JPS62282015A - High strength and high modulus polyvinyl alcohol fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Background of the Invention Field of the Invention The present invention relates to the production of polyvinyl alcohol fibers having high molecular weight, strong tinacity and tensile modulus, and gel fibers by extruding a dilute solution. The present invention relates to a method for producing the same polyvinyl alcohol fibers by forming and subsequently drawing the fibers.

Conventional technology Zwick etc. go c, Chem, I
nd.

London, Monograph A30, 1188-207
Page (1,968) describes the spinning of polyvinyl alcohol by a phase separation method which is said to be different from the conventional wet spinning method, dry spinning method and gel spinning method. This document states that in conventional systems, the polymer concentration is 10 to 10, respectively.
This indicates a difference of 20%, 25-40%.

This document points out that certain conventional systems limit the spinneret pore size, the attenuation allowed or required, the maximum production speed, and the fiber properties that can be achieved.

The phase separation method described in Zwick et al. (see also British Patent No. 1.1.00,497) uses one-component or two-component bath additives (low molecular weight components) that undergo phase separation on cooling. The system employs a polymer content of 10-25% at elevated temperatures (in the British patent cited above, the polymer content ranges broadly from 5-25%, and other polymers are included as well). This phase separation took the form of gelation of the polymer and coagulation of the solvent (or one of its components). However, the British patent points out that the latter is optional. The method involved forcing the solution through the holes at high temperatures, passing unheated air through it, and winding it up at high speeds hundreds to thousands of times greater than the linear velocity at which the polymer solution was drawn from the holes.

The fibers were then extracted to remove the absorbed or outer surface coolant phase, dried, and stretched. A conventional and more general explanation of phase separation spinning is given by Zwick's Appli
ed Polymer Symposia, 166,
109-149 (1967).

Improvements in hot solution spinning of ultra-high molecular weight polyethylene (see Examples 21-23 of British Patent No. 1,100,497) were made by Smith and Lemstrα and by Pennings.
? German Patent Publication No. 3004699 (August 21, 1980) by L. Nings and co-workers;
British Patent Application No. 2,051,667 vol.1
, pp. 879-88o (1979) and vol. 2
．． pp. 775-83 (1,980); and Poly
Mer, 2584 90 (1980). Co-pending U.S. Patent Application No. 359,019 and U.S. Pat.
, filed March 19, 982) describes a process involving extrusion of a dilute hot solution of ultra-high molecular weight polyethylene or polypropylene in a non-volatile bath, followed by cooling, extraction, drying and stretching. Although US patent application Ser. No. 1 J359,019 states that certain other polymers in addition to polyethylene or polypropylene are also useful, it does not include polyvinyl alcohol or similar polymers.

British Patent No. 1,100,497 indicates that molecular weight is a factor in selecting the optimum polymer concentration (page 3, lines 16-26), but higher molecular weights are improved for polyvinyl alcohol. There is no disclosure of providing fiber. Zwick's miscellaneous text in Applied Polymer Synosiα describes the optimum polymer concentration of 20% for textile grade polyvinyl alcohol.
Although the polymer concentration is set at ~25%, the polymer concentration for polyethylene is arbitrary and may be as high as 3%. The report by Zwick et al. or the system in which the solvent or its components solidify on cooling so that the polyvinyl alcohol concentrates in the liquid phase when cooled before the polyvinyl alcohol gels has been investigated in the most detail, At least in that system, it is stated that the optimum polyvinyl alcohol content in the polymer concentration is 10-25%. Unlike the systems used in the aforementioned U.S. patent applications of Kabetsch et al. and the aforementioned patents of Smith and Lemstra, Sowick's phase separation method 3
All three variants draw the fibers directly from the air gap without a cooling bath so that the fiber draw-off occurs over a relatively long length of the cooling fiber.

U.S. Pat. No. 4,440,711 has a weight average molecular weight of at least approximately 500,000 and at least about 10
77 denier Tina City, at least about 200
? /denier tensile modulus and at least 238°
Concerning polyvinyl 7 #-y-le fibers having a bath melting temperature of C. Other patents disclosing polyvinyl alcohol fibers are JP-A-60=126311 and JP-A No. 60-1.
2631.2, 59-100710 and 6
No. 0-126322, European Patent No. 0146084 and US Pat. No. 3,757,547.

SUMMARY OF THE INVENTION The present invention provides (al) having a weight average molecular weight of about 100,000 to about 50
A solution of 0.000 legged polyvinyl alcohol in a first solvent having a first polyvinyl alcohol concentration of from about 5% to about 35% by weight is prepared, and the first extruding the solution at one concentration and at a temperature equal to or higher than a first temperature upstream of the extrusion hole from the extrusion hole; to a second temperature below the temperature at which a rubbery gel is formed to form a first solvent-containing gel of substantially infinite length; , a contact time sufficient to form a second solvent-containing fibrous structure, the structure being of substantially infinite length and substantially free of the first solvent; and Ie) drying the second solvent-containing fibrous structure to form a substantially infinite length xerogel free of first and second bath agents; (ii) the second solvent-containing fibrous structure and (ii) at least one of the xerogels;
the v/denier at a heating rate of about 10° C./min by scanning calorimetry at a heating rate of about 10° C./min. The method includes a method of making polyvinyl alcohol fibers that exhibit single or multiple endotherms, at least one of which when measured is at a temperature equal to or greater than about 246°C.

