JPH11107046A - Polyvinyl alcohol-based flame-retardant yarn and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject inexpensive flame-retardant yarn having low toxicity of combustion gas, excellent strength, excellent durability of washing resistance and handle, useful as protection clothing, etc., an industrial material, etc., comprising a vinyl alcohol-based polymer, a halogen-containing polymer and specific fine particles in a prescribed ratio. SOLUTION: This yarn is a sea-island yarn comprising a vinyl alcohol-based polymer 1 and a halogen-containing vinyl polymer 2 such as a vinyl chloride- based polymer, etc. The component 1 is a sea component, the component 2 is an island component and the blending ratio of the component 1/the component 2 is 95/5 to 55/45 by weight. Preferably the yarn contains 0.1-10 wt.% based on the total weight of the polymers of fine particles 3 having 0.8-4.6 m<2> surface area based on 1 g of one or more compounds selected from the group consisting of a tin compound such as tin oxide and an antimony compound such as antimony pentoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl alcohol (hereinafter abbreviated as PVA) flame retardant fiber having excellent flame retardancy and a method for stably producing the same.

[0002]

2. Description of the Related Art Conventionally, flame-retardant fibers include acrylic and polyester fibers copolymerized with a flame-retardant comonomer, regenerated cellulose fibers into which a flame-retardant agent has been kneaded or reacted, and the polymer itself having a flame-retardant property. Thermoset fibers, aramid fibers, cotton and wool post-processed with flame retardant agents are on the market. Acrylic fiber generates cyan gas when burning,
Polyester fiber has melt drip, thermosetting fiber has low fiber strength, aramid fiber is extremely expensive, cotton and wool have problems such as texture hardening due to post processing and poor washing durability, and improvements are being studied respectively. .

[0003] On the other hand, PVA-based flame-retardant fibers are also disclosed in
No. 12920, JP-B-49-10823, JP-B-51-19494 and the like. PVA-based flame-retardant fiber emits a small amount of gas by pyrolysis, but does not have a melt drip.It is suitable for clothing such as protective clothing, living materials such as curtains and carpets, and industrial materials such as car seats and vehicle spring receiving materials. It is suitably used for various purposes.

[0004] The PVA-based flame-retardant fiber contains polyvinyl chloride (hereinafter abbreviated as PVC) and a flame-retardant aid such as metastannic acid, tin oxide and antimony oxide having a particle diameter of 1 to 3 µm. Further improvement is required in terms of balance between flame retardancy and cost.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide both excellent flame retardancy and cost performance.
To provide a PVA-based flame-retardant fiber and its industrially stable production method,
An object of the present invention is to provide a VA-based flame retardant fiber.

[Means for Solving the Problems]

That is, the present invention comprises a PVA-based polymer (1) and a halogen-containing vinyl polymer (2), wherein (1) is a sea-island fiber having a sea component and (2) is a sea-island fiber having an island component. )
Is 95: 5 to 55:45, and the surface area per 1 g of at least one compound selected from the group consisting of tin compounds and antimony compounds is 0.8 g.
The PVA-based flame-retardant fiber is characterized in that fine particles (3) having a particle size of about 4.6 m ² are contained in an amount of 0.1 to 10% by weight based on the total weight of the polymer. Furthermore, the present invention provides a spinning dope containing a PVA-based polymer (1), a halogen-containing vinyl polymer (2), and at least one compound (3) selected from the group consisting of tin compounds and antimony compounds in a coagulation bath. In producing a PVA-based flame-retardant fiber by wet or dry-wet spinning, drying, drawing and, if necessary, heat-treating, as a supply method of (3), (3) is added to a stock solution solvent in an amount of 1%.
~ 30% by weight, Mohs hardness 8 or more, diameter 0.1
A method for producing a PVA-based flame-retardant fiber, comprising using beads having a diameter of about 5 mm and wet-pulverizing and dispersing the compound until the surface area per 1 g of the compound becomes 0.8 to 4.6 m ^2. Is the way.

