JPH09268490A - Polyester-based heat-resistant wet type nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester-based heat-resistant wet type nonwoven fabric excellent in both heat resistance and paper making processability, low in shrinkage percentage after boiling water treatment, capable of maintaining tenacity after being thrown into boiling water. SOLUTION: This nonwoven fabric comprises 90-10wt.% of a polyester fiber and 10-90wt.% of a polyester-based core-sheath conjugate binder fiber consisting of a core part composed of a polyalkylene terephthalate having >=220 deg.C melting point and a sheath part composed of an aromatic polyester and an aliphatic polylactone, having 20-80 deg.C glass transition temperature, 90-130 deg.C crystal starting temperature and 130-180 deg.C melting point and has <=10% shrinkage percentage in boiling water and >=50% tenacity retention after boiling water treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet non-woven fabric which retains its strength even when used in a high temperature atmosphere.

[0002]

2. Description of the Related Art Recently, automobile interior materials, filter materials,
In a fibrous structure of a wet non-woven fabric used as an outer packaging material for tea bags, it is used as a binder such as polyvinyl alcohol and modified acrylic acid polymer, which have been conventionally used for the purpose of adhering constituent fibers (hereinafter referred to as main fibers) to each other. Instead, hot melt binder fibers have become widely used. As the main fiber, the polyester fiber having a relatively low cost and excellent physical properties is most often used, and the binder fiber for adhering this is also often the polyester fiber.

These binder fibers place importance only on the operability at the time of production and the adhesive strength of the non-woven fabric, and have not been studied on the strength at the time of wetting, the contraction at the time of wetting, the texture and the like.

For example, in the case of a non-woven fabric comprising a core-sheath type composite binder fiber whose core part is polyethylene terephthalate (hereinafter referred to as PET) and whose sheath part is a low melting point amorphous polyester copolymerized with an isophthalic acid component, fiber production It has been pointed out that there are few problems with time and that a nonwoven fabric can be formed by a heat treatment at a relatively low temperature, but the strength of the nonwoven fabric becomes weaker in a high temperature atmosphere, and the nonwoven fabric does not have heat resistance. In other words, the heat resistance is not sufficient in the non-woven fabric composed of the binder fiber containing the copolyester having a low crystallinity as the sheath component, and in order to improve this, the research of the binder fiber containing the crystalline copolyester as the sheath component is conducted. Came. However, since this crystalline copolyester has a high crystallization rate, the problem that the crystallization progresses during the thinning during melt spinning to cause yarn breakage, and the crystallinity of the polymer achieves the object of the present application. It does not have sufficient heat resistance because it is not sufficiently high. Further, there is also used a binder fiber having heat resistance by increasing the melting point with a specific amount of the copolymerization of the isophthalic acid component of the core of PET and the sheath part, but the strength is significantly reduced when wet, It is not suitable for practical use due to its high shrinkage ratio.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above problems of a nonwoven fabric composed of binder fibers, has excellent heat resistance and spinnability, has a low shrinkage ratio in boiling water, and is put into boiling water. It is intended to provide a polyester heat-resistant wet non-woven fabric that can retain its strength even afterwards.

[0006]

The present inventors have arrived at the present invention as a result of intensive studies to develop such a novel polyester binder fiber.

That is, the present invention relates to polyester fiber 9
0 to 10% by weight, the core portion is polyalkylene terephthalate having a melting point of 220 ° C. or higher, and the sheath portion has a glass transition temperature of 20 to
80 ° C, crystallization start temperature 90-130 ° C, melting point 130-1
Consisting of 10 to 90% by weight of polyester core-sheath composite binder fiber, which is a block copolymerized polyester composed of aromatic polyester and aliphatic polylactone at 80 ° C., and has a boiling water shrinkage rate of 10% or less and a strong retention after boiling water treatment. The gist of the present invention is a polyester heat-resistant wet non-woven fabric, characterized in that the rate is 50% or more.

90% to 10% by weight of polyester fiber, polyalkylene terephthalate having a core having a melting point of 220 ° C. or higher, a sheath having a glass transition temperature of 20 ° to 80 ° C., a crystal initiation temperature of 90 ° to 130 ° C., and a melting point of 130 ° to 180 ° C. After mixing 10 to 90% by weight of polyester-sheath composite binder fiber, which is a block copolymerized polyester composed of an aromatic polyester and an aliphatic polylactone, and making a paper with a paper machine, [the sheath of the binder fiber is constituted The melting point of the copolyester to (melting point + 30)] ° C. is used to form a nonwoven fabric by fusion heat treatment, and then the crystallization initiation temperature of the copolyester is up to (melting point−20) ° C.
The gist is a method for producing a claimed polyester heat-resistant wet non-woven fabric, which is characterized in that heat treatment for heat resistance is carried out for not less than a minute.

