A photosensitive dodecafunctional polyester acrylate and preparation method thereof

Abstract

This invention discloses a method for preparing a photosensitive dodecyl polyester acrylate. First, terephthaloyl chloride and citric acid react to obtain an intermediate I with six terminal carboxyl groups. Then, this intermediate reacts with glycerol to obtain a two-step intermediate II with twelve terminal hydroxyl groups. Finally, intermediate II is reacted with acrylic acid and trimethylolethane polyglycidyl ether under specific reaction conditions to obtain the final reaction product. This invention, through extensive experimental screening, has obtained the optimal raw material composition and ratio, resulting in a photosensitive dodecyl polyester acrylate with a scientifically reasonable component ratio, good stability, low viscosity, fast curing speed, and high film hardness.

Description

Technical Field

[0001] The invention relates to an oligomer for photosensitive coatings, in particular to a photosensitive dodecafunctional polyester acrylate and a preparation method thereof, belonging to the technical field of polymer materials. Background Art

[0002] UV curing is a material surface treatment technology that appeared in the 1960s. It uses ultraviolet light to trigger the rapid polymerization and cross-linking of chemically active liquid materials, and instantly solidifies them into solid materials with certain properties. This technology has always been characterized by high efficiency, energy saving, and high quality. As early as 1952, Flory had proposed that highly branched polymers could be prepared from fluoropolymer monomers, and by the mid-1980s, researchers at DuPont purposefully synthesized a hyperbranched polymer. The highly branched three-dimensional macromolecular structure has many branching points, a spherical and compact molecular structure, a small hydrodynamic radius of gyration, molecular chains that are not easy to entangle, and viscosity that does not change with the increase of molecular weight. It has been widely concerned by scientific researchers because of its rich terminal functional groups and easy modification. Due to its special properties, it has applications in a variety of systems such as high-solid coatings, photocurable coatings, and powder coatings.

[0003] The invention develops a photosensitive dodecafunctional polyester acrylate with good stability, low viscosity, fast curing speed and high paint film hardness through a large number of experimental screenings and selection of the dosage of terephthaloyl chloride, citric acid, glycerol and acrylic acid and selection of synthesis conditions. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to select terephthaloyl chloride and citric acid to obtain an intermediate with six terminal carboxyl groups through a certain reaction temperature and reaction time, then react the intermediate with glycerol to obtain a two-step intermediate with twelve terminal hydroxyl groups, and finally react the two-step intermediate with acrylic acid and trimethylolethane polyglycidyl ether under certain reaction conditions to obtain the final reaction product. The present invention can be widely used in various photocurable coating systems that require high reactivity and low viscosity, and can solve the shortcomings of the prior art.

[0005] Another object of the present invention is to provide a preparation method of the photosensitive dodecafunctional polyester acrylate and its basic application performance.

[0006] Technical solution, in order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a photosensitive dodecafunctional polyester acrylate comprises the following steps:

[0008] (1) First, terephthaloyl chloride and citric acid are reacted under certain reaction conditions to obtain an intermediate I having six terminal carboxyl groups;

[0009] (2) then reacting the intermediate I with propylene glycol under certain conditions to obtain an intermediate II having twelve hydroxyl groups at the end;

[0010] (3) Finally, the intermediate II is further reacted with acrylic acid and trimethylolethane polyglycidyl ether under certain reaction conditions to obtain a photosensitive dodecafunctional polyester acrylate.

[0011] As a preferred embodiment, the method for preparing the photosensitive dodecafunctional polyester acrylate of the present invention comprises the following steps:

[0012] (1) firstly selecting 5-15 parts by weight of terephthaloyl chloride and 10-30 parts by weight of citric acid to prepare an intermediate I having six terminal carboxyl groups through certain reaction conditions;

[0013] (2) then reacting the intermediate I with 10-30 parts by weight of propylene glycol under certain conditions to obtain an intermediate II having twelve hydroxyl groups at the end;

[0014] (3) Finally, the intermediate II is further reacted with 25-50 parts by weight of acrylic acid and 0.5-3 parts by weight of trimethylolethane polyglycidyl ether under certain reaction conditions to obtain a photosensitive dodecafunctional polyester acrylate.

