CN100441754C - Water-soluble polyvinyl alcohol-based fiber and nonwoven fabric containing the fiber - Google Patents

Abstract

The present invention provides a water-soluble PVA-based fiber having practically sufficient fiber properties such as mechanical properties and chemical resistance without impairing the original water solubility, and practically having sufficient mechanical properties, chemical resistance, etc. It is a water-soluble nonwoven fabric that is extremely useful for many purposes, including the base fabric for burnt-out lace. The water-soluble PVA-based fiber of the present invention is characterized in that the compound having an ionic group reacts 0.01-5 mol%, and the relationship between the crystallinity Xcf (%) of the fiber and the dissolution temperature Wtb (° C.) in water satisfies the following formula. The nonwoven fabric of the present invention contains the above-mentioned water-soluble PVA-based fibers. Wtb<2.50·Xcf-70, wherein, 30%≤Xcf≤80%.

Description

Water-soluble polyvinyl alcohol-based fiber and nonwoven fabric containing the fiber

technical field

The present invention relates to water-soluble polyvinyl alcohol (hereinafter abbreviated as PVA)-based fibers and non-woven fabrics containing the fibers, which do not impair the existing water-solubility and have sufficient fiber properties such as mechanical properties and chemical resistance for practical use. The fabric can be used extremely effectively in many applications including the base fabric for chemical lace.

Background technique

In the past, as water-soluble fibers, PVA-based fibers, cellulose-based fibers such as carboxymethyl cellulose, polyalginic acid-based fibers, polyalkylene-based fibers, etc. have been known. Only PVA-based fibers are required for non-woven fabrics such as needle punching, textiles such as weaving, or knitting processes that require excellent mechanical properties and chemical resistance. In addition, in recent years, there is a strong desire to protect the global environment and protect consumers. It is clearly known that PVA-based polymers biodegrade in the natural environment. From the viewpoint of environmental protection, water-soluble PVA-based fibers are expected to become the best fibers.

As the manufacture method of water-soluble PVA-based fiber, for example, it is proposed to use the low-polymerization-degree PVA-based polymer of 200-500 average polymerization degree to improve water solubility, and it is specifically disclosed that it is rapidly dissolved in water below 5° C. (for example, refer to the patent literature 1). However, since the use of a PVA-based polymer with a low degree of polymerization cannot increase the crystallinity of the fiber, the mechanical properties of the fiber are low, and practical use is restricted. Moreover, the fiber contains boric acid or borate, and the waste water used to dissolve and remove the water-soluble fiber contains a large amount of boric acid, requiring a special treatment method and device for treating the substance.

On the other hand, a method is described in which an aqueous solution of a PVA-based polymer with a low degree of saponification is wet-spun in a thick aqueous solution of a salt such as Glauber's salt, followed by stretching at a low draw ratio to obtain A method of dissolving PVA-based fibers below ℃ (for example, refer to Patent Document 2). In addition, it has been proposed to obtain low-temperature soluble PVA-based fibers by dry-wet spinning using a PVA-based polymer with a low degree of saponification, followed by stretching at a low draw ratio (for example, refer to Patent Document 3). In addition, it is proposed to use a PVA polymer with a low degree of saponification and dissolve a solution in an organic solvent such as dimethylsulfoxide (hereinafter referred to as DMSO) for spinning in a curing bath with curing ability such as methanol, thereby obtaining a PVA-based fibers that dissolve in low-temperature water (for example, refer to Patent Document 4). These methods are all achieved by using a PVA-based polymer with a low degree of saponification, which is extremely useful from the viewpoint of imparting low-temperature water solubility, but the crystallinity of the polymer itself is low for a PVA-based polymer with a low degree of saponification , so the crystallinity of the obtained fiber is low, and it is difficult to have mechanical properties necessary for practical use. In addition, in processes such as coagulation and extraction, there are problems such as partial dissolution and adhesion between fibers, and the process passability is not necessarily satisfactory, and further improvement is desired. In addition, although the nonwoven fabric comprising this fiber has excellent low-temperature solubility, its mechanical properties are low, and its practical use is restricted.

On the other hand, when a PVA-based polymer with a high degree of saponification and high degree of polymerization is used, the mechanical properties such as tensile strength are sufficient due to the increase in the crystallinity of the fiber, but the water dissolution temperature becomes 100°C or higher, and water at a low temperature Solubility is impaired. As a method of improving the water solubility of such a PVA-based polymer, for example, by extremely lowering the stretching temperature or the stretching ratio, oriented crystallization is intentionally inhibited, but this method naturally lowers the crystallinity and deteriorates the mechanical properties. The problem.

In addition, for example, when using a PVA-based polymer with a high degree of saponification and a high degree of polymerization for fiberization, it is proposed to simultaneously add a modifier having an atomic group in the molecule capable of reacting with a hydroxyl group present in the PVA-based polymer molecule to the stock solution solvent. , PVA-based fibers provided with various properties including water solubility (for example, refer to Patent Document 5). However, in the method described in Patent Document 5, fiber crystallinity decreases due to excessive reaction at the dope stage, and only fibers with low mechanical properties such as water solubility and tensile strength can be obtained. In addition, unreacted substances are mixed into the recovery system, and there are problems such as requiring a special treatment method and process for treating them.

In addition, in the field of water-soluble nonwoven fabrics such as the base fabric for burnt-out lace using water-soluble PVA-based fibers, in addition to the so-called high-temperature dissolution type that can be dissolved in water above 80°C, which was required in the past, recently due to its market Due to the diversification of needs, there are also so-called medium-temperature soluble non-woven fabrics that can be dissolved in water at 40-80°C, and so-called low-temperature soluble non-woven fabrics that can be dissolved near room temperature. For example, in the case of embroidery with slim designs, the weft density (count density) increases, and the dissolution after embroidery becomes difficult. In addition, in the case of high-end embroidery using silk or acetate, etc., the thermal stability of the material itself is low. , for these and other reasons, it is desired to develop nonwoven fabrics using fibers that dissolve at lower temperatures. On the other hand, water-soluble nonwoven fabrics are also desired to have both mechanical properties including strength and elastic modulus in order to prevent pattern mispatterning and damage to the nonwoven fabric during embroidery under high tension.

In order to develop non-woven fabrics using fibers that can be dissolved at lower temperatures, non-woven fabrics using PVA-based fibers with a low degree of saponification have been proposed (for example, refer to Patent Document 6), but due to the use of PVA-based polymers with a low degree of saponification , so that the crystallinity of the fiber cannot be increased, so although the nonwoven fabric containing the fiber has excellent low-temperature solubility, its mechanical properties are low, and its practical use is restricted.

On the other hand, in order to improve the mechanical properties of non-woven fabrics, non-woven fabrics made of fibers made of PVA-based polymers with a high degree of saponification and a high degree of polymerization as raw materials increase the crystallinity of the fibers, so the tensile strength, etc. The mechanical properties are sufficient, but the water dissolution temperature becomes 120° C. or higher, and the water solubility at low temperature is impaired. As a method of improving water solubility using such a PVA-based polymer, for example, by extremely lowering the stretching temperature or the stretching ratio, thereby deliberately inhibiting the orientation crystallization, but this method naturally lowers the crystallinity, and the fiber composed of such Nonwoven fabrics have a problem that mechanical properties are impaired.

[Patent Document 1] JP-A-3-199408

[Patent Document 2] JP-A-53-045424

[Patent Document 3] JP-A-5-086503

[Patent Document 4] Japanese Unexamined Patent Publication No. 7-042019

[Patent Document 5] JP-A-2000-136430

[Patent Document 6] JP-A-11-217759

Contents of the invention

As mentioned above, in the past, the water solubility of PVA-based fibers can be given by controlling the degree of polymerization or saponification of the PVA-based polymer used, or the stretching conditions, but any method will reduce the crystallinity of the fiber. There are problems such as lowering of mechanical properties, and there are also problems in terms of process passability and cost. Therefore, it is desired to develop a water-soluble PVA-based fiber and a water-soluble nonwoven fabric containing the fiber, which have both water-solubility properties and mechanical properties including tensile strength, and which have good process passability and are inexpensive.

