JPH03193914A - Conjugate polyvinyl alcohol monofilament and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject filament having high knot strength and useful as a fishing-net, rope, etc., by using a PVA polymer having high polymerization degree as the component A and a PVA polymer having lower polymerization degree as the component B, dissolving both components in a solvent, subjecting the obtained spinning dope to dry or wet spinning and drawing the obtained filament. CONSTITUTION:(A) A PVA polymer having a viscosity-average polymerization degree of 1,500-7,000 and (B) a PVA polymer having a viscosity-average molecular weight of >=1,500 and smaller than that of the component A are dissolved in a solvent and the obtained spinning dope is subjected to dry or wet spinning from a conjugate spinneret in such a manner as to form the core layer with the component A and the sheath layer with the component B and to get a cross-sectional area ratio of the core layer to the sheath layer of 10/90 to 70/30 (preferably 15/85 to 65/35). The obtained undrawn filament is drawn to a fineness of >=100 denier to obtain the objective monofilament.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composite polyvinyl alcohol (hereinafter abbreviated as PVA) monofilament having excellent knot strength and a method for producing the same.

(Prior art) PVA fiber has the highest strength and highest initial elastic modulus among general-purpose fibers, and is used as sewing thread for rubber reinforcement materials, plastic reinforcement materials, cement reinforcement, fibers, and materials.

It is used as a fiber for industrial materials such as single-ply fishing nets and robes.

However, PVA fibers are inferior in knot strength, fatigue resistance, and hot water resistance compared to polyamide and polyester fibers, which prevents their application to applications that particularly require these physical properties. For this reason, many proposals have been made regarding methods for improving the above-mentioned physical properties of PVA fibers. For example, Japanese Patent Publication No. 47-8186 discloses that the strength and fatigue resistance of PVA fibers are improved by wet spinning a spinning stock solution containing oxalic acid.

Methods have been proposed to improve hot water resistance. However, the physical properties of the fibers obtained with this method are

It was not comparable to polyamide or polyester fibers, and was particularly inferior in knot strength.

Recently, Japanese Patent Application Laid-Open No. 61-252313 discloses that the knot strength is improved by spinning a PVA solution with a degree of polymerization of 1500 or higher, removing the solvent, stretching, and then hot stretching in a heating tube set at 220°C or higher. A method for producing superior PVA-based fibers is disclosed. However, with this method, only fibers with a single filament fineness of 5 deniers or less, high knot strength, and...

It was not possible to obtain a monofilament with a large fineness.

In addition, in Japanese Patent Application No. 1-130799, the present inventors reported that the tensile strength was 10 g/d or more and the initial elastic modulus was 200 g.
We proposed a method for producing PVA monofilament yarn with a fineness of 100 deniers or more and a fineness of 100 deniers or more. However, although this method achieved improvement in tensile strength and initial elastic modulus, it was not possible to improve knot strength.

(Problems to be Solved by the Invention) As mentioned above, various methods for manufacturing PVA fibers having high knot strength and methods for manufacturing PVA monofilaments having high strength and high initial elastic modulus have been proposed. However, no PVA monofilament with high knot strength was obtained.

Therefore, the first object of the present invention is to provide a PVA monofilament having high knot strength comparable to polyamide or polyester fibers, and the second object of the present invention is to provide a PVA monofilament having high knot strength comparable to polyamide or polyester fibers. The goal is to provide a method for manufacturing with high productivity.

(Means for Solving the Problems) The present inventors have made extensive studies to solve the above problems, and have found that in order to improve the nodule strength.

The cross section of the monofilament is made of PV with different viscosity average degree of polymerization.
The present invention was achieved by discovering that it is important to have a core-sheath structure made of A-based polymer.

That is, the gist of the present invention is a first-order configuration.

(1) A monofilament with a core-sheath structure in which two types of polyvinyl alcohol polymers with different viscosity average degrees of polymerization are joined, in which the polyvinyl alcohol polymer (A) with a high viscosity average degree of polymerization is used as the core layer and the viscosity average The polyvinyl alcohol polymer (B) with a low degree of polymerization is used as the sheath layer, the ratio of the cross-sectional area of the core layer and the sheath layer is 10/90 to 70/30, and the fineness is 100 denier or more. Characteristic composite polyvinyl alcohol monofilament.

