JPH04126862A - High-tenacity nonwoven fabric partially thermally bonded under pressure - Google Patents

Abstract

PURPOSE:To obtain the title nonwoven fabric having excellent tensile strength and tear strength by combining a low-melting component comprising a polyamide-based thermoplastic resin composition with a high-melting component comprising a polyester-based thermoplastic resin composition a specific state and fusing. CONSTITUTION:The objective nonwoven fabric which is nonwoven fabric comprising two kinds of filaments of (A) a low-melting component composed of a polyamide-based thermoplastic resin composition and (B) a high-melting component comprising a polyester-based thermoplastic resin composition, wherein the component B is wholly covered with the component A in <=2.1 thickness, partially having linked parts thermally bonded under pressure, wherein the linked parts have 30-100% fiber volume and unlinked parts have <=50% fiber volume, having >=3g/denier single fiber denier of conjugated yarn after thermal bonding under pressure and satisfying correlation shown by the formula (y is tensile strength per g weight of 1m<2> nonwoven fabric; x is tear strength per g weight of 1m<2> nonwoven fabric).

Description

[Detailed description of the invention] [Industrial application field] TECHNICAL FIELD The present invention relates to highly tenacious nonwoven fabrics.

More specifically, it relates to a partially thermocompression-bonded, high-strength nonwoven fabric with excellent tensile strength and tear strength.

[Conventional technology]

Conventionally, nonwoven fabrics have been known in which a part or all of the fiber surface is covered with a low softening point polymer to give the fibers adhesive properties, a web is formed from the fibers, and the adhesive property is made apparent by heating or other means. (Japanese Patent Publication No. 42-21318, Japanese Patent Publication No. 43-1776).

In addition, a partially heat-bonded nonwoven sheet made of long fibers with a two-component core-sheath structure that is suitable for self-fusion and processing into a bag shape or the like is known (Unexamined Japanese Patent Publication No. 1986-1
65564).

In addition, we use a blend of linear low-density polyethylene and crystalline polypropylene as the sheath component, and use a partially heat-adhesive nonwoven fabric with low basis weight, high strength, and good texture that is suitable for diaper lining, etc. has been proposed by the same applicant as JP-A-63-165564 (JP-A-63-2
27814).

In addition, in order to develop a pleasant feel and appearance as well as high abrasion resistance and good tensile strength and tear strength, the - component is made from a multi-component continuous filament that becomes tacky under conditions where other components are not substantially affected. A lightweight nonwoven fabric whose structure is bonded at a large number of bonding points by a component capable of becoming adhesive, and a method for producing the same have been proposed (Japanese Patent Application Laid-Open No. 49-1971).
-47676).

[Problem to be solved by the invention]

As mentioned above, nonwoven fabrics made of composite filaments in which a high-melting point component is covered with a low-melting point component and partially bonded by thermocompression have been known. Non-woven fabric with good texture ■ High tensile and tear strength.

However, in the examples in these publications, the tensile strength is about 150 g/g/m2 in 3 cm (Japanese Patent Application Laid-Open No. 63-227814), and there is no description about the tearing strength.

On the other hand, in recent years, as the uses of nonwoven fabrics have diversified, the performance required of nonwoven fabrics has also become more sophisticated. Especially related to civil engineering, such as horizontal and vertical drains, slope protection materials, road construction mats, etc.
Nonwoven fabrics with excellent tensile strength and tear strength are increasingly required for construction-related applications such as vegetation cloaks, concrete curing mats, waterproofing/soundproofing materials, and heat-insulating house covering materials.

However, as shown by the circle in Figure 1, in conventional nonwoven fabrics, those with high tensile strength have low tearing strength, and conversely, those with high tearing strength have low tensile strength. Even in the method of joining fibers, the tensile strength is yg/3cm/g/ffl, and the tearing strength is x g/g.
/+1? Therefore, a nonwoven fabric that satisfies both high tensile strength and high tearing strength at the same time has not yet been obtained, and obtaining such a nonwoven fabric is a pressing issue in the industry. Met.

