TWI788008B - Polymeric dispersant transformed through depolymerized high molecular weight polyester and method of manufacturing the same - Google Patents

Abstract

The invention discloses a polymeric dispersant and a methd of manufacturing the same. The polymeric disperant of the invention is produced through a depolymerization of a high molecular weight polyester by use of a polyol, and has a molecular weight ranging from 1,000 to 200,000 g/mol. The polymeric disperant of the invention can be used to effectively disperse inorganic particles such as titanium dioxide particles to benefit in various applications such as pigments, coatings, inks, textile dying, building materials, plastics, electronics, biomedicine and so on.

Description

High-molecular-weight dispersant converted by depolymerized high-molecular-weight polyester and method for producing the same

The present invention relates to a product transformed by depolymerized high molecular weight polyester and a method for producing the same, and in particular, to a polymeric dispersant transformed by depolymerized high molecular weight polyester dispersant) and its manufacturing method.

High molecular weight polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT) etc., have been widely used in daily life. For example, polyethylene terephthalate (PET) is widely used as textile fibers and packaging materials, such as bottles and containers for food or other consumer products. Food or other consumer products that can be contained in PET bottles or containers include soft drinks, alcoholic beverages, detergents, cosmetics, pharmaceutical products, and edible oils. Polyethylene terephthalate (PET) is also used as a film for packaging and the structure of electronic devices. As high-molecular-weight polyester products are used in large quantities, the problem of waste disposal is also becoming more and more serious. In the early years, the waste of high-molecular-weight polyester products was disposed of by landfill or incineration, but it has long been banned due to the serious impact on the environment. Therefore, recycling and reusing the waste of high molecular weight polyester products has become an important issue in energy saving and environmental protection.

Regarding the recovery and reuse of wastes of high molecular weight polyester products, many technologies and methods have been developed and proposed for PET alone. The recycling method of PET product waste is roughly divided into physical method and chemical method. The physical recycling procedure of PET product waste includes cleaning, crushing, granulation and other steps. However, the physical recycling method of PET waste cannot remove additives such as colorants, antioxidants, etc., and after repeated processing and remanufacturing, it is easy to cause plastic degradation, and recycled plastics can only be used in reduced grades.

The chemical recycling technology of waste PET products is to chemically depolymerize PET chains into monomers or various valuable chemical substances. When decomposing polyester chains, different chemical reagents (referred to as unchaining agents) have different depolymerization pathways. Basically, the chemical recycling technology of PET waste is to use a dechaining agent to break the ester group in the PET structure to degrade it into monomers such as diols, dibasic acids and dibasic amines. These depolymerized monomers can be recycled as raw materials for PET polymerization. According to the current PET depolymerization process chemical methods, there are mainly hydrolysis (including acidic hydrolysis, alkaline hydrolysis, neutral hydrolysis), alcoholysis (glycolysis) (including methanolysis, glycolysis) and aminolysis ( aminolysis).

The hydrolysis method used to depolymerize PET is to dissolve PET in alkaline, acidic and neutral aqueous environments with terephthalic acid (TPA) and ethylene glycol (EG). Since the hydrolysis reaction needs to add acid or alkali to treat the product, acid-base waste liquid pollutes the environment, and the reaction conditions are high-pressure process and long reaction time, the process cost is high and it is not easy to use in practical applications.

The alcoholysis method used to depolymerize PET is to add PET fragments into alcohol liquid in a certain proportion and heat for a period of time to depolymerize into monomers or oligomers. The dechaining agent used in alcoholysis to decompose polyester chains is usually low molecular weight diols, including methanol and ethylene glycol. If ethylene glycol is used for alcoholysis, the product is ethylene terephthalate (bis(2-hydroxyethyl) terephthalate, BHET) and its oligomers. If methanolysis is used, the products are dimethyl terephthalate (DMT) and ethylene glycol (EG). Glycolysis degrades PET into BHET and PET oligomers. Since these products can be mixed with BHET virgin materials and reused for PET manufacturing, they can also be further applied to PU foam, copolyester, hydrophobic dyes, unsaturated resins and acrylic coatings, so the ethylene glycol solution is the most effective method among the current methods. A recovery method of practical value. However, the slow reaction rate of low-pressure alcoholysis is its disadvantage. The methanolysis method is that PET can be degraded to form dimethyl terephthalate (DMT) and ethylene glycol (EG) under high temperature and high pressure methanol environment. Although the methanolysis method can be effectively applied to the recycling of waste bottles, waste fibers and membranes, its disadvantage is the high cost of separation and purification of reactants.

