Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F1/00—General methods for the manufacture of artificial filaments or the like
  • D01F1/02—Addition of substances to the spinning solution or to the melt
  • D01F1/10—Other agents for modifying properties
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/62—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyesters

Definitions

• the invention relates to synthetic fibers made of polyesters, preferably polyester monofilaments, which have been stabilized against the thermal and in particular hydrolytic degradation by the addition of a combination of mono- and polycarbodiimides, and suitable processes for their production.
• polyester molecules are split in such a way that, for example in the case of polyethylene terephthalate, the ester bond is broken down to form a carboxyl end group and a vinyl ester, the vinyl ester then reacting further with the release of acetaldehyde.
• thermal decomposition is primarily influenced by the level of the reaction temperature, the residence time and possibly by the nature of the polycondensation catalyst.
• DE-OS 1 770 495 describes stabilized polyethylene glycol terephthalates, which were obtained by adding polycarbodiimides. Because of the slower reaction rate generally observed with polycarbodiimides, it is necessary to ensure that the polycarbodiimide remains in the polyester melt for a longer time. For this reason, polycarbodiimides have already been added in the polycondensation reaction of the polyesters. However, such an approach has a number of disadvantages. For example, a large number of by-products arise due to the long residence time, and the actual polycondensation reaction of the polyester may also be hindered.
• the two last-mentioned designs are specifically designed for the production of stabilized polyester filaments, with a slight excess of carbodiimide in the finished thread being recommended in both cases.
• the excess over the stoichiometrically required amount should be up to 7.5 m Val / kg polyester, while in JA-AS 1-15604 / 89 an excess of 0.005 to 1.5 wt .-% of the monocarbodiimide specifically recommended there.
• JP-AS 1-15604 / 89 it is of particular importance for the desired thermal and hydrolytic resistance of threads produced therefrom that free carbodiimide is still contained in the finished threads or monofilaments, since otherwise, for example, under the very aggressive conditions in a paper machine such materials would soon be unusable.
• the JP-AS also shows that the use of polycarbodiimides does not correspond to the state of the art that has already been achieved.
• a disadvantage of all previously known processes which work with an excess of mono- or biscarbodiimides is that, due to the volatility of these products, which cannot be neglected, and in particular that of the thermally and hydrolytically produced cleavage products, e.g. the corresponding isocyanates and aromatic amines, a noticeable burden on operating personnel and the environment must be expected. Due to their special properties, stabilized polyester threads are usually used at higher temperatures and usually in the presence of water vapor. Under these conditions, such a burden can be expected from the excess additions of carbodiimide and secondary products. Because of their volatility, it is to be expected that these compounds will diffuse out of the polyester or can also be extracted, for example, by solvents or mineral oils. A sufficient deposit effect is therefore not guaranteed in the long run.
• the invention therefore relates to polyester fibers and filaments in which the carboxyl end groups are mainly sealed by reaction with mono- and / or biscarbodiimides, but the fibers and filaments according to the invention contain only very small or no amounts of these carbodiimides in free form.
• the polyester fibers and filaments it is necessary for the polyester fibers and filaments to contain at least 0.05% by weight of at least one polycarbodiimide, this polycarbodiimide should be present in free form or with at least some reactive carbodiimide groups.
• the desired polyester fibers and filaments with significantly improved resistance to thermal and / or hydrolytic attack should contain less than 3 meq / kg carboxyl end groups in the polyester. Fibers and filaments in which the number of carboxyl end groups has been reduced to less than 2, preferably even less than 1.5 meq / kg polyester are preferred.
• the content of free mono- and / or bis-carbodiimides should preferably be 0 to 20, in particular 0 to 10 ppm (weight) polyester.
• the fibers and filaments still contain polycarbodiimides or their reaction products with groups which are still reactive. Concentrations of 0.1 to 0.6, in particular 0.3 to 0.5% by weight of polycarbodiimide in the polyester fibers and filaments are preferred.
• the molecular weight of suitable carbodiimides is between 2000 and 15000, preferably between 5000 and about 10000.
• polyesters which have a high, medium molecular weight, corresponding to an intrinsic viscosity (intrinsic viscosity) of at least 0.64 [dl / g].
• the measurements were carried out in dichloroacetic acid at 25 ° C.