[0015] As a preferred embodiment, the above step (1) is to dissolve terephthaloyl chloride in 6.5 parts by mass of toluene, and slowly add the solution dropwise to 6.5 parts by mass of toluene in which citric acid has been dissolved. While adding the solution dropwise, a slight vacuum of -0.005 to -0.01 MPa is used to remove the acid mist generated by the reaction. The adding time is 1 to 8 hours. After the adding is completed, the reaction is continued under vacuum. The reaction temperature is controlled between -10°C and 30°C. The reaction time is 5 to 12 hours. After the reaction is completed, the temperature is lowered to obtain an intermediate I with six terminal carboxyl groups.

[0016] As a preferred embodiment, the above step (2) is to add propylene glycol to intermediate I, and then add 0-0.5 parts by mass of an antioxidant hypophosphorous acid and 0-0.5 parts by mass of a catalyst p-toluenesulfonic acid, control the reaction time to be 5 to 10 hours, and the reaction temperature to be 110°C to 160°C. When the acid value is lower than 3 mgKOH / g, the reaction is terminated by cooling to obtain intermediate II.

[0017] As a preferred solution, the above step (3) is to add acrylic acid to the intermediate II, and then add 0-0.5 parts by weight of hypophosphorous acid as an antioxidant, 0-0.5 parts by weight of hydroquinone as an inhibitor and 0-1 parts by weight of p-toluenesulfonic acid as a catalyst, control the reaction time to be 5 to 10 hours, and the reaction temperature to be 90°C to 130°C. When the acid value is lower than 10 mgKOH / g, the temperature is lowered to below 80°C, trimethylolethane polyglycidyl ether and 0-0.5 parts by weight of benzyltriethylammonium chloride as a catalyst are added, and the reaction time is controlled to be 1-3 hours, and the reaction temperature is 90-130°C. After the reaction is completed, a vacuum of -0.1 MPa is opened, and the solvent is removed for 1 to 3 hours to obtain the final product, photosensitive twelve-official polyester acrylate.

[0018] The present invention focuses on the need to strictly control the vacuum environment when synthesizing intermediate I. Since the reaction has a certain reversible tendency, when controlling a certain vacuum environment, the hydrochloric acid mist generated by the positive reaction can be timely removed while the solvent in the system is not removed, thereby obtaining an intermediate I with six terminal carboxyl groups (otherwise, 6 terminal carboxyl groups cannot be obtained). In the synthesis of intermediate II, glycerol with inconsistent hydroxyl activity is selected to participate in the reaction. Since the electron-pushing effect of the intermediate carbon atom is the strongest, the reaction activity of the intermediate participating in the esterification reaction is the strongest. It is necessary to strictly control the reactant molar ratio and reaction conditions to obtain the intermediate II containing 12 terminal hydroxyl groups (otherwise, 12 hydroxyl groups cannot be obtained, and only 6 or 4 terminal hydroxyl groups may be obtained). The final product is to carry out a final esterification reaction of acrylic acid and intermediate II, and it is necessary to strictly control the reaction acid value to reach a certain value, and the excess carboxyl groups are reacted with epoxy groups to complete the final reaction product with good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the synthesis route diagram of the present invention. DETAILED DESCRIPTION

[0020] Example 1

[0021] A method for preparing a photosensitive dodecafunctional polyester acrylate comprises the following steps:

[0022] (1) 8.8 parts by mass of terephthaloyl chloride was dissolved in 6.5 parts by mass of toluene and slowly added dropwise to 6.5 parts by mass of toluene in which 16.5 parts by mass of citric acid was dissolved. A slight vacuum of -0.009 MPa was used to remove the acid mist generated by the reaction. The dropping time was 6 hours. After the dropping was completed, the reaction was continued under vacuum. The reaction temperature was controlled at -5°C. The reaction time was 11 hours. After the reaction was completed, an intermediate I was obtained. The reaction yield was about 96%. The intermediate I 1H-NMR test showed that the peak at position 2.0, which represented the displacement of the alcoholic hydroxyl group in citric acid, disappeared completely, while the peak at position 8.1, which represented the displacement of hydrogen on the benzene ring, and the peak at position 11.0, which represented the displacement of hydrogen on the carboxyl group in citric acid, appeared simultaneously, indicating that intermediate I was successfully synthesized.