The present invention also provides compounds having a weight average molecular weight of about 100,000 to about 5
00,000, a tinacity of at least about 91/denier and a tensile modulus of at least about 200 f/
Denier, and original scanning calorimetry) IJ- about 1
The present invention includes novel oriented polyvinyl alcohol fibers that exhibit single or multiple endotherms with at least one of the endotherms being at a temperature equal to or greater than about 246° C. when measured at a heating rate of 0'c/min. The results obtained by the present invention are indeed surprising in that it was previously thought that polyvinyl alcohol fibers with excellent tensile properties could only be obtained with polyvinyl alcohols having a molecular weight of at least about 500,000. be. However, experiments show that the molecular weight is approximately 1. The tensile properties of fibers made from polyvinyl alcohol with O'<0.000 have proven to be poor in fact, whereas fibers composed of polyvinyl alcohol with molecular weights from 1.00,000 to about 500,000 have superior tensile properties. The results show that.

Furthermore, the fibers of the present invention are inherently water-insoluble and require no additional treatment, such as treatment with formaldehyde, borax, or similar compounds, and are soluble in water at elevated temperatures or after prolonged immersion. However, it retains its tensile properties well. The fibers of the present invention have excellent dimensional stability and have low creep under load and shrinkage at elevated temperatures.

Such excellent wet and dry tensile properties and dimensional stability are the result of the fiber's novel structure.

The polyvinyl alcohol fibers of the present invention have a relatively high degree of crystal orientation as measured by wide-angle X-ray diffraction (crystalline orienta -
tion function ] fc is approximately 0995
thicker).

The non-inventive fibers exhibit single or multiple melting endotherms, or melting peaks, when measured by differential scanning calorimetry at a heating rate of 10"C/min, distinct from conventional fibers of the same or lower molecular weight. at least one of the bath melt peaks is at a temperature of at least about 246°C. This fiber melting temperature is typically at least about 10° to about 15"C higher than the polymer from which the fiber is made, which is due to the fact that the molecules in the fiber This is thought to be a reflection of the extremely high degree of orientation.

DETAILED DESCRIPTION OF THE INVENTION The methods and fibers of the present invention are described in more detail below.
). With this ultra-high molecular weight polyvinyl alcohol, wet spinning, dry spinning, gel spinning, or phase separation spinning methods are all described in the above-mentioned miscellaneous papers of Zwick, miscellaneous papers of Zwick et al., and British Patent No. 1.1.00゜497. Extrusion of dilute solutions at lower concentrations than those used in the present invention allows the production of PV-OH fibers (and films) with properties not previously available. Additionally, preferred solvents of the present invention phase separate from the PV-OH upon cooling to form non-PV-01
occ'1Qed phase
), and rather forms a highly homogeneous dispersion gel, which is different from gels formed by phase separation methods. The ability to process such gels, which are formed by extrusion and cooling of dilute solutions, requires the use of higher solids contents to extrude the polymer and concentrate the fibers in the form of a thick, tough gel without prior removal of the solvent. This differs from the conventional gel spinning method of PV-OH, such as by spinning, which requires a spinning dope (40-55 inches).

The PV-OH polymer used is leg-shaped and has a weight average molecular weight of approximately 1.
00,000 to about 500,000. In a clever embodiment of the invention, the weight average molecular weight is about 200,
000 to about 450,000, and in particularly preferred embodiments from about 300,000 to about 450,000. The weight average molecular weight of PV-OR can be measured by either a direct method or an indirect method, but the indirect method is most convenient.

Both methods use narrow angle laser source scattering (LALS). Commercially available LALS device (LDC/Milton Roy [Mi
Chromatics [C
chromatiz]KMX-6) can be used. For the direct method, PV-OH is dissolved in diethylenetriamine. However, in the case of diethylenetriamine, PV-OH
Change in concentration (d?L/d c= 0.0521nl/
? ) The change in refractive index is very small. In addition to this, the solvent is corrosive and the solution is very viscous and difficult to filter. The indirect method is more accurate than the direct method, which measures polyvinyl acetate (FT'Ac) obtained by acetylation of PV-OH.

A solution prepared by dissolving this PTIA c in methanol has extremely good optical properties (dn/d c -
Q. 11ml/? ), and it is very easy to filter.

Measurements of A(w made for PVAc can be calibrated for monomer weight differences to yield Mw for PV-OH.

The term "pediculate" means that there is only minimal branching of the α- or β-type. Polyacetic acid e-vinyl (
Since the most common branching that occurs during the production of PVAc) is in the acetate side chain, such branching creates a side group that cleaves to PV-OH during hydrolysis or metatrilysis, and PV- with smaller dimensions rather than increased branches
OH is generated.

