JPH03213553A - Ultrafine filament nonwoven cloth - Google Patents

Abstract

PURPOSE:To obtain the subject nonwoven cloth having refined surface form and dense structure by combining a specific bicomponent conjugate filament composed of two kinds of mutually incompatible polymer components with filaments derived from the above filament and having various split states. CONSTITUTION:The objective nonwoven cloth is composed of (a) a bicomponent conjugate filament consisting of a polymer A and an incompatible polymer B having a melting point higher than that of the polymer A by >=30 deg.C and joined to the polymer A in the form of plural segments each having a convex lens-cross section (satisfying the relationships R1/R0<1 and 1<L1/L0<=3 wherein R0 and R1 are the radii of curvature of the polymer B at the convex lens part and L0 and L1 are arc lengths), (b) a filament produced by partially peeling the segment of the polymer B component from the bicomponent conjugate filament, (c) a split filament consisting exclusively of the polymer A component and (d) a split filament consisting exclusively of the polymer B component and having a single fiber fineness of <=0.8 denier (the splitting ratio of the segment consisting exclusively of the polymer B is 30-95%). The fibers are at least partially welded to each other with the polymer A component.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a nonwoven fabric made of ultrafine long fibers.

More specifically, the present invention relates to a nonwoven fabric made of ultrathin long fibers having a delicate surface morphology and a dense structure.

(Prior Art) Nonwoven fabrics have conventionally been used for various purposes such as clothing, industrial materials, civil engineering and construction materials, agricultural and horticultural materials, life-related materials, and medical and sanitary materials. Among these, nonwoven fabrics made of long fibers are widely used because they have higher tenacity and superior productivity compared to nonwoven fabrics made of short fibers. Many attempts have been made to obtain a nonwoven fabric made of long fibers that has a delicate surface and a dense structure. For example, Japanese Patent Publication No. 44-24699.

Special Publication No. 52-30629 and Special Publication No. 621131
Publication No. 6 discloses that a nonwoven fabric composed of fine fibers can be obtained by subjecting a sheet to chemical treatment to dissolve or remove a portion of the polymer constituting the fibers. There is. Also.

Japanese Patent Publication No. 1-47585 and Japanese Patent Publication No. 1-47586
The publication discloses a nonwoven fabric in which a sheet is treated with a high-pressure water stream to split the fibers into ultra-fine fibers, and the fibers are three-dimensionally entangled. It is disclosed that a nonwoven fabric made of ultrafine fibers can be obtained by treatment to remove water-soluble components. However, these nonwoven fabrics or methods for producing nonwoven fabrics have a problem in that the production process is complicated and the polymer needs to be removed, resulting in high production costs. Furthermore, Japanese Patent Publication No. 53-10169 discloses that a nonwoven fabric made of ultrafine fibers can be obtained by puffing a sheet and splitting the fibers. There is a problem that it can be damaged.

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

(Means for Solving the Problems) The inventors of the present invention have arrived at the present invention as a result of intensive studies to solve the above-mentioned problems. In other words, the present invention is as follows.

A split two-component composite long fiber composed of a polymer component A and a segment having two or more convex lens-shaped cross sections made of a polymer component B that is incompatible with the polymer component A; The fineness of a single fiber composed only of the polymer component B developed by splitting the two-component composite filament is 0.8.
A nonwoven fabric composed of split filaments having a 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 and is perpendicular to the fiber axis of the one-split two-component composite filament. Radius of curvature R8 and R19 in the convex lens-shaped portion due to the polymer component in the cross section; arc lengths Lo and Ll of the circular arc;
satisfies the following formulas (1) and (2), the splitting ratio of splittable long fibers consisting of only one polymer component B is at least 30%, and the fibers are at least partially bonded by polymer component A. The gist of the invention is an ultrafine long fiber nonwoven fabric characterized by:

R+/Ro＜1 ■１＜L
r/Lo≦3 ■CRo:
Radius of curvature of an arc not in contact with polymer component A, R0 Radius of curvature of an arc in contact with double polymer component A, Lo: Arc length of an arc not in contact with polymer component A, L: Polymer component A
arc length of the circular arc that is in contact with] Next, the present invention will be described in detail.

In the present invention, the incompatible polymer components A and B both have fiber-forming ability and can be melt-spun using a conventional melt-spinning apparatus. Polymer component A
As for the combination of and B.