(2) A polyvinyl alcohol polymer (A) with a viscosity average degree of polymerization of more than 1,500 and 7,000 or less, and a polyvinyl alcohol polymer (A) with a viscosity average degree of polymerization of 1,500 or more and smaller than the polyvinyl alcohol polymer (A). The spinning dope prepared by dissolving the coalescence (B) in a solvent is prepared such that the A component becomes the core layer, the B component becomes the sheath layer, and the ratio of the cross-sectional area of the core layer and the sheath layer is 10/90 to 70. A method for producing a composite polyvinyl alcohol monofilament, which comprises dry/wet spinning from a composite spinneret to form an undrawn yarn such that the yarn has a fineness of 100 denier or more.

Hereinafter, nine aspects of the present invention will be described in detail.

The PVA-based polymers (hereinafter abbreviated as polymers) A and B used in the present invention have a saponification degree of 99 mol%.
Examples of the above include linear PVA with a low degree of branching, and those in which a small amount of olefin monomer is copolymerized as a copolymerization component.

It is preferable that the viscosity average degree of polymerization (hereinafter abbreviated as 9 degree of polymerization) (OFA) of Polymer A is more than 1500 and not more than 7000, and the degree of polymerization (OP,) of Polymer B is 1500 or more and smaller than DPA. .

In the present invention, the difference in the degree of polymerization between polymers A and B (DPA
DPB) is not particularly limited, but is preferably 300 or more, more preferably 1000 or more, still more preferably 1500 or more. As mentioned above.

The degree of polymerization of Polymer A is 7000 or less from the viewpoint of cost, and the lower limit of the degree of polymerization of Polymer B is preferably 1500 or more in view of the physical properties of the obtained monofilament. is less than 5500.

The degree of polymerization as used in the present invention refers to the apparent viscosity average degree of polymerization calculated from the following empirical formula.

[η] =5.08xlO−'xDP0·'7115 where [η] (cH!/g) is the intrinsic viscosity measured at 20°C using dimethyl sulfoxide as a solvent.

A spinning stock solution is prepared by dissolving these two types of polymers with different degrees of polymerization in a solvent. The solvent may be a saturated aliphatic polyhydric alcohol such as glycerin, ethylene glycol, or propylene glycol, or dimethyl sulfoxide (hereinafter referred to as , DMSO), 1,3-dimethyl-2-imidazolidinone, water, etc., and mixtures thereof, among which DMSO, water,
Or a mixture thereof is preferably used. Although the solvents for polymers A and B do not necessarily need to be the same, in order to further improve the physical properties of the obtained monofilament, it is preferable to use the same solvent to improve mutual adhesion. In the present invention, a polymer heat-resistant agent, a pigment, a crosslinking agent, etc. may be appropriately mixed into the above-mentioned solvent.

The concentration of the polymer in the spinning stock solution is preferably adjusted to a range of 2 to 35% by weight. If the polymer concentration is less than 2% by weight, the spinnability is too low and spinning becomes difficult, and if it is more than 35% by weight, the drawability of the resulting undrawn yarn is reduced and the strength is difficult to improve.

Furthermore, polymer A solution and polymer B at spinning temperature
Preferably, the concentrations of both polymers are adjusted so that the viscosities of the solutions are substantially equal. For example, when polymers with a degree of polymerization of 5,000 and 3,300 are used as polymers A and B, respectively, the concentration of the polymer A solution is adjusted to about 12% by weight, and the concentration of the polymer B solution is adjusted to about 16% by weight.

In the present invention, the two types of spinning dope prepared as described above are dry-spun and wet-spun to form an undrawn yarn. It is extremely important to spin the fibers so that the polymer A solution with a high degree of polymerization (component A) forms the core layer and the polymer B solution with a low degree of polymerization (component B) forms the sheath layer.

The above-mentioned monofilament with a core-sheath structure is manufactured by using two gear pumps to produce the monofilament inside a composite spinneret as shown in Fig. It is possible to obtain the polymer A solution through the hole 1 and the polymer B solution through the outer discharge hole 2 into an inert atmosphere layer such as air.

In the present invention, the area occupied by polymer A (component A), which is the core layer, in the cross section of the monofilament.

The area ratio (composite ratio: A/B) occupied by the polymer B (component B), which is the sheath layer, is 10/90 to 70/30. It is preferable to adjust the discharge amount of each gear pump so that it is preferably in the range of 15/85 to 65/35. If the area ratio is outside this range, the composite effect will be small and it will be difficult to obtain the desired high nodule strength.

