Hydrolysis-resistant polyester-containing composition

Abstract

The present invention relates to a compound of formula (I) 1 , R 2 , R 4 and R 6 = ethyl, R 3 , R 5 and n is each independently C1-C6-alkyl), and the present invention relates to hydrolytically stabilized polyethylene terephthalate (PET)- and / or polylactic acid (PLA)-containing compositions comprising monomeric carbodiimides, as well as methods for preparing and using these carbodiimides. JPEG2025534772000014.jpg33170

Description

[Technical Field]

[0001] The present invention relates to hydrolytically stabilized polyester-containing compositions (hydrolytically stabilized polyester-containing compositions), such as compositions comprising polyethylene terephthalate (PET) and compositions comprising polylactic acid (PLA), their production methods, and their uses. [Background technology]

[0002] PET is used for fibers, for moulding compounds for producing plastic products such as drinks bottles, and for the production of films, for example for electrical insulation and solar cells.

[0003] The water content of PET typically supplied by manufacturers in granular form for further processing is on the order of 0.2-0.4% (2000-4000 ppm); the water content and its distribution on the surface and within the granules depend on the crystallinity of the PET in the granules and their composition.

[0004] Because the "natural" moisture content of commercially available PET granules causes hydrolytic degradation of PET during the production of PET melts, which affects the quality of the resulting final product, the manufacturing procedure for high-quality PET products typically involves crystallizing the moist PET granules obtained from the manufacturer by heating them and then thoroughly drying them. In particular, when biaxially oriented PET films are used as capacitor films, films for magnetic recording media, X-ray film substrates, or for graphic arts applications, films with excellent optical and mechanical properties, along with high surface quality and high uniformity, are required. To achieve these properties, maximum efficiency in limiting hydrolytic degradation during processing is necessary.

[0005] PET is particularly susceptible to hydrolysis when melted at high temperatures. In contrast, final products made from solid PET after solidification show little significant reactivity to moisture. However, to prevent degradation of fiber quality during the service life of fabrics made from it, PET typically contains hydrolysis stabilizers, typically polymers containing carbodiimide groups, as additives. Polycarbodiimide compounds are present in the final PET fiber in a uniform dispersion in an amount of approximately 1-2.5% by weight to bind trace amounts of water that can penetrate the fiber and cause partial hydrolysis of the PET, gradually degrading its quality. These hydrolysis stabilizers alone serve to improve the long-term stability of the final PET product.

[0006] However, polymeric carbodiimides have disadvantages compared to monomeric carbodiimides, since they are less reactive at relatively low temperatures, are difficult to disperse in polymer matrices, and require the use of specialized technical equipment under relatively severe process conditions.

[0007] Second, some monomeric carbodiimides, such as 2,6-bis(diisopropylcarbodiimide), have the drawback of being toxic or insufficiently effective. Further monomeric aromatic carbodiimides with large steric hindrance are very effective in PET, but must first be purified by additional, complex and expensive downstream purification processes, such as recrystallization or multiple distillations, as described, for example, in U.S. Pat. No. 5,629,493. Monomeric carbodiimides with smaller steric hindrance, as described in U.S. Pat. No. 5,629,493, are very reactive as acid scavengers in polyester polyols, but exhibit poor long-term hydrolytic stabilization in PET.

[0008] Furthermore, in most biobased aliphatic polyesters, such as polylactic acid (polylactide, PLA), by contrast, most monomeric carbodiimides by themselves are poorly effective. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] European Patent No. 3686240 [Patent Document 2] Chinese Patent Application Publication No. 108912014 Summary of the Invention [Problem to be solved by the invention]

[0010] One of the objects of the present invention was therefore to provide improved hydrolysis-stabilized PET and PLA compositions that do not have the above-mentioned drawbacks, i.e. that show very good protection against hydrolysis, are easy and cheap to produce, and are non-toxic. [Means for solving the problem]

[0011] Surprisingly, this object is achieved by combining polyethylene terephthalate (PET) and / or polylactic acid (PLA) with a polymer of the following formula (I): [ka] (In the formula, R 1 , R 2 , R 4 , and R 6 is ethyl, and R 3 , R 5 are each independently C1-C6-alkyl. and at least one monomeric carbodiimide of the formula:

[0012] The C1-C6-alkyl groups of the carbodiimides of formula (I) used may be linear and / or branched.

[0013] In one preferred embodiment, R 3 and R 5 is independently selected from t-butyl, i-propyl, and methyl.

[0014] In one particularly preferred embodiment, R 3 and R 5 are each methyl, that is, the carbodiimide has the following formula (II): [ka] Matches.

