JPH09324323A - Heat-bondable conjugate polyester fiber having low shrinkage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat-bondable conjugate polyester fiber having low heat shrinkage and high dimensional stability and giving a fiber structure such as a non-woven fabric resistant to deformation caused by the lowering of the bonding strength even by using the fabric in a hot atmosphere. SOLUTION: This heat-bondable conjugated fiber is composed of a core consisting of a polyalkylene terephthalate having a melting point of >=220 deg.C and a sheath consisting of a copolymerized polyester having a glass transition point of 20-80 deg.C, a crystallization starting temperature of 90-130 deg.C and a melting point of 130-180 deg.C and composed or an aromatic polyester and an aliphatic polylactone. The dry-heat shrinkage of the yarn is <=3% at 100 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester-based low shrinkage heat-bonding composite fiber suitable for bonding a fiber structure such as a nonwoven fabric.

[0002]

2. Description of the Related Art Heretofore, as a polyester heat-bonding composite fiber, a fiber having polyethylene terephthalate as a core component and a polyethylene terephthalate copolymer obtained by copolymerizing an isophthalic acid component as a sheath component has been widely used.

However, the copolymerized polyester as the sheath component of the composite fiber is amorphous and does not show a clear crystal melting point, and softening begins when the glass transition temperature is exceeded. For this reason, it cannot be heat-set during the production of the fiber, and the fiber shrinks during the heat-bonding process. Then, there is a problem that the adhesive strength is lowered and the adhesive is deformed.

As a solution to such a problem, Japanese Unexamined Patent Publication (Kokai) No. 7-119010 discloses that a core component is made of polyalkylene terephthalate having a melting point of 220 ° C. or higher, a sheath component is made of aromatic polyester and an aliphatic polylactone, and glass is used. Transition point
20 ~ 80 ℃, Crystal start temperature 90 ~ 130 ℃, Melting point 130 ~ 180 ℃
The core-sheath type heat-bonded composite fiber using the copolyester is disclosed.

However, since the heat-bonding composite fiber disclosed in this publication does not have a sufficiently low heat shrinkage ratio, a nonwoven fabric using this fiber has a poor dimensional stability due to shrinkage of the nonwoven fabric during heat-bonding treatment, or high temperature. There was a problem of shrinkage during use in an atmosphere.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a fibrous structure such as a non-woven fabric which has a small heat shrinkage ratio, good dimensional stability, and does not deform due to a decrease in adhesive strength even when used in a high temperature atmosphere. It is intended to provide a polyester-based low shrinkage heat-bonding composite fiber capable of obtaining a body.

[0007]

Means for Solving the Problems The present invention is intended to solve the above problems, and its gist is to use a polyalkylene terephthalate having a melting point of 220 ° C. or more as a core component and an aromatic polyester and an aliphatic polylactone as a sheath component. , Glass transition point 20 ~ 80 ℃, crystal start temperature 90 ~ 130 ℃, melting point 130 ~ 180
A core-sheath composite fiber using a copolyester having a temperature of 100 ° C., which is a polyester-based low shrinkage heat-bonding composite fiber characterized by having a dry heat shrinkage ratio at 100 ° C. of 3% or less.

The present invention will be described in detail below. First, in the composite fiber of the present invention, the core component has a melting point of 220
It is necessary to use polyalkylene terephthalate at a temperature of not less than ° C. When the melting point of the core component polyester is less than 220 ° C., it is difficult to stably form the conjugate fiber, and the stability at the time of heat-bonding treatment is deteriorated. As specific examples of polyalkylene terephthalate, polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are preferable, and a small amount of a copolymerization component, a matting agent, an additive such as a lubricant is contained as long as the characteristics are not impaired. You may have.

On the other hand, the sheath component is composed of aromatic polyester and aliphatic polylactone and has a glass transition point of 20-80.
A copolyester having a crystallization temperature of 90 to 130 ° C. and a melting point of 130 to 180 ° C. is used.

As the aromatic polyester constituting the copolyester, polyalkylene terephthalate, specifically, PET and / or PBT is preferable, and isophthalic acid, phthalic acid, adipic acid, sebacine are used as long as the characteristics thereof are not impaired. It may contain a copolymerization component such as an acid, 1,4-butanediol, diethylene glycol or triethylene glycol.

On the other hand, as the aliphatic polylactone, there are homopolymers or copolymers of lactones having 4 to 11 carbon atoms,
A particularly good polylactone is poly ε-caprolactone.

The copolymerization ratio of the aromatic polyester and the aliphatic polylactone is preferably 90/10 to 80/20 in terms of molar ratio. If the proportion of the aliphatic polylactone is lower than this, the crystallinity will be better, but the melting point will be 180 ° C or higher, and high-temperature treatment will be required during heat treatment, while if it is higher than this, single yarn adhesion will occur during spinning, resulting in spinning. The sex becomes worse.

