WO1997035903A1 - Process for direct chemical modification of (co)polyesters - Google Patents

Abstract

The invention concerns a process for direct chemical modification of (co)polyesters in which at least one monomer compound of general formula (I) or (II) where G = a chemical group containing at least one polyester-foreign heteroatom selected from the group P, N and S; and R = reactive bond of the type lactone in a 4-, 7-, or 8-ring or cyclic anhydride or epoxide, is mixed in an application-determined quantity of up to 10 mol % with respect to the repeating polyester units, with (co)polyester or (co)polyester melt, optionally together with additional compounds, and mixed at 260 DEG C in a closed system which is blocked off against gas exchange and at a pressure greater than the steam pressure of the compounds used, with the (co)polyester melt which is produced by melting or is already existing. The group is built into the (co)polyester or bound to it through a reaction, and after a total reaction and residence time of less than 30 minutes, the chemically modified (co)polyester melt is processed further or withdrawn from the furnace, granulated and then further processed.

Description

"Process for the direct chemical modification of (co) polyesters"

description

The invention relates to a new, simple method for the direct chemical modification of (co) polyesters and products, in particular fibers and filaments, produced from them inherently flame-retardant or otherwise modified (co) polyesters

The components required for the production of polyesters, ie monomers, comonomers, catalysts, stabilizers, additives, etc., are usually already added to the reaction vessels, ie during the esterification or transesterification or polycondensation, because this is in the finished, highly viscous polyester melt Most of the time it would no longer be possible. Subsequent admixtures concern practically only inert additives which are incorporated into the polyester melt in the form of so-called masterbatches or, in some circumstances, also in a pure, dry form during further processing by means of extruders

Today, polyesters, especially PET (polyethylene terephthalate), are manufactured in large, continuous plants, which are in themselves too inflexible to produce different polyester quaternates within a short time. For example, if from one type with additional component X to another type If additional components Y have to be converted, large transitional quantities outside the specification arise. Therefore, the concept was developed to carry out polymer modifications only after the final reactor in order to simultaneously produce different polymer quantities for the various uses from the main melt stream divided into a corresponding number of substreams The latter concept is already used for physical modifications, ie the dispersion of inert solid additives (DE 40 39 857 C2). One possibility of subsequently converting PET into CoPET by means of chemical modification was described in DE 44 29 524 A1. Subsequent modifications of polyesters by chemical reaction without an actual reactor are severely restricted because the usual comonomers without the presence of polycondensation conditions (vacuum) greatly reduce the molecular weight of the polyester because the low molecular weight released by the reaction of the comonomers By-products (eg water) cannot be removed from the melt and cleave polymer chains by back reaction.

Flame retardancy is a special variant of polyester modification. Flame retardants make the polyester flame-retardant. For some purposes (e.g. for public transport), legislation in certain countries even prescribes flame-retardant properties for textile materials. An overview of the current situation and future developments is provided by J. Troitzsch's article: Flame retardant polymers - current Status and future trends, Makromol. Chem., Macromol. Symp. 74 (1993) pp. 125-135. Among other things, it states that many effective flame retardants can no longer be used today or in the future for ecological or toxicological reasons. Phosphorus-containing retarders are not affected by such requirements. As mentioned in the publication, phosphorus has a flame-retardant effect in practically all forms, regardless of its oxidation state or the exact nature of the phosphorus compound.

Phosphorus-containing flame retardants have hitherto been distributed, in part as pure additives which do not react with the polymer, in the polymer matrix, as described, for example, in DE 44 12 969 C1 under Example 8 for a flame-retardant PET hollow fiber. The disadvantage of a flame retardant that is only dispersed in the polyester is that repeated, extreme washing or

In some cases, the flame retardant of such fibers is treated for cleaning is extracted again

If high demands are placed on the washing and cleaning resistance of the flame retardant, chemical anchoring of the phosphorus compound in the polymer molecules is necessary

Phosphorus compounds must therefore have functional groups that can be linked to the polymer