The total amount of branching can be measured most accurately using nuclear magnetic resonance or magnetic resonance. A fully hydrolyzed material (pure PV-OH) is preferred, but copolymers with some residual vinyl acetate may also be used. Such leg-like ultra-high molecular weight PV-OH is described in commonly assigned U.S. Pat. It can be produced by photoinitiated polymerization of vinyl acetate at low temperature followed by metatolysis using a method.

The first solvent must be non-volatile under the processing conditions. This property maintains an essentially constant bath agent concentration upstream of and through the extrusion hole, and prevents non-uniform liquid content of the gel fiber or film containing the first solvent. It is necessary to prevent The vapor pressure of the first bath agent is preferably about 180° C. or less than 80 kPa (atmospheric pressure) at the first temperature. Preferred first solvents for PV-OH include aliphatic and aromatic alcohols with the desired non-volatility and polymer solubility.

The boiling point at 101 kPa is about 150° to about 300°C
Hydrocarbon polyols and alkylene ether polyols are preferred, such as ethylene glycol, propylene glycol, glyceptol, diethylene glycol and triethylene glycol.

Water and aqueous or alcoholic solutions of various salts such as lithium chloride, calcium chloride, or other substances capable of breaking hydrogen bonds and increasing the solubility of pv-OH are also well suited. The polymer can be present in the first bath agent at a first concentration. The first concentration is selected from a relatively narrow range, e.g., from about 5 to about 35% by weight, but once selected, the concentration will be at a location adjacent to the die or elsewhere before being cooled to a second temperature. It should not change depending on location. The concentration of polymer varies inversely with its molecular weight. For example, about 100,000 to about 300,000
When using a polymer having a molecular weight of 0.000, the concentration preferably varies from about 10 to about 35 parts by weight, approximately 30% by weight.
When using polymers having a molecular weight of from 0.000.000 to about 500.000, the concentration preferably varies from about 5 to about 20 parts by weight. The concentration should remain fairly constant over time (ie, fiber or film length).

The first temperature is selected such that the polymer is completely dissolved in the first solvent. The first temperature is the lowest temperature at any point between where the solution is formed and the die face, but must be higher than the gelation temperature of the polymer in the solvent at the first concentration. For glycerin PV-OH at a concentration of about 5 to about 5%, the gelation temperature is approximately about 25 to 100°C;
Therefore, a preferred first temperature is 130° to 250°C, more preferably about 170 to 230°C. The temperature may vary above the first temperature at various points upstream of the goo surface, but excessively high temperatures that would degrade the polymer should be avoided. To ensure complete dissolution, the first temperature is chosen such that the solubility of the polymer exceeds the first concentration, typically at least about 20% higher.

The second temperature is chosen at which the first solvent-polymer system behaves as a gel, ie has a yield point and dimensional stability that allows subsequent handling. Cooling of the extruded polymer solution from the first temperature to the second temperature is accomplished at a sufficiently rapid rate such that gel fibers are formed in which the polymer concentration is substantially the same as the concentration in the polymer solution. Should. Preferably, the rate of cooling the extruded polymer solution from the first temperature to the second temperature is at least about 50°C/min.

A preferred method of rapid cooling to a second temperature is to use a quench bath containing a liquid such as a hydrocarbon (e.g., paraffin oil), and the extruded polymer solution is exposed to an air gap (which may be an inert gas). take a bath after passing through (can be done). It is also contemplated to combine the quenching step with the subsequent extraction by using a second bath agent (eg, methanol) as the quenching liquid. Usually, however, the quench liquid (eg, paraffin oil) and the first bath agent (eg, glycerol) have only limited miscibility.

Although it is not excluded from the invention that some stretching may take place during cooling at the second temperature 1, the total stretching ratio at this stage should generally not exceed 10:. As a result of these factors, the gel fibers formed upon cooling to the second temperature consist of a continuous polymer network highly swollen with the bath agent.

When using an extrusion hole with a circular cross section, or other cross-sectional shapes in which the major axis of a plane perpendicular to the flow direction is less than about 8 times the smallest axis of the same plane, such as an oval, Y-shaped or X-shaped extrusion hole, both gels together constitute gel fibers, the xerogel constitutes xerogel fibers, and the thermoplastic article constitutes fibers. Although the diameter of the pores is not critical, typical pore diameters (or other major axes) are from about 0.5 mm to about 5 mm. The length of the pore in the flow direction should be at least about 10 times the normal pore diameter (other similar long axis), preferably at least about 1
5 times, more preferably at least about 20 times.

With holes of rectangular cross section, both gels constitute a gel film layer, the xerogel constitutes a xerogel film, and the thermoplastic article constitutes a film. The width and height of the pore cross-section are not critical; for typical pores, the width (corresponding to the width of the film) is from about 2.5 mrR to about 2 m;
Corresponding to the thickness of the multi-layered film) is approximately 0.25 mtn
~about 5 mm. The depth of the pores (in the machine direction) should normally be at least about 10 times the pore height, preferably at least about 15 times, and more preferably at least about 20 times.