The object of the present invention is to provide a material that has both high tensile strength and tear strength and is extremely useful as an industrial material such as civil engineering materials and construction materials.
In other words, as shown in FIG. 1, y5·X≧2. OXIO
Our goal is to provide nonwoven fabrics that are

[Means to solve the problem]

The present inventors have discovered the surprising fact that high tensile strength and high tear strength can be simultaneously satisfied by satisfying specific requirements in a core-sheath type composite long fiber nonwoven fabric.

Patent application 01-'1431 by the same inventor as the inventor of the present application
In No. 23, a high melting point thermoplastic resin composition is used as a core component,
We have proposed a high-strength nonwoven fabric partially bonded by thermocompression using a core-sheath type composite fiber whose sheath component is a thermoplastic resin composition having a melting point 50°C or more lower than this. Here, as a joining method for nonwoven fabrics, when joining by applying pressure at a temperature above the softening point of the sheath component and below the melting point, the difference in melting point between the core component and the sheath component is 50
°C or higher, but as a result of intensive research, we found that if a polyester thermoplastic resin composition is used as the high melting point component and a polyamide thermoplastic resin composition is used as the low melting point component, polyamide The present invention was based on the discovery that the thermoplastic resin composition exhibits high tensile strength and high tearing strength even when the melting point difference between the sheath component and the core component is less than 50°C because it is a tough and adhesive resin. This is what we have come to.

That is, the present invention provides a nonwoven fabric made of a long fiber nonwoven fabric, in which the long fibers constituting the nonwoven fabric are made of two types of thermoplastic resin compositions having different melting points, and the low melting point component is made of a polyamide thermoplastic resin composition. It is a composite fiber in which the high melting point component is made of a polyester thermoplastic resin composition, the low melting point component has a thickness of 2.1 μm or less and completely covers the surface of the high melting point component, and the nonwoven fabric partially covers the surface of the high melting point component. It has a bonded part thermo-compressed and a non-bonded part extending between the bonded parts, and the fiber volume occupation rate at the bonded part is 30% or more.10
less than 0%, and the fiber volume occupancy in the non-bonded part is 50%
or less, and the fiber volume occupancy in the bonded portion is greater than the fiber volume occupancy in the non-bonded portion, and the single fiber strength of the composite fiber after heat-compression bonding to form a nonwoven fabric is 3 g/denier or more. , and the tensile strength and tear strength of the nonwoven fabric satisfy the following formula: A highly strong nonwoven fabric partially bonded by thermocompression.

y5・X≧2X10” y: 1rrf Tensile strength per gram of nonwoven fabric weight x:
The tear strength is per 1 m2 of nonwoven fabric and 1 gram of weight.

The present invention will be explained in detail below.

The basic idea of the present invention is to provide the sheath component of the long fibers constituting the nonwoven fabric with a bonding function between the fibers, and to provide the core component with the mechanical function of the nonwoven fabric.

Therefore, the basic requirement is that it is a so-called core-sheath composite fiber in which the low melting point component completely covers the surface of the high melting point component, and the low melting point component does not completely cover the surface of the high melting point component. In this case, strong adhesion between the fibers cannot be obtained at the contact points between high melting point components and low melting point components, and at the contact points between high melting point components and high melting point components. It is difficult to obtain highly strong nonwoven fabrics.

The thermoplastic resin composition used in the present invention is a general term for synthetic polymers that can be melt-spun, and examples of polyester-based compositions include, for example, polyethylene terephthalate,
Polybutylene bibenzoate, polypropylene terephthalate, polypentylene bibenzoate, 3,3-bis(
Polyester of p-oxyphenyl)pentane and terephthalic acid, 212-bis(3-methyl4-oxyphenyl)propane and polyester of terephthalic acid, 2.2
- Polyester of bis(P-oxyphenyl)pentane and isophthalic acid, polyester of bisphenol A and terephthalic acid or isophthalic acid, polyethylene-2,
Homopolyesters such as 6-naphthalenedicarpoxylate or copolymerized components thereof such as ethylene glycol, propylene glycol, butanediol, xylylene glycol, bisphenol A, diethylene glycol, polyethylene glycol, polypropylene glycol, adipic acid, sebacic acid, phthalic acid, Isophthalic acid, 2,
Polyester resins such as those copolymerized with 6-naphthalene dicarboxylic acid, p-oxyethoxybenzoic acid, glycolic acid, etc., and polyamides include, for example, poly-ε-
polyamides from ω-amino acids, such as caproamide,
ω, ω′ ~ diamines and ω such as polyhexamethylene adipamide.

