Method for producing bio-pet resin

Abstract

To provide a method for producing a bio-PET resin derived substantially 100% from a biomass resource, using a raw material derived from a carbon-neutral biomass resource as much as possible in place of a raw material derived from a petroleum resource.SOLUTION: Ethylene glycol derived from a biomass resource is polymerized with terephthalic acid derived from a biomass resource in the presence of a catalyst containing an aluminum compound or germanium compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing polyethylene terephthalate resin derived from biomass resources using an aluminum compound or a germanium compound as a catalyst, and a method for producing PET products (e.g., PET bottles) that includes processing the PET resin. [Background technology]

[0002] Polyethylene terephthalate (PET) resin is a crystalline resin obtained by polycondensation of ethylene glycol and terephthalic acid as its main components, and is consumed in large quantities as a material for containers (especially PET bottles for soft drinks) for beverages, foods, cosmetics, pharmaceuticals, detergents, etc., due to its excellent moldability, heat resistance, chemical resistance, transparency, mechanical strength, and gas barrier properties. However, most of this resin is derived from petroleum resources. In recent years, in consideration of environmental issues such as global warming caused by carbon dioxide emissions and the depletion of petroleum resources, regulations regarding the environmental impact of industrial activities have become stricter, and there has been a global increase in demand for PET resin derived from carbon-neutral biomass resources (hereinafter referred to as "bio-PET resin") instead of petroleum resources.

[0003] A method for producing polyethylene terephthalate multi-component glycol copolymer polyester fiber using corn-derived ethylene glycol has been reported (Patent Document 1). However, biomass resources contain trace amounts of biologically derived impurities such as proteins and metal cations, and are poor in polymerization reactivity and transparency, making their commercialization into PET resin difficult. Therefore, there are no known successful examples of the production of bio-PET resin derived essentially 100% from biomass resources. In fact, the bio-PET resin currently on the market is merely one in which approximately 30% by weight of ethylene glycol, one of its main components, is produced from raw materials derived from sugarcane (known as "bio-PET resin 30"). Therefore, there is a need for the development of bio-PET resins with an even higher proportion of raw materials derived from biomass resources. Patent Document 2 discloses a method for producing a PET product, including a step of forming at least one component, ethylene glycol or terephthalic acid, from a bio-based material. However, this document does not teach any issues, such as polymerization reactivity and transparency, in the production of PET resin derived from biomass resources, or how these issues can be resolved. Even if the PET product disclosed in this document is produced using raw materials in which both ethylene glycol and terephthalic acid are derived from biomass resources, PET products such as PET bottles for aseptic filling typically contain isophthalic acid, cyclohexanedimethanol, or diethylene glycol as copolymerization components in addition to the main components, monoethylene glycol and terephthalic acid, to impart heat resistance, and therefore cannot be said to be a bio-PET resin derived substantially 100% from biomass resources. For example, copolymer components such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol contained in PET resin account for only a few weight percent (0.1 to 3 weight percent), but considering the enormous amount of PET resin consumed worldwide, even trace amounts of components in PET resin cannot be ignored. For this reason, it is conceivable to produce copolymer components such as isophthalic acid from raw materials derived from biomass resources, but this is not realistic because the production costs would be extremely high. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent Application Publication No. 101046007 [Patent Document 2] Patent No. 5784510 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-249466 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-323676 [Patent Document 5] Japanese Patent Application Laid-Open No. 2006-52393 [Patent Document 6] Japanese Patent Application Laid-Open No. 2007-2239 [Patent Document 7] Japanese Patent Application Laid-Open No. 2008-266359 [Patent Document 8] Japanese Patent Application Laid-Open No. 2008-266360 [Patent Document 9] Japanese Patent Application Laid-Open No. 2010-235941 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a method for producing bio-PET resin that is substantially 100% derived from biomass resources, using raw materials derived from carbon-neutral biomass resources as much as possible instead of raw materials derived from petroleum resources. [Means for solving the problem]

[0006] The present inventors have conducted extensive research and experiments to solve the above-mentioned problems, and as a result have made the surprising discovery that a bio-PET resin suitable for use in PET products (particularly PET bottles) can be produced without adding a copolymerization component such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol as a copolymerization component by using an aluminum compound or a germanium compound as a catalyst in the polymerization process of ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource, and have thus completed the present invention.

