TW201932444A - Method for enhancing reaction efficiency of terephthalate plasticizer capable of reducing reaction time in a process for producing terephthalate plasticizer - Google Patents

Abstract

Provided is a method for enhancing reaction efficiency of terephthalate plasticizer, which includes using a homogenizer to fine PTA to generate slurry having a particle size of 80-110 <mu>m, and esterifying the PTA slurry with a C6-C10 alcohol in the presence of a titanium-based catalyst. Accordingly, the reactivity is enhanced by more than 50%, and the synthetized terephthalate plasticizer is low-odor and has a purity of more than 99.5% as well as satisfactory physical properties such as acid value, color, and index of refraction.

Description

Method for improving reaction efficiency of terephthalate plasticizer

The present invention relates to a terephthalate plasticizer, which is a linear or branched alcohol of terephthalic acid (hereinafter referred to as PTA) and 6 carbons to 10 carbons (C6 to C10) (hereinafter referred to as C6-C10 alcohol). ) obtained by esterification synthesis reaction.

Currently used terephthalic acid plasticizer, diisobutyl phthalate (DOTP; Di(2-ethylhexyl) terephthalate), is an environmentally friendly plasticizer, DOTP plasticizer from PTA (terephthalic acid) ) It is obtained by esterification synthesis with 2EH (2-ethylhexanol). PTA is insoluble in 2EH and general solvent. Therefore, it is a heterogeneous solid-liquid phase reaction during esterification synthesis. PTA is easy to precipitate and agglomerate during the reaction. It is also limited by the solubility of PTA in 2EH. The reaction only occurs between the interface of PTA and 2EH, resulting in a very slow reaction rate and a long reaction time. At present, industrial production of DOTP mostly uses titanate as a catalyst, and the reaction time is at least 5 hours. Therefore, the problem that PTA is not compatible with 2EH and the reaction time is long has not been solved.

Regarding the method for improving the reactivity of dioctyl terephthalate, the CN102329233 patent uses a quaternary ammonium salt ionic liquid as a cocatalyst and a solubilizing agent, but the ionic liquid may cause a side reaction or a catalyst during the esterification reaction, and finally Separation must be carried out during the purification stage, with an increase Disadvantages such as process and production time. U.S. Patent No. 2,020, 289, 963 A1 discloses an esterification process by azeotropic distillation with an alcohol followed by water removal. Although the esterification reaction time is reduced, it is reduced by 9-11%, and the amplitude is still small.

In view of the above, the object of the present invention is to improve the reactivity of terephthalate esters, and the PTA can be agglomerated by a homogenizer to avoid agglomeration and agglomeration of the PTA, and the reaction liquid is not easy to foam and avoid adhesion to the groove wall, especially homogenization. Machine-treated PTA, the surface of which forms wrinkles, is beneficial to increase the surface area and 2EH penetration into the PTA inner layer reaction, thereby improving the reactivity and shortening the reaction time to the general esterification process conditions: pressure under negative pressure 30 mbar to normal pressure (-30~1013mbar), 180~250°C, the effect of shortening the reaction time by 50% can be achieved. The purity of the synthesized terephthalate plasticizer can reach above 99.5%, and the physical properties such as acid value, hue and refractive index. All of them are qualified, which has the advantages of increasing production and energy saving. The terephthalate plasticizer produced has low odor characteristics.

After mixing the synthetic raw materials terephthalic acid (PTA) and C6~C10 alcohol, the PTA is subdivided by a homogenizer, wherein the homogenizer subdivids the mixture to a particle size of 80-110 um and increases the surface area by 5-10%, subdivided. The purified slurry is pumped to the reaction tank for direct esterification reaction with excess alcohol; the method comprises: (1) PTA and C6~C10 alcohol are mixed according to the weight ratio of 1:0.8~1.5, and then treated by homogenizer PTA slurry is formed after 2~8 hours; (2) based on the total amount of terephthalate plasticizer finished product, 85~107wt% of the total amount of finished product is 30~85wt% C6~C10 Alcohol is used as raw material; (3) Based on the total amount of the terephthalate plasticizer, 0.1 to 2.0 wt% of the titanium metal catalyst is used as the esterification catalyst; (4) at a reaction temperature of -30 to 1013 mbar, the reaction temperature is 200 to 250 ° C, The esterification reaction is carried out for 2 to 3 hours; (5) after completion of the reaction, the reaction mixture is neutralized with an aqueous alkali metal hydroxide solution containing 5 to 20% by weight of the hydroxide mixture until the acid value of the reaction mixture reaches 0.07 mgKOH/g or less. At the same time, the excess alcohol is removed, dried and filtered to prepare a finished terephthalate plasticizer.