Examples include polyester-based and polyamide-based, polyester-based and polyolefin-based, polyamide-based and polyolefin-based, etc. Polyester-based polymers include polyesters such as polyethylene terephthalate and polybutylene terephthalate.

Examples of polyamides include polyamides such as nylon 6, nylon 46, nylon 66, and nylon 610, and examples of polyolefins include polypropylene.

High density polyethylene, linear low density polyethylene.

Examples include polyolefins such as ethylene/propylene copolymers. Further, to the 9-polymers A and B, 9-common additives such as matting agents, heat stabilizers, pigments, or polymer crystallization promoters may be added.

The ultrafine long fiber nonwoven fabric of the present invention is melt-spun split type 2
The component composite long fibers are taken up by a taking means such as an air sucker, deposited on the collection surface of a web conveyor, etc., and the web is processed with a group of smooth-surfaced rolls heated at high line pressure. The fibers made of polymer component B are peeled from the composite filaments to produce split filaments, and at the same time,
It can be produced by at least partially adhering the fibers using fibers made of polymer component A having a low melting point. In addition, the web is treated with a group of unheated rolls with a smooth surface under high line pressure, and the fibers made of the polymer component B having a high melting point are separated from the composite filaments to form split filaments. It can also be produced by at least partially adhering the fibers with fibers made of the low melting point polymer component A using a roll. Replaces heating rolls with smooth surfaces.

A heated embossing roll can also be used. Use a heated embossing roll to make the web.

A nonwoven fabric is obtained by at least partially adhering the fibers with fibers made of low melting point polymer component A.Next, the nonwoven fabric is treated with a group of rolls with a smooth surface under high linear pressure to form high melting point polymer component B. The nonwoven fabric of the present invention can also be created by separating the fibers consisting of composite filaments from composite filaments to produce split filaments. Note that the obtained nonwoven fabric may be subjected to a softening process to improve the flexibility of the nonwoven fabric.

Polymer component B in the present invention needs to have a melting point higher than the melting point of bipolymer component A by 30° C. or more. The melting point of the polymer as referred to in the present invention is measured using a differential calorimeter DSC-2 manufactured by PerkinElmer.

It was determined from a DSC curve obtained by measuring a sample amount of approximately 5 mg and a scanning speed of 20° C./min according to the manual for the device. If the melting point difference between polymer component B and polymer component A is less than 30°C, the nonwoven fabric will shrink due to heat when the web is thermally bonded with a heating roll, resulting in decreased dimensional stability and poor texture of the nonwoven fabric. This is not preferable because it also causes problems such as the bonding temperature range during thermal bonding becomes narrow and temperature control becomes difficult. If the web is thermally bonded with a heated roll whose surface temperature is higher than the melting point of polymer component A, the resulting nonwoven fabric will be film-like or have a hard surface, which is not preferable.

To form a web, the melt-spun fiber bundle is cooled.

It is possible to use drawn continuous fibers obtained by drawing or highly oriented undrawn continuous fibers obtained by high-speed spinning.

The process from spinning to web formation may be a continuous process, and
The web may be created from separately produced drawn filaments or highly oriented undrawn filaments. The web is created by taking these long fibers with a taking means such as an air sucker, forcibly charging them with a charging device to spread the fibers, and depositing them on a collection surface such as a moving web conveyor. can do.

Next, the splittable two-component composite long fiber in the present invention will be explained.

Fig. 1 is a cross-sectional view for explaining the structure of the split type two-component composite filament according to the present invention, and Figs. It is a cross section showing an example of long fibers. In FIG. 1, Ra and R
1 is the radius of curvature at the convex lens-shaped portion of the polymer component in the cross section perpendicular to the fiber axis of the split type two-component composite long fiber.

Ro is the radius of curvature of the arc that is 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, Lo and L are the arc lengths of the arc at the convex lens-shaped portion, and l
LD is the arc length of the arc not in contact with the polymer component A, and +L+ is the arc length of the arc in contact with the polymer component A. Ro and RI were determined based on a cross-sectional photograph of the fiber cross-section magnified 91000 times, assuming a virtual arc that encompasses 90% or more of the arc length of each arc. Also.

Lo and L were obtained by actual measurements from the same enlarged cross-sectional photograph.

In the ultrafine long fiber nonwoven fabric of the present invention, it is necessary that Ro, R, L, and Ll shown in FIG. 1 satisfy the above formulas (1) and (2). If R+/Ro is R, /Ro≧1, L+/Lo is naturally L+/L.

