JPH0881832A - Polyester splitting type conjugate fiber - Google Patents

Abstract

PURPOSE: To obtain a polyester splitting type conjugate fiber capable of being easily opened in a carding process, capable of being simply split into ultra-fine fibers when processed into a web and subsequently thermally treating the web with a calender roll, etc., and capable of providing nonwoven fabric soft in touch. CONSTITUTION: The characteristics of the polyester splitting type conjugate fiber comprising a polyester polymer A consisting mainly of a polyalkylene terephthalate and a thermoplastic polymer B noncompatible with the polyester polymer A comprises that both the polymers A and B are divided into plural divisions and arranged in the cross section of the fiber and that the dry heat shrinkage rates of the polymers A and B satisfy the following inequalities. (1) (SB-SA)/(NA+NB)<1/2> >=6, (2) SA<=13 [SA; the dry heat shrinkage rate (%) of the polymer A, SB; the dry heat shrinkage rate (%) of the polymer B; NA the number of the divided and arranged divisions of the polymer A, NB: the number of the divided and arranged divisions of the polymer B].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester-based splittable conjugate fiber that is formed into a nonwoven fabric having a soft texture by splitting the fibers when deposited on a web and heat-treated with a calendar roll or the like.

[0002]

2. Description of the Related Art It has been attempted to use thinner fibers or softer fibers in order to obtain products such as nonwoven fabrics having a soft texture.

However, when a non-woven fabric is manufactured by using fibers having a small fineness, clogging or nep is generated in the card process, resulting in poor operability. Generally, in the case of polyester fiber, The use of fibers of less than denier causes problems in the card process as described above.

Also, when soft fibers such as polyolefin fibers are used, if the fineness is decreased, clogging or nep may occur in the card process as in the above case or more, There was a problem that the operability deteriorated.

In order to solve the above-mentioned problems, a fiber is proposed which can be obtained by forming a web in a carding process and then splitting it by various treatments to obtain a nonwoven fabric having a soft texture made of ultrafine fibers. Has been done.

The splittable conjugate fiber disclosed in Japanese Unexamined Patent Publication (Kokai) No. 62-133164 is a non-woven fabric made of ultrafine fibers by splitting the fibers by jetting a high-pressure liquid stream onto the fibers deposited in a web form. The method disclosed in JP-A-62-78213
The splittable conjugate fibers disclosed in JP-A-56-154512 and JP-A-56-154512 are non-woven fabrics made of ultrafine fibers by dissolving one component in a solvent. There is a drawback that the processing speed at the time of processing is slow, the processing steps are complicated, and the cost becomes high.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and is easy to process in the card process, and is easily split by heat treatment with a calender roll or the like after the card process to give ultrafine fibers. It is a technical subject to provide a polyester-based splittable conjugate fiber that can obtain a nonwoven fabric having a soft texture with high productivity.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, a composite fiber in which the difference in dry heat shrinkage between two polymers and the number of divided arrangements are appropriately set is found. The present invention has been found that a soft texture can be imparted to a non-woven fabric because no division occurs in the carding process and the fibers are easily split into ultrafine fibers by the subsequent heat treatment such as calender rolls.

That is, the present invention is a splittable conjugate fiber comprising two components, a polyester polymer A mainly containing polyalkylene terephthalate and a thermoplastic polymer B which is incompatible with the polyester polymer A. In the transverse cross section of the fiber, both the polymers A and B are divided and arranged in a plurality, and the dry heat shrinkage rates of the polymers A and B are as follows:
A gist is a polyester-based splittable conjugate fiber characterized by satisfying the formula.

(S _B −S _A ) / (N _A + N _B ) ^1/2 ≧ 6 S _A ≦ 13 S _A : dry heat shrinkage rate (%) of polymer A, S _B : dry heat of polymer B Shrinkage (%) N _A : number of divided arrangements of polymer A, N _B : number of divided arrangements of polymer B The dry heat shrinkage in the present invention is determined as follows.

The composite fiber which has been stretched and tension heat-treated is passed through a push-in type crimper without crimping,
Cut to about 15 mm, apply a load of 50 mg / d to this composite fiber, measure the fiber length L, and place it in a heating oven at 120 ° C for 15
Leave for a minute.

Then, the fibers split into the polymers A and B by heat are taken out, and the respective fiber lengths l (l _a , l _b ) are set to 50.
The dry heat shrinkage rate of each of Polymer A and Polymer B, which are divided and shrunk, is calculated by the following formula.

Dry heat shrinkage (%) = [(L-1) / L] × 100 The present invention will be described in detail below.

The polyester splittable conjugate fiber of the present invention is a splittable conjugate comprising a polyester polymer A mainly containing polyalkylene terephthalate and a thermoplastic polymer B which is incompatible with the polyester polymer A. A polyester polymer A or a polyester polymer A which is a fiber and constitutes a composite fiber in a cross section of the fiber
Both the thermoplastic polymer B and the thermoplastic polymer B are divided and arranged in plural.