Hereinafter, the present invention will be described in detail. The core of the polyester-sheath composite binder fiber has a melting point of 220 ° C.
It is the above polyalkylene terephthalate. As the polyalkylene terephthalate, polyethylene terephthalate (hereinafter abbreviated as PET), polybutylene terephthalate (hereinafter abbreviated as PBT), and the like are preferable, and a homopolymer thereof or a range not impairing the object of the present invention. If so, 10 mol% of isophthalic acid, phthalic acid, adipic acid, sebacic acid, 1,4-butanediol, diethylene glycol, triethylene glycol, etc.
It may be a copolymer copolymerized to some extent, a matting agent,
You may add additives, such as a lubricant.

The melting point of the core of the polyester-sheath composite binder fiber must be 220 ° C. or higher, preferably 230 ° C. or higher. When it is less than 220 ° C,
When forming a nonwoven fabric, the stability of the heat treatment for fusion is also deteriorated, and the heat treatment causes the core to be thermally deteriorated to lower the strength, which is not preferable.

The sheath portion of the polyester-core-sheath composite binder fiber is a block composed of an aromatic polyester having a glass transition temperature of 20 to 80 ° C., a crystal initiation temperature of 90 to 130 ° C. and a melting point of 130 to 180 ° C. and a fatty acid polylactone. It is a copolyester.

As the aromatic polyester, PET or P
BT and the like are preferable, and as long as they are homopolymers, or within a range that does not impair the object of the present invention, isophthalic acid, phthalic acid, adipic acid, sebacic acid, diethylene glycol, triethylene glycol, etc. can be added in a range of 20 mol% or less. It may be a copolymer obtained by copolymerizing. When it exceeds 20 mol%, the melting point of the copolymer is lowered and it is out of the object of the present invention, which is not preferable.

The aliphatic polylactone has 4 to 4 carbon atoms.
Homopolymers of 11 lactones or copolymers of two or more kinds are preferable, and particularly preferable polylactones include poly ε-caprolactone.

The copolymerization amount of the aliphatic polylactone block-copolymerized with the aromatic polyester is preferably 10 to 20 mol%, more preferably 12 to 18 mol. If the copolymerization amount is less than 10 mol%, the crystallinity will be good, but the melting point will exceed 180 ° C. and high temperature treatment will be required for the fusion heat treatment during nonwoven fabric molding. If it exceeds 20 mol%, the adhesion during spinning will be poor. It is not preferable because it occurs and the thread-forming property deteriorates.

The glass transition temperature (hereinafter abbreviated as Tg) of the copolyester which forms the sheath of the polyester-core-sheath composite binder fiber needs to be in the range of 20 to 80 ° C. The Tg of the copolyester that forms the sheath is 2
If the temperature is lower than 0 ° C, the yarn-forming property deteriorates due to the occurrence of single yarn adhesion during melt-spinning, and it is difficult to manufacture with an ordinary two-component composite melt-spinning apparatus. If it exceeds 80 ° C., it is necessary to raise the stretching temperature during stretching, and since it is high temperature stretching, partial crystallization starts simultaneously with plastic deformation due to stretching, but between the core and the sheath. Since there is a difference in crystallization, there is a problem in that the yarn structure becomes uneven, and thus yarn breakage occurs and drawability decreases.

Crystallization initiation temperature of the copolyester that forms the sheath of the polyester-sheath composite binder fiber (hereinafter, referred to as
It is abbreviated as Tc. ) Needs to be in the range of 90 to 130 ° C. When the Tc of the copolymerized polyester that forms the sheath portion of the polyester-sheath composite binder fiber is less than 90 ° C,
Since crystallization proceeds in the hot drawing step, it is difficult to reconstruct a stable crystal structure in the next heat treatment for heat treatment. If it exceeds 130 ° C, the melting point will be 180 ° C.
It cannot be used as a binder fiber because it will exceed.

