JPS5828388B2 - Crosslinking method for polymonovinyl aromatic compound fibers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for crosslinking polymonovinyl aromatic compound fibers.

Cross-linked and insolubilized polymonovinyl aromatic compound molded products are useful materials that can serve as base materials for ion exchange resins, ion exchange fibers, ion exchange membranes, and other functional resin molded products, and various methods have been proposed for their production. It has been.

As with ordinary ion exchange resins, the method of copolymerizing polyfunctional monomers during polymerization to make them crosslinked and insolubilized is a conventional method, but this method is limited to applications such as ion exchange resins.

In recent years, a method that has received particular attention is to mold polymonovinyl aromatic compounds into various molded products and then introduce crosslinking groups, but since this is a heterogeneous reaction, it is important to ensure that the reaction is uniform throughout the interior. The success or failure of the method will be determined by whether or not it can be done.

This method includes (1) a method of cross-linking with chlorosulfonic acid, tribasic acid chloride or chloromethyl methyl ether (JP-A-4925223), and (2) a method of cross-linking with formaldehyde (1987-13096).
9) have been proposed, but since method (1) uses highly reactive substances, it is difficult to react uniformly to the inside of the molded product, and it is difficult to suppress side reactions, slow down the reaction, and work safety. There are many problems from this point of view.

On the other hand, method (2) is an excellent method in which the reaction is easy to control, work safety is good, and there is little decrease in mechanical strength of the molded product due to side reactions, but it has the disadvantage of a low reaction rate. However, improvements are required.

The present inventors have arrived at the present invention as a result of intensive studies to find a more excellent method that does not have the above-mentioned drawbacks.

The present invention has the following configuration.

That is, in the present invention, when crosslinking polymonovinyl aromatic compound fibers with a formaldehyde source in the presence of sulfuric acid,
The present invention relates to a method for crosslinking polymonovinyl aromatic compound fibers, which is characterized by treating with a reaction solution containing 10% by weight or less of a formaldehyde source and 0.3 parts or more and 18 parts or less of lower saturated fatty acids per 1 part of sulfuric acid.

The characteristics of the present invention are that, compared to conventional methods, the reaction can be carried out more smoothly under milder conditions, and there is less deterioration in mechanical properties.

The polymonovinyl aromatic compound referred to in the present invention is a vinyl polymer of a monovinyl compound having an aromatic ring such as styrene, α-methylstyrene, vinyltoluene, vinylxylene, p-chlorostyrene, vinylnaphthalene, vinylfluorene, etc., or two types thereof. Vinyl copolymers of these monomers or other vinyl compounds (e.g. ethylene, propylene, vinyl acetate,
It refers to a copolymer made by copolymerizing a small amount of vinyl chloride, methyl acrylate, acrylonitrile, allyl alcohol, vinyl anisole, vinyl acetophenone, etc., or a mixture of these polymers and polyolefin.

In particular, mixing polyolefin at 20 to 90° C. significantly improves mechanical properties, which is practical.

The term "molded product" as used in the present invention means fibers or films, and highly processed products thereof.

If the sulfuric acid concentration in the reaction solution is high, it will induce side reactions and cause a decrease in mechanical strength.On the other hand, if the sulfuric acid concentration is low, the reaction rate will be too slow, so the sulfuric acid concentration is usually 0.
Particularly preferably used is 1 to 80%, especially 1 to 70%.

The optimal range of sulfuric acid concentration also varies depending on the type of polymonovinyl aromatic compound; for example, in the case of polystyrene, it is 50%
Optimal concentration ranges are ~70%, 5-70% for polymers containing vinyltoluene repeating units, and 1-50% for polymers containing vinylxylene repeating units.

As the lower saturated fatty acids used in the present invention, monocarboxylic acids other than acids such as acetic acid, propionic acid, butyric acid, valeric acid, and stearic acid and their halogen-substituted products are preferably used, but they are inexpensive and chemically stable. In terms of properties and operability, C2 to C6 lower fatty acids are particularly preferably used.

