JPH06287852A - Production of netlike fiber nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain a nonwoven fabric, having high strength and bacterial barrier properties and further hygroscopicity and printability by carrying out the flash spinning of a spinning solution composed of a polyethylenic polymer, a polyvinyl alcoholic polymer, a solvent and water, subsequently forming a web and then partially heat bonding the resultant web. CONSTITUTION:A high-density polyethylene (A), a polyvinyl alcoholic polymer (B), a solvent (C) and water (D) are dissolved and mixed at a high temperature under a high pressure so as to satisfy 1<=BX100/[A+B]<=25, 5<=(A+B)<=25, 40<=C<=74 and 5<=BX100/[B+D]<=20 (A, B, C and D are respectively wt.%) to prepare a spinning solution, which is then passed through a spinning hole having a pressure dropping chamber under an autogenous pressure or a higher pressure and spun into the atmosphere. The solvent is simultaneously instantaneously vaporized to form netlike fiber, which is further formed into a web. The resultant web is then passed through embossing rolls under conditions in which the roll temperature (T deg.C) and the linear pressure (P kg/cm<2>) satisfy [melting point of the polymer-40]<=T<=[melting point of the polymer] and 0.5<=P<=5C to afford the partially heat bonded netlike fiber nonwoven fabric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a reticulated fiber composed of a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B, has high strength, is highly flexible, has a bacterial barrier property, and has a moisture absorption property. The present invention relates to a method for producing a reticulated fiber non-woven fabric which has excellent heat resistance and printability and is suitable as a material for heat insulating materials, protective clothing in the medical and hygiene field, interior products such as carpets, and various life-related materials.

[0002]

2. Description of the Related Art Conventionally, a method for producing an ultrafine reticulated fiber nonwoven fabric by the flash spinning method has been known. The flash spinning method is a method in which a solution obtained by dissolving a thermoplastic polymer in a specific solvent under high temperature and high pressure is further pressurized to a pressure higher than the autogenous pressure and spun into the atmosphere. Japanese Patent No. 3081519 discloses a technique for obtaining the reticulated fiber by this flash spinning method. However, the non-woven fabric made by using the reticulated fiber is limited in its use as a non-woven fabric product because the constituent fibers themselves are made of a thermoplastic polymer having a hydrophobic property or at least a poor hygroscopic property. For example, when a hydrophobic or at least poorly hygroscopic thermoplastic polymer such as polyethylene or polypropylene is used, the resulting reticulated fiber nonwoven fabric has excellent water repellency and water resistance, but naturally has poor hygroscopicity. Therefore, there is a problem that it cannot be applied to fields of application such as synthetic paper, which requires hygroscopicity and printability, for example, because printing or writing is performed using water-based ink.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and is composed of a reticulated fiber composed of a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B, and has high strength, high flexibility, and bacteria. Efficiently manufacture reticulated non-woven fabrics that have barrier properties and excellent hygroscopicity and printability, and are suitable as materials for heat insulation materials, protective clothing in the medical and hygiene field, interior goods such as carpets, and various life-related materials. It is intended to provide a way to do.

[0004]

The present inventors have arrived at the present invention as a result of extensive studies to solve the above problems. That is, according to the present invention, a solution prepared by dissolving and mixing a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B in the same bath with a solvent and water under high temperature and high pressure is used as a spinning solution, which is prepared under autogenous pressure. Alternatively, it is spun into the atmosphere through a spinning hole having a pressure drop chamber under pressure, and immediately after spinning, the solvent is instantaneously vaporized to form a reticulated fiber, and then a web is formed from the reticulated fiber. The gist of the present invention is a method for producing a reticulated fiber nonwoven fabric, which is characterized in that a thermal thermocompression treatment is performed.

