CN109811093B - Leather protection coating agent and preparation method thereof - Google Patents

Abstract

The invention discloses a leather protective coating agent which is prepared from the following raw materials, by weight, 35-50 parts of a modified cellulose nitrate emulsion, 25-35 parts of modified silicone oil, 5-15 parts of a thickening agent, 3-8 parts of polyacrylic acid, 10-15 parts of an antifoaming agent, 12-18 parts of 8% glacial acetic acid, 3-8 parts of a 10% sodium bicarbonate solution, 3-10 parts of an essence, 35-50 parts of absolute ethyl alcohol and 55-70 parts of deionized water; the invention also discloses a preparation method of the leather protection coating agent; the modified cellulose nitrate emulsion, the modified silicone oil, the polyacrylic acid, the 8% glacial acetic acid and the like are used as raw materials, and the modified cellulose nitrate emulsion has excellent stability and strong adhesive force, so that the coating agent can be endowed with good stability and adhesive property; the modified silicone oil prepared by the invention has good heat resistance and stability, and further endows the film coating agent with excellent heat resistance and stability.

Description

Leather protection coating agent and preparation method thereof

Technical Field

The invention belongs to the technical field of spray coating, and particularly relates to a leather protective coating agent and a preparation method thereof.

Background

The main material used in leather shoe production or leather garment and leather sofa production is leather (also called natural leather), which is made of animal leather and called natural leather (genuine leather). The leather is transformed into a fixed and durable substance, called leather, for short, after a series of physicochemical and mechanical processes in the tanning process. Leather is a product existing in early culture of human beings, belongs to a natural product, has limited sources and is more precious.

Leather care refers to a series of care operations for cleaning, maintaining, polishing, color-complementing, film-plating and the like of leather products, such as leather clothes, leather sofas, leather chairs, leather bags, leather shoes and the like. The existing leather coating agents used in the leather nursing process are mostly prepared from organic silicon emulsion or solid wax, and have the defects of no dryness, stickiness or too hard, easy cracking, difficult construction operation, no dirt resistance, non-lasting gloss and the like.

Chinese invention patent CN105803135A discloses a leather protection coating agent and a preparation method thereof. The coating agent comprises carnauba wax emulsion, polyurethane, organic silicon emulsion, a flatting agent, a penetrating agent and water. The leather protection coating agent has good dirt separation, water resistance and friction resistance; in addition, the leather protection coating agent can form a protective layer on the surface of leather, so that dirt can not be adhered easily, the cleaning is more labor-saving, and the service life of the leather is prolonged. However, the coating agent can cause environmental pollution, has certain corrosivity, and in addition, the organic silicon emulsion has short protection time and insufficient glossiness, and all prepared coating agents cannot meet the daily life requirements of people.

Disclosure of Invention

In order to overcome the technical problems, the invention provides a leather protection coating agent and a preparation method thereof. In the process of preparing the leather protection coating agent, the modified cellulose nitrate emulsion, the modified silicone oil, the polyacrylic acid, 8% glacial acetic acid and the like are used as raw materials, the absolute ethyl alcohol is used as a solvent to prepare the leather protection coating agent, and the modified cellulose nitrate emulsion has excellent stability and strong adhesive force, so that the coating agent can be endowed with good stability and adhesive property; according to the invention, the hydrogen-containing silicone oil is modified by preparing a compound mixed solution by using ethylene glycol dimethyl ether and absolute ethyl alcohol as mixed solvents, and the modified hydrogen-containing silicone oil has good heat resistance and stability, so that the coating agent is further endowed with excellent heat resistance and stability.

The purpose of the invention can be realized by the following technical scheme:

a leather protective coating agent is prepared from the following raw materials, by weight, 35-50 parts of a modified cellulose nitrate emulsion, 25-35 parts of modified silicone oil, 5-15 parts of a thickening agent, 3-8 parts of polyacrylic acid, 10-15 parts of an antifoaming agent, 12-18 parts of 8% glacial acetic acid, 3-8 parts of a 10% sodium bicarbonate solution, 3-10 parts of essence, 35-50 parts of absolute ethyl alcohol and 55-70 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a 70 ℃ water bath, magnetically stirring for 30min, adding a defoaming agent, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, uniformly stirring for 15min, and performing reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding a thickening agent and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Further, the modified cellulose nitrate emulsion is prepared from the following raw materials in parts by weight: 6-10 parts of cellulose nitrate, 5-8 parts of alkyd resin, 3-8 parts of tributyl citrate, 2-5 parts of polyvinylpyrrolidone, 30-40 parts of diethylene glycol alkyl ether, 18-25 parts of acetone and 3-5 parts of sodium laurate.

