CN120574496B

CN120574496B - A kind of odorless coating film-forming aid and preparation method thereof

Info

Publication number: CN120574496B
Application number: CN202511080464.2A
Authority: CN
Inventors: 刘木林
Original assignee: Sipson New Materials Shanghai Co ltd
Current assignee: Sipson New Materials Shanghai Co ltd
Priority date: 2025-08-04
Filing date: 2025-08-04
Publication date: 2025-09-30
Anticipated expiration: 2045-08-04
Also published as: CN120574496A

Abstract

The present invention belongs to the technical field of film-forming agents, and in particular relates to a film-forming agent for odorless coatings and a preparation method thereof. The active polymer in the film-forming agent uses renewable polyphenol ellagic acid as a starting material, utilizes the multiple phenolic hydroxyl groups in its structure to react with propylene oxide through ring-opening polymerization to form a polyether segment, and then introduces disulfide through acylation and nucleophilic substitution reactions to prepare the film-forming agent. The film-forming agent has a boiling point of over 290°C and is an odorless film-forming agent. When used in civilian water-based coatings, it will not cause the coating to produce an unpleasant odor, can effectively increase the film-forming speed of the coating, and can also improve the gloss, impact resistance and wear resistance of the coating.

Description

Odor-free coating film-forming additive and preparation method thereof

Technical Field

The invention relates to the technical field of film forming aids, in particular to a film forming aid for an odor-free coating and a preparation method thereof.

Background

Film forming aids are one of the important components of the coating. The film forming auxiliary agent is beneficial to film forming of the paint, and good film forming property can improve the overall performance of the paint, reduce the porosity and further improve the performance of a paint film, such as scrubbing resistance, water washing property and luster. The selection of the film forming aid is therefore critical to producing good coatings.

Solvent-borne coatings typically employ a relatively high molecular weight resin as the binder, which is a homogeneous system capable of forming a continuous coating film as the solvent evaporates. However, the aqueous coating material using water as a medium is a heterogeneous polymer, and the film is formed by deformation and fusion of the water volatile polymer particles. The softer the polymer, the better the fusion and the denser the film. However, the coating often requires a certain flexibility and hardness, so that the glass transition temperature of the polymer is designed to be higher, the minimum film forming temperature is usually higher than room temperature, and if the coating needs to wait for curing under the condition of room temperature, the film forming speed is too slow, and the blocking resistance and the wear resistance of the coating film are poor.

The Chinese patent application with publication number of CN107974115A discloses a coating film forming agent, which adopts styrene resin, isooctyl acrylate, C9 petroleum resin and urea resin as base materials, and methyl cellulose, triethyl borate, ethylene glycol dimethacrylate and seaweed gel are added, so that the prepared film forming agent has good spreadability, flatness and adhesiveness, and the protection effect and the service life of the coating are effectively improved. Resin-based film formers are commonly used in solvent-borne coatings, where defects in the coating of the aqueous coating are typically caused by imbalances in the rate of water evaporation and resin condensation, differences in surface tension, and the like.

The main component of the film-forming auxiliary agent commonly used for the water-based paint is dodecanol ester, and the preparation raw material is isobutyraldehyde. The dodecanol ester has an pungent smell, the volatile gas can stimulate the respiratory tract, the paint can generate unpleasant smell when being used in civil paint, the health of construction personnel and users is influenced, the boiling point of the dodecanol ester is 250-255 ℃, the dodecanol ester belongs to low-VOC paint, and finally the dodecanol ester volatilizes to the atmosphere to cause ecological pollution.

Disclosure of Invention

The invention aims to provide an odor-free coating film-forming additive and a preparation method thereof. According to the technical scheme, the polyether chain segment is prepared by ring-opening polymerization of phenolic hydroxyl groups of ellagic acid and propylene oxide, disulfide bonds are introduced into the chain segment, the polymer is prepared, isooctyl adipate is used as a solvent, dioctyl terephthalate with high boiling point and low volatility is added as a plasticizer, oleic acid polyoxypropylene ether is used as a surfactant, the boiling point of the prepared film forming additive exceeds 290 ℃, the film forming additive is an odor-free film forming additive, unpleasant odor of the coating can not be generated when the film forming additive is used in civil water-based paint, the influence on health of constructors and users is avoided, and meanwhile, the glossiness, the friction resistance and the impact resistance of the water-based paint can be improved.

