Search

DE-102021002539-B4 - Method for producing a flame-retardant polyester

DE102021002539B4DE 102021002539 B4DE102021002539 B4DE 102021002539B4DE-102021002539-B4

Abstract

Method for producing a flame-retardant polyester, comprising the following steps: - Reaction of a chain-forming monomer (A) with a phosphorus-containing polyester (B) and at least a difunctional alcohol (C) to form a reaction mixture, wherein the reaction is carried out at a temperature at which alcoholysis of the phosphorus-containing polyester (B) takes place, wherein the phosphorus-containing polyester (B) is obtainable by polycondensation of phosphorus-containing monomers (B1) with ester-forming monomers (B2), wherein the phosphorus-containing monomer (B1) is selected from the addition products of 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO) and core-substituted DOPO derivatives to unsaturated compounds from the group of mono- and polyvalent carboxylic acids and their anhydrides, and the ester-forming monomer (B2) is selected from the group consisting of mono- and polyhydric alcohols, mono- and polyhydric carboxylic acids and mixtures thereof, and - Producing a flame-retardant polyester from the reaction mixture, wherein the flame-retardant polyester comprises units of the chain-forming monomer (A), the phosphorus-containing polyester (B) and the at least difunctional alcohol (C).

Inventors

  • Michael Kraus
  • Alexander Hahn

Assignees

  • SCHILL + SEILACHER GMBH

Dates

Publication Date
20260513
Application Date
20210514

Claims (9)

  1. A process for producing a flame-retardant polyester, comprising the following steps: - Reacting a chain-forming monomer (A) with a phosphorus-containing polyester (B) and at least a difunctional alcohol (C) to form a reaction mixture, wherein the reaction is carried out at a temperature at which alcoholysis of the phosphorus-containing polyester (B) occurs, whereby the phosphorus-containing polyester (B) is obtainable by polycondensation of phosphorus-containing monomers (B1) with ester-forming monomers (B2), whereby the phosphorus-containing monomer (B1) is selected from the addition products of 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO) and core-substituted DOPO derivatives to unsaturated compounds from the group of mono- and polyhydric carboxylic acids and their anhydrides, and the ester-forming monomer (B2) is selected from the mono- and is selected from the group consisting of polyhydric alcohols, mono- and polyhydric carboxylic acids and mixtures thereof, and - producing a flame-retardant polyester from the reaction mixture, wherein the flame-retardant polyester comprises units of the chain-forming monomer (A), the phosphorus-containing polyester (B) and the at least difunctional alcohol (C).
  2. Procedure according to Claim 1 , characterized in that the chain-forming monomer (A) is selected from the group consisting of at least difunctional carboxylic acids, their diesters of monoalcohols and combinations thereof.
  3. Procedure according to Claim 2 , characterized in that the chain-forming monomer (A) is terephthalic acid, isophthalic acid, phthalic acid, 2,6-napthalendicarboxylic acid, adipic acid, 1,4-butanedioic acid and/or their dimethyl esters.
  4. Method according to one of the preceding claims, characterized in that the phosphorus-containing polyester (B) is used in a proportion of 1 to 20 percent by weight, based on the total mass of the reaction mixture.
  5. Method according to one of the preceding claims, characterized in that the at least difunctional alcohol (C) is an aliphatic diol.
  6. Method according to one of the preceding claims, characterized in that the at least difunctional alcohol (C) corresponds to the ester-forming monomer (B2).
  7. Method according to one of the preceding claims, characterized in that the molar ratio of at least difunctional alcohol (C) to phosphorus-containing polyesters (B) is 1:1 or higher.
  8. Method according to one of the preceding claims, characterized in that a reaction accelerator (D) is additionally used in the reaction mixture, wherein the reaction accelerator (D) is at least a difunctional ester.
  9. Method according to one of the preceding claims, characterized in that the conversion to the reaction mixture is carried out at a temperature of 150 °C or higher.