Next, the manufacturing method of the present invention will be described in detail. Polyethylene polymer A used in the production method of the present invention
The term “fiber-forming low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, or copolymerized polyethylene in which ethylene is the main component and other components are copolymerized, and It has a melting point of 100 ° C. or higher. If the melting point of these polymers is less than 100 ° C., they will be melted even by boiling water, and the practicability of the polymers will be reduced when they are used as a nonwoven fabric using reticulated fibers. The polyethylene polymer A has a melt index of 0.3 g / 1 measured by the method described in ASTM-D-1238 (E).
It is preferable to use one having a high viscosity of 0 minutes or more and 30 g / 10 minutes or less. This melt index is 0.3 g / 1
If it is less than 0 minutes, the solution viscosity of the solution obtained by dissolving the polymer in the solvent and water becomes extremely high, and it becomes difficult to obtain ultrafine fibrils, which is not preferable. On the other hand, when the melt index exceeds 30 g / 10 min, the degree of polymerization is low and the fibril strength, that is, the strength of the nonwoven fabric is not improved. Further, when the melt index is high and the degree of polymerization is too low, the flash spinning It is not preferable because it cannot follow the spinning speed and the spun fibers have a short fiber shape or a substantially powdery shape. In the present invention, the polyethylene-based polymer A or a spinning solution prepared by dissolving the polyethylene-based polymer A in a solvent contains a matting agent, a light-resistant agent, a heat-resistant agent, a pigment, a fiber-spreading agent, which are commonly used for fibers. Agents, ultraviolet absorbers, heat storage agents, stabilizers and the like can be added as long as the effects of the present invention are not impaired.

The polyvinyl alcohol-based polymer B used in the production method of the present invention is a fiber-forming polyvinyl alcohol or other vinyl groups such as ethylene, itaconic acid and vinylpyrrolidone which are 10 mol% or less, preferably 2 mol. % Copolymerized polyvinyl alcohol and the like. The degree of polymerization of the polymer B is not particularly limited, but when it is desired to improve the strength of the non-woven fabric obtained by using the reticulated fibers, the average polymerization of the aqueous solution of the polymer measured at a temperature of 30 ° C. by a viscosity method. The degree is 1000 or more, preferably 1500 or more, and particularly preferably 1700 or more. Further, the saponification degree of the polymer B is not particularly limited, but when it is desired to improve the heat resistance of the nonwoven fabric, the saponification degree of the polymer is 87 mol% or more, preferably 9 mol% or more.
It is preferably 0 mol% or more, particularly preferably 95 mol% or more.

In the manufacturing method of the present invention, first, reticulated fibers are formed by the so-called flash spinning method. That is,
A solution prepared by dissolving and mixing the polyethylene polymer A and the polyvinyl alcohol polymer B in the same bath with the solvent C and water D under high temperature and high pressure was used as a spinning solution, which was added under autogenous pressure or under autogenous pressure. Under the pressure, it is spun into the atmosphere through a spinning hole having a pressure drop chamber, and immediately after spinning, the solvent is instantaneously vaporized to form a reticulated fiber. When a solution is prepared, solvent C and water D are used which are non-solvents for the polymers A and B at room temperature but are good solvents at high temperature. Examples of the solvent C include aromatic hydrocarbons such as benzene and toluene, butane, pentane,
Hexane, heptane, octane or aliphatic hydrocarbons such as isomers or homologs thereof, alicyclic hydrocarbons such as cyclohexane, methylene chloride, carbon tetrachloride, chloroform,
1,1-dichloro-2,2 difluoroethane, 1,2-
Halogenated hydrocarbons such as dichloro-1,1 difluoroethane, methyl chloride, ethyl chloride and fluorocarbon, alcohols, esters, ethers, ketones, nitriles, amides, sulfur dioxide, carbon disulfide, unsaturated hydrocarbons such as nitromethane, or the above Mixtures of the solvents mentioned can be used. In recent years, attention has been paid to the protection of the global environment,
From this point of view, it is particularly preferable to avoid a solvent that destroys the ozone layer, and therefore methylene chloride as the solvent C,
1,1-dichloro-2,2 difluoroethane, 1,2-
The use of dichloro-1,1 difluoroethane is preferable because it does not harm the global environment as seen when conventional freon is used as a solvent. When the nonwoven fabric of the present invention is produced, water D is used together with the solvent C. The water D is the polyvinyl alcohol polymer B.
And has a function as a dispersant in the spinning solution. As the water D, so-called pure water is preferably used.