The copolymerized polyester as the sheath component has a glass transition point (Tg) of 20 to 80 ° C. and a crystal initiation temperature (Tc) of 90 to
It is necessary to keep the melting point (Tm) at 130 ° C within the range of 130 to 180 ° C.

When the Tg of the copolyester is less than 20 ° C., single yarn adhesion occurs during melt spinning, resulting in poor spinnability, and ordinary two-component composite melt spinning cannot be used. If the Tc of the copolyester is less than 90 ° C, it becomes difficult to obtain suitable crystallinity, and if it exceeds 130 ° C, the Tm
Is over 180 ℃ and cannot be used as a heat-bonded fiber. Further, if the Tm of the copolyester is less than 130 ° C., even if it is made into fibers, heat resistance cannot be obtained when used in a high temperature atmosphere. On the other hand, when Tm exceeds 180 ° C., a high temperature heat-bonding treatment is required, which is not economically preferable and heat treatment tends to cause decomposition of the polymer.

Further, the heat-bonded composite fiber of the present invention needs to have a dry heat shrinkage at 100 ° C. of 3% or less. When the dry heat shrinkage ratio exceeds 3%, particularly when the heat-bonding composite fiber is used in a high proportion, the fiber structure shrinks during the heat-bonding treatment, resulting in poor dimensional stability.

In order to obtain a heat-bonding composite fiber having a dry heat shrinkage of 3% or less, oriented crystal is formed in the drawing step and then a temperature lower than the crystal melting point of the copolyester of the sheath component (heat-bonding component), for example, 100. Tension rate using a heat drum at ~ 130 ° C
A fixed length or tension heat treatment of 1.00 to 1.03 times may be performed. This is possible only when the copolyester of the sheath component shows a clear crystalline melting point, and softening starts at Tg or higher as in the conventional heat-bonded composite fiber using the amorphous copolyester as the sheath component. It was impossible with such a thing.

The heat-bonded conjugate fiber of the present invention is prepared by spinning the core-sheath type conjugate fiber by a conventional method using the polyester for the core component and the sheath component as described above and drawing it at a speed of 500 to 1200 m / min. After orientation and crystallization by stretching at 100 ° C. to 130 ° C., a fixed length or tension heat treatment of 1.00 to 1.03 times is applied using a heat drum at 100 to 130 ° C., and crimping is applied if desired, and then stapled. Can be obtained. In addition, it is preferable to add mechanical crimping because good mixing and opening properties can be obtained.

The heat-bonded conjugate fiber of the present invention is suitable for nonwoven fabrics. Although the non-woven fabric can be formed by using only the heat-bonded composite fiber, it is usually used in combination with another fiber having a higher melting point than the melting point of the sheath component of the heat-bonded composite fiber. When used in combination with another fiber, it is desirable that the proportion of the heat-bonded composite fiber be 5% by weight or more.

Other fibers include synthetic fibers such as polyester fibers, nylon fibers, acrylic fibers and polypropylene fibers, chemical fibers such as rayon fibers and acetate fibers,
Examples include natural fibers such as wool, cotton and hemp.

Among them, polyester fibers such as PE
Fibers made of T, PBT, polyethylene-2,6-naphthalate, and polyesters containing these as the main components and containing a copolymerization component such as isophthalic acid, 5-sodium sulfoisophthalic acid, and diethylene glycol are preferred. Also,
The cross-sectional shape of the polyester fiber may be a round cross section or a modified cross section, and may be hollow or non-hollow. Further, the fineness is not particularly limited, and may be determined according to the required characteristics depending on the application, but generally 2 to
A 20 denier one is used. The crimp form is also not particularly limited, but when a non-woven fabric is used as a cushion material, one having a conjugate type three-dimensional crimp is preferable because a good cushioning property can be obtained. The polyester fiber may be provided with an ordinary padding oil agent or may be provided with a silicone type or non-silicone type slippery oil agent.

[0021]

The heat-bonding conjugate fiber of the present invention uses a specific crystalline copolyester as a heat-bonding component (sheath component) and has a small dry heat shrinkage, so that the heat shrinkage is small and the dimensional stability is high. Is good. Also, the heat-adhesive component has a melting point
Since it is a copolyester having a temperature of 100 ° C. or higher, a non-woven fabric or the like using the same is not likely to be deformed even in a high temperature atmosphere of about 70 to 80 ° C. and is hard to set.