Examples include polyamide-based resins such as homopolymers of polyamides with ω'-dicarboxylic acids and copolymers thereof.

The thermoplastic resin composition used in the present invention may be composed of these single components or may be a blend of these components. Further, depending on the purpose, pigments, heat stabilizers, ultraviolet absorbers, flame retardants, etc. may be mixed.

The tear strength of a nonwoven fabric is not well understood, but it is thought to be determined by the degree of absorption of tearing stress applied to the nonwoven fabric. When stress is applied to a nonwoven fabric, the joints between the fibers are destroyed before the fibers that make up the nonwoven fabric are cut and destroyed, and when the bonds are separated and the degree of freedom of the fibers increases, the stress is concentrated at a single point within the nonwoven fabric. It is thought that high tearing strength is developed because it is not concentrated and is relaxed.

Therefore, for the nonwoven fabric composed of core-sheath composite fibers used in the present invention, a combination of high-melting point components and low-melting point components, that is, resins that are likely to cause peeling at the interface between the core component and the sheath component, is selected. If the composite fiber itself is structured so that peeling occurs easily at the interface between the core component and sheath component, peeling will occur from the interface between the core and sheath when tear stress is applied, increasing the degree of freedom of the fiber. It is believed that the tear strength of the nonwoven fabric can be increased.

In the nonwoven fabric composed of a core-sheath composite fiber made of a combination of a polyester thermoplastic resin composition and a polyamide thermoplastic resin composition used in the present invention, a peeling phenomenon easily occurs at the interface between the core component and the sheath component. High tear strength is developed.

In order to obtain the highly strong partially thermocompression bonded nonwoven fabric of the present invention, the strength of the single yarn (-fibers) after thermocompression bonding to form the nonwoven fabric is 3.0 g/denier or more, And the thickness of the low melting point component forming the sheath of the single yarn is 2.1 μm.
It is essential that the following conditions are met at the same time, and only when these two requirements are met will the nonwoven fabric strength parameter y5·X become 2 and OX 1013 or more.

In other words, the parameter y5·X, which indicates the strength of the partially thermocompressed high-strength nonwoven fabric of the present invention, has a correlation with the single fiber strength of the composite fiber after thermocompression bonding to form the nonwoven fabric, and the low melting point component As shown in Figure 2, which plots only those with a thickness of 2.1 μm or less, as the single yarn strength increases, y5・X increases, and y5・X increases only when the single yarn strength increases to 3.0 g/denier or higher. X≧2. OX
101″ can be satisfied.

In addition, the parameter y5・X has a correlation with the thickness of the sheath component, as shown in Figure 3, which plots only composite fibers whose single fiber strength is 3.0 g/denier or more after thermocompression bonding and forming a nonwoven fabric. As the thickness of the sheath component becomes smaller, y S , X increases, and y S , x≧2
．． In order to satisfy OX 10”, the thickness of the sheath component should be 2
．． It is essential to reduce the thickness to 1 μm or less, and 1.5 μm
It is more preferable to do the following.

The cross-sectional shape of the core component and/or sheath component of the composite fiber used in the present invention is not only circular, but may also be a modified cross-section such as a triangle or quadrangle, or a hollow cross-section. It may also have a multicore structure. The thickness of the low melting point component as used in the present invention refers to the point on the circumference of the high melting point component where the straight line is the minimum when a straight line is drawn from any point on the outer periphery of the low melting point component toward the core component, that is, the high melting point component. Assuming that the collection of is the real outer circumference of the high melting point component, it is the minimum length of a straight line drawn from any point on the real outer circumference toward the outer circumference of the low melting point component.

As an example, a cross-sectional view of a composite fiber schematically shown in FIG. 4 is shown. 1 in the diagonally shaded area (1) downward to the right in the figure corresponds to the thickness of the low melting point component in the present invention.

The single fiber fineness of the composite fiber used in the present invention is not particularly limited, but in order to maintain high tensile strength of the nonwoven fabric,
It is preferable to make it 20 deniers or less.

