JPH06287851A - 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 partially heat bonding a netlike fibrous web composed of a polyethylenic polymer and a polyvinyl alcoholic polymer. CONSTITUTION:This netlike nonwoven fabric is obtained by carrying out the flash spinning of high-density polyethylene (A) and a polyvinyl alcoholic polymer (B) so as to satisfy 1<=BX100/[A+B]<=25 (A and B are respectively wt.%), providing netlike fiber, containing the polyvinyl alcoholic polymer finely dispersed in the high-density polyethylene and having at least 10m<2>/g specific surface area, forming the netlike fiber into a web and then subjecting the formed web to hot-pressing treatment with embossing rolls. The web is partially heat bonded.

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 absorbs moisture. The present invention relates to a reticulated 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, an ultrafine reticulated fiber nonwoven fabric obtained 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 an autogenous pressure or higher and spun into the atmosphere.
Japanese Patent No. 519 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 a field of application that requires hygroscopicity or printability, for example, because printing or writing is performed using a 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. An attempt is to provide a reticulated fiber nonwoven fabric having barrier properties and excellent hygroscopicity and printability, which is suitable as a material for heat insulating materials, protective clothing in the medical and hygiene field, interior goods such as carpets, and various life-related materials. 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, the present invention is composed of a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B, composed of a reticulated fiber in which the polyvinyl alcohol-based polymer B is finely dispersed in the polyethylene-based polymer A, and The gist of the present invention is a reticulated fiber non-woven fabric, wherein the reticulated fibers are partially thermocompression bonded.

Next, the reticulated fiber nonwoven fabric of the present invention will be described in detail. The reticulated fibers constituting the nonwoven fabric of the present invention are polyethylene-based polymer A and polyvinyl alcohol-based polymer B.
It consists of and. The polyethylene-based polymer A, which is one component of the reticulated fiber in the present invention, is mainly composed of low-density polyethylene having a fiber-forming property, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, or ethylene. Is a copolymerized polyethylene or the like having a melting point of 100 ° C. or higher. These polymers have melting points of 100
If it is less than ℃, it will be melted even by boiling water, and its practicality will be reduced when a non-woven fabric is formed using reticulated fibers.

The polyvinyl alcohol-based polymer B which is another constituent of the reticulated fiber in 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. Copolymerized polyvinyl alcohol or the like copolymerized with 2 mol% or less is preferable. 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, this polymer B
The degree of saponification is not particularly limited, but when it is desired to improve the heat resistance of the nonwoven fabric, the degree of saponification of the polymer is 87 mol% or more, preferably 90 mol% or more, and particularly preferably 95 mol% or more. Good.

The reticulated fiber in the present invention is one in which the polyvinyl alcohol polymer B is finely dispersed in the polyethylene polymer A. The term “finely dispersed” as used in the present invention means that the polyvinyl alcohol-based polymer B is randomly dispersed in the fibers in the form of fine particles having a diameter of about 0.0001 to 0.1 μm or in the form of fibrils. The scattered state of the polyvinyl alcohol-based polymer B is, for example, that the fibers are electron-stained with osmium tetroxide, then embedded with an epoxy resin, trimmed and surfaced, and the embedded block is stained with ruthenium tetroxide. Then, the dyed and fixed fiber is cut into an ultrathin section and observed by a transmission electron microscope at a magnification of about 60,000 times. Since the non-woven fabric of the present invention is composed of the reticulated fibers in which the polyvinyl alcohol polymer B is randomly dispersed in the extremely fine particulate state or the fibril state as described above in the polyethylene polymer A. That is, it will have almost permanent moisture absorption.

In the reticulated fiber of the present invention, it is preferable that the polyethylene polymer A and the polyvinyl alcohol polymer B satisfy the formula (1).
In this reticulated fiber, if the abundance ratio [B × 100 / (A + B)] of the polyvinyl alcohol-based polymer B is less than 1, the hygroscopicity and printability of the reticulated fiber itself are deteriorated, 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 remarkably deteriorated, and especially in the case of a low basis weight of 100 g / m ² or less, its quality is remarkably deteriorated, which is not preferable. Therefore, in the present invention, this abundance ratio is set to 1 to 25, preferably 2 to 20,
Particularly preferably, it is 3 to 10.

