides a modified polyurethane resin, which comprises the following raw materials in percentage by weight: 4-8% of polyisocyanate compound, 8-10% of polycarbonate diol compound, 0.2-1.0% of diol compound containing acidic groups, 0.5-10% of polyethylene glycol acrylate compound, 7-31% of acrylate monomer, 0.01-0.05% of catalyst, 0.05-0.5% of initiator, 1-2% of neutralizer, 10-18% of organic solvent and 44.0-54.0% of water.

In some embodiments, the modified polyurethane resin is prepared from the following raw materials in percentage by weight: 5-8% of polyisocyanate compound, 8-10% of polycarbonate diol compound, 0.2-1.0% of diol compound containing acidic groups, 4-10% of polyethylene glycol acrylate compound, 7-25% of acrylate monomer, 0.01-0.05% of catalyst, 0.05-0.5% of initiator, 1.2-1.7% of neutralizer, 10-18% of organic solvent and 44.0-54.0% of water.

In some of these embodiments, the polyethylene glycol acrylate compound has a structure according to formula (i):

wherein R1 is selected from any one of alkyl with 1-4 carbon atoms; r2 is selected from methyl or hydrogen atom, and n is selected from an integer of 1-500.

In some embodiments, the solid content of the modified polyurethane resin is 35 wt% to 45 wt%, the viscosity is 10mpa · s to 500mpa · s, the pH value is 6.0 to 8.0, the weight-average molecular weight is 60000 to 150000, and the acid value is 10mgKOH/g to 40 mgKOH/g.

In some of the embodiments, the polycarbonate diol compound is selected from polycarbonate diols with the weight average molecular weight of 500-4000; the polyisocyanate compound is at least one selected from the group consisting of alicyclic diisocyanate and aromatic diisocyanate.

In some of these embodiments, the acidic group in the acidic group-containing diol compound is a carboxyl group.

In some of these embodiments, the catalyst is an organometallic catalyst; the initiator is selected from a peroxy compound initiator or an azo compound initiator; the neutralizing agent is selected from small molecule amine compounds.

In some of these embodiments, the acrylate monomer is selected from at least one of isobornyl methacrylate, isobornyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, styrene, butyl acrylate, butyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, isooctyl acrylate, isooctyl methacrylate, phosphate acrylate, phosphate methacrylate, acrylic acid, and methacrylic acid.

The invention also provides a preparation method of the modified polyurethane resin, which comprises the following steps:

providing the following raw materials in percentage by weight: 4.2 to 7.6 percent of polyisocyanate compound, 8 to 10 percent of polycarbonate diol compound, 0.2 to 1.0 percent of diol compound containing acidic groups, 0.5 to 10 percent of polyethylene glycol acrylate compound, 7.45 to 30.84 percent of acrylate monomer, 0.01 to 0.05 percent of catalyst, 0.05 to 0.5 percent of initiator, 1.2 to 1.7 percent of neutralizer, 10 to 18 percent of organic solvent and 44.0 to 54.0 percent of water;

mixing the polyisocyanate compound, the polycarbonate diol compound and part of the organic solvent, and carrying out prepolymerization reaction to obtain a prepolymer;

mixing the prepolymer and the catalyst, reacting in a first stage, adding the dihydric alcohol compound containing the acidic group and part of the acrylate monomer, and reacting in a second stage to obtain a polyurethane prepolymer;

and (2) simultaneously dripping the polyethylene glycol acrylate compound, the rest of the acrylate monomer and the initiator into the mixture of the polyurethane prepolymer and the rest of the organic solvent, adding a neutralizer after the third-stage reaction, adding the water after the neutralization reaction, and emulsifying to obtain the modified polyurethane resin.

In some of these embodiments, the conditions of the first stage reaction are: reacting for 1-4 h at 70-90 ℃; and/or

The conditions of the second stage reaction are as follows: reacting for 2-4 h at 70-100 ℃; and/or

The conditions of the third-stage reaction are as follows: reacting for 1-3 h at 70-100 ℃.

The invention also provides the application of the modified polyurethane resin or the aqueous polyurethane resin prepared by the preparation method in preparing the coating.

The invention also provides a water-based paint which contains the modified polyurethane resin or the water-based polyurethane resin prepared by the preparation method.

The invention further provides a coating film product, which contains a coating film formed by the water-based paint.

