JPH02277820A - Conjugate yarn - Google Patents

Abstract

PURPOSE:To provide conjugate yarn for paper diapers, etc., giving soft feeling and excellent in both bulkiness and mechanical strength, consisting of multi-core type conjugate fiber made up of a polyamide as the island component and a copolyester as the sea component with said two components differing in melting point by a specific amount. CONSTITUTION:The objective conjugate yarn (fiber) made up of (A) as the island component, a polyamide >=1.38 in intrinsic viscosity and (B) as the sea component, a copolyester with its melting point >=30 deg.C lower than that of the above polyamide, at the weight ratio A/B=8/2-2/8, satisfying the relationship: 24<=(Tm<1/2>)/[etae]<2=47 where Tm is melting point of copolyester and etae is its intrinsic viscosity. For the present conjugate fiber, when heat-treated, part of the infusible island component is split and other island component, even in the rest, is separated in a multi-core fashion through the sea component, thus becoming softer and stronger.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to composite fibers used in the field of nonwoven fabrics, and more specifically, provides a nonwoven fabric with a soft texture, excellent bulkiness, and strength. The invention relates to composite fibers for

(Prior art) Nonwoven fabrics have rapidly become widely used in the clothing and industrial materials fields in recent years because they can simplify the manufacturing process, are inexpensive, and can be easily combined with other materials. It's starting to look like this.

With its widespread use, nonwoven fabrics suitable for various uses have come to be produced, and the current situation is that nonwoven fabrics are also being diversified in materials.

For example, polyester, polyamide, polyolefin,
Fibers that have been added to traditionally used materials such as rayon with other functionality, or copolymerized polyesters or polyolefins as disclosed in Japanese Patent Publication No. 6244055 and Japanese Patent Application Laid-Open No. 60-3941.2. A core-sheath type composite fiber having a sheath component of polyester or polyolefin having a higher melting point than that of the sheath component as a core component is used as a nonwoven fabric or a binder.

(Problems to be Solved by the Invention) As mentioned above, nonwoven fabrics made of various core-sheath composite fibers have recently come to be used in large quantities, especially for disposable sanitary materials such as disposable diapers and sanitary napkins. . Regarding this nonwoven fabric for sanitary materials.

Since they are mainly used in the disposable field, they are required to be low in price. However, with the reduction of the nonwoven fabric weight, the strength of the currently known nonwoven fabrics made of core-sheath type composite fibers increases when polyester is used as the core component, but the texture becomes harder (on the contrary). On the other hand, when polypropylene is used as the core component, the strength is high and the texture is soft, but it has the disadvantage of being inferior in bulk.

(Means for Solving the Problems) The present inventors have conducted intensive research to solve the problems and have arrived at the present invention.

That is, in the present invention, a polyamide having an intrinsic viscosity of 1.38 or more is used as an island component, and the temperature is 30"C below the melting point of the polyamide.
A multifilamentary composite fiber comprising a copolymerized polyester having a melting point as low as the above as a sea component, the gist of which is a sea-island composite fiber whose intrinsic viscosity and melting point of the copolymerized polyester satisfy the following formula (1). be.

However, T,; the melting point of the copolyester [η. ]: Intrinsic viscosity of copolymerized polyester The present invention will be explained with reference to the following two drawings.

FIG. 1 shows an example of the cross section of the sea-island composite fiber of the present invention.
In the figure, (B) is the island component, and (A) is the sea component.

As the polyamide of the island component, nylon 6° nylon 6
6, nylon 12, etc., and any of the above-mentioned nylon copolymers can be used. In addition.

There is no problem even if the above-mentioned polyamide contains 1% by weight or less of additives such as a dissipating agent and a heat-resistant agent.

It is important from the viewpoint of softness that the individual island components are separated from each other, and in order to separate the island components of the multifilamentary composite fiber, the intrinsic viscosity of the polyamide is
It is necessary that it is 1.38 or more, and more preferably 1.40 or more. Also, the number of island components is
Although it is determined from a comprehensive viewpoint such as the fineness of the whole fiber, the required nonwoven fabric performance, and economic efficiency, it is generally preferable that the fineness of the whole fiber is 0.7 to 15 deniers, particularly 1 to 6 deniers. , the island component is 2 to 10 in any cross section.
It is preferable that there be more than one.

The sea component is a binder component that is fused by heat treating the nonwoven fabric, while the island component is.

Even during the heat treatment, the fiber shape is maintained and the mechanical performance of the nonwoven fabric is maintained. For this reason, it is necessary for the nonwoven fabric to be strong, with a difference in melting point of 30° C. or more between the one ocean floor portion and the island component.