Such a compound is, for example, 2-methyl-2,5-dioxo-1-oxa-2-phospholane, often called phospholane for the sake of simplicity. This compound is described in a product information from Hoechst from March 1979. To incorporate phospholane in polyester in order to be able to open the ring structure at the ester formation. Because the 5-ring is fairly stable, ie not very reactive, the ring opening only takes place under relatively harsh reaction conditions and initially only with low molecular weight compounds, specifically in the case of polyester that the phospholane must be added to one of the reactors in polyester production, where there is sufficient time to first react with ethylene glycol with the ring open before it can then be built into the polyester chains under polycondensation conditions. This means that a modified polyester not directly, but indirectly via two successive chemical reactions, based on the monomers of the polyester. The resulting polyester and the staple fibers and filament yarns produced from it are described in an article by K Rostermuπdt. Practical experience in dyeing flame-retardant modified polyester fibers, chemical fibers / textile industry, 43/95 year, January / February 1993, pp 65-68

Polyesters modified with phospholane and fibers and game which can be produced therefrom have therefore already been described, but the process for chemical modification described above is cumbersome and therefore cost-intensive According to this prior art, the polycondensation reactor is "contaminated" with the relevant phosphorus compound during the chemical flame-resistant modification, which is associated with the aforementioned disadvantage of so-called "off-spec" transition quantities when converting to other polyester types

In order at least to be able to give the user the possibility of being able to use chemically bound flame retardants flexibly and subsequently (without a polycondensation reactor), polymeric phosphorus-containing flame retardants have recently been developed which chemically contain a high proportion of phosphorus-containing subunits in a copolyester is bound, but this copolyester is in turn mixed as an additive, ie as a master batch, with the flame-retardant polyester to be finished, so that a blend is formed from which the end product can be produced

Such a product and a process for the production thereof are described in EP-A-0 547 701. The polymeric flame retardant is produced by polycondensation from an aromatic dicarboxylic acid, an alkylene glycol and a phosphorus-containing monomer, which is a linear copolyester with a high bond in the macromolecule Phosphorus content gives carboxyphosphinic acids and the corresponding cyclic anhydrides, ie lactones, are described as suitable phosphorus-containing monomers, the cyclic compound preferably being a 5-membered ring. A polycondensation reactor is therefore still required for the production of this special copolyester and is used by the user the flame-retardant polyester, for example polyethylene terephthalate or polybutylene terephthalate, is not chemically modified, but the polymeric flame retardant is simply mixed in in a certain proportion and then distributed (see Examples 7 to 9)

The situation is similar with US-A-5,530,088, where a polymeric, phosphorus-containing flame retardant and the manufacturing process therefor is written. This manufacturing process also consists of esterification and polycondensation in a corresponding reactor, starting from a dicarboxylic acid, a diol and a phosphorus-containing compound, a special co-catalyst being used for the polycondensation. The phosphorus compounds described in US-A-5,530,088 are phenanthrene derivatives. This product is used in the same way as that of EP-A-0 547 701, namely by mixing it with the polyester, which is to be given a flame-retardant finish, to produce a polymer blend from which fibers can then be spun, for example.

In summary, it should be noted that even the latest state of the art (e.g. EP-A-0 547 701, US-A-5,530,088) describes cumbersome processes for obtaining flame-retardant polyesters, but the phosphorus is not actually there Base polymer, but is copolymerized in an admixed, special copolyester.

It is therefore an object of the invention to provide inherently flame-retardant or otherwise modified (co) polyesters by means of a simpler process without the aforementioned disadvantages of the prior art

This object is achieved by the method having the features of claim 1, the modified polyesters of claims 8 and 9 and their use according to claims 10 and 11.

The above problem could be solved according to the invention in that at least one monomeric compound of the general formula (I) or (II)

(0 G (II)

CR> ^{■ "} ^ S

R with G = chemical group, containing at least one heteroatom foreign to polyester, selected from the group P, N and S.