Advantageous effects

1. The raw materials of the modified polyurethane resin comprise a polyisocyanate compound, a polycarbonate diol compound, a diol compound containing acidic groups, a polyethylene glycol acrylate compound, an acrylate monomer, a catalyst, an initiator, a neutralizer, an organic solvent and water; the polyurethane resin is formed by isocyanate compound and polycarbonate diol under the action of catalyst, and acrylate monomer and polyethylene glycol acrylate compound with specific proportion are introduced into the polyurethane resin under the action of initiator, so that the polyurethane resin has a structure of hydrophilic chain segment, and the structure has excellent hydration stability and water compatibility; and the modified polyurethane molecule can form intramolecular hydrogen bond with the polyethylene glycol acrylate structure in water and further form hydrogen bond with a hydrophilic solvent, so that the storage stability of the modified polyurethane is further improved.

2. In the preparation method of the modified polyurethane resin, firstly, a high molecular weight polyurethane prepolymer is formed by a polyisocyanate compound, a polycarbonate diol compound, a diol compound containing an acidic group and a part of acrylate monomers in specific parts by mass under the action of a catalyst, then the polyurethane prepolymer, a polyethylene glycol acrylate compound and the rest of acrylate monomers react under the action of an initiator and are neutralized by a neutralizer, and the modified polyurethane resin with high stability is obtained.

3. The coating comprises the modified polyurethane resin, the storage stability of the coating can be improved, the modified polyurethane resin can be uniformly dispersed in an aqueous solvent, and the coating can be prevented from generating aggregates and mixed layers in the storage, construction and processes, so that the formed coating is smooth and has good flatness.

Detailed Description

In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The term "acrylate monomer" refers to a monomer for preparing acrylic resin, mainly acrylic acid, acrylic ester and homologues thereof, and also includes a monomer commonly used for preparing acrylic copolymer resin, such as styrene for preparing styrene acrylate copolymer, and the like.

One embodiment of the invention provides a modified polyurethane resin, which comprises the following raw materials in percentage by weight: 4.2 to 7.6 percent of polyisocyanate compound, 8 to 10 percent of polycarbonate diol compound, 0.2 to 1.0 percent of diol compound containing acid groups, 0.5 to 10 percent of polyethylene glycol acrylate compound, 7.45 to 30.84 percent of acrylate monomer, 0.01 to 0.05 percent of catalyst, 0.05 to 0.5 percent of initiator, 1.2 to 1.7 percent of neutralizer, 10 to 18 percent of organic solvent and 44.0 to 54.0 percent of water.

In the modified polyurethane resin, a polyurethane resin is formed by a polyisocyanate compound and polycarbonate diol under the action of a catalyst, and an acrylate monomer and a polyethylene glycol acrylate compound in a specific ratio are introduced into the polyurethane resin under the action of an initiator, so that the polyurethane resin has a hydrophilic chain segment structure which has excellent hydration stability and water compatibility; and the modified polyurethane molecule can form intramolecular hydrogen bond with the polyethylene glycol acrylate structure in water and further form hydrogen bond with a hydrophilic solvent, so that the storage stability of the modified polyurethane is further improved.

Preferably, in some embodiments, the raw materials for preparing the modified polyurethane resin comprise, by weight: 5-8% of polyisocyanate compound, 8-10% of polycarbonate diol compound, 0.2-1.0% of diol compound containing acidic groups, 4-10% of polyethylene glycol acrylate compound, 7-25% of acrylate monomer, 0.01-0.05% of catalyst, 0.05-0.5% of initiator, 1.2-1.7% of neutralizer, 10-18% of organic solvent and 44.0-54.0% of water.

In some of these embodiments, the polyethylene glycol acrylate compound has the structure shown in formula (I):

wherein R is₁Any one selected from alkyl with 1-4 carbon atoms; r₂Is selected from methyl or hydrogen atoms, and n is an integer of 1-500. Preferably, n is an integer of 4 to 200.

The polyethylene glycol acrylate structure in the polyethylene glycol acrylate compound can form intramolecular hydrogen bonds and further form hydrogen bonds with a hydrophilic solvent, so that the storage stability of the modified polyurethane resin is further improved.

In some embodiments, the modified polyurethane resin has a solid content of 35 wt% to 45 wt%, a viscosity of 10mpa · s to 500mpa · s, a pH of 6.0 to 8.0, a weight-average molecular weight of 60000 to 150000, and an acid value of 10mgKOH/g to 40 mgKOH/g.

In some embodiments, the polycarbonate diol compound is selected from polycarbonate diols with a weight average molecular weight of 500-4000; the polyisocyanate compound is at least one selected from the group consisting of alicyclic diisocyanate and aromatic diisocyanate.

The alicyclic diisocyanate and the aromatic diisocyanate have good yellowing resistance, and the weather resistance of the modified polyurethane resin can be improved.

Preferably, the polyisocyanate compound is an alicyclic diisocyanate; further, the alicyclic diisocyanate is selected from at least one of isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate.

Preferably, the polycarbonate diol is an aliphatic polycarbonate diol having a weight average molecular weight of 1000 to 3000.

