Weather-resistant polyisocyanate modified acrylic resin and preparation method thereof

Abstract

The weather-resistant polyisocyanate modified acrylic resin is prepared from 17%-21% of methyl methacrylate, 5%-9% of hydroxyethyl acrylate, 9%-13% of butyl acrylate, 5%-9% of styrene, 0.5%-2.5% of acrylic acid, 0.3%-1.5% of a dicumyl peroxide (DCP) initiator, 42%-46% of a xylene solvent and the balance of water. And 8%-12% of HDI (hexamethylene diisocyanate). According to the experiment, the optimal raw material composition and proportion are obtained through screening of a large number of experiments, the optimal synthesis process is obtained through optimization of a large number of experiments, and the conversion rate reaches up to 99.7%. The prepared modified acrylic resin has excellent weather resistance, meanwhile, a coating film has the advantages of wear resistance, water resistance, solvent resistance and the like, heat resistance, gloss retention and flexibility can be improved by using fat polyisocyanates such as biuret of HDI, and a very good technical effect is achieved in comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the technical field of resins, and specifically relates to a weather-resistant polyisocyanate-modified acrylic resin, which has excellent weather resistance, and the coating film has comprehensive properties such as wear resistance, water resistance, solvent resistance, heat resistance, gloss retention, good flexibility, etc. Background Art

[0002] Acrylic resin has the characteristics of good transparency, bright color, good adhesion and good toughness, and is widely used in coating materials. However, in certain environments, the use of ordinary acrylic resin has certain performance defects, mainly in terms of water resistance, anti-fouling performance, weather resistance, etc., which affects the development and application of acrylic resin. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to optimize the composition of acrylic resin monomer and initiator and add HDI (hexamethylene diisocyanate) to prepare acrylic resin with excellent weather resistance. At the same time, the coating film has excellent comprehensive properties such as wear resistance, water resistance, solvent resistance, heat resistance, gloss retention and good flexibility.

[0004] Technical solution, in order to achieve the above purpose, the technical solution adopted by the present invention is:

[0005] A weather-resistant polyisocyanate-modified acrylic resin is prepared from the following raw materials: methyl methacrylate, ethyl acrylate, butyl acrylate, styrene, acrylic acid, an initiator, xylene, and hexamethylene diisocyanate (HDI);

[0006] As a preferred embodiment, the weather-resistant polyisocyanate-modified acrylic resin is made of the following raw materials in percentage by mass:

[0007] 17%-21% methyl methacrylate, 5%-9% hydroxyethyl acrylate, 9%-13% butyl acrylate, 5%-9% styrene, 0.5%-2.5% acrylic acid, 0.3%-1.5% initiator, 42%-46% xylene solvent, 8%-12% hexamethylene diisocyanate (HDI);

[0008] As a preferred embodiment, the weather-resistant polyisocyanate-modified acrylic resin described above is made of the following raw materials in percentage by mass: 19.2% methyl methacrylate, 7.2% hydroxyethyl acrylate, 11% butyl acrylate, 6.9% styrene, 0.5% acrylic acid, 0.6% initiator, 44.3% xylene solvent, and 10.3% hexamethylene diisocyanate (HDI).

[0009] As a preferred embodiment, the weather-resistant polyisocyanate-modified acrylic resin described above, the initiator is DCP (diisopropylbenzene peroxide)

[0010] The method for preparing a weather-resistant polyisocyanate-modified acrylic resin of the present invention comprises the following steps:

[0011] (1) Adding xylene solvent into a reaction apparatus and heating to reflux;

[0012] (2) Methyl methacrylate, hydroxyethyl acrylate, butyl acrylate, styrene, acrylic acid and initiator are mixed evenly and added into a dropping funnel;

[0013] (3) When the temperature of the reaction device in step (1) reaches the reflux temperature, the mixture in step (2) is added dropwise, and after the addition is completed, the mixture is refluxed and kept warm for a period of time. After the temperature is lowered, hexamethylene diisocyanate (HDI) is added and stirred to obtain the product.

