JPS5943112A - Manufacture of polyvinyl alcohol synthetic fiber - Google Patents

Abstract

PURPOSE:To prepare the titled synthetic fiber having excellent alkali resistance and adhesivity to cement, and suitable as a reinforcing material for cement, by extruding a polyvinyl alcohol spinning solution containing boric acid or a copper salt into a specific coagulation bath. CONSTITUTION:A polyvinyl alcohol spinning solution added with boric acid or a copper salt such as cupric sulfate, is extruded into a coagulation bath containing sodium hydroxide, sodium sulfate, etc. wherein the concentration of the caustic alkali (Xg/l) and that of the dehydrating salt (Yg/l) satisfy the conditions of formulas I , II and III at the same time. The spun fiber is subjected to the neutralization treatment and wet-heat treatment, washed with water, dried, drawn by hot drawing in hot air, and heat treated preferably at >=200 deg.C (especially 230-250 deg.C) to obtain the objective polyvinyl alcohol synthetic fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyvinyl alcohol (hereinafter abbreviated as PVA)-based synthetic fiber, and more specifically relates to a method for producing PVA-based synthetic fiber suitable as a reinforcing material for cement. It is something.

The first wet spinning method for PVA-based synthetic fibers is PVA
A method is known in which a system aqueous solution is spun into a coagulation bath of a saturated aqueous solution such as sodium sulfate (hereinafter abbreviated as sulfate). The fibers obtained by this method have a horseshoe-shaped cross section and a double structure. However, since the fiber strength and Young's modulus are not so high, it is not sufficiently effective as a reinforcing material for cement, etc. A second known method is to spin a PVA-based aqueous solution into a concentrated alkaline coagulation bath. Does the fiber obtained by this method have high strength and Young's modulus? However, the cross section of the fiber is circular. Thirdly, a method is known in which boric acid, copper salt, etc. that form chelate crosslinking are added to an aqueous PVA solution, and the resulting solution is spun into a coagulation bath of a small amount of caustic alkali and a saturated aqueous salt solution. The performance of the fiber obtained by this method is high strength and Young's modulus, but the cross section of fR wholesale I
It is a tsI circular shape.

On the other hand, material properties required for cement-based molded products and various structures include bending strength, impact strength, and cracking strength. Various reinforcing materials are used for this purpose. In other words, inorganic fibers and organic fibers are being dispersed into the cement matrix as reinforcing materials. A representative example of inorganic fibers is slate boards containing asbestos, and glass fiber-reinforced cement molded products containing alkali-resistant glass fibers. Or is it made of cement with reinforcing materials such as steel fibers? Shapes are also known. On the other hand, polyethylene is an organic fiber. Some synthetic fibers such as PVA or polypropylene are also used as reinforcing materials.

However, stone! VC''A is recognized as a gas-causing substance and poses a health hazard.Also, all supplies are dependent on imports, resulting in instability.Also, slate boards have low impact strength in terms of performance. ．There is a problem that the value is low.Also,
Resistance: Alkali glass fiber does not have perfect alkali resistance, and its bending strength decreases over time after cement formation, so its use is limited to non-structural materials, such as curtain walls and exterior wall panels. However, there is also the problem of workability in that skin disorders occur. On the other hand, regarding synthetic fibers, the PVA-based composites mentioned above. :Nari*'
As seen in M, the cross-sectional shape of the fiber is circular. ．． Ellipse 1
2. Because it is cedar or horseshoe-shaped, there is no contact with cement.
In contrast, as a PVA-based synthetic fiber with deformed fiber cross-section,
! I? Japanese Unexamined Patent Publication No. 56-140113 proposed a method of mixing calcium carbonate, etc., and Japanese Unexamined Patent Publication No. 56-154513 proposed a method of mixing and spinning with magnesium sulfate, etc. ``'4 ・Unstable spinning 1 ・Additionally, a mixture? There is a problem in that the management of the moist heat bath is complicated because a part of it is eluted into the bath.

Seven fibers. When reinforcing molded products etc. It is generally accepted that the higher the fiber strength and Young's modulus, the higher the bending strength of the molded product, and the higher the adhesive strength between the fiber and cement, the more sufficient the reinforcing effect will be. It is also generally accepted that

Therefore, the present inventors discovered that the alkali resistance is good. Our mission is to provide a method for easily manufacturing fibers with high strength and young modulus, good adhesion to cement, excellent reinforcing effect on cement, and no health or skin problems. and.・Results of intensive research. Contains boric acid or copper salts?
The P■/A-based spinning stock solution having the following properties is spun into a specific coagulation bath.
? Discovered the fact that the above aspirations can be achieved by manufacturing fibers. To the present invention. What we have reached...
It is.

