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

Definitions

• This invention relates to acrylic fibers with high physical properties suitable as material for cement reinforcement, and to a method of industrial production of the same.
• Fibers for which high strength and high modulus of elasticity are required have a wide field of use, with the use as reinforcement material being of central importance.
• the object of this invention is to provide acrylic fibers with high physical properties suitable as material for cement reinforcement and a method of producing the same, without the above-mentioned problems.
• the acrylic fibers which make it possible to attain the object of this invention are composed of a polymer containing more than 80 weight % acrylonitrile (hereinafter referred to as AN) and have strength-elongation characteristics determined by the following formulas: (I) 8 ⁇ TS, (II) 140 ⁇ E, (III) TE ⁇ 15, and (IV) 1800 ⁇ E x TE, wherein TS represents tensile strength (g/d), E Young's modulus (g/d), and TE elongation (%).
• AN polymer containing more than 80 weight % acrylonitrile
• Such fibers can be produced in an industrially advantageous manner by spinning a spinning solution of the above-mentioned acrylonitrile polymer while maintaining the linear velocity ratio of extrusion (defined below) above 4, water-washing and stretching the extruded gel fibers, subjecting the fibers after stretching to dry-heat treatment under tension or dry-heat stretching at a temperature which permits the maximum stretching times ⁇ 30°C, then cooling the fibers under tension, thereby making the effective total stretching times more than 15 times.
• Linear velocity ratio of extrusion wherein V o is a linear velocity of extrusion of the spinning solution (m/min), and V is a winding velocity of the extruded gel fibers (m/min).
• AN polymer used in this invention a polymer insofar as it contains more than 80 weight %, preferably more than 90 weight % of AN, can be used without limitation in its molecular weight, etc.
• the other components there may be mentioned known monomers that can be copolymerized with AN, for example such as methyl, ethyl, butyl, octyl, methoxyethyl, phenyl, cyclohexyl, etc.
• esters of (meth)acrylic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, etc.; (meth)acrylamide and derivatives thereof; unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid, itaconic acid, etc.
• unsaturated sulfonic acids such as vinylsulfonic acid, (meth)allylsulfonic acid, p-styrenesulfonic acid, acrylamide propanesulfonic acid, and salts thereof
• vinyl halides and vinylidene halides such as vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene fluoride, etc.
• vinyl compounds such as styrene, ethyl vinyl ketone, methyl vinyl ether, (meth)allylalcohol, vinyl pyridine, dimethyl aminoethyl methacrylate, vinylidene cyanide, methacrylo­nitrile, glycidyl (meth)acrylate, etc.
• organic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, etc.
• aqueous solutions of inorganic solvents including thiocyanates such as sodium thiocyanate, potassium thiocyanate, ammonium thiocyanate, etc. and nitric acid, zinc chloride, etc.
• the polymer concentration there is no limitation on the polymer concentration, but from the industrial viewpoint, it is desirable to determine it generally at 5-30 weight %, preferably at 7-15 weight %.
• the ratio is important to conduct spinning while maintaining the linear volocity ratio of extrusion of the spinning solution at above 4, desirably between 5 and 20, and more desirably between 6 and 12.
• the ratio is out of the lower limit of this range, the stretchability lowers, and if the fibers are not subjected to a special stretching operation such as multistage stretching in a high-boiling-point medium above 100°C, it is impossible for the fibers to attain the necessary effective total stretching times and the finally obtained fibers show only inferior physical properties.
• the ratio goes out of the upper limit of the range, there occur problems such that the use of a deep coagulation bath is necessary, or the physical properties become uneven.
• extruded gel filaments drawn out of the coagulation bath are then washed with water and stretched.
• the filaments may be cold-stretched and heat-stretched during water-washing (solvent removal) in the usual way or after water washing.
• Each of the cold and heat stretchings may be conducted in multistage steps.
• the water content of the gel filaments immediately after such stretching steps is desirably determined within the range of from 50 to 150%, preferably from 55 to 130%.
• the means of controlling the water content include the regulation of the polymer concentration in the spinning solution, the temperatures of the coagulation bath, water-washing and stretching.
• the stretching times in the above-mentioned cold and heat-stretching steps at more than 10 times, preferably from 12 to 20 times while taking into account the above-mentioned linear velocity ratio of extrusion, the water content can be controlled advantageously and finally the fibers with high physical properties can be provided in an industrially advantageous manner.
• by apportioning the cold stretching times and heat stretching times as follows more desirable results can be obtained: wherein A represents cold stretching times and B heat stretching times.
• the filaments thus obtained by spinning, water-washing and stretching may be sent to the succeeding step while maintaining the above-mentioned water content. But it is particularly desirable from the viewpoint of operation to regulate the internal water content of the gel filaments just after stretching to within the range of from 2 to 20%, preferably from 5 to 15% and thereafter to subject the filaments to dry heat treatment under tension or to dry heat stretching.
• the gel filaments after the heat stretching are dried on heated rolls under tension (with limited shrinkage, preferably in a definite length) successively or under a certain degree of stretching (less than about 1.2 times) so as to regulate the internal water content of the gel filaments to within the prescribed range.
• the temperature of the heated rolls is desirably set at below about 140°C. preferably withing the range of from 60 to 120°C, and for the best, from 70 to 100°C.