The partially thermocompressed high-strength nonwoven fabric of the present invention is one in which a bonded part and a non-bonded part exist in the nonwoven fabric, and an intermediate bonded part exists between the bonded part and the non-bonded part. means. For example, there are some in which a non-bonded part surrounds a bonded part via an intermediate bonded part, and conversely, a bonded part surrounds a non-bonded part.

The bonded portion in the present invention refers to a portion where the conjugate fibers constituting the nonwoven fabric are fused together by heat and pressure, resulting in a high fiber density. In addition, a non-bonded part refers to a part where the constituent fibers are not fused to each other, but it is necessary to have an intermediate joint, which is a part where the change in fiber volume occupancy gradually shifts from the joined part to the non-bonded part. . If this intermediate joint does not exist, when stress is applied to the nonwoven fabric, the stress will be concentrated at the boundary between the joint and the non-joint part, and both tensile strength and tear strength will decrease. On the other hand, in the case where an intermediate joint exists (17), stress is dispersed at the intermediate joint, reducing stress concentration on the boundary between the joint and the non-joining part, and as a result, reduction in tensile strength and tear strength can be prevented. As an example, Fig. 5 (A) shows an electron micrograph of the fiber shape of a cross section of a high-strength non-woven fabric at a joint, a non-joint part, and an intermediate joint when viewed diagonally from above, and Fig. 5 (B)
A schematic diagram is shown below. The part (3) in the schematic diagram of FIG. 5(B) is the surface of the joint, and the part (4) is the cross section of the joint. Further, the portion (5) is the surface of the non-bonded portion, and the portion (6) is the cross section of the non-bonded portion. Moreover, the part (7) is the surface of the intermediate joint, and the part (8) is the cross section of the intermediate joint.

The ratio of the actual volume of the conjugate fiber to the apparent volume of the highly strong nonwoven fabric at the joint of the present invention (hereinafter referred to as fiber volume occupancy) is 30% or more and less than 100%. The joints of nonwoven fabric have a large influence on the mechanical properties of the nonwoven, especially the tensile strength. If the fiber volume occupancy is less than 30%, the composite fibers are not close enough to bond with each other, resulting in high tensile strength. You won't be able to get it. In addition, when the fiber volume occupancy reaches 100%, the fibers at the joint deform and form a film, and in extreme cases, holes form in the nonwoven fabric, making it impossible to obtain a highly strong nonwoven fabric with high tensile strength and high tear strength. . In addition, 50% or more8
It is preferably 0% or less.

(Figure 6(A) shows an electron micrograph of the fiber shape in the cross section of the nonwoven fabric in which the fiber volume occupancy is 80% at the joint of the partially thermocompressed highly strong nonwoven fabric of the present invention.) The non-bonded conjugate fibers of the invention play an important role in developing the high tear strength of the high strength nonwoven fabric. That is, it is important to give the fibers a certain degree of freedom so that they can absorb tearing stress applied to the nonwoven fabric.

Therefore, the fiber volume occupancy in the non-bonded part of the present invention is:
It is essential that the content is 50% or less in order to develop a high strength nonwoven fabric, especially high tear strength.

If it exceeds 50%, the fibers in the non-bonded portions are fixed, the degree of freedom decreases, and the ability to absorb tear stress becomes low, resulting in a failure to obtain high tear strength. The fiber volume occupancy in the non-bonded portion is preferably 30% or less. (
FIG. 6(B) shows an electron micrograph of the fiber shape in the cross section of a high-strength nonwoven fabric in which the fiber volume occupancy in the non-bonded portion is 20%. ) However, it goes without saying that the fiber volume occupancy in the bonded area is greater than that in the non-bonded area.

Regarding the ratio f of the area of the entire joint of the present invention to the area of the entire nonwoven fabric (hereinafter referred to as emboss ratio), if this ratio is too small, the number of joints between composite fibers will be too small and the tensile strength will decrease. Moreover, if it is too large, the nonwoven fabric itself becomes vapor-like and the tear strength decreases, so it is preferably 3% or more and 50% or less, and more preferably 10% or more and 30% or less.

In order to obtain the highly strong nonwoven fabric of the present invention, it is preferable that the area of one joint part satisfies the following conditions.

