WO2024141801A1

WO2024141801A1 - Process for preparing an aqueous-based biodegradable polymer dispersion composition

Info

Publication number: WO2024141801A1
Application number: PCT/IB2023/058270
Authority: WO
Inventors: Anupat POTISATITYUENYONG; Chutamart PITAKCHATWONG; Narakorn CHANPRASERT; Pawanna KOSOLJITKUL
Original assignee: PTT Global Chemical PCL
Current assignee: PTT Global Chemical PCL
Priority date: 2022-12-28
Filing date: 2023-08-18
Publication date: 2024-07-04
Anticipated expiration: 2025-06-28

Abstract

The present invention relates to a process for preparing an aqueous-based biodegradable polymer dispersions composition, comprising the following steps: (a) mixing biopolymer, plasticizer, stabilizer, and aqueous solution in a stir tank reactor at the temperature from 90 to 150 °C and pressure from 3 to 5 bars until the biodegradable polymer composition becomes homogeneous; (b) subjecting mixture in step (a) to reflux pressurization system to disperse said mixture into small particles and reflux back to the stir tank reactor; and (c) reducing the temperature of the stir tank reactor down to the temperature from 25 to 40 °C to obtain the stable aqueous-based biodegradable polymer dispersions composition.

Description

PROCESS FOR PREPARING AN AQUEOUS-BASED BIODEGRADABLE

POLYMER DISPERSION COMPOSITION

TECHNICAL FIELD

The present invention relates to the process for preparing an aqueous-based biodegradable polymer dispersions composition.

BACKGROUND ART

An aqueous-based biodegradable polymer dispersion has been used as an environmentally friendly coating material for packaging coating, plastic, and paper cup. It can be used as a substitute material for the packaging coating obtained from petroleum that has a problem in recycling and is biodegradable after use.

At present the biodegradable polymer has been used as a surface coating in an extrusion coating method. However, there are limitations to the extrusion of biodegradable polymer because the use of a screw extruder requiring a high temperature and a high shear force in the coating process, which accumulates heat and degrades the polymer during the coating process. Moreover, the extrusion coating method requires the thick coating to provide high binding strength, which consumes a high amount of the resin in the production cost. Therefore, the use of the biodegradable polymer in a small amount that has good dispersibility in water is an alternative to address said problem.

Hence, the dispersion of the aqueous-based biodegradable polymer existing at present has limitations in terms of requiring multiple preparation steps, specific equipment in the production and using toxic volatile organic compounds (VOCs) which cannot be used for food packaging. Moreover, the existing coating technology has a low binding strength and a low liquid resistance which can be detached from the surface easily during use.

WO20212335351 discloses the preparation process for an aqueous dispersion of a biodegradable polyester prepared by a transesterification of biodegradable polyester and polyethylene glycol. The biodegradable polyester was mixed, melted, and then subjected to transesterification with a catalyst to obtain the aqueous-based biodegradable polymer. However, the said process requires a chemical reaction and catalyst which modifies the chemical structure of the biodegradable polyester. US10087326B2 discloses the dispersion of the hydrolytically unstable polymer in an aqueous solution under the condition without volatile organic solvent. The process comprises the step of mixing polylactic acid, polyvinyl alcohol as the stabilizer, and water in the reactor or extruder at the temperature from 25 to 170 °C under pressure. Then, said mixture was mixed with xanthan gum to form the dispersion of the polylactic acid particle in water. However, said method requires a microparticle of polylactic acid as the precursor in the extruder at a temperature higher than the melting temperature of the polylactic acid to obtain the aqueousbased biodegradable polymer.

EP2069431B1 discloses the preparation process for starch nanoparticle preparing nanobiopolymer in large scale. This process comprises steps of: a) feeding biopolymer, plasticizer and water to a twin screw extruder having screw structure to provide shear force to the biopolymer, wherein the screw structure comprising at least two steam seals; upstream pressure and downstream mixer, and wherein the steam seal protected the steam from flowing back to the feeding zone, and the temperature in the reaction zone was higher than the water boiling point at atmosphere; and b) adding the crosslinking agent to the end of the feeding zone, wherein the melted biopolymer was pressed through the die. This method can prepare the nano-biopolymer in large scale. Nevertheless, this method requires twin screw extruder with specific screw structure.