Description

The invention relates to a method for producing a flame-retardant polyester. Flame-retardant thermoplastic polymers can be obtained by adding non-reactive flame retardants, which can be incorporated into a base polymer through simple physical mixing or dissolution. In contrast, the production of flame-retardant thermoplastic polymers with reactive flame retardants—that is, thermoplastic polymers in which the flame retardant is incorporated into the base polymer—always requires at least one or more chemical process steps, which are generally carried out during the production of the base polymer. Non-reactive flame retardants allow for a so-called "late addition" process, in which the flame retardant is added to the base polymer shortly before processing, usually during an extrusion process, for example as a masterbatch. In contrast, such a process is normally not possible when using reactive flame retardants, as these undergo a chemical reaction with the base polymer and, under the temperature and pressure conditions prevailing during extrusion, in most cases cause polymer degradation. For the production of flame-retardant polyamides, a number of non-reactive, halogen-free flame retardants have long been used in technical applications. These offer advantages over halogenated flame retardants in terms of both process engineering and human and ecotoxicological safety. The DE 26 46 218 A1 Disclosure reveals phosphorus-containing flame retardants obtained by adding 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO) to an unsaturated compound having at least one ester-forming functional group and further reacting it with an ester-forming compound selected from dicarboxylic acids or ester-forming derivatives thereof, diols or ester-forming derivatives thereof, and oxycarboxylic acids or ester-forming derivatives thereof. These reactive, phosphorus-containing flame retardants are then reacted with dicarboxylic acids such as terephthalic acid and a glycol to form flame-resistant polyesters. The CN 104419003 A describes the use of a DOPO-based flame retardant for polyamides, whereby the flame retardant in this case is bound to the polymer chain by a graft copolymerization. From the DE 28 16 100 C2 Flame retardants are known which were obtained by polycondensation of the addition product of DOPO or DOPO derivatives to itaconic acid with polyhydric alcohols and have a molecular weight of 1,000 to 20,000 g/mol and a phosphorus content of 5.3 to 8.5 wt.%. The DE 10 2011 116 178 A1 This describes a flame retardant that is preferably used for the flame-resistant treatment of thermoplastics and thermosets. It is obtained by reacting a phosphinic acid derivative from the group of DOPO and core-substituted DOPO derivatives with an optionally substituted polydiene containing isolated C-C double bonds. From the EP 2 284 208 A1 A DOPO-based flame retardant is known that is suitable for the flame-retardant treatment of curable synthetic resins. It is generated from DOPO or core-substituted DOPO derivatives through several reaction steps involving the introduction of reactive functional groups. Also suitable as a flame retardant for curable synthetic resins is an addition product obtained by reacting DOPO and core-substituted DOPO derivatives with unsaturated compounds, as described in the DE 10 2008 009 298 A1 described. CN 111777641 A discloses the synthesis of a bifunctional DOPO derivative and its use as a flame retardant for epoxy resins. WO 2016/008074 A1 describes the use of a bifunctional DOPO derivative, which is used as a melt additive to impart flame-retardant properties to semi-aromatic polyamide or a mixture of semi-aromatic and aliphatic polyamide. Suitable DOPO derivatives can also be incorporated into the chains of polyurethane copolymers as flame retardants, as described in the WO 2016/ 008074 A1 is shown for polyurethanes made from water. In the DE 10 2009 020 211 A1 A polyester used to manufacture molded parts is produced by polycondensation and, in a second step, compounded with a di- or polyfunctional compound to obtain a polyester with a higher molecular weight. The functional compounds serve to extend the chain and control the material properties, but have no other functionalities (e.g., flame-retardant effects). In the EP 2 144 950 B1 Halogen-free, non-reactive flame retardants based on phosphorus-containing polyesters, for example according to formula (I), are provided which are non-toxic and can be processed well as a masterbatch together with thermoplastic molding compounds in melt spinning processes or other extrusion processes at elevated temperatures. These phosphorus-containing polyesters are obtained by polycondensation of phosphorus-containing monomers with ester-forming monomers. The phosphorus-containing monomers are selected from the addition products of 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO) and core-substituted DOPO derivatives to unsaturated compounds from the grou