The reticulated fiber in the present invention is composed of the above-mentioned two kinds of polymers and has a three-dimensional structure in which fibrils having an equivalent diameter of 0.1 to 10 μm and a specific surface area of at least 10 m ² / g are continuously gathered. It has a structure that spreads like a net like a typical net structure. In this reticulated fiber, the smaller the equivalent diameter of the fibril is, the more dense and flexible the reticulated fiber can be made into a non-woven fabric, and the more the permeable property is reduced while the moisture permeability is sufficiently maintained. You can also The specific surface area (m ² / g) of the reticulated fiber is measured by the BET nitrogen adsorption method. The monomolecular capacity of nitrogen per 1 g of sample fiber, that is, the entire surface of the sample fiber is covered with a monomolecular layer. The amount of adsorbed nitrogen at this time means that the value of the specific surface area is large, which means that the surface area of the sample fiber is large. Therefore, in this case, it can be understood that the reticulation of the sample fiber is progressing. The specific surface area of this reticulated fiber is 10
When it is less than m ² / g, the reticulation of the fibers does not proceed sufficiently and the texture of the nonwoven fabric obtained by using the fibers is remarkably deteriorated, which is not preferable.

The non-woven fabric of the present invention comprises the above-mentioned reticulated fibers, and the reticulated fibers are partially thermocompression bonded. The term "partial thermocompression bonding" means that the constituent fibers of the non-woven fabric are arranged at constant intervals in the regions where the fibers are thermocompression bonded at their fiber intersections. For example, the pressure welding is performed with a specific size and at a specific interval. It is formed by applying heat and pressure using points. This non-woven fabric is high in strength and rich in flexibility because the reticulated fibers are partially thermocompressed, and is more flexible and more durable than conventional pulp-based paper, for example. .

Next, a method for producing the reticulated fiber nonwoven fabric of the present invention will be described. The nonwoven fabric of the present invention uses the polyethylene-based polymer A and the polyvinyl alcohol-based polymer B, and spins a reticulated fiber by a so-called flash-spinning method as described in, for example, US Pat. After that, it can be manufactured efficiently by performing thermocompression bonding treatment. First, a solution obtained by dissolving and mixing the polyethylene-based polymer A and the polyvinyl alcohol-based polymer B in the same bath with the solvent C and the water D 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 structure. 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 and homologs thereof, and alicyclic compounds such as cyclohexane. Hydrocarbons, methylene chloride, carbon tetrachloride, chloroform, 1,1-dichloro-2,2 difluoroethane, 1,2-dichloro-1,1
Halogenated hydrocarbons such as difluoroethane, methyl chloride, ethyl chloride, fluorocarbons, alcohols, esters, ethers, ketones, nitriles, amides, sulfur dioxide, carbon disulfide, unsaturated hydrocarbons such as nitromethane, or mixtures of the solvents mentioned above. Can be used. In recent years, attention has been paid to the protection of the global environment. From this viewpoint, it is particularly preferable to avoid solvents that destroy the ozone layer. Therefore, methylene chloride, 1,1-dichloro-2,2 difluoroethane, 1,2- Dichlor-1,1
The use of difluoroethane is preferable because it does not harm the global environment as has been observed when conventional freon is used as a solvent. When the nonwoven fabric of the present invention is manufactured, water D is used together with the solvent C. The water D dissolves 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.

As the polyethylene-based polymer A, A
Melt index measured by the method described in STM-D-1238 (E) is 0.3 g / 10 minutes or more and 30 g or more.
It is preferable to use one having a high viscosity of / 10 minutes or less.
If the melt index is less than 0.3 g / 10 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. 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, in the spinning solution prepared by dissolving the polyethylene-based polymer A or the solvent, a matting agent, a lightproofing agent, a heatproofing agent, a pigment, a fiber opening agent, which is usually used for fibers, Ultraviolet absorbers, heat storage agents, stabilizers and the like can be added as long as they do not impair the effects of the present invention.

As the polyvinyl alcohol-based polymer B, polyvinyl alcohol having a fiber-forming property or other vinyl group such as ethylene, itaconic acid, vinylpyrrolidone is copolymerized in an amount of 10 mol% or less, preferably 2 mol% or less. Copolymerized polyvinyl alcohol or the like is used, but from the viewpoint of improving the strength of the nonwoven fabric as described above, it is preferable to use one having an average degree of polymerization of 1000 or more, preferably 1500 or more, and particularly preferably 1700 or more. Further, from the viewpoint of improving the heat resistance of the non-woven fabric, it is preferable to use one having a saponification degree of 87 mol% or more, preferably 90 mol% or more, particularly preferably 95 mol% or more.