W02022003195A1 discloses the coating composition prepared from aqueous dispersion biopolymer for coating on paper surfaces. The coating was prepared by melting polybutylene succinate at the temperature of 130 °C in a high-pressure reactor and stabilized by adding polyvinyl alcohol. Then, hot water was slowly added to the high-pressure reactor. In this method, the flow rate of hot water affected directly to the obtained particle size. The particle size of polybutylene succinate dispersed in the solution was about 6.9 pm. However, this method requires a pump for loading hot water to the high-pressure reactor under pressure and it is two steps process in which the polymer resin is melted and followed by the dispersing process of the biopolymer at high temperature.

From all above, this invention relates to the process for preparing an aqueous-based biodegradable polymer dispersions composition, wherein the process comprises the following steps: (a) mixing biopolymer, plasticizer, stabilizer, and aqueous solution in the stir tank reactor at the temperature from 90 to 150 °C and pressure from 3 to 5 bars until the biodegradable polymer composition becomes homogeneous;

(b) subjecting mixture in step (a) to reflux pressurization system to disperse said mixture into a small particle and reflux back to the stir tank reactor; and

(c) reducing the temperature of the stir tank reactor down to the temperature from 25 to 40 °C to obtain the stable aqueous-based biodegradable polymer dispersions composition.

The stable aqueous-based biodegradable polymer dispersions composition prepared from the process according to the invention can be stored for a long time, prepared in a large scale, and used as packaging coating into film layer substituted for the packaging coating from petroleum.

SUMMARY OF INVENTION

The present invention relates to the process for preparing an aqueous-based biodegradable polymer dispersions composition, comprises the following steps:

(a) mixing biopolymer, plasticizer, stabilizer, and aqueous solution in the stir tank reactor at the temperature from 90 to 150 °C and pressure from 3 to 5 bars until the biodegradable polymer composition becomes homogeneous;

DETAILED DESCRIPTION The present invention relates to the process for preparing an aqueous-based biodegradable polymer dispersions composition.

Any aspect demonstrated herein is meant to include the other application of this invention unless stated otherwise.

Technical terms or scientific terms used here have definitions by a person skilled in the art unless stated otherwise.

Any tools, equipment, methods, or chemicals named here mean tools, equipment, methods, or chemicals being used commonly by a person skilled in the art unless stated otherwise that they are tools, equipment, methods, or chemicals specific only to this invention.

Use of singular noun or singular pronoun with “comprising” in claims or specification means “one” and including “one or more”, “at least one”, and “one or more than one”.

All compositions and/or methods disclosed and claims in this application aim to cover embodiments from any action, performance, modification, or adjustment without any experiment that significantly different from this invention and obtain with object with utility and resulted as same as the present embodiment according to a person ordinary skilled in the art although without specifically stated in claims. Therefore, substitutable, or similar object to the present embodiment, including any little modification or adjustment that clearly seen by a person skilled in the art should be construed as remains in spirit, scope, and concept of invention as appeared in appended claims.

Throughout this application, term “about” means any number that appeared or showed here that could be varied or deviated from any error of equipment, method, or personal using said equipment or method.

Throughout this application, unit being used to calculate percentage throughout this application means % by weight unless being stated otherwise.

Reflux pressurization system means the device that generates the reflux pressure to give shear force. This includes by not limited to inline homogenizer pumps, high-shear mixer, or magnetic drive centrifugal pumps. Biopolymer according to this invention means including biobased polymer made from biomass or monomer obtained from biomass but not limited to amorphous biopolymers and/or semicrystalline biopolymers.

The Biodegradable polymer according to this invention means including a polymer that can be degraded by microorganisms to transform its chemical structure into biomass, water, and natural gas. Examples are polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polybutylene adipate-co-terephthalate.

Hereafter, invention embodiments are shown without any purpose to limit any scope of the invention.

(b) subjecting mixture in step (a) to reflux pressurization system to disperse said mixture into a small particle and reflux back into the stir tank reactor; and

In one aspect of the invention, the reflux pressurization system in step (b) is selected from inline homogenizer pumps, high-shear mixer, or magnetic drive centrifugal pumps.

In one aspect of the invention, the biopolymer according to this invention is selected from amorphous biopolymers and/or semicrystalline biopolymer.

