JP2791159B2 - Extra-fine long-fiber non-woven fabric - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a nonwoven fabric made of ultrafine long fibers, and more particularly to a nonwoven fabric made of ultrafine long fibers having a fibrous surface morphology and a dense structure. .

2. Description of the Related Art Conventionally, nonwoven fabrics have been used for various purposes such as clothing, industrial materials, civil engineering and construction materials, agricultural and horticultural materials, living related materials, and medical hygiene materials. In particular, nonwoven fabrics made of long fibers are more
It is widely used because of its high strength and excellent productivity. Many attempts have been made to obtain a nonwoven fabric having a delicate surface and a dense structure in the nonwoven fabric made of long fibers. For example, Japanese Patent Publication No. 44-24699, Japanese Patent Publication No. 52-30629 and Japanese Patent Publication No.
It is disclosed that a sheet is subjected to a chemical treatment to dissolve a part of the polymer constituting the fiber, or is dissolved and removed to obtain a nonwoven fabric composed of fine fibers. Japanese Patent Publication Nos. 1-47585 and 1-47586 disclose non-woven fabrics in which a sheet is treated with a high-pressure water stream to split the fibers into ultrafine fibers and three-dimensionally entangled with the fibers. It has been done,
No. 9 discloses that a nonwoven fabric made of ultrafine fibers is obtained by washing the nonwoven fabric with water to remove water-soluble components. However, these nonwoven fabrics or nonwoven fabric production methods have a problem that the production process is complicated and the production cost is high because the polymer must be removed. Further, Japanese Patent Publication No. 53-10169 discloses that a nonwoven fabric made of ultrafine fibers is obtained by buffing a sheet and splitting the fibers.
This method has the problem that the constituent fibers are partially damaged.

(Problems to be Solved by the Invention) The present invention is intended to solve the above problems and provide a nonwoven fabric made of ultrafine long fibers having a delicate surface morphology and a dense structure.

(Means for Solving the Problems) The present inventor has conducted intensive studies in order to solve the above problems,
The present invention has been reached. That is, the present invention relates to a polymer component A
A bicomponent conjugate fiber composed of two or more segments having a convex lens-shaped cross section composed of a polymer component B incompatible with the polymer component A; A two-component conjugate long fiber in which a segment composed of the united component B is partially peeled off; a split long fiber composed of only the polymer component A that is developed by dividing the two-component conjugate long fiber; and the polymer component B A non-woven fabric comprising split filaments having a single fiber fineness of 0.8 denier or less, wherein the melting point of the polymer component B is 30 ° C. or more higher than the melting point of the polymer component A; The radii of curvature R ₀ and R ₁ and the arc lengths L ₀ and L ₁ at the convex lens-shaped portion by the polymer component B in the cross section perpendicular to the fiber axis of the long fiber satisfy the following formulas, and the polymer component B The split ratio of the segment consisting of 30% or more and 95% or less And an ultrafine long-fiber nonwoven fabric characterized in that the fibers are at least partially adhered by the polymer component A.

R ₁ / R ₀ <1 ... 1 <L ₁ / L ₀ ≤3 ... [R ₀ : radius of curvature of an arc not in contact with polymer component A, R ₁ :
Radius of curvature of an arc in contact with polymer component A, L ₀ : arc length of arc not in contact with polymer component A, L ₁ : arc length of arc in contact with polymer component A] Will be described in detail.

The incompatible polymer components A and B in the present invention are:
Each of them has a fiber forming ability and can be melt-spun using an ordinary melt-spinning apparatus. Examples of the combination of the polymer components A and B include polyester-based and polyamide-based, polyester-based and polyolefin-based, and polyamide-based and polyolefin-based. Examples of the polyester-based polymer include polyethylene terephthalate,
Polyesters such as polybutylene terephthalate and polyamides such as nylon 6, nylon 46, nylon 66,
Polyamides such as nylon 610 and polyolefins include polyolefins such as polypropylene, high-density polyethylene, linear low-density polyethylene, and ethylene / propylene copolymer. In addition, polymer components A to B
May be added with additives such as a normal matting agent, a heat stabilizer, a pigment or a polymer crystallization accelerator.