• the process according to the invention for producing the stabilized polyester fibers and filaments claimed consists in the addition of mono- and / or biscarbodiimide in an amount which corresponds at most to the stoichiometrically required amount, calculated from the number of carboxyl groups, and additionally an amount of at least 0. 15% by weight, based on polyester, of a polycarbodiimide.
• This mixture of polyester and carbodiimides can be spun into threads and monofilaments or staple fibers in a known manner and processed further.
• the stoichiometric amount is the amount in milliequivalents per unit weight of the polyester which can and should react with the terminal carboxyl groups of the polyester.
• polyesters to be used should have less than 20, preferably even less than 10 meq carboxyl end groups per kg. The increase due to the melting has already been taken into account in these values. Polyesters and carbodiimides should not be stored for as long as desired at high temperatures. It was pointed out above that additional carboxyl end groups are formed when polyesters are melted. The carbodiimides used can also decompose at the high temperatures of the polyester melts.
• melt extruders it is possible to reduce this residence time in the molten state to less than 5, preferably less than 3 minutes.
• the melting time in the extruder is limited only by sufficient mixing of the reactants for a perfect reaction between carbodiimide and polyester carboxyl end groups. This can be done by designing the extruders appropriately or, for example, by using static mixers.
• thread-forming polyesters are suitable for use in accordance with the present invention, ie aliphatic / aromatic polyesters such as, for example, polyethylene terephthalates or polybutylene terephthalates, but also completely aromatic and, for example, halogenated polyesters can be used in the same way.
• Modules of thread-forming polyesters are preferably diols and dicarboxylic acids or correspondingly constructed oxycarboxylic acids.
• the main acid component of the polyesters is terephthalic acid, of course, other compounds which are preferably para or trans, such as 2,6-naphthalenedicarboxylic acid or p-hydroxybenzoic acid, are also suitable.
• Typical suitable dihydric alcohols would be, for example, ethylene glycol, propanediol, 1,4-butanediol but also hydroquinone etc.
• Preferred aliphatic diols have two to four carbon atoms.
• Ethylene glycol is particularly preferred.
• Longer-chain diols can, however, be used in proportions of up to approximately 20 mol%, preferably less than 10 mol%, for modifying the properties.
• polyester fibers and filaments according to the invention which consist predominantly or entirely of polyethylene terephthalate and in particular those which have a molecular weight corresponding to an intrinsic viscosity (intrinsic viscosity) of at least 0.64, preferably at least 0.70 [dl / g].
• the intrinsic viscosities are determined in dichloroacetic acid at 25 ° C.
• the filaments or fibers of the invention are stabilized by adding a combination of a mono- and / or biscarbodiimide on the one hand and a polymeric carbodiimide on the other hand.
• the use of monocarbodiimides is preferred, since they are distinguished in particular by a high reaction rate in the reaction with the carboxyl end groups of the polyester.
• the carboxyl groups still remaining in the polyesters after the polycondensation are said to be predominantly by reaction with a mono- or Biscarbodiimide be closed.
• a smaller proportion of the carboxyl end groups will also react with carbodiimide groups of the additionally used polycarbodiimide under these conditions according to the invention.
• the polyester fibers and filaments according to the invention therefore essentially contain their reaction products with the carbodiimides used instead of the carboxyl end groups.
• Mono- or bis-carbodiimides which are only allowed to be found in the fibers and filaments in free form to a very small extent, if at all, are the known aryl, alkyl and cycloalkyl carbodiimides.
• the diarylcarbodiimides which are preferably used, the aryl nuclei can be unsubstituted.
• aromatic carbodiimides substituted and thus sterically hindered are preferably used in the 2- or 2,6-position.
• DE-AS 1 494 009 already lists a large number of monocarbodiimides with steric hindrance to the carbodiimide group.
• monocarbodiimides for example, the N, N ′ - (di-o-tolyl) carbodiimide and the N, N ′ - (2,6,2 ′, 6′-tetraisopropyl) diphenylcarbodiimide are particularly suitable.
• Biscarbodiimides which are suitable according to the invention are described, for example, in DE-OS 20 20 330.
• suitable polycarbodiimides are compounds in which the carbodiimide units are connected to one another via mono- or disubstituted aryl nuclei, phenyl, naphthylene, diphenylene and the divalent radical derived from diphenyl methane being suitable as aryl nuclei and the substituents according to type and place of substitution being the substituents of the mono-diarylcarbodiimides substituted in the aryl nucleus.
