TWI691481B - Method for improving reaction efficiency of terephthalate plasticizer - Google Patents

Abstract

A method for improving the reaction efficiency of terephthalate plasticizer, using a homogenizer to subdivide PTA to a particle size of 80~110 μm and a C6~C10 alcohol mixture, and carry out an esterification reaction in the presence of a titanium metal catalyst. The reactivity can be increased by more than 50%, and the purity of the synthesized terephthalate plasticizer can reach more than 99.5%. The acid value, hue, refractive index and other physical properties are all qualified and the low odor terephthalate plasticizer .

Description

Method for improving reaction efficiency of terephthalate plasticizer

The present invention relates to terephthalate plasticizers, from terephthalic acid (hereinafter referred to as PTA) and 6 to 10 carbon (C6~C10) linear or branched alcohol (hereinafter referred to as C6~C10 alcohol) ) The esterification synthesis reaction.

The terephthalic acid plasticizer commonly used at present, diisooctyl terephthalate (DOTP; Di(2-ethylhexyl) terephthalate), is an environmentally friendly plasticizer. The DOTP plasticizer is made of PTA (terephthalic acid ) And 2EH (2-ethylhexanol) esterification synthesis reaction, PTA is not soluble in 2EH and general solvents, so esterification synthesis is a heterogeneous solid-liquid reaction, PTA is easy to precipitate and agglomerate during the reaction process, 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 long reaction time. At present, industrial production of DOTP mostly uses titanate as the catalyst, and the reaction time is at least 5 hours, so the problems of PTA and 2EH incompatibility and long synthesis reaction time have not been solved.

Regarding the method for improving the reactivity of dioctyl terephthalate, the CN102329233 patent uses quaternary ammonium salt ionic liquid as a cocatalyst and solubilizer, but the ionic liquid may produce side reactions or interact with the catalyst during the esterification reaction, and finally In the purification section, static separation is required. Shortcomings such as process and production time. US Patent 2002028963A1 discloses an esterification method by azeotropic distillation with alcohol to remove water. Although the esterification reaction time is reduced, the reduction is 9 to 11%, and the range is still not large.

In view of this, the purpose of the present invention is to improve the reactivity of terephthalic acid esters. The use of a homogenizer to subdivide PTA can avoid PTA agglomeration and agglomeration, and the reaction liquid is not easy to foam to avoid adhesion to the tank wall, especially after homogenization. The surface of the mechanically processed PTA is formed with wrinkles, which is beneficial to increase the surface area and 2EH infiltrate into the inner layer of the PTA to improve the reactivity and shorten the reaction time. The general esterification process conditions: the pressure is below 30 mbar to normal pressure (-30~1013mbar), 180~250℃, the effect of shortening the reaction time by 50% can be achieved, the purity of the synthesized terephthalate plasticizer can reach more than 99.5%, and the physical properties such as acid value, hue, refractive index, etc. They are all qualified and have the advantages of increasing output and saving energy. The produced terephthalate plasticizer has low odor characteristics.

After mixing with synthetic raw materials terephthalic acid (PTA) and C6~C10 alcohols, the PTA is subdivided by a homogenizer, where the homogenizer subdivides the mixture to a particle size of 80~110 μ m and increases the surface area by 5~10% , The subdivided slurry is pumped to the reaction tank and produced by direct esterification reaction with excess alcohol; the method includes: (1) PTA and C6~C10 alcohol are mixed according to the weight ratio of 1:0.8~1.5, and then homogenized After processing for 2~8 hours, PTA slurry is formed; (2) Based on the total amount of finished terephthalate plasticizer, 85~107wt% terephthalic acid paste and 30~85wt% C6 are taken from the total finished product ~C10 alcohol as raw material; (3) Based on the total amount of terephthalate plasticizer, 0.1~2.0wt% titanium metal catalyst is used as esterification catalyst; (4) Reaction temperature at reaction pressure -30~1013mbar The esterification reaction is carried out at 200~250℃ for 2~3 hours; (5) After the reaction is completed, the reaction mixture is neutralized with an aqueous solution of alkali metal hydroxide containing 5~20wt% hydroxide mixture until the acid value of the reaction mixture When it is less than 0.07mgKOH/g, excess alcohol is removed, dried and filtered to prepare a finished product of terephthalate plasticizer.