In the ultrafine long-fiber nonwoven fabric of the present invention, the melt-spun bicomponent conjugate long fibers are taken up by a take-up means such as an air sucker, deposited on a collecting surface of a web conveyor or the like, and the web is heated at a high linear pressure. The fibers composed of the high-melting polymer component B are at least partially peeled from the composite filaments by treating with a group of rolls having a smooth surface to form split filaments, and at the same time, the fibers composed of the low-melting polymer component A Can be produced by at least partially bonding fibers. Further, the web was treated with a non-heated surface smooth roll group at a high linear pressure, and once a polymer component B having a high melting point was used.
By splitting the fibers of the composite filaments from the composite filaments to obtain split filaments, and then bonding the fibers at least partially with fibers of the low-melting polymer component A using a heating roll. . A heated embossing roll can be used instead of a heating roll having a smooth surface. The web is heated using an embossing roll, and the fibers are at least partially adhered to each other with a fiber composed of a polymer component A having a low melting point to obtain a nonwoven fabric. By the treatment, the fiber composed of the polymer component B having a high melting point is separated from the composite filament to obtain split filaments, and the nonwoven fabric of the present invention can be produced. The obtained nonwoven fabric may be subjected to a softening process for improving the flexibility of the nonwoven fabric.

The polymer component B in the present invention needs to have a melting point higher than the melting point of the polymer component A by 30 ° C. or more. The melting point of the polymer referred to in the present invention is determined by using a DSC-2 type differential calorimeter manufactured by Perkin Elmer Co. according to the manual of the apparatus.
It was determined from a DSC curve obtained by measuring the sample amount at about 5 mg and the scanning speed at 20 ° C./min. If the difference between the melting points of the polymer component B and the polymer component A is less than 30 ° C., when the web is heat-bonded with a heating roll, the nonwoven fabric is thermally contracted, the dimensional stability is reduced, and the hand of the nonwoven fabric is deteriorated. It is not preferable because there are problems such as that the temperature range becomes narrow and the temperature control becomes difficult during thermal bonding. Web to polymer component A
Heat bonding with a heating roll having a surface temperature equal to or higher than the melting point is undesirable because the resulting nonwoven fabric becomes a film or has a hard surface.

For web formation, drawn filaments obtained by cooling and drawing a melt-spun fiber bundle or highly oriented undrawn filaments obtained by a high-speed spinning method can be used. The process from spinning to web formation may be a continuous process, or the web may be made from a separately manufactured drawn long fiber or a highly oriented undrawn long fiber. The web is created by taking up these long fibers with a take-up means such as an air sucker, forcibly charging with a charging device, opening the fibers, and depositing the fibers on a collecting surface of a moving web conveyor or the like. be able to.

Next, the bicomponent composite long fiber according to the present invention will be described.

FIG. 1 is a cross-sectional view for explaining the structure of a bicomponent conjugate filament according to the present invention. FIGS. 2, 3, 4 and 5 are examples of bicomponent conjugate filaments satisfying the constitutional requirements of the present invention. FIG. In FIG. 1, R ₀ and R ₁ are the radii of curvature at the convex lens-like portions due to the polymer component B in the cross section perpendicular to the fiber axis of the bicomponent bicomponent fiber, and R ₀ is the polymer component A.
Radius of curvature of the arc not in contact with the polymer component A, R ₁ is the radius of curvature of the arc in contact with the polymer component A, L ₀ and L ₁ are the arc length of the arc in the convex lens-like portion, and L ₀ is the polymer component arc length of the arc that is not in contact with a, L ₁ is the arc length of the arc that is in contact with the polymer components a. R ₀ and R ₁ are 90% of the arc length of each arc based on the cross-sectional photograph taken at 1000 times magnification of the fiber cross section
The above is obtained by assuming a virtual arc that includes the above. L ₀ and L ₁ were obtained by actual measurement from the enlarged cross-sectional photograph.