In the production method of the present invention, it is preferable that the polyethylene polymer A and the polyvinyl alcohol polymer B in the solution satisfy the formula (1). If the abundance ratio [B × 100 / (A + B)] of the polyvinyl alcohol-based polymer B in this solution is less than 1, the hygroscopicity and printability of the reticulated fibers themselves are reduced, which is not preferable. On the other hand, when the abundance ratio exceeds 25, the tackiness and adhesiveness of the fibers are increased, and the spun fibers are obtained because the fibrils are bonded to each other at their side faces and the fibers are not well opened. The texture of the non-woven fabric is significantly reduced, especially 10
In the case of a low basis weight of 0 g / m ² or less, the quality is significantly lowered, which is not preferable. Therefore, in the present invention, the abundance ratio is set to 1 to 25, preferably 2 to 20, and particularly preferably 3 to 10.

In the production method of the present invention, considering the spinnability during flash spinning and the characteristics of the obtained reticulated fiber, the polyethylene polymer A, the polyvinyl alcohol polymer B and the solvent C are used as the spinning solution. It is preferable to use a solution in which the water and the water D satisfy the above formulas (2) to (4), respectively. In this spinning solution, when the concentration of the polymer [A + B] in the spinning solution is less than 5% by weight, the area occupied by the polymer in the system is small when the polymer and the solvent are phase-separated immediately after flash spinning. Moreover, the spun fibers do not form a continuous structure because they are scattered, and the strength is not improved, which is not preferable. On the other hand, polymer [A + B]
When the concentration of the polymer exceeds 25% by weight, the concentration of the polymer [A + B] becomes too high and the dissolution becomes non-uniform, so that it is not possible to obtain ultrafine fibrils, and the spun fiber is This results in the formation of a hollow structure having side surfaces bonded to each other and having a cavity inside, and the strength is not improved due to the structure, which is not preferable. Further, if the concentration of the solvent in the spinning solution is less than 40% by weight, the solution viscosity of the solution obtained by dissolving the polymer is too high and the dissolution becomes nonuniform, so that it is not possible to obtain ultrafine fibrils. Moreover, the spun fibers form a hollow structure. On the other hand, when the concentration of the solvent exceeds 74% by weight, a continuous structure of fibrils does not form, which is not preferable. Further, the fraction (%) of the polymer B in [B (wt%) + D (wt%)] is 5
If it is less than%, the content of the polymer B in the spun fiber becomes small and the hygroscopicity of the fiber itself becomes insufficient. On the other hand, the weight of [B (wt%) + D (wt%)] If the fraction (%) of the polymer B exceeds 20%, the polymer B gels and the viscosity becomes too high, making spinning difficult, which is not preferable.

According to the production method of the present invention, when a spinning solution is prepared, all the polymers [A + B] are used as solutes, and these solutions are charged together with the solvent C and water D in a dissolution apparatus and the solution is heated and kneaded. The prepared solution is used as a spinning solution. As the melting device, an autoclave which has been used most widely in the past, or a continuous melting device including, for example, an extruder and a kneading device arranged continuously with the extruder can be used. When the temperature of the spinning solution is increased and kneaded in the dissolving device, the spinning pressure is further increased by pressurizing with an inert gas such as nitrogen or carbon dioxide having a purity of 99% by weight or more and not containing oxygen. It is possible and preferable. The gas of nitrogen or carbon dioxide is a so-called inert gas, which hardly dissolves in the spinning solution and does not adversely affect the polymer, so that a substantial pressure can be applied to the spinning solution. Further, if the inert gas is injected before the temperature of the spinning solution in the dissolution apparatus is raised, it is possible to prevent the deterioration of the polymer, promote the solubility of the polymer, and make the fibrils extremely fine.