The invention provides an odor-free coating film-forming auxiliary agent which comprises a polymer, a first solvent, a stabilizer, a surfactant and a plasticizer, wherein the mass ratio of the polymer to the first solvent to the stabilizer to the surfactant to the plasticizer is 1 (2-3) (0.012-0.025) (0.011-0.025) (0.2-0.3), the preparation method of the polymer comprises the steps of ring-opening polymerization of ellagic acid and propylene oxide to form a polyether chain segment, and then introducing disulfide bonds to prepare the polymer, and the structural formula of the polymer is as follows:

,

wherein n is an integer between 4 and 8.

Preferably, the first solvent is isooctyl adipate.

Preferably, the stabilizer is any one or more of glycerol, acrylic acid copolymer sodium salt, hydroxyethyl cellulose and ammonium dihydrogen phosphate.

Preferably, the surfactant is oleic acid polyoxypropylene ether.

Preferably, the plasticizer is dioctyl terephthalate.

The invention also provides a preparation method of the odor-free paint film-forming auxiliary agent, which comprises the following steps:

S1, dissolving ellagic acid in a second solvent, adding a catalyst, carrying out a first reaction under the protection of nitrogen and in the dark to obtain an intermediate, continuously adding propylene oxide into the intermediate system, and carrying out a second reaction to obtain an ellagic acid derivative;

S2, dissolving an ellagic acid derivative in a third solvent, adding triethylamine, adding p-toluenesulfonyl chloride under the ice bath condition, and reacting to obtain a sulfonylated ellagic acid derivative;

S3, dropwise adding the 2-hydroxyethyl disulfide into a sodium hydroxide alcohol solution, and reacting to obtain a sodium salt of the 2-hydroxyethyl disulfide;

And S4, dissolving the sulfonylated ellagic acid derivative in a second solvent, adding sodium salt of 2-hydroxyethyl disulfide under stirring, reacting, adding dilute hydrochloric acid to terminate the reaction, centrifuging, collecting solids, and washing to obtain the polymer.

And S5, dissolving the polymer in a first solvent, adding a stabilizer, a surfactant and a plasticizer, and stirring to obtain the film forming auxiliary agent.

Preferably, in the step S1, the second solvent is any one or more of N, N-dimethylformamide and dimethyl sulfoxide.

Preferably, in the step S1, the catalyst is any one or more of sodium carbonate, potassium carbonate and triethylamine.

Preferably, in the step S1, the temperature of the first reaction is 40 to 55 ℃, and the time of the first reaction is 1 to 3 hours.

Preferably, in the step S1, the temperature of the second reaction is 60 to 100 ℃, and the time of the second reaction is 5 to 10 hours.

Preferably, in the step S1, the mass ratio of ellagic acid, the second solvent, the catalyst and propylene oxide is 1 (2-3): 0.05-0.15): 0.15-0.45.

Preferably, in the step S2, the third solvent is any one or more of dichloromethane and tetrahydrofuran.

Preferably, in the step S2, the reaction temperature is 25-50 ℃ and the reaction time is 6-12 hours.

Preferably, in the step S2, the mass ratio of the ellagic acid derivative, the third solvent, the triethylamine and the p-toluenesulfonyl chloride is 1 (2-3): 1.5-3): 1.1-1.5.

Preferably, in the step S3, the mass ratio of the sodium hydroxide to the absolute ethyl alcohol in the sodium hydroxide alcohol solution is 1 (5-9).

Preferably, in the step S3, the reaction temperature is 50-80 ℃ and the reaction time is 0.5-2 hours.

Preferably, in the step S3, the mass ratio of the 2-hydroxyethyl disulfide to the sodium hydroxide alcohol solution is 1 (1.5-2).

Preferably, in the step S4, the temperature of the stirring is 20 to 30 ℃.

Preferably, in the step S4, the reaction temperature is 50-80 ℃ and the reaction time is 6-12 hours.

Preferably, in the step S4, the washed solvent is diethyl ether.

Preferably, in the step S4, the mass ratio of the sulfonylated ellagic acid derivative, the second solvent, and the sodium salt of 2-hydroxyethyl disulfide is 1 (2-3): 1.1-1.5.

