JPS639041B2 - - Google Patents

Description

Detailed Description of the Invention The present invention relates to the production of saponified ethylene-vinyl acetate copolymer fibers by melt-spinning a saponified ethylene-vinyl acetate copolymer having a specific composition and melt properties under specific conditions. It is about the method.

In general, saponified ethylene-vinyl acetate copolymers have higher melting point, hardness, tensile strength, bending strength, bending rigidity, etc., as well as solvent resistance and Excellent abrasion resistance. Furthermore, since it has excellent adhesion to various polymeric materials as well as organic and inorganic base materials, it is widely used as a coating agent, binder, or lamination adhesive for these various base materials.

For example, Japanese Patent Publication No. 49-36078 discloses the use of a saponified ethylene-vinyl acetate copolymer in the form of powder, thread, or fiber having a specific composition as a heat-sealing adhesive for textiles. .

The present inventors found that a fibrous saponified ethylene-vinyl acetate copolymer is particularly excellent as an adhesive for such fibers and textiles, and conducted intensive studies on its fiberization. However, spinnability varies greatly depending on the composition and melt properties of the saponified material used, as well as the spinning conditions. It has been found that it is necessary to limit the composition and melt properties of the saponified material and the spinning conditions to specific ranges. That is, as a result of detailed study, the present inventors found that ethylene-
By melt-spinning saponified vinyl acetate copolymer under specific conditions, fibers with excellent stability and uniformity can be obtained without causing problems such as yarn breakage even during continuous spinning for long periods of time. discovered a spinning method,
The present invention has now been completed.

That is, the present invention provides a saponification rate of 90% or more obtained by saponifying an ethylene-vinyl acetate copolymer having a vinyl acetate content of 41 to 55% by weight in the presence of an alkali metal hydroxide and/or alkoxide. A saponified ethylene-vinyl acetate copolymer with a residual alkali metal content of 0.2% by weight or less and a melt index of 5 to 100 is melt-spun at a spinning temperature of 150 to 210°C and a winding speed of 100 to 1000 m/min. The present invention provides a method for producing saponified ethylene-vinyl acetate copolymer fibers, which comprises spinning and, if necessary, stretching.

Ethylene, which is the raw material resin for the saponified ethylene-vinyl acetate copolymer used in the present invention.
Vinyl acetate copolymer has a vinyl acetate content of 41~
It is limited to 55% by weight, preferably in the range of 41-50% by weight. Here, if the vinyl acetate content of the raw material copolymer is higher than 55% by weight, not only the melt viscosity of the saponified copolymer will increase significantly, but also the thermal stability will deteriorate. It is unsuitable because it causes gelation, making melt spinning difficult. On the other hand, if a vinyl acetate content lower than 41% is used, the crystallinity of the saponified product will be low and the melt viscosity will be too low, resulting in poor spinnability and uneven fineness during spinning. It has a tendency to break easily. Moreover, it is unsuitable because the thread winding workability becomes poor.

The above-mentioned ethylene-vinyl acetate copolymer may be produced by a known method such as a high-pressure polymerization method, a solution polymerization method, an emulsion polymerization method, or the like. Also,
This raw material copolymer may optionally be a third comonomer copolymerizable with ethylene and vinyl acetate, such as unsaturated hydrocarbons such as propylene, butene-1, styrene, or (meth)acrylic acid and its ester. Copolymerization of about 10% by weight or less of various derivatives such as maleic acid and its anhydrides, unsaturated carboxylic acids such as esters, and derivatives thereof can be used.

The saponified ethylene-vinyl acetate copolymer used in the present invention can be produced by a known method using the above-mentioned ethylene-vinyl acetate copolymer as a raw material. For example, homogeneous solution reaction in a good hydrocarbon solvent such as toluene or xylene or a mixed solvent containing methanol or ethanol, or a powder or pellet-like reaction in a non-solvent using an alcohol such as methanol or ethanol. The polymer can be prepared by a heterogeneous reaction in which the polymer is saponified while maintaining its original shape. The saponification reaction is conveniently carried out in the presence of an alkali metal hydroxide and/or methoxide, such as sodium or potassium.