In consideration of the spinnability in flash-spinning and the properties of the obtained reticulated fiber, the polyethylene-based polymer A, the polyvinyl alcohol-based polymer B, the solvent C and the water D are each used as a spinning solution. It is preferable to use a solution that satisfies the following formulas (2) to (4). 5 ≦ A (wt%) + B (wt%) ≦ 25 (2) 40 ≦ C (wt%) ≦ 74 (3) 5 ≦ B (wt%) × 100 / [B (wt%) + D (wt%) ≦ 20 (4) In this spinning solution, when the concentration of the polymer [A + B] in the spinning solution is less than 5% by weight, when the polymer and the solvent are phase-separated immediately after flash spinning, Since the spun fibrils do not form a continuous structure because the area occupied by the system is small and scattered, and the strength is not improved, on the other hand, when the concentration of the polymer [A + B] exceeds 25% by weight,
Since the concentration of the polymer [A + B] is too high and the dissolution becomes non-uniform, it is not possible to obtain ultrafine fibrils. Moreover, the spun fibers have their fibrils bonded to each other on their side faces and have voids inside. And a 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, the structure in which the fibrils are not continuous is not formed, which is not preferable. Furthermore, when the fraction (%) of the polymer B in [B (wt%) + D (wt%)] is less than 5%, the content of the polymer B in the spun fiber is small. If the hygroscopicity of the fiber itself becomes insufficient, while the fraction (%) of the polymer B in [B (wt%) + D (wt%)] exceeds 20%,
Polymer B gels and the viscosity becomes too high, making it difficult to spin it out, which is not preferable.

Further, when preparing a spinning solution, all the polymers [A + B] are used as solutes, and these are put together with the solvent C and water D in a dissolution apparatus and the solution is prepared by heating and kneading to obtain a solution. The obtained 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. If the inert gas is injected before the temperature of the spinning solution in the dissolving device is raised,
It is more preferable because it can 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 the water D in the dissolution apparatus depend on the viscosity of the polymer, that is, the degree of polymerization, and are difficult to specify unconditionally. 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. Usually, it is preferable that the pressure is 40 kg / cm ² or more and 160 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
It is preferable that the pressure is not less than kg / cm ² and the spinning pressure is 40
If it is less than kg / 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 is not uniform. Therefore, it becomes difficult to stably obtain highly fibrillated reticulated fibers. On the other hand, the spinning pressure is preferably 160 kg / cm ² or less, and when the spinning pressure exceeds 160 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. .

Next, a web is formed using the obtained reticulated fibers, and the reticulated fibers are partially thermocompression-bonded to each other by applying heat and pressure to the web. When forming a thermocompression-bonded portion on a web, for example, an embossing method in which the 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 welding device can be adopted. When this hot embossing roll is used, the processing temperature T (° C) that satisfies the following equation (5) as the thermocompression bonding processing condition
It is preferable to select a linear pressure P (kg / cm) that satisfies the following equation (6). The melting point (° C.) of the polymer in the following formula (5) is the melting point of the polymer having the lowest melting point among the polymers constituting the fiber. The melting point as used herein means the temperature that gives the extreme value of the melting absorption heat curve measured using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elma Co. at a temperature rising rate of 20 ° C / min. [Melting point of polymer −40] ≦ T (° C.) ≦ [melting point of polymer] (5) 0.5 ≦ P (kg / cm) ≦ 50 (6) In this case, the treatment temperature T (° C.) is Melting point of coalescence-40]
If it is less than 1, the strength of the non-woven fabric is not improved because the reticulated fibers are not sufficiently thermocompressed. On the other hand, if the treatment 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.