Preferably, in the step S5, the stirring temperature is 30-45 ℃, and the stirring time is 0.5-1h.

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

(1) The application adopts ellagic acid as a core, utilizes hydroxyl in the ellagic acid structure and epoxypropane to introduce a polyether chain segment on the ellagic acid through ring-opening polymerization, and introduces a chain segment containing disulfide bonds through acylation and nucleophilic substitution reaction to prepare a novel polymer. Ellagic acid molecules contain a plurality of phenolic hydroxyl groups, and multiple reaction sites are provided, so that the prepared polymer has higher branching degree. Under the condition that the molecular weight of the branched chains is the same, the inter-molecular chain entanglement degree of the polymer with high branching degree is obviously lower than that of the polymer with low branching degree, the movement of the main chain is hindered by the branched chains to a certain extent, the tight contact and entanglement opportunities among the main chains are reduced, and relative sliding and diffusion are easier to occur in a solution or in the film forming process, so that the film forming speed of the coating can be obviously accelerated, secondly, the branched chain segments of the polymer with high branching degree can obstruct the close arrangement of the chain segments, reduce the formation of inter-chain hydrogen bonds and Van der Waals force, reduce the glass transition temperature, and therefore, the curing temperature of the coating can be obviously reduced.

(2) In the polymer prepared in the application, the chain segment containing disulfide bonds is introduced on the polyether chain segment through acylation and nucleophilic substitution reaction, and the impact resistance and the wear resistance of the coating containing the polymer film forming additive are obviously improved. The friction stress causes the disulfide bond to be broken preferentially in the abrasion-resistant aspect, the energy transferred to a matrix is reduced, the sulfur radicals generated after breaking are recombined rapidly, the crosslinked structure of a molecular chain is recovered, and the abrasion of the material caused by permanent breaking is avoided.

(3) The boiling point of the film forming auxiliary agent prepared by the application exceeds 290 ℃, and the intermolecular dipolar acting force is enhanced due to the disulfide bonds introduced in the molecular chains of the high molecular weight polymer, so that the vaporization is realized by overcoming the intermolecular acting force with higher energy, and the boiling point is increased. The isooctyl adipate is used as a solvent and is compounded with dioctyl terephthalate, so that the boiling point of a system can be improved, and oleic acid polyoxypropylene ether with high boiling point is added as a surfactant, so that particles in the system are prevented from agglomerating through steric hindrance and electrostatic repulsion to form stable dispersoid, the contact point between molecules is increased in the dispersion state, the whole system can be boiled by destroying the action force between molecules with higher energy, and the boiling point of the system is further improved.

(4) In the technical scheme of the application, renewable phenols are adopted to replace common petroleum-based phenols, so that the carbon footprint is reduced. The film-forming additive prepared from the obtained polymer can reduce VOC content, because the polymer with high branching degree has low intrinsic viscosity, even under high solid content, the melt viscosity is still obviously lower than that of the linear polymer, the existence of the branched chains can enable the molecular chains to be piled up more densely, so that the free volume among molecules is reduced, the linear molecules are not branched, the molecular chains piled up are not branched, so that the free volume is relatively more, but the inter-molecular chain entanglement of the linear molecules is serious, the free volume distribution is uneven, so that the movement of the molecular chains is blocked, the branched molecular chains have low free volume, but the entanglement degree among the molecular chains is low, the molecular chains are arranged more uniformly, so that the free volume distribution is uniform and more regular, the molecular chains can slide more efficiently in a limited space, the polymer can keep the fluidity required by construction under low solvent content, and chemical bonds such as disulfide bonds in the polymer molecules can be rapidly crosslinked and fixed in solvent, so that VOC generation and release are inhibited. Whereas low-branching polymers, especially linear structure polymers, have a high entanglement of molecular chains, they rely on organic solvents such as toluene, xylene, etc. to reduce viscosity.

Drawings

FIG. 1 is a flow chart of the preparation of a odor control coating film forming aid.

FIG. 2 is a schematic diagram of a polymer synthesis route.

Detailed Description

The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.

The sodium salt type of the acrylic copolymer used in examples and comparative examples was disperbx 8070n (Sidersen New Material (Shanghai) Co., ltd.).

Reagents and equipment according to the examples described below were purchased commercially unless otherwise specified.