Extraction with the second bath agent is carried out in such a way that the -m-th agent in the gel is replaced with a second or more volatile solvent. When the first bath agent is glycerin or ethylene glycol, suitable second bath agents include methanol, ethanol, ethers, acetone,
Mention may be made of ketones and dioxane. Water is also a suitable second solvent for the extraction of glycerol (and similar polyol-based first solvents) or for the leaching of aqueous salt solutions as a first bath agent. The most preferred second solvent is methanol (E, P, 64.7°C). Preferred second bath agents are volatile solvents having an atmospheric boiling point of about 80°C or less, more preferably about 70°C or less.

Extraction conditions should be such that approximately 1% of the total solvent in the gel is removed from the first bath agent.

In the present invention, for certain first bath agents such as water or ethylene glycol, the solvent may be evaporated from the gel near the boiling point of the first bath instead of or prior to extraction. intended.

A preferred combination of conditions is a first temperature of about 130° to about 2
50°C, a second temperature of about 0°C to about 50°C, and a cooling rate between the first temperature and the second temperature of at least about 10°C/min. Preferably, the first bath agent is an alcohol. The first solvent must be substantially non-volatile, one measure of which is that its vapor pressure at the first temperature is approximately 475 atmospheres (80 kPa).
preferably less than about 10 kPa. When selecting the first and second solvents, the primary difference desired relates to volatility as discussed above.

Once the fibrous structure containing the second solvent is formed, it is then dried under sieve conditions to remove the second solvent and leave behind a solid network of substantially the polymer itself. By analogy with silica gel, the resulting material is referred to herein as 1xerogel, meaning a solid mal-IJ lux corresponding to the solid matrix of a wet gel; The term "paxerogel" does not describe any particular type of surface area, porosity or pore size.

When comparing the xerogels of the present invention with corresponding dry gel fibers produced by phase separation spinning, several morphological differences appear to be apparent.

Stretching can be performed on the gel fibers after cooling at the second temperature 1, or during or after extraction. Alternatively, the xerogel fibers may be drawn, or a combination of gel drawing and xerogel drawing may be performed. Stretching may be carried out in one step, or may be carried out in two or more steps. The first stage of stretching can be carried out at room temperature or at elevated temperature. Preferably, the stretching is carried out in two or more stages, the last of each of which is carried out at a temperature of about 120° to about 275°C.

Most preferably, the stretching is carried out in at least three stages, the final stage being carried out at a temperature of about 150° to about 260°C.

Such temperatures can be achieved by heated tubes as shown in the accompanying drawings, or by other heating means such as heating blocks or steam jets.

The PV-OH fibers of the products produced by the process of the present invention have a unique combination of properties: a molecular weight of about 100,000 to about 500,000, a modulus of at least about 200 f/denier, and a modulus of at least about 9 g/denier. It is a novel article in that it is a fiber with a tinacity of .

When the fiber is characterized by differential scanning calorimetry at a heating rate of about 10° C./min, at least one peak exhibits single or multiple melting peaks equal to or greater than about 246° C. For this fiber, the molecular weight is preferably from about 200,000 to about 450,000, and more preferably from about 300,000 to about 450.
,000. The tinacity is preferably at least about 12 ii'/denier, more preferably at least about 14 v/denier, and most preferably at least about 187 v/denier.

The tensile modulus is preferably at least about 3007 il/denier, more preferably at least about 4001 il/denier, and most preferably at least about 55027 denier. For preferred fibers of the present invention, when characterized by differential scanning calorimetry at a heating rate of 10°C/min, the fibers exhibit a single or multiple melting point with at least one peak equal to or greater than about 247°C. and in particularly clever embodiments of the invention at least one of the bath melting peaks is at a temperature equal to or greater than about 248°C. Most preferred of these particularly preferred embodiments are those in which at least one of the bath melt peaks is equal to or greater than about 249°C.

DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 schematically illustrates a first embodiment of the present invention;
To illustrate, the drawing step F followed by drying T and FJ is carried out on the xerogel fibers in two stages. In Figure 1,
The first mixing vessel 10 contains an ultra-high molecular weight polymer 11, for example, a weight average molecular weight of about 100,000 to about 500,000;
Preferably about 200,000 to 450,000 PV-
OH is provided and a relatively non-volatile m-th agent, for example glycerin, is also provided. The first mixing vessel 10 is equipped with a stirring device 13 . The residence time of the polymer and first bath agent in the first mixing vessel 10 is sufficient to form a slurry containing some dissolved polymer and some relatively finely divided polymer particles; through which it is delivered to the intensive mixing vessel 15. The powerful mixing vessel 15 is equipped with a spiral stirring blade 16. The residence time and agitation rate in the intensive mixing vessel 15 are such that they are sufficient to convert the slurry into a solution. Powerful mixing container] The temperature in 5 is externally heated, sura! J-1
The polymer is added to the bath agent at the desired concentration (
Generally, it will be found that 5-10% polymer (based on the weight of the solution) is high enough to completely dissolve the polymer. From the intensive mixing vessel 15 the solution is fed to the extrusion device 18 . The extrusion device]8 includes a barrel]9, and the extrusion device]8 includes a barrel]9;
/le] 9 contains a screw 2 operated by a motor 22.
The motor 24 drives the gear pump 23 and pumps the polymer solution at a fairly high pressure and at a controlled flow rate to the housing 23. The spinneret 25 has a plurality of holes for extrusion through a spinneret 25. The holes can be circular, X-shaped or oblong when it is desired to form fibers. be(·
When it is desired to form a single film, a relatively small long axis can be formed in the plane of the spinneret. The temperature of the solutions in the mixing vessel 15, in the extrusion device 18 and in the spinneret 25 are all below the gelling temperature (PV in glycerin).
-Q H is equal to the first temperature (e.g., 190°C) selected to be higher than about 25-100°C).
Or, it's higher.