The aminolysis reaction of PET is to use ethylene glycol amine (ethanolamine) to aminolysis PET to produce bis-(2-hydroxyethylene) terephthalamide (bis-(2-hydroxyethylene) terephthalamide, BHETA). PET can generate bisamides through aminolysis, but this process has not been commercialized.

According to statistics, the global plastic recycling rate is only 12%, mostly physical recycling. The actual use of degradation methods to chemically recycle PET in the world accounts for less than 2% of the total PET recycling. This is mainly due to the fact that the cost of chemical recycling is much higher than that of physical recycling. To improve the recovery rate and economic benefits of high-molecular-weight polyester waste such as PET, it is necessary to make more efforts in innovative chemical recycling technologies, and improve the cost, process efficiency, product purity, catalysts, new products, and high-value applications. Overcome existing shortcomings.

化學結構如化學式(1)所示： 化學式(1) Regarding the previous technology of high-value products produced by depolymerized high-molecular-weight polyester, please refer to the Republic of China Patent Publication No. I613252. This prior art discloses a method for converting high-molecular-weight polyester into a thermoplastic elastomer. The steps include: ( 1) Add high molecular weight polyester and reactive oligomer to the reactor, wherein the reactive oligomer is selected from the group consisting of polypolyol (polyol) and polypolyamine (polyamine); (2) A catalyst is added to the reactor so that the reactive oligomer at least partially replaces the chemical structure (-O-R ₁ -O-) in the high molecular weight polyester, and the alcohol produced after the substitution is removed by vacuum distillation class (HO-R ₁ -OH); and (3) injecting the crude product into water to obtain a thermoplastic elastomer. The reactive oligomer is selected from the group consisting of polypolyol and polyamine. _In the case of using polyol alone, the _{thermoplastic} elastomer system obtained is thermoplastic polyester elastomer ( thermoplastic ester elastomer, TPEE); in the case of using polypolyamine alone, the obtained thermoplastic elastomer system is thermoplastic amide elastomer (thermoplastic amide elastomer, TPAE); and in the case of using a mixture of polypolyol and polypolyamine In some cases, the obtained thermoplastic elastomer system is thermoplastic amide-polyester elastomer (thermoplastic amide elastomer, TPAEE). The Republic of China patent announcement number I613252 discloses the obtained thermoplastic amide-polyester elastomer

The chemical structure is shown in chemical formula (1): Chemical formula (1)

於化學式(1)中，x於整體比例x/x+y+z係介於 0.5000~0.995之間；y於整體比例y/x+y+z係大於等於0並且小於0.500；z於整體比例z/x+y+z係大於0並且小於等於0.500；m係介於3~50之間；R1及R2係各自獨立地表示碳原子數1至6的支鏈或直鏈的亞烷基；R3係為碳原子數1至6的支鏈型或直鏈型亞烷基，或如下列結構： , , , 其中p及q係介3至70。

In the chemical formula (1), x in the overall ratio x/x+y+z is between 0.5000~0.995; y in the overall ratio y/x+y+z is greater than or equal to 0 and less than 0.500; z in the overall ratio z/x+y+z is greater than 0 and less than or equal to 0.500; m is between 3 and 50; R1 and R2 each independently represent a branched or straight chained alkylene group with 1 to 6 carbon atoms; R3 is a branched or linear alkylene group with 1 to 6 carbon atoms, or the following structure: , , , where p and q are between 3 and 70.

The Republic of China Patent Publication No. I613252 discloses a chemical method for converting high-molecular-weight polyesters into thermoplastic elastomers, and thermoplastic elastomers maintain the high molecular weight of the high-molecular-weight polyester polymer backbone. Taking PET as an example, the technology disclosed in the Republic of China Patent Publication No. I613252 is different from other prior technologies for depolymerization. It does not need to be degraded into PTA or DMT monomers and then restructured into polymers, which is a more advantageous process. It is believed that the depolymerization of high-molecular-weight polyesters into higher-value polymers without depolymerization into monomers can greatly increase the chemical recovery of high-molecular-weight polyesters through degradation. However, it still needs to be studied to depolymerize high-molecular-weight polyester into more polymers with higher value, so that the waste of high-molecular-weight polyester products can be chemically recycled in a degradative way as soon as possible.