In one aspect of the invention, the biopolymer is selected from polybutylene succinate, polybutylene succinate adipate, polycaprolactone, polybutylene adipate-co-terephthalate, or a mixture thereof.

In one aspect of the invention, the biopolymer is polybutylene succinate, polybutylene succinate adipate, or a mixture thereof. In one aspect of the invention, the plasticizer is selected from tributyl citrate, polyglyceryl alkylate, polyol ester, bio-based polymeric plasticizer, polyethylene glycol, triethyl citrate, acetyl tributyl citrate, dioctyl adipate, adipate, glycerol, or a mixture thereof. The plasticizer helps to reduce the internal binding of molecule and reduces viscosity and glass transition temperature (T_g) of the biodegradable polymer by obstructing the binding between polymer chains. Said plasticizer is selected from liquid plasticizer having a low molecular weight including plasticizer prepared from biochemical and biodegradable plasticizer.

In one aspect of the invention, the plasticizer is triethyl citrate, polyol ester, bio-based polymeric plasticizer, or a mixture thereof.

In one aspect of the invention, the stabilizer is selected from polyvinyl alcohol, fatty alcohol ethoxylate, ethylene oxide-propylene oxide block copolymers, polyethylene glycol, carboxymethyl cellulose, carboxymethyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose, methyl cellulose, or a mixture thereof.

In one aspect of the invention, the stabilizer is polyvinyl alcohol.

In one aspect of the invention, the precursor of the biodegradable polymer further comprises surfactant, wax, engineered polysaccharide, crosslinking agent, thickener, or a mixture thereof.

In one aspect of the invention, the biodegradable polymer composition further comprises the stabilizing agent for encapsulating the polymer particle to increase the stability of said particle in the dispersion in aqueous solution and to prevent the particles to coagulate and precipitate. In some cases, the stabilizing agent may form coating on the surface of the polymer particle. In some cases, the stabilizing agent may be referred to as a colloidal stabilizer.

In one aspect of the invention, the biodegradable polymer composition further comprises the surfactant for stabilizing the particle in water medium. Generally, the surfactant comprises hydrophilic and hydrophobic functional groups. During dispersing, these surfactants are the medium between biodegradable polyester particle and water medium by reducing surface force between phases to help the dispersion in water. The surfactant comprises a polysorbate (such as Tween), sorbitan derivatives (such as span), or a mixture thereof from 0.5 % by weight to about 1 % by weight of emulsion. In some aspects of the invention, the biopolymer composition according to the invention further comprises the crosslinking agent for improving water resistance property and preventing detachment of film during use.

In some aspects of the invention, the biopolymer composition according to the invention further comprises the crosslinking agent selected from dialdehyde, including by not limited to glutaraldehyde, glyoxal, carbonic acid potassium zirconium salt, or a mixture thereof.

In some aspects of the invention, the biopolymer composition according to the invention further comprises the crosslinking agent from 1 % by weight to 5 % by weight of the aqueous-based biodegradable polymer composition.

In one aspect of the invention, the aqueous-based biodegradable polymer dispersions composition comprises:

- biopolymer from 5 - 40 % by weight;

- plasticizer from 5 - 20 % by weight;

- stabilizer from 1 - 20 % by weight;

- surfactant from 0 - 20 % by weight; and

- aqueous solution from 30 - 70 % by weight; wherein the sum of biopolymer composition is 100 % by weight.

In some aspects of the invention, the aqueous-based biodegradable polymer dispersions composition comprising:

- biopolymer from 10 - 40 % by weight;

- plasticizer from 5 - 20 % by weight;

- stabilizer from 1 - 20 % by weight;

- surfactant from 0 - 5 % by weight; and

In some aspects of the invention, the aqueous-based biodegradable polymer dispersions prepared by the process according to the present invention has particle size smaller than 7 microns. In some aspects of the invention, the aqueous-based biodegradable polymer composition prepared from the invention process can be applied to but not limited to coated substrate, packaging film coating, adhesive, or a preparation of composite material.

The following examples are only for demonstrating one aspect of this invention, not for limiting the scope of this invention in any way.