In order to obtain the above-mentioned water-soluble PVA-based fibers and non-woven fabrics containing the fibers, the present inventors have repeatedly studied assiduously. As a result, they have found that no special process is required for PVA-based polymers. By reacting the compound with the fiber in the subsequent process, a highly crystalline water-soluble PVA-based fiber having excellent mechanical properties can be produced inexpensively without impairing the existing water solubility. In addition, it was found that when the dissolution temperature in water of the water-soluble nonwoven fabric made of the fiber is in a specific relationship with the degree of crystallinity used as an index of mechanical properties, it is possible to obtain a non-woven fabric having excellent water solubility properties and mechanical properties that cannot be realized in the prior art. Water-soluble non-woven fabric, thus completed the present invention.

That is, the present invention is a water-soluble PVA-based fiber, which is characterized in that it is formed by reacting with 0.01-5 mol% of a compound having an ionic group, and the crystallinity Xcf (%) of the fiber and the water dissolution temperature Wtb (° C.) The relationship satisfies the following formula (I),

Wtb＜2.50Xcf-70 ...(I)

Among them, 30%≤Xcf≤80%.

Next, the present invention is the aforementioned water-soluble PVA-based fiber, wherein the compound having an ionic group is preferably glyoxylic acid or a neutralized product of glyoxylic acid.

In addition, the present invention relates to a method for producing the above-mentioned water-soluble PVA-based fibers, which comprises dissolving a PVA-based polymer having a degree of polymerization of 1000-4000 and a degree of saponification of 88 mol% or more in an organic solvent, and using the obtained spinning stock solution with the polymer Wet or dry-wet spinning is carried out in a curing bath mainly composed of an organic solvent with curing ability, and then passed through an extraction bath in which 1-50 g/l of a compound having an ionic group is dissolved, and the fiber is impregnated with the compound , react and introduce in any one of the steps of drying, stretching, and heat treatment, and at the same time, make the total stretching ratio of all the steps be 3 times or more.

In addition, the present invention is a water-soluble nonwoven fabric comprising the above-mentioned water-soluble PVA-based fibers, and the relationship between the degree of crystallinity Xcw (%) of the nonwoven fabric and the dissolution temperature SP (°C) in water satisfies the following formula (II): ,

SP＜2.50Xcw-50 ...(II)

Among them, 30%≤Xcw≤65%.

In addition, the present invention is the above-mentioned water-soluble nonwoven fabric, characterized in that the relationship between the elastic modulus M (N/50mm) of the nonwoven fabric and the dissolution temperature SP (°C) in water satisfies the following formula (III),

SP＜1.60M-22 ...(III)

Among them, 30N/50mm≤M≤80N/50mm.

According to the present invention, it is possible to provide water-soluble PVA-based fibers that have both water-solubility properties and mechanical properties including tensile strength, which cannot be achieved in the prior art. In addition, the water-soluble PVA-based fiber of the present invention does not require a special process, and can be realized by ordinary spinning and drawing processes, and can be produced at low cost. The water solubility of the water-soluble PVA-based fibers of the present invention can be appropriately controlled, and when the dissolution temperature in water of the water-soluble nonwoven fabric using the fibers has a specific relationship with the degree of crystallinity used as an index of mechanical properties, existing Water-soluble non-woven fabrics that have both water-solubility and mechanical properties, which cannot be realized by technology, are extremely useful in many applications, including base fabrics for burnt-out lace.

Description of drawings

Fig. 1 shows the water-soluble PVA-based fibers of the present invention, the water-soluble fibers described in JP-A-7-42019 and JP-A-7-90714, and various types of Solvron manufactured by Nitivy. Plot of dissolution temperature in water (Wtb) versus crystallinity of fibers (Xcf).

Fig. 2 shows the non-woven fabric comprising the water-soluble PVA-based fiber of the present invention, and the non-woven fabric comprising the PVA-based water-soluble fiber described in JP-A-7-42019 and JP-A-7-90714, and the non-woven fabric comprising A graph showing the relationship between the dissolution temperature SP (° C.) in water and the crystallinity Xcw (%) of the nonwoven fabric of various types of sheets of Solvron manufactured by Nitivy.

Fig. 3 shows the non-woven fabric comprising the water-soluble PVA-based fiber of the present invention, and the non-woven fabric comprising the PVA-based water-soluble fiber described in JP-A-7-42019 and JP-A-7-90714, and the non-woven fabric comprising A graph showing the relationship between the dissolution temperature SP (° C.) in water and the elastic modulus M (N/50 mm) of the nonwoven fabric of various types of Solvron sheets manufactured by Nitivy.

Detailed ways

The present invention will be specifically described below. The degree of polymerization of the PVA-based polymer used in the present invention is preferably 1000-4000 based on the viscosity of an aqueous solution at 30° C. in consideration of the mechanical properties, dimensional stability, and water solubility properties of the fibers obtained. When a PVA-based polymer having an average degree of polymerization exceeding 4000 is used, although excellent in mechanical properties, water solubility properties such as large shrinkage during dissolution may be impaired. In addition, when using a PVA-based polymer with an average degree of polymerization lower than 1000, the obtained fiber has low crystallinity, so not only the mechanical properties are insufficient, but also the polymer is caused in the fiber manufacturing process such as coagulation and extraction. Dissolution can easily cause adhesion between fibers. The average degree of polymerization is more preferably 1500-3500.

The degree of saponification of the PVA-based polymer used in the present invention is not particularly limited, but is preferably 88 mol% or more in terms of the crystallinity and water solubility of the obtained fiber. When using a PVA-based polymer with a saponification degree of less than 88 mol%, since the crystallinity is extremely reduced, it is preferable to impart water solubility at low temperature, but the mechanical properties and process of the obtained fiber are limited. It is not preferable in terms of performance, manufacturing cost, and the like.

In addition, the PVA-based polymer forming the fiber of the present invention is not particularly limited as long as it is mainly composed of vinyl alcohol units. As long as the effect of the present invention is not impaired, it may also contain ethylene, vinyl acetate, coating Constituent units such as conic acid, vinylamine, acrylamide, vinyl pivalate, maleic anhydride, and vinyl compounds containing sulfonic acid. However, in order to obtain the fiber for the purpose of the present invention, it is more preferable to use a polymer having a vinyl alcohol unit of 88 mol%. Of course, additives such as antioxidants, antifreezing agents, pH adjusters, masking agents, colorants, and oil agents may be contained in the polymer according to the purpose within the range that does not impair the effects of the present invention.

The water-soluble PVA-based fiber of the present invention is obtained by impregnating the compound having an ionic group in the fiber at the raw fiber stage, and reacting and introducing the compound in the subsequent process. The water solubility characteristics of the water-soluble PVA-based fibers of the present invention obtained in this way are expressed by the temperature at which the fibers dissolve, which will be described later. Depending on the type of polymer, the type of compound having an ionic group, and the reaction to the PVA-based polymer The degree of neutralization of ionic groups can be controlled over a wide temperature range.

The compound having an ionic group used in the present invention is not particularly limited as long as it reacts with the hydroxyl group in the PVA-based polymer, and examples thereof include aldehydes, epoxies, carboxylic acids, isocyanates, and silanes. Alcohols, etc. In addition, as such an ionic group, for example, carboxylic acid or sulfonic acid, or a part or all of these neutralized products, etc., are not particularly limited. Among them, carboxylic acids or their neutralized products are preferred from the viewpoint of cost and availability, and especially compounds having metal neutralized products of carboxylic acids are preferred when water solubility at lower temperatures is to be imparted. Among them, glyoxylic acid or a metal neutralized product thereof is particularly preferable from the viewpoint of reactivity with fibers, control of water solubility, and mechanical properties.