Example 1

As shown in fig. 1, a film forming aid for an odor-free coating is prepared by a process comprising:

step S1, dissolving 10g ellagic acid in 20N, N-dimethylformamide of g, adding 0.5g sodium carbonate, reacting at 40 ℃ under the protection of nitrogen and in the dark for 3 h to obtain an intermediate, continuously adding 1.5 g propylene oxide into the intermediate system, and reacting at 60 ℃ for 10 h to obtain the ellagic acid derivative.

Step S2, dissolving the 10g ellagic acid derivative in 20 g dichloromethane, adding 15 g triethylamine, adding 11 g p-toluenesulfonyl chloride under ice bath condition, and reacting at 25 ℃ for 12 h to obtain the sulfonylated ellagic acid derivative.

Step S3, dissolving 10 g sodium hydroxide in 40 g absolute ethyl alcohol to prepare sodium hydroxide alcohol solution with the concentration of about 20%, adding 10 g 2-hydroxyethyl disulfide into 15g sodium hydroxide alcohol solution with the concentration of 20%, and reacting 2h at 50 ℃ to obtain sodium salt of 2-hydroxyethyl disulfide.

Step S4, dissolving 10g sulfonyl ellagic acid derivative in 20N, N-dimethylformamide of g, adding sodium salt of 2-hydroxyethyl disulfide of 11 g under stirring at 20 ℃, reacting at 50 ℃ for 12 h, adding dilute hydrochloric acid to terminate the reaction, centrifuging to collect solid, and washing the solid with diethyl ether to obtain a polymer, as shown in figure 2.

Step S5, dissolving 10 g polymer in 20 g isooctyl adipate, adding 0.12 g acrylic acid copolymer sodium salt, 0.11 g oleic acid polyoxypropylene ether, 2 g dioctyl terephthalate and stirring at 30 ℃ for 1h to obtain a film forming auxiliary agent.

Example 2

Step S1, dissolving 10 g ellagic acid in 25 g dimethyl sulfoxide, adding 1g potassium carbonate, reacting 2h at 45 ℃ under the protection of nitrogen and in the dark to obtain an intermediate, continuously adding 2.5 g propylene oxide into the intermediate system, and reacting 7h at 75 ℃ to obtain the ellagic acid derivative.

Step S2, dissolving the 10 g ellagic acid derivative in 25 g tetrahydrofuran, adding 20 g triethylamine, adding 12 g p-toluenesulfonyl chloride under ice bath condition, and reacting at 35 ℃ for 9h to obtain the sulfonylated ellagic acid derivative.

Step S3, dissolving 10g sodium hydroxide in 60g absolute ethyl alcohol to prepare sodium hydroxide alcohol solution with the concentration of about 15%, adding 10g 2-hydroxyethyl disulfide into the sodium hydroxide alcohol solution with the concentration of 20 g and 15%, and reacting at 65 ℃ for 1.5 h to obtain sodium salt of 2-hydroxyethyl disulfide.

Step S4, dissolving 10 g sulfonyl ellagic acid derivative in dimethyl sulfoxide of 25 g, adding sodium salt of 2-hydroxyethyl disulfide of 12 g under 25 ℃ stirring, reacting at 65 ℃ for 10 h, adding dilute hydrochloric acid to terminate the reaction, centrifuging, collecting solid, and washing the solid with diethyl ether to obtain the polymer, as shown in figure 2.

Step S5, dissolving 10 g polymer in 25 g isooctyl adipate, adding 0.16 g glycerol, 0.18g oleic acid polyoxypropylene ether, 2.5 g dioctyl terephthalate, and stirring at 35 ℃ for 1h to obtain a film forming additive.

Example 3

Step S1, 10g ellagic acid is dissolved in 20 g dimethyl sulfoxide, 1.5 g triethylamine is added, 1h is reacted under the condition of nitrogen protection and light shielding at 50 ℃ to obtain an intermediate, 3.5 g propylene oxide is continuously added into the intermediate system, and 6h is reacted at 90 ℃ to obtain the ellagic acid derivative.

Step S2, dissolving the 10 g ellagic acid derivative in 20 g tetrahydrofuran, adding 25 g triethylamine, adding 13 g p-toluenesulfonyl chloride under ice bath condition, and reacting at 40 ℃ for 7 h to obtain the sulfonylated ellagic acid derivative.