Therefore, one technical problem to be solved by the present invention is to provide a high-molecular-weight dispersant transformed from depolymerized high-molecular-weight polyester and a manufacturing method thereof.

According to a preferred embodiment of the present invention, the polymer dispersant is obtained by depolymerizing high molecular weight polyester through polyol. The polymeric dispersant according to the present invention has a molecular weight ranging from 1,000 to 200,000 g/mol.

In a specific embodiment, the high molecular weight polyester can be polyethylene terephthalate (polyethylene terephthalate, PET), polytrimethylene terephthalate (polytrimethylene terephthalate, PPT), polybutylene terephthalate Diester (polybutylene terephthalate, PBT) or other high molecular weight polyester.

In a specific embodiment, the polypolyol can be polytetramethylene ether glycol (PTMEG), polypropylene glycol (poly(propylene glycol)), polyethylene glycol (poly(ethylene glycol), PEG ), polyether polyol, tri-functional polyoxypropylene polyol (tri-functional poly(oxypropylene), or a mixture of the above ingredients.

According to a method for producing a polymer dispersant in a preferred embodiment of the present invention, firstly, the high molecular weight polyester and polyol are depolymerized to produce polyester polyol and polyol. Then, according to the method of the present invention, the polyol is removed by distillation to obtain polyester polyol. Finally, according to the method of the present invention, the polyester polyol is subjected to a ring-opening reaction with an anhydride group to produce a polymer dispersant.

In practical application, the high molecular weight polyester undergoing depolymerization reaction can be wastes of various forms of high molecular weight polyester products, including wastes in the form of solid flakes, fibers, particles, powders and the like.

In practical applications, the polymer dispersant according to the present invention can be used to effectively disperse titanium dioxide (TiO ₂ ), red iron oxide (αFe ₂ O ₃ ), yellow iron oxide (αFeOOH), black iron oxide (Fe ₃ O ₄ ) and other inorganic powders. According to the polymer dispersant of the present invention, the inorganic powder can be manipulated in nanometer size, so as to facilitate the application of pigments, coatings, inks, textile dyeing, building materials, plastics, electronics, and biomedicine.

Different from the prior art, the present invention does not depolymerize high-molecular-weight polyester into monomers, but depolymerizes it into a water-soluble high-molecular dispersant with higher value. Moreover, the polymer dispersant of the present invention does not need to use highly volatile organic solvents in the manufacturing process, providing operators with a friendly working environment. The polymer dispersant of the present invention is well soluble in water and has a wide range of applications.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the accompanying drawings.

根據本發明之較佳具體實施例之高分子型分散劑係由高分子量的聚酯藉由聚多元醇解聚而得。根據本發明之高分子型分散劑具有如化學式(2)所示之結構： 化學式(2)

The polymer dispersant according to a preferred embodiment of the present invention is obtained by depolymerizing high molecular weight polyester through polyol. The polymer dispersant according to the present invention has a structure as shown in chemical formula (2): Chemical formula (2)

In the chemical formula (2), m is a natural number, and PEPO represents polyester polyol obtained by reacting high molecular weight polyester with polyol.

In a specific embodiment, the high molecular weight polyester can be polyethylene terephthalate (PET), polytrimethylene terephthalate (PPT), polybutylene terephthalate (PBT) or Other high molecular weight polyesters.

In a specific embodiment, the polypolyol can be polytetramethylene ether glycol (PTMEG), polypropylene glycol, polyethylene glycol (PEG), polyether polyol, trifunctional polyoxypropylene polyol or the above-mentioned components the mixture.

The polymeric dispersant according to the present invention has a molecular weight ranging from 1,000 to 200,000 g/mol.

According to a method for producing a polymer dispersant in a preferred embodiment of the present invention, firstly, the high molecular weight polyester and polyol are depolymerized to produce polyester polyol and polyol. The high molecular weight polyester may be polyethylene terephthalate (PET), polytrimethylene terephthalate (PPT), polybutylene terephthalate (PBT), or other high molecular weight polyesters. The polypolyol can be polytetramethylene ether glycol (PTMEG), polypropylene glycol, polyethylene glycol (PEG), polyether polyol, trifunctional polyoxypropylene polyol or a mixture of the above components.