For example, when glyoxylic acid is reacted with a PVA-based polymer to introduce the compound, a carboxylic acid can be introduced into the molecular chain of PVA. Carboxylic acid anions have a large steric hindrance, and carboxylic acid anions repel each other, so the network of molecular chains expands to form a state that is easier to absorb water. As a result, the absorption speed of water is fast, so the water solubility at lower temperature is excellent. At this time, if a metal with a high ionization tendency such as sodium is used to neutralize the carboxylic acid site introduced into the molecular chain, the carboxylate anion is generated faster, and the water absorption rate can be increased. fiber.

The metal species used to neutralize ionic groups is not particularly limited, and examples thereof include sodium, calcium, and magnesium, among which metals such as sodium that tend to ionize are preferred. In addition, the neutralization method is not particularly limited, and a known method can be employed. For example, a compound having a carboxylic acid group is dissolved in an extraction solvent, and sodium hydroxide or the like is added thereto to neutralize the carboxylic acid with sodium ions. In addition, the degree of neutralization can be controlled by the amount of metal ions added at this time.

In the water-soluble PVA-based fiber of the present invention, it is necessary to react 0.01 to 5 mol% of the above-mentioned compound having an ionic group. When the reactivity of the compound having an ionic group in the water-soluble PVA-based fiber of the present invention is less than 0.01 mol%, the water-soluble fiber targeted by the present invention cannot be obtained. becomes lower, so the mechanical properties of the obtained fiber become lower, and problems such as significant shrinkage during dissolution occur. The degree of reactivity is preferably 0.05-4 mol%, more preferably 0.08-3 mol%. In addition, in the water-soluble PVA-based fiber of the present invention, the reactivity of the compound having an ionic group is measured by the method described below.

In addition, the water-soluble PVA-based fiber of the present invention is characterized in that it is excellent in mechanical properties including tensile strength despite being a water-soluble fiber. That is, it is important that the relationship between the dissolution temperature Wtb (° C.) in water and the degree of crystallinity Xcf (%), which is an index for improving the mechanical properties of the fiber, is expressed by the following formula (I),

Wtb＜2.50Xcf-70 ...(I)

Among them, 30%≤Xcf≤80%.

In the past, the control of water solubility in water-soluble fibers based on the degree of polymerization, degree of saponification, stretching conditions, etc., sacrificed the crystallization of fibers, so water-soluble fibers with both mechanical properties could not be obtained. Fig. 1 is for the water-soluble PVA fiber of the present invention, and the water-soluble fiber described in JP-A-7-42019 and JP-A-7-90714, and the water-soluble fiber currently on the market [Nitivy Co., Ltd. "Solvron"], a graph showing the relationship between the dissolution temperature in water and the degree of crystallinity of each. As for "Solvron", there are SS, SU, SX and SL as varieties, and they are indicated by white circles, and those described in JP-A-7-42019 and JP-A-7-90714 are indicated by white squares The water-soluble fibers of the present invention are represented by black circles (Example), and the comparative examples are represented by black squares. As shown in FIG. 1, in "Solvron" or the water-soluble fibers described in JP-A-7-42019 and JP-A-7-90714, the water dissolution temperature Wtb (°C) and crystallinity The relationship of Xcf (%) can be roughly expressed by a straight line, and its relationship is expressed by the following formula (IV),

Wtb＞2.50·Xc-58 …(IV)

Among them, 30%≤Xc≤80%.

The details are illustrated by examples. The water-soluble PVA-based fibers of the present invention are all within the range of formula (I) (the hatched part in the figure), and compared with the conventional water-soluble fibers, they can obtain high crystallinity, that is, mechanical properties. Excellent water soluble fiber. Among them, when the degree of crystallinity Xcf is less than 30%, the mechanical properties of the obtained fiber are low, and when the degree of crystallization Xcf exceeds 80%, Wtb becomes 120°C or higher, neither of which satisfies the object of the present invention. In addition, the dissolution temperature Wtb (°C) in water and the degree of crystallinity Xcf (%) referred to in the present invention are measured by the method described later.

Although it is unclear why the water-soluble PVA-based fiber of the present invention has a high degree of crystallinity despite being water-soluble, the present inventors speculate as follows.

It is presumed that by introducing a compound having an ionic group into the fiber, the melting point of the fiber itself is slightly lowered, so that when the compound is not introduced, the actual stretching conditions are different. Therefore, it is presumed that in the present invention, stretching is performed at a temperature closer to the melting point. That is, it is presumed that in the present invention, stretching is performed in a state of higher molecular mobility, and orientation crystallization is promoted, thereby obtaining fibers with high crystallinity.

The fineness of the fibers obtained by the present invention is not particularly limited, for example, fibers with a fineness of 0.1-10000 dtex, preferably 1-1000 dtex, can be widely used. The fineness of the fiber can be appropriately adjusted by the diameter of the nozzle or the draw ratio.

Next, a method for producing the water-soluble PVA-based fiber of the present invention will be described. In the present invention, by using a spinning stock solution in which a PVA-based polymer is dissolved in water or an organic solvent, and producing fibers by the method described later, it is possible to efficiently and inexpensively produce fibers with high crystallinity, excellent mechanical properties, and excellent water solubility. of fiber. As the solvent constituting the spinning dope, for example, polar solvents such as dimethylsulfoxide (hereinafter abbreviated as DMSO), dimethylacetamide, dimethylformamide, N-methylpyrrolidone, glycerin, ethylene glycol, etc. Polyols, their mixtures with thiocyanate, lithium chloride, calcium chloride, zinc chloride and other swelling metal salts, and these solvents, or the mixture of these solvents and water, among the above solvents Among them, water or DMSO is most preferable in terms of process passability such as cost and recyclability.

The polymer concentration in the spinning dope varies depending on the composition, degree of polymerization, and solvent, but is preferably in the range of 8 to 40% by mass. The liquid temperature when the spinning dope is ejected is preferably within the range where the spinning dope does not decompose or color, specifically, it is preferably 50-150°C.

Such a spinning stock solution may be sprayed from a nozzle for wet spinning or dry-wet spinning, and it may be sprayed to a solidifying solution capable of curing PVA-based polymers. In addition, wet spinning is a method in which the spinning stock solution is directly sprayed from the spinning nozzle to the solidification bath. The silk stock solution is then introduced into the curing bath.

The curing bath used in the present invention is different when the stock solution solvent is an organic solvent and when it is water. In the case of using a stock solution of an organic solvent, a mixed liquid composed of a solidification bath solvent and a stock solution solvent is preferable from the viewpoint of the obtained fiber strength and the like. The solidification solvent is not particularly limited, and for example, methanol, ethanol, propanol, and butanol can be used. Organic solvents such as alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone and other ketones that have the ability to cure PVA polymers. Among these solvents, a combination of methanol and DMSO is preferable in terms of low corrosivity and solvent recovery. On the other hand, when the spinning stock solution is an aqueous solution, an aqueous solution of inorganic salts such as mirabilite, sodium chloride, and sodium carbonate capable of curing PVA-based polymers can be used as the curing solvent constituting the curing bath.

Secondly, in order to extract and remove the solvent of the spinning dope from the solidified precursor, make it pass through the extraction bath, on the basis of suppressing the adhesion between the fibers during drying and improving the mechanical properties of the obtained fibers, it is preferable to extract it at the same time. Wet drawn strands. The wet draw ratio at this time is preferably 2 to 6 times in view of processability and productivity. As the extraction solvent, a solidification solvent alone or a mixture of a stock solution solvent and a solidification solvent can be used.

After wet stretching, the fibers may be dried or stretched to produce PVA-based fibers. To obtain the fibers of the present invention, they are passed through an extraction bath in which a compound having an ionic group is dissolved, and the fibers are impregnated with the compound. In this case, the fiber is preferably swollen by the extraction solvent in the extraction bath from the viewpoint of uniform penetration of the compound having an ionic group into the fiber. Therefore, the extraction solvent is preferably alcohol such as methanol or water. That is, in the spinning process, after the fibers are sufficiently crystallized, the fibers in a swollen state are impregnated with the compound in the extraction solvent, and reacted and introduced through the subsequent steps of drying, stretching, heat treatment, etc., Thereby, a PVA-based fiber having both mechanical properties such as tensile strength and water solubility can be obtained without lowering the substantial draw ratio.