[0015] The present invention further provides the use of a monomeric carbodiimide of formula (I) above for the hydrolytic stabilization of PLA and / or PET.

[0016] The carbodiimide used in the present invention preferably has an NCN content of 8% to 13% by mass, preferably 11% to 13% by mass.

[0017] The carbodiimide used in the present invention is a carbodiimide represented by the following formulas (III) and (IV): [ka] and [ka] (In the formula, R 1 , R 2 , R 4 , and R 6 is ethyl, R 3 , R 5 are each independently C1-C6-alkyl, preferably t-butyl, i-propyl or methyl, and most preferably methyl. can be preferably prepared by carbodiimidation of a trisubstituted benzene isocyanate of the formula:

[0018] One preferred trisubstituted benzeneisocyanate used is 2,6-diethyl-4-methylphenyl isocyanate. The trisubstituted benzeneamines required for the preparation of the above compounds can be prepared by Friedel-Crafts alkylation of aniline with the appropriate alkene, haloalkane, haloalkenebenzene, and / or halocycloalkane, as is well known to those skilled in the art.

[0019] These compounds are then reacted with phosgene to give the corresponding trisubstituted benzene isocyanates.

[0020] Carbodiimidization is preferably carried out by the method described in Angew. Chem. 93, pp. 855-866 (1981), or in DE-A-11 30 594, or in Tetrahedron Letters 48 (2007), pp. 6002-6004.

[0021] In a preferred embodiment of the present invention, the catalyst used in the preparation of the compound of formula (I) is a strong base or a phosphorus compound. It is preferred to use phospholene oxide, phospholidine, or phospholine oxide, and the corresponding sulfide. Additional catalysts that can be used include tertiary amines, basic metal compounds, alkali metal and alkaline earth metal oxides, hydroxides, alkoxides, or phenoxides, metal carboxylates, and non-basic organometallic compounds.

[0022] The carbodiimidization can be carried out either neat (ie, without solvent) or in a solvent.

[0023] The carbodiimides used in the process according to the invention can also be prepared by reacting the corresponding trisubstituted anilines with CS2 to give thiourea derivatives which are then converted to the carbodiimides in basic hypochlorite solution, or similarly by the method described in EP 0 597 382 A.

[0024] The crude product is preferably purified by distillation.In a further preferred embodiment, extraction with a solvent can be carried out before or after, preferably after, the distillation of carbodiimide.The suitable solvent used is preferably alcohol, ketone, nitrile, ether, ester, or a mixture of these substances.Aliphatic monoalcohols, such as alcohols from the group of methanol, ethanol, or isopropanol, are particularly preferred, and methanol is the most preferred.

[0025] In extraction, the carbodiimide is typically first stirred in at least one solvent, preferably at a temperature of 40-80°C, more preferably 50-60°C. While stirring, the mixture is then cooled, preferably to 10-25°C, more preferably 15-20°C. Two liquid phases are subsequently removed. Residual solvent is then removed from the carbodiimide in a stirred tank, preferably by distillation at 50-100°C, and the carbodiimide is delivered in liquid form.

[0026] In a further embodiment, in addition to distillation, recrystallization is carried out after distillation. Suitable solvents used for recrystallization are preferably alcohols, more preferably mixtures of these substances. Particularly preferred are aliphatic monoalcohols, such as alcohols from the group of methanol, ethanol, or isopropanol.

[0027] The compositions according to the invention are prepared by mixing PET and / or PLA with the monomeric carbodiimide of formula (I), preferably by means of a solids metering and mixing unit.

[0028] Solids metering and mixing units in the context of the present invention are single, twin and multi-screw extruders, continuous co-kneaders (Buss type) and batch kneaders, for example Banbury type, and other equipment conventionally used in the polymer industry.

[0029] The concentration of the carbodiimide of formula (I), based on the total amount of PET and / or PLA in the composition according to the invention or in the use according to the invention, is typically 0.5 to 5% by weight, preferably 0.7 to 2% by weight, more preferably 1.0 to 1.5% by weight.

[0030] In the context of the present invention, PET is any polyethylene terephthalate derived from terephthalic acid (or its reactive derivatives) and an alkanediol based on ethylene glycol. These also include modified polyethylene terephthalates (copolymers).

[0031] Preferred polyethylene terephthalates contain at least 80 mole %, preferably at least 90 mole %, of terephthalic acid residues, based on the dicarboxylic acid component, and at least 80 mole %, preferably at least 90 mole %, of ethylene glycol residues, based on the diol component.

[0032] Preferred polyethylene terephthalates also include copolyesters made from at least two acid components and / or at least two alcohol components, with a particularly preferred copolyester being poly(ethylene glycol / butane-1,4-diol) terephthalate.