In practical applications, the high molecular weight polyester undergoing depolymerization reaction can be recycled materials of various forms of waste of high molecular weight polyester products, including solid flakes, fibers, particles, powder and other forms of waste.

In a specific embodiment, the weight ratio of the high molecular weight polyester to the polypolyol ranges from 30:70 to 5:95.

In a specific embodiment, the reaction temperature range of the depolymerization reaction is 245-255°C.

In one embodiment, a first catalyst can be added to accelerate the depolymerization reaction. The first catalyst can be titanium, zinc, antimony, magnesium, aluminum, sodium, potassium, metal salts, organometallic compounds and the like.

Then, according to the method of the present invention, the polyol is removed by distillation to obtain polyester polyol.

Finally, according to the method of the present invention, the polyester polyol is subjected to a ring-opening reaction with an anhydride group to produce a polymer dispersant. Through the ring-opening reaction, the present invention further modifies the structure of the polyester polyol to form a structure with acid functional groups.

In a specific embodiment, the acid anhydride group can be trimellitic anhydride (trimellitic anhydride, TMA), bisphenol A dianhydride (4,4'-biphenol A dianhydride, BPADA), diphthalic anhydride (3,3',4, 4'-diphenylsulfone tetracarboxylic dianhydride, DSDA), 4,4'-oxydiphthalic dianhydride (4,4'-oxydiphthalic dianhydride, ODPA), 4,4'-hexafluorodianhydride (4,4'-( hexafluoroisopropylidene diphthalic anhydride, 6FDA), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (3,3'4,4'-biphenyl tetracarboxylic dianhydride, s-BPDA), pyromellitic dianhydride (pyromellitic dianhydride, PMDA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (3,3',4,4'-benzophenone tetracarboxylic dianhydride, BTDA), pyromellitic anhydride (pyromellitic anhydride) or Mixture of the above ingredients.

In a specific embodiment, the reaction temperature range of the ring-opening reaction is 190-210°C.

In one embodiment, a second catalyst can be added to accelerate the ring-opening reaction. The second catalyst may be p-toluenesulfonic acid (PTSA), etc., but the present invention is not limited thereto.

以聚對苯二甲酸乙二酯(PET)製品的廢棄物回收料與聚乙二醇(PEG)進行解聚反應，接著將生成的聚酯多元醇(PEPO)與偏苯三酸酐(TMA)進行開環反應作為說明，其反應式如化學反應式(3)所示： 化學反應式(3)

The waste recycling of polyethylene terephthalate (PET) products is depolymerized with polyethylene glycol (PEG), and then the resulting polyester polyol (PEPO) is ring-opened with trimellitic anhydride (TMA) Reaction as an illustration, its reaction formula is shown in chemical reaction formula (3): Chemical reaction formula (3)

In the chemical reaction formula (3), r-PET represents waste recycling of PET products, and r-PEPO represents polyester polyol obtained by depolymerization of r-PET. In the chemical structure of r-PEPO, the range of x/(x+y) is 0.05~0.3, and the range of y/(x+y) is 0.7~0.95. In particular, the structure of r-PEPO has a benzene ring, an ester group and a poly(oxyethylene) functional group. The structure of the polymer dispersant is the same as that of chemical formula (2), and only r-PEPO is used to replace PEPO in chemical formula (2) in the structure, so as to emphasize that it is derived from the polyester multiple alcohol.

再以聚對苯二甲酸丙二酯(PPT)製品的廢棄物回收料與聚乙二醇(PEG)進行解聚反應，接著將生成的聚酯多元醇(PEPO)與偏苯三酸酐(TMA)進行開環反應作為說明，其反應式如化學反應式(4)所示： 化學反應式(4)

Then, the waste recycling of polytrimethylene terephthalate (PPT) products is depolymerized with polyethylene glycol (PEG), and then the resulting polyester polyol (PEPO) is depolymerized with trimellitic anhydride (TMA). The ring reaction is used as an illustration, and its reaction formula is shown in chemical reaction formula (4): Chemical reaction formula (4)

In the chemical reaction formula (4), r-PPT represents the waste recyclate of PPT products, and r-PEPO represents the polyester polyol obtained by depolymerization of r-PPT. In the chemical structure of r-PEPO, the range of x/(x+y) is 0.05~0.3, and the range of y/(x+y) is 0.7~0.95. In particular, the structure of r-PEPO also has a benzene ring, an ester group and a poly(oxyethylene) functional group. The structure of the polymer dispersant is the same as that of chemical formula (2), and only r-PEPO is used to replace PEPO in chemical formula (2) in the structure, so as to emphasize that it is derived from the polyester multi-component obtained from the depolymerization of waste recycled materials of PPT products. alcohol.