Hereinafter, the present invention will be described in detail. First, the sea component, that is, the matrix component of the fiber of the present invention must be PVA. PVA is the only polymer capable of forming a strong intermolecular hydrogen bond due to a hydroxyl group that enables a strong sea-island fiber with a halogen-containing vinyl polymer (hereinafter abbreviated as PVX) that imparts flame retardancy. PVA as used in the present invention means a polymer having a vinyl alcohol unit of 70 mol% or more of all the constituent units, and therefore, ethylene, vinyl acetate, itaconic acid, vinylamine, acrylamide, vinyl pivalate, maleic anhydride, sulfone A monomer such as an acid-containing vinyl compound may be copolymerized at a ratio of less than 30 mol%. The degree of saponification is preferably 80 mol% or more, and for orientation crystallization, 95 mol% of all the constituent units.
PVA is more preferably a vinyl alcohol unit, more preferably 98 mol% or more, more preferably 9 mol% or more.
It is at least 9 mol%, most preferably at least 99.8 mol%. However, when the solidification bath contains an alkaline substance such as caustic soda, an aqueous solution of PVA having a degree of saponification of more than 99 mol% has poor mechanical stability and is alkali-saponified when passing through the solidification bath. The degree of saponification of PVA used as a raw material is preferably 95 to 99 mol%. The degree of polymerization of PVA is not particularly limited, but is preferably 500 or more, more preferably 1500 or more in order to obtain high-strength fibers. Further, in order to improve the hot water resistance, a post-reaction such as intramolecular and / or intermolecular acetalization of PVA may be performed after fibrillation with an aldehyde compound represented by formaldehyde.

Further, the island component of the fiber of the present invention must be PVX (halogen-containing vinyl polymer). PVX for island ingredients
The fiber of the present invention can be used as a flame-retardant fiber for the first time. PVX in the present invention is a halogen element,
That is, it is a vinyl polymer having 50% or more of units containing fluorine, chlorine, bromine and iodine. For example, vinyl chloride polymer (PVC), vinylidene chloride polymer, vinyl bromide polymer, vinylidene bromide polymer, chlorinated polyolefin, brominated polyolefin and the like are included. Among them, PVC is preferred in terms of flame retardancy, heat decomposition resistance, and cost. PVX has a low degree of crystallinity, lacks fiber-forming ability, or has low strength even if it is formed into fibers.In particular, PVX fibers are manufactured by the wet spinning method, which is a cost-effective method for producing staple fibers. Not. Therefore, PVX is an island component in the fiber of the present invention,
Used as a functional polymer for imparting flame retardancy.

To make PVA a sea component and PVX an island component, PV
A is preferably 55% by weight or more and PVX is 45% by weight or less. PVA
If the content is less than 55% by weight, PVX may partially become a sea component, which is not preferable in terms of performance. In addition, PVA exceeds 95% by weight and P
When VX is less than 5% by weight, the amount of halogen in the fiber is small and the flame retardancy becomes insufficient, which is not preferable. Flame retardance,
Depending on the balance of strength, etc., the mixing ratio of PVA / PVX is 90/10 ~
The ratio is preferably 55/45, more preferably 80/20 to 60/40. In the present invention, a polymer other than PVA and PVX may be added as long as the object of the present invention is not impaired.

Further, the fiber of the present invention comprises at least one compound selected from the group consisting of a tin compound and an antimony compound, and has a surface area of 0.8 to 1 g.
The fine particles of 4.6 m ² are 0.1% based on the total weight of the polymer.
1010% by weight must be contained. The surface area of the tin compound or antimony compound referred to in the present invention is defined as the formalization treatment of a fiber sample in a fixed length state, insolubilization of PVA, embedding in an epoxy resin, creation of an ultrathin section (about 800 nm in thickness), RuO ₄ vapor Perform staining, observe the ultra-thin section of the resulting fiber cross section at a magnification of 20,000 with a transmission electron microscope,
It is calculated from the average diameter of at least 50 tin compound or antimony compound particles arbitrarily selected from the obtained electron micrographs, assuming a perfect sphere having the average diameter.

The tin compound referred to in the present invention is not particularly limited as long as it is a compound containing a tin element. However, in view of the effect of enhancing flame retardancy as a flame retardant aid and cost performance, inorganic compounds such as tin oxide and metastannic acid are used. Oxides are preferred. The antimony compound referred to in the present invention is not particularly limited as long as it is a compound containing an antimony element. However, inorganic oxides such as antimony pentoxide and antimony trioxide in terms of flame retardant enhancing effect as a flame retardant aid and cost performance. Are preferred. Tin compounds and
If the content of the antimony compound is less than 0.1% based on the total weight of the polymer, the flame retardancy is insufficient. Ten%
However, even if it is contained in an amount exceeding the above range, the flame retarding effect reaches a plateau, which is disadvantageous in terms of cost performance. The content of the tin compound and / or the antimony compound is preferably from 0.5 to 8% by weight, more preferably from 1 to 6% by weight.