That is, the present invention is based on PVA to which boric acid or copper salt has been added.
The concentration of alkali (XIl/t) and the concentration of dehydrating salt (Y11/t) of the spinning dope are as follows (a). (b)-(
c) It is spun into a coagulation bath that satisfies the conditions of formula at the same time, and then subjected to conventional neutralization and moist heat treatment, followed by washing with water and drying.
This is a method for producing PVA-based synthetic fibers, which is characterized by subjecting it to further K hot stretching.

Y≦415-1.68X (a) Y≧850-5X (b) Y≧185-0.58X (e) According to the present invention, the horseshoe-shaped, til! Is it circular? Fibers are obtained which have an angular cross section, which was not observed in the case of a circular cross section, and in some cases have protrusions of 1 to 3 μm.

In order to produce PVA-based synthetic fibers by the method of the present invention, it is necessary to use a PVA-based spinning dope to which boric acid or copper salt has been added.

Examples of copper salts used in the present invention include sulfuric acid-1?
Examples include water-soluble copper salts such as copper, cupric sulfate, and copper nitrate. Particularly preferred is cupric sulfate. The amount of boric acid or copper salt added is 0.3 to 4 parts by weight, preferably 0.6 to 2 parts by weight, based on PVA.

The preferred average degree of polymerization of PVA used in the present invention is 1000.
~2500, especially 1300-1800. PVAo
Although the degree of saponification is not particularly limited, it is preferably 99.5 to 98 mol. The concentration of PVA in the spinning stock solution is 10-2
5 weight chi. Particularly preferred is 14 to 20 weight. The PR of the spinning dope is preferably in the range of 4.0 to 548, since gelation occurs when the dope becomes alkaline, and on the other hand, if it becomes too low, problems of corrosion of equipment etc. occur.

In the present invention, such a spinning stock solution is used. The caustic alkali concentration (XI/t> and the degree of dehydrating salts #' degree (Y1/t) simultaneously satisfy the conditions of the above formulas (a)-'(b).(c).Spinning in a solid bath It is necessary to.

Figure 1 shows the coagulation bath properties of the present invention, but the vertical axis shows the concentration of 1. ), and the area surrounded by diagonal lines is the νf hard bath area of the present invention.

As a causative alkali v”. For example, caustic soda. Potassium is a good soil. The concentration of caustic alkali is 13
In the case of γ4 without 19/t. The resulting fiber. The cross section of {[ is 11'1 circular. On the other hand, the purchasing surface of "over 209 glt" is circular. Dehydrating salts and
Magnesium acid, sodium nitrate, etc. can be found in the river, but!
[This is C. Yobousou, who is very friendly with the male. If the concentration of dehydrating salts is 14% alkali or 130E/t, 2009/t
It reached almost saturation at [2. On the other hand, if it is less than 64 ji/L, the spinning quality is poor. (a.) 5 (.:U,!] High'6: λ degree caustic alkali or dehydration {'Lj
The solid bath is almost saturated with dehydrating salts.
1-2, and formula (b) and formula (e), the content of caustic alkali or dehydrating salts is low. The temperature of the coagulation bath is 35-55℃: 40-55℃.
℃ is preferable.

Wood invention V here. After leaving the coagulation bath, the yarn is neutralized using the conventional method 1 (after being subjected to moist heat treatment, washed with water, dried, and further heated to 4!
F: Stretch. Heat 1r'. Shin (followed by 20 old: 10,
If necessary, heat treat at 230 to 2.50C.

To the method of the invention. Shiri {! ! 'v: hru Pv 8 series synthetic combination shoulder? ). It is water-based and alkaline, so it is compatible with cement matrix. And it is not attacked even in cement matrix. It also has a high Young's modulus (7% Z). Juichi 9 this s: *. Not reinforced with px ip/r. Cement forming crystal (.li: box J7-/bending rjia degree and crack 11, +jh. strength 41' drying.

or. According to the method of the present invention, the horseshoe shape of the /ζ property N11 and the circular shape and the horizontal shape of the circular shape and &;
It has a deformed 11゛＾but4 called tlA. Juichi) Te. When mixed with cement, it exhibits an adhesive effect with cement due to its anchoring effect. Again, yes! !
Since the given consideration has an elongation of 114 degrees 17):'7t, it is also effective in improving the impact resistance.

Obtained by the method of the present invention 1f. f[{il.
J river L? 5i! When forming a cement laminate using the paper-making method, considering the fiber addition amount of 0, the dispersibility of the fibers in the cement matrix, the bending strength, and the impact strength, the 25M [Sadly, especially 0.5~2 double E
The λ coefficient is 1'.

Hereinafter, the present invention will be explained in more detail with reference to Example 1-1.

In addition, the preparation and performance measurement of fiber 1 reinforced cement board r:l:,
PVA-based synthetic glue λzIf (2 to 6 mml) was cut into 4 pieces!・I did it as follows.