Figure 1 is a surface SEM image of PTA not subdivided.

Figure 2 is a surface SEM image of PTA subdivision six times.

The method for preparing a terephthalate plasticizer according to the present invention uses a mixture of terephthalic acid and a C6-C10 alcohol as a raw material, and firstly mixes terephthalic acid and C6-C10 alcohol according to a weight ratio of 1:0.8-1.5. Then, after subdividing by a homogenizer, the esterification reaction is carried out in the presence of a titanium metal catalyst, and after the reaction is completed, the neutralization reaction is carried out with an aqueous solution of an alkali metal hydroxide, and then the excess reaction alcohol is removed, and finally dried. Filtration and purification to obtain a terephthalate plasticizer ester with high purity and good color. The specific method includes the following steps: 1) preparing PTA slurry: taking PTA and C6~C10 alcohol according to weight ratio 1:0.8 After ~1.5 phase mixing, then again After 2~8 hours of processing, the PTA slurry (ie: PTA+C6~C10 alcohol) is formed; the particle size can be subdivided to 80~110um and the surface area is increased by 5~10%, especially the particle size: 100~110um, surface area Increasing 7~10% is the best, but the particle size is smaller, but there is a problem of agglutination; 1) Based on the total amount of the terephthalate plasticizer, the total amount of the finished product is 85~107wt% of the terephthalic acid slurry. 30~85wt% C6~C10 alcohol as raw material; 2) 0.1~2.0wt% metal catalyst as esterification catalyst based on total amount of terephthalate plasticizer; 4) reaction pressure-30 ~1013 mbar and a reaction temperature of 200-250 ° C, a mixture of terephthalic acid or its derivative of step 1) and a C6-C10 alcohol mixture, in the presence of the metal catalyst, esterification reaction for 2 to 3 hours, Until the acid value of the reaction mixture reaches 0.1 mgKOH/g or less; 5) after completion of the reaction, the reaction mixture is neutralized with an aqueous alkali metal hydroxide solution containing 5 to 20% by weight of the hydroxide mixture until the acid value of the reaction mixture reaches 0.07 mgKOH. When it is less than /g, the excess alcohol is removed, dried, and filtered to prepare a terephthalate plasticizer.

The esterification catalyst is a metal-containing catalyst: tetraisopropyl titanate (TIPT), tetraisobutyl titanate (TIBT), tetrahydro-2-ethylhexyl titanate (Tetra 2-Ethylhexyl Titanate, EHT) One or more of them.

The reaction water formed therein is an azeotropic mixture with the alcohol used under vacuum pressure or normal pressure, and is removed from the reaction mixture.

After the esterification reaction is completed, the catalyst is removed by water vapor and activated carbon.

Wherein the aqueous alkali metal hydroxide solution is used in excess, corresponding to the acid of the reaction mixture The price is 4~5 times.

The DOTP plasticizer produced by this method has more than doubled the reaction efficiency, reduced the reaction time by half, and the plasticizer finished product can reach a low odor level. The composition of the above PTA and C6~C10 alcohol may also be mixed according to the weight ratio of 1:0.8~1.5, and then treated by a homogenizer for about 2-8 hours, the particle size is below 80~110um, and then the reaction pressure is -30. The esterification reaction is carried out for 2 to 3 hours at ~1013 bar and at a reaction temperature of 200 to 250 ° C, which greatly shortens the reaction time.

