US-20260125554-A1 - THERMOPLASTIC POLYMER BLEND AND USE THEREOF

US20260125554A1US 20260125554 A1US20260125554 A1US 20260125554A1US-20260125554-A1

Abstract

The present invention relates to a thermoplastic polymer blend comprising (g) at least one thermoplastic, hydrophobically modified starch as component (a), (h) at least one thermoplastic native starch as component (b), and (i) at least one thermoplastic polyester as component (c), which selected from the group consisting of aliphatic polyesters, aliphatic-aromatic polyesters and mixtures thereof. The invention also relates to a process for preparing such a thermoplastic polymer blend, and a mono-layered or multi-layered film comprising at least one layer made of a thermoplastic polymer blend.

Inventors

Robert Loos
Norbert Effen
Carsten Sinkel
Joerg AUFFERMANN
Nora SCHLUTT

Assignees

BASF SE

Dates

Publication Date: 20260507
Application Date: 20231004
Priority Date: 20221006

Claims (17)

1 .- 16 . (canceled)
17 . A thermoplastic polymer blend, comprising (a) at least one thermoplastic, hydrophobically modified starch as component (a), (b) at least one thermoplastic native starch as component (b), and (c) at least one thermoplastic polyester as component (c), which is selected from the group consisting of aliphatic polyesters, aliphatic-aromatic polyesters and mixtures thereof.
18 . The blend according to claim 17 , comprising the components (a) and (b) in the following relative amounts, based on the total weight of components (a) and (b), where the amounts of the components (a) and (b) are calculated in their anhydrous form: (a) 1 to 70% by weight of the component (a), and (b) 30 to 99% by weight by weight of the component (b).
19 . The blend according to claim 17 , comprising the component (a) in an amount of 0.1 to 35% by weight, based on the total weight of the blend in anhydrous form, where the amount of (a) is calculated as the anhydrous form of component (a).
20 . The blend according to claim 17 , wherein component (a) is selected from the group consisting of thermoplastic starches hydrophobically modified with epoxides of the group of arylglycidyl ethers, alkyl substituted arylglycidyl ethers, arylglycidyl esters, alkyl substituted arylglycidyl esters, alkylglycidyl ethers and alkylglycidyl esters, and combinations thereof; thermoplastic starches hydrophobically modified with epoxidized vegetable oils; thermoplastic starches hydrophobically modified with fatty acids or ester forming derivatives thereof; thermoplastic starches hydrophobically modified with silanes; thermoplastic starches hydrophobically modified with alkyl-substituted anhydrides of dicarboxylic acids; thermoplastic starches hydrophobically modified with isocyanates; and mixtures thereof.
21 . The blend according to claim 20 , wherein component (a) is selected from the group consisting of thermoplastic starches hydrophobically modified with epoxidized vegetable oils and mixtures thereof.
22 . The blend according to claim 17 , wherein component (a) comprises one or more plasticizer selected from polyols.
23 . The blend according to claim 17 , comprising 5 to 70% by weight based on the total weight of blend in anhydrous form, of a combination of at least one thermoplastic, hydrophobically modified starch (a) and at least one native starch (b), where the amounts of the components (a) and (b) are calculated in their anhydrous form; and 30 to 95% by weight based on the total weight of blend in anhydrous form, of at least one polyester (c).
24 . The blend according to claim 17 , comprising 2 to 30% by weight based on the total weight of blend in anhydrous form, of at least one thermoplastic, hydrophobically modified starch (a); 5 to 63% by weight based on the total weight of blend in anhydrous form, of at least one thermoplastic native starch (b); and 35 to 93% by weight based on the total weight of blend in anhydrous form, of at least one polyester (c).
25 . The blend according to claim 17 , wherein the component (c) is biodegradable.
26 . The blend according to claim 17 , wherein component (c) comprises a combination of at least one aliphatic-aromatic polyester (c1) and at least one aliphatic polyester (c2).
27 . The blend according to claim 26 , wherein aliphatic polyester (c2) is selected from the group consisting of polyhydroxyalkanoates and polylactic acids, and mixtures thereof.
28 . The blend according to claim 17 , wherein component (c) comprises an aliphatic-aromatic polyester (c1) selected from the group of aliphatic-aromatic polyesters comprising: c1-i) from 25 to 70 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii, of repeating units c1-i of at least one aliphatic C 4 -C 18 -dicarboxylic acid; c1-ii) from 30 to 75 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii, of repeating units c1-ii of terephthalic acid; and c1-iii) from 98 to 102 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii, of repeating units c1-iii of at least one C 2 -C 6 -alkandiol; and aliphatic-aromatic polyesters comprising: c2-i) from 20 to 60 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii′, of repeating units c1-i of at least one aliphatic C 4 -C 18 -dicarboxylic acid; c2-ii) from 40 to 80 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii′, of repeating units c1-ii′ of furandicarboxylic acid; and c2-iii) from 98 to 100 102 mol % based on the total of the molar percentages of repeating units c1-i and c1-ii′, of repeating units c1-iii of at least one C 2 -C 6 -alkandiol.
29 . The blend according to claim 17 , wherein the component (c) comprises an aliphatic-aromatic polyester (c1) which is selected from the group consisting of poly(butylene adipate-co-terephthalate), poly(butylene azelate-co-terephthalate), poly(butylene sebacate-co-terephthalate), poly(butylene sebacate-co-adipate-co-terephthalate), poly(butylene sebacate-co-succinate-co-terephthalate), poly(butylene azelate-co-adipate-co-terephthalate), poly(butylene azelate-co-succinate-co-terephthalate), poly(butylene adipate-co-furanoate) and poly(butylene sebacate-co-furanoate), poly(butylene azelate-co-furanoate), and mixtures thereof.
30 . A process for preparing a thermoplastic blend according to claim 17 , comprising the steps: (i) providing at least one component (a) or a combination of a hydrophobically modified starch and one or more plasticizer, which is converted at step (iv) into the thermoplastic, hydrophobically modified starch (a); (ii) providing at least one thermoplastic native starch (b) or a combination of a native starch and one or more plasticizer, which is converted at step (iv) into the thermoplastic native starch (b); (iii) providing at least one polyester (c); (iv) optionally providing one or more further components other than components (a), (b) and (c); and (v) introducing and mixing of the components provided at steps (i) to (iii) and optionally (iv).
31 . The process according to claim 30 , wherein step (v) is carried out in an extruder.
32 . A mono-layered or multi-layered film comprising at least one layer made of a blend according to claim 17 .