In addition, tribasic acids such as adipic acid (excluding oxalic acid)
Although it can also be used, it is considerably inferior in terms of reactivity and stability.

Further, these lower saturated fatty acids can also be used in the form of esters, amides, etc., but these are not so preferred because they involve side reactions.

If the amount of lower saturated fatty acids used is too large compared to the amount of sulfuric acid used, the reaction will be difficult to proceed due to a decrease in catalyst concentration, and the mechanical properties of the fibers will deteriorate; It is preferable to use 0.3 to 18 parts per 1 part of sulfuric acid, since this leads to a decrease in sulfonation and sulfonation due to side reactions.

Furthermore, two or more kinds of lower saturated fatty acids may be mixed.

When water is mixed with the reaction solution, the reactivity decreases, so 3.
It is not preferable to mix 0% or more.

The formaldehyde source used in the present invention is usually formalin, trioxane, tetraoxane, paraformaldehyde, methylal, etc., and is supplied to the reaction solution as a compound that easily generates formaldehyde with an acid.

If the concentration is too low, the reaction rate will be too low, while if it is too high, the reaction solution will be heavily contaminated;
10% is preferably used.

The crosslinking reaction rate in the present invention increases as the processing temperature rises, but if the temperature is too high, the mechanical properties of the molded product will deteriorate sharply and decomposition after the reaction due to side reactions will be promoted. ~110°C, especially 40-95°C
is preferably used.

It is usually most desirable for the crosslinking of the fibers obtained by the method of the present invention to be carried out uniformly throughout the fibers.

The crosslinking rate is defined below as an expression of the degree of crosslinking.

That is, 0.51 sample was immersed in 200 times the volume of toluene,
After shaking at room temperature for 5 hours, the mixture is heated under reflux for 2 hours.

Next, take out the sample while it is hot, wash it with warm toluene, vacuum dry it, and calculate from the weight before and after using the following formula.

In the formula, Wl: Weight of the sample before toluene extraction W2: Weight of the sample after toluene extraction This value will vary depending on the polymer composition of the molded product, even if crosslinking has progressed sufficiently.

For example, if the fiber is made only of polystyrene, the crosslinking rate will be 100% if the crosslinking has progressed sufficiently, but if it is a 1:1 mixture of polypropylene and polystyrene, the polypropylene usually does not participate in the crosslinking reaction. Therefore, even if the polystyrene part is completely crosslinked,
The crosslinking rate should be no more than 50%.

Moreover, in fact, in the method of the present invention, polypropylene is also insolubilized, and the above-mentioned crosslinking rate may be close to 100%.

Therefore, when crosslinking fibers made of a 1:1 mixture of polypropylene and polyvinyl aromatic compound, the crosslinking rate is 50%.
If it exceeds this, it is considered that the crosslinking reaction has progressed sufficiently.

Note that although the crosslinking rate of unreacted yarn is theoretically zero, in practice it may give a value of 0 to 5%.

Examples are shown below.

Example 1 Polypropylene chip (manufactured by Mitsui Toatsu Chemical Co., Ltd., Noblen J
After thoroughly mixing 5 parts of 3HG) and 50 parts of polystyrene chips (Styron 679 manufactured by Asahi Dow), using a plunger-type spinning machine, while cooling the area directly below the spinneret, the spinneret was spun using a 6-hole, 0.5 mmφ spinneret. Temperature 290℃, take-up speed 400 m 7ml yt, discharge speed 5? 7m1y
Melt spinning was carried out at x.

Subsequently, the yarn was drawn 5.6 times in two stages to obtain a drawn yarn of 6 filaments and 20 denier.

The first stage uses a hot plate at 128°C and stretches 3.5 times.
The second stage uses a 116℃ heating pin and a 140℃ heating plate.
．． It was stretched 6 times.

Strength 2.5y'/d, elongation 45%. The above drawn yarn 2.01
was added to 50P of various reaction solutions and reacted under each condition, then
After washing with water and vacuum drying, the crosslinking rate and fiber quality were measured.