The melting point (hereinafter abbreviated as Tm) of the copolymerized polyester which forms the sheath of the polyester-core-sheath composite binder fiber must be in the range of 130 to 180 ° C. The Tm of the copolyester used as the sheath component is 130 ° C.
If it is less than the above range, even if it is made into a fiber, it cannot be used in a high temperature atmosphere or in boiling water because it melts and cannot obtain heat resistance when used in a high temperature atmosphere. Also, 180 ℃
If it exceeds, the heat treatment for fusion at a high temperature is required, the polymer is likely to be decomposed by the high temperature heat treatment, and there is a problem that it is not economically preferable.

In the fibers constituting the wet non-woven fabric of the present invention, 10-9 polyester-sheath composite binder fibers are used.
It is necessary to have 0% by weight. If it is less than 10% by weight, the effect of the binder is insufficient and sufficient adhesive strength between fibers cannot be obtained. Also, 90% by weight
When it exceeds the above value, the heat resistance is excellent, but the handle is hard to the touch and does not have bulk, so that a wet non-woven fabric having a suitable texture cannot be obtained.

The composite ratio of the core portion and the sheath portion of the polyester-based core-sheath composite binder fiber is preferably 2/3 to 3/2, but it is not particularly limited and in order to exert the functions of the two components respectively. It may be selected appropriately.

The main fiber may be selected according to the application,
For example, 6 to 15 denier polyester staple cotton is required if cushioning and bulkiness are required, and 1 to 5 denier polyester staple cotton is preferably used when soft texture is required. A wet non-woven fabric is obtained.

The heat resistant wet non-woven fabric of the present invention has a boiling water shrinkage of 10% or less and a tenacity retention after boiling water treatment of 50% or more. A wet type nonwoven fabric having a boiling water shrinkage ratio of more than 10% has poor dimensional stability in boiling water and is not preferable for the purpose of the present invention. Nonwoven fabrics having a tenacity retention of less than 50% after boiling water treatment are also not preferred for the purpose of the present invention.

The polyester core-sheath composite binder fiber is obtained by melt spinning using a usual core-sheath type composite spinning device, stretching the resulting unstretched fiber, and then crimping it if necessary. be able to. Then, after this fiber is cut into staples, it is mixed with polyester staple which is the main fiber, and paper is made with a paper machine, and [Tm to (Tm + 30) of the copolyester constituting the sheath portion of the binder fiber is produced. ] A non-woven fabric is formed by performing a fusion heat treatment with a heat treatment apparatus heated to a temperature of ° C. That is, the copolymerized polyester in the sheath portion of the polyester-core-sheath composite binder fiber is melted and the fibers are point-bonded to each other to obtain a nonwoven fabric. As a heat treatment device, a hot air circulation dryer,
A rotary drum dryer or the like is used.

The non-woven fabric is formed by the above treatment. In the present invention, the heat treatment for heat resistance of the formed non-woven fabric is further performed at a temperature of [Tc of the sheath portion of the binder fiber to (Tm-20)] ° C. for 2 minutes or more. . By performing this heat treatment for heat resistance, the strength of the nonwoven fabric can be maintained in a high temperature atmosphere and after being put into boiling water.

That is, since the Tm of the core portion is made of polyalkylene terephthalate having a Tm of 220 ° C. or higher, it is necessary to perform hot stretching, but at this time, the sheath portion is also affected by the heat stretching,
Crystallization proceeds. At this time, if the Tc of the block copolyester in the sheath is low, crystallization proceeds, and when the polymer in the core is subjected to heat treatment in a range that does not cause thermal decomposition, the crystal structure formed in the sheath is temporarily collapsed. I can't let you do it. Therefore, such a fiber is inferior in dimensional stability because the sheath restrains the core and the core still has an internal strain. On the other hand, in the present invention, the block copolyester of the sheath has a high Tc as described above, and therefore has relatively low crystallinity during hot stretching. Then, after forming the non-woven fabric, heat treatment for heat resistance is performed [T of the sheath portion of the binder fiber
c- (Tm-20)] [deg.] C. for 2 minutes or more to construct a crystal structure that absorbs new internal strain. Therefore, the dimensional stability is significantly improved.

When the heat treatment time is less than 2 minutes, the treatment time is short and the heat resistance of the nonwoven fabric is insufficient. In addition, since heat resistance does not change even if heat treatment for heat treatment is performed for more than 10 minutes,
It is sufficient to perform the heat treatment for heat treatment in the range of 2 to 10 minutes.