[0019]

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
Five samples of 0 cm were prepared, a thickness measuring device manufactured by Daiei Kagaku Seiki Seisakusho was used, a load of 4.5 g / cm ² was applied to each sample, and the sample was allowed to stand for 10 seconds, and then the thickness was measured. The average value of the obtained values was defined 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) nonwoven printability: by printing the non-woven fabric with an aqueous ink and oil ink, sharpness and durability of the printing Was evaluated according to the following four levels. For comparison, a commercially available polyethylene-based flash-spun nonwoven fabric “Tyvek, Type 10 (105
6D) ”(registered trademark of Dyupon) was also evaluated. ◎: extremely good, ○: good, △: slightly inferior, ×: inferior

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 with stirring at an appropriate speed. This solution had a total polymer [A + B] concentration of 15% by weight and a polyethylene polymer A / polyvinyl alcohol polymer B weight ratio (A /
B) are mixed as shown in Table 1 with a methylene chloride concentration of 63% by weight and a water concentration of 22% by weight. Then, the internal temperature of the autoclave was 170 ° C and the internal pressure was 100k.
After reaching g / cm ² G, the valve of the autoclave was immediately opened at this internal pressure, that is, the spinning pressure of 100 kg / cm ² G, and the pressure drop chamber was provided. The spinning solution is discharged into the atmosphere through the holes to spun out the reticulated fiber composed of the polyethylene polymer A and the polyvinyl alcohol polymer B, and the spun fiber group is tilted at 45 ° at a position 25 mm away from the spun hole. A web was created by colliding with the provided spread plate. Then, using a hot embossing roll having a pressing area ratio of 17% and a metal roll having a heated and smooth surface, the obtained web was partially heated at a surface temperature of 125 ° C. and a linear pressure of 25 kg / cm. A crimping treatment was performed to obtain a reticulated fiber nonwoven fabric having a basis weight of about 50 g / m ² . 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, M
IX indicates the melt index, MD indicates the vertical direction, and CD indicates the horizontal direction.

[0021]

[Table 1]

The nonwoven fabric of Example 2 and the polyethylene-based flash-spun nonwoven fabric "Tyvek, type 10"
(1056D) "was evaluated for printability. The results are shown in Table 2.

[0023]

[Table 2]

As is clear from Table 1, the non-woven fabrics of Examples 1 to 3 have practical strength and high specific surface area of fibers, excellent hygroscopicity and printability, and have no coloring at all. It was 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. Further, in the nonwoven fabric of Example 4, since the fibers having a high abundance ratio of the polyvinyl alcohol polymer were spun, the fibers were bonded to each other at their side faces and the fibers were not opened uniformly, the hygroscopicity and printability were excellent, but the texture was good. Was low. On the other hand, the non-woven fabric of Comparative Example 1 has practical strength as is clear from Table 1 and has a high specific surface area due to good fibril formation, but is formed from polyethylene polymer alone. It had no hygroscopicity.

[0025]

The reticulated fiber nonwoven fabric of the present invention comprises a polyethylene-based polymer A and a polyvinyl alcohol-based polymer B, and the polyvinyl alcohol-based polymer B is finely dispersed in the polyethylene-based polymer A. It is composed of reticulated fibers, and the reticulated fibers are partially thermocompression bonded, and has high strength, flexibility, bacterial barrier properties, and excellent hygroscopicity and printability, for example, heat retention. Suitable for materials, protective clothing in the medical and hygiene field, interior goods such as carpets, and various life related materials.

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[Procedure amendment]

[Submission date] May 13, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

[0019]

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
Five samples of 0 cm were prepared, a thickness measuring device manufactured by Daiei Kagaku Seiki Seisakusho was used, a load of 4.5 g / cm ² was applied to each sample, and the sample was allowed to stand for 10 seconds, and then the thickness was measured. The average value of the obtained values was defined 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) nonwoven printability: by printing the non-woven fabric with an aqueous ink and oil ink, sharpness and durability of the printing Was evaluated according to the following four levels. For comparison, a commercially available polyethylene-based flash-spun nonwoven fabric “Tyvek, Type 10 (105
6D) ”(registered trademark of Dyupon) was also evaluated. ◎: extremely good, ○: good, △: slightly inferior, ×: inferior

Claims (3)

[Claims] 1. A polyethylene-based polymer A and a polyvinyl alcohol-based polymer B, which are composed of reticulated fibers in which the polyvinyl alcohol-based polymer B is finely dispersed in the polyethylene-based polymer A. A reticulated fiber non-woven fabric, characterized in that reticulated fibers are partially thermocompression bonded. 2. The reticulated 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. The specific surface area of the reticulated fiber is at least 10 m.
The reticulated fiber non-woven fabric according to claim 1 or 2, which is ² / g.