The polyurethane prepared by the aliphatic polycarbonate diol has good crystallinity, thereby being beneficial to film formation.

Further, the polycarbonate diol is preferably an aliphatic polycarbonate diol having a weight average molecular weight of 2000 to 3000.

In some embodiments, the acid group in the above diol compound containing an acid group is a carboxyl group.

And (2) taking the diol compound containing the acid group as a chain extender, and further carrying out chain extension on the polyurethane resin under the action of a catalyst to obtain the modified polyurethane resin with high molecular weight.

In some embodiments, the polyol compound containing an acidic group is selected from dimethylolpropionic acid and/or dimethylolbutyric acid.

In some of these embodiments, the catalyst is an organometallic catalyst, and the initiator is selected from a peroxy compound initiator or an azo compound initiator; the neutralizing agent is selected from small molecule amine compounds.

Under the action of a catalyst, a polyisocyanate compound and polycarbonate diol are polymerized to obtain polyurethane molecules, and meanwhile, diol compounds containing acidic groups and partial acrylate monomers react with the residual NCO groups on the isocyanate compound, so that the polyurethane molecules are subjected to chain extension and end capping to obtain a high-molecular-weight polyurethane prepolymer; and the acid groups in the diol compound containing the acid groups are hydrophilic groups, so that the dispersibility of the polyurethane in water can be further improved.

In some of these embodiments, the catalyst may be dibutyltin dilaurate.

Under the action of an initiator, a polyethylene glycol acrylate compound and an acrylate monomer are introduced into unsaturated polyurethane resin through polymerization reaction, so that the water-based resin with high storage stability and good anti-mixing layer property is obtained.

In some of these embodiments, the initiator is selected from at least one of azobisisobutyronitrile, azobiscycloheptonitrile, dibenzoyl peroxide, dicumyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, di-t-amyl peroxide, t-butyl cumyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxybenzoate, t-butyl peroxyt-valerate, and 1, 1-di-t-butyl peroxycyclohexane.

The neutralizing agent can react with acid groups in the modified polyurethane resin to form salt, so that the resin with the nonionic hydrophilic chain segment is obtained, and the dispersibility of the resin in water is improved, and the stability of the resin is improved.

In some of these embodiments, the neutralizing agent is selected from at least one of triethylamine, methyl monoethanolamine, 2-amino-2-methyl-1-propanol, triethanolamine, diethanolamine, N-dimethylethanolamine and aqueous ammonia. Further, the mole number of the neutralizing agent is 80-95% of the total mole number of the polyol compound containing the acid group and the acrylate monomer.

In some of the embodiments, the above-mentioned acrylate monomer is selected from at least one of isobornyl methacrylate, isobornyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, styrene, butyl acrylate, butyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, isooctyl acrylate, isooctyl methacrylate, phosphate acrylate, phosphate methacrylate, acrylic acid, and methacrylic acid.

The acrylate monomer and the double bonds in the polyurethane prepolymer are subjected to free radical polymerization under the action of the initiator, so that the acrylate monomer is introduced into polyurethane molecules, the polyurethane is modified, and the weather resistance and the hydration stability of the polyurethane are improved.

In some of these embodiments, the organic solvent is selected from water-miscible solvents. Further, the organic solvent is an alcohol organic solvent or a ketone organic solvent.

In some of these embodiments, the alcoholic organic solvent is selected from at least one of propylene glycol monobutyl ether, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol methyl ether, propylene glycol propyl ether, propylene glycol butyl ether, dipropylene glycol methyl ether, dipropylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, tripropylene glycol monomethyl ether, and derivatives thereof; the ketone organic solvent is selected from butanone.

An embodiment of the present invention also provides a method for preparing a modified polyurethane resin, including the following steps S10 to S40.

S10, providing the following raw materials in percentage by weight: 4.2 to 7.6 percent of polyisocyanate compound, 8 to 10 percent of polycarbonate diol compound, 0.2 to 1.0 percent of diol compound containing acid groups, 0.5 to 10 percent of polyethylene glycol acrylate compound, 7.45 to 30.84 percent of acrylate monomer, 0.01 to 0.05 percent of catalyst, 0.05 to 0.5 percent of initiator, 1.2 to 1.7 percent of neutralizer, 10 to 18 percent of organic solvent and 44.0 to 54.0 percent of water.

In some embodiments, in step S10, the method further comprises the step of removing water from the carbonate diol compound, wherein the water content of the carbonate diol compound is controlled to be less than 0.05%.

In some embodiments, the water removal step is performed under negative pressure; further, the reaction is carried out under the conditions that the pressure is not less than-0.09 MPa and the temperature is 95-105 ℃.

And S20, mixing the polyisocyanate compound, the polycarbonate diol compound and part of the organic solvent, and carrying out prepolymerization reaction to obtain a prepolymer.