On the other hand, when a modifying agent containing an atomic group such as an aldehyde group or an ester group that easily reacts with the hydroxyl group of the PVA-based polymer is added from the stock solution, the reaction proceeds at this stage, and crystallization during the curing process is hindered. , the subsequent drawability decreases, and as a result, the crystallinity decreases, so only fibers with low mechanical properties can be obtained. In addition, when a compound obtained by reacting a compound having an ionic group and a PVA-based polymer is used as a raw material, the crystallinity of the obtained fiber is also low, so only a fiber with low mechanical properties can be obtained. In addition, the method of applying the compound by roller touch or the like after stretching or heat treatment cannot be applied in a sufficient amount, and it cannot be impregnated uniformly in the fiber, and the reproducibility is lacking. Therefore, as described above, it is preferable to impregnate the PVA-based fibers in a swollen state in the extraction solvent with the compound.

In the water-soluble PVA-based fiber of the present invention, as described above, the water dissolution temperature can be appropriately controlled by the amount of the compound having an ionic group introduced. The amount of the compound having an ionic group added to the extraction bath may be appropriately set according to the required water solubility properties, and is preferably in the range of 1 to 50 g/l. When the amount added is less than 1 g/l, the water solubility properties aimed at by the present invention cannot be obtained. In addition, when it exceeds 50 g/l, the reaction proceeds excessively, the degree of crystallinity decreases, and mechanical properties decrease or shrink in water, so it is not preferable. More preferably 2-30 g/l.

In this way, the compound introduced into the fiber during the spinning process from solidification to extraction can be reacted by heat in any process of drying after spinning, stretching, and heat treatment, thereby making it possible to produce the water-soluble fiber of the present invention. PVA-based fibers. The temperature at the time of drying, stretching, and heat treatment required for the reaction is not particularly limited, but it is preferably in the range of 100 to 240° C. considering that the reaction is carried out simultaneously with stretching for expressing the mechanical properties of the fiber. When the temperature is lower than 100° C., the reaction becomes difficult to proceed, and at the same time, the fibers are whitened, resulting in a decrease in mechanical properties. Moreover, when it exceeds 240 degreeC, melting of a fiber part will generate|occur|produce, and also in this case, mechanical physical property will fall, and it is unpreferable. More preferably, it is in the range of 120-220°C.

The water-soluble PVA-based fiber of the present invention preferably has a total draw ratio of 3 times or more. When the draw ratio is less than 3 times, the mechanical properties of the fiber are impaired. In addition, the draw ratio mentioned here is the product of the said wet stretch in the curing bath before drying and the draw ratio after drying. For example, when the wet stretching is 3 times and the subsequent stretching is 2 times, the total stretching ratio is 6 times.

The water-soluble PVA-based fibers of the present invention can be used in forms such as staple fibers, filaments, spun yarns, knots, ropes, and fibrils, for example. Moreover, using this fiber, for example, nonwoven fabrics, knitted fabrics, etc. can also be produced, and it is more preferable to produce nonwoven fabrics such as base fabrics for burnt-out lace in applications requiring water solubility.

For a water-soluble nonwoven fabric composed of the above-mentioned water-soluble PVA-based fibers, the relationship between the dissolution temperature SP (° C.) of the nonwoven fabric in water and the degree of crystallinity Xcw (%) used as an index of mechanical properties is expressed by the following formula (II): When , not only excellent in water solubility, but also excellent in mechanical properties including tensile strength and modulus of elasticity.

SP＜2.50Xcw-50 ...(II)

Among them, 30%≤Xcw≤65%.

As described above, in the past, the water-soluble properties and mechanical properties of water-soluble nonwoven fabrics were controlled by changing the specifications of the water-soluble PVA-based fibers used. For example, when it is desired to obtain a water-soluble nonwoven fabric excellent in low-temperature solubility, a PVA-based polymer with a low degree of polymerization or saponification can be used as a raw material, or a water-soluble PVA-based fiber obtained by controlling stretching conditions and the like can be used. That is, by reducing the crystallinity of the fibers used, water-soluble properties are imparted. However, in such a conventional method, the crystallinity of the fibers is low, and the water-soluble nonwoven fabric manufactured using the fibers is excellent in water-soluble properties, but cannot be obtained. Water-soluble nonwoven fabric that meets mechanical properties. Fig. 2 is for the water-soluble nonwoven fabric of the present invention, and the nonwoven fabric (comparative example) made of water-soluble PVA-based fibers described in JP-A No. 7-42019 and JP-A No. 7-90714, and Tablets of currently marketed water-soluble fibers ["Solvron" manufactured by Nitivy Co., Ltd.] are graphs showing the relationship between the dissolution temperature in water and the degree of crystallinity of each sheet. As for "Solvron", there are SS, SU, SX, and SL as varieties, and the sheets containing them are indicated by white circles, and the sheets containing JP-A-7-42019 and JP-A-2 are indicated by white squares. The nonwoven fabrics of water-soluble fibers described in Publication No. 7-90714, and the nonwoven fabrics of the present invention (Example) are indicated by black circles. As shown in FIG. 2 , in a sheet-like material containing "Solvron" or a water-soluble nonwoven fabric described in JP-A No. 7-42019 and JP-A-7-90714, it dissolves in water. The relationship between temperature SP (°C) and crystallinity Xcw (°C) can be roughly represented by a straight line, and the relationship is represented by the following formula (V),

SP＞2.50Xcw-39 ...(V)

Among them, 30%≤Xcw≤65%.

As shown in Figure 2, the water-soluble non-woven fabric of the present invention is all in the scope of formula (II) (hatched part in the figure), compared with the water-soluble non-woven fabric in the past, it is characterized in that even if the dissolution temperature in water is the same, The degree of crystallinity is also high. Here, when the crystallinity Xcw is less than 30%, the mechanical properties of the obtained nonwoven fabric are low. For example, when used as a base fabric for burnt-out lace, the nonwoven fabric is damaged or mispatterned during embroidery ), etc., the actual use is restricted. In addition, when the crystallinity Xcw exceeds 65%, the melting temperature SP reaches 120°C or more. In addition, in the case of high-grade embroidery using raw materials such as silk or acetate, problems such as deterioration of raw materials such as silk or acetate occur due to the low thermal stability of the raw material itself, which do not meet the purpose of the present invention. In addition, the dissolution temperature SP (°C) in water and the degree of crystallinity Xcw (%) referred to in the present invention are measured by the method described later.

Fig. 3 shows the relationship between the elastic modulus M (N/50 mm) of the nonwoven fabric used in Fig. 2 and the dissolution temperature SP (° C.) in water. As shown in Fig. 3, in the water-soluble nonwoven fabric containing the sheet of Solvron (Solvron), or the fibers described in JP-A No. 7-42019 and JP-A-7-90714, elastic The relationship between the modulus M and the dissolution temperature SP in water can be roughly represented by a straight line, and its relational formula is represented by the following formula (VI),

SP＞1.60M-4.0 ...(VI)

Among them, 30N/50mm≤M≤80N/50mm.

As shown in Figure 3, the water-soluble non-woven fabrics of the present invention are all within the range of formula (III) (hatched parts in the figure), compared with the conventional water-soluble non-woven fabrics, the feature is that even if the melting temperature is the same, the elasticity The modulus is also high. This is considered to be due to the high crystallinity of the nonwoven fabric as shown in FIG. 2 . Here, when the elastic modulus M is lower than 30N/50mm, for example, when used as a base fabric for burnt-out lace, the non-woven fabric is damaged during embroidery, or mispatterning occurs, and the actual use is restricted. In addition, when the elastic modulus M exceeds 80N/50mm, the dissolution temperature SP inevitably reaches 110°C or higher, and in the case of embroidery with a slim design, the weft density (count density) increases, and the dissolution after embroidery becomes difficult. In addition, In the case of high-end embroidery using raw materials such as silk or acetate, since the thermal stability of the raw material itself is low, problems such as deterioration of raw materials such as silk or acetate occur, and neither satisfies the purpose of the present invention. In addition, the elastic modulus M (N/50mm) was measured by the method mentioned later.