Figure 1 is a SEM image of the PTA unsubdivided surface.

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

The method for manufacturing terephthalate plasticizer of the present invention uses terephthalic acid and a C6~C10 alcohol-containing mixture as raw materials, and first mixes terephthalic acid and C6~C10 alcohol in a weight ratio of 1:0.8~1.5 After further subdivision with a homogenizer, the esterification reaction is carried out in the presence of a titanium metal catalyst. After the reaction is completed, the neutralization reaction is carried out with an aqueous solution of alkali metal hydroxide, then excess reaction alcohol is removed, and finally drying 1. Filtration and purification to obtain high purity and good hue esters of terephthalate plasticizer. The specific preparation method includes the following steps: 1) First prepare PTA slurry: take PTA and C6~C10 alcohol in weight ratio of 1:0.8 After mixing ~1.5 phases, then process it with a homogenizer for 2-8 hours to form a PTA slurry (ie: PTA+C6~C10 alcohol); the particle size can be subdivided to 80~110 μ m and the surface area increased by 5~10%, In particular, the particle size: 100~110 μ m, the surface area increased by 7~10% is the best, but the particle size is small, but it has poor aggregation; 1) based on the total amount of terephthalate plasticizer, take the finished product The total amount of 85~107wt% terephthalic acid slurry and 30~85wt% C6~C10 alcohol as raw materials; 2) Based on the total amount of terephthalate plasticizer, take 0.1~2.0wt% metal catalyst as Esterification catalyst; 4) At a reaction pressure of -30~1013 mbar and a reaction temperature of 200~250°C, for the mixture of terephthalic acid or its derivative and C6~C10 alcohol in step 1), the metal catalyst In the presence of, the esterification reaction is carried out for 2~3 hours until the acid value of the reaction mixture reaches below 0.1mgKOH/g; 5) After the reaction is completed, the reaction mixture is an aqueous solution of alkali metal hydroxide containing 5~20wt% hydroxide mixture Neutralize until the acid value of the reaction mixture reaches below 0.07mgKOH/g, then remove excess alcohol, dry and filter to prepare a terephthalate plasticizer.

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

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 with steam and activated carbon.

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

The DOTP plasticizer produced by this method has more than doubled its reaction performance, shortened the reaction time by half, and its finished plasticizer can reach a low odor level. The composition of the above PTA and C6~C10 alcohols can also be mixed according to the weight ratio of 1: 0.8~1.5, and then treated with a homogenizer for about 2~8 hours, and the particle size is below 80~110 μm , and then the reaction pressure -30~1013bar and reaction temperature 200~250 ℃ for 2~3 hours, greatly shorten the reaction time.

[Simple illustration]

Figure 1 is a SEM image of PTA as an unsubdivided surface.

Figure 2 is a SEM image of the surface of PTA for six subdivisions.

The raw materials for the esterification reaction of the present invention are terephthalic acid and C6~C10 alcohol. Among them, the alcohol composition includes 2-ethylhexanol (2-EH), isononanol, isodecanol and the like. The plasticizer products prepared by the esterification reaction in the following examples and comparative examples were tested for various physical properties in accordance with the following evaluation methods: Odour grade analysis was performed according to the odor analyzer AlphaMOS E-NOSE Heracles II. The particle size of PTA is analyzed by laser particle size analyzer (LS13320). The specific surface area of the PTA sample is analyzed by high resolution specific surface area and micropore analyzer BET (ASAP 2020 micromeritics Surface Area and Porosity Analyzer), and the sample weighs 0.1~0.3g.