R = reactive bond of type

■ Lactone in a 4-, 7- or 8-ring or

■ cyclic anhydride or ■ epoxy

in an application-related amount of up to 10 mol%, based on the repeating polyester units, optionally metered in together with further compounds, the polyester or the polyester melt and in a system which is closed against gas exchange and is at a higher pressure than the vapor pressure of the compounds used the polyester melt produced by melting or already present is mixed at at least 260 ° C., the group is reactively incorporated into or bound to the polyester, and after a total reaction and residence time of less than 30 minutes, the chemically modified polyester melt is further processed or discharged , granulated and subsequently processed

The formula (I) means that the chemical group G which carries the heteroatom forms a common ring with the reactive group R, ie the heteroatom is part of the ring. The formula (II) means that the chemical group G, which carries the heteroatom, is substituted on a ring with the reactive bond R.

The process according to the invention with the monomeric compounds of the formulas (I) and (II) has the essential advantage over the known types of modification that these compounds can be administered via the reactive bond R directly and within a short time, with or without a catalyst, react with the ester or end groups of the polyester and no by-products which reduce viscosity are split off, which means that the process as a whole does not require a polycondensation stage

According to the invention, groups with heteroatoms could thus be elegantly incorporated into the (co) polyester chains (main chain π) for the first time (if a compound of the formula (I) is used) or permanently bound to the polyester chains by chemical bonding (if a compound of the formula (II ) is used) so that inherently flame-retardant or otherwise modified (co) polyesters can be obtained therefrom. It is advantageous in the process according to the invention that the groups can be inserted or attached after the polyester has been produced and that the polycondensation system is not contaminated full flexibility and free choice to easily modify a base polyester

The heteroatoms contained in the chemical groups are P, N and S, and particularly preferably P phosphorus-containing groups, as described above, are particularly suitable for flame retardancy. Certain nitrogen-containing groups can also be used for the same purpose. Sulfuric acid group or its salt compound is particularly interesting for sulfur, because the polyester can be colored cationically by chemical modification with corresponding compounds. Conversely, polyester could be colored anionically by chemical modification with compounds of the formula (II) containing amino groups

Suitable polyesters are all thermoplastically processable polyesters, such as, for example, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPT (polypropylene terephthalate), PEN (polyethylene naphthalate), their copolyesters or already in some way in the course of production Modified polyesters (eg with pentaerythnt for branching) The term polyester means both homo-polyester and copolyester. PET is particularly preferred

Examples of compounds of the formula (I) are 3-methyl-3-oxo-3-phospha-

3-hydroxypropaneurelactone mentioned Examples of compounds of the formula (II) are 3- (9,10-dihydro-9-oxa-10-oxid-10-phosphaphenanthrene-10-yl) methyl-6-hydroxyhexaneurelactone, 2- (9th , 10-Dιhydro-9-oxa-10-oxιd-10- phosphaphenanthren-10-yl) -methyl-bernsteιnsaureaπhydrιd, dasNatrιumsalzdes 4-sulfophthalic anhydride or 3-Glycιdoxy-methoxy-phenylphosphιnoxιd

The method according to the invention is described in more detail below

The system, which is sealed against gas exchange and is at a higher pressure than the vapor pressure of the compounds used, can be either

Extruder (if polyester granulate is assumed), as well as a simple pipe through which the polyester melt flows, which is provided with a metering opening and downstream with a mixing device. If more than one connection is used, the minimum system pressure depends on the connection the highest vapor pressure Dynamic mixers and preferably static mixers are used as mixers. The compounds which bring about the chemical modification are metered using suitable devices. In the case of a granulate melt extruder, the compounds in solid form (powder) can be added continuously to the granules entering the extruder In the case of the melt pipeline, the connections are advantageously melted separately and then pumped in liquid form continuously into the pipeline with the melt flow. In both cases, the polyester melt has already been dosed A temperature in the range from 5 ^" C above the melting point of the polyester to be modified to 310" C, but in any case at least 260 ^* C An advantageous variant of the process according to the invention is to connect it directly to a continuous polycondensation end reactor and to modify a branched-off partial stream of the entire polyester melt in the manner according to the invention. In the latter variant, it is also possible under certain circumstances, instead of the pipe device, with liquid addition of the