[0033] Particularly preferred are polyethylene terephthalate, which is produced solely from terephthalic acid and its reactive derivatives, such as its dialkyl esters, and ethylene glycol. Polylactic acid preferably comprises an aliphatic polyester resin, the monomer of which is obtained by fermentation of starch, sugar, or carbohydrate. Polylactic acid is commercially available, for example, from NatureWorks or TotalEnergies Corbion, and can be produced by methods well known to those skilled in the art, such as ring-opening polymerization of lactide. Preparation of polylactic acid by ring-opening polymerization of lactide is not limited to either of the two enantiomers, L-lactic acid or D-lactic acid, or a mixture thereof. Polymers of L-lactic acid and / or D-lactic acid can be used in the context of the present invention.

[0034] With regard to the production of compositions composed of PET and / or polylactic acid (PLA) and of monomeric carbodiimides of formula (I) in a solids metering and mixing unit, reference is made to the previous statements.

[0035] The present invention further provides the use of the compositions according to the invention for the production of moldings, in particular for the production of mono- and multifilaments, fibers, injection moldings, and films.

[0036] The present invention further comprises moulded bodies, in particular mono- and multifilaments, fibres, injection mouldings and films, which comprise the composition according to the invention or which are obtainable by use of the composition according to the invention.

[0037] The scope of the present invention includes all above and below radical definitions, indices, parameters and explanations, whether of a general nature or mentioned within preferred ranges, in all combinations with one another, i.e. between the respective ranges and preferred ranges.

[0038] The following examples serve to illustrate the invention and do not have any limiting effect. [Example]

[0039] 1) Stabilizer A: Monomeric carbodiimide having an NCN content of about 10.8% by weight, based on 2,6-diisopropylphenyl isocyanate, available under the name Stabaxol® I from Lanxess Deutschland GmbH. 2) Stabilizer B: Formula [ka] (In the formula, R 1 , R 2 , R 4 , R 3 , R 5 , and R 6 is isopropyl) A monomeric carbodiimide based on 2,4,6-triisopropylphenyl isocyanate, having an NCN content of about 8.7% by mass, which is consistent with 3) Stabilizer C: A monomeric carbodiimide based on 2,6-diethylphenyl isocyanate, having an NCN content of about 13% by mass 4) Stabilizer D: A monomeric carbodiimide based on 2,6-diethyl-4-methylphenyl isocyanate, having an NCN content of about 12% by mass, which is consistent with formula (II) 5) PET available from Novapet S.A: Having an intrinsic viscosity of about 0.6. 6) PLA (Luminy 130) available from TotalEnergies Corbion 7) TPU (Desmopan) available from Covestro Deutschland AG

[0040] <Manufacture of Stabilizers A, B, C, and D Used> 400 g of isocyanate was charged into a 500 ml flanged flask heated and dried and filled with nitrogen under a nitrogen stream and heated to 140 °C. 400 mg of 1-methylphospholene oxide was added, and then the reaction mixture was heated to 160 °C within 5 hours. Next, the reaction was continued at 160 °C until an NCO content < 1% (corresponding to a conversion rate of > 95%) was achieved. The crude product thus obtained was purified as follows: a) Stabilizers A, C, and D are by distillation. b) Stabilizer B is additionally by recrystallization in a methanol / ethanol mixture (1:1).

[0041] <Hydrolytic Stabilization in PET> Before the tests described below, the hydrolysis stabilization effect in PET was evaluated by dispersing the stabilizers used (Stabilizers A, B, C, and D) at a concentration of 1.5% by mass in PET using a Werner & Pfleiderer ZSK 25 laboratory twin-screw extruder. F3 standard test pieces for measuring the ultimate tensile strength were prepared from the obtained granules in an Arburg Allrounder 320 S 150 - 500 injection molding machine.

[0042] For the hydrolysis test, these F3 standard test pieces were stored in water at a temperature of 90 °C, and their relative ultimate tensile strength was measured in units of %. For most applications, a relative ultimate tensile strength of more than 70% is required.

[0043] Table 1 shows the relative tensile strength as a percentage value starting at 100% on day 0.

[0044]

Table 1

[0045] Compared with the monomeric carbodiimides (Stabilizer A, Stabilizer B, and Stabilizer C) described in the prior art, the above results show that Stabilizer D of the present invention exhibits improved hydrolysis stability at the same usage amount.

