JPH05279922A - Conjugate binder fiber having shape memorizing ability - Google Patents

Abstract

PURPOSE:To obtain a conjugate fiber binder, having the shape memorizing ability and capable of providing a nonwoven fabric or hard cotton returning to the shaped form by light heating even if the shape is lost by fusing and shaping the binder fiber. CONSTITUTION:A polyester, prepared by copolymerizing a >=6C long-chain aliphatic dicarboxylic acid and having <=37 deg.C glass transition point and >=150 deg.C melting point and a polyolefinic polymer having a lower melting point than that of the polyester by >=20 deg.C are respectively arranged in the core and sheath to carry out the conjugate spinning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binder fiber having a shape-memory ability, and more particularly to a binder fiber having a shape-memory ability which can be used as a soft sanitary material having a good fit property.

[0002]

2. Description of the Related Art In non-woven fabrics and the like, the main fiber is
It is well known that a binder fiber made of a polymer having a lower melting point than that of the fiber or a binder fiber spun with a low melting point polymer is mixed to maintain the shape. As the binder component, a polyester-based polymer, an olefin polymer, or the like suitable for the application is selected and used.

In recent years, synthetic polymers having a shape memory ability have been developed and marketed. This polymer has a large elasticity change before and after the glass transition point, and its function is, for example, that it is first formed into an arbitrary shape "A" and then the shape "A" is changed.
In this state, heating is performed to crystallize (entanglement of crystal parts) or intermolecular crosslinks to generate fixed points to memorize the shape. Then, an external force is applied in an atmosphere having a glass transition temperature or higher and lower than the above heating temperature to deform into a shape “B”, and the shape can be changed to a shape “B” by cooling the glass transition temperature to a temperature below the glass transition point. It has a function of recovering the shape of "A" by heating above, that is, a "shape memory ability".

As a resin material having a shape memory ability, a polytransisoprene resin (JP-A-55-93806) is used.
No.), polynorbornene-based resin (JP-A-59-5352).
No. 8), a mixture of a vinyl resin and an acrylic acid resin or a synthetic rubber (JP-A-63-17952).
No.) etc. are known. Further, a polyurethane type shape memory polymer yarn (Japanese Patent Laid-Open No. 2-16713) is disclosed.

However, in the conventionally known resin material,
It was difficult to efficiently produce a composite binder fiber having a denier of 6 or less and used for a non-woven fabric or the like because of poor spinnability.
Further, it has been proposed to compress and deform a bulky non-woven fabric or the like for transportation or storage from the need of cost reduction, but conventionally, for example, a non-woven fabric using a polyethylene terephthalate / polyethylene composite binder fiber may have wrinkles,
There was a problem that it was not restored to its original shape.

[0006]

The present invention is intended to solve such problems. That is, the present invention provides a composite binder fiber which can be a non-woven fabric having good bulk recovery when a temperature near body temperature is applied.

[0007]

The present inventor has arrived at the present invention as a result of extensive studies to solve the above problems. That is, the first invention of the present application is a composite binder fiber composed of a copolyester having a shape-memory ability with a glass transition point of 37 ° C. or lower and a melting point of 150 ° C. or higher and a polymer having a melting point of 20 ° C. or lower than the copolyester. In the second invention of the present application, the copolyester of the first invention has 6 carbon atoms.
A gist of the composite binder fiber is polyethylene terephthalate obtained by copolymerizing the above long-chain aliphatic dicarboxylic acid.

The present invention will be described in detail below. The copolyester having shape memory ability used in the present invention has the following properties.

After the melt molding, the shape is memorized by crystallization in a heating atmosphere. When an external force is applied in a temperature range that is higher than the glass transition point and lower than the temperature at which the shape is memorized, it deforms relatively easily. When the temperature is kept below the glass transition point while maintaining the deformed shape, the deformed shape is fixed. When an external force is not applied to this and the temperature is higher than the glass transition point, the shape remembered is restored.

The glass transition point of the copolyester must be 37 ° C. or lower. If the glass transition temperature exceeds 37 ° C,
It is not suitable because the shape cannot be recovered to a bulky nonwoven fabric near the human body temperature, for example.

The melting point of the copolyester must be 150 ° C. or higher. If the melting point is less than 150 ° C, the melting point of the polymer used as the binder component when used as binder fiber must be 130 ° C or less, and the heating temperature range for imparting shape memory becomes narrow, resulting in production efficiency. It becomes bad and not practical.