The method for producing the water-soluble nonwoven fabric of the present invention is not particularly limited, and conventionally known methods can be used. Concretely, there may be mentioned a combination with a needle punching method, an embossing method, a foam bonding method, a heating method (embossing, hot air, mold forming) mixed with thermally fused fibers, an adhesive bonding method, a water flow method, etc. Non-woven fabrics produced by complexing, melt-blowing or spun-bonding, or combinations thereof, can be appropriately selected according to the quality of the non-woven fabric. For example, the single fiber tow of the water-soluble PVA-based fiber obtained as described above is opened or crimped by the repulsion generated by triboelectric charging, and the cut chemical fiber staple fiber is opened with a carding machine to form a fiber web. The fiber web uses a hot embossing roll with a crimping area ratio of 3-50%, at a temperature 20-100°C lower than the melting point of the water-soluble PVA-based fiber constituting the fiber web, with a line thickness of 3-100kg/cm By thermocompression bonding, a water-soluble nonwoven fabric can be obtained. At this time, when the pressure bonding ratio of the heat embossing roll is less than 3%, the pressure bonding area is small, and the mechanical properties of the nonwoven fabric become insufficient. When it exceeds 50%, the pressure bonding area is large, the texture is hard, and wrinkles tend to occur. The crimping ratio of the emboss roll is preferably 5-40%, more preferably 10-30% from the viewpoint of mechanical properties and texture. When the melting point of the water-soluble PVA-based fibers forming the fiber web is denoted as Tm, if the thermocompression bonding temperature is higher than (Tm-20°C), the crimping property will be improved, and a nonwoven fabric with excellent mechanical properties will be obtained, but water soluble properties are compromised. In addition, when the crimping temperature is lower than (Tm-100° C.), thermocompression bonding becomes insufficient and mechanical properties are impaired. Therefore, the thermocompression bonding temperature is preferably (Tm-20°C) to (Tm-100°C). When the crimping ratio is high, it is preferable to lower the thermocompression bonding temperature, and to increase the thermocompression bonding temperature otherwise. In addition, the thermocompression bonding temperature mentioned here is the temperature of the nonwoven fabric itself, not the temperature of the embossing roll. When the speed of the embossing roll is low, the temperature of the nonwoven fabric and the roll are almost the same, but when the embossing roll is rotated at a high speed, heat conduction becomes insufficient, and the temperature of the nonwoven fabric may drop. When the linear pressure is less than 3 kg/cm, the cross-section of the fibers in the thermocompression bonded portion is not sufficiently flat, and the bonded area is not large, so the strength of the nonwoven fabric becomes insufficient. When thermocompression bonding is performed with a linear pressure exceeding 100 kg/cm, it is not preferable because the crimped fibers themselves are damaged, cracks are generated near the embossed points, holes are opened, and mechanical properties are lowered. The linear pressure is preferably 10-80 kg/cm, more preferably 15-40 kg/cm in view of the mechanical properties of the nonwoven fabric. From the perspective of the overall performance of the nonwoven fabric, it is preferable to increase the line pressure when the crimping ratio is small or when the crimping temperature is lowered, and to reduce the line pressure in the opposite case.

The content of the water-soluble PVA-based fibers of the present invention in the nonwoven fabric is preferably 5 to 100% by mass. When the content is less than 5% by mass, it becomes difficult to use it in applications requiring water solubility. In addition, since the water-soluble PVA-based fiber of the present invention has fiber physical properties such as thermocompression bonding and sufficient strong elongation, it can be pressed by using 100% by mass of the water-soluble PVA-based fiber of the present invention in a nonwoven fabric. flower processing or acupuncture processing. However, it can also be used in combination with other fibers depending on the desired quality and cost. For example, natural fibers such as pulp and cotton, rayon, recycled fibers such as cupra, acetate, and promix can also be used together. Synthetic fibers such as semi-synthetic fibers, polyester fibers, acrylic fibers, polyamide fibers (nylon, aramid, etc.), water-insoluble PVA fibers, etc. are mixed or laminated. In addition, the nonwoven fabric containing the water-soluble PVA-based fiber of the present invention can also be composited with other materials such as films, metals, resins, etc. as needed.

For the pattern of the water-soluble nonwoven fabric of the present invention, since the required performance is different depending on the application, there is no special limitation, and the existing well-known square rhombus pattern, deformed square pattern, fine point pattern, weaving pattern, etc. can be suitably used according to the purpose. pattern etc.

The present invention will be described in more detail below in conjunction with examples, but the present invention is not limited by these examples. In addition, in the following examples, the reactivity of the ionic compound in the fiber, the dissolution temperature in water of the fiber, the tensile strength of the fiber, the dissolution temperature in water of the non-woven fabric, the dissolution temperature of the fiber in water, the non-woven fabric and the fiber The crystallinity of and the modulus of elasticity of the nonwoven fabric represent values measured by the following method.

[Mole % of reactivity of ionic compound in fiber]

The measurement of the reactivity was carried out using a nuclear magnetic resonance apparatus (NMR) manufactured by JEOL Ltd. Dissolve PVA fibers in a DMSO solution at a solution temperature of 50 to 140°C. Using ¹³ C-NMR, the peak (chemical shift = 100 ppm) attributed to the structure (acetal) generated by the reaction and the _CH2 group in PVA Calculate the peak area ratio.

[Crystallinity (Xcf, Xcw)% of fiber and nonwoven fabric]

The total melting enthalpy (ΔH _obs ) of the sample was measured using a Pyris-1 differential scanning calorimeter manufactured by Perkin Elmer. The measurement conditions were a heating rate of 80° C./minute, and the mass crystallinity was calculated from the following formula. In addition, correction of the melting point and heat of fusion was performed using indium and lead as standard substances.

Xcf, Xcw (%) = ΔH _obs / ΔH _cal × 100

ΔH _obs : Measured total heat of fusion (J/g)

ΔH _cal : heat of fusion of complete crystallization (174.5J/g)

[Water dissolution temperature of fiber (Wtb)°C]

Hang a fiber sample with a specified load (2mg/dtex) in ice water set at a temperature of 3°C, raise the water temperature at a rate of 2°C/min, and measure the water temperature until the sample breaks and the load drops. The relationship between the shrinkage rate and the temperature at the time of the load drop is expressed as Wtb.

[Fiber strength cN/dtex]

According to JIS L1013, under the conditions of test length 20cm, initial load 0.25cN/dtex and tensile speed 50%/min, measure the pre-conditioned yarn, and use the average value of n=20. In addition, the fiber fineness (dtex) was obtained by the mass method.

[Solution temperature (SP)°C of nonwoven fabric in water]

3 pieces of non-woven fabric sheets cut into 2 cm squares were dropped into 400 cc of water, and the temperature was raised while stirring at a heating rate of 3° C./min and a stirring rate of 280 rpm, and the temperature at which the fibers were completely dissolved was measured as the dissolution temperature in water.

[Non-woven elastic modulus (M) N/50mm]

Collect two kinds of samples of the non-woven fabric along the orthogonal direction, which are rectangles with a width of 5 cm and a length of 15 cm. Use the automatic plotter of the tensile testing machine made by Shimadzu to test the length of 10 cm, the initial load of 0.25 cN/dtex and the tensile speed. The measurement was performed under the condition of 100%/min, and the average value of values obtained by normalizing the tensile force at the time of elongation of 50 mm by the weight per unit area of 40 g/cm ² was used.

[Example 1]

(1) PVA having a viscosity average degree of polymerization of 1700 and a degree of saponification of 96.0 mol % was added to DMSO so that the PVA concentration was 23% by mass, and dissolved by heating at 90° C. under a nitrogen atmosphere. The obtained spinning stock solution was passed through a nozzle with a hole diameter of 0.08 mm and a number of holes of 108, and dry-wet spinning was carried out in a solidification bath composed of methanol/DMSO=70/30 (mass ratio) at a liquid temperature of 5°C.