≦1, but in this case, depending on the selected polymer component A and polymer component B, the polymer component A and polymer component B may be separated during the spinning process or the stretching process, and the spinning process or the polymer component B may be separated. Inconveniences such as yarn breakage occur during the drawing process, and when the fibers are formed into a web, the spreadability of the fibers decreases, making it impossible to obtain a uniform web, which is undesirable. If R,+/Ro is Rl/Ro≧1, then Ll/LOi is naturally 1
<L+/Lo, but in this case, depending on the selected polymer component A and polymer component B, the polymer component A and polymer component B will not peel off during the spinning process or the stretching process. When the fibers are formed into a web, a uniform web with good fiber opening properties can be obtained. However, R,
/R, may be R+ /Ro <1, /L, may be L
If + /Lo > 3, it is difficult to treat the web or nonwoven fabric with a group of rolls with smooth surfaces under high linear pressure to separate and split the polymer component A and the polymer component B, so it is preferable. do not have.

The ultrafine long fiber nonwoven fabric of the present invention has a splitting ratio of splittable long fibers consisting of only one polymer component B of at least 30%. This fiber splitting ratio is expressed by dividing the splittable two-component conjugate filament whose Ro, R1°L, and Ll satisfy the above formulas (1) and (2), and the splitting of the splittable two-component conjugate filament. The fineness of a single yarn composed only of the polymer component B is 0.
．． Select any 10 locations on a nonwoven fabric composed of split filaments of 8 denier or less, enlarge the cross section of the nonwoven fabric 100 times and take cross-sectional photographs. The total number of exfoliated segments of polymer component B and the total number of existing segments of polymer component B are determined, and the ratio of the total number of exfoliated segments of polymer component B to the total number of exfoliated segments of polymer component B ( %).

Since the ultrafine long fiber nonwoven fabric of the present invention has a delicate surface and a dense structure, it is necessary that the splitting ratio be at least 30%.

If the splitting ratio is less than 30%, a nonwoven fabric with a delicate surface cannot be obtained.

Further, the split long fibers are composed only of the polymer component B developed by splitting the composite long fibers.

It is necessary that the single yarn fineness is 0.8 denier or less. Even if the splitting ratio is 30% or more, if the single fiber fineness of the splitting long fibers made of 9 polymer component B exceeds 0.8 denier, it is difficult to obtain a nonwoven fabric with a delicate surface and a dense structure. The smaller the single filament fineness, the more difficult it is to obtain a nonwoven fabric with a delicate surface and dense structure.

In the splittable two-component composite long fiber of the present invention, the number of segments having a convex lens-shaped cross section made of one polymer component B must be two or more. If the number of segments is one, the conjugate long fibers may be crimped depending on the spinning conditions or drawing conditions, and the spreadability of the fibers will decrease when forming into a web, making it impossible to obtain a uniform web.

In the present invention, various post-processing conditions such as 1 type of polymers to be combined, 1 combination of polymers, spinning conditions, stretching conditions, peeling and splitting conditions, adhesion conditions, or softening processing can be selected depending on the purpose of use. A nonwoven fabric made of ultrafine long fibers can be obtained.

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

Intrinsic viscosity: Measured at a temperature of 20°C using a mixed solution of equal weights of phenol and tetrachloroethane as a solvent.

Melt index: Measured by ASTM D 123BE method.

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

Tensile strength of a nonwoven fabric in the vertical and horizontal directions. Prepare a measurement sample piece with a width of 33 cm and a length of 10 cm.
It was measured by the strip method described in L1096.

Example 1 Melting point is 128°C, melt index value is 80g/10
Polyethylene polymer with a melting point of 258
A polyethylene terephthalate polymer having an intrinsic viscosity of 0.70 at 100° C. was used as polymer component B, and a split type two-part composite filament was melt-spun through a spinneret having 200 composite spinning holes. During melt spinning, the melting temperature of 9-polymer component A was set to 23
0°C, single hole discharge rate: 0.60 g/min 9 Melting temperature of polymer component B: 285°C, single hole discharge rate: 0.60 g/min [
The ratio (weight ratio) of component A to component B was 1:1. After cooling the spun filament yarn, it is placed under the spinneret at 120 c.
25 filaments were passed through 8 air zippers placed at m positions, sucked and drawn, taken at a speed of 3100 m/min, and forcibly charged with a charging device to open the fibers.