[Examples and Comparative Examples]

[Example 1]

As shown in the formula in Table 1, the PTA composition is first subdivided by a homogenizer. (1 ) Take 119g of terephthalic acid (PTA), mix with 119g of slurry solvent 2-EH and use a homogenizer (the specifications: 3000 ~6000rpm, horsepower: 50~60Hz) The slurry after 6 treatments, (2) After adding alcohol 2-EH to take 161g of the slurry after cleaning the PTA residue of the homogenizer, the catalyst TIPT (tetraisopropyl titanium) Acid ester) 0.6g, then mix the slurry of (1) and (2) and feed the catalyst into the four-necked flask at the same time, the reaction temperature is gradually increased from 180℃ to 225℃ under nitrogen, the reaction time is 2.5 Hour, reaction pressure 1013 mbar 1.5 hours, then -30 mbar 1 hour, water must be removed during the reaction, when the reaction is below 1 mgKOH/g, neutralize with an aqueous solution of alkali metal hydroxide to synthesis When the acid value of the reaction mixture is less than or equal to 0.07 mgKOH/g, distillation is performed to reduce the alcohol content to less than 300 ppm, followed by filtration and purification.

[Example 2]

As shown in Table 1, the composition of PTA is first subdivided. (1) Take 119g of terephthalic acid (PTA), mix it with 119g of slurry solvent 2-EH, and then treat the slurry 9 times with a homogenizer, ( 2) Add 161g of alcohol 2-EH to the slurry after cleaning the PTA residue of the homogenizer, add 0.6g of catalyst TIPT (tetraisopropyl titanate), and then mix the (1) and (2) slurry After the body is mixed and the catalyst is fed into the four-necked flask at the same time, the reaction temperature is gradually increased from 180°C to 225°C under nitrogen, the reaction time is 2.5 hours, the reaction pressure is 1013 mbar for 1.5 hours, and then the reaction is performed at -30 mbar for 1 hour. Moisture must be removed during the reaction. When the reaction is below 1 mgKOH/g, neutralize with an aqueous solution of alkali metal hydroxide When the acid value of the synthesis reaction mixture is 0.07 mgKOH/g or less, distillation is performed to reduce the alcohol content to 300 ppm or less, and then the product is filtered and purified.

[Example 3]

The composition of the formulation as shown in Table 1 is the same as the preparation method of Example 1, except that the composition ratio of the PTA/2EH slurry is 1:1.3, and the results are shown in Table 1.

[Example 4]

The composition of the formulation as shown in Table 1 is the same as the preparation method of Example 1, except that the composition ratio of the PTA/2EH slurry is 1:1.5, and the results are shown in Table 1.

[Example 5]

The composition of the formulation in Table 1 is the same as the preparation method in Example 1, except that the synthetic raw material alcohol is replaced by INA (isononol) for 2-EH, and the slurry solvent is replaced by INA for 2-EH. The results are shown in Table 1.

[Example 6]

The composition of the formulation in Table 1 is the same as the preparation method in Example 2, except that the synthetic raw material alcohol is replaced by INA for 2-EH and the slurry solvent is replaced by INA for 2-EH. The results are shown in Table 1.

[Example 7]

As shown in Table 1, the composition of the formula is the same as the preparation method in Example 1, except that the catalyst is changed to 1.0 g. The results are shown in Table 1.

[Example 8]

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

[Example 9]

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

As shown in the formula composition in Table 1, PTA (particle size: 141.2 μm ) is not subdivided by a homogenizer. (1) Take 119g of terephthalic acid (PTA), then take 280g of 2-EH, and the catalyst TIPT (tetraisopropyl) Base titanate) in an amount of 0.6g, while feeding into a four-necked flask, the reaction temperature was gradually increased from 180°C to 225°C under nitrogen, the reaction pressure was 1013mbar after 4.5 hours of reaction, and then reacted at -30mbar for 1 hour, the reaction During the process, the water must be removed. When the reaction reaches an acid value of less than 1 mgKOH/g, it is neutralized with an aqueous solution of an alkali metal hydroxide until the acid value of the synthesis reaction mixture is less than 0.07 mgKOH/g. Distillation reduces the alcohol content to Below 300ppm, filter and purify again.