[Simple description of the map]

Figure 1 is a surface SEM image of PTA that is not subdivided.

Figure 2 is a surface SEM image of PTA subdivided six times.

The raw materials for the esterification reaction of the present invention are terephthalic acid and C6 to C10 alcohol. Among them, the alcohol composition includes 2-ethylhexanol (2-EH), isodecyl alcohol, isodecyl alcohol and the like.

The plasticizers prepared by the esterification reaction of the following examples and comparative examples were tested for physical properties according to the following evaluation methods:

The odor level analysis was analyzed by the odor analyzer AlphaMOS E-NOSE Heracles II. The particle size of the PTA was analyzed by a laser particle size analyzer (LS13320). The specific surface area of the PTA sample was analyzed by a high resolution specific surface area and a microporous analyzer BET (ASAP 2020 micromeritics Surface Area and Porosity Analyzer), and the sample weight was 0.1 to 0.3 g.

[Examples and Comparative Examples] [Example 1]

As shown in Table 1, the PTA composition was first subdivided by a homogenizer. (1) 119 g of terephthalic acid (PTA) was mixed with 119 g of the slurry solvent 2-EH to obtain a homogenizer (the specification: 3000). ~6000rpm, horsepower: 50~60Hz) slurry after 6 treatments, (2) add alcohol 2-EH to take 161g slurry of PTA residue after cleaning homogenizer, catalyst TIPT (tetraisopropyl titanium) The amount of the acid ester added is 0.6g, and the slurry of (1) and (2) is mixed and the catalyst is simultaneously fed into the four-necked flask. The reaction temperature is gradually increased from 180 ° C to 225 ° C under nitrogen, and the reaction time is 2.5. After the reaction pressure is 1013 mbar for 1.5 hours, and then reacted at -30 mbar for 1 hour, the water must be removed during the reaction, and when the reaction is carried out until the acid value is 1 mgKOH/g or less, neutralization to synthesis is carried out with an aqueous solution of an alkali metal hydroxide. When the acid value of the reaction mixture is 0.07 mgKOH/g or less, distillation is carried out to reduce the alcohol content to 300 ppm or less, followed by filtration purification.

[Example 2]

As shown in Table 1, the PTA is subdivided first. (1) 119 g of terephthalic acid (PTA) is mixed with 119 g of the slurry solvent 2-EH, and then treated with a homogenizer for 9 times. 2) Adding alcohol 2-EH and taking 161g of the slurry after cleaning the PTA residue of the homogenizer, the catalyst TIPT (tetraisopropyl titanate) is added in an amount of 0.6g, and then (1) and (2) pulp After mixing, the catalyst was simultaneously fed into a four-necked flask. The reaction temperature was gradually increased from 180 ° C to 225 ° C under nitrogen, the reaction time was 2.5 hours, the reaction pressure was 1013 mbar for 1.5 hours, and then the reaction was carried out at -30 mbar for 1 hour. The water must be removed during the reaction, and the reaction is carried out until the acid value is 1 mgKOH/g or less, and the solution is neutralized with an aqueous solution of an alkali metal hydroxide. When the acid value of the synthesis reaction mixture is 0.07 mgKOH/g or less, distillation is carried out to reduce the alcohol content to 300 ppm or less, followed by filtration purification.

[Example 3]

As shown in Table 1, the composition of Example 1 was the same as that of Example 1, except that the PTA/2EH slurry composition ratio was 1:1.3, and the results are shown in Table 1.

[Embodiment 4]

As shown in Table 1, the composition was the same as that of Example 1, except that the PTA/2EH slurry composition ratio was 1:1.5, and the results are shown in Table 1.

[Embodiment 5]

As in the formulation of Table 1, the same procedure as in Example 1 was carried out except that the synthetic raw material alcohol replaced 2-EH with INA, and the slurry solvent replaced 2-EH with INA. The results are shown in Table 1.

[Embodiment 6]

As shown in Table 1, the same procedure as in Example 2 was carried out except that the synthetic raw material alcohol was substituted with 2-EH for INA, and the slurry solvent was substituted for 2-EH with INA. The results are shown in Table 1.