This temperature may be changed from the mixing vessel 15 to the extrusion device 18 to the spinneret 251, for example, 190°C, 18°C.
0℃), or may be constant (for example, 1
90'C), but the polymer concentration in the solution must be substantially the same at one point. The number of holes, and therefore the number of fibers formed, is not a critical condition, but the usual number of holes is 1.
6.120 or 240.

The polymer solution coming out of the spinneret 25 passes through the air gap 27
pass through. The air gap 27 can be enclosed as desired;
It may be filled with an inert gas such as nitrogen, or optionally with a gas stream passed therethrough to aid in cooling.
・But it's okay. Multiple gel fibers 28 containing the first bath agent
passes through an air gap 27 and enters a quench bath 30 containing any of a variety of liquids. Thus, both the air gap 27 and the quench bath 300 allow the fibers to reach a second temperature 1 at which the solubility of the polymer in the first bath agent is relatively low, so that the polymer/bath agent system coagulates to form a gel. It is cooled down. Preferably, the quenching liquid in quench bath 30 is a hydrocarbon, such as paraffin oil. Although some stretching in the air gap 27 is acceptable, it is preferably less than about 10=1.

Rollers 31 and 32 in quench bath 30 operate to feed the fibers through the quench bath, and preferably with little or no stretching.

If some stretching occurs across rollers 31 and 32, some of the first solvent will leach out of the fiber. This solvent can be collected as an upper layer in the quench bath 30.

The cold first gel fibers 33 discharged from the quenching bath 30 hours advance to a bath agent extraction device 37. The extractor 37 is supplied with a relatively low boiling second bath agent, for example methanol, through a line 38. The solvent effluent in line 4o contains substantially all of the second bath agent and the first bath agent provided by the cold gel fibers 33.

The first bath agent is dissolved or dispersed in the second solvent. Thus, the fibrous structure 41 that is led out of the bath agent extractor 37 contains substantially only the second bath agent, and Containing a relatively small amount of the first bath agent, the fiber structure 41 will be slightly shrunk compared to the first gel fibers 33.

In drying device 45 , the second solvent is evaporated from fiber structure 41 to form essentially undrawn xerogel fibers 47 that are wound onto spool 52 .

If it is desired to operate the draw line from the spool 52, or from a plurality of such spools, at a slower feed rate than the take-off of the spool 52 will allow, the fibers are drawn around the driven feed roll 54 and the idler roll 55. The first heating tube 56 can be rectangular, cylindrical or any other convenient shape.
Add enough heat to bring it to ℃. Some of the fibers are drawn fibers 5
A relatively high draw ratio (e.g., 5:1) to form an 8
Stretched. The partially drawn fibers 58 are taken up by a drive roll and an idler roll 62.

The fibers from the rolls 61 and 62 are passed through a second heating tube 63 heated to a slightly higher temperature than the preceding fibers, for example 170 to 275°C, and then taken off by a drive take-off roll 65 and an idler roll 66. Rolls 65 and 66 are operated at a speed sufficient to provide the desired draw ratio in heating tube 63, for example a draw ratio of 1.8+1. The twice-drawn fiber 68 produced in this first embodiment is taken off by a take-off spool 72.

Referring to the six steps of the method of the present invention, it can be seen that the solution forming step A is performed in mixers 10 and 15. Extrusion step B is carried out by means of devices 18 and 23 and in particular via spinneret 25. Cooling process C is air gap 27
This is done by placing it in a rapid cooling bath for 30 minutes. The extraction step takes place in the bath agent extraction device 37. The drying step E takes place in the drying device 45. The stretching step F takes place in the elements 52 to 72, in particular the heating tubes 56 and 63. However, it will be appreciated that some stretching may take place even at temperatures substantially lower than the temperatures of heating tubes 56 and 63 and in various other parts of the system. Thus, e.g. , quenching bath 30
Within the bath agent extractor 37, within the dryer 45, or between the solvent extractor 37 and the dryer 45, some stretching
For example, 2:1) could occur.

A second embodiment of the present invention will be illustrated and explained as a schematic diagram in FIG. 2. Solution forming step A and extrusion step B of this second embodiment are substantially the same as the steps of the first embodiment illustrated in FIG. Thus, the polymer and the first solvent are mixed in the first mixing vessel]0, and the polymer is heated in the first bath agent f? J
The slurry is passed through line 14 to an intensive mixer 15 which is operated to form W'. Extrusion device 1
8 forces the polymer solution under pressure through a gear pump/housing 23 and then through a plurality of holes in a spinneret 27. Hot first gel fibers 28 pass through air gap 27 and quench bath 30, thus forming cold first gel fibers 33.