再以聚對苯二甲酸丁二酯(PBT)製品的廢棄物回收料與聚乙二醇(PEG)進行解聚反應，接著將生成的聚酯多元醇(PEPO)與偏苯三酸酐(TMA)進行開環反應作為說明，其反應式如化學反應式(5)所示： 化學反應式(5)

Then, the waste recycling of polybutylene terephthalate (PBT) products is depolymerized with polyethylene glycol (PEG), and then the resulting polyester polyol (PEPO) is depolymerized with trimellitic anhydride (TMA). The ring reaction is used as an illustration, and its reaction formula is shown in chemical reaction formula (5): Chemical reaction formula (5)

In the chemical reaction formula (5), r-PBT represents the waste recyclate of PBT products, and r-PEPO represents the polyester polyol obtained by depolymerization of r-PBT. In the chemical structure of r-PEPO, the range of x/(x+y) is 0.05~0.3, and the range of y/(x+y) is 0.7~0.95. In particular, the structure of r-PEPO also has a benzene ring, an ester group and a poly(oxyethylene) functional group. The structure of the polymer dispersant is the same as that of chemical formula (2), and only r-PEPO is used to replace PEPO in chemical formula (2) in the structure, so as to emphasize that it is derived from the polyester multi-component obtained from the depolymerization of waste recycled materials of PBT products. alcohol.

In practical application, the polymer dispersant according to the present invention is soluble in water and can be used to effectively disperse titanium dioxide (TiO ₂ ), red iron oxide (αFe ₂ O ₃ ), yellow iron oxide (αFeOOH), iron oxide Inorganic powders such as black (Fe ₃ O ₄ ). According to the polymer dispersant of the present invention, the inorganic powder can be manipulated in nanometer size, so as to facilitate the application of pigments, coatings, inks, textile dyeing, building materials, plastics, electronics, and biomedicine. The primary particle size of inorganic powders generally used in the above applications ranges from 0.1 to 100 μm.

It should be emphasized that, unlike the Republic of China Patent Publication No. I613252, which discloses that high-molecular-weight polyesters are depolymerized into thermoplastic polyester elastomers (TPEE) when polypolyols are used alone, the method according to the present invention also converts high-molecular-weight polyesters into thermoplastic polyester elastomers (TPEE). The polyester of molecular weight is converted into polyester polyol (PEPO) using polypolyol depolymerization, but, the parameter of the present invention's control depolymerization reaction, the condition are different from the parameters and conditions of the control depolymerization reaction of the Republic of China patent announcement number I613252, including High molecular weight polyester/polyol ratio, reaction temperature, etc. The chemical structure of the polyester polyol (PEPO) obtained in the present invention is different from that of the thermoplastic polyester elastomer (TPEE) obtained in the patent announcement number I613252 of the Republic of China, and the polyester polyol (PEPO) obtained in the present invention is not the final product , followed by a ring-opening reaction to modify the functional group to generate a water-soluble chemical dispersant. It is emphasized again that the thermoplastic polyester elastomer (TPEE) obtained in the Republic of China Patent Publication No. I613252 is not soluble in water.

In Example 1, the process according to the preferred embodiment of the present invention was performed in a three-neck reactor with mechanical stirrer, heating mantle, Dean-Stark Trap and water-cooled condenser , filled with PEG-1000 (100 g) and titanium catalyst (as a catalyst, the amount added is 400 ppm of the weight of the final product), and heated to 150°C. While stirring, recycled PET regrind (25 g) was added thereto in batches. With stirring and heating, the flakes of PET regrind slowly dissolve and allow more flakes to be added. The PET recycled material is added in batches according to the dissolution rate. Gradually, the temperature was raised up to 250°C until all the PET flakes were dissolved in the PEG. Subsequently, ethylene glycol (EG) with a lower boiling point (196° C.) replaced by polyether diol in the reactor was removed through a Dean-Stark separator. At 250°C, EG was apparently completely removed over a period of 4 hours. The reaction product was then poured into a flask with deionized water and the insolubles removed. The product was concentrated under reduced pressure to remove water to obtain a polyester polyol (r-PEPO); in a 250 ml three-necked bottle, r-PEPO (100 g) was added, followed by TMA (19.2 g) for ring opening For the reaction, the molar ratio of TMA/r-PEPO was 1:1. The mixture was mechanically stirred, filled with nitrogen throughout the process, and reacted at room temperature for four hours. After adding PTSA (as a catalyst) (0.2 g, 0.2 wt%), it was heated to 200 ° C and reacted for 2 hours to obtain a polyester polymer Dispersant. Next, take a polymer dispersant (0.7 g) and add it to 6.3 g of water. After it is uniformly dissolved, add 7.0 g of titanium dioxide powder (with a particle size ranging from 190 to 200 nm) and stir evenly, and analyze it by a particle size analyzer. The average particle size of the particles in the molecular dispersant solution is 230nm.