(1) Bending strength: 1 x 4, impact strength: 22 parts, bulge: 3 parts. part, special clay 10 weight t part sharp; ljl Bonoretland cement 85
2. Mix the heavy M part. Wet papermaking method
The laminate was molded and then cured in humid air for 2811 hours to create a 1-7 cement board. The tit tip strength and Charpy impact strength of this slate board were measured. Toughness C ↓ Bending strength measurement chart 1 It is shown as an area ratio from a piece of paper.

(2) Crack strength i. :RAJk. Ordinary Boltland cement, silica sand No. 5, and water were mixed in a ratio of 0.003:1:2:0.5, and the resulting mortar was tested using the ring restraint test method (steel ring with an inner diameter of 83 m. mortar ring 20mm thick)
The number of days for cracks to occur was determined.

(3) Adhesiveness with fiber cement Add 0.2 weight of fiber to the cement, make the total ratio of water and cement 0.5, and use ordinary boltland cement as cement. iiqa;i was dispersed.

This material was cured for 411 days at 20℃ in a humid atmosphere.
A temporary template was obtained, and the obtained cement slab was fractured. The discharge length of the fibers at the fracture surface was measured. (The way of discharge is ℃σ is close to I'
1. is selfish. ) Example 1.2. Comparative Examples 1 to 3 Average polymerization 1131490 (7) PVA appetizer: 16% degree strength 1
6.2, fI], and added PVA to the bath solution, i. :Add 1 boric acid of triple stitch φ
Eyes. A spinning fabric was prepared by adjusting pu to 57. This spinning stock solution was mixed with sodium hydroxide (15 t) g/t and sulfate (1.601 g/t). Spinning 1-2 using a 50C alkaline bath as a coagulation bath at /l-, after stretching 418 IJl between the first and second rollers, acid containing gold 3001/t, sulfuric acid 2511/t Neutralized at 40℃ in a Shioto bath, followed by an acidic salt bath containing 3'609//, sulfuric acid and 20g/t of sulfuric acid. So after performing + moist heat treatment at 90? Use, wash, and even oil? agent treatment [,. 235℃ after drying
A PVA-based synthetic fiber was obtained by subjecting it to constant length heat treatment at 24° C. (Example 1).

It's a moat, change the hot stretching ratio from 4x to 3.5x? l) VA-based synthetic fiber was obtained under the same conditions as in Example 1. (Example 2). ? Table 1 shows the performance of the obtained fibers. The cross section of the fiber was as shown in FIG. 2 (Example 1) and FIG. 3 (Example 2). Also, the performance Q of cement board made using ζ fibers. It was as shown in Table-1.

For comparison, the coagulation bath was changed as shown below. is Example 1
The fibers were produced under the same conditions. Below, as in Example 1, what are the properties of fiber and cement board? Measuring ability.

The results were as shown in Table-1. Anti-fiber Comparative Example 1; AsOg/t, sodium hydroxide 15117
'l-'mgll1.50C. (Figure 4) Comparison Example 2: Sodium hydroxide 'U't 3'50g/t. Temperature 2o?
one? d (koji 51 tuna)? :゛ru m4u? 3': Bowsalt 42bI/t. Temperature 40℃
(FIG. 6) However, in Comparative Example 3, it was not possible to collect sample i at 4'' hot stretching, so a fiber was produced at 248 times hot stretching.

Comparative example 2' Asbestos reinforcement (slate board) PVA-based synthetic fiber additive-free? The cement laminate 1 is
? Risota: Iru? The fibers obtained in Example 1 were slightly higher than the fibers in Comparative Example 1.2. Young's modulus is shown.Furthermore, the fiber cross section is deformed.★The '+a' fiber obtained in Example 2 has a lower Young's modulus and strength than the fibers of Comparative Examples 1 and 2. In addition, the cross-sectional surface of the fibers is irregularly shaped.Cement using this fiber as a reinforcing material: The performance of the board with the fiber-reinforced cement of the example is better than that of the comparison and control examples. Ta.

: Example 2 strength. Although fibers with a slightly lower Young's modulus are used, the cross section is irregularly shaped and becomes IA', so it is presumed that this is due to the excellent reinforcement effect.

Project? Example 3, Comparative Example 4.5 PVA with an average degree of polymerization of 1300 was used at a concentration of 18:((', J
P' in the resulting rδ liquid.
Add 1.3 weight of boric acid to iV・A' and
was adjusted to i5.7 and spun at i5.7 to create a stock solution. Is this spinning stock solution sodium hydroxide? lium zoae7t, bow salt g'
o. /L 50C alkaline? Salts? The bath was spun as a coagulating bath, and the following was carried out in the same manner as in Example 11.
f:' Manufactured 3, the performance of the obtained fibers is shown in Table-・2・
To? show. In addition, the 4/7 tl game of the weft was as shown in Figure 7.・Also, this fJv! The performance of the cement board created using ifft is shown in Table 2.・For comparison, one sample was prepared with the coagulation bath changed as follows.
Fibers were produced using the same strips as 21J2, and the performance of the 4-mounted K4LIi support cement board was measured in the same manner as in Example 2.