Preparation of comparative sample 1

The preparation of the aqueous-based biodegradable polymer dispersions composition in stir tank reactor without reflux pressurization system can be done by mixing polybutylene succinate adipate in resin pellet (FD92PM, manufactured by PTTMCC), polyvinyl alcohol (POVAL™ 5-88, manufactured by Kuraray), and triethyl citrate (CITROFOL® Al, manufactured by Jungbunzlauer) as the plasticizer at the ratio of 1.00: 0.01-0.75: 0.25 - 0.50 % by weight of resin. Then, the surfactant (Tween 20, manufactured by CRODA) was added at the ratio of 0.05 - 1.00 % by weight and mixed with water in the stir tank reactor (RCle High Performance Thermostat, manufactured by METTLER TOLEDO) at the pressure of 3 to 5 bars. The mixture was heated at 90 to 130 °C. Then, the mixture was stirred in the reactor and cooled down to the temperature about 30 to 40 °C to obtain the aqueous-based biopolymer.

Preparation of comparative sample 2

The preparation of comparative sample 2 was performed by a polymer melting method and hot water droplets in stir tank reactor. Polybutylene succinate adipate (FD92PM, manufactured by PTTMCC), polyvinyl alcohol (POVAL™ 5-88, manufactured by Kuraray), and triethyl citrate (CITROFOL® Al, manufactured by Jungbunzlauer) are mixing at the ratio of 1.00: 0.01-0.75: 0.25 - 0.50 % by weight of resin. Then, the surfactant (Tween 20, manufactured by CRODA) was added at the ratio of 0.05 - 1.00 % by weight of the resin. All substances were heated at a temperature higher than resin melting temperature. After all components were melted at the shear rate of 800 rpm, and hot water was dropped into the reactor. The mixture was cooled downed to the temperature about 30 to 40 °C to obtain the aqueous-based biopolymer.

Preparation of sample according to the invention 1

The preparation of the biopolymer dispersion according to the invention can be done by the same method as described in comparative sample 1. Then the mixture was circulated in the stir tank reactor until melted, and the mixture was circulated from the reactor to the reflux pressurization system (pressure vessel, manufactured by JUCHHEIM Laborgerate GmbH and stainless-steel magnetic drive centrifugal pumps, manufactured by CP Pump Systems) and recirculated back to the reactor again until no polymer pellet left in the reactor. All mixtures are homogeneous, and then the end of the emulsification. Emulsion was cooled down to the temperature of 30 to 40 °C to avoid crystallization of the polymer or coagulation of the particles.

Preparation of sample according to the invention 2

The sample according to invention 2 can be prepared by the same preparation method as the sample according to the invention 1 but using polyol ester (Loxiol AF80, manufactured by Emery Oleochemicals LLC) as plasticizer.

Preparation of sample according to the invention 3

The sample according to invention 3 can be prepared by same preparation method as the sample according to the invention 1 but using biological polymer plasticizer (Edenol 2178, manufactured by Emery Oleochemicals LLC) as plasticizer.

Testing of the aqueous-based biodegradable polymer dispersions composition

Measurement of an average particle size using optical microscope

The measurement of an average particle size can be performed by dropping the solution onto the slide glass and measuring the particle size by the microscope (manufactured by Olympus, OLYMPUS BX51).

Dispersion results of the aqueous-based biodegradable polymer dispersions composition

From Table 1, it was found that the biopolymer prepared by methods according to comparative sample 1 and comparative sample 2 were not stable because they could not well dispersed in water. Moreover, they were coagulated and precipitated. The average particle sizes were about 40 to 50 pm and 20 to 40 pm, respectively. However, the average particle sizes of the biopolymer prepared according to the invention were about 4 to 7 pm. Also, said stable small particles prepared according to the invention were well dispersed in aqueous solution and could keep under room temperature for more than 3 months.

Table 1 shows testing of the aqueous-based biodegradable polymer prepared by comparative sample and sample according to the invention.

* Tested by leaving to precipitate at room temperature (about 25 to 35 °C), the unstable samples precipitated within 1 hour.

Testing of product coating using biopolymer composition according to comparative sample and sample according to the invention

The product coating method using biopolymer composition according to the sample in the present invention comprises the steps of; subjecting the aqueous-based biodegradable polymer composition to coat on paper packaging surface using 50 pm thick wire bar coater (manufactured by Alphani International Co., Ltd., brand name Biuged). Then, the solution was allowed to evaporate from the coating surface to form dried coating surface for about 1 to 2 mins. The dried substrate was heated at the temperature of 110 to 130 °C to form the biopolymer film.