The dissolution time and the dissolution temperature for dissolving all the polymers [A + B] in the solvent C and water D in the dissolution apparatus depend on the viscosity of the polymer, that is, the degree of polymerization, and it is difficult to unconditionally specify. Is. In short, all polymers [A + B]
Is particularly limited as long as it is sufficiently dissolved in the solvent and the spinning solution is flash-spun to obtain fibers having a structure in which ultrafine fibrils are aggregated and three-dimensionally reticulately spread. Although it is not a thing, if it is intentionally specified, the time is 45 minutes or more and 90 minutes or less, and the temperature is 16 minutes.
The temperature is preferably 0 ° C. or higher and 200 ° C. or lower. This melting takes longer for low temperature melting and shorter for high temperature melting. When the time for dissolution is less than 45 minutes and the temperature is less than 160 ° C, all the polymers [A +
B] becomes insufficiently dissolved, and it becomes difficult to obtain fibers composed of uniform fibrils. On the other hand, when the time exceeds 90 minutes and the temperature exceeds 200 ° C., the polymer B in the spinning solution is
However, the strength of the fiber is not improved due to the coloring and thermal decomposition of the fiber, and even if the strength is maintained, the fiber is colored, which is not preferable.

The pressure for flash-spinning the prepared spinning solution depends on the concentration of the total polymer [A + B], the amount of solvent, the amount of water, the amount of inert gas injected, etc., but is not generally specified. 40 kg / cm ² or more 16
It is preferably 0 kg / cm ² or less. The strength of the fiber is expressed by sufficiently stretching and orienting the molecular chains of the polymer. Therefore, the flash spinning method, that is, the spinning solution is spun through a spinning hole having a pressure drop chamber, and immediately after spinning, the solvent is used. In the method of instantaneously evaporating the solvent to form a reticulated fiber structure, this stretching and orientation is performed by the explosive force that accompanies the instantaneous evaporation of the solvent immediately after spinning. The explosive force is the vaporizing force when the solvent is instantly vaporized, and usually means the force when the solvent vaporizes at once in 0.1 second or less. Therefore, this spinning pressure is 40 kg /
cm ² or more is preferable, and the spinning pressure is 40 kg /
If it is less than cm ² , the explosive force at the time of flash spinning using a spinning solution is reduced, the orientation of the fibrils is insufficient, the strength is not improved, and the spinning state becomes non-uniform. It becomes difficult to stably obtain highly fibrillated reticulated fibers. On the other hand, this spinning pressure is 160
It is preferable that the pressure is not more than kg / cm ² and the spinning pressure is 16
When it exceeds 0 kg / cm ² , the viscosity of the polymer in the spinning solution is lowered and the strength of the fibril is not improved, which is not preferable.