The ultrafine long-fiber nonwoven fabric of the present invention has R ₀ and R ₀ shown in FIG.
It is necessary that R ₁ , L ₀ and L ₁ satisfy the above and the formula. If R ₁ / R ₀ is R ₁ / R ₀ ≧ 1, L ₁ / L ₀ is naturally L ₁ / L ₀ ≦
However, in this case, depending on the selected polymer component A and polymer component B, the polymer component A and the polymer component B are separated in the spinning step or the drawing step, and the spinning step or the drawing step is performed. Inconveniences such as thread breakage occur in the process, and when the web is formed, the fiber opening property is reduced and a uniform web cannot be obtained, which is not preferable. If R ₁ / R ₀ satisfies R ₁ / R ₀ ≧ 1, L ₁ / L ₀ naturally becomes 1 <L ₁ / L _{0. In} this case,
Depending on the polymer component A and the polymer component B to be selected, the polymer component A and the polymer component B are used in the spinning step or the drawing step.
Is not peeled off, and a uniform web with good fiber opening properties can be obtained when the web is formed. However, R ₁ / R ₀ is _{R 1 / R 0 <L 1} / L 0 be a 1 L ₁ / L _0> 3
In this case, it is difficult to separate the polymer component A and the polymer component B by treating the web or the nonwoven fabric with a group of rolls having a high linear pressure and having a smooth surface, which is not preferable.

In the ultrafine long-fiber nonwoven fabric of the present invention, the splitting ratio of the segment composed of the polymer component B is 30% or more and 95% or less. The split ratio is defined as a bicomponent conjugate filament in which R ₀ and R ₁ , L ₀ and L ₁ satisfy the above and the formula, and a segment composed of the polymer component B from the bicomponent conjugate filament, which is partially separated. The obtained bicomponent conjugate filaments, the split filaments composed only of the polymer component A developed by splitting the bicomponent composite filaments, and the single-fiber fineness composed of the polymer component B only have a fineness of 0.8. Select any 10 places of the non-woven fabric composed of split filaments of denier or less, magnify the cross section of the non-woven fabric by 100 times and take a cross-sectional photograph.
The total number of segments of the polymer component B peeled off from the conjugate long fiber and the total number of segments of the existing polymer component B are obtained and calculated. It represents the ratio (%) of the total number of segments of the combined component B.

The ultrafine long-fiber nonwoven fabric of the present invention has a splitting ratio of 30% or more and 95% or less, and when the splitting ratio is less than 30%, a nonwoven fabric having a delicate surface morphology and a dense structure is obtained. Can not do.

In addition, split filaments composed solely of the polymer component B developed by splitting the composite filaments have a single-fiber fineness.
0.8 denier or less. Even if the splitting ratio is 30% or more, it is difficult to obtain a nonwoven fabric having a delicate surface morphology and a dense structure if the single-filament fineness of the splitting filament made of the polymer component B exceeds 0.8 denier. The smaller the single yarn fineness, the more a nonwoven fabric having a delicate surface morphology and a dense structure can be obtained.

In the bicomponent bicomponent fiber of the present invention, the number of segments having the convex lens-like cross section composed of the polymer component B must be two or more. If the number of this segment is 1
If it is a single piece, crimping occurs in the conjugate long fiber depending on spinning conditions or drawing conditions, and when the web is formed, the openability of the fiber is reduced and a uniform web cannot be obtained.

In the present invention, various kinds of post-processing conditions such as types of polymers to be combined, compounding of polymers, spinning conditions, drawing conditions, peeling splitting conditions, bonding conditions, and flexible processing are selected according to the purpose of use. Thus, an ultrafine long-fiber nonwoven fabric can be obtained.