• the temperature condition is particularly important. It is necessary to set such temperature within the range of the temperature making possible the maximum stretching ⁇ 30°C, preferably ⁇ 20°C.
• the temperature making possible the maximum stretching means the temperature at which the maximum stretching times can be obtained without causing filament breakage in the dry heat stretching step.
• the filament can manifest the high physical properties which have been given to the filaments in the previous steps. When the temperature is out of this range, it is impossible to produce the fibers of this invention.
• the filaments under tension it is important to cool the filaments under tension subsequently.
• a tension condition it is desirable to stretch more than 1.02 times, preferably 1.05 times so that the filaments after dry heat treatment under tension or dry heat stretching may not be relaxed and lowered in physical properties while they are cooled to room temperature, or may not be wound around the rollers. If the filaments are heat-set after dry heat stretching and before cooling under tension, the physical properties can be further improved.
• the recommended heat-set condition is dry heat between 180° and 250°C, preferably under a definite length.
• acrylic fibers produced in the above-mentioned steps under the above-mentioned condition it is necessary to determine a stretching condition so that the effective total stretching times should be finally above 15 times, preferably above 18 times, and for the best, above 20 times.
• the temperature making possible the maximum stretching varies greatly depending on the polymer composition, polymer molecular weight, spinning condition, etc., so that it is impossible to fix it definitely.
• the temperature generally varies within the range of from 140° to 180°C.
• the precise value of such a temperature is obtained as follows: For example, the dry heat stretching temperature for the sample fibers is gradually changed and the stretching times for each temperature at which the fibers are broken are obtained. Thus the dry heat stretching temperature giving the maximum stretching times can be obtained.
• acrylic fibers having strength-elongation characteristics of a tensile strength (TS) generally above 8 g/d, preferably above 10 g/d, a Young's modulus (E) above 140 g/d, preferably above 150 g/d, an elongation (TE) less than 15%, preferably less than 12%, and a product of Young's modulus and elongation (E x TE) above 1800.
• TS tensile strength
• E Young's modulus
• TE elongation
• E x TE product of Young's modulus and elongation
• the solvent removal and coagulation speed due to the spinning under the condition of the linear velocity ratio of extrusion recommended in this invention can bring the polymer molecular structure in the extruded gel filaments to such a state in which excellent stretching and orientation can be obtained in the following stretching step.
• the succeeding water-washing and stretching and the subsequent dry heat treatment under tension or dry heat stretching under a particular temperature condition as well as the cooling which comes next aid in bringing the molecular chains of the finally formed filaments into parallel arrangement near the "stretched-­to-the-full-length" chains, without forming voids in the fiber structure.
• the high physical properties can be manifested.
• the acrylic fibers of this invention retain a moderate elongation contrary to common knowledge, and have a high strength and modulus of elasticity. Therefore, when the fibers are used, for example, as a cement reinforcement material, the fibers can withstand the stress such as shear and bend upon dispersion, molding or shrinkage of cement. Also, the fibers can minimize the cracks generated during the use of the cement reinforced with the fibers, thus improving the tenacity. Moreover, the fibers of the invention have an advantage of elevating the impact strength of the reinforced cement.
• the acrylic fibers of this invention can be widely used in the industrial use field including reinforcment materials for resin and cement, tire cords, precursors for carbon fibers, ropes, etc. Therefore, the usefulness of the fibers of this invention is very large.
• the spinning solution at 80°C was extruded into an aqueous 15% sodium cyanate solution at -3°C through a spinnerette (50 orifices, diameter of each orifice: 0.05 mm), and the resulting filaments were wound at various linear velocity ratios of extrusion, as described in Table 1.
• the filaments were then cold-stretched 3.0 times and thereafter heat-stretched in boiling water, thereby to obtain the maximum heat-stretching times.
• Water-swollen gel filaments (internal water content:73%) were produced in the same way as in Referential Example 1 No. 5 except that the heat-stretching times were 5.3 times.
• sample fibers were dried under a definite length on heated rolls of 80°C so that the internal water content could become 10%, and the fibers were heat-stretched at various temperatures of the heated rolls, as described in Table 2. Thus the maximum stretching times (dry-heat stretching times at breakage) at each temperature was obtained.
• the fibers of this invention have excellent physical properties, and that when the dry-heat stretching temperature goes out of the range of this invention (Fiber F,and Fiber E cooled without tension), it was impossible to obtain fibers with high modulus of elasticity and high elongation.
• Example 1 Fiber C except that the linear velocity ratio of extrusion was varied as shown in Table 4, three kinds of fibers (G, H, and I) were produced. The internal water content and physical properties were measured. The results are shown in Table 4.
• Fibers J and K were produced in the same way as Example 1 Fiber D except that the molecular weight of the AN copolymer was changed to ( ⁇ ):1.8, or the composition was changed to 97% AN and 3% MA, and that, as the dry-heat stretching temperature, temperatures allowing the maximum stretching shown in Table 5 were employed.

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• Health & Medical Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)

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• 1985
  • 1985-08-05 JP JP17268285A patent/JPS6233817A/ja active Pending
• 1986
  • 1986-08-04 EP EP19860305986 patent/EP0213772B1/de not_active Revoked
  • 1986-08-04 DE DE8686305986T patent/DE3670312D1/de not_active Revoked

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