Under all conditions, the yarn weight increased or decreased by less than 3% before and after the reaction.

The results are shown in Tables 1 to 4, and comparative examples are also shown at the same time.

* * Table 1 shows the results of studies regarding the types of catalysts.

Pyrophosphoric acid, p-chlorobenzenesulfonic acid and sulfuric acid are found to be particularly effective.

In particular, sulfuric acid is highly active and practical. Table 2 shows the results of a study on the types of lower saturated fatty acids.

Particularly effective are acetic acid, monochloroacetic acid, gropionic acid, and butyric acid.

Table 3 shows the results of a study on the relationship between various reaction conditions, crosslinking rate, and fiber quality.

In the table, the strength and elongation product is the value obtained by dividing the product of strength (P/d) and elongation (%) by 100, and by comparing the values before and after reaction treatment, it is possible to determine the decrease in yarn quality. You can see the extent.

When the acetic acid/sulfuric acid ratio in the reaction solution is 0.34 or more, the strength and elongation product of the crosslinked yarn obtained is the strength and elongation product of the unreacted yarn (i, i)
Although it has hardly decreased since then, it has decreased significantly below 0.1.

When water is used instead of acetic acid, the degree of crosslinking is greatly reduced, and the degree of strength and elongation is also low.

Table 4 shows the results of investigating the effect of adding water to the reaction system, and as the amount of water increases, the degree of crosslinking decreases.

*Example 2 50 parts of polypropylene chips (Noblen J3HG) and styrene/vinyltoluene copolymer chips (styrene content 80% by weight, prepared by bulk polymerization using benzoyl peroxide as a catalyst, μ-2000 poise/250°C) ,
After thoroughly mixing 50 parts of bismetron), the mixture was spun and drawn under exactly the same conditions as in Example 1 to obtain a drawn yarn of 6 filaments and 20 denier.

Strength 25 f/d, elongation 47%. Example 1
The reaction was carried out in the same manner as in Table 5, and the results shown in Table 5 were obtained.

As in Example 1, the effect of using acetic acid is clearly shown in the crosslinking rate.

When the acetic acid/sulfuric acid ratio is 0.098 or less, the strength and elongation product decreases significantly even if the crosslinking reaction progresses.

Example 3 50 parts of polypropylene chips (Noblen J3HG) and styrene/3,5-dimethylstyrene copolymer (styrene content 80% by weight, obtained by bulk polymerization using benzoyl peroxide as a catalyst, μ-1800 poise/ 250℃,
After thoroughly mixing the 5Q portion (bismethron), spinning and drawing were carried out in exactly the same manner as in Example 1 to obtain a drawn yarn of 60 filaments and 20 denier.

Strength 2.6P/d, elongation 49%. Example 1
The reaction was carried out in the same manner as above, and the results shown in Table 6 were obtained.

The effect of the presence of acetic acid in the reaction solution is significant. Example 4 56 parts of polypropylene chips (Noprene J3HG) and 44 parts of polystyrene (Styron 683) were prepared so that the former was an island (16 pieces) and the latter was an ocean, Q, 5 m.
A multi-core composite spinneret with mφ-15 holes was used for melt spinning at 300° C. and a take-up speed of 1000 m1771I71.

Subsequently, the yarn was drawn 5.4 times in the same manner as in Example 1 to obtain a drawn yarn of 15 filaments and 56 denier.

3.5 g/d, elongation 55%. The above drawn yarn was treated in the same manner as in Example 1 to obtain the results shown in Table 7.

The effect of the presence of acetic acid in the reaction solution is significant.

Claims (1)

[Claims] 1. When crosslinking polymonovinyl aromatic compound fibers with a formaldehyde source in the presence of sulfuric acid, 0.1% by weight or less of the formaldehyde source and 1 part of sulfuric acid are used.
A method for crosslinking polymonovinyl aromatic compound fibers, which comprises treating with a reaction solution containing 3 parts or more and 18 parts or less of lower saturated fatty acids.