(2) The obtained cured yarn was immersed in a second bath having the same methanol/DMSO composition as the curing bath, and then wet stretched three times in a methanol bath at a liquid temperature of 25°C. Thereafter, it was immersed in a methanol bath (extraction bath) in which 10 g/l of glyoxylic acid manufactured by Wako Pure Chemical Industries, Ltd. was dissolved, and then dried with hot air at 120° C. to obtain a spinning yarn. Next, the obtained spinning strand was stretched in a hot-air drawing furnace at 160° C. so that the total draw ratio (wet draw ratio×hot-air furnace draw ratio) was 6 times. The performance evaluation results of the obtained fibers are shown in Table 1.

(3) The reactivity of glyoxylic acid in the obtained fiber was 0.9 mol%. In addition, the fiber physical properties of the obtained fiber were: monofilament fineness 2.0 dtex, fiber crystallinity Xcf = 38%, water dissolution temperature Wtb = 20°C, and fiber strength 7.5 cN/dtex.

(4) From the above (3), it can be seen that the relationship between the crystallinity Xcf of the fiber and the dissolution temperature Wtb of the fiber in water satisfies the condition of formula (I), and the appearance of the fiber is good, without silk spots, etc. excellent.

(5) crimping, cutting the above-mentioned obtained fiber, making chemical fiber short fiber, carding and making fiber web, setting the embossing roll of the square rhombus lattice pattern of crimping area ratio 25% at 180 ℃, with speed 10m/ The fibrous web was subjected to hot embossing treatment at a point and line pressure of 40kg/cm. Table 3 shows the evaluation results of the obtained nonwoven fabric.

(6) The weight per unit area of the obtained non-woven fabric is 40g/cm ² , the dissolution temperature in water SP=61°C, the degree of crystallinity Xcw=45%, the modulus of elasticity M=43N/50mm, the dissolution temperature SP of the non-woven fabric and The relationship of the crystallinity Xcw of the non-woven fabric satisfies the condition of formula (II), and the relationship between the dissolution temperature SP of the non-woven fabric and the modulus of elasticity M of the non-woven fabric satisfies the condition of the formula (III), and the solubility and mechanical properties excellent.

(7) The nonwoven fabric obtained in the above (5) was further embroidered, and as a result, an embroidered fabric with a beautiful appearance was obtained without fiber cutting by the embroidery needle.

[Example 2]

(1) A fiber was obtained by spinning and drawing under the same conditions as in Example 1, except that 50% of the carboxylic acid portion of glyoxylic acid was neutralized with sodium hydroxide. The performance evaluation results of the obtained fibers are shown in Table 1. In the obtained fiber, the reactivity of glyoxylic acid was 0.8 mol%. In addition, the fiber physical properties of the obtained fiber are: single filament fineness 2.1dtex, fiber crystallinity Xcf=43%, water dissolution temperature Wtb=15°C, fiber strength 7.6cN/dtex, fiber crystallinity Xcf and water dissolution temperature Wtb The relationship between satisfies the condition of formula (I), so the appearance of the fiber is good, without silk spots, etc., which is better than the conventional water-soluble PVA-based fiber.

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 3 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 42g/cm ² , the dissolution temperature in water SP=63°C, the degree of crystallinity Xcw=53%, the modulus of elasticity M=45N/50mm, the dissolution temperature SP of the nonwoven fabric and the nonwoven fabric The relationship between the crystallinity Xcw of the nonwoven fabric satisfies the condition of formula (II), and the relationship between the solution temperature SP of the nonwoven fabric in water and the elastic modulus M of the nonwoven fabric satisfies the condition of formula (III), and the solubility and mechanical properties are excellent.

(3) Further, the nonwoven fabric obtained in the above (2) was embroidered, and as a result, no fiber was cut by the embroidery needle, and an embroidered fabric with a beautiful appearance was obtained.

[Example 3]

(1) A fiber was obtained by spinning and drawing under the same conditions as in Example 1, except that PVA having a degree of saponification of 88 mol % was used. The performance evaluation results of the obtained fibers are shown in Table 1. The fiber appearance that obtains is good, does not have silk spots etc., and monofilament fineness is 2.1dtex, and fiber strength is 3.6cN/dtex, and the crystallinity Xcf=32% of fiber, dissolves temperature Wtb=5 ℃ in water, and the crystallinity Xcf of fiber and water The relationship of the dissolution temperature Wtb satisfies the condition of formula (I).

(2) Except having made the embossing temperature 140 degreeC, the fiber obtained by said (1) was heat embossed under the same conditions as Example 1, and the nonwoven fabric was obtained. Table 3 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 41g/cm ² , the dissolution temperature in water SP=21°C, the degree of crystallinity Xcw=32%, the modulus of elasticity M=34N/50mm, the dissolution temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relationship between the crystallinity Xcw of the nonwoven fabric satisfies the condition of formula (II), and the relationship between the solution temperature SP of the nonwoven fabric in water and the elastic modulus M of the nonwoven fabric satisfies the condition of formula (III), and the solubility and mechanical properties are excellent.

(3) Further, the nonwoven fabric obtained in the above (2) was embroidered, and as a result, no fiber was cut by the embroidery needle, and an embroidered fabric with a beautiful appearance was obtained.

[Example 4]

(1) Spinning and stretching were carried out under the same conditions as in Example 1 except that PVA having a degree of saponification of 98 mol % was used to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 1. The fiber appearance that obtains is good, does not have silk spots etc., and monofilament fineness is 2.2dtex, and fiber strength is 6.6cN/dtex, and the crystallinity Xcf=49% of fiber, dissolves temperature Wtb=62 ℃ in water, and the crystallinity Xcf of fiber and water The relationship of the dissolution temperature Wtb satisfies the condition of formula (I).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 3 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 40g/cm ² , the melting temperature SP=83°C, the degree of crystallinity Xcw=60%, the modulus of elasticity M=65N/50mm, the melting temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relationship between the degree of crystallinity Xcw satisfies the conditions of formula (II), and the relationship between the solution temperature SP in water of the nonwoven fabric and the elastic modulus M of the nonwoven fabric satisfies the conditions of formula (III), and the solubility and mechanical properties are excellent.

(3) Further, the nonwoven fabric obtained in the above (2) was embroidered, and as a result, no fiber was cut by the embroidery needle, and an embroidered fabric with a beautiful appearance was obtained.

[Example 5]

Except for using PVA with a viscosity average degree of polymerization of 1700 and a degree of saponification of 98.0 mol%, the stretching temperature is 20° C., and the stretching ratio is 10 times, spinning and stretching are carried out under the same conditions as in Example 2 to obtain fibers. In the obtained fiber, the reactivity of glyoxylic acid was 0.9 mol%. In addition, the obtained fiber has a good appearance without silk spots, and is superior to conventional water-soluble PVA-based fibers. In addition, the physical properties of the fiber are: single filament fineness is 2.0dtex, fiber strength is 8.5cN/dtex, fiber crystallinity Xcf=60%, water dissolution temperature Wtb=65°C, the relationship between fiber crystallinity Xcf and water dissolution temperature Wtb Satisfy the condition of formula (I).

[Example 6]

(1) PVA having a viscosity average degree of polymerization of 1700 and a degree of saponification of 96.0 mol% was poured into water to make the PVA concentration 16% by mass, and heated and dissolved at 90° C. under a nitrogen atmosphere. The obtained spinning stock solution was passed through a nozzle with a hole diameter of 0.16 mm and a number of holes of 108, and wet spinning was performed in a coagulation bath of a saturated aqueous solution of Glauber's salt.