Note that the cross-sectional shape of the monofilament does not necessarily have to be circular, but even if a spinneret with an irregular cross-section is used, it may be difficult to obtain the expected irregular shape due to the fluidity of the spinning dope, and the ease of manufacturing the spinneret may be considered. Therefore, there is no need to intentionally create an irregular cross section.

It is industrially advantageous to have a circular cross section.

In addition, the desired high knot strength can be easily obtained by creating a concentric double core-sheath structure without eccentricity of the centers of the core layer and sheath layer.

The filament extruded from the spinneret as described above is
The yarn is introduced into a coagulation bath or a cooling bath through an inert atmosphere layer to become a solidified yarn, and then an undrawn yarn is formed through an extraction step with an extraction liquid.

As the coagulation bath and extraction liquid, alcohols such as methanol and ethanol, and ketones such as acetone can be used, and methanol is particularly preferably used.

In addition, PVA, such as decalin or paraffin oil, does not have coagulating power and is introduced into a cooling bath made of a solvent that is incompatible with the PVA solvent, solidified into threads, and then subjected to the extraction process using the extract liquid described above. You can guide me.

In the present invention, the undrawn yarn obtained above is wound up once or continuously supplied to a drawing process and drawn to a fineness of 1.
Monofilament of 00 denier or more.

In addition, in the present invention, other processes such as drying, oil treatment, etc. may be appropriately introduced between the dry/wet spinning process and the stretching process, if necessary.

Various methods can be applied as the stretching method.9 For example, a method in which the undrawn yarn is stretched while being in contact with a heating body such as a heat plate, a method in which the yarn is stretched in a heating medium, and a method in which the yarn is stretched by a dielectric heating method. can be mentioned. In these methods, stretching can be performed in one stage or in multiple stages of two or more stages, but
It is preferable to stretch in multiple stages of two or more stages. Further, in the case of multi-stage stretching, moisture application, lubricant application, etc. may be performed between the m-th stage stretching and the (m+1>th stage stretching (m is an integer of 1 or more)).

In order to obtain a composite PVA monofilament having high knot strength, which is the object of the present invention, the total stretching ratio is preferably 10 times or more, more preferably 15 times or more.

According to the present invention, the commercially available degree of polymerization is 1500.
As described above, it is possible to manufacture a composite PVA-based monofilament of 100 denier or more with excellent knot strength with good productivity by using two types of PVA of 7000 or less.

Furthermore, the composite PVA monofilament of the present invention thus obtained has an excellent knot strength of 4.5 g/d or more, and a tensile strength of 8 g/d or more.
Because it has excellent physical properties with an initial elastic modulus of 120 g/d or more, it can not only be used for fishing nets and robes, which are typical uses of PVA fiber, but also for cement,
It can also be used as a reinforcing material for plastics and as an asbestos substitute.

It is a fiber suitable for various industrial material applications.

(Function) The reason why the composite PVA monofilament of the present invention has high knot strength is not clear, but it is thought to be as follows.

In other words, although no theoretical explanation has yet been found regarding the expression of knot strength in monofilaments, conventionally,
It has been empirically known that in order to obtain monofilaments with high knot strength from melt-spun polymers, it is effective to use a polymer with low flexibility as a sheath component.

In the PVA-based composite monofilament of the present invention, a polymer with a high degree of 9-polymerization (that is, the degree of crystallinity tends to increase when stretched and has low flexibility) forms the core layer, and the polymer has a low degree of 9-polymerization (that is, even when stretched, it does not crystallize). This is because the sheath layer is made of PVA-based polymer (which does not have a very high degree of oxidation and is highly flexible).

It is thought that the strain inside the yarn that occurs when the monofilament is knotted is alleviated by the deformation of the low polymerization degree polymer, and the damage to the high polymerization degree polymer is reduced, and therefore high knot strength is developed.

In addition, in the manufacturing method of the present invention, if PVA-based polymers that differ only in degree of polymerization are used for the core layer and sheath layer, and the same solvent is used as the solvent for both polymers, the adhesion between the core layer and the sheath layer is good. Therefore, the knot strength of the PVA-based composite monofilament can be further improved.

(Example) Next, the present invention will be specifically explained using examples.

In addition, the tensile strength, initial elastic modulus, and knot strength are as per JIS-
Measurements were made in accordance with L-1013 at a gripping interval of 25 cm and a pulling speed of 30 cm/coin.

