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
  • 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
• • 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
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber

Definitions

• the invention relates to a method for producing hydrolysis-stabilized monofilaments from post-condensed polyester granules with a viscosity index (VI) of at least 90 ml / g and their use in fabrics for the food, pharmaceutical and paper industries.
• VI viscosity index
• polyester fabrics are mainly used for economic reasons. Modern production plants in the food industry are run faster and at elevated temperatures. The conditions under which the conveyor belts or filter fabrics are used require good hydrolysis resistance of the materials because of the often high temperatures and high humidity. It is known that pure, post-condensed polyethylene terephthalate in moist hot medium is not resistant to hydrolysis and thus only partially meets the requirements of the food industry. In addition, the polyester monofilaments must not contain any toxic additives.
• Polyester is understood to mean thermoplastics which have at least 95% by weight of polyethylene terephthalate, polybutylene terephthalate and polynaphthalate units. It has long been known to increase the resistance to hydrolysis of polyethylene terephthalate by adding carbodiimides. They also lead to a satisfactory hydrolysis resistance of the polyester, but are toxic, lead to skin irritation and deterioration in the degree of whiteness.
• DE-A-19 526 405 discloses a process for reducing the carboxyl end groups of polyester.
• alkylene carbonate with allyltriphenylphosphonium bromide as catalyst is preferably used in the feed line to the post-condensation reactor.
• the known method serves for the thermal stabilization and color stabilization of a polyester.
• the known post-condensed polyester granulate is said to be suitable for the production of high-strength yarns for tire cord, which generally consist of multifilaments. Such yarns must be thermally stable and change color as little as possible during vulcanization, but are hardly exposed to moist heat. Only the post-condensed polyester granulate is intended as the starting material for the production of high-strength yarns. However, no information is given about the production of the yarns and their tensile strength. The production of monofilaments is not revealed.
• the known method has the disadvantage that the post-condensed polyester granulate has to be melted again in order to produce yarns.
• thermal degradation takes place with the formation of gas bubbles, which in a thread, in particular in a monofilament, can lead to a disturbance in the polyester structure and thus to inhomogeneity.
• Halides are also used as catalysts, which have the disadvantage that they cause discoloration even in the smallest amounts and that Disposal by burning form toxic acid gases (HC1, HBr).
• a method for reducing the carboxyl end groups of polyester for the production of monofilaments is known from US Pat. No. 3,657,191. It mentions the possibility of using ethylene carbonate without describing exemplary embodiments. All examples were carried out with monofunctional glycidil ether. The known method does not allow any comparison with the results obtained.
• a disadvantage in the known method is the long reaction times for blocking the carboxyl end groups.
• the object of the invention is the production of hydrolysis-resistant, atoxic, homogeneous monofilaments, which have no inclusions or thick spots, from polyesters for use in the food, pharmaceutical and paper industries.
• Another object is to produce a polyester monofilament that has improved hydrolysis resistance over the prior art.
• Yet another object is to use the hydrolysis-stabilized polyester monofilament to manufacture fabrics for conveyor belts and filter fabrics for the food, pharmaceutical, and paper industries.
• the object is achieved in that a polyester granulate having a viscosity index (VI) of at least 90 ml / g is metered in continuously with a liquid additive mixture of ethylene carbonate and an alkylphosphonium salt immediately before the extruder.
• the continuous addition to the granulate ensures good homogenization with a surprisingly short reaction time.
• the commercially available product with a melting point of about 39 ° C. is used as ethylene carbonate (EC) (1, 3-dioxalan-2-one). It is manufactured from ethylene oxide and liquid carbon dioxide. According to the "Registry of Toxic Effects of Chemical Substances" from the US Department of Health, Education and Weifare, ethylene carbonate is considered to be harmless. In addition, only CO 2 gas is released during the reaction in the polyester. The remaining glycol residue is deposited on the polyester end group.