The saponified product produced in this way has a saponification degree of
90% or more, alkali metal residual amount 0.2% by weight or less,
Limited to those with a melt index of 5 to 100.
If the saponification rate is lower than 90%, the stringiness tends to gradually deteriorate and is therefore unsuitable. In addition, the melt index is 5 from the relationship between melt viscosity and stringiness.
A range of 100 to 100, preferably 10 to 80 is suitable.
In addition, the saponified product produced by the saponification reaction contains the alkali used and acetate by-produced by the reaction. If the content of these alkali metals exceeds 0.2% by weight, the thermal stability and weather resistance of the saponified product will deteriorate significantly, so neutralization treatment with organic or inorganic acids such as acetic acid or phosphoric acid or solvent cleaning is required after the saponification reaction. However, it is necessary to remove the alkali metal remaining in the saponified product until the amount is 0.2% by weight or less, preferably 0.1% by weight or less.
In addition, during melt spinning, volatile contents such as water and solvent contained in the saponified material are reduced by 0.2% by weight.
It is desirable to dry it so that it is preferably 0.1% by weight or less. In addition, for the saponified product,
Antioxidants, light stabilizers, heat stabilizers, as necessary.
Various additives such as lubricants, antistatic agents, inorganic and organic colorants, etc. can also be added.

Melt spinning of the saponified ethylene-vinyl acetate copolymer is generally carried out using an extruder. There are no particular restrictions on the structure of the extruder, and a screw extruder similar to that used for extrusion of thermoplastic resins or fiber processing can be used. Furthermore, in order to increase the accuracy of the amount of melt extruded and to increase the uniformity of the spun yarn, an extruder with a gear pump attached to the tip thereof is generally used. There are no particular limitations on the hole diameter, hole length, and number of holes in the spinneret. Further, the holes may have any shape, but those having a shape in which the cross section of the spun fibers is usually circular or triangular are used. The spinning temperature is limited to 150 to 210°C due to the relationship between the melt viscosity of the saponified resin and the spinnability, but especially 180°C.
A range of ~210°C is preferred. Note that a high temperature of 210° C. or higher is not preferable because the thermal stability of the saponified resin deteriorates. In general, the hydroxyl group content is high;
The lower the saponified material with a lower melt index is used, the higher the spinning temperature needs to be.

The thread extruded from the extruder nozzle has a winding speed of 100
It is wound up at a speed of ~1000m/min. As a result, a thread that is continuously stable and has good uniformity can be obtained. The fineness of the spun undrawn yarn is not particularly limited, but is usually preferably in the range of 5 to 200 deniers/strand.
The obtained undrawn yarn can be drawn as necessary. At that time, the stretching temperature is 10 to 80℃, preferably 30 to 60℃, and the stretching ratio is 2 to 6 times, and the stretching speed is
A range of 50 to 1000 m/min is suitable. In addition, there is no limit to the fineness of the drawn yarn, but it is usually 1 to 100.
A denier/strand is appropriate. As a result, a fiber having excellent fiber properties can be obtained.

The yarn produced in this way can also be made from cotton, nylon, polyester, polyacrylonitrile,
It can also be blended, twisted, and woven with natural or synthetic fibers such as polypropylene, vinylon, and acetate. The yarns and fiber products produced in accordance with the present invention are particularly useful as adhesives for the various natural or synthetic fibers described above. For example, it is suitably used as an adhesive for interlining of textiles. In addition, it can be used as an adhesive for various inorganic materials such as metals, glass, and ceramics, and organic materials such as paper, wood, and synthetic resins. Furthermore, it can be widely used as various textile products.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

In addition, each measurement value shown in this invention was measured by the following method.

(1) Vinyl acetate content of ethylene-vinyl acetate copolymer and its saponification rate It was determined by the neutralization titration method in accordance with JIS-K-6730-1977.

(2) Melt index Measured at 190°C under a load of 2.16 kg in accordance with JIS-K-6730-1977. The unit of measurement value is g/
It is 10min.

(3) Residual amount of alkali metal in saponified material Measured by flame photometry in accordance with JIS-K-0102-1974.

Example 1 Ethylene-vinyl acetate copolymer pellets with a vinyl acetate content of 43% by weight and a melt index of 60 were dissolved in methanol in the presence of sodium hydroxide from 70% to 70% by weight.
Saponified pellets obtained by saponification at 80°C with a saponification rate of 99%, a residual amount of sodium of 0.078% by weight, and a melt index of 24 were heated in a nitrogen atmosphere using a 25 mmφ single screw extruder (screw length/diameter = 15).
Extrusion was carried out at a resin temperature of 210°C. After sending this molten liquid into a gear pump, a sand filter with 7 to 20 meshes and a mouthpiece with a built-in 60 mesh stainless steel (hole diameter 0.8mmφ, number of holes 12, hole shape,
It was extruded from a circular cylinder at a rate of 1 kg/hour. This was continuously wound onto a bobbin at a winding speed of 280 m/min.
During spinning, there were no problems such as yarn breakage, and stable spinning was possible. The resulting yarn had good uniformity and a fineness of 45 denier/strand. This yarn was further passed through a drawing machine at a temperature of 50°C and a drawing speed of 120°C.
The yarn was drawn at a rate of m/min to obtain a yarn (15 denier/strand) with a draw ratio of 3 times.

