CN115215789A

CN115215789A - Special anti-aging auxiliary agent for polyurethane coating and preparation method thereof

Info

Publication number: CN115215789A
Application number: CN202210908279.8A
Authority: CN
Inventors: 张强; 俞秀丽; 房超; 刘旭; 谢胜利; 项然
Original assignee: Suqian Liansheng Auxiliaries Co ltd
Current assignee: Suqian Liansheng Auxiliaries Co ltd
Priority date: 2022-07-29
Filing date: 2022-07-29
Publication date: 2022-10-21

Abstract

The invention relates to a preparation method of an anti-aging auxiliary agent special for polyurethane coating, which comprises the steps of carrying out ester exchange reaction on methyl carbamate and tetramethyl piperidinol to obtain a target product (a low molecular weight light stabilizer), wherein the product can be used as a novel light stabilizer applied to the polyurethane coating; the preparation method of the hindered amine light stabilizer is easy to prepare, relatively simple in synthesis process, good in compatibility with polyurethane coating and not easy to precipitate.

Description

Special anti-aging auxiliary agent for polyurethane coating and preparation method thereof

Technical Field

The invention belongs to the field of high polymer material auxiliaries, and particularly relates to an anti-aging auxiliary special for a polyurethane coating and a preparation method thereof.

Background

Polyurethane coatings are a common class of coatings and can be divided into two-component polyurethane coatings and one-component polyurethane coatings. Two-component polyurethane coatings are generally composed of two parts, usually referred to as a hardener component and a base component, of an isocyanate prepolymer (also called a low molecular urethane polymer) and a hydroxyl group-containing resin. The paint has a plurality of varieties and wide application range, and can be divided into acrylic polyurethane, alkyd polyurethane, polyester polyurethane, polyether polyurethane, epoxy polyurethane and the like according to the difference of hydroxyl-containing components. Generally has good mechanical properties, higher solid content and better properties in all aspects. Is a kind of paint with a great development prospect. The main application directions are wood coatings, automobile repairing coatings, anticorrosive coatings, floor coatings, electronic coatings, special coatings, polyurethane waterproof coatings and the like. The disadvantages are that the construction process is complex, the requirement on the construction environment is high, and the paint film is easy to generate defects. The single-component polyurethane coating mainly comprises urethane oil coating, moisture curing polyurethane coating, closed polyurethane coating and the like. The coating has a wider application range than a two-component coating, is mainly used for floor coatings, anticorrosive coatings, pre-roll coatings and the like, and has less overall performance than the two-component coating.

Carbamates are compounds in which an amino group or an amine group is directly attached to the carbonyl group of a formate. Also known as the monoester monoamide of carbonic acid. Carbamates can be prepared by reacting a chloroformate with ammonia or an amine, or by reacting a carbamoyl chloride with an alcohol or a phenol. The reaction of isocyanates with alcohols or phenols is also a simple process for the preparation of carbamates. Carbamates are an important class of organic synthetic reagents and raw materials for the manufacture of pharmaceuticals.

The weather resistance of the coating refers to the ability of the coating to maintain its original properties under the action of external environment (sunlight, air, water, condensation, industrial gases, microorganisms), and the coating may be irreversibly damaged by the external environment during use, such as: discoloration, loss of gloss, chalking, cracking, rusting, flaking, spotting, staining, and the like. Buildings, automobiles, steel structures and the like exposed to the outdoors gradually attract attention of people and become a focus of attention due to huge losses caused by aging damage such as discoloration, pulverization, peeling and the like of external coatings every year. Therefore, the weather resistance of the coating is important for the quality of the coating.

The reasons for the aging of the coating include internal and external factors, the internal factors are related to the type of film forming material of the coating and the used raw materials such as pigments, fillers, additives and the like, and are also greatly related to the formula system of the coating. The external cause of the aging of the coating refers to the exposure of the coating to the outdoor environment and the action of various destructive factors, mainly sunlight, rainwater, condensation, air temperature, oxygen, mold, industrial gas and the like.

The hindered amine light stabilizer is an organic amine compound with steric hindrance, has good inhibition effect on the photo-oxidative degradation reaction of high polymers and organic compounds, and is a light stabilizer with excellent performance. The hindered amine and the ultraviolet stabilizer have different action modes, and inhibit the photo-oxidative degradation reaction through various ways such as capturing free radicals, decomposing hydroperoxide and transferring the energy of excited molecules. The light stabilizing effect of the hindered amine on plastics is 2 to 4 times that of other ultraviolet stabilizers.

The catalyst used in the ester exchange method is mainly inorganic acid, organic acid or acid salt thereof traditionally, and has the advantage of low price. However, they are highly corrosive and have severe requirements for equipment, equipment and operating conditions. And the reaction time is long, the side reactions are more, the three wastes are serious, and the color and luster of the product are easy to deepen. This type of catalyst will be phased out in the transesterification process. Non-acidic catalysts are a new direction of development in recent years. It features no corrosion, high quality of product, light colour, less by-effect and mild reaction condition. At present, organotin compounds, titanic acid compounds and alkali metal alkoxide compounds are relatively ideal catalysts for the ester exchange process, and are widely used in industrial production in the future as long as the problem of recycling is solved.

Disclosure of Invention

In order to solve the problems, the invention discloses a preparation method of a hindered amine light stabilizer which is easy to prepare, has relatively simple synthesis process, better compatibility with polyurethane coating and difficult precipitation.

In order to achieve the purpose, the technical scheme of the invention is as follows:

the invention relates to an anti-aging auxiliary agent special for polyurethane coating and a preparation method thereof.