[0014] As a preferred embodiment, in the above-mentioned weather-resistant polyisocyanate-modified acrylic resin, the initiator is DCP (dicumyl peroxide).

[0015] As a preferred embodiment, in the above-mentioned method for preparing a weather-resistant polyisocyanate-modified acrylic resin, the HDI (hexamethylene diisocyanate) has good weather resistance.

[0016] As a preferred embodiment, a method for preparing a weather-resistant polyisocyanate-modified acrylic resin is characterized in that, in step (3), when the temperature of the reaction device in step (1) reaches reflux, preparation for dropwise addition is started, the mixture of step (2) is added dropwise, and the dropwise addition is completed within 4.5 hours. After the dropwise addition is completed, the mixture is kept warm for 2 hours, cooled to 80°C, HDI is added, and stirred for 15 minutes to obtain the product.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0018] The present invention selects and adjusts the best acrylic resin monomer, polyisocyanate and initiator system composition through a large number of experimental screenings. The present invention selects HDI (hexamethylene diisocyanate) and initiator DCP (diisopropylbenzene peroxide) at a relatively high reaction temperature of 128-138°C, and a relatively long dropwise addition time and a method of heat preservation again after adding the initiator to make the resin have a high conversion rate of 99.7%. The acrylic resin prepared by the present invention has excellent weather resistance, and the coating film has the advantages of wear resistance, water resistance, solvent resistance, etc. The use of fatty polyisocyanates such as biuret of HDI can increase the comprehensive properties such as heat resistance, light retention, and flexibility. DETAILED DESCRIPTION

[0019] Example 1

[0020] 1. A weather-resistant polyisocyanate-modified acrylic resin, which is made of the following raw materials in percentage by mass: 19.2% methyl methacrylate, 7.2% hydroxyethyl acrylate, 11% butyl acrylate, 6.9% styrene, 0.5% acrylic acid, 0.6% DCP initiator, 44.3% xylene solvent, and 10.3% HDI (hexamethylene diisocyanate).

[0021] 2. The method for preparing a weather-resistant polyisocyanate-modified acrylic resin of the present invention comprises the following steps:

[0022] (1) Add 295.8 g of xylene into a reaction apparatus and heat to reflux at 128° C.

[0023] (2) 128 g of methyl methacrylate, 48 g of hydroxyethyl acrylate, 73.3 g of butyl acrylate, 46.3 g of styrene, 3.2 g of acrylic acid, and 4.5 g of initiator DCP (dicumyl peroxide) were mixed evenly and added to a dropping funnel;

[0024] (3) When the temperature of the reaction device in step (1) reaches the reflux temperature of 128°C, the mixture in step (2) is added dropwise, and the addition is completed in 4.5 hours. After the addition is completed, the mixture is refluxed and kept warm for 2 hours, cooled to 80°C, and 69 g of HDI is added and stirred for 15 minutes to obtain the final reaction. The conversion rate of the final reaction can reach 99.7%, and the resin solid content is 55.5%.

[0025] The weather-resistant polyisocyanate-modified acrylic resin was mixed with the various ingredients in Table 1 below in proportion, stirred for 30 minutes with a high-speed disperser to prepare an acrylic resin industrial paint, sprayed on an iron plate, and baked at 160°C for 20 minutes. The paint film was 25 microns. The test performance is shown in Table 2.

[0026] Table 1: Composition of acrylic resin industrial paint formula

[0027] Raw material name Weight(g) Example 1 Acrylic resin 54 Dimethylethanolamine (DMEA) 3.8 A010 dispersant 0.5 Titanium dioxide 36 Xylene 11 Amino for baking varnish(5747) 5

[0028] Table 2 Paint film performance test results

[0029] Appearance Smooth and particle-free Hardness (pencil scratch) 4H Impact (recoil) (kg.cm) 50 Adhesion (circle method) Level 1 luster 96 Boil for 24 hours (40℃) qualified Solvent resistant wipe (alcohol) 1000 times

[0030] The hardness (pencil scratch) is measured according to GB / T6739-1996 Determination of pencil hardness of coating film; the impact (recoil) is measured according to GBT1732-93 Determination of impact resistance of paint film; the adhesion (circle scratch method) is measured according to GB / T1720-79(89) Determination of adhesion of paint film; the gloss is measured according to GB / T 9754-2007 Determination of 20°, 60° and 85° specular gloss of paints and varnishes without metallic pigments (60° shall prevail).