Testing results of product coating using biopolymer composition according to comparative sample and sample according to the invention

From the results, when testing the product coated with the biopolymer composition according to comparative sample and sample according to the invention using scanning electron microscope, manufactured by Jeol USA Inc., JSM-6510LV), it was found that the product coated with the biopolymer composition according to comparative sample had rough surface, large particle, and there was void between coating layer and product surface. This caused detachment during use. On the other hand, the product coated by the biopolymer composition according to the sample according to the invention had a smooth surface without any void between coating layer and product surface. This made the film layer unlikely to be detached and it also protected moisture. In conclusion, the process for preparing an aqueous-based biodegradable polymer dispersions composition according to this invention provides the biodegradable polymer that is well dispersed in the aqueous solution. This process can be easily done on a large scale and provided the stable aqueous-based biodegradable polymer dispersions composition for more than three months. Moreover, when applied in product coating, it can form a good packaging coating film having a smooth surface of a thin layer film layer which is suitable for industrial applications.

PREFERRED EMBODIMENT OF THE INVENTION

The preferred embodiment of the invention is as provided in the description of the invention.

Claims

1. A process for preparing an aqueous-based biodegradable polymer dispersions composition comprises the following steps:

(a) mixing biopolymer, plasticizer, stabilizer, and aqueous solution in a stir tank reactor at the temperature from 90 to 150 °C and pressure from 3 to 5 bars until the biodegradable polymer composition becomes homogeneous;

(b) subjecting mixture in step (a) to reflux pressurization system to disperse said mixture into small particles and reflux back into the stir tank reactor; and

2. The process according to claim 1, wherein the reflux pressurization system in step (b) is selected from inline homogenizer pump, high shear mixer, or magnetic drive centrifugal pump.

3. The process according to claim 1, wherein the biopolymer is selected from polybutylene succinate, polybutylene succinate adipate, polycaprolactone, polybutylene adipate-co- terephthalate, or a mixture thereof.

4. The process according to claim 1, wherein the biopolymer is polybutylene succinate, polybutylene succinate adipate, or a mixture thereof.

5. The process according to claim 1, wherein the plasticizer is selected from tributyl citrate, polyglyceryl alkylate, polyol ester, bio-based polymeric plasticizer, polyethylene glycol, triethyl citrate, acetyl tributyl citrate, dioctyl adipate, adipate, glycerol, or a mixture thereof.

6. The process according to claim 1, wherein the plasticizer is triethyl citrate, polyol ester, bio-based polymeric plasticizer, or a mixture thereof.

7. The process according to claim 1, wherein the stabilizer is selected from polyvinyl alcohol, fatty alcohol ethoxylate, ethylene oxide-propylene oxide block copolymers, polyethylene glycol, carboxymethyl cellulose, carboxymethyl hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methylcellulose, methyl cellulose, or a mixture thereof.

8. The process according to claim 1, wherein the stabilizer is polyvinyl alcohol.

9. The process according to claim 1, wherein the precursor of the biodegradable polymer further comprises surfactant, wax, engineered polysaccharide, crosslinking agent, thickener, or a mixture thereof.

10. The process according to claim 1, wherein the aqueous-based biodegradable polymer dispersions composition comprising:

- biopolymer from 5 - 40 % by weight;

- plasticizer from 5 - 20 % by weight;

- stabilizer from 1 - 20 % by weight;

- surfactant from 0 - 20 % by weight; and

11. The process according to claim 1, wherein the aqueous-based biodegradable polymer dispersions composition comprising:

- biopolymer from 10 - 40 % by weight;

- plasticizer from 5 - 20 % by weight;

- stabilizer from 1 - 20 % by weight;

- surfactant from 0 - 5 % by weight; and

12. The aqueous-based biodegradable polymer dispersions prepared from any one of the preceding claims, wherein the particle size of the biodegradable polymer is lower than 7 microns.

13. A coated substrate comprising film formed by the aqueous-based biodegradable polymer dispersions composition prepared from any one of the preceding claims.