(Example) Next, the present invention will be specifically described based on examples.
Various characteristics in the examples were measured by the following methods.

Intrinsic viscosity: Measured at a temperature of 20 ° C using an equal weight mixture of phenol and ethane tetrachloride as a solvent.

Melt index: Measured by ASTM D 1238 E method.

Melting point: Determined from a DSC curve obtained by measuring the amount of a sample at about 5 mg at a scanning rate of 20 ° C./min using a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer.

Tensile strength in the vertical and horizontal directions of the nonwoven fabric: A test specimen having a width of 3 cm and a length of 10 cm was prepared and measured by the stripping method described in JIS L-1096.

Example 1 Composite spinning using a polyethylene polymer having a melting point of 128 ° C. and a melt index value of 80 g / 10 min as a polymer component A, and a polyethylene terephthalate polymer having a melting point of 258 ° C. and an intrinsic viscosity of 0.70 as a polymer component B The bicomponent composite filament was melt-spun through a spinneret having 200 holes. In melt spinning,
Polymer component A has a melting temperature of 230 ° C and a single hole discharge rate of 0.60 g /
The melting temperature of the polymer component B is 285 ° C, and the single hole discharge amount is 0.6
0 g / min (the ratio (weight ratio) of component A to component B is 1 to 1). After cooling the spun long fiber yarn, it is placed under the spinneret.
25 filaments are sucked and drawn through each of eight air satskas arranged at a position of 0 cm, drawn, drawn at a speed of 3100 m / min, and forcibly charged by a charging device to open and move the fibers. The web was obtained by depositing on the web conveyor surface.

As shown in FIG. 3, the cross-sectional shape of the obtained bicomponent composite long fiber is composed of a polymer component A and a segment having six convex lens-shaped cross sections composed of a polymer component B. Was something. Based on the cross-sectional photograph taken by magnifying the fiber cross section by 1000 times, assuming a virtual arc including 90% or more of the six arcs, R ₀ , R ₁ , L _0, and L ₁ are defined. R ₁ / R ₀ and L ₁ / L ₀ were calculated, R ₁ / R ₀ was 0.3, L ₁ / L ₀
Was 1.6. The composite filament was not split, and the web was uniform.

Next, the obtained web was subjected to a score line / heat bonding treatment twice using a group of heated flat rolls to obtain a nonwoven fabric. This treatment condition is to set the surface temperature of the heating roll group to 115
° C and the linear pressure were 200 kg / cm.

The obtained nonwoven fabric had a basis weight of 50 g / m ² , a tensile strength in the vertical direction of 5.2 kg / 3 cm, and a tensile strength in the horizontal direction of 3.8 kg / 3 cm. Select any 10 places of the nonwoven fabric and set the cross section of the nonwoven fabric to 10
A cross-sectional photograph was taken by magnifying 0 times, and then, in the ten cross-sectional photographs, the total number of segments of the polymer component B and the total number of the existing segments of the polymer component B separated from the composite filament were obtained. When the split ratio was determined, the split ratio was 80%. This nonwoven fabric includes, in addition to split filaments composed only of the polymer component B, bicomponent composite filaments in which the segment composed of the polymer component B is not peeled off at all,
A bicomponent bicomponent fiber in which a segment composed of the polymer component B is partially exfoliated from the bicomponent bicomponent fiber, and a split fiber composed solely of the polymer component A developed by dividing the bicomponent bicomponent fiber. Was observed. The fineness of the split long fiber composed only of the polymer component B developed by splitting the composite long fiber was determined, and was found to be extremely fine, 0.31 denier. The nonwoven fabric had a delicate surface morphology and a dense structure.

Comparative Example 1 Example 1 except that a polyethylene polymer having a melting point of 125 ° C. and a melt index value of 100 g / 10 min was used as the polymer component A.
In the same manner as described above, the two-component composite filament is melt-spun, cooled, drawn through an air sack through filament, and drawn and drawn.
The fiber was taken up at a speed of 100 m / min, forcibly charged by a charging device to spread the fibers, and deposited on a moving web conveyor surface to obtain a web.