In the manufacturing method of the present invention, next, the spun reticulated fiber group is made to collide with an opening plate which is inclined by about 45 ° at a position about 25 mm away from the tip of the spinning hole,
A web is prepared by continuously depositing it on a moving and depositing means such as a screen conveyor, and then a partial thermocompression treatment is performed by applying heat and pressure to this web to partially heat the reticulated fibers partially. Join. When the web is subjected to the partial thermocompression bonding treatment, for example, an embossing method in which a web is passed between a heated embossing roll having protrusions on the surface and a heated metal roll having a smooth surface, Alternatively, a method using an ultrasonic fusing device can be adopted, but the former method is preferable in terms of productivity. The shape of the protrusions of the embossing roll, that is, the shape of the crimping point is not particularly limited, and examples thereof include a round shape, an elliptical shape, a rhombus shape, a triangular shape, a T shape, a − shape,
Any form such as a well type or a lattice type may be used.
When the hot embossing roll is used to partially thermocompress the web, the roll temperature T (° C.) and the linear pressure P are applied.
It is preferable to carry out under the conditions that (kg / cm) and the above formulas (5) and (6) are satisfied. The melting point (° C.) of the polymer in the above formula (5) is the melting point of the polymer having the lowest melting point among the polymers constituting the fiber. The term "melting point of the polymer" as used herein means a temperature which gives an extreme value of a melting absorption heat curve measured by using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elma Co. at a temperature rising rate of 20 ° C / min. To do.
The roll temperature T (° C) is [melting point of polymer -40].
If it is less than 1, the strength of the non-woven fabric is not improved because the space between the reticulated fibers is not sufficiently thermocompressed. On the other hand, if the roll temperature T (° C) exceeds the [melting point of the polymer], the reticulated fibers are widely fused. The meaning of obtaining ultrafine fibril fibers disappears, the polymer is thermally deteriorated to color the nonwoven fabric, or it becomes difficult to melt the fibers and bond them to the roller to make them into a nonwoven fabric, which is not preferable. . Also, the linear pressure P (kg / c
When m) is less than 0.5, the strength of the non-woven fabric is not improved because the interwoven fibers are not sufficiently thermocompression bonded, while the linear pressure P
When (kg / cm) exceeds 50, the non-woven fabric is melted into a film beyond the hot pressing contact region of the embossing roll, which is not preferable. Further, it is preferable that the total ratio of the pressure contact area per unit area, that is, the pressure contact area ratio is usually 4% or more and 40% or less in percentage. When the pressure contact area ratio is less than 4%, not only the strength of the obtained non-woven fabric is lowered but also the rigidity is low, while the pressure contact area ratio is 40%.
%, The rigidity of the obtained nonwoven fabric becomes too high, which is not preferable.

The non-woven fabric obtained by the production method of the present invention is obtained by finely dispersing the polyvinyl alcohol polymer B in the polyethylene polymer A.
-10 μm equivalent diameter and specific surface area of at least 10 m ²
/ G of fibrils are continuously aggregated, and are composed of reticulated fibers having a three-dimensional reticulated structure and spread in a reticulated structure, and the reticulated fibers are heat-bonded throughout. The term “finely dispersed” as used herein means that the polyvinyl alcohol-based polymer B
Mean that they are randomly dispersed in the fibers in the form of fine particles or fibrils having a diameter of about 0.0001 to 0.1 μm. This polyvinyl alcohol polymer B
As for the scattered state of, for example, the fiber is electron-stained with osmium tetroxide, then embedded with epoxy resin, trimmed and surfaced, stained with ruthenium tetroxide in the embedding block, and then stained and fixed. It can be known by cutting out the fiber into an ultrathin section and observing it with a transmission electron microscope at a magnification of about 60,000 times. The specific surface area (m ² / g) of the reticulated fiber as used herein is measured by the BET nitrogen adsorption method, and the monomolecular volume of nitrogen per 1 g of sample fiber, that is, the entire surface of the sample fiber is a monolayer. The amount of adsorbed nitrogen when coated with. This non-woven fabric is
Since the polyvinyl alcohol-based polymer B is composed of the reticulated fibers randomly dispersed in the extremely fine particle state or fibril state in the polyethylene-based polymer A as described above, the moisture absorption is almost permanent. It will be equipped with nature. Moreover, in this non-woven fabric, the specific surface area of the reticulated fibers is at least 10 m ² / g and the surface area of the fibers is large, that is, the reticulated fibers are sufficiently reticulated and the texture of the non-woven fabric is improved. In addition, since the reticulated fibers are partially thermocompressed, the strength is high,
Moreover, it is highly flexible, for example, more flexible and more durable than conventional pulp-based paper.

[0015]