• a particularly preferred polycarbodiimide is the commercially available aromatic polycarbodiimide which is substituted with isopropyl groups in the o-position to the carbodiimide groups, ie in the 2,6- or 2,4,6-position on the benzene nucleus.
• the free or bound polycarbodiimides contained in the polyester filaments according to the invention preferably have an average molecular weight of from 2000 to 15,000, but in particular from 5,000 to 10,000. As already stated above, these polycarbodiimides react with the carboxyl end groups at a significantly lower rate. If such a reaction occurs, preferably only one group of the carbodiimide will initially react. However, the other groups present in the polymeric carbodiimide lead to the desired depot effect and are the cause of the substantially improved stability of the fibers and filaments obtained.
• polyester fibers and filaments produced according to the invention can contain conventional additives such as e.g. Contain titanium dioxide as a matting agent or additives, for example, to improve the dyeability or to reduce electrostatic charges.
• additives or comonomers are of course also suitable which can reduce the flammability of the fibers and filaments produced in a known manner.
• colored pigments, carbon black or soluble dyes can also be incorporated or already contained in the polyester melt.
• other polymers such as polyolefins, polyesters, polyamides or polytetrafluoroethylenes, it is possible to achieve completely new textile-technical effects if necessary.
• cross-linking substances and similar additives can also bring advantages for selected areas of application.
• polyester fibers and filaments are required to produce the polyester fibers and filaments according to the invention.
• This melting can preferably take place in the melt extruder directly before the actual spinning process.
• the carbodiimides can be added by adding them to the polyester chips, impregnating the polyester material before the extruder with suitable solutions of the carbodiimides, but also by breading or the like.
• Another type of additive is in particular for metering in the polymeric carbodiimides, the production of master batches in polyester (masterbatches). These concentrates can be used to mix the polyester material to be treated directly in front of the extruder or, if a twin screw extruder is used, for example, in the extruder. If the polyester material to be spun is not in chip form, but is, for example, continuously supplied as a melt, appropriate metering devices for the carbodiimide, if necessary in molten form, must be provided.
• the amount of the monocarbodiimide to be added depends on the carboxyl end group content of the starting polyester, taking into account the additional carboxyl end groups which are likely to be formed during the melting process. In order to achieve the desired minimal impact on the environment and on the operating personnel, it is preferable to work with substoichiometric amounts of mono- or biscarbodiimides.
• the amount of mono- or biscarbodiimides added should preferably be less than 90% of the stoichiometrically calculated amount, in particular 50 to 85% of the stoichiometric amount of the mono- or biscarbodiimide corresponding to the carboxyl end group content.
• a preferred form of addition for the Polycarbodiimide represents the addition of stock batches which contain a higher percentage, for example 15%, of polycarbodiimide in a conventional polymeric polyester granulate.
• the residence time of the carbodiimides in the melt should preferably be less than 5 minutes, in particular less than 3 minutes.
• the amounts of mono- or bis-carbodiimide used react well in a quantitative manner, i.e. they can then no longer be detected in free form in the pressed threads.
• some of the carbodiimide groups of the polycarbodiimides used react, albeit to a significantly lower percentage, but they primarily take on the depot function.
• polymeric carbodiimides for long-term stabilization, in addition to the lower thermal decomposability and lower volatility of these compounds, there is also a considerably greater degree of safety toxicological. This applies in particular to all the polymer molecules of polycarbodiimides which have already been chemically bonded to the polyester material with at least one carbodiimide group via a carboxyl end group of the polyester.
• the carbodiimide was mixed with the masterbatch and the polymer material in containers by mechanical shaking and stirring. This mixture was then placed in a single-screw extruder from Reifen Reifenberger, Germany, type S 45 A.
• the individual extruder zones had temperatures of 282 to 293 ° C., the extruder was operated with a discharge of 500 g of melt / min using conventional spinnerets for monofilaments. Residence time of the mixtures in the molten state 2.5 min.
• the freshly spun monofilaments were quenched in a water bath after a short air gap and then continuously stretched in two stages. The draw ratio was 1: 4.3 in all tests.
• the temperature during the drawing in the first stage was 80 ° C. and in the second stage 90 ° C., the running speed of the spun threads after leaving the quenching bath was 32 m / min. Thereafter, heat-setting was carried out in a fixing channel at a temperature of 275 ° C. All spun monofilaments had a final diameter of 0.4 mm.