In some of these embodiments, the pre-reaction conditions are: reacting for 15-30 min at 70-90 ℃.

In the pre-reaction process, a polyisocyanate compound and a polycarbonate diol compound react to form a prepolymer with low polymerization degree.

In some embodiments, the mass of the part of the organic solvent added in step S20 accounts for 5% -17% of the total mass of the organic solvent; further, part of the organic solvent added in step S20 is a ketone organic solvent, and further, the organic solvent is butanone.

And S30, mixing the prepolymer prepared in the step S20 with a catalyst, adding a diol compound containing an acidic group and a part of acrylate monomers after the first-stage reaction, and obtaining a polyurethane prepolymer after the second-stage reaction.

Under the action of catalyst, the low molecular prepolymer is polymerized gradually to form high polymerization degree molecule through the first stage reaction.

In some of these embodiments, the conditions of the first stage reaction are: reacting for 1-4 h at 70-90 ℃. Further, after the first-stage reaction, the NCO value of the reaction system is 6.48-12.80%.

Under the action of a catalyst, reacting a diol compound containing an acidic group and a part of acrylate monomers with NCO groups on a polyisocyanate compound through a first-stage reaction, so that polyurethane molecules are subjected to chain extension to obtain a high-molecular-weight polyurethane prepolymer.

Unsaturated double bonds are introduced on polyurethane molecules by introducing acrylate monomers, so that the polyurethane molecules are modified in the next step. Meanwhile, the acid groups in the diol compound containing the acid groups are hydrophilic groups, so that the dispersibility of the polyurethane in water can be further improved.

In some of these embodiments, the conditions for the second stage reaction are: reacting for 2-4 h at 70-100 ℃. The NCO value of the polyurethane obtained after the second stage reaction is 1.5-4.0%.

And S30, simultaneously dripping the polyethylene glycol acrylate compound, the rest of acrylate monomer and the initiator into the mixture of the polyurethane prepolymer and the rest of organic solvent, adding a neutralizer after the third-stage reaction, adding the water after the neutralization reaction, and emulsifying to obtain the modified polyurethane resin.

The polyethylene glycol acrylate compound and the acrylate monomer are subjected to free radical polymerization with double bonds in polyurethane under the action of an initiator, so that the polyethylene glycol acrylate compound and the acrylate monomer are introduced into polyurethane molecules.

On one hand, the introduction of the polyethylene glycol acrylate compound and the acrylate monomer enables the polyurethane resin to have a hydrophilic chain segment structure which has excellent hydration stability and water compatibility; on the other hand, the polyethylene glycol acrylate structure can form an intramolecular hydrogen bond and can also form a hydrogen bond with a hydrophilic solvent, so that the stability of the modified polyurethane in water is further improved.

Furthermore, acidic groups in the modified polyurethane are neutralized into salts by a neutralizing agent, so that the resin with the nonionic hydrophilic chain segment is obtained, and the dispersibility of the resin in water is improved, and the storage stability of the resin is improved.

In some embodiments, the conditions of the third stage reaction are: reacting for 1-3 h at 70-100 ℃.

In some of these embodiments, the conditions of the neutralization reaction are: reacting for 0.5-1 h at 50-90 ℃.

In some of the embodiments, the remaining portion of the organic solvent added in step S30 is an alcoholic organic solvent.

In some embodiments, the mass of the remaining portion of the acrylate monomers added in step S30 is 5% to 17% of the total mass of the acrylate monomers.

An embodiment of the invention also provides an application of any one of the modified polyurethane resins or the modified polyurethane resin prepared by any one of the preparation methods in preparing a coating.

Further, an embodiment of the present invention provides an aqueous coating material containing any of the modified polyurethane resins described above or the modified polyurethane resin obtained by any of the above-described production methods.

The water-based paint comprises the modified polyurethane resin, the modified polyurethane resin can improve the storage stability of the paint, and the modified polyurethane resin can be uniformly dispersed in a water-based solvent, so that the paint can be prevented from generating aggregates, and a formed coating film product is smooth and has good flatness.

In some of these embodiments, the aqueous coating further comprises an adjuvant.

It is understood that the above-mentioned auxiliaries can be selected according to the actual application of the coating, and for example, the auxiliaries belonging to the aspect of improving the surface activity of the coating are dispersants, wetting agents, emulsifiers, demulsifiers, antifoaming agents, foaming agent antistatic agents, etc.; the auxiliary agents with catalytic action include initiator, drier, curing agent, coupling agent, polymerization inhibitor, photoinitiator, anti-skinning agent, antioxidant, anti-microbial agent, mildew preventive and the like; belongs to functional additives such as metal powder, graphite powder, carbon fiber and the like which are required to be added into conductive paint, and materials which can absorb and dissipate gamma rays such as titanium, aluminum, chromium and the like adopted by radiation-proof paint.