[0023]

[0024] (2) The intermediate I was mixed evenly with 23.5 parts by weight of glycerol, and then 0.1 parts by weight of hypophosphorous acid as an antioxidant and 0.3 parts by weight of p-toluenesulfonic acid as a catalyst were added. The reaction time was controlled to be 8 hours and the reaction temperature was 125°C. When the acid value was lower than 3 mgKOH / g, the temperature was lowered to terminate the reaction to obtain the intermediate II. The reaction yield was about 95%, and the intermediate II 1 The H-NMR test showed that the peak area ratio of 2.0 displacement of hydrogen on the hydroxyl group and 8.1 displacement of hydrogen on the benzene ring was about 3:1, which was consistent with the theoretical data of the designed structure, and intermediate II was successfully synthesized.

[0025]

[0026] (3) The intermediate II was mixed evenly with 36.5 parts by weight of acrylic acid, and then 0.2 parts by weight of hypophosphorous acid as an antioxidant, 0.1 parts by weight of hydroquinone as an inhibitor, and 0.7 parts by weight of p-toluenesulfonic acid as a catalyst were added. The reaction time was controlled to be 9 hours and the reaction temperature was 120°C. When the acid value was lower than 10 mgKOH / g, the temperature was lowered to below 80°C, and 1 part by weight of trimethylolethane polyglycidyl ether and 0.1 parts by weight of benzyltriethylammonium chloride as a catalyst were added. The reaction time was controlled to be 1.5 hours and the reaction temperature was 110°C. After the reaction was completed, a vacuum of -0.1 MPa was opened and the solvent was removed for 2.5 hours to obtain the final product, a photosensitive twelve-official polyester acrylate, with a reaction yield of about 95%.

[0027]

[0028] Example 2

[0029] A method for preparing a photosensitive dodecafunctional polyester acrylate comprises the following steps:

[0030] (1) 7 parts by mass of terephthaloyl chloride was dissolved in 6.5 parts by mass of toluene and the mixture was slowly added dropwise to 6.5 parts by mass of toluene in which 16.5 parts by mass of citric acid was dissolved. A slight vacuum of -0.006 MPa was used to remove the acid mist generated by the reaction. The addition time was 5 hours. After the addition was completed, the reaction was continued under vacuum. The reaction temperature was controlled at 10° C. The reaction time was 8 hours. After the reaction was completed, an intermediate I was obtained with a reaction yield of 82%. 1The H-NMR results showed that the peak area ratio of 11.0 shifts representing hydrogen on the carboxyl group in citric acid and 8.1 shifts representing hydrogen on the benzene ring was less than 3:2, indicating that the synthesis of intermediate I was not fully achieved under the above reaction conditions.

[0031] (2) The intermediate I reaction product of step (1) was mixed evenly with 24.5 parts by mass of glycerol, and then 0.2 parts by mass of hypophosphorous acid as an antioxidant and 0.3 parts by mass of p-toluenesulfonic acid as a catalyst were added, and the reaction time was controlled to be 8 hours, and the reaction temperature was 150° C. When the acid value was lower than 3 mgKOH / g, the reaction was terminated by cooling to obtain intermediate II. The reaction yield was 66%. Since intermediate I did not achieve the ideal synthesis effect, the expected goal could not be achieved when synthesizing intermediate II, and the yield was significantly reduced.