To use a device according to DE 40 39 857 C2 in connection with the entire partial stream, in which only a side stream of the partial stream to be modified is first modified in an in-ime masterbatch extruder and then back-mixed with the still unmodified part of the partial stream. This special variant is, however only applicable if the concentration of the metered

The connection in the side stream does not exceed a certain limit and the compound in contact with the melt in solid form is neither sublimed nor evaporated back from the dosing nozzle. Whether these conditions are fulfilled can be determined experimentally

The modified melt can be further processed into various products such as fibers, filaments, foils, injection molding, blow molding or extrusion articles. However, PET is preferably modified with phosphorus-containing compounds and further processed into flame-retardant fibers and filaments. Suitable processing techniques are melting spins , Injection molding,

Multi-component injection molding, extrusion, coextrusion, blow molding, deep-drawing, etc. For this purpose, additives, reinforcing agents and fillers such as glass fibers, carbon fibers, mineral reinforcing agents and fillers, antistatic agents, stabilizers, dyes, etc. can be added to the chemically modified polyesters Of course, only additives which do not impair the spinnability can be used for melt spinning

The following examples 1 to 6 in conjunction with FIGS. 1 to 6 serve to illustrate the invention. These show, by way of example but not by way of limitation, how compounds according to the inventive method can react with polyester in the melt state The figures show:

Figure 1 reaction between PET and a phosphorus-containing compound of formula (II) with R = 7-ring lactone

Figure 2 reaction between PET and a phosphorus-containing compound of formula (II) with R = cyclic anhydride

Figure 3 reaction between PET and a phosphorus-containing compound of formula (I) with R = 4-ring lactone

Figure 4 reaction between PET and a sulfur-containing compound of

Formula (II) with R = cyclic anhydride

Figure 5 reaction between the modified PET of Figure 2 and one

Monoepoxy compound

Figure 6 reaction between PET and a phosphorus-containing compound of formula (II) with R = epoxy

EXAMPLES

example 1

The reaction between PET and a compound A is shown in FIG. 1, the basic structure of which corresponds to formula (II) with a lactone bond (7-ring). The exact name of compound A is 3- (9, 10-dihydro-9-oxa-10-oxide-10-phosphaphenanthren-10-yl) methyl-6-hydroxyhexanoic acid lactone. By direct

The transesterification between the lactone bond and ester groups in PET becomes the phosphorus-containing group bound to the PET chain

Compound A is obtainable by Michael addition of DOP to 3-methylene-caprolactone. DOP is the abbreviation for 9, 10-dihydro-9-oxa-10-phosphaphen-anthrene-10-oxid. This substance was called DOP (95 ) from the company Schill & Seilacher GmbH, Boblingen (Germany)

The 3-methylene-caprolactone can be prepared by a synthetic route which is described by M Moπ et al in J Org Chem (1983), 48 (22), 4058-67 (Patladium-catalyzed carbonylation A new synthesis of alpha-methyiene gamma -

, delta-epsilon-lactams and lactones including bicyclic lactams of pyrrolizidine and indolizidme skeletons)

Compound A, for example, can be metered in powder form with a differential dosing weigher continuously to "textile grade" PET granules, which in the

Feed spigot of a spinning extruder is running For the purpose of flame retardancy, the dosing quantity should be selected so that the content of elemental phosphorus in the modified polyester or in the thread produced from it by melt spinning is approx. 0.6% by weight. This value can be the optimum between effort and effect regarding flame retardancy

The influence of the amount of phosphorus on the LOI value (ubiting oxygen index) of a product produced from the modified polyester has already been shown in EP 0 547 701 (Examples 7 and 8) and in US 5,530,088 (FIG. 1 and Table 2), where you can see that saturation occurs with higher amounts of phosphorus So that the reaction between compound A and the PET proceeds as completely as possible and the majority of the phosphorus is chemically bound to the polyester, a melt temperature in the range of 270 to 295 is advantageous ^* C set and a total reaction and residence time in the melt phase, ie calculated from melting in the extruder to the exit of the thread from the spinneret, of about 20 minutes, the usual pressures in the order of about 100 bar being maintained in this system they rule necessary residence time can be influenced by adding catalysts such as tin (II) dioctoate