FIG. 1 is a cross sectional view showing an embodiment of the polyester-based splittable conjugate fiber of the present invention. (A) shows four petals of polymer A around polymer B, (b). Is an example in which three polymers A are arranged in a petal-like pattern around the polymer B, and (c) is an example in which the polymers A and B are radially alternately arranged on the circumference. .

Examples of the polyester type polymer A include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Further, a third component is mixed or copolymerized within a range that does not essentially change these properties. It may also contain a small amount of additives such as matting agents, matting agents, antistatic agents and antioxidants.

The thermoplastic polymer B which is incompatible with the polyester polymer A is not particularly limited, but a polyamide polymer such as nylon 6 or nylon 66 or a polyolefin such as polyethylene or polypropylene. Examples include polymers of the system.

The polyester-based splittable conjugate fiber of the present invention is split by heat treatment of a calender roll or the like to cause a difference in the dry heat shrinkage between the two polymers which are divided and arranged so that a boundary surface is displaced. 2 shows a state after splitting of the fiber shown in FIG. 1 (b).

In order to easily split the fibers by heat treatment, the relationship between the number of divided arrangements of the two polymers constituting the composite fiber and the dry heat shrinkage ratio of the two polymers is important.

First, the number of divided arrangements of the two polymers A and B will be described.

In the polyester splittable conjugate fiber of the present invention, the polyester polymer A and the thermoplastic polymer B are the polyester polymer A or the polyester polymer A and the thermoplastic polymer in the cross section of the fiber. Both B are required to be divided and arranged in a plurality.

In the cross section of the fiber, the polyester polymer A needs to be divided and arranged in plural. Since the polyester polymer A has a high rigidity, it is divided into thin fibers in order to impart a soft texture to the nonwoven fabric.

The number of the polyester-based polymer A to be divided and arranged is preferably 4 or more, but if the number of divisions is too large, it becomes difficult to split the fibers, so that it is preferably 4 to 10. In the cross-section of the fiber, the thermoplastic polymer B may or may not be divided and arranged in a plurality, but when a polymer having a high rigidity is used, it is divided and the number of divided arrangements is 4 to 10. It is preferable that

Next, the relationship between the dry heat shrinkage rates of the two polymers A and B will be described.

The splittable conjugate fiber of the present invention must satisfy the above formula. If the formula is not satisfied, polymers A and B
The difference in shrinkage between the two components becomes small, and the heat treatment of the calender rolls makes it difficult for the boundary surface between the two polymers arranged in a divided manner to be displaced, resulting in a low splitting ratio and a nonwoven fabric with a soft texture. Can not.

Further, since the polymer A has a high rigidity, if the dry heat shrinkage S _A of the polymer _A is larger than the dry heat shrinkage S _{B of the} polymer B, the texture of the nonwoven fabric after the fibers are divided becomes hard. Therefore, it is necessary to make the polymer A a low heat shrinkage component, and it is necessary to make the heat shrinkage S _A of the polymer A 13% or less as shown by the formula.

Next, an example of a method for producing the splittable conjugate fiber of the present invention will be described.

First, using a spinneret having a cross section as shown in FIGS. 1 (a), 1 (b) and 1 (c), polymers A and B are used.
Is melt-spun by an ordinary composite spinning machine. Subsequently, the obtained fibers are aligned to form a fiber bundle of 21 to 1,000,000 denier, drawn 2 to 6 times in a drawing step, crimped, heat-treated, and then cut into short fibers.

The dry heat shrinkages of the polymers A and B in the splittable conjugate fiber obtained can be determined by appropriately changing the spinning conditions such as spinning speed, draw ratio and heat treatment temperature.
It can be set to satisfy the formula. It can also be set by appropriately changing the degree of polymerization of the polymer or the polymer to be copolymerized.

Next, an example of a method for producing a nonwoven fabric using the splittable conjugate fiber of the present invention will be described.

The splittable composite fiber is opened at a speed of about 20 to 100 m / min using a roller card, and the basis weight is 15 to 30 g / m.
² web, and then the surface temperature is 100 ~ 2
Using an embossing calender roll in which an embossing roll of 00 ° C and a flat roll are paired, heat treatment is performed at a speed of 15 to 100 m / min to obtain a nonwoven fabric in which the composite fibers are split into the polymers A and B.

[0032]

EXAMPLES Next, the present invention will be specifically described with reference to examples.

The evaluation of each physical property in Examples was carried out by the following methods.

(1) Relative viscosity Using an equal weight mixture of phenol and ethane tetrachloride as a solvent,
It was measured at a concentration of 0.5 g / dl and a temperature of 20 ° C.

(2) Dry heat shrinkage It was measured by the above method.

(3) Splitting ratio Polymer obtained by selecting arbitrary 10 points in the obtained non-woven fabric, enlarging the cross section of the fiber and taking a photograph of the cross section, and then peeling from the composite short fiber in the 10 photographs. The number of divided arrangements of A and the number of divided arrangements of the polymer A were determined and calculated by the following formula.