In other words, the joint part is completely surrounded by the non-joint part,
and the diameter of the smallest circle that encompasses the entire joint (hereinafter referred to as D,
) has a valence of 10 or less, the area of one joint is 0.
When it is less than 05-, the bond between the conjugate fibers at the bonded portion becomes insufficient, and not only the tensile strength decreases, but also the surface abrasion resistance of the nonwoven fabric.

On the other hand, if it exceeds 30-, the stress applied to the nonwoven fabric will concentrate on the joints where the degree of freedom of the composite fibers is small, making it easy to break at the joints.As a result, holes will form in the joints and both tensile strength and tear strength will decrease. However, it is preferably from 0.2 to 10.

In addition, if D exceeds 10 cylinders, and if the joint is not surrounded by non-joint parts, if the diameter of the largest circle inscribed in the joint (hereinafter referred to as D2) is less than 0.2 nun, the joint The bonding of the conjugate fibers at the non-woven fabric becomes insufficient, resulting in not only a decrease in tensile strength but also a decrease in the surface abrasion resistance of the nonwoven fabric. On the other hand, if it exceeds 3 mm, the stress applied to the nonwoven fabric will be concentrated at the joints where the degree of freedom of the composite fibers is small, and the joints will easily break, resulting in holes in the joints and a decrease in both tensile strength and tear strength. Preferably 0.3 torso or more 1 m
m or less.

The present invention is a nonwoven fabric made of long fibers, and short line miscellaneous woven fabrics are inferior to long fiber nonwoven fabrics in terms of tensile strength, and as a result, y5·X≧2. A highly strong nonwoven fabric of OX 10 I3 cannot be obtained.

The long-fiber nonwoven fabric can be produced using conventionally known general methods, such as stretching spun composite fibers using air pressure, and then forming filaments using a corona charging method or a frictional charging method used for boat fishing. A method of obtaining a nonwoven fabric web by charging and opening the fibers and then transporting them while depositing them on a moving net-like body, and a method of obtaining a nonwoven fabric web by a method of transporting the composite fibers while depositing them on a moving net-like body, and a method of obtaining the composite fibers by air injection after reaching a predetermined take-up speed with a godet roll or a nelson roll. There is a method of obtaining a nonwoven web by taking it up with a nozzle, dispersing it, opening it, and then depositing it on a moving net-like body.

The high-strength nonwoven fabric having a partially thermocompressed composite part according to the present invention can be produced by heating the nonwoven web obtained in this way and using an emboss roll in which convex parts are uniformly distributed on the roll surface, and a roll with a smooth surface. By passing the material between the parts and applying pressure, or by passing it through an ultrasonic bonding device,
Obtainable.

The ratio of tensile strength in the strongest direction to the weakest direction (hereinafter referred to as tensile strength ratio), which is a measure of the isotropy of a nonwoven fabric, is not particularly limited in the nonwoven fabric of the present invention, but it is within a practical range. Tear strength is determined by the tear strength in the lowest direction. In other words, even if the nonwoven fabric is torn in the strong direction, it will be torn in the weak direction, and eventually it will be torn in the weakest direction. Therefore, the tensile strength ratio is preferably 2.0 or less, particularly preferably 1.2 or less.

In the present invention, y5・
Using X, this value is 2. A nonwoven fabric with a strength exceeding OX 10" is considered a highly strong nonwoven fabric, but considering its practicality in civil engineering and construction, y, that is, the tensile strength per gram of 1M nonwoven fabric, g/3 cm width/gird, is 20
It is preferable that the tear strength g/g/f is 20 or more per gram of nonwoven fabric weight of 0 or more, that is, 1bo.

[Examples] The present invention will be further explained by examples. The measurement methods or definitions of the characteristic values shown in the examples are as follows.

(1) Melting point <"c>: Using DSC-20 manufactured by Seiko Electronics Co., Ltd.
This is the temperature at the top of the melting point endothermic peak of the DSC curve obtained by collecting 0 mg and raising the temperature from room temperature at a heating rate of 20°C/min.

(2) Tensile strength of non-woven fabric (g/3 crn width/g/bo): According to JIS L 1085 non-woven fabric stain test method, grab a sample piece with a width of 3 cm and set an interval of 10 cm and a tensile speed of 30
The value at break (grams) measured at ±2 cm/min is the In? It is the value obtained by dividing the weight (in grams) per unit and taking the average of the strongest direction and the weakest direction.