Example 2

FIG. 2 shows how a compound B, which corresponds in its basic structure to the formula (II) with a cyclic anhydride bond, reacts with a hydroxyl end group of PET. The exact name of the compound B is 2- (9,10-dihydro-9 -oxa- 10-oxιd-10-phosphaphenanthren-10-yl) -methyl-bernsteιnsaureanhydrιd B is the addition product of DOP and itaconic acid from which the water has been removed

B was obtained from Schill & Seilacher GmbH in Boblingen (Germany) under the name DOP-ITS-Aπhydπd

Further information on connection B

_Molecular formula C ₁₇ H ₁₃ O ₅ P

Molecular weight 328.3 g / mol

Phosphorus content 9.4% by weight

Melting point about 184 ^* C

This connection can thus be melted and metered into the polyester melt flow in a pipeline by means of a pump.The temperature of the polyester melt is, for example, approx. 285'C and the pressure prevailing in the system, e.g. approx. 50 bar. A static mixer built into the pipeline can be used for mixing The resulting modified polyester can be spun directly from the melt into flame-retardant thread, whereby the same recommendations as for example 1 generally apply

When using anhydride compounds, the degree of modification that can be achieved is limited by the consumption of hydroxyl end groups of the polyester. How this disadvantage can be overcome in an inventive manner is described in Example 5

Example 3

In this example, as shown in Figure 3, the PET melt with a

Modified compound C, which corresponds in its basic structure to formula (I) with lactone bond (4-ring). The exact name of compound C is 3-methyl-3-oxo-3-phospha-3-hydroxypropauric acid lactone. The phosphorus is converted into directly by transesterification the main chain of the polyester is incorporated. The advantage of compound C is its high phosphorus content and the fact that, compared to the phospholane mentioned in the introduction to the description, no additional ethylene glycol is bound in the polyester chain. Implementation of the process and chemical reaction are analogous to Example 1, where in the case of a liquid metering with a pump into a melt line, any catalysts can be dissolved in the melted C.

Example 4

As an example of the heteroatom sulfur, FIG. 4 shows how a sulfonic acid group can be bonded to a polyester according to the invention so that it can be color-coated. Compound D is the sodium salt of 4-sulfophthalic anhydride, that is to say a compound of the formula (II) with a cyclic anhydride bond. Metering in to the polyester is possible in solid or liquid form. The reaction mechanism corresponds to example 2. Because of the consumption of hydroxyl end groups, the degree of modification is also initially limited, but can be expanded by the method described in example 5 become

Example 5

In order to overcome the disadvantage emphasized in Examples 2 and 4, preferably applied the following additional method according to the invention

In addition to the anhydride compound, a monoepoxide compound is added to the polyester, for example styrene oxide (compound E), as shown in FIG. 5. The monoepoxide compound preferably reacts with acid groups and thus converts COOH end groups into OH end groups

FIG. 5 shows by way of example how the new COOH end group additionally formed by modification with compound B (according to FIG. 2) is converted back into an OH end group using styrene oxide, both possible reaction products being shown

However, the styrene oxide can equally well react with an already existing COOH end group of the polyester (not shown) and in this way likewise increase the supply of OH end groups for the addition of the anhydride compound, which in the same direction increases the maximum possible Degree of modification and increased rate of modification is therefore particularly preferred for the gross reaction conversion, the simultaneous addition of the two compounds. If the anhydride and the monoepoxide compound are reacted in the same molar amounts, this also remains

Eπdgruppeπverhaltnis [-COOH] / [- OH] in the polyester unchanged in the modification

The effect of the additional monoepoxide addition was tested in laboratory tests in a laboratory autoclave. Matted polyethylene terephthalate type M762 ("textile grade") from EMS-CHEMIE AG (Domat / Ems, Switzerland) and DOP-ITS anhydride (compound B) from Schill & Seilacher GmbH (Boblmgen, Germany) and styrene oxide (compound E) from Fluka Chemie AG (Buchs, Switzerland). After melting the PET down to 290 ^' C, only variant B was used in variant 1 of 5.3% by weight