A web was obtained by depositing it on the surface of a moving web conveyor.

The cross-sectional shape 4 of the obtained split type two-component composite filament is a segment having six convex lens-shaped cross sections consisting of one polymer bottom portion A and one polymer bottom portion B, as shown in FIG. It was composed of.

Based on a cross-sectional photograph taken with the fiber cross section magnified 1000 times, a virtual arc that encompasses 90% or more of the six arcs is assumed, Ro, R+, La, and LI are determined, and R, When /Ro and L + /Lo were calculated, R, /R, was OJ, and L, /L, was 1.6. Moreover, this composite long fiber was not split, and the web was uniform.

Next, the resulting web was subjected to fiber splitting and thermal bonding twice using a group of heated rolls with smooth surfaces to obtain a nonwoven fabric. This processing condition is such that the surface temperature of the heating roll group is 115°C.
, the line pressure was 200 kg/Cm.

The obtained nonwoven fabric had a basis weight of 50 g/m', 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 10 arbitrary locations on the nonwoven fabric, enlarge the cross section of the nonwoven fabric 100 times, take cross-sectional photographs, and then calculate the total number of segments of polymer component B that have peeled off from the composite filaments in the 10 cross-sectional photographs. The total number of segments of polymer component B present was determined, and the 10% fiber ratio was determined to be 80%. Also,
The fineness of the split filament consisting only of the polymer component B developed by splitting the composite filament was determined to be 0.
It was extremely thin at 31 denier. This nonwoven fabric had a delicate surface morphology and a dense structure.

Comparative Example 1 Melting point: 125°C, melt index value: 100g/1
A 9-split bicomponent composite continuous fiber was melt-spun in the same manner as in Example 1, except that the 0-minute polyethylene polymer was used as polymer component A, and after cooling, the filament was passed through an air sucker and drawn by suction. 31 (pick up at a speed of 10 m/min,
The fibers were opened by forcibly charging with a charging device and deposited on the surface of a moving web conveyor to obtain a web.

The cross-sectional shape of the obtained split type two-component composite long fiber was
As shown in the figure, it was composed of six segments each having a convex lens-shaped cross section, each consisting of a single polymer bottom portion A and a double polymer bottom portion B.

Based on a cross-sectional photograph of the fiber cross-section, a virtual arc that encompasses 90% or more of the six arcs is assumed.
Rnl R+ l When LD and Ll were determined and R3/R, and /L were calculated, R2/Ro was 0.3
, L, /L, was 3.2. Also.

This composite long fiber was not split, and the web was uniform.

Next, in the same manner as in Example 1, the resulting web was subjected to fiber splitting and thermal bonding twice using a group of heated rolls with smooth surfaces 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 Melting point is 128°C, melt index value is 80g/10
Polyethylene polymer with a melting point of 258
A polyethylene terephthalate polymer having an intrinsic viscosity of 0.70 at 0.01°C was used as polymer component B, and split two-component composite filaments were melt-spun through a spinneret having 625 composite spinning holes. During melt spinning, the melting temperature of 1-polymerized 7-mer component A was set at 230°C, and the single-hole discharge rate was set at 0.20°C.
g/min 1 The melting temperature of polymer component B was 285° C., and the single hole discharge rate was 0.20 g/min [the ratio (weight ratio) of component A to component B was 1:1]. After the spun long fiber yarn is cooled, it is rolled for 250 m/s by a group of heating rollers with a surface temperature of 75°C.
The temperature of this heating roller group and the surface temperature is 90.
The film was stretched at a magnification of 4.0 between heating rollers at a temperature of 4.0°C. The drawn fiber yarn was suctioned through 25 air suckers with 25 filaments each, and the fibers were forcibly charged with a charging device to open the fibers and deposited on the surface of a moving web conveyor to obtain a web.

The cross-sectional shape of the obtained split type two-component composite long fibers was
It was as shown in the figure. Based on a cross-sectional photograph taken of the fiber cross-section magnified 1000 times.

When Rr/Ro and L1/Lo were calculated, R1/
R, is 0.3. L+/Lo was 1.7. Also.

This composite long fiber was not split, and the web was uniform.

Next, the obtained web was subjected to fiber splitting and thermal bonding treatment twice using a heated 8-roll group with a smooth surface to obtain a nonwoven fabric. The processing conditions were such that the surface temperature of the heating roll group was 115° C. and the linear pressure was 200 kg/cm.