EXAMPLES Next, the present invention will be specifically described based on Examples. The measurement and evaluation of various characteristics in the examples were carried out by the following methods. Melting point of polymer: Differential scanning calorimeter D manufactured by Perkin Elmer
The melting point was defined as the temperature at which the exothermic value of the melting and absorption heat curve measured using the SC-2 type at a temperature rising rate of 20 ° C./min. Melt index (g / 10 minutes): ASTM D 1
It was measured by the method described in 238 (E). Nonwoven fabric thickness (mm): sample length 10 cm, sample width 1
5 samples of 0 cm were prepared, and a load of 4.5 g / cm ² was applied to each sample using a thickness measuring instrument manufactured by Daiei Kagaku Seiki Seisakusho. After standing for 10 seconds, the thickness was measured. The average value of the obtained values was used as the thickness (mm) of the nonwoven fabric. Nonwoven fabric KGSM tensile strength (kg / 5cm): JIS
According to the strip method described in L-1090, 10 points with a sample length of 10 cm and a sample width of 5 cm were measured at a tensile speed of 10 cm / min, and the average value of the obtained tensile strength was measured per 100 g / m ² of basis weight. Converted, non-woven KGS
M tensile strength (kg / 5 cm). Tear strength (kg) of non-woven fabric: Measured according to the method described in JIS K-7331. Tensile elongation (%) of the non-woven fabric: According to the strip method described in JIS L-1090, ten samples were measured at a tensile speed of 10 cm / min, and the average value of the obtained tensile elongations was measured. (%). Specific surface area of non-woven fabric fibers (m ² / g): BE using a nitrogen adsorption device BELSORP28 manufactured by Nippon Bell Co., Ltd.
Specific surface area (m ²
/ G) was determined. Moisture absorption rate (%) of non-woven fabric: 5 samples were prepared, and this sample was dried using a hot air dryer at a treatment temperature of 80 ° C and a treatment time of 24 hours, cooled in a desiccator, and then dried completely. The weight W ₁ (g) was measured. Then, this sample was allowed to stand in a thermo-hygrostat at a temperature of 20 ° C. and a humidity of 65%, and the weight W ₂ when the change in mass with time reached a saturation value
(G) was measured, and the moisture absorption rate (%) of the nonwoven fabric was determined from the obtained weight value by the following formula (7). Moisture absorption nonwoven (%) = [(W ₂ / W ₁₎ -1] × 100 (7)

Examples 1 to 4 and Comparative Example 1 Melting point is 132 ° C. and melt index is 0.8 g /
The autoclave was filled and closed with 10 minutes of a high-density polyethylene polymer A, a 10 wt% aqueous solution of a polyvinyl alcohol polymer B having an average degree of polymerization of 1700 and a degree of saponification of 98.5 mol%, and dry ice. Then, methylene chloride C and pure water D were injected into the autoclave, and this solution was heated at an appropriate speed for 60 minutes while stirring. This solution had a total polymer [A + B] concentration of 15% by weight, a polyethylene polymer A / polyvinyl alcohol polymer B weight ratio (A / B) was mixed as shown in Table 1, and methylene chloride C was added. The concentration is 63% by weight, and the concentration of pure water D is 22% by weight. Subsequently, after the internal pressure at 170 ° C. internal temperature of the autoclave reaches 100 kg / cm ² G, pore size has a pressure drop chamber internal pressure that is immediately opened autoclave valve at a spinning pressure of 100kg / cm ² G 0.7
The spinning solution was discharged into the atmosphere through a spinning hole having a hole length / pore diameter ratio of 5 and a ratio of pore length / pore diameter of 1 to spun out a reticulated fiber composed of the polyethylene polymer A and the polyvinyl alcohol polymer B, and spun a spun fiber group. A web was prepared by colliding with a fiber-spreading plate arranged at an angle of 45 ° at a position 25 mm away from the exit hole and continuously accumulating on a movable screen conveyor. Then,
The obtained web is subjected to a partial thermocompression bonding treatment under the conditions of a surface temperature of 125 ° C. and a linear pressure of 25 kg / cm, using a hot embossing roll having a pressing area ratio of 17% and a metal roll having a heated and smooth surface. Then, a reticulated fiber nonwoven fabric having a basis weight of about 50 g / m ² was obtained. Table 1 shows the polymer conditions and the properties of the obtained reticulated fiber nonwoven fabric. In Table 1, PE is a polyethylene polymer, PVA is a polyvinyl alcohol polymer, MIX is a melt index, MD is the longitudinal direction, and C is
D indicates the lateral direction.