Next, as a method of obtaining a copolyester having a shape memory ability, a method of copolymerizing an aromatic polyester segment (hard segment) and an aliphatic polyester segment (soft segment) at an appropriate ratio to obtain a polymer Another example is a method of copolymerizing an aromatic polyester segment (hard segment) and a polyalkylene glycol segment (soft segment) at an appropriate ratio to obtain a polymer, but the former is preferable.

The aromatic polyester segment means a polyester segment having at least one aromatic ring in the repeating unit of polyester, and the aliphatic polyester segment means a polyester segment in which the repeating unit of polyester is an aliphatic compound. ..

As the aromatic monomer component constituting the hard segment, for example, terephthalic acid, isophthalic acid,
Examples thereof include dicarboxylic acids such as bisphenol A and p-oxybenzoic acid, diols and hydroxycarboxylic acids.

Examples of the aliphatic monomer component which constitutes the hard segment with the aromatic monomer or the soft segment itself includes, for example, adipic acid,
Azelaic acid, dodecanedioic acid, eicosanedioic acid, ethylene glycol, butanediol, hexanediol, ε
-Dicarboxylic acids such as caprolactone, diols and oxycarboxylic acids (or lactones). Polyalkylene glycols such as polyethylene glycol and polytetramethylene glycol can also function as the soft segment component.

As the hard segment, polyester of ethylene terephthalate unit or butylene terephthalate unit is preferable, but ethylene terephthalate unit is most preferable in view of economy and physical properties. The soft segment is preferably a long-chain aliphatic dicarboxylic acid such as azelaic acid, sebacic acid, dodecanedioic acid, etc., and particularly an ester unit of an aliphatic dicarboxylic acid having 6 or more carbon atoms and ethylene glycol.

In the copolyester used in the present invention, it is considered that the soft segment acts as an intramolecular plasticizer to accelerate the crystallization of the polymer and cause the entanglement of the crystallized portions to give a fixed point. .. Even a copolyester composed of only these hard and soft segments can be made into a polyester having sufficient shape memory ability, but even if a molecular structure capable of intermolecular crosslinking is introduced, the rubber will retain its shape by vulcanization. Similar to the principle described above, it can function as a fixing point for fixing the shape to be memorized by cross-linking the polyester molecules at necessary points.

Specific examples of the molecular structure capable of intermolecular crosslinking include a structure in which a monomer component having an unsaturated bond is copolymerized to introduce an unsaturated bond into the main chain of polyester. Intermolecular cross-linking becomes possible by cleaving by a suitable means when the shape of this unsaturated bond is fixedly stored. As a monomer component having an unsaturated bond that can be copolymerized with polyester, for example, maleic anhydride, maleic acid, chloromaleic acid, itaconic acid, fumaric acid,
Citraconic acid, hettic acid, hettic anhydride, 2-butene-
Examples thereof include unsaturated dicarboxylic acids such as 1,4-diol and 3-butene-1,2-diol or unsaturated diols.

It is also an effective means to copolymerize a polyester with a trifunctional or higher functional monomer component. In this case, when the shape is fixed and stored, intermolecular crosslinking can be performed by adding and reacting a crosslinking agent having a hydroxyl group or a carboxyl group of polyester, an isocyanate group, an amino group or the like. The polyester in the present invention may be copolymerized with other auxiliary raw materials, and may contain various additives and the like, if necessary, as long as the objects of the present invention are not impaired. ..

The constituent components of the monomers constituting the copolyester used in the present invention and the copolymerization ratio thereof can be selected within a wide range, but in consideration of economical efficiency, versatility, physical properties and the like,
For example, the following are preferable. That is, terephthalic acid as a dicarboxylic acid is 50 to 95 mol%, preferably 6
It is a polyester in which 0 to 90 mol%, dodecanedioic acid is 5 to 50 mol%, preferably 10 to 40 mol%, and ethylene glycol is used as a diol in a ratio of 100 mol%. In this example, the repeating unit consisting of ethylene glycol and terephthalic acid is a hard segment,
Repeating units consisting of ethylene glycol and dodecanedioic acid share the function of soft segment.

The binder fiber of the present invention is a composite fiber in which the above-mentioned copolyester having a shape memory capacity and a polymer as a binder component having a melting point lower by 20 ° C. or more than that are combined in a core-sheath shape or a side-by-side shape. .. As the binder component of the composite binder fiber of the present invention, polyethylene terephthalate is copolymerized with a third component such as isophthalic acid, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, low density polyethylene (LDPE). , Linear low density polyethylene (LLDPE), high density polyethylene (HDPE), polypropylene, copolymers of ethylene and propylene, modified polyethylene obtained by copolymerizing ethylene or propylene with unsaturated carboxylic acid such as acrylic acid, modified polypropylene, etc. Examples of the polyolefin polymer, polyamide polymer such as nylon 612, and the like.