[0031] The above experimental results show that the present invention screened out various reaction raw material compositions through a large number of experiments, especially the HDI (hexamethylene diisocyanate) selected by the present invention, the initiator is DCP (diisopropylbenzene peroxide), and the resin has a high conversion rate of 99.7% at a relatively high reaction temperature of 128°C, a relatively long dropwise addition time, and a method of heat preservation again after adding the initiator. The acrylic resin prepared by the present invention has excellent weather resistance, and the coating film has the advantages of wear resistance, water resistance, solvent resistance, etc. The use of fatty polyisocyanates such as biuret of HDI can increase the comprehensive properties such as heat resistance, light retention, and flexibility.

[0032] Comparative Example 1

[0033] A method for preparing an acrylic resin comprises the following steps:

[0034] (1) Add 243.2 g of xylene into the reaction apparatus and heat to reflux at 128°C;

[0035] (2) 128 g of methyl methacrylate, 48 g of hydroxyethyl acrylate, 73.3 g of butyl acrylate, 46.3 g of styrene, 3.2 g of acrylic acid, and 4.5 g of initiator DCP (dicumyl peroxide) were mixed evenly and added to a dropping funnel;

[0036] (3) When the temperature of the reaction device in step (1) reaches the reflux temperature of 128°C, the mixture in step (2) is added dropwise, and the mixture is added dropwise for 4.5 hours. After the addition is completed, the mixture is refluxed and kept warm for 2 hours to obtain the final reaction. The conversion rate can reach 97.4%, and the resin solid content is 54.1%.

[0037] The prepared acrylic resin and the various ingredients in Table 3 below were mixed in proportion, stirred with a high-speed disperser for 30 minutes to prepare acrylic resin industrial baking paint, sprayed on the iron plate, baked at 160°C for 20 minutes, and the paint film was 25 microns. The test performance is shown in Table 4.

[0038] Table 3 Composition of acrylic resin industrial paint formula

[0039] Raw material name Weight(g) Example 2 Acrylic resin 54 Dimethylethanolamine (DMEA) 3.8 A010 dispersant 0.5 Titanium dioxide 36 Xylene 11 Amino for baking varnish(5747) 5

[0040] Table 4 Paint film performance test results

[0041] Appearance Smooth and particle-free Hardness (pencil scratch) 4H Impact (recoil) (kg.cm) 30 Adhesion Level 2 luster 94 Boil for 24 hours (40℃) qualified Solvent resistant wipe (alcohol) 800 times

[0042] The hardness (pencil scratch) is measured according to GB / T6739-1996 Determination of pencil hardness of coating film; the impact (recoil) is measured according to GBT1732-93 Determination of impact resistance of paint film; the adhesion (circle scratch method) is tested according to GB / T1720-79 (89) Determination of adhesion of paint film; the gloss is measured according to GB / T 9754-2007 Determination of 20°, 60° and 85° specular gloss of paints and varnishes without metallic pigments (60° shall prevail).

[0043] Comparative Example 2

[0044] A method for preparing an acrylic resin comprises the following steps:

[0045] (1) Add 295.8 g of xylene into a reaction apparatus and heat to reflux at 128° C.

[0046] (2) 128 g of methyl methacrylate, 48 g of hydroxyethyl acrylate, 73.3 g of butyl acrylate, 46.3 g of styrene, 3.2 g of acrylic acid, and 4.5 g of initiator TBPB (tert-butyl benzoyl peroxide) were mixed evenly and added to a dropping funnel;

[0047] (3) When the temperature of the reaction device in step (1) reaches the reflux temperature of 128°C, the mixture in step (2) is added dropwise, and the mixture is added dropwise for 4.5 hours. After the addition is completed, the mixture is refluxed and kept warm for 2 hours, cooled to 80°C, and 50 g of HDI is added and stirred for 15 minutes to obtain the final reaction. The conversion rate of the final reaction can reach 95.2%, and the resin solid content is 53%.