Next, the melting point T of the copolymerized polyester, which is the sea component, and the intrinsic viscosity [η. ] is another important component in implementing the present invention.

The concept of the intrinsic viscosity of polyamide is similar to that described above, but the intrinsic viscosity of polyester, which is a sea component, is [η]. ], in order to separate and separate the island components, it is preferable that the melt viscosity at the time of spinning is low, and the intrinsic viscosity [η,
〕Is required. but.

If it is too low, spinnability will deteriorate.

The polymer properties of the sea component are closely related to the bulkiness, softness, and strength of nonwoven fabrics, and by using multicore composite fibers with specific intrinsic viscosity and melting point of the sea component, bulkiness,
It has been found that a heat-adhesive composite fiber can be obtained that satisfies all nonwoven fabric properties such as softness, 1 strength, etc.

That is, one of the inventors used several types of copolymerized polyesters with different melting points as the sea component, and determined the intrinsic viscosity [η] of each copolymerized polyester. ] was changed and the spinning temperature and nonwoven fabric heat treatment temperature were studied, and (1) (formula) was derived. In other words, door τ/[η. ]2 is 4
When it exceeds 7, the operability of spinning deteriorates significantly, and
The bulkiness of the nonwoven fabric is reduced. On the other hand, ρ−〉′[η. ]2
If it is less than 24, the softness of the nonwoven fabric will be impaired.

The copolymerized polyester that is the sea component has a melting point T of 100
-200℃ are generally easy to use, and contain polyethylene terephthalate and polybutylene terephthalate as the main components, acid components such as isophthalic acid and adipic acid, and 1,
6-hexanediol, neopentyl glycol, etc.
The polyester is a copolymerized polyester of more than one type, and may contain additives such as a matting agent, a coloring agent, and a heat resistant agent within a range that does not impair the physical properties of the fiber.

The ratio of the island component to the sea component can be changed depending on the desired fiber performance, but generally the weight ratio is 8:
The range of 2 to 2:8 is preferred.

The method for producing the sea-island composite fiber of the present invention is not particularly limited, but one example that is usually used economically will be described below. As shown in Figure 2.

Consists of a combination of a capillary plate (1) and a spinning hole plate (2).

In the capillary plate (1), the sea component (A) and the island component (B
) and the sea component (A) is separated into the polymer drift groove (4)
After.

The polymer guide hole (6) is reached. On the other hand, the island component (B) is
It reaches the polymer guide hole (6) from the inside of the capillary (5).

Both components meet at the lower part of the polymer induction hole (6), are spun out from the discharge hole (7), and are wound up at a predetermined speed. Sea component (A)
The confluence state of the island component (B) and the island component (B) will be described in more detail.

As shown in Figure 3, the sea component is located in the capillary outer groove (
9) from the upper part of the guide hole (6) to the lower part, and on the other hand, the island component flows inside the tube of the capillary (5) and flows into the sea component at the bottom of the guide hole through the tip hole α, thereby forming a multi-core type. Composite fibers are obtained.

The obtained undrawn yarn is drawn based on a predetermined yarn design such as fineness and elongation.

By using a spinneret with a relatively simple structure as described above, the other spinning and drawing conditions can be made using conventionally well-known manufacturing conditions for polyamide fibers and polyester fibers.
There are no special conditions such as spinning temperature, spinning speed, stretching temperature, etc., and the process can be carried out under very general manufacturing conditions.

Next, a nonwoven fabric can be produced using the above-mentioned composite fibers by a conventionally known method for producing long fiber nonwoven fabrics and short fiber nonwoven fabrics. That is, a method for obtaining a nonwoven fabric by cutting composite fibers into short fibers to form a web, passing it through a card machine, and then thermally fusing the fibers in a hot air circulation heat treatment machine. After drawing the filament with an air jet, the filament is opened using a known fiber opening device and collected on a moving endless wire mesh to create a web. Heat pressure welding is performed at ~30℃ lower temperature 1
It can be manufactured by a method of obtaining a subban bonded nonwoven fabric.

In addition to using 100% of the above composite fibers,
Other fibers or adhesives may be used in combination as necessary, depending on the desired performance of the nonwoven fabric.

Just select the combination.

(Function) When the fiber of the present invention is used, the fineness is a normal single yarn fineness of about 0.7 to 15 denier before the fiber opening process for cards etc. is also good, and an excellent nonwoven web can be obtained.