As a control, titanium dioxide powder was directly added into pure water to observe its dispersion. Please refer to Fig. 1, Fig. 1 is the photograph of the appearance of the comparative example in which titanium dioxide powder is added into water. In Figure 1, the plastic tank on the left contains titanium dioxide powder, and the glass beaker on the right contains pure water added with titanium dioxide powder. It can be seen with the naked eye that the titanium dioxide powder in the glass beaker in Figure 1 is not uniformly dispersed in pure water. Please refer to FIG. 2. FIG. 2 is a photograph of the appearance of titanium dioxide powder added to the polymer dispersant solution of Example 1 of the present invention. In Fig. 2, the plastic tank on the left contains titanium dioxide powder, and the glass beaker on the right contains the polymer dispersant solution of Example 1 added with titanium dioxide powder. It can be seen with the naked eye that the titanium dioxide powder in the glass beaker in Figure 2 is uniformly dispersed in the polymer dispersant solution of Example 1.

Please refer to Fig. 3 and Fig. 4, Fig. 3 is a TEM photograph of a comparative example in which titanium dioxide powder was added into pure water. Fig. 4 is a TEM photo of a sample obtained by adding titanium dioxide powder to the polymer dispersant solution of Example 1 of the present invention. The TEM photo in Figure 3 and confirms that the aggregation of titanium dioxide powder in pure water is obvious. The TEM photo of Fig. 4 confirms that the aggregation of titanium dioxide powder in the polymer dispersant solution is very slight, that is to say, the polymer dispersant solution of Example 1 of the present invention can effectively and evenly disperse inorganic powders such as titanium dioxide body.

The reaction parameters and conditions controlled by Embodiment 2, Embodiment 3, Embodiment 4, Embodiment 5 and Embodiment 6 of the present invention are mostly the same as the reaction parameters and conditions of Embodiment 1 of the present invention. , The depolymerization reaction time is different. The reaction parameters and condition series of each embodiment are listed in Table 1. The polymer dispersant solution obtained in each embodiment was used to disperse titanium dioxide powder, and the average particle size of the particles in the polymer dispersant solution was analyzed by a particle size analyzer, which is also listed in Table 1.

The PEG consumption of all examples listed in table 1 is all the same, the PET charging amount of embodiment 1, embodiment 2 and embodiment 3 is appropriate, the PET charging amount of embodiment 5 is suitably less, the PET charging amount of embodiment 4 is more , the PET charging capacity of embodiment 6 is then too much. The depolymerization reaction time of embodiment 1, embodiment 4, embodiment 5 and embodiment 6 is 4 hours, the depolymerization reaction time of embodiment 2 is 2 hours, and the depolymerization reaction time of embodiment 3 is 6 hours.

Table 1 Condition example PEG (g) PET (g) Depolymerization reaction time (hours) The average particle size of titanium dioxide powder after dispersion (nm) Example 1 100 25 4 230 Example 2 100 25 2 410 Example 3 100 25 6 290 Example 4 100 42.8 4 660 Example 5 100 11.1 4 290 Example 6 100 66.7 4 It cannot be dissolved in water and cannot be used as a dispersant.

The polymer dispersant solution obtained in Example 1, Example 3 and Example 5 all has a good dispersion effect on inorganic powders such as titanium dioxide, which also proves that the present invention does not depolymerize high-molecular-weight polyester into monomers, and instead Depolymerization transforms into a water-soluble polymer dispersant with higher value. In Example 2, due to the short depolymerization reaction time, the obtained polymer dispersant solution has a poor dispersion effect on inorganic powders such as titanium dioxide. In Example 4, the structure of the product obtained in the depolymerization reaction may change due to the large amount of PET, resulting in the resulting macromolecule Type dispersant solution has a very poor dispersion effect on inorganic powders such as titanium dioxide. In Example 6, due to the excessive amount of PET, the chemical structure obtained by the depolymerization reaction is not the desired chemical structure of the present invention and finally produces a product that cannot be dissolved in water.