Further, the modified cellulose nitrate emulsion is prepared by the following method:

(1) adding cellulose nitrate and acetone into a three-neck flask, stirring at a constant speed until the cellulose nitrate is dissolved, adding diethylene glycol alkyl ether, heating in a water bath at 50 ℃, stirring at a rotating speed of 120r/min for 2h, adding tributyl citrate and alkyd resin, heating to 70 ℃, stirring at a constant speed for 30min, adding polyvinylpyrrolidone, continuing stirring for 15min to prepare a mixed emulsion A, and transferring the mixed emulsion A into a beaker for later use;

(2) adding sodium laurate and deionized water into a conical flask, stirring for 45min at the rotating speed of 180r/min to obtain emulsion B, magnetically stirring the mixed emulsion A at the rotating speed of 480r/min, heating to 55 ℃, adding the emulsion B into the mixed emulsion A, and adding the deionized water until an oil-in-water type emulsion is formed to obtain the modified cellulose nitrate emulsion.

The cellulose nitrate chain is composed of glucose anhydride cyclic residues and has certain rigidity, but the ether chain among the rings enables the chain to easily rotate, so that the main chain of the cellulose nitrate is between the two extreme ends of complete rigidity and complete flexibility, and belongs to a semi-rigid polymer chain, so that emulsion formed by the cellulose nitrate is easily whitened, the adhesive force is poor, and the finally prepared film coating agent has poor adhesive force, glossiness and appearance; according to the invention, cellulose nitrate is dissolved in acetone, a mixed system is formed by adding diethylene glycol alkyl ether and tributyl citrate, alkyd resin is added to modify the cellulose nitrate, then sodium laurate and deionized water are added, the surface tension of the solvent and the deionized water can be reduced by the sodium laurate, so that the solvent can be dispersed into tiny water drops in a water phase medium, the contact area of an oil phase and a water phase is increased, the stability of the mixed system is further enhanced, and then the deionized water is added until an oil-in-water emulsion is formed, so that the stable modified cellulose nitrate emulsion with strong adhesive force is finally prepared.

Further, the modified silicone oil is prepared from the following raw materials in parts by weight: 12-18 parts of hydroquinone, 5-15 parts of mellitic acid, 35-50 parts of absolute ethyl alcohol, 2-6 parts of cinnamic acid, 10-15 parts of hydrogen-containing silicone oil (with the hydrogen content of 1.5) and 8-15 parts of ethylene glycol dimethyl ether.

Further, the modified silicone oil is prepared by the following method:

(1) adding ethylene glycol dimethyl ether and hydroquinone into a three-neck flask, stirring at a constant speed for 10min, adding half of absolute ethyl alcohol, heating to 75 ℃, stirring at a constant speed for 15min, adding cinnamic acid, stirring at a rotating speed of 180r/min, heating to 110 ℃, reacting at the temperature for 2h, detecting the acid value every 30min, dropwise adding a 10% sodium hydroxide solution to adjust the pH value until the pH value is 7, separating, washing and drying to obtain a mixed solution;

(2) and (2) transferring the mixed solution prepared in the step (1) into a four-neck flask, adding the other half of absolute ethyl alcohol, stirring at a constant speed, heating to 65 ℃, keeping the temperature for 15min, adding mellitic acid, heating to 80 ℃, introducing nitrogen to discharge air, adding hydrogen-containing silicone oil, reacting for 5h at the temperature to test the hydrogen content, and removing the solvent in vacuum when the hydrogen content is stable to prepare the modified silicone oil.

The hydrogen-containing silicone oil has the characteristics of the dimethyl silicone oil, and can generate addition and crosslinking reactions due to the active hydrogen, so the hydrogen-containing silicone oil can participate in various chemical reactions, has good film-forming performance, but can react with hydroxyl radicals or alcoholic hydroxyl groups to release hydrogen, and has poor heat resistance compared with the dimethyl silicone oil, so that the coating agent prepared by taking the hydrogen-containing silicone oil as a raw material has poor heat resistance. According to the invention, mellitic acid and cinnamic acid are used as raw materials, glycol dimethyl ether and absolute ethyl alcohol are used as mixed solvents to prepare a compound mixed solution to modify hydrogen-containing silicone oil, hydroquinone is added to enhance the stability of the compound mixed solution, and the compound mixed solution can avoid side reaction generated by condensation of hydroxyl and a silicon hydrogen bond in the modification process of the finally prepared modified silicone oil.