[Comparative Example 2]

The composition of the formulation as shown in Table 1 is the same as the preparation method of Comparative Example 1, except that PTA replaces 141.2 μm with a particle size of 100.3 μm .

[Comparative Example 3]

The composition of the formulation as shown in Table 1 is the same as the preparation method of Comparative Example 1, except that PTA replaces 141.2 μm with a particle size of 120.4 μm .

Results discussion:

1. Using a homogenizer (one-stage 3 rotors and 3 stators; subdivided PTA, as shown in Table 1, the slurry is mixed with 2-EH/PTA or INA/PTA at a ratio of 1:0.8~1.5, and subdivided into 6, 9 Secondly, according to the formula in Table 1, make up the amount of 2-EH or INA to carry out the direct esterification reaction. The period shortens the synthesis time and thermal history, reduces odor and increases production capacity.

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

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

4. The particle size of Example 6 is less than 82 μm , and the phenomenon of agglomeration starts, and the increase rate of the surface area is only 5.21%, so it is not appropriate to refine it.

Note:

1. The composition weight ratio of slurry is PTA: slurry solvent ratio.

2. The total amount of alcohol in the formula = slurry solvent + externally added alcohol.

For example: the total amount of alcohol in the formula 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. Calculation of surface area increase rate (%): the specific surface area of PTA after the subdivision of the homogenizer/the specific surface area of PTA without subdivision (that is, the 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 the comparative examples 1 to 3 and so on.

4. Odor analysis grade: the smaller the grade value, the better the smell.

Claims (7)

A method for improving the reaction efficiency of terephthalate plasticizers, characterized in that after the synthetic raw materials terephthalic acid (PTA) and alcohol are mixed, the homogenizer is used to process 6 to 9 times to subdivide the PTA. The homogenizer subdivides the mixture to a particle size of 80 to 110 μm and increases the surface area by 5 to 10%. The subdivided slurry is pumped to the reaction tank and produced by direct esterification reaction with excess alcohol; the method includes: (1 ) PTA and C6~C10 alcohols are mixed in a weight ratio of 1: 0.8~1.5, and then treated with a homogenizer for 6 to 9 times to form a terephthalic acid slurry; (2) finished products based on terephthalate plasticizer The total amount of the final product is 75~107wt% terephthalic acid slurry and 30~85wt% C6~C10 alcohol as raw materials; (3) Based on the total amount of finished terephthalate plasticizer, take 0.1 ~2.0wt% titanium catalyst is esterification catalyst; (4) Under the reaction pressure of -30~1013mbar and the reaction temperature of 200~250℃, the esterification reaction is carried out for 2~3 hours; (5) After the reaction is completed, the reaction The mixture is neutralized with an aqueous solution of alkali metal hydroxide containing a 5-20 wt% hydroxide mixture until the acid value of the reaction mixture reaches below 0.07 mgKOH/g, then excess alcohol is removed, dried and filtered to prepare p-benzene Finished product of diformate plasticizer. The method as described in item 1 of the patent application scope, wherein the catalyst is a titanium metal catalyst: tetraisopropyl titanate (TIPT), tetraisobutyl titanate (TIBT), tetrakis(2-ethane One or more of Tetra 2-Ethylhexyl Titanate (EHT). The method as described in item 1 of the patent application scope, wherein the formed reaction water is azeotropically mixed with the alcohol used under vacuum pressure or normal pressure, and is removed from the reaction mixture. The method as described in item 1 of the patent application scope, wherein the catalyst is removed with steam and activated carbon after the esterification reaction is completed. The method as described in item 1 of the patent application, wherein (5) the aqueous solution of alkali metal hydroxide is used in excess, which is equivalent to 4 to 5 times the acid value of the reaction mixture. The method as described in item 1 of the patent application scope, in which the homogenizer subdivides the mixture to a particle size of 100-110 μm, and the surface area is increased by 7-10%. A DOTP plasticizer, which is produced by the method described in any of items 1 to 6 of the patent application.

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