The cold first gel fibers 33 pass around a drive roll 54 and an idler roll 55, and then pass through a heating tube 57.

Heating tube 57 is generally the first heating tube 56 illustrated in FIG.
The longer (.0) fibers 33 are drawn through the heating tube 57 by a drive take-off roll 59 and an idler roll 60 to obtain a relatively high drawing ratio (for example, 1o:■). Fibers 35 enter extraction device 37 .

The extraction device 37 extracts the first bath agent &'! , the obtained second bath agent-containing fiber structure 42 is extracted from the gel fiber with the second bath agent.
is advanced to the drying device 45. The second solvent is then evaporated from the fibrous structure, and the xerogel fibers 48 are spooled onto a spool 52.

The fibers on spool 52 are then taken up by driven feed rolls 61 and idler rolls 62 and passed through heating tubes 63. The heating tube 63 is operated at a relatively high temperature of 1700 to 270°C. The fibers are passed through the heating tube 63 by a take-off roll 65 and an idler roll 6 operating at a speed sufficient to provide the desired draw, for example a draw of 18:1.
It is taken over at 6. The twice drawn fiber 69 produced in this second embodiment is wound onto a spool 72.

By comparing the aspect of FIG. 2 with the aspect of FIG.
The drawing process F is divided into two parts, the first part being carried out on the first gel fibers 33 in the heating tube 57 prior to extraction, and the second part being carried out after the drying CB). It will be seen that this is done on the xerogel fibers in the heating tube 63.

A third embodiment of the present invention will be illustrated and explained with reference to FIG. In this embodiment, the solution forming step A, the extrusion step B, and the cooling step C are substantially the same as the first embodiment of FIG. 1 and the second embodiment of FIG. Upon sniffing, the polymer and first solvent are mixed in a first mixing vessel 10 and the mixture is passed as a slurry through line 14 to an intensive mixing device 15. Here, the elastic mixing device 15 is operated to form a hot solution of the polymer in the first bath. Extrusion device 18 extrudes the polymer solution under pressure through gear pump/housing 23 and then through a plurality of holes in spinneret 25 . The heated first gel fibers 28 pass through an air gap 27 and a quenching bath 30;
The first gel fibers 33 are formed.

The cold first gel fibers 33 are advanced around a drive roll 54 and an idler roll 55 and through a heating tube 57. Heating tube 57 is generally longer than first heating tube 56 illustrated in FIG. In this third embodiment of FIG. 3, the speed of the fibers 33 is high compared to the speed of the xerogel fibers 47 between the tension spool 52 and the heating tube 56 in the first embodiment of FIG. The length of 57 is generally made so long to compensate for the fiber speed. The first gel fiber 33 is thus stretched to a desired draw ratio in heating tube 57, e.g. 5; It is taken up by a drive roll 61 and an idler roll 62 that can be operated as follows.

The first gel fiber 35 that has been stretched once is rolled on rolls 61 and 62.
The film is advanced into a heating tube 64 (modified from the original) and stretched by a drive take-off roll 65 and an idler roll 66. Drive roll 65 is operated fast enough to draw the fibers in heated tube 64 to the desired draw ratio, for example 18:1. The linear velocity in the heating tube 64 is relatively high because it is necessary to roughly match the velocity of the once-stretched gel fibers 35 coming out of the rolls 61 and 62, and therefore the heating tube 64 of the third embodiment shown in FIG. The second embodiment shown in FIG. 2 is longer than the heating tube 63 of the first embodiment shown in FIG.
Although it may leach from the fibers during drawing in tubes 7 and 64 (and be collected at the exit of each tube), the first bath agent is sufficiently non-volatile that the The twice drawn first gel fiber 36 is then passed through a bath extractor 37 where the second volatile solvent superimposes the first solvent. The fiber structure 43 containing substantially only the second bath agent is then dried in a drying device 45;
The twice drawn fiber 70 is then wound onto a spool 72.

As can be seen by comparing the third embodiment shown in FIG. 3 with the two embodiments shown in FIGS. is the cooling process C
It is carried out subsequent to (and before the solvent extraction step).

The method of the invention is further illustrated by the following examples.

Examples 1 to 14 Poly(vinylated I-Jikusanjino Katato-1-舊-, Die #E
Examples 1-14 below describe the processing and properties of fibers made from polyvinyl alcohol (PV-OH) polymers A, B', C% D and E. The intrinsic viscosity of these polymers was measured by the following method.

b) Measured directly in dimethyl sulfoxide (DMSO) at 35°C; and b) After reacetylation of polyvinyl alcohol (PV-OH) to PVAc, in tetrahydrofuran (THF) at 25°C. Measured in.

For polymers B, C, D, and E, the weight average molecular weight Mw was also measured by the direct light scattering method and the indirect light scattering method.The bath melting temperature of the polymer was measured at a heating rate of 10°C/min. A single melting endotherm was observed in each case.The results of these studies are shown in Table 14 and Table 1B below.