Example 2 The method of Example 1 was repeated except that the yarn winding speed was 700 m/min. As a result, it was possible to continuously produce yarn with a fineness of 18 denier/strand with good uniformity.

Example 3 Saponification rate of 95% obtained by alkali saponification of an ethylene-vinyl acetate copolymer with a vinyl acetate content of 41% by weight and a melt index of 31, residual amount of sodium
The procedure of Example 1 was repeated except that 0.005% by weight saponified pellets with a melt index of 15 were used. As a result, it was possible to continuously produce yarn with a fineness of 46 denier/strand with good uniformity.

Comparative Example 1 Saponified pellets with a saponification rate of 99%, a residual sodium content of 0.072% by weight, and a melt index of 29 obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 21% by weight and a melt index of 32 were Using the extruder used in Example 1, the spinning temperature was 150
The yarn was spun at 190° C., but spinnability was poor at both temperatures and continuous spinning was not possible.

Comparative Example 2 A saponified powder with a saponification rate of 98%, a residual sodium content of 0.054% by weight, and a melt index of 26 was obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 65% by weight and a melt index of 87. Although extrusion was carried out using the extruder used in Example 1 under the same conditions as in Example 1, the melt gelatinized and spinning was impossible.

Comparative Example 3 In Example 1, the same saponified material as in Example 1 was used, except that a saponified material with a residual amount of sodium in the saponified material of 0.74% by weight was used, and extrusion was carried out under the same conditions as in Example 1. Due to the poor thermal stability of the melt, decomposition occurs, causing mucus to form around the mouthpiece.
In addition, thread breakage occurred frequently during spinning, making spinning impossible.

Comparative Example 4 In Example 1, the spinning temperature was 250°C and 120°C.
Extrusion was carried out under the same conditions as in Example 1 except that the temperature was changed to .degree. As a result, when the spinning temperature is 250℃, the viscosity of the melt becomes too low and the spinnability is poor due to thermal deterioration, and when the spinning temperature is 120℃, the melt viscosity increases significantly. In either case, satisfactory spinning could not be achieved.

Comparative Example 5 A saponification rate of 73% by weight obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 36% by weight and a melt index of 54, and a residual amount of sodium.
A saponified powder containing 0.025% by weight and a melt index of 37 was extruded and spun under the same conditions as in Example 1 at a resin temperature of 185°C. During spinning, thread breakage sometimes occurred, and the obtained thread was not uniform and had many irregularities.

Comparative Example 6 A saponified powder with a saponification rate of 99%, a residual sodium content of 0.027% by weight, and a melt index of 2 obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 30% by weight and a melt index of 5 was Although it was extruded under the same conditions as in Example 1, the stringiness was poor.
I could not spin the yarn satisfactorily. In addition, due to the high melt viscosity, the load on the gear pump became excessive and became unstable, resulting in a decrease in the accuracy of the extrusion amount.

Comparative Example 7 Saponification rate of 99% and residual amount of sodium 0.022 obtained by saponifying an ethylene-vinyl acetate copolymer with a vinyl acetate content of 37% by weight and a melt index of 300.
Extrusion was carried out under the same conditions as in Example 1 except that a saponified powder with a melt index of 170 and a spinning temperature of 130°C and 150°C was used, but the spinnability was poor due to the low melt viscosity, and the spinning I couldn't do it.

Claims (1)

[Claims] 1. In a method for producing saponified ethylene-vinyl acetate copolymer fiber, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 41 to 55% by weight is mixed with an alkali metal hydroxide and/or alkoxide. Ethylene, obtained by saponification in the presence of ethylene, has a saponification rate of 90% or more, a residual alkali metal content of 0.2% by weight or less, and a melt index of 5 to 100.
Spinning saponified vinyl acetate copolymer at a temperature of 150 to 210
A method for producing a saponified ethylene-vinyl acetate copolymer fiber, which comprises melt-spinning at 100° C. and a winding speed of 100 to 1000 m/min, and further stretching if necessary. 2. The method for producing saponified ethylene-vinyl acetate copolymer fibers according to claim 1, wherein the stretching temperature is 10 to 80°C and the stretching ratio is 2 to 6 times.