In the fiber of the present invention, the surface area per 1 g of the tin compound and the antimony compound as the flame retardant aid is 0.1 g.
It is characterized by using fine particles of 8 to 4.6 m ² ,
1 compared to those used for conventional PVA-based flame retardant fibers
One of the most important points of the present invention is to use a material having a large surface area per g, that is, a material having a small particle size, and to find that the flame retardancy is greatly improved. It is not clear why the flame retardancy is improved by using a flame retardant auxiliary having a large surface area, but it is roughly estimated as follows. That is, when PVX is exposed to a high temperature and decomposed by combustion, hydrogen halide gas is generated, and this gas reacts with these flame-retardant assistants in a solid state to generate tin halide and antimony halide. The tin halide and antimony halide suppress the combustion by capturing the radicals generated during the combustion of the fiber and promote the carbonization of PVA, and the flame retardant effect is exhibited. It is presumed that the key point is that gaseous hydrogen halide and solid-phase tin or antimony react efficiently and generate more tin halide or antimony halide effective for suppressing combustion. Therefore, if the same weight is used, it is presumed that increasing the surface area of the solid, that is, tin or antimony has a large flame-retardant effect. As described above, the solid phase reaction between a hydrogen halide and a tin compound or an antimony compound is extremely important in terms of the flame retardant mechanism. Here, even when most of the surface area of the tin compound and / or the antimony compound is less than 0.8 m ² per gram,
Although a certain degree of flame retardancy is obtained, the reactivity between the hydrogen halide and the tin compound and / or the antimony compound is low due to the small reaction surface area, and the flame retardancy index (LOI) is low. On the other hand, setting the surface area per gram to a value exceeding 4.6 m ² is effective for flame retardancy, but technically difficult. Preferably one of a tin compound or an antimony compound
This is the case where the surface area per g is 3.0 to 4.6 m ² .

Next, a method for producing the fiber of the present invention will be described. First, the spinning dope must be formed from PVA and PVX, and at least one compound selected from the group consisting of tin compounds and antimony compounds. Examples of the solvent for the spinning dope include polar organic solvents such as dimethylsulfoxide (hereinafter abbreviated as DMSO), dimethylacetamide, dimethylformamide, and water. In the case of a polar organic solvent, a common solvent for PVA and PVX is used. On the other hand, in the case of water, PVA dissolves, but PVX does not dissolve in water. Therefore, an aqueous emulsion of PVX having an emulsion particle size of 0.01 to 0.08 μm and an aqueous PVA solution are mixed. Further, in order to obtain a high-strength fiber, boric acid may be added to a mixed aqueous solution of PVA and PVX emulsion. A single or mixture of a tin compound or an antimony compound is added thereto to obtain a spinning dope. The concentration of the polymer in the stock solution is preferably in the range of 10 to 30% by weight.

The method of dissolving the polymer is not particularly limited, and two types of polymers may be dissolved individually in an undiluted solvent and mixed at an appropriate ratio. The method of adding and dissolving a polymer or the method of dissolving two kinds of polymers at the same time can be adopted, and the spinning dope contains acids and antioxidants as stabilizers for the polymers, as well as colorants and other additives. Can be used without any problem.

The spinning dope thus obtained is wet-spun or dry-wet spinning through a spinning nozzle into a solidification bath. The wet spinning method, in which the solidification bath is brought into direct contact with the spinning nozzle, is suitable for spinning using a multi-hole nozzle because the fibers can be spun without causing the fibers to stick together even if the nozzle hole pitch is narrowed. Dry-wet spinning with an air gap between them is suitable for high-speed spinning because the elongation at the air gap is large. In the present invention, the wet or dry-wet method can be appropriately selected depending on the purpose and application.

The solidification bath used in the present invention differs depending on whether the stock solution is an organic solvent or an aqueous solution. In the case of a stock solution using an organic solvent, a mixed solution consisting of a solidified solvent and a stock solution solvent is preferable from the viewpoint of the obtained fiber strength and the like, and as the solidified solvent in that case, alcohols such as methanol and ethanol, acetone, methyl ethyl ketone and the like are used. An organic solvent having a solidifying ability for PVA such as ketones is preferable, and the composition ratio of the solidifying solvent / stock solution in the solidifying bath is 2%.
5/75 to 85/15. The solidification bath is preferably set to a low temperature of -5 to 20C from the viewpoint of uniform solidification. On the other hand, in the case of an aqueous solution, a solidification bath composed of an aqueous solution of sodium sulfate is used. As the stock solution to which boric acid is added, a mixed aqueous solution of caustic soda and sodium sulfate is used. It is preferable to use a low-temperature organic solvent-based solidification bath in terms of uniform solidification, strength, and dry / wet dimensional stability, as compared with the case of using an aqueous solidification bath.