[0017]

[Table 1]

In Examples 1 to 3, as is apparent from Table 1, nonwoven fabrics having practical strength and high specific surface area of fibers, excellent hygroscopicity and no coloring at all could be obtained. . In addition, this non-woven fabric is electron-dyed with osmium tetroxide, then embedded in epoxy resin, trimmed and surfaced, dyed with ruthenium tetroxide in the embedding block, and the non-woven fabric after dyeing and fixing is ultra-thin. Cut into sections,
The surface of the constituent fibers was photographed with an electron microscope at a magnification of about 60,000 using a transmission electron microscope, and the surface morphology was observed.
The fine particles of the polyvinyl alcohol polymer of m had a structure in which they were randomly dispersed in the polyethylene polymer. In addition, in Example 4, although a nonwoven fabric having practical strength, high fiber specific surface area, and excellent hygroscopicity could be obtained, this nonwoven fabric was spun with a high abundance ratio of polyvinyl alcohol polymer. The fibers had low texture because the fibrils joined to each other on their sides and did not open uniformly. On the other hand, Comparative Example 1
Then, as is clear from Table 1, although a nonwoven fabric having a high specific surface area was obtained because it has practical strength and the fibril formation is good, this nonwoven fabric is formed from polyethylene polymer alone. It had no hygroscopicity.

Examples 5 to 13 Part of the web obtained in Example 2 was changed in the same manner as in Example 2 except that the temperature, the linear pressure and the pressure contact area ratio of the hot embossing roll were changed as shown in Table 2. Subjected to dynamic thermocompression treatment,
A reticulated fiber nonwoven fabric having a basis weight of about 50 g / m ² was obtained. Table 2 shows the heat-bonding treatment conditions and the properties of the obtained reticulated fiber nonwoven fabric. In Table 2, MD indicates the vertical direction and CD indicates the horizontal direction.

[0020]

[Table 2]

In Examples 5 to 8 and 13, as is apparent from Table 2, nonwoven fabrics having practical strength, excellent hygroscopicity and no coloring at all could be obtained. Further, in Example 9, since the temperature (° C.) of the hot embossing roll was less than [melting point of polyethylene polymer −40], although the strength was slightly low, a nonwoven fabric excellent in hygroscopicity could be obtained. Further, in Example 10, although the temperature (° C.) of the hot embossing roll was slightly above the [melting point of the polyethylene polymer], the surface was slightly melted to form a film,
In Example 11, although the surface of the hot embossing roll was slightly melted to form a film due to the high linear pressure of the hot embossing roll, a nonwoven fabric having excellent strength and hygroscopicity could be obtained. Furthermore, in Example 12, although a slight fluff was observed on the surface because the press contact area ratio of the hot embossing roll was slightly low, a nonwoven fabric having excellent strength and hygroscopicity could be obtained.

[0022]

The method for producing a reticulated fiber nonwoven fabric according to the present invention comprises:
A solution prepared by dissolving and mixing the polyethylene-based polymer A and the polyvinyl alcohol-based polymer B in the same bath at a high temperature and a high pressure using a solvent and water is used as a spinning solution, and the solution is reduced under autogenous pressure or under pressure. After spinning into the atmosphere through a spinning hole with a chamber, the solvent is instantaneously vaporized immediately after spinning to form a reticulated fiber, and then a web is formed from the reticulated fiber,
According to this method, the web is subjected to a partial thermocompression bonding process. According to this method, the web has high strength, is highly flexible, has a bacterial barrier property, and has excellent hygroscopicity and printability. It is possible to efficiently manufacture a net-like non-woven fabric suitable as a material for protective clothing in the hygiene field, interior goods such as carpets, and various life-related materials.