The reaction equation of the preparation method is as follows:

。

the method specifically comprises the following steps:

(1) Heating and stirring methyl carbamate and a solvent;

(2) Adding tetramethyl piperidinol and a catalyst into the reactant in the step (1), raising the reaction temperature to 80-130 ℃, and reacting to obtain the special anti-aging auxiliary agent for the polyurethane coating.

Further, in the step (1), the molar ratio of the methyl carbamate to the solvent is 1.

Further, the solvent is one of toluene, n-octane or petroleum ether.

Further, in the step (1), the heating temperature is 60-100 ℃, the stirring speed is 50-200r/min, and the stirring reaction time is 5-30min.

Further, in the step (2), the molar ratio of the tetramethylpiperidinol to the methyl carbamate is 1.12:1, the amount of the catalyst is 1 percent of that of the methyl carbamate.

Further, in the step (2), the catalyst is aluminum isopropoxide.

Further, in the step (2), the reaction time is 6-12h

The invention has the beneficial effects that:

the hindered amine light stabilizer has the advantages of less synthesis steps, mild reaction conditions and good compatibility of a product and the polyurethane coating, so that the processing performance and the anti-aging effect of the coating are excellent, and the anti-aging effect of the polyurethane coating can be effectively improved.

Drawings

FIG. 1 is an IR spectrum of the product of example 6.

Detailed Description

The present invention will be further illustrated with reference to the accompanying drawings and specific embodiments, which are to be understood as merely illustrative of the invention and not as limiting the scope of the invention.

Example 1

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam device, a return pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 ℃, adding 176g of tetramethyl piperidinol, starting stirring, reacting at 90 ℃ for 8 hours, cooling to room temperature, washing with water, decolorizing, and filtering to obtain 196.2g of target product with the yield of 78.1%.

Example 2

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam killer, a reflux pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 ℃, adding 176g of tetramethyl piperidinol, starting stirring, reacting at 100 ℃ for 8 hours, cooling to room temperature, washing with water, decolorizing, and filtering to obtain 205.1g of target product with the yield of 81.7%.

Example 3

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam device, a return pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 ℃, adding 176g of tetramethyl piperidinol, starting stirring, reacting at 110 ℃ for 8 hours, cooling to room temperature, washing with water, decolorizing, and filtering to obtain 206.8g of target product with the yield of 82.4%.

Example 4

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam killer, a reflux pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 ℃, adding 176g of tetramethyl piperidinol, starting stirring, reacting at 120 ℃ for 8h, cooling to room temperature, washing with water, decolorizing, and filtering to obtain 212.3g of target product with the yield of 84.6%.

Example 5

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam killer, a reflux pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 ℃, adding 176g of tetramethyl piperidinol, starting stirring, reacting at 120 ℃ for 10 hours, cooling to room temperature, washing with water, decolorizing, and filtering to obtain 218.5g of target product with the yield of 87.1%.

Example 6

460g of toluene as a solvent and 75g of methyl carbamate are added into a 1000ml four-mouth bottle formed by assembling a condenser, a water separator, a foam killer, a reflux pipe, a thermometer and a stirrer, stirring is started, and stirring is carried out at 80 ℃ and 100r/min for 30min. Cooling to 30 deg.C, adding 176g tetramethyl piperidinol, stirring, reacting at 130 deg.C for 12 hr, cooling to room temperature, washing with water, decolorizing, and filtering to obtain target product 228.9g with yield of 91.2%, and its infrared chromatogram is shown in FIG. 1.

Performance test data comparing the addition of 5% of the product of the example to 5% 292 of aging are shown in table 1.

Table 1 table of performance testing data

It should be noted that the above-mentioned contents only illustrate the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and it is obvious to those skilled in the art that several modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations fall within the protection scope of the claims of the present invention.

Claims

1. The special anti-aging auxiliary agent for the polyurethane coating is characterized by having the following structural formula:

。

2. the preparation method of the special anti-aging auxiliary agent for the polyurethane coating as claimed in claim 1, wherein the reaction equation of the preparation method is as follows:

。

3. the preparation method of the special anti-aging additive for the polyurethane coating as claimed in claim 2, wherein the preparation method specifically comprises the following steps:

(1) Heating and stirring methyl carbamate and a solvent;

(2) Adding tetramethylpiperidinol and a catalyst into the reactant in the step (1), raising the reaction temperature to 80-130 ℃, and reacting to obtain the special anti-aging auxiliary agent for the polyurethane coating.

4. The preparation method of the special anti-aging auxiliary agent for polyurethane coating according to claim 3, wherein in the step (1), the molar ratio of the methyl carbamate to the solvent is 1.

5. The preparation method of the special anti-aging auxiliary agent for the polyurethane coating as claimed in claim 4, wherein the solvent is one of toluene, n-octane or petroleum ether.

6. The preparation method of the anti-aging auxiliary agent special for polyurethane coating according to claim 3, wherein in the step (1), the heating temperature is 60-100 ℃, the stirring speed is 50-200r/min, and the stirring reaction time is 5-30min.

7. The preparation method of the anti-aging additive special for polyurethane coating as claimed in claim 3, wherein in the step (2), the molar ratio of the tetramethylpiperidinol to the methyl carbamate is 1.12:1, the amount of the catalyst is 1 percent of that of the methyl carbamate.

8. The preparation method of the special anti-aging auxiliary agent for the polyurethane coating as claimed in claim 3, wherein in the step (2), the catalyst is aluminum isopropoxide.

9. The preparation method of the special anti-aging auxiliary agent for polyurethane coating as claimed in claim 3, wherein in the step (2), the reaction time is 6-12h.