(3) Nonwoven fabric tear strength (g/g/bo): JIS L 1
The value (grams) measured by the tear strength C method (Pensulam method) according to the nonwoven fabric stain test method of 085 is divided by the weight M (grams) per gram of the nonwoven fabric, and the I took the average (direct).

(4) Single yarn strength (grams/denier): After thermocompression bonding to make a nonwoven fabric, the conjugate fibers were collected from the nonwoven fabric, and the fibers were tested in accordance with JIS L 1069 fiber tensile test method at a grip interval of 20 mm and a tensile speed. It is the value obtained by dividing the strength at break (in grams) measured at 20 mm/min by the denier of the fiber before the tensile test.

(5) Fiber volume occupancy (%) at the joint: 1r of the nonwoven fabric relative to the value obtained by calculating the apparent volume (e) of one nonwoven fabric from the thickness actually measured from a scanning electron micrograph of the cross section of the nonwoven fabric
Weight per rf (grams) and composite fiber density (g/c
It is the percentage (χ) of the value obtained from the actual volume (rl()) of the composite fiber from

(6) Fiber volume occupancy (%) of non-bonded part: JIS 1.
Based on the thickness measured using a thickness measuring machine under a pressure of 20 gf / ctF + using a thickness measuring machine Preno Surfoot 2ca according to the thickness measuring method of the nonwoven fabric stain test method of 1085, The actual volume (E) of the composite fiber is determined from the weight (grams) per l rrr of the nonwoven fabric and the density (g/era) of the composite fiber for the apparent volume (E) of one nonwoven fabric. It is a percentage (%).

(7) Thickness of low melting point component (μm): This is a value actually measured from a scanning electron micrograph of a cross section of a single fiber in a nonwoven fabric.

(8) Practical performance of nonwoven fabric: Evaluations were made using ○, △, and ×, and the criteria are summarized in Table 1.

(Left below) Examples 1-2 35°C, intrinsic viscosity η 0.62 in ortho-chlorophenol solution, melting point 256°C, density 1.38 (
g/cyfl) of polyethylene terephthalate (hereinafter P
The relative viscosity η of a 1% solution of 99% concentrated sulfuric acid is used as a thermoplastic resin as a high melting point component of the composite fiber and as a thermoplastic resin as a low melting point component of the composite fiber.

2.3, polycaproamide with a melting point of 220°C (hereinafter referred to as N6
) (Example 1) and a copolymer of N6 and polyhexamethylene adipamide (hereinafter referred to as C6PA) with a relative viscosity ηr 3.2 of a 1% solution of 99% concentrated sulfuric acid and a melting point of 204°C. (Example 2).

A composite fiber with a core-sheath structure and a sheath thickness of 1.6 μm was taken at a take-up speed of 5000 m7 minutes, and the single yarn fineness was 4.0.
Denier, the filament is charged using a corona charging method, and after opening, it is deposited on a moving porous strip to form a web, and this web is heated between an embossing roll and a flantro roll with convex portions evenly distributed on the roll surface. Finally, a nonwoven fabric having an embossing rate of 20%, D+10 mm or less, an area of 0.3- of one joint, and a basis weight of 100 g/nr was obtained.

The single fiber fineness of the obtained composite fiber, the thickness of the low melting point component, and the characteristics of the nonwoven fabric include the single fiber strength after thermocompression bonding, fiber volume occupancy, tensile strength, tear strength, parameters y S , x and each thermoplasticity. Table 1 shows the melting point difference between the resin combinations and the heating roll temperature in each example, and the relationship between the tensile strength and tear strength is shown in FIG.

Comparative Example 1 The same PET as in Example 1 was spun alone, and the fibers were opened, deposited, and joined using the same device as in Example 1 to obtain a nonwoven fabric having a basis weight of 100 g/rd. The properties of the obtained nonwoven fabric are shown in Table 2 and FIG.

Examples 3 to 13, Comparative Examples 2 to 4 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the thickness of the low melting point component and the fineness of the single filament were changed, the fibers were opened and deposited using the same equipment as in Example 1, and the heating roll temperature was set to 200'C to obtain a fabric weight of 100 g.
/nf nonwoven fabric was obtained.