Divided splitting ratio (%) = (number of divided arrangements of polymer A peeled / total number of divided arrangements of polymer A) × 100 Example: In the schematic diagram of FIG. Number of divided arrangements of A = 6 Total number of divided arrangements of polymer A = 9 Split division ratio (%) = (6/9) x 100 = 67 (4) Texture 10 Softness was 10 by sensory test by 10 panelists. The evaluation was performed in stages and the total score was evaluated.

◎ -85 points or more ○ -84 to 70 points △ -69 to 40 points × -Less than 40 points Examples 1 and 2 and Comparative Examples 1 and 2 PET having a melting point of 256 ° C. and a relative viscosity of 1.38 was polymerized. A, melting point 150 ° C, melt index (MI) value (A
SPM D 1238) has 11 g / min of polypropylene as polymer B and has 319 composite spinning holes and FIG.
(A) is obtained spinneret those of the cross-section shown in (N _A =
4, N _B = 1) was used for composite spinning.

The spinning temperature is 275 ° C., the single-hole discharge amount of the polymer A is
0.28 g / min, single-hole discharge amount of polymer B was 0.20 g / min, and spinning speed was 1000 m / min.

The spun fiber is cooled and drawn to obtain a composite undrawn yarn, and then a 100,000 denier fiber bundle in which the composite undrawn yarn is aligned is drawn, subjected to a tension heat treatment, and then pushed. After crimping with a crimper, it was cut into 51 mm to obtain a splittable conjugate fiber of the present invention. The stretching temperature at this time was 73 ° C., and the stretching ratio and the tension heat treatment temperature were variously changed as shown in Table 1.

The fiber thus obtained had a single yarn fineness of 2 denier.

Subsequently, the short fibrous splittable conjugate fibers were opened at a speed of 20 m / min using a roller card, and the basis weight was 40 g /
After forming the m ² web, the web was subsequently heat-treated at a speed of 20 m / min using an embossing heat calender roll in which an embossing roll and a flat roll were paired to obtain a nonwoven fabric. At this time, the embossing roll has a pressure contact area ratio of 13% and a surface temperature of 140 ° C, and the flat roll has a surface temperature of 120 ° C.
℃ was made.

Table 1 shows the dry heat shrinkage ratio and splitting ratio of the resulting splittable conjugate fiber, and the texture of the nonwoven fabric obtained from the splittable conjugate fiber.

Examples 3 to 5 and Comparative Examples 3 and 4 A spinneret having polypropylene having a melting point of 135 ° C. and an MI value of 11 g / min as the polymer B and having a cross-sectional shape shown in FIG. 1 (b). (N _A = 3, N _B = 1) and polymer A
The single-hole discharge rate of 0.25 g / min, and the single-hole discharge rate of polymer B is 0.
The same procedure as in Example 1 was carried out except that the unstretched yarn was treated at the draw ratio and the tension heat treatment temperature shown in Table 1 at 23 g / min.

Table 1 shows the dry heat shrinkage ratio and splitting ratio of the obtained splittable conjugate fiber, and the texture of the nonwoven fabric obtained from the splittable conjugate fiber.

[0046]

[Table 1]

As is clear from Table 1, the splittable conjugate fibers obtained in Examples 1 to 5 satisfy the formula and have a high splitting ratio, and the nonwoven fabrics obtained by using these fibers are The splittable conjugate fiber was sufficiently split and had a soft texture.

On the other hand, since the splittable conjugate fibers obtained in Comparative Examples 1 and 4 did not satisfy the formula, they were not sufficiently split by the heat treatment of the calender rolls, and the obtained nonwoven fabrics had a hard texture. there were.

The splittable conjugate fibers obtained in Comparative Examples 2 and 3 had a high splitting rate and were split sufficiently, but S _A was 13
%, The texture of the non-woven fabric obtained by polymer A shrinking too much was hard.

[0050]

EFFECTS OF THE INVENTION The splittable conjugate fiber of the present invention has a large fineness before splitting, so that it is easy to open in the carding process, and is easily split by heat treating it with a calender roll after forming a web. As a result, it becomes possible to provide a non-woven fabric having a soft texture by being made into ultrafine fibers.

[Brief description of drawings]

1 (a), (b) and (c) are cross-sectional views showing an embodiment of a polyester-based splittable conjugate fiber of the present invention.

FIG. 2 is a schematic view showing one embodiment of a state in which the polyester splittable conjugate fiber of FIG. 1 (b) is split.

Claims (1)

[Claims] 1. A splittable conjugate fiber comprising two components, a polyester-based polymer A containing polyalkylene terephthalate as a main component and a thermoplastic polymer B which is incompatible with the polyester-based polymer A. In the cross section of the above, both of the polymers A and B are divided and arranged in a plurality, and the dry heat shrinkage ratio of the polymers A and B satisfies the following formula: . _{(S B - S A) /} (N A + N B) 1/2 ≧ 6 S A ≦ 13 S A: dry heat shrinkage of the polymer A (%), S _B: dry heat shrinkage of the polymer B ( %) N _A : number of divided arrangements of polymer A, N _B : number of divided arrangements of polymer B