(or 3.2 mol%) based on the PET (molecular weight a PET unit = 192, 17 g / mol) added (corresponds to 0.5% by weight phosphorus based on the modified polyester) In a sample of the polyester taken after 20 minutes, a strongly increased acid number and a degree of incorporation or reaction conversion of (as expected due to the reaction mechanism) only approx. 80% measured. In test variant 2, which was otherwise carried out in the same way, an equimolar amount of styrene oxide was added simultaneously with compound B. After 20 minutes, virtually unchanged end group numbers were associated with an increase in the degree of embedding of the added compounds compared to the PET used Amount of B in the polyester analyzed This proved the positive effect of the monoepoxide on the rate of incorporation of the anhydride

Example 6

FIG. 6 shows how a compound F, which corresponds in its basic structure to the formula (II) with epoxy bond, reacts with an acid end group of PET. The exact name of the compound F is 3-glycidoxy-methoxy-phenylphosphine.

In only one compound, the compound F contains, as it were, the effect of an anhydride compound B combined with a monoepoxide. FIG. 6 shows both possible reaction products. Because hydroxyl groups can also react with epoxy groups (not shown), there is also a degree of modification for a polyester Compound F has no upper limits comparable to compound B.

Claims

"Process for the direct chemical modification of (co) polyesters" claims 1 . Process for the direct chemical modification of (co) polyesters by incorporation or attachment of chemical groups, in which at least one monomeric compound of the general formula (I) or (II) (I) G (II) G R with G = chemical group, containing at least one heteroatom foreign to polyester selected from the group P, N and S. R = reactive bond of type ■ lactone in a 4-, 7- or 8-ring or ■ cyclic anhydride or ■ epoxy in an amount of up to 10 mol%, based on the repeating polyester units, optionally together with other compounds from the group of the catalysts and the monoepoxide compounds, the (co) polyester or the (co) polyester melt and metered in in one against Gas exchange completed and under higher pressure than the vapor pressure of the connections used with the system mixed by melting or already existing (co) polyester melt at at least 260 ^" C, and after a total reaction and residence time of less than 30 minutes the chemically modified (co) polyester melt processed or discharged, granulated and subsequently is processed further A method according to claim 1, characterized in that the heteroatom in the compound of formula (I) or (II) is phosphorus A method according to claim 1 or 2, characterized in that a Compound of formula (I) or (II) with a cyclic anhydride bond is metered in together with a monoepoxide compound A method according to claim 1, characterized in that the polyester is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene naphthalate and their copolyester, and in particular polyethylene terephthalate Method according to claims 1 to 4, characterized in that the system closed against gas exchange is an extruder Method according to claims 1 to 4, characterized in that the system closed against gas exchange is a tube provided with a metering opening and downstream with a mixer, preferably a static mixer Process according to claims 1 to 6, characterized in that the temperature of the (co) polyester melt is in the range from 5 ^" C above the melting point of the (co) polyester to 310 ^' C. Chemically modified (co) polyester produced by the process according to one or more of claims 1 to 7 Chemically modified (co) polyester according to claim 8, characterized gekenn¬ characterized in that it is modified with phosphorus atoms modified polyethylene terephthalate Use of the chemically modified (co) polyester according to claim 8 or 9 for further processing into fibers, filaments, foils, injection molding, blow molding or extrusion articles Use of the chemically modified (co) polyester according to claim 9 for further processing into flame-retardant fibers and filaments CHANGED CLAIMS [Received at the international office on August 22, 1997 (August 22, 1997), original claim 1 changed; all other claims unchanged (3 pages)] Process for the direct chemical modification of (co) polyesters by incorporation or attachment of chemical groups, in which at least one monomeric compound of the general formula (I) or (II! R with G = chemical group, containing at least one heteroatom foreign to polyester selected from the group P, N and S. R = reactive bond of type ■ Lactoπ in a 4-, 7- or 8-Rιπg or ■ cyclic anhydride or Epoxy, with the proviso that the heteroatom is phosphorus, in an amount of up to 10 mol%, based on the repeating polyester units, optionally together with further compounds from the group of catalysts and the moleooxide Veroiπαuπgeπ, the (co) polyester or the (co) polyester melt and metered in one against Gas exchange completed and at higher pressure than the vapor pressure of the compounds used system with the produced by melting or existing (co) poiy9ster- melt blended at least 260 ^"C, and after a total action-Re and residence time less than 30 minutes, the chemically modifizier¬ te (co) ρolyesterschmeize further processed or discharged, granulated and subsequently is processed further. 