When a polyolefin-based polymer is used as a binder component, a more preferable product can be obtained especially for applications requiring softness. The shape of the composite fiber is not limited to a round cross section, and may be a modified cross section such as a hollow cross section or a triangular cross section.

The composite binder fiber having a shape memory capacity of the present invention can be used alone as a product having a shape memory capacity such as a nonwoven fabric having a shape memory capacity. Also,
Used in combination with fibers consisting of the polymer itself having shape memory ability, or mixed with synthetic fibers such as polyester and nylon, semi-synthetic fibers such as acetate, natural fibers such as cotton, etc. at a ratio according to the purpose of use. Even so, it can be a product having a shape memory ability.

When the shape is memorized in the process of heat treatment using the binder fiber having a shape-memory ability of the present invention such that a fixed point is generated, when the temperature reaches a temperature near the glass transition point, the original shape is retained. The action that tries to return to will work and it will be possible to recover the original shape.

[0025]

[Function] As in the present invention, a composite binder fiber is prepared by composite spinning a copolyester having a glass transition point of 37 ° C or lower and a melting point of 150 ° C or higher and a shape memory ability and a polymer having a melting point of 20 ° C or lower than the copolyester. Then, a non-woven fabric having shape retention can be obtained by using the composite binder fiber alone or in combination with a fiber composed of the polymer itself having a shape memory capability, and the glass transition point of the copolyester having a shape memory capability is 37 If heat-treated at a temperature of not less than 0 ° C. and not more than the melting point, the original shape can be easily recovered at a temperature not lower than the glass transition point of the copolyester having shape memory ability even if the shape is changed. A shape-memory copolyester is polyethylene terephthalate obtained by copolymerizing a long-chain aliphatic dicarboxylic acid having 6 or more carbon atoms, and has a melting point higher than that of the copolymerized polyethylene terephthalate.
When the composite is spun with a polymer having a temperature lower than 20 ° C. to form a composite binder fiber, a non-woven fabric having more excellent shape recovery ability can be obtained.

[0026]

EXAMPLES The present invention will now be described with reference to examples. In addition, the characteristic value of the polyester of an Example is measured as follows. (1) Intrinsic Viscosity An equal weight mixture of phenol and ethane tetrachloride was used as a solvent and measured at a temperature of 20 ° C. (2) Melting point and glass transition point Differential scanning calorimeter (manufactured by Perkin Elmer, DSC-2
Type) was used, and the temperature was raised at a rate of 20 ° C./min.

Example 1 45 kg of bis (β-hydroxyethyl terephthalate) obtained by the esterification reaction of terephthalic acid and ethylene glycol and its oligomer were added to 9.3 k of dodecanedioic acid.
g, 0.4 kg of maleic acid, 9.0 kg of ethylene glycol, and 26 g of tetrabutyl titanate as a catalyst, 250
The esterification reaction was carried out for 2 hours at ℃ under nitrogen gas pressure of 3.2 kg / cm ² . The copolymerization amount of dodecanedioic acid was 16 mol% and the copolymerization amount of maleic acid was 1.5 mol%. Transfer the resulting esterification product to a polycondensation reactor at 280 ° C and 0.2 torr for 3 hours.
A time polycondensation reaction was performed to obtain a copolyester A. The obtained copolyester A has a glass transition point of 35 ° C. and a melting point of 218.
The intrinsic viscosity was 0.65 at ℃.

The copolyester A obtained was used as a core, and the melting point was 1
Using a melt spinning device with high-density polyethylene at 30 ℃ in the sheath, pass it through a spinneret with 415 spin holes, and
Melt spinning was performed at 70 ° C., the discharge rate of the core portion was 180 g / min, and the discharge rate of the sheath portion was 120 g / min. After cooling the spun fiber yarn, the take-up speed is 1000m
/ min to obtain an undrawn fiber yarn. The obtained yarns were bundled into a tow of 100,000 denier, and the draw ratio was 3.1,
The film was drawn at a drawing temperature of 60 ° C., heat-treated with a heat drum at 115 ° C., and then crimped using a push-type crimper. Then, cut it to a length of 51 mm and fineness of single yarn 2 denier,
A composite binder fiber having a single fiber strength of 3.4 g / denier and a shape memory capacity of 80% elongation was obtained.