(2) After further stretching the obtained fiber wet to 3 times in water, a sodium glyoxylate neutralization product obtained by neutralizing 50% of the carboxylic acid site as an ionic group with sodium hydroxide was added Pass through a 10 g/l water bath (extraction bath) to wash Glauber's salt, impregnate the inside of the fiber with a sodium glyoxylate neutralizer, and obtain a spinning yarn. Next, the obtained spun yarn was stretched in a hot air stretching furnace at 160° C. so that the total stretching ratio reached 6 times. The performance evaluation results of the obtained fibers are shown in Table 1.

(3) In the obtained fiber, the reactivity of glyoxylic acid was 1.0 mol%. In addition, the obtained fiber has a good appearance and no silk spots, etc., and is superior to conventional water-soluble PVA-based fibers. In addition, the fiber physical properties of the obtained fiber are: single filament fineness 2.2dtex, fiber strength 7.0cN/dtex, fiber crystallinity Xcf=45%, water dissolution temperature Wtb=18°C, fiber crystallinity Xcf and water dissolution temperature Wtb The relationship satisfies the condition of formula (I).

[Comparative example 1]

(1) Spinning and drawing were carried out under the same conditions as in Example 1 except that glyoxylic acid was not added to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2. The obtained fiber has a good appearance without silk spots, etc., but the monofilament fineness is 2.0dtex, the crystallinity Xcf of the fiber=35%, the dissolution temperature Wtb in water=30°C, and the relationship between the crystallinity Xcf of the fiber and the dissolution temperature Wtb in water is not satisfactory. The condition of formula (I), and satisfy the condition of formula (IV).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained non-woven fabric is 40g/cm ² , the dissolution temperature in water SP=75°C, the degree of crystallinity Xcw=42%, the modulus of elasticity M=35N/50mm, the dissolution temperature SP of the non-woven fabric and the non-woven fabric The relationship of the crystallinity Xcw of the non-woven fabric does not satisfy the condition of the formula (II), but satisfies the condition of the formula (V), and the relationship between the solution temperature SP in the water of the non-woven fabric and the elastic modulus M of the non-woven fabric does not satisfy the formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative example 2]

(1) Except that glyoxylic acid was not added and PVA having a degree of saponification of 88 mol % was used, spinning and stretching were carried out under the same conditions as in Example 1 to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2. The obtained fiber has a good appearance without silk spots, etc., but the monofilament fineness is 2.0dtex, the crystallinity Xcf of the fiber is 20%, the dissolution temperature Wtb in water is 5°C, and the relationship between the crystallinity Xcf of the fiber and the dissolution temperature Wtb in water is not satisfactory. The condition of formula (I), and satisfy the condition of formula (IV).

(2) Except that the embossing temperature was 140° C., the fibers obtained in the above (1) were subjected to a heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 40g/cm ² , the melting temperature SP=20°C, the degree of crystallinity Xcw=27%, the modulus of elasticity M=19N/50mm, the melting temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relation of crystallinity Xcw does not satisfy the condition of formula (II), but satisfies the condition of formula (V), and the relation of the solution temperature SP in the water of nonwoven fabric and the elastic modulus M of nonwoven fabric does not satisfy the condition of formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative example 3]

(1) Except that glyoxylic acid was not added, and PVA with a viscosity average degree of polymerization of 1700 and a saponification degree of 98 mol % was used, fibers were obtained by spinning and drawing under the same conditions as in Example 1. The performance evaluation results of the obtained fibers are shown in Table 2. The obtained fiber has a good appearance without silk spots, etc., but the monofilament fineness is 1.9dtex, the crystallinity Xcf of the fiber is 44%, the dissolution temperature Wtb in water is 65°C, and the relationship between the crystallinity Xcf of the fiber and the dissolution temperature Wtb in water is not satisfactory. The condition of formula (I), and satisfy the condition of formula (IV).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 39g/cm ² , the melting temperature SP=93°C, the degree of crystallinity Xcw=60%, the modulus of elasticity M=60N/50mm, the melting temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relation of crystallinity Xcw does not satisfy the condition of formula (II), but satisfies the condition of formula (V), and the relation of the solution temperature SP in the water of nonwoven fabric and the elastic modulus M of nonwoven fabric does not satisfy the condition of formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged due to the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative example 4]

(1) Spinning and drawing were carried out under the same conditions as in Example 1, except that the glyoxylic acid was not dissolved in the extraction bath, and the glyoxylic acid was attached to the fiber by roller touch (post-applying) after stretching. Stretch to get fibers. The performance evaluation results of the obtained fibers are shown in Table 2. The monofilament fineness of the obtained fiber was 2.5 dtex. In addition, the reactivity of glyoxylic acid is 1.1 mol%, and the dissolution temperature Wtb in water is 42°C, but glyoxylic acid only reacts with the fiber surface, so although the crystallinity Xcf of the fiber is 32%, the fiber strength is as low as 5.5cN/ dtex. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained non-woven fabric is 40g/cm ² , the melting temperature SP=63°C, the degree of crystallinity Xcw=40%, the modulus of elasticity M=40N/50mm, the melting temperature SP of the non-woven fabric is the same as that of the non-woven fabric The relation of crystallinity Xcw does not satisfy the condition of formula (II), but satisfies the condition of formula (V), and the relation of the solution temperature SP in the water of nonwoven fabric and the elastic modulus M of nonwoven fabric does not satisfy the condition of formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative Example 5]

(1) Spinning and stretching were carried out under the same conditions as in Example 1 except that glyoxylic acid was added to the stock solution instead of the extraction bath to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2. The obtained fiber has a good appearance, no silk spots, etc., the single filament fineness is 2.3dtex, and the dissolution temperature Wtb in water is 34°C, but the reaction of glyoxylic acid is too high, which is 9.9 mol%, so the crystallinity Xcf of the fiber is as low as 25 %, so the fiber strength is as low as 5.0cN/dtex. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 41g/cm ² , the melting temperature SP=73°C, the degree of crystallinity Xcw=28%, the modulus of elasticity M=31N/50mm, the melting temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relation of crystallinity Xcw does not satisfy the condition of formula (II), but satisfies the condition of formula (V), and the relation of the solution temperature SP in the water of nonwoven fabric and the elastic modulus M of nonwoven fabric does not satisfy the condition of formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative Example 6]

(1) Except for changing the aldehyde to benzaldehyde, spinning and drawing were carried out under the same conditions as in Example 1 to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2. The obtained fiber had a good appearance without silk spots and the like, and the fineness per filament was 2.0 dtex. In addition, the reactivity of benzaldehyde was 1.0 mol%, the dissolution temperature Wtb in water was 55°C, and the fiber strength was as low as 4.9 cN/dtex although the degree of crystallinity Xcf was 34%. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(2) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained non-woven fabric is 40g/cm ² , the dissolution temperature SP=70°C, the crystallinity Xcw=38%, the modulus of elasticity M=35N/50mm, the dissolution temperature SP of the non-woven fabric is the same as that of the non-woven fabric The relation of crystallinity Xcw does not satisfy the condition of formula (II), but satisfies the condition of formula (V), and the relation of the solution temperature SP in the water of nonwoven fabric and the elastic modulus M of nonwoven fabric does not satisfy the condition of formula (III) condition, and satisfy the condition of formula (VI).

(3) A further attempt was made to embroider the nonwoven fabric obtained in the above (2), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative Example 7]

(1) In addition to not adding glyoxylic acid, the PVA with a viscosity average degree of polymerization of 1200 and a degree of saponification of 96.0 mol% is dissolved in water to make the PVA concentration reach 33% by mass. Dry spinning was carried out per minute, followed by stretching to 5 times at 135°C to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2.

(2) The obtained fiber has a good appearance, no silk spots, etc., the single filament fineness is 4.0dtex, the dissolution temperature Wtb in water is 45°C, and although the crystallinity Xcf is 30%, the fiber strength is as low as 4.8cN/dtex. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(3) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 39g/cm ² , the dissolution temperature in water SP=55°C, the degree of crystallinity Xcw=35%, the modulus of elasticity M=30N/50mm, the dissolution temperature SP of the nonwoven fabric and the nonwoven fabric The relationship of the crystallinity Xcw of the non-woven fabric does not satisfy the condition of the formula (II), but satisfies the condition of the formula (V), and the relationship between the solution temperature SP in the water of the non-woven fabric and the elastic modulus M of the non-woven fabric does not satisfy the formula (III) condition, and satisfy the condition of formula (VI).

