KR920002839A - Method for producing unspun high orientation acrylic short fibers - Google Patents

Abstract

No content.

Description

Method for producing unspun high orientation acrylic short fibers

As this is a public information case, the full text was not included.

FIG. 1A shows a typical melt endothermic peak and a solidification exothermic peak by differential scanning calorimetry (DSC) of an acrylonitrile polymer water content, wherein the molten quasicrystalline phase having molecular order between the melting temperature (Tm) and the solidification temperature (Tc) The temperature range OR can be formed.

FIG. 1b shows, as an example of FIG. 1a, a melt endothermic peak and a solidified exothermic peak of a water-containing water in which 20% of water is mixed with an acrylonitrile polymer containing 89.2% of acrylonitrile and 10.8% of methyl acrylate in weight ratio.

FIG. 2a shows a typical change of the melting temperature and the solidification temperature according to the water content in the water content of the acrylonitrile polymer, and shows a temperature range in which a molten quasi-crystalline phase having a molecular order similar to that of liquid crystal can be formed. have.

FIG. 2B shows a change in the melting temperature and the solidification temperature depending on the water content in the hydrate of the acrylonitrile polymer containing 89.2% acrylonitrile and 10.8% methyl acrylate in weight ratio as an example of FIG. 2A.

3 shows the change of the melting temperature and the solidification temperature according to the content of methyl acrylate, which is a copolymerization monomer, in the water of acrylonitrile polymer, and the acrylonitrile polymer is increased as the methyl acrylate content is increased in the acrylonitrile polymer. It shows that the melting temperature and the solidification temperature of the water are lowered.

Figure 4 shows the orientation of the extrudate according to the temperature of the melt when extruding the melt of the acrylonitrile polymer water content, the orientation degree is almost unoriented at about 50% in the temperature range to form an amorphous melt In the temperature range for forming the molten quasi-crystalline phase, it indicates that the orientation is also high molecular orientation of 80% or more.

Figure 5a is a structural model in which the acrylonitrile polymer chain forms a three-dimensional molecular order by interaction with water molecules when the semicrystalline phase of the acrylonitrile polymer hydrate is extruded in the molten state.

FIG. 5b shows structural models in which acrylonitrile polymer chains form a plate feed reel of linear chains when fibers are formed after extrusion solidification. The polymer chains extend in the direction of ＂C＂ at the arrow and ＂V＂ at the arrow. Weak van der Waals force in the direction and the hydrogen bonding force on the molten semi-crystalline phase in the ＂H＂ direction during the formation of the fiber shrinks as water escapes during fiber formation It is indicated that the dipole attraction between the nitrile groups acts in the ＂D＂ direction at the arrow instead of the hydrogen bonding force after formation.

FIG. 6 is a scanning electron microscope photograph of the cross section and the longitudinal section of the tape-like extrudate obtained by extruding the molten semi-crystalline phase and the fibers are formed. The cross-sectional fibrils are neatly stacked in the cross section with the space where the water escapes. In the cross-sectional structure and longitudinal section, each fibrils are separated into microfibrils again to form an internal structure forming a fiber.

FIG. 7 illustrates the cross-sectional and longitudinal cross-sectional structure of the tape-shaped extrudate of FIG. 6, wherein the plate-shaped fibrils are stacked in the cross-sectional structure and the longitudinal cross-sections of the tapered extrudate are arranged in the cross-section. It shows an internal structure composed of many microfibrils and indicates that fibrils and microfibrils can be easily separated into individual fibers.

FIG. 8 is an X-ray diffraction pattern photograph of the tape-like extrudate of FIG. 6, showing that the fibrous crystal structure and the highly oriented structure are formed.

FIG. 9 is a diffraction intensity curve scanned in the azimuth direction at the position of the main diffraction peak (2θ = 16.2 °) in the equator direction on the X-ray diffraction pattern of FIG. 8, and it can be seen that high molecular orientation is achieved.