[0007] The present invention is as follows. [1] A method for producing bio-PET resin, comprising the step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource in the presence of a catalyst containing an aluminum compound or a germanium compound. [2] The method according to claim 1, wherein no copolymerization component is added. [3] The method according to 2, wherein the copolymerization component is isophthalic acid, cyclohexanedimethanol, or diethylene glycol. [4] The method according to 1, wherein the aluminum compound is an organoaluminum compound selected from aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum acetylacetonate, aluminum acetylacetonate, aluminum oxalate, aluminum oxide, or an alkylaluminum, or a partial hydrolyzate thereof, or a combination thereof. [5] The method according to 1, wherein the germanium compound is germanium tetroxide, germanium tetraethoxide, germanium tetra-n-butoxide, crystalline germanium dioxide, amorphous germanium dioxide, germanium hydroxide, germanium oxalate, germanium chloride, or germanium phosphite, or a combination thereof. [6] The method according to any one of 1 to 5, wherein the biomass resource is a carbohydrate material selected from sugarcane, molasses, or sugar beet; a starchy material selected from corn, sorghum, potato, sweet potato, wheat, or cassava; a cellulosic plant-derived material selected from pulp waste, bagasse, waste wood, wood chips, rice husks, rice straw, fruit fiber, fruit kernel shells, or empty fruit bunches; a natural fiber product or waste thereof; or a combination thereof. [7] The method according to any one of 1 to 6, wherein the step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource comprises suspension polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource to produce bis(β-hydroxyethyl) terephthalate (BHET) and / or an oligomer thereof as an intermediate, and melt polycondensing the BHET and / or an oligomer thereof obtained in the presence of the catalyst. [8] The method according to 7, further comprising processing the bio-PET resin obtained by melt polycondensation into pellets and then solid-state polymerizing the pellets. [9] The method according to any one of 1 to 8, wherein the bio-PET resin has an intrinsic viscosity (IV) of 0.7 to 0.85 dl / g.

[10] The method according to any one of 1 to 9, characterized in that more than 97% by weight of the components of the bio-PET resin are derived from biomass resources.

[11] The method according to claim 10, wherein more than 99% by weight of the components of the bio-PET resin are derived from biomass resources.

[12] The method according to claim 11, wherein more than 99.9% by weight of the components of the bio-PET resin are derived from biomass resources.

[13] A method for producing a PET product, comprising providing a bio-PET resin by the method according to any one of 1 to 12, and processing the bio-PET resin into a PET product.

[14] The method according to 13, characterized in that the PET product is a PET bottle.

[15] Use of a catalyst containing an aluminum compound or a germanium compound in the production of bio-PET resin derived from biomass resources.

[16] The use according to 15, characterized in that no copolymerization component is added in the production of bio-PET resin derived from biomass resources.

[17] The use according to 16, wherein the copolymerization component is isophthalic acid, cyclohexanedimethanol, or diethylene glycol.

[18] The use according to 15, wherein the aluminum compound is an organoaluminum compound selected from aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum acetylacetonate, aluminum acetylacetonate, aluminum oxalate, aluminum oxide, or an alkylaluminum, or a partial hydrolyzate thereof, or a combination thereof.

[19] The use according to 15, wherein the germanium compound is germanium tetroxide, germanium tetraethoxide, germanium tetra-n-butoxide, crystalline germanium dioxide, amorphous germanium dioxide, germanium hydroxide, germanium oxalate, germanium chloride, or germanium phosphite, or a combination thereof.

[20] The use according to any one of 15 to 19, wherein the biomass resource is a carbohydrate material selected from sugarcane, molasses, or sugar beet; a starchy material selected from corn, sorghum, potato, sweet potato, wheat, or cassava; a cellulosic plant-derived material selected from pulp waste, bagasse, waste wood, wood chips, rice husks, rice straw, fruit fiber, fruit kernel shells, or empty fruit bunches; a natural fiber product or waste thereof; or a combination thereof.

[21] The use according to any one of 15 to 20, wherein the production of the bio-PET resin derived from a biomass resource comprises a step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource, and the step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource comprises suspension polymerization of ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource to produce bis(β-hydroxyethyl) terephthalate (BHET) and / or an oligomer thereof as an intermediate, and melt polycondensation of the BHET and / or an oligomer thereof obtained in the presence of the catalyst.