Step S3, dissolving 10 g sodium hydroxide in 80 g absolute ethyl alcohol to prepare sodium hydroxide alcohol solution with the concentration of about 12%, adding 10 g 2-hydroxyethyl disulfide into 15g sodium hydroxide alcohol solution with the concentration of 12%, and reacting 1 h at 70 ℃ to obtain sodium salt of 2-hydroxyethyl disulfide.

Step S4, dissolving 10g sulfonyl ellagic acid derivative in dimethyl sulfoxide of 20 g, adding sodium salt of 2-hydroxyethyl disulfide of 13 g under 30 ℃ stirring, reacting at 70 ℃ for 8h, adding dilute hydrochloric acid to terminate the reaction, centrifuging, collecting solid, and washing the solid with diethyl ether to obtain the polymer, as shown in figure 2.

Step S5, dissolving 10 g polymer in 25 g isooctyl adipate, adding 0.2 g hydroxyethyl cellulose, 0.22 g oleic acid polyoxypropylene ether and 3g dioctyl terephthalate, and stirring at 40 ℃ for 0.5 h to obtain the film forming additive.

Example 4

Step S1, 10g ellagic acid is dissolved in 30 g dimethyl sulfoxide, 1.5 g triethylamine is added, 1h is reacted under the conditions of nitrogen protection and light shielding at 55 ℃ to obtain an intermediate, 4.5 g propylene oxide is continuously added into the intermediate system, and 5 h is reacted at 100 ℃ to obtain the ellagic acid derivative.

Step S2, dissolving the 10 g ellagic acid derivative in 30 g tetrahydrofuran, adding 30 g triethylamine, adding 15 g p-toluenesulfonyl chloride under ice bath condition, and reacting at 50 ℃ for 6h to obtain the sulfonylated ellagic acid derivative.

Step S3, dissolving 10g sodium hydroxide in 90 g absolute ethyl alcohol to prepare sodium hydroxide alcohol solution with the concentration of about 10%, adding 10g 2-hydroxyethyl disulfide drop by drop into 20 g sodium hydroxide alcohol solution with the concentration of 10%, and reacting at 80 ℃ for 0.5h to obtain sodium salt of 2-hydroxyethyl disulfide.

Step S4, dissolving 10 g sulfonyl ellagic acid derivative in 30 dimethyl sulfoxide of g, adding sodium salt of 2-hydroxyethyl disulfide of 15 g under 30 ℃ stirring, reacting at 80 ℃ for 6h, adding dilute hydrochloric acid to terminate the reaction, centrifuging, collecting solid, and washing the solid with diethyl ether to obtain the polymer.

Step S5, dissolving 10 g polymer in 30 g isooctyl adipate, adding 0.25 g monoammonium phosphate and 0.25 g oleic acid polyoxypropylene ether, 3g dioctyl terephthalate, and stirring at 45 ℃ for 0.5 h to obtain the film forming additive.

Comparative example 1

An odor-free coating film-forming adjuvant was prepared by a process different from example 3 in that phenol was used instead of ellagic acid in step S1.

Comparative example 2

An odor-free coating film forming aid is prepared by a process different from example 3 in that in step S1, p-hydroxyphenol is used instead of ellagic acid.

Comparative example 3

An odor-free coating film forming auxiliary was prepared by a method different from example 3 in that in step S4, the sodium salt of 2-hydroxyethyl disulfide was not added.

Performance test:

The following performance tests were performed on the aqueous acrylic paint, the aqueous polyurethane paint, and the aqueous epoxy resin paint to which the film-forming assistants prepared in examples 1 to 4 and comparative examples 1 to 3 were added, and specifically:

(1) Film forming time of the film forming auxiliaries prepared in examples 1 to 4 and comparative examples 1 to 3 in the aqueous acrylic coating, the aqueous polyurethane coating and the aqueous epoxy resin coating respectively was tested, the prepared film layers were touched with fingers, and the time when fingerprints were no longer displayed on the film layers was recorded, namely the film forming time.