Example 1 and the fineness of the obtained composite fiber, the thickness of the low melting point component, and the properties of the nonwoven fabric are shown in Table 3 and FIG.

Examples 14 to 16, Comparative Example 5 The same PET as in Example 1 was used as the high melting point component, and the same N as in Example 1 was used.
6 is a low melting point component, the thickness of the low melting point component is 1.6 μm,
The single fiber fineness was set to 4 denier, the spinning speed was changed, the fibers were spun, and the fibers were opened and deposited using the same equipment as in Example 1, and then heated at a temperature of 20 denier.
Bonded at 0°C and has a fabric weight of 100 g/rr? A nonwoven fabric was obtained. Example 1 and the fineness of the obtained composite fiber, the thickness of the low melting point component, and the properties of the nonwoven fabric are shown in Table 4 and FIG.

Examples 17 to 20, Comparative Example 6.7 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the fibers were spun, opened and deposited using the same equipment as in Example 1, and the upper and lower parts were joined using smooth rolls heated to 200''C to obtain a nonwoven fabric with a basis weight of 100 g/bo.

At this time, the gap between the embossing roll and the flat roll was changed to change the fiber volume occupancy in the bonded and non-bonded areas of the nonwoven fabric. The properties of the obtained nonwoven fabric are shown in Table 5 and FIG.

Examples 21 to 23, Comparative Example 8 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the single fiber fineness was changed and spun, and after opening and stacking using the same device as in Example 1, the heated roll temperature was set to 200.
A nonwoven fabric having a basis weight of 100 g/po was obtained by joining at "C". The fineness of the obtained composite fiber, the thickness of the low melting point component, and the properties of the nonwoven fabric are shown in Table 6 and FIG.

Examples 24 to 26, Comparative Examples 9.10 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the thickness of the low melting point component was 1.6 μm, the single yarn fineness was spun at 4 denier, the fiber was opened and deposited using the same device as in Example 1, and the heating roll temperature was set at 200'C. By changing the embossing ratio and joining, a nonwoven fabric with a basis weight of 100 g/n was obtained. Example 1 and the properties of the obtained nonwoven fabric are shown in Table 7 and FIG.

Examples 27 to 29, Comparative Examples 11.12 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the thickness of the low melting point component was 1.6 μm, the single fiber fineness was spun at 4 denier, and after opening and stacking in the same device as Example 1, the fiber was heated to a temperature of 200 using a heating roll with D1 of 10 mm or less. By changing the area of one joint at °C, a nonwoven fabric having a basis weight of 100 g/m was obtained. Example 1 and the properties of the obtained nonwoven fabric are shown in Table 8 and FIG.

Examples 30 to 32, Comparative Examples 13.14 The same PET as in Example 1 was used as a high melting point component, and the same N as in Example 1 was used.
6 was used as a low melting point component, the thickness of the low melting point component was set to 1.6 μm, the single yarn fineness was spun with a single fiber fineness of 4 denier, and after fiber opening and deposition using the same device as in Example 1, the embossing roll and joint portion with D1 exceeding 10 mm were obtained. Using an embossing roll that is not surrounded by non-bonded parts, they were bonded at a temperature of 200° C. while changing D2 to obtain a nonwoven fabric with a basis weight of 100 g/rd. The properties of this nonwoven fabric are shown in Table 9 and FIG.

Comparative Example 15 A nonwoven web was obtained in the same manner as in Example 1, and then joined at a temperature of 200°C using a heated embossing roll with a engraved pattern such that there is no intermediate joint, to obtain a nonwoven fabric with a basis weight of 100 g/nf. I got it. Example 1 and its nonwoven fabric properties are shown in Table 10 and FIG.

Comparative Example 16 51 long fibers of composite fiber obtained by the same method as Example 1
A nonwoven web was formed by the carding method, and bonded using a heating roll at 200°C in the same apparatus as in Example 1 to obtain a nonwoven fabric with a basis weight of 100 g/rrf. Example 1 and its nonwoven fabric properties are shown in Table 11.

As shown in the above-mentioned examples of the nonwoven fabric of the present invention, the partially thermocompressed high-strength nonwoven fabric of the present invention satisfies all of the following requirements.