2. The method according to claim 1, characterized in that the heteroatom in the compound of formula (I) or (II) is phosphorus. 3. The method according to claim 1 or 2, characterized in that a Compound of formula (I) or (II) with cyclic anhydride formation together with a monoepoxide compound is metered in 4 The method according to claim 1, characterized in that the polyester is selected from the group consisting of polyethylene terephthalate, polybutyl terephthalate, polypropylene terephthalate, polyethylene terephthalate and their copolyesters, and in particular polyethylene terephthalate. 5. The method according to claims 1 to 4, characterized in that the system closed against gas exchange is an extruder. 6. The method according to claims 1 to 4, characterized in that the system closed against gas exchange is a tube provided with a metering opening and downstream with a mixer, preferably a static mixer. 7. The method according to claims 1 to 6, characterized in that the temperature of the (co) polyester melt is in the range from 5 ^* C above the melting point of the (co) ραlyester to 310 ^" C. Chemically modified (co) polyester produced by the process according to one or more of claims 1 to 7 Chemiscn modified (Co) polyester naen Aπsoruch 8, characterized gekenn¬ characterized in that it is modified with Phosphoratomeπ Polyethyientereph-thalat Use of the chemically modified (co) polyester according to claim 8 or 9 for further processing into fibers, filaments, foils, injection molding, blow molding or extrusion articles Use of the cnemically modified (co) polyester according to claim 9 for further processing into flame-retardant fibers and filaments DECLARATION REFERRED TO IN ARTICLE 19 1 . The following publications are mentioned as state of the art in international research: D1: WO 95/24445 (Monsanto Company) D2: US 4, 1 1, 5.350 (Lazarus et al.) D3: DE 27 10 034 (Inventa AG). 2. The epoxy compounds used in the process according to the invention have now been restricted in such a way that the heteroatom for the epoxide is phosphorus. Only the compounds defined in claim 1 can be used in the "In Ine" process. In none of the documents D1 to D3 is an "In Iine" process for the direct chemical modification of (co) polyesters by incorporation or Connecting chemical groups described that neither a reactor nor Vacuum required and expires in less than 30 minutes. According to the invention, groups can thus be elegantly incorporated into the (co) polyester chains for the first time, so that inherently flame-retardant or otherwise modified (co) polyesters can be obtained therefrom. The subject of claims 1 to 1 1 is therefore both new and inventive. WO 95/24445 (Monsanto) (D1) describes (co) polyesters or flame-retardant textiles made from these plastics with flame-retardant compounds. The phosphorus-containing substances described there, most of which have free reactive groups, are reactively bonded to the recycled polyethylene terephthalate in a conventional manner in a reaction kettle and in the presence of ethylene glycol (cf. p. 3, lines 22 to 32). This process, which is known in the prior art and takes several hours, is quite cumbersome and cost-intensive since reactors are required which have to be operated under vacuum conditions. No. 4,115,350 (Allied) (D2) describes nitrogen- or sulfur-containing epoxy compounds with which polyesters are heat-stabilized in a reactive manner. No phosphorus-containing compounds are mentioned in D2. The nitrogen- and sulfur-containing compounds of D2 fall under the general formula II according to the invention with R = epoxide. However, according to column 3, lines 27 to 32 and according to claims 6 and 11, these can also be added after the end reactor of the polyester melt. DE 27 10 034 (Ems-Inventa) (D3) describes a process for the production of hydrolysis-stable shaped structures from polyesters by shaping the polyester material in the presence of compounds which reduce the carboxyl end group content of these polyesters. N-glycidylimides are used as compounds reducing the carboxyl end group content. However, D3 does not speak of compounds containing phosphorus with R = epoxide.