As shown in FIG. 6, the cross-sectional shape of the obtained bicomponent conjugate filament is composed of a polymer component A and a segment having six convex lens-shaped cross sections composed of a polymer component B. Was something. Based on the cross-sectional photograph of the fiber cross section, assuming an imaginary arc including 90% or more of the six arcs, R ₀ , R ₁ , L ₀ and L ₁ are obtained, and R ₁ / R ₀ and L ₁ / L ₀
As a result, R ₁ / R ₀ was 0.3 and L ₁ / L ₀ was 3.2. The composite filament was not split, and the web was uniform.

Next, in the same manner as in Example 1, the obtained web was subjected to splitting and heat bonding twice using a group of heated flat rolls to obtain a nonwoven fabric.

The obtained nonwoven fabric had an extremely low splitting ratio of 11%, and did not have a delicate surface morphology and a dense structure.

Example 2 Composite spinning using a polyethylene polymer having a melting point of 128 ° C. and a melt index value of 80 g / 10 min as a polymer component A, and a polyethylene terephthalate polymer having a melting point of 258 ° C. and an intrinsic viscosity of 0.70 as a polymer component B The bicomponent composite filament was melt-spun through a spinneret having 625 holes. In melt spinning,
Polymer component A has a melting temperature of 230 ° C and a single hole discharge rate of 0.20 g /
The melting temperature of the polymer component B is 285 ° C and the single hole discharge rate is 0.2
0 g / min (the ratio (weight ratio) of component A to component B is 1 to 1). After cooling the spun filament yarn, the surface temperature becomes 75
The film was drawn at a speed of 250 m / min by a heating roller group at a temperature of 250 ° C., and stretched at a magnification of 4.0 between the heating roller group and the heating roller group having a surface temperature of 90 ° C. The drawn fiber yarns were suctioned by passing through 25 filaments through 25 air-suckers, forcibly charged by a charging device to spread the fibers, and deposited on a moving web conveyor surface to obtain a web.

The cross-sectional shape of the obtained bicomponent composite filament was as shown in FIG. The fiber cross section based on a cross-section photograph taken magnified 1000 times, was determined the R ₁ / R ₀ and _{L 1 / L 0, R 1} / R 0 is 0.3, L ₁ / L ₀ 1.7 met Was. The composite filament was not split, and the web was uniform.

Next, the obtained web was subjected to splitting and heat bonding twice using a group of heated flat rolls to obtain a nonwoven fabric. This treatment condition is to set the surface temperature of the heating roll group to 115
° C and the linear pressure were 200 kg / cm.

The obtained nonwoven fabric had a basis weight of 50 g / m ² , a tensile strength in the vertical direction of 7.0 kg / 3 cm, and a tensile strength in the horizontal direction of 5.2 kg / 3 cm. Select any 10 places of the nonwoven fabric and set the cross section of the nonwoven fabric to 10
A cross section photograph was taken at a magnification of 0 times, and the split fiber ratio was determined. The split fiber ratio was 90%. As in Example 1, in addition to the split filaments composed only of the polymer component B, the nonwoven fabric includes a bicomponent bicomponent fiber in which the segment composed of the polymer component B is not peeled off at all. A split length composed solely of the bicomponent conjugate long fiber in which a segment composed of the polymer component B is partially removed from the bicomponent conjugate long fiber, and the polymer component A developed by dividing the bicomponent conjugate long fiber Fiber was observed. The fineness of the split long fiber composed only of the polymer component B was determined to be 0.23 denier, which was extremely fine. The nonwoven fabric had a delicate surface morphology and a dense structure.