(2) Anti-blocking performance, namely coating paint on a substrate, and drying to form a film. And relatively stacking the surfaces of the two substrates with the coating layers, applying a certain pressure, then placing the substrates in a drying oven, adjusting the temperature to 50-60 ℃, placing the substrates in the drying oven for 24-h, observing the difficulty level of the substrates in separation, and checking the damage level of the surfaces of the coating films. The grade of evaluation was classified into grade A, grade B and grade C, with grade A being the best and grade C being the worst.

(3) Gloss is that coating paint is coated on black matt substrate, and then dried to form film. Gloss of the coating was measured using a gloss meter.

(4) VOC content the VOC contents of the aqueous acrylic, polyurethane and epoxy coatings containing the film-forming aids prepared in examples 1 to 4 and comparative examples 1 to 3 were tested, respectively, according to the method specified in ISO 11890-2-2013.

(5) Impact resistance, namely coating the paint on a substrate, and drying to form a film. The impact tester is placed on a stable platform with the conduit perpendicular to the horizontal plane. The heavy hammer of the impact tester is regulated to a certain height by the heavy hammer controller, a paint film of the test panel faces upwards (positive impact) or faces downwards (recoil) and is horizontally arranged on the base, the distance between the edge of the impact point of the test panel and the edge of the test panel is not less than 10 mm, and the distance between the edges of the adjacent impact points is not less than 10 mm. Pressing the control button of the weight controller, the weight freely drops on the punch. Taking out the test board, observing whether the paint film on the test board has cracks, wrinkles and flaking phenomena under natural sunlight or artificial sunlight, and recording the maximum impact force which can be born by the test board.

(6) Wear resistance the substrate coated with the coating is fixed on a wear tester, the coating is rubbed by a rubber grinding wheel, a weight with a specified weight is added on the rubber grinding wheel, and the abrasion resistance of the coating is measured by the rotation movement of the rubber grinding wheel.

TABLE 1 data for film formation time of coating

According to the data shown in Table 1, the film forming auxiliary agents prepared in examples 1-4 are added into the aqueous acrylic paint, the aqueous polyurethane paint and the aqueous epoxy resin paint, so that the paint can be rapidly formed at normal temperature, wherein the effect of example 3 is best, and the film forming time in the three paints is lower than 15 min. The film forming auxiliary agents prepared in comparative examples 1 to 3 are added into the paint, and the film forming time of the paint is more than 20min, wherein the effect of comparative example 1 is the worst, and the film forming time is more than 30 min.

When the branched molecular weight is the same, the degree of entanglement between the molecular chains of the polymer with a higher degree of branching is significantly lower than that of the polymer with a lower degree of linearity or branching, and therefore, the relative slippage and diffusion of the segments are more likely to occur in the solution or during film formation. In the comparative example 1, phenol is used as a starting material, and compared with the comparative example 1, the comparative example 2 has one more substituent group on the benzene ring of the starting material, but the branching degree of the prepared film forming auxiliary agent is lower than that of the examples 1-3, so that the film forming time of the coating is obviously prolonged.

Table 2 coating blocking resistance test data

Note that the grade was rated as grade a, grade B, and grade C, with grade a being the best and grade C being the worst.

Materials with good blocking resistance generally have better film forming properties because they are capable of forming a continuous and stable film on a substrate, thereby effectively preventing blocking. According to the data shown in Table 2, after the film forming auxiliaries prepared in examples 1 to 4 were added to the three kinds of coatings, the blocking resistance of the coatings was all above A-grade, and the blocking resistance of the coatings prepared in comparative examples 1 to 3 was significantly lower than that of the examples.

The hyperbranched polymer with high branching can form a nanoscale concave-convex structure on the surface of the film, the surface roughening is higher, molecular chains can be distributed more dispersedly, interaction among molecules is weakened, the branched chains block other molecules from approaching to the main chain, excessive entanglement is avoided, therefore, the steric hindrance of each molecular chain is enlarged, the more obvious the steric effect is, the interface contact area is further reduced, the adhesion tendency is reduced, otherwise, the surface roughening is lower, and the smaller the steric hindrance is. The degree of branching of comparative examples 1 and 2 is lower than that of examples 1 to 4, so that the surface roughening degree and steric hindrance of the coating are significantly lower than those of the examples, and the blocking resistance is lower than that of the examples.