From the above detailed description of the preferred specific embodiments, it is believed that it can be clearly understood that the present invention does not depolymerize the high molecular weight polyester into monomers, but depolymerizes it into a water-soluble polymer dispersant with higher value. Moreover, the polymer dispersant of the present invention does not need to use highly volatile organic solvents in the manufacturing process, providing operators with a friendly working environment. The polymer dispersant of the present invention is well soluble in water and has a wide range of applications.

Through the above detailed description of the preferred embodiments, it is hoped that the characteristics and spirit of the present invention can be described more clearly, and the aspect of the present invention is not limited by the preferred embodiments disclosed above. On the contrary, the purpose is to cover various changes and equivalent arrangements within the scope of the patent application for the present invention. Therefore, the aspect of the scope of the patent application for the present invention should be interpreted in the broadest way based on the above description, so as to cover all possible changes and equivalent arrangements.

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Fig. 1 is a photograph of the appearance of a comparative example in which titanium dioxide powder is added to pure water. Fig. 2 is a photograph of the appearance of titanium dioxide powder added to the polymer dispersant solution of Example 1 of the present invention. Fig. 3 is a transmission electron microscope (TEM) photograph of a comparative example in which titanium dioxide powder was added into pure water. Fig. 4 is a TEM photo of a sample obtained by adding titanium dioxide powder to the polymer dispersant solution of Example 1 of the present invention.

Claims (9)

A polymer dispersant is obtained by depolymerizing a high-molecular-weight polyester with a polypolyol. The polymer dispersant has a structure as shown in formula (I):

Wherein m is a natural number, PEPO represents a polyester polyol obtained by reacting the high molecular weight polyester with the polypolyol, and the polymer dispersant has a molecular weight ranging from 1,000 to 200,000 g/mol. The polymer type dispersant as described in claim 1, wherein the high molecular weight polyester is selected from polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate One of the formed groups. The polymer dispersant as described in claim 2, wherein the polypolyol is selected from polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, polyether polyol, trifunctional polyoxypropylene polyol and one of the group consisting of mixtures of the above ingredients. A method for producing a polymer dispersant, comprising the following steps: (a) carrying out a depolymerization reaction with a high molecular weight polyester and a polypolyol to produce a polyester polyol and a polyol, wherein The high molecular weight polyester is selected from one of the group consisting of polyethylene terephthalate, polytrimethylene terephthalate and polybutylene terephthalate, and the polypolyol is One selected from the group consisting of polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, polyether polyol, trifunctional polyoxypropylene polyol and mixtures of the above ingredients, the high molecular weight A ratio of the weight of the polyester to the polyol is in the range of 30:70 to 5:95; (b) removing the polyol by a distillation method to obtain the polyester polyol; and; (c) carrying out a ring-opening reaction with polyester polyol and an anhydride group to produce the polymer dispersant, wherein the polymer dispersant has a structure as shown in formula (I):

Wherein m is a natural number, PEPO represents the polyester polyol, and the polymer dispersant has a molecular weight ranging from 1,000 to 200,000 g/mol. The method according to claim 4, wherein in step (a), the first reaction temperature range of the depolymerization reaction is 245~255°C. The method as claimed in claim 5, wherein in step (a), a first catalyst is added, the first catalyst is selected from the group consisting of titanium, zinc, antimony, magnesium, aluminum, sodium, potassium, metal salts and organic One of the group consisting of metal compounds. The method as described in claim item 6, wherein the acid anhydride group is selected from trimellitic anhydride, bisphenol A dianhydride, diphthalic anhydride, 4,4'-oxydiphthalic anhydride, 4,4'-hexafluoro Dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic acid One of the group consisting of dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, pyromellitic anhydride, and mixtures of the above components. The method as described in Claim 5, wherein in step (c), the second reaction temperature range of the ring-opening reaction is 190~210°C. The method as described in claim item 5, wherein in step (c), a second catalyst is added, and the second catalyst is p-toluenesulfonic acid.

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