Further, the thickening agent is one or more of starch, gelatin and sodium alginate.

Further, the defoaming agent is one or more of polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropylene amine ether and polyoxypropylene glycerol ether.

A preparation method of a leather protection coating agent comprises the following steps:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a 70 ℃ water bath, magnetically stirring for 30min, adding a defoaming agent, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, uniformly stirring for 15min, and performing reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding a thickening agent and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

The invention has the beneficial effects that:

(1) in the process of preparing the leather protection coating agent, the modified cellulose nitrate emulsion, the modified silicone oil, the polyacrylic acid, 8% glacial acetic acid and the like are used as raw materials, the absolute ethyl alcohol is used as a solvent to prepare the leather protection coating agent, and the modified cellulose nitrate emulsion has excellent stability and strong adhesive force, so that the coating agent can be endowed with good stability and adhesive property; according to the invention, the hydrogen-containing silicone oil is modified by preparing a compound mixed solution by using ethylene glycol dimethyl ether and absolute ethyl alcohol as mixed solvents, and the modified hydrogen-containing silicone oil has good heat resistance and stability, so that the coating agent is further endowed with excellent heat resistance and stability;

(2) because the effect of the single functional group after modification of the silicone oil is single, in the process of preparing the modified silicone oil, firstly, a compound mixed solution is prepared by taking ethylene glycol dimethyl ether and absolute ethyl alcohol as a mixed solvent, and hydroquinone is added to enhance the stability of the compound mixed solution, so that the adverse effect caused by unstable quality or difficult lasting finishing effect of the compound mixed solution is solved, and the film coating agent prepared by the modified silicone oil has excellent heat resistance and stability;

(3) the leather protection coating agent prepared by the invention can form a protective layer on the surface of leather, the protective layer is safe and nontoxic, cannot influence human bodies and the environment, cannot corrode the leather, has excellent stability and heat resistance, has high glossiness, and can meet the daily life requirements of people.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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

A leather protection coating agent is prepared from the following raw materials, by weight, 35 parts of modified cellulose nitrate emulsion, 25 parts of modified silicone oil, 5 parts of gelatin, 3 parts of polyacrylic acid, 10 parts of polyoxypropylene glycerol ether, 12 parts of 8% glacial acetic acid, 3 parts of 10% sodium bicarbonate solution, 3 parts of essence, 35 parts of absolute ethyl alcohol and 55 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

s4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and preparing the leather protection coating agent;

the modified cellulose nitrate emulsion is prepared by the following method:

(1) adding cellulose nitrate and acetone into a three-neck flask, stirring at a constant speed until the cellulose nitrate is dissolved, adding diethylene glycol alkyl ether, heating in a water bath at 50 ℃, stirring at a rotating speed of 120r/min for 2h, adding tributyl citrate and alkyd resin, heating to 70 ℃, stirring at a constant speed for 30min, adding polyvinylpyrrolidone, continuing stirring for 15min to prepare a mixed emulsion A, and transferring the mixed emulsion A into a beaker for later use;

(2) adding sodium laurate and deionized water into a conical flask, stirring for 45min at the rotating speed of 180r/min to obtain emulsion B, magnetically stirring the mixed emulsion A at the rotating speed of 480r/min, heating to 55 ℃, adding the emulsion B into the mixed emulsion A, and adding the deionized water until an oil-in-water type emulsion is formed to obtain a modified cellulose nitrate emulsion;

the modified silicone oil is prepared by the following method:

(1) adding ethylene glycol dimethyl ether and hydroquinone into a three-neck flask, stirring at a constant speed for 10min, adding half of absolute ethyl alcohol, heating to 75 ℃, stirring at a constant speed for 15min, adding cinnamic acid, stirring at a rotating speed of 180r/min, heating to 110 ℃, reacting at the temperature for 2h, detecting the acid value every 30min, dropwise adding a 10% sodium hydroxide solution to adjust the pH value until the pH value is 7, separating, washing and drying to obtain a mixed solution;

(2) and (2) transferring the mixed solution prepared in the step (1) into a four-neck flask, adding the other half of absolute ethyl alcohol, stirring at a constant speed, heating to 65 ℃, keeping the temperature for 15min, adding mellitic acid, heating to 80 ℃, introducing nitrogen to discharge air, adding hydrogen-containing silicone oil, reacting for 5h at the temperature to test the hydrogen content, and removing the solvent in vacuum when the hydrogen content is stable to prepare the modified silicone oil.