• a monofilament was again produced under the same conditions as in Example 1, but with 0.6% by weight of the N, N '- (2,6,2', 6'-tetraisopropyl-diphenyl) -carbodiimide alone as a closing agent for the carboxyl groups was used.
• the amount of 0.6% by weight corresponds to a value of 16.6 meq / kg, so an excess of 10.2 meq / kg polymer was used.
• a polyester monofilament is obtained which shows very good stability against thermal hydrolytic attack.
• the free monocarbodiimide content of 222 ppm in the finished products is disadvantageous.
• Example 1 was also repeated here for comparison purposes. This time, however, an amount of 0.876% by weight of the polycarbodiimide described above was added in the form of a 15% masterbatch. This experiment was carried out in order to check again the information in the previous literature, according to which even with a noticeable excess of polycarbodiimide, presumably due to the low reactivity, a reduced thermal and hydrolytic resistance can be observed, compared to the prior art. This example clearly shows that this is actually the case. It is interesting that this selected amount of polycarbodiimide already seems to lead to a noticeable crosslinking of the polyester, as can be deduced from the significant increase in the intrinsic viscosity values. In general, such crosslinking is only permissible within narrow limits for thread-forming polymers if it is strictly reproducible and no spinning difficulties or difficulties in stretching the threads produced therefrom are to be expected.
• Example 1 The procedure according to Example 1 or Example 2 was repeated, but now amounts of monocarbodiimide were added which result from the stoichiometrically calculated value or a 20% excess of monocarbodiimide.
• the results obtained here are also shown in the following table.
• In run 4a exactly the stoichiometrically required amount of monocarbodiimide was added, while in run 4b an excess of 1.3 meq / kg of monocarbodiimide was used.
• the relative residual strengths found after treatment at 135 ° C. in a steam atmosphere after 80 hours do not correspond to the prior art.
• Example 1 was repeated, but this time, in addition to monocarbodiimide, a polycarbodiimide was also used according to the invention.
• the amount of monocarbodiimide added was only 5.5 mVal / kg, ie a deficit of 0.9 mVal / kg, calculated on the stoichiometric requirement, was used. Expressed as a percentage, this is a deficit of 14.1% or only 85.9% of the stoichiometrically required amount was added.
• the free monocarbodiimide content is within the desired limits under these conditions, but in particular the thermal-hydrolytic resistance within the error limits is readily comparable to the best known compositions to date.
• Example 5 was repeated as run 5b, but this time with the addition of exactly the equivalent amount of monocarbodiimide and the addition of polycarbodiimide in the concentration range claimed.
• the relative residual strength found was not influenced by the increase in the monocarbodiimide content. Only a slight increase in the free monocarbodiimide content was observed.
• Example 5 was reworked, but this time with an excess of monocarbodiimide addition of 1.3 meq / kg, or 20% more than required by the stoichiometry. A corresponding excess has already been used in run 4b. Under the chosen conditions it is shown that this amount already has an undesirably high free monocarbodiimide content of 33 ppm, i.e. thus significantly more than observed in runs 5a and 5b. Such a value should actually no longer be tolerated, since it was shown in the runs of Example 5 that the same relative residual strength, i.e. So the same thermal hydrolytic resistance can also be achieved with a lower content of free monocarbodiimide and thus a lower pollution of the environment.
• the test results and reaction conditions are summarized in the table below.
• the monocarbodiimide additive is expressed once as a weight percent additive, then, given in a second column in mVal / kg.
• the excess or: deficit of monocarbodiimide additive compared to the stoichiometric calculation is given, then in the next column the addition of polycarbodiimide is noted in percent by weight.
• Further columns show the measured values of the monofilaments obtained, each of which had a diameter of 0.40 mm. First the amount of carboxyl end groups is given in mVal / kg, then the amount of free monocarbodiimide in ppm (weight values). The free carbodiimide content was determined by extraction and gas chromatographic analysis, similar to that described in JP-AS 1-15604-89. Further columns follow in which the relative residual strength and the intrinsic viscosity of the individual thread samples are given.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Artificial Filaments (AREA)
• Polyesters Or Polycarbonates (AREA)
• Paper (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
• Chemical Treatment Of Fibers During Manufacturing Processes (AREA)
• Polyamides (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

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• 1989
  • 1989-09-15 DE DE3930845A patent/DE3930845A1/de not_active Withdrawn
• 1990
  • 1990-09-11 DE DE59010270T patent/DE59010270D1/de not_active Expired - Fee Related
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