[Embodiment 7]

As shown in Table 1, the composition of the same method as in Example 1, except that the catalyst was changed to 1.0 g, and the results are shown in Table 1.

[Embodiment 8]

As shown in Table 1, the same method as in Example 1, except PTA/2EH slurry composition ratio An example is 1:0.8, and the results are shown in Table 1.

[Embodiment 9]

The formulation of Table 1 was the same as that of Example 1, except that the PTA/2EH slurry composition ratio was 1:0.9, and the results are shown in Table 1.

As shown in Table 1, the PTA (particle size: 141.2um) is not subdivided by a homogenizer. (1) phthalic acid (PTA) 119g, then 2-EH 280g, catalyst TIPT (tetraisopropyl) The titanate was added in an amount of 0.6 g, and was fed into a four-necked flask. The reaction temperature was gradually increased from 180 ° C to 225 ° C under nitrogen, the reaction was carried out at a pressure of 1013 mbar for 4.5 hours, and then reacted at -30 mbar for 1 hour. The water must be removed, and when the reaction is carried out until the acid value is 1 mgKOH/g or less, when the acid is neutralized with an aqueous solution of an alkali metal hydroxide to a pH of 0.07 mgKOH/g or less of the synthesis reaction mixture, distillation is carried out to reduce the alcohol content to 300 ppm. Following the filtration, purification was further carried out.

[Comparative Example 2]

As shown in Table 1, the composition was the same as that of Comparative Example 1, except that PTA replaced 141.2 um with a particle size of 100.3 um.

[Comparative Example 3]

As shown in Table 1, the formulation was the same as that of Comparative Example 1, except that PTA replaced 141.2 um with a particle size of 120.4 um.

Discussion of the results:

1. Using a homogenizer (segment 3 rotor 3 stator; subdivided PTA, as shown in Table 1 with 2-EH/PTA or INA/PTA in a ratio of 1:0.8~1.5, respectively, subdivided into 6, 9 Then, according to the formula of Table 1, the direct esterification reaction is carried out after the amount of 2-EH or INA is supplemented. The synthesis time and heat history are shortened, the odor is reduced and the productivity is improved.

2. After the 6-time homogenizer treatment of the PTA slurry of Example 1, the PTA particle size was reduced from 141.2 to 107.3 μm, and the specific surface area was increased by 9.3%. After the PTA slurry of Example 2 was treated by a 9-time homogenizer, the PTA particle size was reduced from the original 141.2 to 103.2 μm, and the specific surface area was increased by 9.9%. After the 6-time homogenizer treatment of the PTA slurry of Example 3, the PTA particle size was reduced from 141.2 to 108.6 μm, and the specific surface area was increased by 8.87%. After the PTA slurry of Example 4 was treated by a 9-time homogenizer, the PTA particle size was reduced from 141.2 to 103.2 μm, and the specific surface area was increased by 9.79%. After the 6-time homogenizer treatment of the PTA slurry of Example 5, the PTA particle size was reduced from the original 141.2 to 101 μm, and the specific surface area was increased by 5.21%. After the PTA slurry of Example 6 was treated by 9 homogenizers, the PTA particle size was reduced from 141.2 to 82 μm, and the specific surface area was increased by 7.23%. After the PTA slurry of Example 7 was treated by 6 homogenizers, the PTA particle size was determined by The original 141.2 was reduced to 106.5 μm, and the specific surface area was increased by 9.47%. After the 6-time homogenizer treatment of the PTA slurry of Example 8, the PTA particle size was reduced from the original 141.2 to 106.2 μm, and the specific surface area was increased by 9.3%. The PTA of Example 9 After the slurry is treated by 6 homogenizers, the PTA particle size is determined by The original 141.2 was reduced to 107.2 μm, and the specific surface area was increased by 9.4%. In the above Examples 1 to 9, the PTA was subdivided by a homogenizer, and then esterification reaction was carried out according to the formulation of Table 1, and the esterification time was reduced from 5 hours to 2.5 hours. The odor is reduced from 4.5 to 3.