[0046] <Hydrolysis Stabilization in PLA> Before the tests described below, the hydrolysis stabilization effect in PLA was evaluated by dispersing the stabilizers used (Stabilizers A and D) at a concentration of 1% by mass in PLA (Luminy L150 from TotalEnergies Corbion) using a Werner & Pfleiderer ZSK 25 laboratory twin-screw extruder. F3 standard test pieces for measuring the ultimate tensile strength were prepared from the obtained granules in an Arburg Allrounder 320 S 150 - 500 injection molding machine.

[0047] For the hydrolysis test, these F3 standard test pieces were stored in water at a temperature of 65 °C, and their relative ultimate tensile strength was measured in units of %.

[0048] Table 2 shows the relative tensile strength as a percentage value starting at 100% on day 0.

[0049]

Table 2

[0050] The above results show that compared with the monomeric carbodiimide (Stabilizer A) described in the prior art, Stabilizer D of the present invention exhibits improved hydrolysis stability at the same usage amount.

[0051] <Hydrolysis Stabilization in TPU> Prior to the tests described below, the hydrolysis stabilization effect of thermoplastic polyurethane elastomer (TPU) was evaluated by dispersing the stabilizers used (Stabilizers A, B, and D) in TPU (Desmopan 2587A from Covestro Deutschland AG) at a concentration of 1.5% by mass using a Werner & Pfleiderer ZSK 25 laboratory twin-screw extruder. Next, 70% F3 standard test pieces for measuring the ultimate tensile strength were prepared from the obtained granules in an Arburg Allrounder 320 S 150 - 500 injection molding machine.

[0052] For the hydrolysis test, these 70% F3 standard test pieces were stored in water at a temperature of 90 °C, and their relative ultimate tensile strength was measured in units of %.

[0053]

Table 3

[0054] The above results show that, compared to the monomeric carbodiimides described in the prior art (Stabilizers A and B), Stabilizer D exhibits poor hydrolytic stability in TPU compounds at the same dosage.

Claims

1. Polyethylene terephthalate (PET) and / or polylactic acid (PLA) and a polymer having the following formula (I): 【Chemical 1】 (In the formula, R １ , R ２ , R ４ , and R ６ is ethyl, R ３ , R ５ are each independently C １ -C ６ -alkyl) and at least one monomeric carbodiimide of the formula:

2. R ３ and R ５ 2. The composition of claim 1, wherein is t-butyl, i-propyl, or methyl.

3. R ３ and R ５ 2. The composition of claim 1, wherein is methyl.

4. 4. Composition according to any one of claims 1 to 3, characterized in that the proportion of carbodiimide of formula (I) is 0.5 to 5% by weight, preferably 0.7 to 2% by weight, more preferably 1.0 to 1.5% by weight, based on the total amount of PET and / or PLA.

5. 5. A process for producing a composition according to any one of claims 1 to 4, characterized in that PET and / or PLA are mixed with said at least one monomeric carbodiimide of formula (I) by means of a solids metering and mixing unit.

6. In the preceding step, in the presence of a catalyst and optionally a solvent, at a temperature between 40° C. and 200° C., with elimination of carbon dioxide, compounds of the following formulae (III) and (IV): 【Chemistry 2】 and 【Chemistry 3】 (In the formula, R １ ~R ６ has the definition according to any one of claims 1 to 3) 6. The method according to claim 5, wherein the carbodiimide of formula (I) is prepared by carbodiimidation of a trisubstituted benzene isocyanate of the formula (I) followed by purification by distillation and / or extraction.

7. 7. The method of claim 6, wherein the carbodiimide of formula (I) is purified by distillation followed by extraction.

8. The following formula (I): 【Chemistry 4】 (In the formula, R １ , R ２ , R ４ , and R ６ is ethyl, and R ３ , R ５ are each independently C １ -C ６ -alkyl, preferably t-butyl, i-propyl, or methyl, more preferably methyl) Use of the monomeric carbodiimides of formula (I) for the hydrolytic stabilization of PLA and / or PET.

9. R ３ and R ５ The use according to claim 8, characterized in that is t-butyl, i-propyl, or methyl.

10. R ３ and R ５ The use according to claim 8, characterized in that is methyl.

11. 11. Use according to any one of claims 8 to 10, characterized in that 0.5 to 5% by weight, preferably 0.7 to 2% by weight, more preferably 1.0 to 1.5% by weight of said monomeric carbodiimide of formula (I), based on the total amount of PET and / or PLA, is used.

12. Use of the composition according to any one of claims 1 to 3 for the production of moulded bodies, in particular for the production of mono- and multifilaments, fibres, injection moulded bodies and films.

13. Molded bodies, in particular mono- and multifilaments, fibers, injection moldings and films, comprising a composition according to any one of claims 1 to 4.

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