(4) A further attempt was made to embroider the nonwoven fabric obtained in the above (3), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative Example 8]

(1) Without adding glyoxylic acid, dissolve PVA with a viscosity average degree of polymerization of 400 and a saponification degree of 99.9 mol% in water to make the PVA concentration 39.7% by mass, and add 0.3 parts by mass of sodium borate therein to prepare a spinning dope. This stock solution was dry-spun at 500 m/min with a nozzle having a hole diameter of 0.1 mm and a number of holes of 50, followed by stretching to 4 times at 130° C. to obtain fibers. The performance evaluation results of the obtained fibers are shown in Table 2.

(2) The obtained fiber has a good appearance, no silk spots, etc., the single filament fineness is 5.0dtex, and the dissolution temperature Wtb in water is 70°C, but because the degree of polymerization of PVA is low, although the crystallinity Xcf is 35%, the fiber strength is low Up to 2.7cN/dtex. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(3) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained nonwoven fabric is 41g/cm ² , the dissolution temperature in water SP=72°C, the degree of crystallinity Xcw=40%, the modulus of elasticity M=20N/50mm, the dissolution temperature SP of the nonwoven fabric is the same as that of the nonwoven fabric The relationship of the crystallinity Xcw of the non-woven fabric does not satisfy the condition of the formula (II), but satisfies the condition of the formula (V), and the relationship between the solution temperature SP in the water of the non-woven fabric and the elastic modulus M of the non-woven fabric does not satisfy the formula (III) condition, and satisfy the condition of formula (VI).

(4) A further attempt was made to embroider the nonwoven fabric obtained in the above (3), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

[Comparative Example 9]

(1) Without adding glyoxylic acid, PVA with a viscosity average degree of polymerization of 1700 and a degree of saponification of 98.5 mol% is dissolved in water so that the PVA concentration reaches 16.0% by mass, and the spinning dope obtained in this way passes through a pore diameter of 0.16mm and a number of pores of 108 Wet spinning in a coagulation bath with a liquid temperature of 40°C composed of saturated Glauber's salt aqueous solution. The fiber thus obtained was stretched three times wet in water, dried at 120°C, and then heat-treated at 215°C to obtain a fiber. The performance evaluation results of the obtained fibers are shown in Table 2.

(2) The appearance of the obtained fiber is good, without silk spots, etc., the single filament fineness is 10.0dtex, and the dissolution temperature Wtb in water is 80°C, but the stretching condition of the fiber is only wet stretching, so although the crystallinity Xcf is 40% , but the fiber strength is as low as 4.7cN/dtex. In addition, the relationship between the degree of crystallinity Xcf of the obtained fiber and the dissolution temperature Wtb in water does not satisfy the condition of formula (I), but satisfies the condition of formula (IV).

(3) The fibers obtained in the above (1) were subjected to heat embossing treatment under the same conditions as in Example 1 to obtain a nonwoven fabric. Table 4 shows the evaluation results of the obtained nonwoven fabric. The weight per unit area of the obtained non-woven fabric is 40g/cm ² , the dissolution temperature in water SP=85°C, the degree of crystallinity Xcw=45%, the modulus of elasticity M=30N/50mm, the dissolution temperature SP of the non-woven fabric is the same as that of the non-woven fabric The relationship of the crystallinity Xcw of the non-woven fabric does not satisfy the condition of the formula (II), but satisfies the condition of the formula (V), and the relationship between the solution temperature SP in the water of the non-woven fabric and the elastic modulus M of the non-woven fabric does not satisfy the formula (III) condition, and satisfy the condition of formula (VI).

(4) A further attempt was made to embroider the nonwoven fabric obtained in the above (3), but it was found that the nonwoven fabric was damaged by the embroidery needle, or the surface of the fibers constituting the nonwoven fabric was damaged, etc., and an embroidered fabric with a beautiful appearance was not obtained. .

It is clear from the results in Table 1 and FIG. 1 that the water-soluble PVA-based fiber of the present invention has excellent water solubility and excellent fiber strength. Also, water solubility can be easily controlled by the degree of neutralization of ionic groups. On the other hand, it is clear from the results in Table 2 that the prior art or the use of a compound having an ionic group that does not satisfy the constituent requirements of the present invention, or the reactivity of the compound having an ionic group does not satisfy the requirements of the present invention In this case, compared with the fiber of the present invention, although the degree of crystallinity is low, the dissolution temperature in water tends to be high, and the fiber strength of the obtained fiber is low.

From the results of Table 3 and Fig. 2 and Fig. 3, it can be clearly seen that the water-soluble nonwoven fabric of the present invention has excellent water solubility and excellent mechanical properties, so when the nonwoven fabric of the present invention is embroidered, it can be obtained Good-looking non-woven fabric. On the other hand, it is clear from the results in Table 4 that the prior art or non-woven fabrics made of fibers that do not satisfy the constituent requirements of the present invention, compared with the non-woven fabrics of the present invention, have low crystallinity, but have The melting temperature tends to be high, and the mechanical properties of the obtained nonwoven fabric are also low. Therefore, when the nonwoven fabric is embroidered, a nonwoven fabric with a beautiful appearance cannot be obtained.

According to the present invention, it is possible to provide water-soluble PVA-based fibers having both water-soluble properties and mechanical properties including tensile strength, which cannot be realized in the conventional art. In addition, the water-soluble PVA-based fiber of the present invention does not require special steps, and can be produced inexpensively by ordinary spinning and drawing steps. Furthermore, the water-soluble PVA-based fiber of the present invention can appropriately control water solubility. In addition, by using the water-soluble PVA-based fibers of the present invention, it is possible to provide a water-soluble nonwoven fabric having both water-soluble properties and mechanical properties including elastic modulus, which cannot be realized in the prior art, and is expected to be extremely effective for use in Burnt-out lace has many uses headed with a base fabric.

Claims (4)

1. A water-soluble polyvinyl alcohol fiber is characterized in that, in any operation of drying, stretching and heat treatment, the fiber reacts with 0.01-5 mol% glyoxylic acid or its metal neutralization, The relationship between the degree of crystallinity Xcf in percentage and the dissolution temperature Wtb in Celsius of this water-soluble polyvinyl alcohol fiber satisfies the following formula (I), Wtb＜2.50Xcf-70···(I) Among them, 30%≤Xcf≤80%. 2. the manufacture method of the described water-soluble polyvinyl alcohol fiber of claim 1, the polyvinyl alcohol polymer with degree of polymerization 1000-4000 and degree of saponification 88 mol% is dissolved in organic solvent, the spinning stock solution obtained is in Wet or dry-wet spinning is carried out in a solidification bath mainly composed of an organic solvent capable of curing the polymer, and then passed through an extraction bath in which 1-50 g/l of glyoxylic acid or its metal neutralization is dissolved , impregnating the fiber with glyoxylic acid or its metal neutralized product, reacting and introducing it in any of the steps of drying, stretching, and heat treatment, and at the same time, the total draw ratio of all steps is 3 times or more. 3. A water-soluble non-woven fabric, characterized in that, is a non-woven fabric comprising the water-soluble polyvinyl alcohol fiber according to claim 1, the crystallinity Xcw of the non-woven fabric in percentage and the water temperature in Celsius The relationship of the dissolution temperature SP satisfies the following formula (II), SP＜2.50Xcw-50···(II) Among them, 30%≤Xcw≤65%. 4. water-soluble non-woven fabric according to claim 3, is characterized in that, the elastic modulus M of non-woven fabric in N/50mm and the relation of dissolution temperature SP in the water of Celsius thermometer satisfy following formula (III ), SP＜1.60M-22 ···(III) Among them, 30N/50mm≤M≤80N/50mm.

Images