In other words, ■ It must be a long fiber ■ There must be a difference in melting point between the low melting point component and the high melting point component ■ The thickness of the sheath component must be 2.1 μm or less ■ Single fiber strength in the nonwoven fabric after thermocompression bonding is 3.0 gram/denier or more ■The fiber volume occupancy of the joined part must be 30% or more and less than 100%.■The fiber volume occupancy of the non-joined part must be 50% or less.■There must be an intermediate joint. Satisfies all requirements.

Examples 1 to 32, which meet all the above requirements, satisfy y5・X and exhibit tensile strength, tear strength, nonwoven surface abrasion resistance, ease of adhesion to the base, ease of application on the water side, and interlayer peeling resistance. do.

The practical performance of Examples and Comparative Examples was evaluated. The results are summarized in Table 12.

〔Effect of the invention〕

In conventional nonwoven fabrics, when the tensile strength is high, the tear strength is low, and on the other hand, when the tear strength is high, the tensile strength is low, and as shown in Fig. 1, y5 x = 2 x 101
However, the high-strength nonwoven fabric of the present invention is located above the curve y5 x = 2X10'', and can develop high tear strength while maintaining high tensile strength. It is.

Such a high-strength nonwoven fabric of the present invention is particularly useful in the fields of civil engineering, construction, and building materials, which require a nonwoven fabric with excellent tensile strength and tear strength.

(Margin below)

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between tear strength and tensile strength of nonwoven fabrics of Examples of the present invention, Comparative Examples, and prior art. FIG. 2 is a graph showing the relationship between the single fiber strength of a composite fiber with a low melting point component having a thickness of 2.1 μm or less and the parameter y5·χ indicating the strength of the nonwoven fabric after thermocompression bonding to form a nonwoven fabric. Third
The figure shows the single yarn strength of 3 after being made into a nonwoven fabric by thermocompression bonding.
．． 2 is a graph showing the relationship between the thickness of a low melting point component forming a sheath of a composite fiber of 0 g/denier or more and the nonwoven fabric strength parameter y5·X. FIG. 4(A) to FIG. 4(E) are cross-sectional views schematically showing various examples of cross sections orthogonal to the fiber axis of composite fibers. Figure 5 (A) is an electron micrograph (100x magnification) showing the shape of the fibers when the cross section of the bonded and non-bonded areas of the nonwoven fabric is viewed diagonally from above, and Figure 5 (B) is A) Schematic diagram. Figure 6 (A) is an electron micrograph (magnification 200x) showing the shape of the fibers in the cross section of a nonwoven fabric with a fiber volume occupancy of 80% at the joints of the nonwoven fabric. An electron micrograph (magnification) showing the shape of fibers in a cross section of a nonwoven fabric with a fiber volume occupancy of 20%. 1 - Low melting point component 2 - High melting point component 3 - Surface of joint 4 - Cross section of joint 5 - Surface of non-joint 6 - Cross section of non-joint 7 - Surface of intermediate joint 8 - Surface of intermediate joint cross section!・-Thickness of low melting point component

Claims (1)

[Claims] 1. A nonwoven fabric made of long fibers, the long fibers that make up the nonwoven fabric are made of two types of thermoplastic resin compositions with different melting points, the low melting point component being a polyamide thermoplastic resin composition, and the high melting point component being a polyamide thermoplastic resin composition. A composite fiber made of a polyester thermoplastic resin composition, in which the low melting point component completely covers the surface of the high melting point component with a thickness of 2.1 μm or less,
And the nonwoven fabric has a joint part partially bonded by thermocompression and a non-joint part extending between the joint part, the fiber volume occupation rate in the joint part is 30% or more and less than 100%, and The fiber volume occupancy of is 50% or less, and the fiber volume occupancy of the bonded portion is greater than the fiber volume occupancy of the non-bonded portion,
In addition, the single fiber strength of the composite fiber after thermocompression bonding to form a nonwoven fabric is 3 g/denier or more, and the tensile strength and tear strength of the nonwoven fabric satisfy the following formula. Made of high strength non-woven fabric. y^5・x≧2×10^1^3 y: 1m^2 Tensile strength per gram of nonwoven fabric weight x: 1m^2 Tear strength per gram of nonwoven fabric weight