An embodiment of the present invention further provides a coated article including a coating film formed from the above aqueous coating material.

The water-based paint has high storage stability, is uniformly dispersed in water, can avoid the generation of aggregates in the storage and construction processes of the paint, and can avoid the formation of a mixed layer particularly when the water-based 3wet 3C1B coating process is carried out, so that the formed coating film is smooth and has good flatness.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The modified polyurethane resin and the process for producing the same, the aqueous coating material and the coated article according to the present invention are exemplified herein, but the present invention is not limited to the following examples.

Example 1

1) In a reaction kettle, a polycarbonate hexanediol (Mw is 3000) compound is dehydrated at 105 ℃ for 2 hours under the negative pressure condition of-0.09 MPa until the water content of the polycarbonate hexanediol is 0.02%.

2) Adding 8g of polycarbonate hexanediol, 4.2g of isophorone diisocyanate and 3g of butanone into a reaction kettle, and carrying out pre-reaction for 30min at 70 ℃ to obtain a prepolymer; then 0.01g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃, and the measured NCO value of the system is 7.7%; then, 0.2g of dimethylolpropionic acid and 2.5g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer, and the NCO value of the polyurethane prepolymer system was measured to be 1.6%.

3) Adding 13g of tripropylene glycol monomethyl ether into a reaction kettle, and then dropping 0.5g of methoxypolyethylene glycol methacrylate (Mn 1000), 16.56g of butyl acrylate, 0.9g of acrylic acid, 2.31g of styrene and 0.5g of azobisisobutyronitrile into the reaction kettle simultaneously at 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.24g of N, N-dimethylethanolamine, and carrying out neutralization reaction for 0.5 hour; finally, 47.08g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Example 2

1) In a reaction kettle, a polycarbonate hexanediol (Mw 1000) compound is dehydrated at 105 ℃ for 2 hours under the negative pressure condition of-0.09 MPa until the water content of the polycarbonate hexanediol is 0.02%.

2) Adding 8.6g of polycarbonate hexanediol, 5.4g of xylylene diisocyanate and 1g of butanone into a reaction kettle, and carrying out pre-reaction for 30min at 70 ℃ to obtain a prepolymer; then 0.02g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃, and the measured NCO value of the system is 9.3%; then, 0.5g of dimethylolbutyric acid and 3g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer, and the NCO value of the polyurethane prepolymer system was measured to be 1.6%.

3) Adding 11.5g of tripropylene glycol monomethyl ether into a reaction kettle, and then dropping 6g of methoxypolyethylene glycol methacrylate (Mn 1000), 10g of butyl acrylate, 0.7g of acrylic acid, 0.93g of styrene and 0.05g of azobisisobutyronitrile into the reaction kettle simultaneously at 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.3g of triethylamine, and carrying out neutralization reaction for 0.5 hour; finally, 51g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Example 3

1) In a reaction kettle, a polycarbonate hexanediol (Mw ═ 2000) compound is dehydrated at 105 ℃ for 2 hours under the negative pressure condition of-0.09 MPa until the water content of the polycarbonate hexanediol is 0.02%.

2) 9.3g of polycarbonate hexanediol, 6.5g of hydrogenated diphenylmethane diisocyanate and 1.5g of butanone are added into a reaction kettle, and pre-reaction is carried out for 30min at the temperature of 70 ℃ to obtain a prepolymer; then 0.05g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃, wherein the NCO value of the system is 10.3%; then, 0.8g of dimethylolpropionic acid and 3.5g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer, and the NCO value of the polyurethane prepolymer system was measured to be 1.6%.

3) Adding 15g of tripropylene glycol monomethyl ether into a reaction kettle, and then dripping 10g of methoxypolyethylene glycol methacrylate (Mn ═ 2000), 2.3g of butyl acrylate, 0.5g of acrylic acid, 1.6g of styrene and 0.2g of azobisisobutyronitrile into the reaction kettle simultaneously at the temperature of 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.5g of methyl monoethanolamine, and carrying out neutralization reaction for 0.5 hour; finally, 47.25g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Example 4

2) Adding 10g of polycarbonate hexanediol, 7.6g of isophorone diisocyanate and 2g of butanone into a reaction kettle, and carrying out pre-reaction for 30min at 70 ℃ to obtain a prepolymer; then 0.04g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃, wherein the NCO value of the system is 11.1%; then, 0.2g of dimethylolpropionic acid and 4g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer, and the NCO value of the polyurethane prepolymer system was measured to be 1.6%.