[22] The use according to 21, wherein the production of the bio-PET resin derived from biomass resources further comprises processing the bio-PET resin obtained by melt polycondensation into pellets and subjecting the pellets to solid-state polymerization.

[23] The use according to any one of 15 to 22, wherein the bio-PET resin has an intrinsic viscosity (IV) of 0.7 to 0.85 dl / g.

[24] The use according to any one of 15 to 23, characterized in that more than 97% by weight of the components of the bio-PET resin are derived from biomass resources.

[25] The use according to 24, characterized in that more than 99% by weight of the components of the bio-PET resin are derived from biomass resources.

[26] The use according to 25, characterized in that more than 99.9% by weight of the components of the bio-PET resin are derived from biomass resources. [Effects of the Invention]

[0008] The present invention provides a PET resin that uses, as much as possible, raw materials derived from carbon-neutral biomass resources instead of raw materials derived from petroleum resources. The bio-PET resin obtained by the present invention has properties equivalent to those of conventional PET resins derived from petroleum resources, so it can be processed into PET products such as PET bottles using existing equipment and can be recycled together with conventional PET resins. [Brief explanation of the drawings]

[0009] [Figure 1] 1 shows a typical production scheme of the bio-PET resin of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Biomass resources are generally defined as renewable, biologically derived organic resources, excluding petroleum resources. Because biomass resources are organic, they emit carbon dioxide when burned. However, the carbon contained in them comes from carbon dioxide absorbed from the atmosphere by the organisms that produce the biomass through photosynthesis and other processes during their growth. Therefore, even when using biomass resources, they do not increase the amount of carbon dioxide in the atmosphere overall (i.e., they are carbon neutral). Based on this concept, they do not increase the overall concentration of carbon dioxide in the atmosphere, and therefore do not contribute to global warming. Furthermore, unlike fossil resources such as petroleum, biomass resources can be used without depletion if properly managed.

[0011] The biomass resource is not particularly limited as long as ethylene glycol and / or terephthalic acid can be obtained, and may be a waste-based biomass resource (e.g., paper, livestock manure, food waste, construction waste, black liquor, sewage sludge, food waste, etc.) or an unused biomass resource (e.g., rice straw, wheat straw, rice husks, forest residues, resource crops, feed crops, starch-based crops, etc.). Specifically, these include carbohydrate raw materials (sugarcane, molasses, sugar beet, etc.), starch raw materials (corn, sorghum, potato, sweet potato, wheat, cassava, etc.), and other cellulosic plant-derived raw materials (pulp waste liquid, bagasse, waste wood, wood chips, rice husks, rice straw, fruit fiber, fruit kernel shells, empty fruit bunches), as well as natural fiber products or their waste (including unused items such as surplus stock) such as miscellaneous goods and daily necessities containing cotton or linen (towels, handkerchiefs, clothing, stuffed toys, curtains, etc.).

[0012] Biomass-derived ethylene glycol and biomass-derived terephthalic acid, which are raw materials for bio-PET resin, can be produced using known methods such as catalytic flash pyrolysis, liquid-phase reforming, catalytic chemical conversion, acid hydrolysis, enzymatic hydrolysis, microbial degradation, fermentation-derived conversion, bacterial degradation, and hydrogenolysis. For example, biomass-derived ethylene glycol can be obtained by fermenting biomass to extract bioethanol, converting the resulting bioethanol to ethylene, and then converting it to ethylene oxide and then to ethylene glycol. Biomass-derived terephthalic acid can be obtained by catalytic flash pyrolysis of biomass to produce xylene, followed by separation, purification, and isomerization to produce paraxylene, and then subjecting the paraxylene to a liquid-phase oxidation reaction.

[0013] Bio-PET resin is produced by polymerizing ethylene glycol derived from the biomass resource and terephthalic acid derived from the biomass resource in the presence of a catalyst containing an aluminum compound or a germanium compound.