Next, the island component and the sea component are incompatible.

and each island component is independent, and the surroundings of the island component are
Because the fibers are completely covered with the sea component, heat treatment at a temperature higher than the melting point of the sea component can cause the fibers to be partially subdivided into island components, or even if they are not divided, the fiber shape can become irregular. The nonwoven fabric obtained by deforming is bulky and has a soft texture. Furthermore, a nonwoven fabric with excellent strength can be obtained due to the adhesion between the sea components that completely cover the island components.

(Example) The present invention will be specifically described below with reference to Examples. The measurement methods and evaluation methods used in the examples are as follows.

(1) Intrinsic viscosity of polyamide The measurement was performed at 25°C using 96% sulfuric acid.

(2) Intrinsic viscosity of polyester Using a mixed solvent of equal weights of phenol and tetrachloroethane, 2
Measured at 0°C.

(3) Melting point of polyester component The sea-island composite fiber was placed on a real stage attached to a microscope, and the temperature was increased by heating while observing with the microscope, and the temperature at which the fiber began to melt was determined as the melting point of the polyester component.

(4) Tensile strength of nonwoven fabric Width 25mm according to JIS L-1096 strip method
The maximum tensile strength was measured using a nonwoven fabric test piece with a length of 100 mm.

(5) Softness (texture evaluation) A nonwoven fabric with a basis weight of 30 g/m was prepared, and its texture was evaluated using a sensory test.

(6) Eye size Measured according to JIS P-814, 2.

(7) Bulky The thickness of the nonwoven fabric test piece was measured under a load of 2 g/ad using a dial gage gauge manufactured by Daiei Kagaku Seiki Seisakusho.

Examples 1-4. Comparative examples 1 and 2. Unitika's nylon 6 resin (trade name A1030 BRT) with an intrinsic viscosity of 1.45 on the reference side was used as the island component (B), and isophthalic acid copolymerized polyesters having various intrinsic viscosities and melting points shown in Table 1 were used as the sea component (A). ), using the spinneret (429 holes) shown in Figure 2.3,
Introducing nylon 6 so that the number of island components is 4? r6
Component discharge amount 131 g/min, island component discharge it10
9g/min, spinning speed 1100m/min, spinning temperature 260℃
The resulting undrawn yarn was bundled into 350,000 denier bundles and drawn at a drawing temperature of 52° C. and a draw ratio of 2.6.

Next, after crimping with a push-in crimper, 51 l
A 2-denier sea-island composite fiber was obtained.

The composite fibers were supplied to a carding machine to form a nonwoven web.1 The web was heat-treated at 140°C for 1 minute using a suction dryer to obtain the nonwoven fabrics shown in Table 2. In addition, in Comparative Example 2 shown in Table 1, single yarn breakage occurred frequently during spinning, and yarn production could not be completed.

The nonwoven fabrics obtained in Examples 1 to 4 were bulky, soft to the touch, and highly strong.

Table 1 Reference Examples Instead of the composite fiber of Example 1, polyester binder fiber of Unitika 01 Product name: Melty Type 4080
A nonwoven fabric measuring 2 d x 51 mm was prepared under the same conditions as in the example. The obtained performance is shown in Table 2.

The obtained nonwoven fabric had high strength, but poor bulkiness and hard texture.

Table 2 Performance of nonwoven fabric Comparative Example 21: Unable to spin and could not be made into a nonwoven fabric.

(Effects of the Invention) When the composite fiber of the present invention is used in a heat-bonded nonwoven fabric, a portion of the unmelted island component is divided by heat treatment, and other undivided portions are also divided through the sea component. Since the nonwoven fabric has a structure in which the individual island components are separated and independent, a nonwoven fabric that is bulky, soft to the touch, and highly strong can be obtained, and is widely used in disposable sanitary materials.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a cross section of a sea-island type fiber. Second
1 is a sectional view showing an example of a spinneret for obtaining the composite fiber of the present invention, and FIG. 3 is an enlarged view of the lower part of the capillary. 1. Capillary plate 2.
After spinning 3, sea component introduction hole 4. Sea component inflow groove 5, capillary 6. Polymer guide hole 7, polymer discharge hole 8. Capillary tip 9, capillary outer circumferential groove 10. Capillary first patent applicant Yuzo Sendama, agent of Nippon Ester Co., Ltd., patent attorney

Claims (1)

[Claims] (1) A multifilamentary composite fiber comprising a polyamide having an intrinsic viscosity of 1.38 or more as an island component and a copolyester having a melting point 30°C or more lower than the melting point of the polyamide as a sea component, A sea-island composite fiber whose intrinsic viscosity and melting point satisfy the following formula (1). However, T_m; melting point of copolymerized polyester [η_e]
; Intrinsic viscosity of copolymerized polyester 24≦√(T_m)/[η_e]＾2≦47 (1)