Table IA 4.62 -
234B 3.30 460,
000 232C2,76300,000232 D 2.39 250. QOo
226E 1.82 22
0.000 229F 3.42
' 500.000 231 No. IB Table A 2.41 811,000 88QOOO45
0,000B172s3cooo 58QOO029
'7,000C1,2435QOOO390,0002
00,000D --- E O,97257,000300,000153
,000p 1.73 5250'00 7oo,
ooo 358,000 yen Corresponding PV-OH In each example, a spinning solution of PV-OH in glycerol was prepared by Atlantic Research.
esearch Corporation) double spiral Miki Bodhisattva with oil jacket - [heli...■ (H
=li·', , @):). The vessel was sealed under nitrogen pressure and heated with stirring to 195°C for 2 hours to form a PV-OH solution.

The bottom outlet of the spiral mixer is equipped with a metering pump and a diameter 002
A 5 inch 1 hole capillary die was attached. The temperature of the spinning die was maintained at 185° C. as the solution was extruded from the die by a metering pump at a predetermined volumetric flow rate. The extruded solution filaments were quenched in a paraffin oil bath maintained at 10 DEG C., located at a distance of ~1 inch from the spinning die. The quenched gel filament was taken off at a first speed and then stretched at a given draw ratio at room temperature ().

The once drawn gel fibers were extracted in methanol to remove glycerol and then dried to remove methanol. The dried xerogel fibers were subjected to 1st step 2 as shown in Table 2.
Hot drawing was carried out in a nitrogen atmosphere in stages or three stages.

IA 13 195 1.84 5.7
3.52 A I3 195 1.8
4- 5.7 3.53 A 13 1
95 1. ．． 84. 5.7 3.54 A
13 195 1.84 5.7 3.
55 A I3 18.8 1,74 5
．． 5 3.56 A I3 188 1
．． 74 5.5. 3.57 B 13
200 1.40 4.5 5.58 C
I3 198 1.58 5.0 5.59
CI3 198 1.58 5.0 5.5
10 D 16 200 1.71 5.
4. 5.311 DI6 200 1
．． 71 5.4 5.312 B 20
．． 4 200 1.99 4.7 6.013
F 12 180 1.26 2.7
6.514 F 12 180 1.26
6.0 6.0 Chapter ■ Table (continued) 1 3 ・ --・ 2, 3 − , . 1.3-3. 3.
j , -m- 43,5-1,45- 53,0-,1,,,3- 6,,3,O,-1,31,2 71,8,,1,4- 81,85- 1,3=9 1.85 - 1.3 1.2. ,
.

10 1.75 1,40 1.2 , -1
1 1.75 1,40 1.3 -12
．． 2.25 1,25 1.50
.

13.2.0 1.5-- 14. 2.0. 1.2. 1.1 Examples 1-1
The tensile properties of the fibers of No. 4 were determined using standard methods. The results are shown in Table ■ below.

*, m-i ・15.0'-5983,929 3509,7' 261 4.7-204
34 14.4 613 3.
7 265 42. 13.5' 5
15 4.4 '276 33 lQ4
1 ”5'96 :3.'7 257 3
0 14.4 520 40 268
25 12.6 540 3.8 '2
39 29 13.3 55'5 3.6
``Se410 40 '12.4 468 4'
6 ′ Scarcity 611 39 12.6
523 4.6 2512 3j
13.4 598 3.6 24'
13 29 17.2 '585 3.7 3
014 '16 '18.2'''718 3
．． 8'32 Comparative Study of Physical Properties A number of experiments were conducted to illustrate the differences in properties between fibers produced according to the present invention and conventional fibers of the same or lower molecular weight. These experiments are carried out in the following
This is shown in paragraph 6.

(iiL scan power 01 J metry research example 2.4.
6.9 and 12 fibers with differential scanning power)! J-(D
SC). Samples weighing approximately 3 mg were run on a KinElmer DSC-■ apparatus at a heating rate of 10 DEG C./min. A plurality of melting peaks were observed as shown in Section (2) below.

In Table 1, the main melting peak (deepest endotherm) is underlined. The melting point of the fibers is 10-15°C higher than the polymer from which the fibers were made, and each fiber is at least 24 It has at least one melting peak at a temperature of °C.

The melting peak above 246°C is not previously seen in conventional fibers of the same or lower molecular weight.

Table ■ Example 2' 244.5, 248.1.251.2
58244.3.249.8.259 Example 4 244.8,253 Example 6 247.2,253.9 247.5,254.8 Example 9 248.2 Example 12 245.9 Example 2 The degree of crystal orientation of the fibers was measured by wide-angle X-ray diffraction. The degree of crystal orientation was 0998.

This is higher than previously found for conventional fibers of the same or lower molecular weight.

(3) Research on Water Resistance Several experiments were conducted to compare the water resistance of the fibers of the present invention shown in Examples 4 and 9 with the water resistance of conventional fibers of the same molecular weight or lower molecular weight. Ta.