Comparative Example 2 A polyethylene polymer having a melting point of 132 ° C. and a melt index value of 40 g / 10 minutes was polymer component A, and its melting temperature was 232 ° C.
In the same manner as in Example 2, except that the bicomponent composite filament was melt-spun and cooled, it was drawn by a heating roller group at a speed of 250 m / min, stretched, and sucked through a filament through an air sack. The fibers were opened by forcibly charging with a charging device and deposited on a moving web conveyor surface to obtain a web.

During stretching, the composite filaments were separated and split on the stretching roller, and the split filaments were wound around the stretching roller. And the obtained web was poor in uniformity.

The cross-sectional shape of the obtained bicomponent composite filament was as shown in FIG. The fiber cross section based on a cross-section photograph taken magnified 1000 times, was determined the R ₁ / R ₀ and _{L 1 / L 0, R 1} / R 0 is 1.2, L ₁ / L ₀ 0.8 met Was. The composite filament was not split, and the web was uniform.

Next, in the same manner as in Example 2, the obtained web was subjected to splitting and heat bonding twice using a heated group of rolls having a smooth surface to obtain a nonwoven fabric.

The obtained non-woven fabric had a high splitting ratio of 95% and had a delicate surface morphology, but was inferior in uniformity and had spots on the basis.

Example 3 The nonwoven fabric obtained in Example 2 was subjected to an embossing treatment using a heated embossing roll. This processing condition is
The surface temperature of the heated embossing roll is 120 ° C and the linear pressure is 30kg /
cm.

The obtained nonwoven fabric had a basis weight of 55 g / m ² , a tensile strength in the vertical direction of 10.7 kg / 3 cm, and a tensile strength in the horizontal direction of 7.9 kg / 3 cm.
It had a delicate surface morphology and a dense structure.

(Effect of the Invention) The ultrafine long-fiber nonwoven fabric of the present invention has a two-component conjugate long fiber and a single-fiber fineness expressed by splitting the two-component conjugate long fiber of 0.
It is composed of split denier fibers of 8 denier or less. It has excellent strength, extremely high uniformity, and has a delicate surface morphology and dense structure, so it is suitable for use as a material for bags and envelopes. be able to.

The ultrafine long-fiber nonwoven fabric of the present invention can be efficiently produced at low cost without requiring a complicated production process as in the related art.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining the structure of a bicomponent conjugate filament according to the present invention. FIGS. 2, 3, 4 and 5 are examples of bicomponent conjugate filaments satisfying the constitutional requirements of the present invention. FIGS. 6 and 7 are cross-sectional views showing examples of bicomponent bicomponent fibers which do not satisfy the constituent requirements of the present invention.

Claims (1)

(57) [Claims] 1. A bicomponent bicomponent fiber comprising a polymer component A and two or more segments having a convex lens-like cross section comprising a polymer component B incompatible with said polymer component A. A splitter composed solely of a bicomponent conjugate filament in which a segment composed of the polymer component B is partially peeled off from the bicomponent conjugate filament, and the polymer component A developed by dividing the bicomponent conjugate filament; A nonwoven fabric composed of long fibers and split filaments having a single-fiber fineness of 0.8 denier or less consisting of only the polymer component B, wherein the melting point of the polymer component B is the melting point of the polymer component A. 30 ° C or higher, 2
The radii of curvature R ₀ and R ₁ and the arc lengths L ₀ and L ₁ at the convex lens-like portion by the polymer component B in the cross section perpendicular to the fiber axis of the component composite long fiber satisfy the following and formulas. An ultrafine long-fiber nonwoven fabric, characterized in that the split ratio of the segment comprising the component B is 30% or more and 95% or less, and the fibers are at least partially adhered by the polymer component A. R ₁ / R ₀ <1 ... 1 <L ₁ / L ₀ ≤3 ... [R ₀ : radius of curvature of an arc not in contact with polymer component A, R ₁ :
Radius of curvature of an arc in contact with polymer component A, L ₀ : arc length of arc not in contact with polymer component A, L ₁ : arc length of arc in contact with polymer component A]