[0014] Conventional PET resin manufacturing methods use antimony compounds such as antimony trioxide, which are inexpensive and have excellent catalytic activity, or titanium compounds, which are safe and highly reactive. However, when using antimony or titanium compounds, the amount of these compounds added during polymerization must be increased, resulting in increased residues in the PET resin and a rapid crystallization rate. This can lead to a loss of transparency and to properties (e.g., heat resistance and pressure resistance) that are not suitable for bottle applications. Therefore, in addition to the main polymerization components such as monoethylene glycol and terephthalic acid, it is necessary to add copolymerization components such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol to suppress excessive crystallization. Although the copolymerization components such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol contained in PET resin account for only a few weight percent (0.1–3 wt%), considering the enormous amount of PET resin consumed worldwide, even trace amounts of these components would clearly contribute significantly to the global environment if we could avoid the use of petroleum-derived raw materials in its production. The present inventors have now surprisingly discovered that the use of aluminum or germanium compounds with relatively high catalytic activity as catalysts makes it possible to avoid the addition of copolymerization components such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol in the production of bio-PET resin. While it has been known that aluminum and germanium compounds are used as polyester polymerization catalysts in the production of PET resins from petroleum-derived raw materials (Patent Documents 3 to 9), no attempts have been made to use these catalysts to avoid the addition of copolymerization components such as isophthalic acid, cyclohexanedimethanol, and diethylene glycol and produce bio-PET resins derived essentially entirely from biomass resources. Furthermore, it has been found that the use of aluminum or germanium compounds as catalysts increases the transparency and intrinsic viscosity (IV) retention of PET resins compared to the use of other catalysts such as antimony or titanium compounds. These properties are also advantageous for processing into PET products and recycling.

[0015] Examples of aluminum compounds used in the present invention include, but are not limited to, organoaluminum compounds such as aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum acetylacetonate, aluminum acetylacetonate, aluminum oxalate, aluminum oxide, and alkylaluminum, as well as partial hydrolysates thereof. The aluminum compound is used so that the content of aluminum atoms in the resin is typically about 1 to about 50 ppm, preferably about 3 to about 40 ppm, and optimally about 10 to about 20 ppm.

[0016] The germanium compound used in the present invention includes, but is not limited to, germanium tetroxide, germanium tetraethoxide, germanium tetra-n-butoxide, crystalline germanium dioxide, amorphous germanium dioxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium phosphite, etc. The germanium compound is used so that the content of germanium atoms in the resin is typically about 1 ppm to 100 ppm.

[0017] The polymerization process for bio-PET resin can be carried out using conventionally known processes. For example, as shown in FIG. 1, the process involves suspension polymerization of biomass-derived ethylene glycol (liquid) and biomass-derived terephthalic acid (powder) to obtain bis(β-hydroxyethyl) terephthalate (BHET) and / or its oligomers as an intermediate, followed by melt polycondensation of the resulting BHET by dehydration at approximately 270 to 300°C under high vacuum in the presence of a catalyst containing an aluminum compound or a germanium compound. The catalyst containing an aluminum compound or a germanium compound can be added to the reaction system at any stage of the polymerization reaction. For example, the catalyst can be added to the reaction system before or during the initiation of the esterification reaction or transesterification reaction, or immediately before or during the initiation of the polycondensation reaction. However, it is preferable to add the catalyst immediately before the initiation of the polycondensation reaction. The catalyst can be added in powder or neat form, or in the form of a slurry or solution in a solvent such as biomass-derived ethylene glycol, and is not particularly limited. The melt polycondensation reaction may be carried out in a batch reactor or a continuous reactor, and may be carried out in one stage or in multiple stages.

[0018] In addition, a phosphorus compound may be added as a stabilizer to prevent yellowing. Examples of the phosphorus compound include phosphoric acid or phosphoric acid ester, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinous acid compounds, and phosphine compounds. The phosphorus compound may be added to the polymerization system simultaneously with the catalyst, or they may be added at different times.

[0019] The bio-PET resin obtained by melt polycondensation is extruded and processed into pellets using a pelletizer, resulting in transparent pellets.

[0020] For applications requiring low acetaldehyde content and low cyclic trimer content, such as in beverage bottle applications, particularly heat-resistant blown moldings for low-flavor beverages and mineral water, the melt-polycondensed polyester thus obtained is subjected to solid-state polymerization. The solid-state polymerization reaction, like the melt-polycondensation reaction, can be carried out using a batch or continuous apparatus, and may be run continuously with the melt-polycondensation step, or may be run separately. The pellets are pre-crystallized (white pellets: to prevent fusion of pellets during solid-state polymerization) by heating for a certain period of time at a temperature of 100 to 210°C under an inert gas atmosphere or reduced pressure, or under a water vapor or water vapor-containing inert gas atmosphere. Next, solid-state polymerization is carried out for a certain period of time at a temperature of 190 to 230°C under an inert gas atmosphere or reduced pressure.

