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
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/18—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide
• • 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 threads and fibers made of polyacrylonitrile, the thread-forming substance of which consists of at least 98% by weight of acrylonitrile components and has a high average molecular weight.
• a special drawing and fixing process can be used to obtain threads and fibers which show increased resistance to swelling and hydrolysis processes even at elevated temperatures.
• Threads or fibers for reinforcement no longer show optimal properties if temperatures of approximately .100 ° C. are exceeded in the anhydrous medium, and temperatures of approximately 80 ° C. in an aqueous medium during the production of the composite materials. It can be assumed that under these conditions structural changes occur in the fibers, which make them more sensitive to the attack of the solvent, monomers and other primarily low molecular weight components located in the setting composite or which make them more sensitive to a hydrolytic attack Presence of water in the manufacture of fiber reinforced composites. Such sensitivity can be observed, for example, if the fiber-reinforced composite materials have hydraulically setting binders, i.e. the aqueous phase has an alkaline reaction. It is believed that the action of the solvent residues and monomers leads in particular to swelling at higher temperatures and also the reinforcing properties of the threads, i.e. in particular their initial modulus and fiber strength are reduced.
• threads and fibers can be obtained if their thread-forming substance consists of at least 98% by weight of acrylonitrile units and a relative viscosity, measured as a 0.5% by weight solution in dimethylformamide at 25 ° C in the range between 2.5 and 6.0, the threads are stretched before or after washing, dried under tension on hot rollers and post-stretched under the action of dry heat at 140 to 200 ° C, with a post-stretching of at least 1: 1.5 the total stretching should be at least 1: 9 and the threads after this post-stretching should be fixed without exposure to shrinkage by exposure to dry heat at 170 to 280 ° C.
• threads and fibers which have high tensile strengths of 50 to 100 cN / tex, preferably 55 to 80 cN / tex, low boiling shrinkage of less than 5%, preferably less than 3% and elongations at break of up to 15 , preferably a maximum of 12%.
• the fibers and filaments obtained also have excellent stability against swelling. and hydrolytically attacking media.
• aqueous alkaline medium prepared by extracting 150 g of Portland cement with 1 liter of water, and then washing and drying, the fibers still have an initial modulus of at least 900 cN / tex, preferably of at least 1000cN / tex, based on 100% elongation
• the threads and fibers according to the invention are particularly suitable. good as reinforcing threads or fibers or in the form of woven, knitted or non-woven fabrics for the production of reinforced organic or inorganic materials. These products are particularly advantageous for the production of hydraulic binder-containing products with a fine cavity structure. But they are also suitable for the production of filters or filter fabrics or as a base fabric for the production of coated fabrics.
• the invention is also based on a process for the production of fibers and threads by a wet or dry spinning process, the wet stretching of the spun threads being able to take place before, during or after the washing treatment, the threads then being dried and then subjected to hot stretching.
• the process according to the invention is characterized in that the threads are optionally dried in cable or strand form on hot rollers under tension and then subjected to a contact stretching of at least 1: 1.5, the effective total stretching having to be at least 1: 9.
• the stretching in the dry hot state should be e.g. be understood by using panel radiators.
• the threads are fixed by exposure to dry heat. This can be done, for example, on rotating hot rollers, on irons, in a hot air duct or by infrared radiation.
• the precipitation or solution polymers prepared by the customary processes can be used as polymer raw materials. Depending on the requirements for the areas of application, both homo- and copolymers of acrylonitrile can be used. The purity of the monomers used should be as high as possible. Suitable comonomers are all unsaturated compounds copolymerizable with acrylonitrile.
• Polymers can be used whose relative solution viscosities - measured in 0.5% dimethylformamide solutions - are in the range from 2.5 to 6.0. Particularly good results under economic conditions are achieved with polymers which are in a viscosity range from about 2.6 to 3.5.
• the polymers used should preferably have a content of at least about 99% by weight of acrylonitrile units.
• the dissolving conditions are to be selected so that the most homogeneous, gel particle-free spinning solutions are obtained.
• Scattered light measurements using a laser as the light source are particularly suitable for checking the quality of the spinning solution. Only flawless spinning solutions which show very low scattered light values enable the high draws required according to the invention.
• the spinning solutions can be prepared both continuously and discontinuously.
• Inorganic or organic additives can be incorporated into the spinning solution, e.g. Matting agents, stabilizers, flame retardants, etc.
• the spinning process according to the invention is characterized by a high effective total drawing of at least 1: 9.
• the effective total drawing should be at least 1: 9 by the method according to the invention. Effective total draw ratios of 1:10 to 1:25 are preferred.
• the method according to the invention can be carried out on conventional thread or fiber spinning systems. New techniques that were not previously common are not required. In particular, it is not necessary to use a special drawing chamber in which the threads, for example in the form of cables, are exposed to the action of steam under pressure. will.
• the process is characterized by high total draw values of the freshly spun threads, whereby an effective minimum draw of 900% is required. This effective total drawing takes place in several stages.
• the threads are stretched wet before or after washing out the residual solvent content in one or gradually in several hot baths.
• the temperature of the stretching bath media which usually consist of mixtures of water and the solvent, should be kept as high as possible. Temperatures a little below the boiling point of the bath liquid are preferred.
• baths which contain other stretching bath media, for example glycol or glycerol, if appropriate in a mixture with the polymer solvent, in which stretching temperatures above 100 ° C. can also be selected.
• the threads are prepared in a preparation bath and then freed as much as possible of adhering water by the action of rotating pairs of press rollers.
• the preparation applied in the preparation bath can influence the stretching behavior of the threads. It should therefore be selected from known preparation mixtures that shows a low thread-thread friction.
• the threads are then dried under tension on hot rollers.
• a small amount of shrinkage which often proves to be advantageous for the subsequent stretching, can be permitted during drying;
• care must be taken that the cables always run under tension over the drying rollers.
• the temperature of the rollers should be selected so that the cable leaves the dryer with a very low residual moisture content of less than 1%. Temperatures in the range from 140 to 200 ° C. have proven particularly favorable for these rolls, but this does not exclude the application of higher or lower temperatures. It is also possible to dry on the rollers at stepped temperatures.
• the spun tow is stretched again using dry heat at least 1.5 times its length.
• the stretching can also take place in one or more stages.
• the heating of the cable can be carried out according to the methods customary in the art, e.g. by rotating hot rollers, by contact over hot plates, in a hot air duct or by radiation, in particular infrared radiation. Gradual stretching, in which different heating methods are used, can also be used.
• the drawing temperatures are influenced by the type of polymer used and in part by the previous drawing and the drying conditions.
• a temperature range of about 120 to 250 ° C. is generally suitable, and the range of 140 to 200 ° C. is particularly favorable.
• the threads are fixed by the action of dry heat at temperatures of 170 to 280, preferably 180 to 250 ° C without allowing shrinkage.
• the fixation can be carried out according to the methods customary in the art, e.g. by rotating hot rollers, by contact with hot plates, in a hot air duct or by radiation, in particular by infrared radiation.
• the threads are cooled, either wound into continuous material by known methods or cut into fibers with the desired cutting length. If required by the area of application, can or a special preparation can be applied to the threads or fibers after cutting.
• the selection of the temperatures and the dwell time of the threads during fixing can have a significant influence on the physical properties of the treated in this way. Threads and their resistance to swelling and / or hydrolytically active substances.
• the optimal conditions in individual cases can, however, be determined by simple tests. They are influenced, for example, by the titer of the individual filaments, the total thread thickness, the quality of the contact with the heated surfaces, etc. Under the conditions of Example 4, optimal values at temperatures of the 1st duo of 190 ° C. and 230 to 250 ° C. for the 2nd duo and residence times of in total approx. 40 seconds were observed on the surfaces of the rolls.
• a polymer of 99.4% acrylonitrile and 0.6% methyl acrylate was continuously dissolved in a 17% spinning solution in dimethylformamide, filtered and degassed.
• This spinning solution was 351 g / min through a nozzle with 2500 holes, hole diameter 0.06 mm; pressed into a precipitation bath which contained 56% dimethylformamide (DMF) and 44% water and was 50 ° C. warm.
• the filaments obtained were drawn off the nozzle at 6.5 m / min, drawn in baths containing 56% DMF and 44% water at 98 ° to six times their length and then washed. When washing in hot water, 9% shrinkage was allowed.
• the threads were dried at 165 ° C. and stretched in two stages at 180 ° C. to 2.4 times their length. The total draw was 1: 13.1.
• the fixed and, as a comparison, the unfixed fibers were each treated for 24 hours with a cement filtrate made from 150 g of Portland cement and 1 liter of water at different temperatures.
• the aqueous cement extract had a pH of approximately 11.6.
• the tested filaments were briefly rinsed with water and air-dried at room temperature. Force expansion diagrams were then recorded on the individual filaments at an elongation rate of 100% / min and the initial moduli were determined. During the treatment at 90 ° C the fixed fibers shrank by 3%, the unfixed ones by 12.5%.
• a polymer was spun according to Example 1, but consisting of 95% acrylonitrile and 5 * % acrylic acid methyl ester. With these threads, the stretching had to be reduced somewhat after drying, so that the total stretching was only 1: 11.7.
• the unfixed fibers had an initial modulus of 1340 cN / tex, those fixed at 230 ° C an initial modulus of 1020 cN / tex. After a 24-hour treatment at 90 ° C. in the Portland cement filtrate described, the unfixed fiber had an initial modulus of 720 cN / tex and the fixed one an initial modulus of 740 cN / tex. After this treatment, both fibers had a slightly sticky surface in the moist state, which suggests that the fibers had already been slightly saponified in the hot, alkaline medium.