Table 3 coating gloss measurement data

As shown in the data of Table 3, the film forming aids prepared in examples 1 to 4 were added to give three coatings having gloss values of 80% or more, and the film forming agents prepared in comparative examples 1 to 3 were added to give three coatings having gloss values of significantly reduced, wherein the film forming aids prepared in comparative example 1 had a gloss value of 58%, the aqueous polyurethane coating material had a gloss value of 64%, and the aqueous epoxy coating material had a gloss value of 55%.

The end of each branched chain of the polymer with high branching degree is usually provided with a functional group, the crosslinking density can reach 3-5 times that of the linear polymer, a uniform three-dimensional network structure is formed, and the volume shrinkage and cracks after film formation are restrained, so that the surface evenness and the gloss retention rate of the film layer are higher than those of a linear system. The low-branching polymer has sparse crosslinking sites, so that the film layer is not shrunk uniformly, microcracks are generated on the surface, and the glossiness is obviously reduced due to the increase of diffuse reflection.

Table 4 paint VOC content measurement data

As shown in the data of Table 4, the VOC content of the coatings added with the film forming aids prepared in examples 1 to 4 is significantly lower than that of the coatings added with the film forming aids prepared in comparative examples 1 to 3.

The polymer with high branching degree has low intrinsic viscosity, even under high solid content, the melt viscosity is obviously lower than that of the linear polymer, the linear polymer has no branched chain and dense molecular chains, but the linear polymer has serious inter-molecular chain entanglement, which can cause uneven free volume distribution and thus prevent molecular chain movement, while the branched molecular chains have low free volume, but have low inter-molecular chain entanglement degree, more uniform molecular chain arrangement and even and more regular free volume distribution, which is favorable for the molecular chains to slide more efficiently in a limited space, thus the polymer can keep the fluidity required by construction under low solvent content, and can quickly crosslink and fix the solvent and inhibit VOC generation and release.

Table 5 impact resistance test data for coatings

As shown in the data of Table 5, the impact resistance of the three coatings added with the film forming aids prepared in examples 1 to 4 is above 50 kg/cm, which is significantly higher than that of the coating added with the film forming aids prepared in comparative examples 1 to 3, wherein the performance of comparative example 3 is the worst, and the impact strength of the three coating coatings is below 40 kg/cm.

In the film-forming auxiliary agent prepared in the comparative example 3, a chain segment containing disulfide bonds is not introduced into the polymer, the bond energy of the disulfide bonds is low, the disulfide bonds can be broken preferentially under the action of external force, the mechanical energy is converted into chemical energy, and after the stress is released, sulfur free radicals can be recombined to form the disulfide bonds, so that the material is restored to the original structure, and permanent damage is avoided. Therefore, disulfide chain segments are introduced into the polymer, so that the impact resistance of the paint coating can be effectively improved.

Table 6 coating wear resistance test data

According to the data shown in Table 6, the coating layers of the three coatings added with the film forming auxiliary agent prepared in examples 1 to 4 are free from any change on the surface of the coating layer after 5000 times of friction, while the coating layer of the three coatings added with the film forming auxiliary agent prepared in comparative example 1 is slightly worn after 5000 times of friction, the coating layer of the aqueous epoxy resin coating added with the film forming auxiliary agent prepared in comparative example 2 is obviously worn after 5000 times of friction, and the coating layer of the three coatings added with the film forming auxiliary agent prepared in comparative example 3 is obviously worn after 5000 times of friction.

The coatings of the three coatings added with the film forming aid prepared in example 1 were slightly worn after 10000 times of friction, the coatings of the aqueous polyurethane coating added with the film forming aid prepared in example 2 were slightly worn after 10000 times of friction, the coatings of the aqueous polyurethane coating and the aqueous epoxy resin coating added with the film forming aid prepared in example 3 were slightly worn after 10000 times of friction, the coatings of the aqueous acrylic coating added with the film forming aid prepared in example 4 were slightly worn after 10000 times of friction, and the coatings of the aqueous polyurethane coating and the aqueous epoxy resin coating added with the film forming aid prepared in comparative example 1 were tilted after 10000 times of friction, the coatings of the aqueous epoxy resin coating added with the film forming aid prepared in comparative example 2 were peeled off after 10000 times of friction, and the coatings of the three coatings added with the film forming aid prepared in comparative example 3 were peeled off after 10000 times of friction.