The yarn formed in the solidification bath is sent to a dry heat drawing step after wet drawing, extraction of a stock solution solvent, and drying. In the method of the present invention, it is necessary to perform dry heat stretching so that the total stretching ratio becomes 6 times or more. The total draw ratio in the present invention is a ratio represented by a product of a wet draw ratio and a dry heat draw ratio.
Fibers with excellent Young's modulus cannot be obtained.

The pulverization and dispersion method of a tin compound or an antimony compound as a flame retardant aid is a point of the fiber production method of the present invention. That is, in the fiber production method of the present invention, the flame retardant auxiliary is dispersed in the same solvent as the stock solution solvent by 1 to 30% by weight,
Mohs hardness of 8 or more and diameter of 0.1 to 5 as crushed beads
Using a bead of mm, the flame-retardant auxiliary is wet-pulverized until the surface area per gram becomes 0.8 to 4.6 m ² . When the dispersion concentration is lower than 1% by weight, it is necessary to lengthen the pulverization dispersion time. When the dispersion concentration exceeds 30% by weight, the pulverization and dispersion time is short, but the obtained flame-retardant auxiliary is liable to re-agglomerate, the viscosity of the dispersion is increased, and the handleability is poor. The dispersion concentration of the flame retardant aid is preferably from 4 to 25% by weight, more preferably from 8 to 20% by weight, from the viewpoints of the pulverization dispersion time, the anti-agglomeration property, and the handleability of the dispersion. In addition, reaggregation can be prevented by using an undiluted solvent as a medium for pulverization.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The strength and elongation in the examples are measured in accordance with JIS L-1013. The flame retardancy index (LOI) is JIS K
Measured according to 7201.

Example 1 PVA having a degree of polymerization of 1750 and a degree of saponification of 99.8 mol% was
PVC with 10 mol% of vinyl acetate, D with metastannic acid
Introduced to MSO. Metastannic acid is 0.65 mm diameter Zr beads (Mohs hardness 9 to 10) as a 15% DMSO solution.
Was charged into a Dynomill pulverizer (KDL-PILOTA type manufactured by Shinmaru Enterprises) which had been charged in advance, and pulverized at 3350 rpm for 8 minutes. This at 80 ° C for 1
Stir and dissolve at 150 rpm in a nitrogen stream for 0 hour to obtain a mixed spinning dope containing a weight ratio of PVA / PVC of 65/35, a polymer concentration of (PVA + PVC) of 18% by weight, and metastannic acid of 5% by weight / polymer. Was. This 80
The spinning stock solution at a temperature of 1000 ° C. was prepared with 1,000 holes and a hole diameter of 0.08 m.
Then, the mixture was wet-spun through a spinneret having a weight ratio of DMSO / methanol of 30/70 and a temperature of 5 ° C. in a solidifying bath.
Subsequently, the film was wet-stretched 3.5 times while extracting DMSO with methanol, dried with hot air at 100 ° C., and stretched 4-fold at 228 ° C. The obtained fiber has a thickness of 1.8 denier, and the cross-sectional TEM photograph of the cross section magnified 20,000 times with a transmission electron microscope (TEM) shows that the PVA has the sea and the PVC has the island-in-sea structure. The diameter was 0.7 μm. Also from the same photo,
The average surface area of metastannic acid in the fibers was found to be 1.8 m ² / g. The strength of this fiber is 8.6g / d, LOI value is 42
And high strength, high flame retardant fiber.

Comparative Example 1 Metastannic acid obtained in Example 1 was added by pulverizing with a vibration mill using alumina balls having a diameter of 15 mm (Mohs hardness of 9 to 10) for 22 hours. Although the strength of the obtained fiber was 8.5 g / d, which was an excellent physical property, the average surface area of metastannic acid in the fiber obtained from the TEM cross-sectional photograph was as small as 0.5 m ² / g,
The LOI value was 39, which was lower than that of Example 1.