3) Adding 10g of tripropylene glycol monomethyl ether into a reaction kettle, and then dropping 3g of methoxypolyethylene glycol methacrylate (Mn ═ 2000), 4.51g of butyl acrylate, 0.4g of acrylic acid, 4.7g of styrene and 0.35g of azobisisobutyronitrile into the reaction kettle simultaneously at 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.64g of N, N-dimethylethanolamine, and carrying out neutralization reaction for 0.5 hour; finally, 50.76g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Comparative example 1

2) Adding 8.6g of polycarbonate hexanediol, 5.4g of xylylene diisocyanate and 1g of butanone into a reaction kettle, and carrying out pre-reaction at 70 ℃ for 30min to obtain a prepolymer; then 0.02g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃; then, 0.5g of dimethylolbutyric acid and 3g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer.

3) Adding 11.5g of tripropylene glycol monomethyl ether into a reaction kettle, and then dripping 16g of butyl acrylate, 0.7g of acrylic acid, 0.93g of styrene and 0.05g of azobisisobutyronitrile into the reaction kettle simultaneously at the temperature of 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.3g of triethylamine, and carrying out neutralization reaction for 0.5 hour; finally, 57g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Comparative example 2

2) Adding 8.6g of polycarbonate hexanediol, 5.4g of xylylene diisocyanate and 1g of butanone into a reaction kettle, and carrying out pre-reaction at 70 ℃ for 30min to obtain a prepolymer; then 0.02g of catalyst dibutyltin dilaurate is added, and the reaction is carried out for 2 hours at 70 ℃, and the measured NCO value of the system is 9.3%; then, 0.5g of dimethylolbutyric acid and 3g of hydroxyethyl methacrylate were added thereto and reacted at 80 ℃ for 4 hours to obtain a polyurethane prepolymer, and the NCO value of the polyurethane prepolymer system was measured to be 1.6%.

3) Adding 11.5g of tripropylene glycol monomethyl ether into a reaction kettle, and then dropping 14g of methoxypolyethylene glycol methacrylate (Mn 1000), 2g of butyl acrylate, 0.7g of acrylic acid, 0.93g of styrene and 0.05g of azobisisobutyronitrile into the reaction kettle simultaneously at 100 ℃ for reaction for 3 hours; then cooling to 50 ℃, adding 1.3g of triethylamine, and carrying out neutralization reaction for 0.5 hour; finally, 51g of deionized water is added, and emulsification is carried out under the high-speed dispersion condition with the linear speed of 8 m/s; cooling and filtering to obtain the modified polyurethane resin.

Comparative example 3

Comparative example 3 is substantially the same as example 2 except that: in comparative example 3, the polyethylene glycol acrylate compound used in example 1 was replaced with methoxypolyethylene glycol maleamide (polyethylene glycol segment molecular weight 1000). The method comprises the following specific steps:

the composition formulas of examples 1 to 4 and comparative examples 1 to 3 are shown in Table 1.

TABLE 1

The measurement results show that the performance parameters of the modified polyurethane resins prepared in examples 1 to 4 and comparative examples 1 to 3 are shown in Table 2.

TABLE 2

Example 5: preparation of aqueous middle coating

The water-based intercoat coating is prepared by charging according to the formula table of the water-based coating in table 2, and comprises the following steps:

(1) under the stirring condition that the online speed is 5m/s, sequentially adding the weighed Bayhydrol U241 polyester polyurethane dispersoid, BYK-190 dispersing agent, BYK-011 defoaming agent, MA-100 carbon black, R-706 titanium dioxide, Shahareli precipitated barium sulfate, gas phase silicon dioxide anti-settling agent and a part of deionized water into a grinding kettle, uniformly mixing, stirring for 0.5h, and then grinding to the fineness of below 10 mu m to obtain a component a;

(2) under the stirring condition with the linear speed of 3m/s, sequentially adding the weighed Cy327 high imino group amino resin, Cy370 partially methylated amino resin, SURFYNOL 104A defoaming and leveling agent and BYK-346 substrate wetting agent into a blending kettle, and stirring for 0.5h and uniformly mixing to obtain a component b;

(3) under the stirring condition with the linear speed of 3m/s, uniformly mixing the component a and the modified polyurethane resin prepared in the embodiment 1, then adding the component b, uniformly mixing, then adding the Additol XW395 anti-shrinkage additive, stirring for 0.5h, and uniformly mixing to obtain a mixed material;

(4) adding a pH value regulator (methylethanolamine) and the rest of deionized water into the obtained mixture under the stirring condition of the linear speed of 3m/s, stirring for 0.5h, uniformly mixing, and filtering by using 200-mesh silk cloth to prepare the water-based floating coating.