Example 1. Comparative Examples 1 and 2 Polymerization degree 5000 (saponification degree 9) manufactured by Unitika Chemical Co., Ltd.
9.8 mol%) and 3300 (degree of saponification 99.5 mol%) PVA polymers with concentrations of 12% by weight and 1%, respectively.
A spinning stock solution prepared by dissolving in DMSO to give a concentration of 6% by weight was prepared using a composite spinning method using 1 PVA polymer solution (A) with a polymerization degree of 5000 as a core layer, 9 PVA polymer solution (B) with a polymerization degree of 3300 as a sheath layer. A composite monofilament with a core-sheath structure was manufactured.

That is, two types of spinning stock solutions are extruded from a composite spinneret,
After dry and wet spinning in methanol bath.

DMSO was extracted with methanol and dried to obtain an undrawn yarn. At this time, the discharge amounts of polymer solutions A and B were set so that the composite ratio was 25/75.

Next, the obtained undrawn yarn was heated to an inlet temperature of 180°C.

Stretched in a hot air heating furnace set at an exit temperature of 250°C,
A monofilament was obtained.

In addition, as Comparative Examples 1 and 2, 1 degree of polymerization was 5000 and 33.
Monofilaments each consisting of a single component were spun from a PVA polymer solution of 0.00 under the same conditions as in Example 1.

Table 1 shows the physical properties of each monofilament obtained.

As is clear from Table 1, the monofilament of Example 1 had a high knot strength of 5.1 g/d;
The monofilaments of Comparative Example 1.2 each weighed 3.1 g/
d, was only 3.4 g/d.

Example 2. Comparative Example 3 Polymerization degree 5000 (saponification degree 99.8 mol%) and 17
A spinning stock solution prepared by dissolving PVA polymer of 0.00 (degree of saponification 99.5 mol%) in DMSO to a concentration of 12% by weight and 24% by weight, respectively, was subjected to composite spinning and stretching in the same manner as in Example 1. A monofilament was obtained.

For comparison, PVA polymers with polymerization degrees of 5,000 and 1,300 were prepared in the same manner from spinning stock solutions prepared at concentrations of 12% by weight and 29% by weight, respectively. Table 1 shows the physical properties of the obtained monofilament.

Comparative Example 4 A monofilament was obtained by spinning yarn under the same conditions as in Example 1 except that the composite ratio was changed to 5795.

As shown in Table 1, a monofilament with high knot strength could not be obtained with the above composite ratio.

Comparative Example 5 A polymer solution with a polymerization degree of 5000 was added to the sheath layer 1 with a polymerization degree of 3300.
A monofilament was produced in the same manner as in Example 1, except that the polymer solution was used as the core layer.

Although the obtained monofilament had the highest tensile strength among all the examples, the knot strength was the lowest.

(Effects of the Invention) The composite PVA monofilament of the present invention has high knot strength comparable to polyamide or polyester fibers. This is an unprecedented monofilament for PVA fibers, and as a result, it can not only be used for fishing nets and robes, which are the typical uses of PVA fibers, but also used as reinforcing materials for cement, plastics, etc., and as an asbestos substitute. This fiber is suitable for various industrial material applications.

Further, according to the method for producing a composite PVA monofilament of the present invention, it is possible to produce a PVA monofilament having the above-mentioned advantages with high productivity and at low cost.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an embodiment of a core-sheath type composite spinneret used in the present invention.

Claims (2)

[Claims] (1) A monofilament with a core-sheath structure in which two types of polyvinyl alcohol polymers with different viscosity average degrees of polymerization are joined, in which the polyvinyl alcohol polymer (A) with a high viscosity average degree of polymerization is used as the core layer and the viscosity average The sheath layer is a polyvinyl alcohol polymer (B) with a low degree of polymerization, the ratio of the cross-sectional area of the core layer to the sheath layer is 10/90 to 70/30, and the fineness is 100 denier or more. Characteristic composite polyvinyl alcohol monofilament. (2) A polyvinyl alcohol polymer (A) with a viscosity average degree of polymerization of more than 1,500 and less than 7,000, and a polyvinyl alcohol polymer (A) with a viscosity average degree of polymerization of 1,500 or more and smaller than the polyvinyl alcohol polymer (A). The spinning dope prepared by dissolving the coalescence (B) in a solvent is prepared such that the A component becomes the core layer, the B component becomes the sheath layer, and the ratio of the cross-sectional area of the core layer and the sheath layer is 10/90 to 70. A method for producing a composite polyvinyl alcohol monofilament, which comprises forming an undrawn yarn by dry/wet spinning from a composite spinneret so that the yarn has a fineness of 100 deniers or more.