Landscapes

• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Nonwoven Fabrics (AREA)
• Inorganic Fibers (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

Family

ID=4221620

Family Applications (1)

Country Status (13)

Cited By (7)

Families Citing this family (12)

Family Cites Families (11)

• 1981
  • 1981-03-20 CH CH1918/81A patent/CH647271A5/de not_active IP Right Cessation
• 1982
  • 1982-03-15 AT AT82102086T patent/ATE14757T1/de not_active IP Right Cessation
  • 1982-03-15 EP EP82102086A patent/EP0061117B1/fr not_active Expired
  • 1982-03-15 DE DE8282102086T patent/DE3265153D1/de not_active Expired
  • 1982-03-17 JP JP57040970A patent/JPS57161117A/ja active Pending
  • 1982-03-18 DD DD82238270A patent/DD202187A5/de not_active IP Right Cessation
  • 1982-03-18 US US06/359,233 patent/US4446206A/en not_active Expired - Fee Related
  • 1982-03-19 DK DK125282A patent/DK125282A/da not_active Application Discontinuation
  • 1982-03-19 NO NO820916A patent/NO156698C/no unknown
  • 1982-03-19 ZA ZA821849A patent/ZA821849B/xx unknown
  • 1982-03-19 BR BR8201530A patent/BR8201530A/pt unknown
  • 1982-03-19 CA CA000398839A patent/CA1171214A/fr not_active Expired
  • 1982-03-19 IL IL65294A patent/IL65294A/xx unknown
• 1983
  • 1983-12-07 US US06/558,956 patent/US4536363A/en not_active Expired - Fee Related

Also Published As

Similar Documents

Legal Events