Example 6

The waterborne floating coat is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the embodiment 2 are firstly mixed uniformly under the stirring state with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

Example 7

The water-based floating coat paint is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the embodiment 3 are firstly mixed uniformly under the stirring condition with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

Example 8

The water-based floating coat paint is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the embodiment 4 are firstly mixed uniformly under the stirring condition with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

Comparative example 4

A water-based floating coat paint was prepared according to the method of example 5, except that in the step (3), the component a and the component b were directly and uniformly mixed under the stirring condition of the linear speed of 3m/s, then Additol XW395 anti-cratering assistant was added, and the mixture was uniformly mixed by stirring for 0.5h to obtain a mixed material.

Comparative example 5

The waterborne floating coat is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the comparative example 1 are firstly mixed uniformly under the stirring condition with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

Comparative example 6

The waterborne floating coat is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the comparative example 2 are firstly mixed uniformly under the stirring condition with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

Comparative example 7

The waterborne floating coat is prepared according to the method of the embodiment 5, except that in the step (3), the component a and the modified polyurethane resin prepared in the comparative example 3 are firstly mixed uniformly under the stirring condition with the linear speed of 3m/s, then the component b is added and mixed uniformly, then the Additol XW395 anti-shrinkage additive is added, and the mixture is stirred for 0.5h and mixed uniformly to obtain the mixed material.

The formulation of the aqueous basecoat is shown in table 3.

TABLE 3

Performance testing

1) The aqueous coating materials prepared in comparative examples 4 to 7 and examples 5 to 8 were sealed in a white plastic bottle having a diameter of 8.5cm and a height of 17cm, and stored in a thermostat at 50 ℃ for 30 days, and then the coating state was observed. The results are shown in Table 4 below.

TABLE 4

	State of coating before storage	After 30d (50 ℃ C.)
			Example 5	Uniformity	Layered 2mm
Example 6	Uniformity	All have no layering
			Example 7	Uniformity	All have no layering
Example 8	Uniformity	Layered 1mm
			Comparative example 4	Uniformity	5mm in layers
Comparative example 5	Uniformity	Layered 4mm
			Comparative example 6	Uniformity	Layered 3mm
Comparative example 7	Uniformity	Layered 3mm

As can be seen from the above table, the polyethylene glycol acrylate compound is advantageous in improving the storage stability of the resin.

Example 9

The coating is prepared by the following specific steps:

phosphate plates (PB-L3020, traded Rice-flour noodles, Japan) and electrophoretic cathode electrophoretic primer (20 to 25 μm thick, HT8000 electrophoretic primer, Hunan Jiangxi coating Co., Ltd.), were baked at 175 ℃ for 20min and left at room temperature for 24 hours or more.

The base paint is WBC-721H silver color and WBC-721H white color sold by Hunan Xiangjiang Guanxi paint Co., Ltd, and the varnish is KINO400H sold by Hunan Xiangjiang Guanxi paint Co., Ltd.

The finish paint spraying process comprises the following steps: any one of the water-based coatings prepared in the examples 5-8 or the comparative examples 4-7 is adopted for spraying, the thickness of a dry film is controlled to be 20-25 mu m, and the leveling time is 6 min; spraying WBC-721 silver finish paint to control the thickness of the dry film to be 10-14 mu m or spraying WBC-721 white finish paint to control the thickness of the dry film to be 25-30 mu m, and leveling for 8 min; pre-baking in an oven at 80 ℃ for 5min, cooling, spraying KINO400H varnish, leveling for 10min, baking in an oven at 150 ℃ for 20min (timing after ensuring that the temperature of the test panel reaches 150 ℃) to form a film integrally.

The method for testing the film thickness of each coating of the finish paint comprises the following steps: spraying any coating with a blank tinplate, leveling for 10min, baking at 150 deg.C for 20min, and testing with film thickness tester.

Among them, when any of the water-based paints obtained in examples 5 to 8 was used for spray coating, the obtained coating films were designated as coating films 5, 6, 7, and 8, and when any of the water-based paints obtained in comparative examples 4 to 7 was used for spray coating, the obtained coating films were designated as comparative coating films 4, 5, 6, and 7.

And (3) testing the DOI value (image definition) and the L/S value (long and short wave value) of the prepared corresponding coating, wherein the testing and evaluating method comprises the following steps:

DOI value: the data can be displayed directly based on direct testing by a "WaveScan" orange peel instrument (manufactured by BYKGardner, germany). A higher DOI value indicates a better visual appearance of the composite coating film, whereas a poor visual appearance of the coating film.

L/S value: the data can be displayed directly based on direct testing by a "WaveScan" orange peel instrument (manufactured by BYKGardner, germany). The automobile coating industry generally requires that the L value is less than 20, the S value is less than 10, the smaller the L/S value is, the higher the flatness of the coating film is, and the worse the flatness is.