Description

The present invention relates to a thermoplastic polymer blend comprising a thermoplastic polyester of the group of aliphatic polyesters and aliphatic-aromatic polyesters and a thermoplastic starch. The invention also relates to a process for preparing such a thermoplastic polymer blend, and a mono-layered or multi-layered film comprising at least one layer made of a thermoplastic polymer blend. BACKGROUND ON THE INVENTION The use of thermoplastic materials such as polystyrene, polyethylene and polyurethane has long been established in many technical areas. However, these conventional thermoplastic materials face an increasing criticism for environmental reasons. Starch is an important natural polymer that is increasingly being considered as an alternative to conventional plastics due to its biodegradability and other favourable properties for the environment as well as its good availability. With water and plasticisers such as glycerol, starch can be processed into so-called “thermoplastic starch (TPS)” using conventional polymer processing techniques such as extrusion, injection molding and compression molding. However, materials based on native starch often have poor processibility, mechanical properties and stability. Therefore, modified starches, e.g. hydroxypropyl starch, are used instead of native starch. It is also known to blend native starch with other biodegradable polymers, such as polycaprolactone. Such blends are commercially available, e.g. PLANTIC™ HP and Mater-Bi®. Thermoplastic starches have been known for many years and various processes for their production are described in the literature, for example in U.S. Pat. No. 5,362,777, WO 99/61524, DE 198 24 968 A1, WO 2012/162085 A1 or WO 2006/042364 A1. Thermoplastic starches are prepared from starches by plastifying the starch with a suitable plasticiser, which is typically a polyol. However, despite the addition of plasticisers, TPS is inherently brittle and hydrophilic. When using TPS, the high demands placed on technical products such as mechanical strength and water resistance, especially in film extrusion, are difficult to be met. When blending TPS with other thermoplastic polymers, such as polyesters, one faces the problem that the TPS has a very high melt viscosity, whereas the other polymer tends to have a significantly lower melt viscosity. Due to this difference in melt viscosities, a fine dispersion of TPS in a polymer matrix is difficult to achieve and requires efficient blending under high shear. This may lead to mechanical damage of the TPS phase. In addition, the high melt viscosity of the TPS makes processing more difficult, which is reflected in increased torque and pressure conditions in the extruder. In addition, the compatibility of the hydrophilic TPS and the hydrophobic polymer is limited. This leads to an impairment of the mechanical material properties such as low tensile strength and elongation, as well as to impairments in the appearance of the end product, which in part manifest themselves in reduced transparency and increased opacity. Various publications deal with the above mentioned problems of the starch blend containing TPS, e.g. the problem of opacity when blending TPS with other biopolymer compounds. WO2022/157380 describes polymer compositions containing 25.5% by weight of a native starch comprising pea starch and 30 to 74.5% by weight of a thermoplastic aliphatic-aromatic Copolyester. The mechanical properties of the blends are not satisfactory. CN112724472 discloses polymer blends with high starch content containing starch, a starch modifier, a compatibilizer, a plasticizer, a starch modifier and inorganic fillers. The mechanical properties of the blends are not satisfactory. WO2019138022A1 and WO2020136231A1 describe the production of a hydrophobically modified thermoplastic starch comprising the extrusion of a mixture of a native starch, a polylol, for example sorbitol, an epoxide selected from the group of epoxidized plant oils, and a carboxylic acid, such as citric acid. Also mentioned are blends of the thus obtained hydrophobically modified TPS with conventional polymers such as aliphatic-aromatic polyesters, e.g. poly(butylene adipate-co-terephthalate) (PBAT). The thus obtained blends contain a high amount of the hydrophobically modified starch and thus are quite expensive. SUMMARY OF THE INVENTION Yet, there is still the need to overcome the above-mentioned disadvantages and to improve the properties, especially the mechanical properties of the thermoplastic polymer blends based on combinations of aliphatic or aliphatic-aromatic polyesters and TPS and of the products based thereon. At the same time, the polymer blend should be easily processible into thermoplastic polymer compounds and thermoplastic polymer films, especially in extrusion processing and blown or flat film extrusion Accordingly, the aim of the present invention is to provide thermoplastic polymer blends based on combinations of aliph