[Procedure amendment]

[Submission date] May 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

[0015]

EXAMPLES Next, the present invention will be specifically described based on Examples. The measurement and evaluation of various characteristics in the examples were carried out by the following methods. Melting point of polymer: Differential scanning calorimeter D manufactured by Perkin Elmer
The melting point was defined as the temperature at which the exothermic value of the melting and absorption heat curve measured using the SC-2 type at a temperature rising rate of 20 ° C./min. Melt index (g / 10 minutes): ASTM D 1
It was measured by the method described in 238 (E). Nonwoven fabric thickness (mm): sample length 10 cm, sample width 1
5 samples of 0 cm were prepared, and a load of 4.5 g / cm ² was applied to each sample using a thickness measuring instrument manufactured by Daiei Kagaku Seiki Seisakusho. After standing for 10 seconds, the thickness was measured. The average value of the obtained values was used as the thickness (mm) of the nonwoven fabric. Nonwoven fabric KGSM tensile strength (kg / 5cm): JIS
According strips method according to L-109 6, sample width at 10cm the sample length was measured at a pulling rate of 10cm / min per 10 sample 5 cm, weight per unit area of the average value of the strong tensile obtained 100 g / m ² per Converted to, non-woven KGS
M tensile strength (kg / 5 cm). Tear strength (kg) of non-woven fabric: Elmendorf type tear according to the Penzirum method described in JIS L-1096
It measured using the strength tester . Tensile elongation of the nonwoven fabric (%): JIS accordance L-109 6 strips method described, the specimen-stretching was measured at a speed 10 cm / min per 10 points, resulting tensile pulling a mean value of elongation of the nonwoven fabric Shin The degree (%). Specific surface area of non-woven fabric fibers (m ² / g): BE using a nitrogen adsorption device BELSORP28 manufactured by Nippon Bell Co., Ltd.
Specific surface area (m ²
/ G) was determined. Moisture absorption rate (%) of non-woven fabric: 5 samples were prepared, and this sample was dried using a hot air dryer at a treatment temperature of 80 ° C and a treatment time of 24 hours, cooled in a desiccator, and then dried completely. The weight W ₁ (g) was measured. Then, this sample was allowed to stand in a thermo-hygrostat at a temperature of 20 ° C. and a humidity of 65%, and the weight W ₂ when the change in mass with time reached a saturation value
(G) was measured, and the moisture absorption rate (%) of the nonwoven fabric was determined from the obtained weight value by the following formula (7). Moisture absorption nonwoven (%) = [(W ₂ / W ₁₎ -1] × 100 (7)

Claims (4)

[Claims] 1. A solution prepared by dissolving and mixing a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B in the same bath at high temperature and high pressure using a solvent and water as a spinning solution, which is prepared under autogenous pressure or After being spun into the atmosphere through a spinning hole having a pressure drop chamber under pressure, the solvent is instantaneously vaporized immediately after spinning to form a reticulated fiber, and then a web is formed from the reticulated fiber. A method for producing a reticulated fiber non-woven fabric, which comprises performing a thermocompression bonding treatment. 2. The method for producing a reticulated fiber nonwoven fabric according to claim 1, wherein the polyethylene polymer A and the polyvinyl alcohol polymer B satisfy the following formula (1). 1 ≦ B (wt%) × 100 / [A (wt%) + B (wt%)] ≦ 25 (1) 3. A solution in which the polyethylene-based polymer A, the polyvinyl alcohol-based polymer B, the solvent C and the water D respectively satisfy the following formulas (2) to (4) are used as a spinning solution. 2. The method for producing a reticulated fiber nonwoven fabric according to 2. 5 ≦ A (wt%) + B (wt%) ≦ 25 (2) 40 ≦ C (wt%) ≦ 74 (3) 5 ≦ B (wt%) × 100 / [B (wt%) + D (wt%) ] ≤ 20 (4) 4. A hot embossing roll is used when the web is partially thermocompression-bonded, and the roll temperature T (° C.) and the linear pressure P (kg / cm) are expressed by the following equations (5) and (6), respectively. The method for producing a reticulated fiber non-woven fabric according to claim 1, 2 or 3, wherein the partial thermocompression treatment is performed under a condition satisfying the conditions. [Melting point of polymer −40] ≦ T (° C.) ≦ [melting point of polymer] (5) 0.5 ≦ P (kg / cm) ≦ 50 (6)