This fiber was passed through a card machine to give a basis weight of 50 g / m ²
The resulting web was heat-treated for 5 minutes using a heat dryer at a temperature of 140 ° C. to obtain a nonwoven fabric having a thickness L of 1.1 cm. This non-woven fabric had a very soft feel.

A load was placed on the obtained non-woven fabric to be compressed to a thickness of 0.2 cm, treated as it was in a heat dryer at a temperature of 70 ° C. for 30 minutes, taken out, and cooled at room temperature for 30 minutes, and then the load was removed. ..
After a further 30 minutes, the thickness M was measured and found to be 0.22 cm, which was fixed by compression. This compressed and fixed nonwoven fabric is treated with a heat dryer at a temperature of 70 ° C for 30 minutes without applying a load, and then taken out,
After cooling at room temperature for 30 minutes, the thickness N was measured and found to be 1.0 cm, and the initial shape was recovered. Also, the feel of the non-woven fabric was very soft as at the beginning.

Example 2 and Comparative Example 1 Same as Example 1 except that maleic acid was not added and the copolymerization amount of dodecanedioic acid was changed to 18 mol% and 40 mol% in Example 1. And the composite binder fibers B and C
Got The physical properties of these copolyester fibers are shown in Table 1. Further, in Example 1, these copolyesters B and C were used in place of the copolyester A, the heat drum temperature in the stretching step was changed to 115 ° C and 100 ° C, and a heat dryer treatment for forming a nonwoven fabric was performed. Change the temperature 160
Nonwoven fabrics of Example 2 and Comparative Example 1 were obtained in the same manner as in Example 1 except that the temperature was 120 ° C and 120 ° C.

The shape memory performance is the same as that of the first embodiment.
The thickness L, N and M were measured and evaluated. The results are also shown in Table 1.

[0033]

[Table 1]

In the same manner as in Example 1, Example 2 is compressed and fixed when treated at a temperature above the glass transition point under compression,
When heat-treated under no load, the original thickness was restored, and shape memory performance could be confirmed. However, in the case of Comparative Example 1 which is a copolyester fiber having a large copolymerization amount of dodecanedioic acid, compression fixability,
The shape recoverability was poor.

[0035]

According to the invention, a composite binder fiber having a shape memory ability can be obtained. The non-woven fabric prepared using this, once the pattern is lost,
Light heating returns to the original patterned state. In addition, since the glass transition point of copolyester with shape memory ability is set near body temperature, even if it is in a state where the bulk is reduced during transportation and packaging, it is soft and bulky when worn by the human body, such as a disposable diaper or napkin. Sanitary materials can be obtained.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

In recent years, synthetic polymers having a shape memory ability have been developed and marketed. This polymer has a large elasticity change around the glass transition point, and its function is
For example, it is first shaped into an arbitrary shape “A” and then heated in that state “A” to crystallize (entanglement of crystal parts).
Alternatively, the shape is memorized by generating fixed points by intermolecular crosslinking. Next, an external force is applied in an atmosphere having a glass transition temperature or higher and lower than the above heating temperature to be deformed into the shape “B”,
If it is cooled to below the glass transition point as it is, it can have a shape "B", and it has the function of recovering to the shape of "A" by heating above the glass transition point without applying external force again, that is, it has a "shape memory ability". is there.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

A load was placed on the obtained non-woven fabric to be compressed to a thickness of 0.2 cm, treated in a heat drier at a temperature of 37 ° C. for 30 minutes, taken out, cooled at room temperature for 30 minutes, and then removed from the load. ..
After a further 30 minutes, the thickness M was measured and found to be 0.22 cm, which was fixed by compression. This compression-fixed non-woven fabric is treated with a heat dryer at a temperature of 37 ° C for 30 minutes without any load, and then taken out,
After cooling at room temperature for 30 minutes, the thickness N was measured and found to be 1.0 cm, and the initial shape was recovered. Also, the feel of the non-woven fabric was very soft as at the beginning.

Claims (2)

[Claims] 1. A glass transition point of 37 ° C. or lower and a melting point of 150 ° C.
A composite binder fiber comprising a copolyester having the above shape memory ability and a polymer having a melting point lower than that of the copolyester by 20 ° C. or more. 2. The composite binder fiber according to claim 1, wherein the copolyester is polyethylene terephthalate obtained by copolymerizing a long-chain aliphatic dicarboxylic acid having 6 or more carbon atoms.