The conventional fibers used in this study, designated as ``City PVA Fibers'', are commercially available products labeled by their manufacturers as ``High Modulus, High Tinacity, and Low Elongation''.

The results of this study are shown in Table V below.

Example 4 14.4 12.8
11 Example 9 13.3 1.1.4
14 Example 12 13.4
12.5 7 Commercially available pvH1 fiber 10.0
9.1 The results shown in Table 17 are:
The inventive fibers not only have greater original strength than commercially available PVA fibers, but also show higher retention of original strength after being immersed in water for 10 days at room temperature.

(4) Dimensional Stability Studies A series of experiments C45) were conducted to demonstrate the improved dimensional stability of the fibers of the present invention in comparison to the dimensional stability of conventional fibers. The fiber of the present invention selected for evaluation was Example 4.
9 and 12, while the conventional fiber is the commercially available PVA fiber of paragraph 3 above. In this test, standard shrinkage measurement methods were used to measure the shrinkage of the fibers from room temperature to 200°C and from room temperature to 240°C. The results are summarized in the following table. show.

Example 4 3.0 9.4 Example 9 2.2 6.7 Example 1
2 2.6 9.5 Commercially available PVA fibers 4.4 ' 10.7 As shown in Table ■, the fibers of the present invention are more dimensionally stable than "high modulus, high tinacity, low elongation" commercially available PVA fibers. It was found that the material has high elasticity, that is, less shrinkage.

(5) Study on creep property The fibers of the present invention are considered to exhibit lower creep properties under load and at elevated temperature at 160°C kneading than conventional fibers having the same or lower molecular weight.

[Brief explanation of drawings]

FIG. 1, FIG. 2, and FIG. 3 are diagrams schematically explaining the respective steps of three embodiments of producing polyvinyl alcohol fibers of the present invention. A...Spinning solution formation process B...Extrusion process C...
Cooling process D... Extraction process E... Drying process F...
Stretching step 10...First mixing container 11...Polymer 12.
...Non-volatile bath additives 15...Powerful mixing container 18...
Extrusion device 25... Spinneret 27... Air gap 28... Heat gel fiber 30... Quenching bath 3
5.58... Single drawn fiber 36.68.69.70.
・Twice drawn fiber 37...Extraction device 38...
Extraction bath agent line 41.43.43...Fiber structure 45...Drying device 47.48...Xerogel fiber 56.57...First heating tube 63.64...Second heating tube

Claims (10)

[Claims] (1) having a weight average molecular weight of about 100,000 to about 500,000, a tenacity of at least 9 g/denier and a tensile modulus of at least about 200 g/denier, and at a heating rate of about 10° C./min by differential scanning calorimetry; A polyvinyl alcohol fiber characterized in that it exhibits a single or multiple endotherms, at least one of which, when measured, is at a temperature equal to or greater than about 246°C. (2) The polyvinyl alcohol fiber of claim 1, wherein at least one endotherm is at a temperature equal to or greater than about 247°C. (3) The polyvinyl alcohol fiber of claim 2, wherein the at least one endotherm is at a temperature equal to or greater than about 248°C. (4) The polyvinyl alcohol fiber of claim 3, wherein at least one endotherm is at a temperature equal to or greater than about 249°C. (5) The weight average molecular weight of polyvinyl alcohol is approximately 30
The polyvinyl alcohol fiber of claim 1 having a molecular weight of 0,000 to about 450,000. (6) The polyvinyl alcohol fiber according to claim 1, having a tenacity of at least about 14 y/denier. (7) The polyvinyl alcohol fiber according to claim 6, having a tenacity of at least about 18 y/denier. (8) The polyvinyl alcohol fiber of claim 1 having a tensile modulus of at least about 500 g/denier. (9) The polyvinyl alcohol fiber of claim 8 having a tensile modulus of at least about 600 g/denier. (10) (a) Prepare a solution of legged polyvinyl alcohol having a weight average molecular weight of about 100,000 to about 500,000 in a first solvent having a first polyvinyl alcohol concentration of about 5% to about 35% by weight. (b) extruding the solution, which is substantially at the first concentration upstream and downstream of the extrusion hole and at a temperature equal to or higher than the first temperature upstream of the extrusion hole, from the extrusion hole; cooling the solution adjacent and downstream of the extrusion hole to a second temperature below the temperature at which a rubbery gel is formed to form a first bath agent-containing gel of substantially infinite length; (d ) the first solvent-containing gel with a second volatile solvent;
extracting for a contact time sufficient to form a second solvent-containing fibrous structure, the gel being of substantially unlimited length substantially free of the first solvent; (e) drying the second bath agent-containing fibrous structure to form a substantially infinite length xerogel free of first and second solvents; gel, (ii) the second solvent-containing fibrous structure, and (iii) the xerogel at a total draw rate sufficient to achieve a tenacity of at least about 9 g/denier and a modulus of at least about 200 g/denier. 10 by differential scanning calorimetry.
Polyvinyl alcohol fibers characterized in that they exhibit single or multiple endotherms, at least one of which is at a temperature equal to or greater than about 246°C when measured at a heating rate of 0°C/min.