3. The DOTP plasticizer produced in the examples has more than doubled the reaction efficiency, reduced the reaction time by half, and the plasticizer finished product can reach a low odor level.

4. The particle size of Example 6 is less than 82 um, and there is agglomeration, and the surface area increase rate is only 5.21%, so it is not suitable for further refinement.

Note: 1. The composition weight ratio of the slurry is the ratio of PTA: slurry solvent. 2. The total amount of alcohol in the formula = slurry solvent + external addition of alcohol. For example, the total amount of alcohol in the formulation of Example 1 (280 g) = slurry solvent (2EH: 119 g) + external addition (2-EH: 161 g). The total amount of alcohol in the formulation of Example 3 (280 g) = slurry solvent (2EH: 154.7 g) + external addition (2-EH: 125.3 g). The total amount of alcohol in the formulation of Example 5 (310 g) = slurry solvent (INA: 119 g) + external addition (INA: 191 g). The total amount of alcohol in the formulation of Example 8 (280 g) = slurry solvent (2EH: 119 g) + external addition (2EH: 184.8 g). 3. Surface area increase rate (%) calculation: specific surface area of PTA after homogenization of the homogenizer / PTA undivided specific surface area (ie, specific surface area of Comparative Example 1) × 100%. For example, the surface area increase rate (%) of Example 1 = (0.3795 - 0.3472) / 0.3472 = 9.3%. The surface area increase rate (%) of Example 2 = (0.3816 - 0.3472) / 0.3472 = 9.9%. The calculation of the surface area increase rate (%) of the other Examples 3 to 9 and Comparative Examples 1 to 3 and the like. 4. Odour analysis grade: The smaller the grade value, the better the smell.

Claims (7)

A method for improving the reaction efficiency of a terephthalate plasticizer, characterized in that after the synthetic raw material terephthalic acid (PTA) and the alcohol phase are mixed, the PTA is subdivided by a homogenizer, wherein the homogenizer subdivided mixture To the particle size of 80~110um and increase the surface area by 5~10%, the subdivided slurry is pumped to the reaction tank for direct esterification reaction with excess alcohol; the method comprises: (1) PTA and C6~C10 alcohol After the weight ratio is 1:0.8~1.5, the homogenizer is treated for 2~8 hours to form a terephthalic acid slurry; (2) based on the total amount of the terephthalate plasticizer finished product, the total amount of the finished product is taken. 75~107wt% of terephthalic acid slurry and 30~85wt% C6~C10 alcohol as raw materials; (3) 0.1~2.0wt% titanium metal catalyst based on the total amount of terephthalate plasticizer finished products It is an esterification catalyst; (4) the esterification reaction is carried out for 2 to 3 hours at a reaction pressure of -30 to 1013 mbar and a reaction temperature of 200 to 250 ° C; (5) after completion of the reaction, the reaction mixture contains 5 to 20 wt% of hydrogen. Neutralizing the alkali metal hydroxide aqueous solution of the oxide mixture until the acid value of the reaction mixture reaches 0.07 mgKOH/g or less, and then removing excess alcohol, drying and Filtration, preparation of the finished product of terephthalate plasticizer. The method of claim 1, wherein the catalyst is a titanium metal catalyst: tetraisopropyl titanate (TIPT), tetraisobutyl titanate (TIBT), tetraiso-2-ethyl One or more of Tetra 2-Ethylhexyl Titanate (EHT). The method of claim 1, wherein the formed reaction water is removed from the reaction mixture under vacuum pressure or under normal pressure with an azeotropic mixture with the alcohol used. The method of claim 1, wherein the catalyst is removed by water vapor or activated carbon after the esterification reaction is completed. The method of claim 1, wherein the (5) aqueous alkali metal hydroxide solution is used in excess, corresponding to 4 to 5 times the acid value of the reaction mixture. For example, the method described in claim 1 wherein the homogenizer subdivided the mixture to a particle size of 100 to 110 um and a surface area of 5 to 10% is optimal. A DOTP plasticizer prepared by the method of claim 1 of the patent application.