[0021] Solid-state polymerization allows the molecules of PET resin to polymerize together, increasing strength and reducing impurities such as acetaldehyde and cyclic oligomers contained in the raw resin.

[0022] In this way, by avoiding the addition of copolymerization components such as isophthalic acid, cyclohexanedimethanol, or diethylene glycol, a bio-PET resin derived substantially 100% from biomass resources can be obtained. "Substantially 100% derived from biomass resources" means that more than 97 wt. %, preferably more than 98 wt. %, more preferably more than 99 wt. %, and most preferably more than 99.9 wt. % of the components of the resulting bio-PET resin are derived from biomass resources. Furthermore, the resulting bio-PET resin has excellent transparency and intrinsic viscosity (IV) retention, making it extremely useful as a material for PET products such as PET bottles.

[0023] By processing bio-PET resin into PET products using known methods, high-value-added PET products can be produced. Examples of such PET products include, but are not limited to, containers for beverages, foods, cosmetics, pharmaceuticals, detergents, etc. (especially PET bottles for soft drinks), as well as photographic film, cassette tapes, and clothing fibers such as fleece. Examples of PET bottles for soft drinks include heat-resistant PET bottles, aseptic filling PET bottles, pressure-resistant PET bottles, and heat- and pressure-resistant pot bottles.

Claims

1. A method for producing a bio-PET resin for PET bottles, the method comprising: The method includes a step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource in the presence of a catalyst containing an aluminum compound or a germanium compound, The aluminum compound is used so that the content of aluminum atoms in the resin is 1 to 50 ppm, The germanium compound is used so that the content of germanium atoms in the resin is 1 ppm to 100 ppm, In the method, no copolymerization component is added, and the copolymerization component is isophthalic acid, cyclohexanedimethanol, or diethylene glycol; The intrinsic viscosity (IV) of the bio-PET resin is 0.7 to 0.85 dl / g; the aluminum compound is an organoaluminum compound selected from aluminum acetate, aluminum lactate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum acetylacetonate, aluminum acetylacetonate, aluminum oxalate, aluminum oxide, or an alkylaluminum, or a partial hydrolyzate thereof, or a combination thereof; the germanium compound is germanium tetraethoxide, germanium tetra-n-butoxide, crystalline germanium dioxide, amorphous germanium dioxide, germanium hydroxide, germanium oxalate, germanium chloride, or germanium phosphite, or a combination thereof; the step of polymerizing ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource further comprises: producing bis(β-hydroxyethyl) terephthalate (BHET) and / or an oligomer thereof as an intermediate by suspension polymerization of ethylene glycol derived from a biomass resource and terephthalic acid derived from a biomass resource; melt-polycondensing the BHET and / or an oligomer thereof obtained in this manner in the presence of the catalyst; and processing the bio-PET resin obtained by melt-polycondensation into pellets and solid-state polymerizing the pellets; 10. The method of claim 9, wherein greater than 97% by weight of the components of the bio-PET resin are derived from biomass resources.

2. 2. The method according to claim 1, wherein the biomass resource is a carbohydrate material selected from sugarcane, molasses, or sugar beet; a starchy material selected from corn, sorghum, potato, sweet potato, wheat, or cassava; a cellulosic plant-derived material selected from pulp waste, bagasse, waste wood, wood chips, rice husks, rice straw, fruit fiber, fruit kernel shells, or empty fruit bunches; a natural fiber product or waste thereof; or a combination thereof.

3. 3. The method according to claim 1 or 2, characterized in that more than 99% by weight of the components of the bio-PET resin are derived from biomass resources.

4. 4. The method of claim 3, wherein more than 99.9% by weight of the components of the bio-PET resin are derived from biomass resources.

5. A method for producing a PET bottle, comprising providing a bio-PET resin according to the method of any one of claims 1 to 4, and processing the bio-PET resin into a PET product.