[0022]

Next, the present invention will be described specifically with reference to examples. The methods for evaluating various physical properties described in the examples are as follows. (1) Intrinsic viscosity ([η]) Using an equal weight mixture of phenol and ethane tetrachloride as a solvent,
It was measured at a sample concentration of 0.5 g / dl and a temperature of 20 ° C. (2) Tg, Tc, and Tm A differential scanning calorimeter DSC-7 type manufactured by Perkin Elmer was used, and measurement was performed at a temperature rising rate of 20 ° C./min. (3) Dry heat shrinkage It was measured with a load of 50 mg / d by the method of JISL-1015-7-15. (4) Place the heat-formed non-woven fabric with a thermal deformation degree of 30 cm x 30 cm in the center of a square formwork with a horizontally placed inscribed circle of 20 cm in diameter, and place a 200 g weight on the center of the non-woven fabric. And allowed to stand in an atmosphere of 110 ° C. for 60 minutes. Then, after cooling to room temperature and removing the weight, the degree of sagging of the central part of the nonwoven fabric with respect to the original shape was measured. (The smaller the number is, the more difficult it is to deform.) (5) Nonwoven fabric strength Using UTM-4 type Tensilon manufactured by Orientec,
A non-woven fabric with a width of 2.5 cm and a length of 15 cm is produced and the pulling speed is 10 cm /
The sheet was stretched and cut under the condition that the grip interval was 10 cm, and the maximum strength was read.

Examples 1 to 7 and Comparative Examples 1 to 5 [η] 0.67 as a core component, PET having a Tm of 256 ° C., a copolymer having a molar ratio of PET and PBT of 50/50 as a sheath component, and poly-ε-. Copolyester obtained by copolymerizing caprolactone (PCL) or poly-δ-valerolactone (PVL) in the ratio shown in Table 1 was used, and each pellet was dried under reduced pressure and then supplied to a normal core-sheath composite melt spinning device. However, with a composite ratio (volume ratio) of 1/1, spinning temperature 270 ° C, discharge rate 206g
/ Min, the number of spinning holes was 225, and the spinning speed was 700 m / min. The spun yarn was cooled with cold air at 18 ° C. and taken out to obtain an undrawn yarn. The unstretched yarn obtained was bundled, made into a tow of 100,000 d, stretched at a draw ratio of 3.3 times, and stretched at a drawing temperature of 60 ° C., and subjected to a tension heat treatment with a heat drum at a temperature shown in Table 1 and a tension ratio of 1.01 times. Was applied, crimped by a push-in crimper, and then cut into a length of 51 mm to obtain a heat-bonded composite fiber having a single fiber fineness of 4 d. The obtained heat-bonded composite fiber and single fiber fineness 2
d, PET fiber having a length of 51 mm was mixed at a weight ratio of 50/50, made into a web with a card machine, and then heat-bonded at a temperature shown in Table 1 using a rotary dryer to give a basis weight of 40 g / m 2. ^Two non-woven fabrics were obtained. Table 1 shows the dry heat shrinkage ratio of the heat-bonded composite fiber, the thermal deformation degree of the nonwoven fabric, and the tenacity.

[0024]

[Table 1]

In each of Examples 1 to 7, a heat-bonding composite fiber having good spinnability and a small dry heat shrinkage was obtained, and a nonwoven fabric using this was one having a high strength and a small thermal deformation degree. there were.

On the other hand, Comparative Examples 1 to 5 had the following problems. In Comparative Example 1, the sheath component has a Tm of 180.
Since the temperature was higher than 0 ° C, the polymer was decomposed by heat bonding during the formation of the nonwoven fabric, and the thermal deformation of the nonwoven fabric was also large. In Comparative Example 2, since the sheath component has a low Tm, the spinnability is poor and the tension heat treatment temperature cannot be increased.
The degree of thermal deformation of the non-woven fabric was large. In Comparative Example 3, since the Tc of the sheath component exceeds 130 ° C. and the Tm of the sheath component exceeds 180 ° C., decomposition of the polymer occurs due to heat adhesion during molding of the nonwoven fabric,
The degree of thermal deformation of the non-woven fabric was also large. In Comparative Example 4, since the sheath component had a low Tc, the degree of thermal deformation of the nonwoven fabric was large. In Comparative Example 5, since the tension heat treatment temperature was low and the dry heat shrinkage rate was large, the nonwoven fabric shrank due to heat adhesion during the molding of the nonwoven fabric so that the dimensional stability was poor and the thermal deformation degree of the nonwoven fabric was large.

[0027]

According to the present invention, there is provided a fibrous structure such as a non-woven fabric which has a small heat shrinkage ratio, good dimensional stability, and does not deform even if used in a high temperature atmosphere and has a reduced adhesive strength. A polyester-based low shrinkage heat-bonding composite fiber that can be obtained is provided.

Claims (1)

[Claims] 1. A core component composed of polyalkylene terephthalate having a melting point of 220 ° C. or higher, a sheath component composed of an aromatic polyester and an aliphatic polylactone, having a glass transition point of 20 to 80 ° C., a crystal starting temperature of 90 to 130 ° C., and a melting point of 130 to A polyester-based low shrinkage heat-bonding composite fiber, which is a core-sheath composite fiber using a copolyester having a temperature of 180 ° C. and a dry heat shrinkage ratio at 100 ° C. of 3% or less.