[0032] (3) The intermediate II reaction product of step (2) was mixed evenly with 35.5 parts by weight of acrylic acid, and then 0.2 parts by weight of hypophosphorous acid as an antioxidant, 0.1 parts by weight of hydroquinone as an inhibitor, and 0.7 parts by weight of p-toluenesulfonic acid as a catalyst were added, and the reaction time was controlled to be 7 hours, and the reaction temperature was 120°C. When the acid value was lower than 10 mgKOH / g, the temperature was lowered to below 80°C, and 1.5 parts by weight of trimethylolethane polyglycidyl ether and 0.3 parts by weight of benzyltriethylammonium chloride as a catalyst were added, and the reaction time was controlled to be 1 hour, and the reaction temperature was 115°C. After the reaction was completed, a vacuum of -0.1 MPa was opened, and the solvent was removed for 2 hours to obtain the final product, a photosensitive twelve-official polyester acrylate. The reaction yield was only 64%, and the reaction conditions were not ideal.

[0033] Example 3

[0034] A method for preparing a photosensitive dodecafunctional polyester acrylate comprises the following steps:

[0035] (1) 8.8 parts by mass of terephthaloyl chloride was dissolved in 6.5 parts by mass of toluene and slowly added dropwise to 6.5 parts by mass of toluene in which 16.5 parts by mass of citric acid was dissolved. A slight vacuum of -0.006 MPa was used to remove the acid mist generated by the reaction. The dropping time was 6 hours. After the dropping was completed, the reaction was continued under vacuum. The reaction temperature was controlled at -5°C. The reaction time was 11 hours. After the reaction was completed, an intermediate I was obtained. The reaction yield was about 87%. The intermediate I 1 H-NMR test shows that the peak at position 2.0, which represents the displacement of the hydroxyl group in citric acid, has not completely disappeared, which indicates that the intermediate I containing six terminal carboxyl groups has not been completely synthesized, compared with Example 1. This indicates that the control of the vacuum degree in this step is very important.

[0036] (2) The intermediate I reaction product of step (1) was mixed evenly with 23.5 parts by mass of glycerol, and then 0.1 parts by mass of hypophosphorous acid as an antioxidant and 0.3 parts by mass of p-toluenesulfonic acid as a catalyst were added, and the reaction time was controlled to be 6 hours, and the reaction temperature was 120° C. When the acid value was lower than 3 mgKOH / g, the temperature was lowered to terminate the reaction, and the intermediate II was obtained. The reaction yield was about 83%, and the product yield was significantly reduced because the structure of the intermediate I was not fully formed.

[0037] (3) The intermediate II reaction product obtained in step (2) was uniformly mixed with 36.5 parts by weight of acrylic acid, and then 0.2 parts by weight of hypophosphorous acid as an antioxidant, 0.1 parts by weight of hydroquinone as an inhibitor, and 0.7 parts by weight of p-toluenesulfonic acid as a catalyst were added. The reaction time was controlled to be 6 hours and the reaction temperature was 125° C. When the acid value was lower than 10 mgKOH / g, the temperature was lowered to below 80° C., 1 part by weight of trimethylolethane polyglycidyl ether and 0.1 parts by weight of benzyltriethylammonium chloride as a catalyst were added, and the reaction time was controlled to be 1 hour and the reaction temperature was 115° C. After the reaction was completed, a vacuum of -0.1 MPa was opened and the solvent was removed for 2.5 hours to obtain the final finished product, a photosensitive twelve-official polyester acrylate, with a yield of 82%.

[0038] Example 4 Performance Test

[0039] The performance of the final product of the reaction of Example 1 above was measured, and the specific experimental results are shown in Table 1 below.

[0040] Table 1 Performance test results

[0041]

[0042] Note: The curing speed in the table is directly on a UV curing machine at 80mW / cm 2 The light intensity curing test was obtained.