Specific wear layer parameters and test results are shown in tables 5 and 6. In table 5, silver coating films and white coating films are shown in table 6.

TABLE 5

TABLE 6

As can be seen from the results in tables 5 and 6, the appearance data of the coating film obtained by spraying the water-based paint of the comparative example 4 can not meet the requirements, and from the data tested by a silver-color matched test plate, the upper layer finish paint has the back penetration to the lower layer middle paint, so that the aluminum powder is disorderly arranged, and the appearance data is deteriorated; compared with the matching white paint, the white paint has no problem of arrangement of the flaky effect pigment, so the appearance data is better than that of silver. The coating films obtained by spraying the waterborne floating coat paint of the examples 5-8 have the advantage of anti-mixing layer due to the modified polyurethane resin prepared in the examples 1-4, and the problem of back permeation of the sprayed waterborne floating coat paint which is sprayed subsequently and matched with the waterborne base paint can be solved. Therefore, the appearance data of the coating films obtained by spraying the water-based paint of examples 5-8 can meet the appearance requirements in the automobile paint industry.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only show some embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The modified polyurethane resin is characterized in that the modified polyurethane resin is prepared from the following raw materials in percentage by weight: 4-8% of polyisocyanate compound, 8-10% of polycarbonate diol compound, 0.2-1.0% of diol compound containing acidic groups, 0.5-10% of polyethylene glycol acrylate compound, 7-31% of acrylate monomer, 0.01-0.05% of catalyst, 0.05-0.5% of initiator, 1-2% of neutralizer, 10-18% of organic solvent and 44.0-54.0% of water.

2. The modified polyurethane resin as claimed in claim 1, wherein the modified polyurethane resin is prepared from the following raw materials in percentage by weight: 5-8% of polyisocyanate compound, 8-10% of polycarbonate diol compound, 0.2-1.0% of diol compound containing acidic groups, 4-10% of polyethylene glycol acrylate compound, 7-25% of acrylate monomer, 0.01-0.05% of catalyst, 0.05-0.5% of initiator, 1.2-1.7% of neutralizer, 10-18% of organic solvent and 44.0-54.0% of water.

3. The modified polyurethane resin of claim 1, wherein the polyethylene glycol acrylate compound has a structure represented by formula (i):

wherein R is₁Any one selected from alkyl with 1-4 carbon atoms; r₂Is selected from methyl or hydrogen atoms, and n is an integer of 1-500.

4. The modified polyurethane resin according to claim 1, wherein the modified polyurethane resin has a solid content of 35 to 45 wt%, a viscosity of 10 to 500 mpa-s, a pH of 6.0 to 8.0, a weight-average molecular weight of 60000 to 150000, and an acid value of 10 to 40 mgKOH/g.

5. The modified polyurethane resin according to any one of claims 1 to 4, wherein the polycarbonate diol compound is selected from polycarbonate diols having a weight average molecular weight of 500 to 4000; the polyisocyanate compound is at least one selected from the group consisting of alicyclic diisocyanate and aromatic diisocyanate.

6. The modified polyurethane resin according to any one of claims 1 to 4, wherein the acid group in the acid group-containing diol compound is a carboxyl group.

7. The modified polyurethane resin according to any one of claims 1 to 4, wherein the catalyst is an organometallic catalyst; the initiator is selected from a peroxy compound initiator or an azo compound initiator; the neutralizing agent is selected from small molecule amine compounds.

8. The modified polyurethane resin according to any one of claims 1 to 4, wherein the acrylate monomer is at least one selected from the group consisting of isobornyl methacrylate, isobornyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, styrene, butyl acrylate, butyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, isooctyl acrylate, isooctyl methacrylate, phosphate acrylate, phosphate methacrylate, acrylic acid and methacrylic acid.

9. A preparation method of modified polyurethane resin is characterized by comprising the following steps:

and simultaneously dripping the polyethylene glycol acrylate compound, the rest of the acrylate monomer and the initiator into the mixture of the polyurethane prepolymer and the rest of the organic solvent, adding a neutralizer after the third-stage reaction, adding the water after the neutralization reaction, and emulsifying to obtain the modified polyurethane resin.

10. The process for producing a modified polyurethane resin according to claim 9, wherein the conditions for the first-stage reaction are: reacting for 1-4 h at 70-90 ℃; and/or

11. Use of the modified polyurethane resin according to any one of claims 1 to 8 or the aqueous polyurethane resin obtained by the production method according to any one of claims 9 to 10 for producing a coating material.

12. An aqueous coating material, characterized in that the coating material contains the modified polyurethane resin described in any one of 1 to 8 or the modified polyurethane resin obtained by the production method described in any one of claims 9 to 10.

13. A coated article comprising a coating film formed from the aqueous coating composition according to claim 12.