[0048] The obtained acrylic resin was mixed with the various ingredients in Table 5 below in proportion, stirred with a high-speed disperser for 30 minutes to make an acrylic resin industrial paint, sprayed on the iron plate, and baked at 160°C for 20 minutes. The paint film was 25 microns. The test performance is shown in Table 6.

[0049] Table 5: Composition of acrylic resin industrial paint formula

[0050] Raw material name Weight(g) Example 3 Acrylic resin 54 Dimethylethanolamine (DMEA) 3.8 A010 dispersant 0.5 Titanium dioxide 36 Xylene 11 Amino for baking varnish(5747) 5

[0051] Table 6 Paint film performance test results

[0052]

[0053]

[0054] Example 2 Performance Comparison Test

[0055] The plate paint films prepared in Example 1, Comparative Example 1 and Comparative Example 2 were subjected to a weathering test, and the test sample data was 1500 hours (placed in an ultraviolet accelerated aging tester LU-8047-TM, adjusted to 340 light aging). The test results are shown in Table 5 below.

[0056] Table 5

[0057]

[0058] The test results in Table 5 above show that the modified acrylic resin industrial baking varnish prepared by the formula of Example 1 of the present invention has better weather resistance and achieves good technical effects.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A weather-resistant polyisocyanate-modified acrylic resin, characterized in that: It is made from the following raw materials: methyl methacrylate, hydroxyethyl acrylate, butyl acrylate, styrene, acrylic acid, initiator, xylene and hexamethylene diisocyanate.

2. A weather-resistant polyisocyanate-modified acrylic resin according to claim 1, characterized in that: The invention is prepared from the following raw materials in percentage by mass: 17%-21% of methyl methacrylate, 5%-9% of hydroxyethyl acrylate, 9%-13% of butyl acrylate, 5%-9% of styrene, 0.5%-2.5% of acrylic acid, 0.3%-1.5% of initiator, 42%-46% of xylene and 8%-12% of hexamethylene diisocyanate.

3. A weather-resistant polyisocyanate-modified acrylic resin according to claim 1, characterized in that: The invention is prepared from the following raw materials in percentage by mass: 19.2% of methyl methacrylate, 7.2% of hydroxyethyl acrylate, 11% of butyl acrylate, 6.9% of styrene, 0.5% of acrylic acid, 0.6% of initiator, 44.3% of xylene and 10.3% of hexamethylene diisocyanate.

4. A weather-resistant polyisocyanate-modified acrylic resin according to any one of claims 1 to 3, characterized in that: The initiator is DCP (dicumyl peroxide).

5. The method for preparing a weather-resistant polyisocyanate-modified acrylic resin according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Adding xylene solvent into a reaction apparatus and heating to reflux; (2) Methyl methacrylate, hydroxyethyl acrylate, butyl acrylate, styrene, acrylic acid and initiator are mixed evenly and added into a dropping funnel; (3) When the temperature of the reaction device in step (1) reaches the reflux temperature, start to dropwise add the mixture in step (2). After the dropwise addition is completed, reflux and keep the temperature for a period of time, cool down, add hexamethylene diisocyanate, stir, and obtain the product.

6. The method for preparing a weather-resistant polyisocyanate-modified acrylic resin according to claim 5, characterized in that: The initiator is DCP (dicumyl peroxide).

7. The method for preparing a weather-resistant polyisocyanate-modified acrylic resin according to claim 5, characterized in that: In step (3), when the temperature of the reaction device in step (1) reaches reflux, the mixture of step (2) is added dropwise, and the addition is completed in 4.5 hours. After the addition is completed, reflux is maintained for 2 hours, the temperature is lowered to 80° C., hexamethylene diisocyanate is added, and the mixture is stirred for 15 minutes to obtain the product.

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