The cross section G dimension of the fiber was as shown in Figure 8.9.

Comparative example 4: 350 &/L of sulfur salt, 1 liter of prium hydroxide
5y7t, temperature 50°C (Fig. 8) Lt Comparative Example 5: Water FA f}') Um3Ei01/L. (
Fa [7η was reduced in Example 3 at 20°C! :')! 14f:
Compared to the fiber K of Comparative Example 4.5, the performance ('.1 is almost unchanged, but the cross section is irregularly shaped -C).Perhaps for this reason, the performance of the cement board of Example 3 was superior f1.

Example 4. Comparative Examples 6 to 9 I) VA with a molecular polymerization degree of 1680 was used at a concentration of 16.2'ii
'j. - P is dissolved in water so that it becomes a
A κJi yarn stock solution was prepared by adding 1.3 wt.
A salt bath of alkaline IHL at 50°C was spun at I/T as a pseudo-solid bath. Fiber production was carried out in the following manner (I'lJ1 and J).The performance of the obtained fiber K' is shown in Table 3.
Shown below. Further, the cross section of the fiber was as shown in FIG. Furthermore, the performance of the cement board made using this fiber was as shown in Table 3.

For comparison, Comparative Examples 6 and 7 were made under the same conditions as Example 4 except that the coagulation bath was changed as follows.
91C-), no boric acid was added to the spinning dope. Fibers were produced under the same conditions as in Example 4, except that the coagulation bath and hot drawing ratio were changed as follows.
Measuring the performance of Klubi cement board A-. The result is as shown in Mr.-3. Also, Awei's {jl discontinuation (
ζ1. It was as shown in ¥NI1-14 figures.

Comparative example 6: 350E/t of salt, sodium hydroxide 15
．． 9/l, temperature 50'C (Figure 11) Comparative example 7: Sodium hydroxide 350.97/=, temperature 2
0C. (Figure 12) Comparative Example 8: Boric acid-free PVA stock solution (PH6'). Saturated bow glass bath. Hot stretching 28 times (Figure 13) Comparative Example 9 PVA stock solution without diboric acid (PH6). Sodium hydroxide 350g/t, temperature 20℃. Hot stretching ratio 3.
3 times (?Jfj14 figure) The fiber obtained in Example 4 shows a slightly higher Young's modulus than the fiber in Comparative Example 6.7. or. The fiber cross section is deformed. The performance of the cement board was better in Example 4.
was. , Reference Examples 1 to 8. Examples 1 and 7c The obtained fibers were each 033 ft'
i%. 0.5 weight chi,. ．． 1 weight chi, 1.5 weight chi, 2
heavy i'chi. 2.5 weight, 0.1 weight, 3 weight. Isamu, Valve 3 weight chi and special clay 1. Contains OM quantity, and the rest is from normal Bolland cent. , a cement laminate was completely formed using a wet paper-making method from the mixture, and then molded at 20°C. Laminated in a humid atmosphere for 28 days. Got the board.

The bending strength and Charby @ impact strength of the obtained laminate were measured. In addition, the dispersibility of fibers during wet papermaking was visually observed and was good (◎). Evaluation was made as good (◯) or slightly poor (△). The results are shown in Table 4.

Based on slate plate, fiber addition fkld0.3
A weight of ~2.5 weight was good, and a weight of 0.5 to 2 weight was particularly good.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the coagulation bath conditions of the present invention. Second
1 evil. tif. Figure a, Figure 7, and Figure 10 respectively show cross-sectional views of the fibers obtained in Examples 1 to 4, and Figure 4.
5, 6, 8, 9, 11, 12, 13, and 14 are Comparative Example 1, respectively. The cross-sectional diagram of the fiber obtained in ~9 is shown. 671

Claims (1)

[Claims] (1) A polyvinyl alcohol-based spinning stock solution to which boric acid or copper salt has been added is prepared under conditions where the caustic alkali concentration (xg/t) and the dehydrating salt concentration (yg7t) are as shown in equations (a)-(b) and (c) below. Spinning into a coagulation bath that simultaneously satisfies 1. /I1 Next, neutralize the conventional method. A method for producing polyvinyl alcohol-based synthetic fibers, which comprises performing wet heat treatment, washing with water, drying, and subjecting to di'f-FC hot stretching. Y≦41.5-1.68X (a) Y≧850-5X (b) Y≧185-0.58X (e)