Example 2 PVC emulsion having a particle size of 0.06 μm, having a degree of polymerization of 1750 and a degree of saponification
98.5 mol% of PVA, metastannic acid, boric acid and metastannic acid were added to water. Metastannic acid was introduced as a 15% aqueous solution into a Dynomill pulverizer in which 1 mm diameter Zr beads (Mohs hardness 9 to 10) had been put in advance, and 5% at 3350 rpm.
Milled for minutes. Stir and dissolve this at 90 ° C for 5 hours, and use PVA / PVC
= 65/35, a stock solution of (PVA + PVC) having a polymer concentration of 20%, a composition of metastannic acid 5% / polymer, and boric acid 2.5% / PVA was obtained.
The resulting spinning stock solution was wet-spun through a spinneret having 1,000 holes and a hole diameter of 0.08 mm into a solidification bath consisting of an aqueous solution of 45 ° C. containing 20 g / l of caustic soda and 350 g / l of sodium sulfate. Roller stretching by 1.5 times, neutralization in a neutralization bath from an aqueous solution of sulfuric acid and sodium sulfate, and in a saturated aqueous sodium sulfate solution at 95 ° C for 2.
3 times wet stretching, washing with boric acid in a 30 ° C water washing bath, replacement with sodium hydroxide with 300g / l aqueous solution of sodium hydroxide, drying at 100 ° C, stretching 4.0 times dry heat at 228 ° C, 5% dry heat at 230 ° C After shrinking, a PVA-based flame-retardant fiber was obtained by a water-based spinning method. The obtained fiber has a thickness of 2 denier and a cross-sectional TEM whose cross section is enlarged by 20000 times by TEM.
According to the photograph, the PVA has the sea-island structure and the PVC has the island-island structure, and the island diameter of the PVC is 0.05 μm. From the same photograph, it was found that the average surface area of metastannic acid in the fiber was 1.3 m ² / g. The fiber had a strength of 6.2 g / d and an LOI of 41.

Comparative Example 2 In Example 2, meta-stannic acid pulverized by a vibration mill using alumina balls having a diameter of 15 mm (Mohs hardness of 9 to 10) was added. Although the strength of the obtained fiber was 6.1 g / d, which was an excellent physical property, the average surface area of metastannic acid in the fiber obtained from the TEM cross-sectional photograph was as small as 0.6 m ² / g, and the LOI value was also low. 38
And lower than Example 2.

[0024]

According to the present invention, flame-retardant acrylic fiber, flame-retardant polyester fiber, thermosetting fiber, aramid fiber, flame-retardant cotton, flame-retardant wool, and other non-PVA flame-retardant fiber materials are used. , Combustion gas toxicity, melt drip properties, strength, cost,
Aims to improve PVA-based flame-retardant fiber, which is excellent in terms of washing resistance and texture, and uses PVA, a general-purpose polymer as the main polymer, blends PVX, a flame-retardant polymer, and further promotes flame retardancy. In a fiber in which a tin or antimony compound as a mixing agent is mixed, the surface area of the flame-retardant aid is increased, and the flame-retardant performance is greatly improved even with the same composition. The fiber of the present invention is used in the field of protective clothing such as combat uniforms and firefighting suits, the field of industrial materials such as car seats and vehicle spring receiving materials and air filters, curtains, carpets, blankets, blankets, sheets covers, and cotton fillings. It can be used effectively in the field of living materials.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akio Omori 1621 Sazu, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (3)

[Claims] 1. A composition comprising a vinyl alcohol polymer (1) and a halogen-containing vinyl polymer (2), wherein (1) is a sea component,
(2) is a sea-island fiber of an island component, wherein a mixed weight ratio of (1) and (2) is 95: 5 to 55:45, and at least one kind selected from the group consisting of a tin compound and an antimony compound; The surface area per 1 g of the compound is 0.8 to
A polyvinyl alcohol-based flame-retardant fiber, characterized in that fine particles (3) of 4.6 m ² are contained in an amount of 0.1 to 10% by weight based on the total weight of the polymer. 2. The fiber according to claim 1, wherein (2) is a vinyl chloride polymer. 3. A spinning dope containing a vinyl alcohol polymer (1), a halogen-containing vinyl polymer (2), and at least one compound (3) selected from the group consisting of tin compounds and antimony compounds. In producing a polyvinyl alcohol-based flame-retardant fiber by performing wet or dry-wet spinning in a bath, drying, drawing, and further heat-treating as necessary,
As a supply method of (3), (3) is added to the undiluted solvent in 1 to 30 times.
% By weight, Mohs hardness of 8 or more, diameter of 0.1 to 5
The production of a polyvinyl alcohol-based flame-retardant fiber, characterized in that a dispersion of the compound is wet-milled and dispersed until the surface area per 1 g of the compound is 0.8 to 4.6 m ² using beads having a diameter of 1 mm. Method.