The obtained nonwoven fabric had a basis weight of 50 g/m', 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 10 arbitrary points on the nonwoven fabric, enlarge the cross section of the nonwoven fabric 100 times, take a cross-sectional photograph, and calculate the 10% fiber ratio.9
It was 0%. Further, when the fineness of the split filament consisting only of one polymer component B was determined, it was found to be extremely fine at 0.23 denier. This nonwoven fabric had a delicate surface morphology and a dense structure.

Comparative Example 2 Melting point: 132°C, melt index value: 40g/10
One-split two-component composite filaments were melt-spun in the same manner as in Example 2, except that the polyethylene polymer was used as Polymer Component A and the melting temperature was 232°C, and after cooling, a 250 m The fibers were taken up and drawn at a speed of 1/2 min, drawn through an air sucker, and forcibly charged with a charging device to open the fibers and deposited on the surface of a moving web conveyor to obtain a web.

During stretching, a problem occurred in that the composite long fibers were peeled and split on the drawing roller, and the split long fibers were wound around the drawing roller. The obtained web had poor uniformity.

The cross-sectional shape of the obtained split type two-component composite long fiber was
It was as shown in the figure. Based on a cross-sectional photograph taken of the fiber cross-section magnified 1000 times.

When RI/RO and L+/Lo were calculated, R1/
RO is 1.2. LI/Lo was 0.8. Also.

This composite long fiber was not split, and the web was uniform.

Next, in the same manner as in Example 2, the resulting web was subjected to fiber splitting and thermal bonding twice using a group of heated rolls with smooth surfaces to obtain a nonwoven fabric.

The resulting nonwoven fabric has a high splitting ratio of 95%.

Although it has a delicate surface morphology, its uniformity is poor.

Moreover, the basis weight was uneven.

Example 3 The nonwoven fabric obtained in Example 2 was subjected to embossing treatment using a heated embossing roll with a smooth surface. The processing conditions were such that the surface temperature of the heating embossing roll was 120° C. and the linear pressure was 30 kg/cm.

The obtained nonwoven fabric has a basis weight of 55 g/m', 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, and has a delicate surface morphology and a dense structure. It was something that I had.

(Effects of the Invention) The ultrafine long-fiber nonwoven fabric of the present invention consists of one-split type two-component composite long fibers and split filament filaments with a single filament fineness of 0.8 denier or less developed by splitting the split-type two-component composite long fibers. It is composed of 1. It has excellent strength, extremely high uniformity,
Because it has a delicate surface morphology and a dense structure, it can be suitably used as a material for bags and envelopes.

Note that the ultrafine long fiber nonwoven fabric of the present invention can be produced efficiently at low cost without requiring complicated production processes as in the past.

1

[Brief Description of the Drawings] Figure 1 is a cross-sectional view for explaining the structure of the split type two-component composite filament according to the present invention, and Figures 2, 3, 4, and 5 illustrate the constituent elements of the present invention. 6 and 7 are cross-sectional views showing examples of splittable two-component conjugate long fibers that do not satisfy the constituent requirements of the present invention. FIGS.

Claims (1)

[Claims] (1) A split two-component composite long fiber composed of a polymer component A and a segment having two or more convex lens-shaped cross sections made of a polymer component B that is incompatible with the polymer component A. , a nonwoven fabric composed of split filament fibers having a single filament fineness of 0.8 denier or less and composed only of the polymer component B developed by splitting the splittable two-component composite filament, The melting point of the combined component B is 30°C or more higher than the melting point of the polymer component A, and the radius of curvature R_0 and R_1 in the convex lens-shaped portion due to the polymer component B in the cross section perpendicular to the fiber axis of the split type bicomponent composite long fiber, Arc length L of circular arc
_0 and L_1 satisfy the following formulas (1) and (2), the splitting ratio of splittable long fibers consisting only of polymer component B is at least 30%, and the fibers are at least partially covered by polymer component A. An ultra-thin long fiber nonwoven fabric characterized by being bonded together. R_1/R_0<1(1) 1<L_1/L_0≦3(2) [R_0: radius of curvature of the arc not in contact with polymer component A, R_1: radius of curvature of the arc in contact with polymer component A,
L_0: Arc length of the arc not in contact with polymer component A, L_
1: Arc length of the arc in contact with polymer component A]