Example 2

The leather protective coating agent is prepared from the following raw materials, by weight, 40 parts of modified cellulose nitrate emulsion, 26 parts of modified silicone oil, 8 parts of gelatin, 5 parts of polyacrylic acid, 12 parts of polyoxypropylene glycerol ether, 14 parts of 8% glacial acetic acid, 5 parts of 10% sodium bicarbonate solution, 5 parts of essence, 40 parts of absolute ethyl alcohol and 60 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Example 3

45 parts of modified cellulose nitrate emulsion, 30 parts of modified silicone oil, 12 parts of gelatin, 6 parts of polyacrylic acid, 12 parts of polyoxypropylene glycerol ether, 16 parts of 8% glacial acetic acid, 6 parts of 10% sodium bicarbonate solution, 8 parts of essence, 45 parts of absolute ethyl alcohol and 65 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Example 4

A leather protection coating agent is prepared from the following raw materials, by weight, 50 parts of modified cellulose nitrate emulsion, 35 parts of modified silicone oil, 15 parts of gelatin, 8 parts of polyacrylic acid, 15 parts of polyoxypropylene glycerol ether, 18 parts of 8% glacial acetic acid, 8 parts of 10% sodium bicarbonate solution, 10 parts of essence, 50 parts of absolute ethyl alcohol and 70 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Comparative example 1

In this comparative example, cellulose nitrate was used in place of the modified cellulose nitrate emulsion as compared to example 1, and the preparation method was as follows:

step S1, adding cellulose nitrate into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as solution A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Comparative example 2

Compared with example 1, the preparation method of the comparative example, which replaces the modified silicone oil with the silicone oil, is as follows:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding silicone oil and deionized water into a three-neck flask, heating in a water bath at 70 ℃, magnetically stirring for 30min, adding polyoxypropylene glycerol ether, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, stirring at a constant speed for 15min, and carrying out reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding gelatin and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.

Comparative example 3

The comparative example is a leather protection coating agent in the market.

The gloss and the durability of examples 1 to 4 and comparative examples 1 to 3 were measured, and the results are shown in table 1 below;

gloss: according to GB/T9754-2007 determination of 20 degrees, 60 degrees and 85 degrees mirror gloss of colored paint films of colored paints and varnishes which do not contain metallic pigments, a piece of finished leather is taken, the leather protection coating agents prepared in examples 1-4 and comparative examples 1-3 are uniformly coated on the surface of the leather, air drying is carried out, and then the gloss of the surface of the leather at 20 degrees, 60 degrees and 85 degrees is tested;

the persistence degree is as follows: and (3) carrying out a rubbing color fastness test according to GB/T16799-.

TABLE 1

From Table 1 above, it can be seen that examples 1-4 are in the gloss test: the gloss at 20 ℃ is between 53 and 57, the gloss at 60 ℃ is between 63 and 66, and the gloss at 85 ℃ is between 79 and 83; comparative examples 1-3 in the gloss test: the gloss at 20 ℃ is between 35 and 45, the gloss at 60 ℃ is between 39 and 58, and the gloss at 85 ℃ is between 55 and 68; examples 1-4 in the persistence test: the dry wiping grade is 4-5 grades, and the wet wiping grade is 4-5 grades; comparative examples 1-3 in the durability test: the dry wiping grade is 2-3 grades, and the wet wiping grade is 2-3 grades. Therefore, the leather protection coating agent prepared by the invention not only has excellent stability and heat resistance, but also has higher glossiness, and can meet the requirements of people in daily life.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.

Claims (4)

1. The leather protection coating agent is characterized by being prepared from the following raw materials, by weight, 35-50 parts of modified cellulose nitrate emulsion, 25-35 parts of modified silicone oil, 5-15 parts of a thickening agent, 3-8 parts of polyacrylic acid, 10-15 parts of a defoaming agent, 12-18 parts of 8% glacial acetic acid, 3-8 parts of 10% sodium bicarbonate solution, 3-10 parts of essence, 35-50 parts of absolute ethyl alcohol and 55-70 parts of deionized water;

the leather protection coating agent is prepared by the following method:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a 70 ℃ water bath, magnetically stirring for 30min, adding a defoaming agent, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, uniformly stirring for 15min, and performing reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

s4, transferring the mixture to a dispersion kettle, adding a thickening agent and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and preparing the leather protection coating agent;

the modified silicone oil is prepared from the following raw materials in parts by weight: 12-18 parts of hydroquinone, 5-15 parts of mellitic acid, 35-50 parts of absolute ethyl alcohol, 2-6 parts of cinnamic acid, 10-15 parts of hydrogen-containing silicone oil and 8-15 parts of ethylene glycol dimethyl ether;

the modified silicone oil is prepared by the following method:

(1) adding ethylene glycol dimethyl ether and hydroquinone into a three-neck flask, stirring at a constant speed for 10min, adding half of absolute ethyl alcohol, heating to 75 ℃, stirring at a constant speed for 15min, adding cinnamic acid, stirring at a rotating speed of 180r/min, heating to 110 ℃, reacting at the temperature for 2h, detecting the acid value every 30min, dropwise adding a 10% sodium hydroxide solution to adjust the pH value until the pH value is stable, separating, washing and drying to obtain a mixed solution;

(2) transferring the mixed solution prepared in the step (1) into a four-neck flask, adding the other half of absolute ethyl alcohol, stirring at a constant speed, heating to 65 ℃, keeping the temperature for 15min, adding mellitic acid, heating to 80 ℃, introducing nitrogen to discharge air, adding hydrogen-containing silicone oil, reacting for 5h at the temperature to test the hydrogen content, and removing the solvent in vacuum when the hydrogen content is stable to prepare modified silicone oil;

the modified cellulose nitrate emulsion is prepared from the following raw materials in parts by weight: 6-10 parts of cellulose nitrate, 5-8 parts of alkyd resin, 3-8 parts of tributyl citrate, 2-5 parts of polyvinylpyrrolidone, 30-40 parts of diethylene glycol alkyl ether, 18-25 parts of acetone and 3-5 parts of sodium laurate;

the modified cellulose nitrate emulsion is prepared by the following method:

(1) adding cellulose nitrate and acetone into a three-neck flask, stirring at a constant speed until the cellulose nitrate is dissolved, adding diethylene glycol alkyl ether, heating in a water bath at 50 ℃, stirring at a rotating speed of 120r/min for 2h, adding tributyl citrate and alkyd resin, heating to 70 ℃, stirring at a constant speed for 30min, adding polyvinylpyrrolidone, continuing stirring for 15min to prepare a mixed emulsion A, and transferring the mixed emulsion A into a beaker for later use;

(2) adding sodium laurate and deionized water into a conical flask, stirring for 45min at the rotating speed of 180r/min to obtain emulsion B, magnetically stirring the mixed emulsion A at the rotating speed of 480r/min, heating to 55 ℃, adding the emulsion B into the mixed emulsion A, and adding the deionized water until an oil-in-water type emulsion is formed to obtain the modified cellulose nitrate emulsion.

2. The leather protective coating agent of claim 1, wherein the thickening agent is one or more of starch, gelatin and sodium alginate.

3. The coating agent for leather protection as claimed in claim 1, wherein the defoaming agent is one or more of polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropylene amine ether and polyoxypropylene glycerol ether.

4. The method for preparing the leather protective coating agent according to claim 1, characterized by comprising the following steps:

step S1, adding the modified cellulose nitrate emulsion into a beaker filled with absolute ethyl alcohol, heating in a water bath at 45 ℃, stirring at a constant speed for 25min, adding 8% glacial acetic acid, heating to 60 ℃, and stirring for 5min to serve as liquid A for later use;

step S2, adding modified silicone oil and deionized water into a three-neck flask, heating in a 70 ℃ water bath, magnetically stirring for 30min, adding a defoaming agent, heating to 75 ℃, keeping the temperature for 2h, adding polyacrylic acid, uniformly stirring for 15min, and performing reflux reaction for 1h to obtain solution B;

step S3, pouring the solution B into the solution A, stirring at a constant speed for 5min, adding 10% sodium bicarbonate solution, heating to 50 ℃, reacting for 2h at the temperature to obtain a mixed solution, performing ultrasonic treatment for 30min, dispersing the mixed solution by using a dispersion machine, and controlling the rotation speed of the dispersion machine to be 500r/min and the dispersion time to be 50 min;

and step S4, transferring the mixture to a dispersion kettle, adding a thickening agent and essence, heating to 75 ℃, continuing stirring and dispersing, controlling the dispersion speed to be 2000r/min and the dispersion time to be 1h, and obtaining the leather protection coating agent.