[0043] Since the reaction conditions such as different reaction temperatures, reaction times and vacuum degrees will lead to obvious differences in the degree of reaction, selecting a more suitable reaction condition is the main research direction of this invention. The above experimental results show that the reaction conditions in Example 1 prepared by the present invention are the most suitable, and the obtained dodecafunctional acrylate has outstanding advantages such as low viscosity, curing speed, high paint film hardness and excellent storage stability.

[0044] 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 method for preparing a photosensitive dodecafunctional polyester acrylate, characterized in that: The following steps are involved: (1) First, terephthaloyl chloride and citric acid are reacted under certain reaction conditions to obtain an intermediate I having six terminal carboxyl groups; (2) then reacting the intermediate I with propylene glycol under certain conditions to obtain an intermediate II having twelve hydroxyl groups at the end; (3) Finally, the intermediate II is further reacted with acrylic acid and trimethylolethane polyglycidyl ether under certain reaction conditions to obtain a photosensitive dodecafunctional polyester acrylate.

2. The method for preparing a photosensitive dodecafunctional polyester acrylate according to claim 1, characterized in that: The following steps are involved: (1) firstly selecting 5-15 parts by weight of terephthaloyl chloride and 10-30 parts by weight of citric acid to prepare an intermediate I having six terminal carboxyl groups through certain reaction conditions; (2) then reacting the intermediate I with 10-30 parts by weight of propylene glycol under certain conditions to obtain an intermediate II having twelve hydroxyl groups at the end; (3) Finally, the intermediate II is further reacted with 25-50 parts by weight of acrylic acid and 0.5-3 parts by weight of trimethylolethane polyglycidyl ether under certain reaction conditions to obtain a photosensitive dodecafunctional polyester acrylate.

3. The method for preparing the photosensitive dodecafunctional polyester acrylate according to claim 2, characterized in that: The specific steps of step (1) are as follows: dissolving terephthaloyl chloride in 6.5 parts by weight of toluene, slowly dropping the mixture into 6.5 parts by weight of toluene in which citric acid is dissolved, while using a slight vacuum of -0.005 to -0.01 MPa to remove the acid mist generated by the reaction, the dropping time is 1 to 8 hours, and after the dropping is completed, the reaction is continued under vacuum, the reaction temperature is controlled between -10°C and 30°C, the reaction time is 5 to 12 hours, and after the reaction is completed, the temperature is lowered to obtain an intermediate I with six terminal carboxyl groups; 4. The method for preparing the photosensitive dodecafunctional polyester acrylate according to claim 2, characterized in that: The specific steps of step (2) are: adding glycerol to intermediate I, then adding 0-0.5 parts by weight of an antioxidant hypophosphorous acid and 0-0.5 parts by weight of a catalyst p-toluenesulfonic acid, controlling the reaction time to be 5 to 10 hours, the reaction temperature to be 110° C. to 160° C., and when the acid value is lower than 3 mgKOH / g, cooling and terminating the reaction to obtain intermediate II; 5. The method for preparing the photosensitive dodecafunctional polyester acrylate according to claim 2, characterized in that: The specific steps of step (3) are: adding acrylic acid to intermediate II, and then adding 0-0.5 parts by weight of an antioxidant hypophosphorous acid, 0-0.5 parts by weight of a polymerization inhibitor hydroquinone and 0-1 parts by weight of a catalyst p-toluenesulfonic acid, controlling the reaction time to be 5 to 10 hours, and the reaction temperature to be 90° C. to 130° C., when the acid value is lower than 10 mgKOH / g, cooling to below 80° C., adding trimethylolethane polyglycidyl ether and 0-0.5 parts by weight of a catalyst benzyltriethylammonium chloride, controlling the reaction time to be 1 to 3 hours, and the reaction temperature to be 90-130° C., and after the reaction is completed, opening a vacuum of -0.1 MPa, and desolventizing for 1 to 3 hours to obtain a final finished product, a photosensitive twelve-official polyester acrylate; 6. Use of the photosensitive dodecafunctional polyester acrylate prepared by the method of any one of claims 1 to 5 in preparing oligomers for photosensitive coatings.

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