FIG. 10 is a scanning electron microscope photograph of pulp-like short fibers obtained by cutting a heat-extruded tape-like extrudate to an appropriate length and beating it. Each fiber is composed of fibrils and microfibrils. It shows that it has many cracks and branches in irregular cross sections and sides.

Claims (14)

A mixture of acrylonitrile homopolymer or copolymer having a viscosity average molecular weight of 10,000 to 600,000 and having a weight average of 70% or more and acrylonitrile of 70% or more, and mixing water of 5% to 100% by weight The mixture is heated under the seal to above the melting temperature to form an amorphous melt, which is cooled below the melting temperature to obtain a supercooled melt phase, which is then extruded through a straight extrusion port into the external environment at a temperature between the melting temperature and the solidification temperature Obtained extrudate exhibiting a fibrous crystal structure and orientation of 70% or more in an x-ray diffraction pattern having a cross-sectional structure in which plate-like fibrils formed by solidification while being automatically removed by water are arranged in an x-ray diffraction pattern. Tensile forces are applied between the maintained hot gas atmosphere or between the hot compression rollers. After stretching and heat-treating in a state, it is characterized by mechanically beating the pulp-like short fibers of the highly oriented fibril structure having a distribution between 0.1 μm and 100 μm in thickness and a distribution between 0.1 mm and 100 mm in length. How to manufacture. The method of claim 1, wherein the highly oriented fibrillated structure is formed of microfibrils between 0.01 μm and 1.0 μm thick and plate-like fibrils between 1 μm and 10 μm thick, and exhibits a fibrous crystal structure and orientation of 70% or more. A method for producing pulp-like short fibers. The method for producing pulp-like short fibers according to claim 1, wherein the plate-like fibrils have a thickness of between 1 μm and 10 μm, which in turn consist of a number of microfibrils between 0.01 μm and 1.0 μm thick. The method for producing pulp-like short fibers according to claim 1, wherein the stretching heat treatment is performed between 120 ° C and 200 ° C. The method for producing pulp-like short fibers according to claim 1, wherein the stretching heat treatment involves stretching of 5% to 100%. The method for producing pulp-like short fibers according to claim 1, wherein the hot gas atmosphere is made of a gas which hardly undergoes chemical reaction with an acrylonitrile polymer such as water vapor, air, nitrogen, argon, and the like. The pressure of 5 atm or less according to claim 1, wherein the external environment is less than 100 ° C., a gas of 5 atm or less, or a natural vapor pressure atmosphere of 100 to 150 ° C., or a vertical tube filled with a molten alloy having a melting point of less than 100 ° C. A method for producing pulp-like short fibers, which is in an applied state. The method for producing pulp-like short fibers according to claim 1 or 7, wherein the external environment is at room temperature, atmospheric pressure, and air atmosphere. The method for producing pulp-like short fibers according to claim 1, wherein the supercooled melt phase is formed between the melting temperature and the solidification temperature of the polymer water content. The method of claim 1, wherein the mixture comprises between 10% and 50% water by weight relative to the polymer. The method for producing pulp-like short fibers according to claim 1, wherein the amorphous melt is made in a temperature range of not less than the melting temperature of the polymer water to 220 ° C. The acrylonitrile homopolymer or airborne copolymer of claim 1, wherein the microfibrils and the plate-like fibrils are composed of acrylonitrile having a weight ratio of 70% or more and copolymerizable monomers of 30% or less, and have a viscosity average molecular weight of 10,000 to 600,000. Method for producing pulp-like short fibers, characterized in that composed of coalescence. The method for producing pulp-like short fibers according to claim 1 or 12, wherein the viscosity average molecular weight of the acrylonitrile homopolymer and copolymer is between 50,000 and 350,000. The method for producing pulp-like short fibers according to claim 1 or 12, wherein the acrylonitrile homopolymer and the copolymer are composed of acrylonitrile with a weight ratio of 85% or more and a copolymerizable monomer with a weight ratio of 15% or less. ※ Note: The disclosure is based on the initial application.