• Alkyl or arylphosphonium salts such as tetrabutylphosphonium acetate (TBPA) are suitable as catalysts. They serve as catalysts for blocking the carboxyl end groups of the polyester.
• TBPA tetrabutylphosphonium acetate
• liquid additive from 0.15% by weight to 0.5% by weight of ethylene carbonate and 0.005% by weight to 0.025% by weight, in particular 0.010% by weight to 0.020% by weight, preferably 0.11% by weight. % to 0.15% by weight of an alkylphosphonium salt, based on the polyester granulate, to be used. If the catalyst is less than 0.005% by weight, the residual tensile strength is too low; at more than 0.025% by weight, the residual tensile strength is also too low and the monofilament cannot be used for technical purposes.
• the polyester monofilament has a residual tensile strength after a treatment of 6 days in water at a temperature of 125 ° C. of more than 55% and a viscosity index of at least 75 ml / g, which means a significant improvement in the hydrolysis resistance of monofilaments compared to the prior art , Me.q.q methods:
• Pei ss raff measured as maximum tensile force in N according to DIN 53 834, Part 1, p. 177.
• the monofilaments were treated in an autoclave at 125 ° C in water for between 3 and 8 days. After the hydrolysis, the temperature was reduced to below 100 ° C., the threads were removed and the residual tensile strength was determined.
• hydrolysis-resistant monofilaments made of polyester is particularly suitable for the production of fabrics for use in the food, pharmaceutical and paper industries.
• hydrolysis-resistant polyester is not limited to the production of monofilaments, but can generally be used for industrial yarns.
• a post-condensed polyethylene terephthalate in granular form with a granular viscosity VI of 98 ml / g serves as the starting polymer for all examples.
• This granulate is melted in an extruder and extruded through spinnerets into monofilaments with a diameter of 0.50 mm.
• the monofilaments were on conventionally cooled in water, stretched, relaxed, provided with a preparation and wound up.
• EC ethylene carbonate puriss.
• TBPA tetra-n-butylphosphonium acetate
• PET polyethylene terephthalate
• EC ethylene carbonate puriss.
• TBPA tetra-n-butylphosphonium acetate
• PET polyethylene terephthalate
• Fig. 1 course of the residual tensile strength (RK%) with and without the additive according to the invention.
• Fig. 2 residual tensile strength as a function of the amount of catalyst after 6 days of treatment in water at 125 ° C and 1.5 bar.
• curve 1 shows the course of the residual tensile strength [%] of a known polyester monofilament without addition over the course of time
• Curve 2 shows the course of the monofilament according to the invention.
• the residual tensile strength is a function of the amount of catalyst after treatment in water at 125 ° C and 1.5 bar recorded over 6 days.
• the resistance to hydrolysis expressed in percent residual tensile strength depending on the catalyst concentration, passes through a maximum at about 0.14 g / kg and thus corresponds to the optimal amount.
• Ethylene carbonate for the esterification of the COOH groups of the polyester gave surprisingly low COOH values and good color on the monofilament.
• polyester monofilaments according to the invention surprisingly have, after treatment in water at 125 ° C. after 6 days, a significantly improved tensile strength compared to known non-hydrolysis-stabilized monofilaments.

Landscapes

• 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)
• Woven Fabrics (AREA)
• Paper (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Cites Families (5)

• 2000
  • 2000-11-14 JP JP2001542617A patent/JP3860472B2/ja not_active Expired - Fee Related
  • 2000-11-14 EP EP00972531A patent/EP1244829B1/fr not_active Expired - Lifetime
  • 2000-11-14 US US10/088,617 patent/US6528161B1/en not_active Expired - Fee Related
  • 2000-11-14 AT AT00972531T patent/ATE259435T1/de not_active IP Right Cessation
  • 2000-11-14 WO PCT/CH2000/000606 patent/WO2001040554A1/fr active IP Right Grant
  • 2000-11-14 ES ES00972531T patent/ES2215077T3/es not_active Expired - Lifetime
  • 2000-11-14 DE DE50005286T patent/DE50005286D1/de not_active Expired - Fee Related
  • 2000-11-14 PT PT00972531T patent/PT1244829E/pt unknown

Non-Patent Citations (1)

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