Experiments prove that the wear resistance of the coating layers added with the film forming auxiliary agents prepared in examples 1-4 is obviously higher than that of the coating layers added with the film forming auxiliary agents prepared in comparative examples 1-3, wherein disulfide bonds are not introduced into the film forming auxiliary agents prepared in comparative example 3, so that the wear resistance is the worst. In the friction process, the stress concentration of the contact interface enables disulfide bonds to be broken preferentially, mechanical energy is converted into chemical energy, energy transferred to a matrix is reduced, sulfur free radicals generated by breaking are recombined rapidly in a stress-free area, a molecular chain crosslinking structure is restored, and material abrasion caused by permanent breaking is avoided.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.

Claims

1. The odor-free paint film-forming auxiliary agent is characterized by comprising a polymer, a first solvent, a stabilizer, a surfactant and a plasticizer, wherein the mass ratio of the polymer to the first solvent to the stabilizer to the surfactant to the plasticizer is 1 (2-3) (0.012-0.025) (0.011-0.025) (0.2-0.3), the preparation method of the polymer comprises the steps of ring-opening polymerization of ellagic acid and propylene oxide to form a polyether chain segment, and then introducing disulfide bonds to prepare the polymer, and the structural formula of the polymer is as follows:

,

wherein n is an integer between 4 and 8.

2. The odor-free coating film-forming auxiliary agent according to claim 1, wherein the first solvent is isooctyl adipate, the stabilizer is any one or more of glycerol, acrylic copolymer sodium salt, hydroxyethyl cellulose and monoammonium phosphate, the surfactant is oleic acid polyoxypropylene ether, and the plasticizer is dioctyl terephthalate.

3. A method of preparing a odor-free coating film forming adjuvant according to claim 1 or 2 comprising:

S4, dissolving the sulfonylated ellagic acid derivative in a second solvent, adding sodium salt of 2-hydroxyethyl disulfide under stirring to react, adding dilute hydrochloric acid to terminate the reaction, centrifuging to collect solids, and washing to obtain a polymer;

4. The method for preparing a film-forming auxiliary agent for an odor-free paint according to claim 3, wherein in the step S1, the second solvent is one or more of N, N-dimethylformamide and dimethyl sulfoxide, and the catalyst is one or more of sodium carbonate, potassium carbonate and triethylamine.

5. The method for preparing the odor-free coating film-forming additive according to claim 3, wherein in the step S1, the temperature of the first reaction is 40-55 ℃, the time of the first reaction is 1-3 hours, the temperature of the second reaction is 60-100 ℃, the time of the second reaction is 5-10 hours, and the mass ratio of ellagic acid, the second solvent, the catalyst and propylene oxide is 1 (2-3): (0.05-0.15): (0.15-0.45).

6. The method for preparing the odor-free coating film-forming auxiliary agent according to claim 3, wherein in the step S2, the third solvent is any one or more of dichloromethane and tetrahydrofuran, the reaction temperature is 25-50 ℃, the reaction time is 6-12 hours, and the mass ratio of ellagic acid derivative, third solvent, triethylamine and p-toluenesulfonyl chloride is 1 (2-3): 1.5-3): 1.1-1.5.

7. The method for preparing the odor-free paint film-forming additive according to claim 3, wherein in the step S3, the mass ratio of sodium hydroxide to absolute ethyl alcohol in the sodium hydroxide alcohol solution is 1 (5-9), the reaction temperature is 50-80 ℃, the reaction time is 0.5-2 h, and the mass ratio of the 2-hydroxyethyl disulfide to the sodium hydroxide alcohol solution is 1 (1.5-2).

8. The method for preparing a film-forming auxiliary agent for an odor-free paint according to claim 3, wherein in the step S4, the stirring temperature is 20-30 ℃, the reaction temperature is 50-80 ℃, and the reaction time is 6-12 hours.

9. The method for preparing a film-forming auxiliary agent for an odor-free paint according to claim 3, wherein in the step S4, the washing solvent is diethyl ether, and the mass ratio of the sulfonylated ellagic acid derivative, the second solvent and the sodium salt of 2-hydroxyethyl disulfide is 1 (2-3): 1.1-1.5.

10. The method for preparing a film-forming auxiliary agent for an odor-free paint according to claim 3, wherein in the step S5, the stirring temperature is 30-45 ℃, and the stirring time is 0.5-1 h.