[0026]

[Function] Since the sheath portion of the core-sheath composite binder fiber of the polyester heat-resistant wet non-woven fabric of the present invention is composed of the block copolymerized polyester having crystallinity as described above, adhesion between single fibers and abrasion damage of fibers during melt spinning Nonetheless, the operating condition at the time of manufacturing is good. Furthermore, the wet non-woven fabric of the present invention obtained by mixing at least 10% by weight of the binder fiber is subjected to heat treatment for heat resistance, so that the crystallinity of the block copolymerized polyester in the sheath portion of the core-sheath composite binder fiber is significantly improved. Since it has a thermally stable structure, it is a non-woven fabric with excellent heat resistance.

[0027]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

The various properties described in the examples were measured and evaluated by the following methods.

(1) Relative Viscosity η _R : Measured at a temperature of 20 ° C. in a mixed solvent of equal weight of phenol tetrachloride ethane.

(2) Tg / Tc / Tm: Measured with a differential scanning calorimeter DSC-7 type manufactured by Perkin Elmer at a temperature rising rate of 20 ° C / min.

(3) Nonwoven fabric strength: U manufactured by Orientec Co., Ltd.
Nonwoven fabric width 2.5c using TM 4 type Tensilon
The sample was placed in a thermostatic chamber with m and a length of 15 cm and the temperature conditions could be changed, stretched and cut under the conditions of a pulling speed of 10 cm / min and a gripping interval of 10 cm, and the maximum strength was read. This value was defined as the strength of the nonwoven fabric in a high temperature atmosphere. The temperature of the constant temperature bath was set at two points of 90 ° C. and 110 ° C., and 1 minute after the addition of the constant temperature bath, 10 samples were measured and the average value was obtained. Further, the strength of the nonwoven fabric at room temperature (23 ° C.) was similarly determined at room temperature.

(4) Non-woven fabric tenacity retention rate (%) in a high temperature atmosphere: determined by the following formula. A (%) = (B / C) × 100 In the above formula, A is the strength retention of the nonwoven fabric in a high temperature atmosphere, B is the strength of the nonwoven fabric in a 90 ° C. or 110 ° C. atmosphere (g), and C is heat resistant. Nonwoven fabric strength (g) at room temperature before heat treatment.

(5) Shrinkage rate of boiling water (%): The nonwoven fabric is 2.
Prepare 10 samples each for 5 cm and 2.5 cm width,
After pouring in boiling water (100 ° C.) for 10 minutes, the area of each of 10 samples was measured to obtain an average value, and the boiling water shrinkage rate (%) was determined by the following formula. A (%) = (B−C) × 100 / B In the above formula, A is boiling water shrinkage, B is the area of the non-woven fabric before pouring the boiling water, and C is the area of the non-woven fabric 10 minutes after pouring the boiling water.

(6) Nonwoven fabric tenacity retention (%) after boiling water treatment: UTM 4 type Tensilon manufactured by Orientec Co., Ltd. was used to make the nonwoven fabric 2.5 cm wide and 15 cm long in boiling water (100 ° C.) for 10 minutes. After loading, pulling speed 1
It was stretched and cut under the conditions of 0 cm / min and a gripping interval of 10 cm, and the maximum point strength was read, and this value was taken as the strength of the nonwoven fabric after boiling water treatment. The number of samples was measured 10 each, and the average value was calculated. Further, the strength of the nonwoven fabric at room temperature (23 ° C.) was similarly determined at room temperature. From the obtained value, the strength retention of the nonwoven fabric in boiling water was determined by the following formula. A (%) = (B / C) × 100 In the above formula, A is the non-woven fabric strength retention after boiling water treatment, and B
Is the strength (g) of the nonwoven fabric after boiling water treatment, and C is at room temperature (23
(° C) Nonwoven fabric strength (g).

(7) Texture: The texture of the wet non-woven fabric was evaluated by sensory evaluation in the following three grades. ◯: Good touch and soft feeling. Δ: The touch is slightly hard. X: The feel is hard.

(8) Comprehensive evaluation: ◯: All of the following 5 conditions are satisfied Δ: Four of the following conditions are satisfied ×: Three or less satisfy the following conditions Things [Conditions] 1. It has a strength retention of 50% or more in a high temperature atmosphere (90 ° C.). 2. It has a strength retention of 50% or more in a high temperature atmosphere (110 ° C.). 3. The strength retention after boiling water treatment is 50% or more. 4. The boiling water shrinkage is 10% or less. 5. The texture is good.

Examples 1 to 7 PET pellets having a relative viscosity of 1.38 and 256 ° C. as core components,
Terephthalic acid (TPA) / ethylene glycol (EG) / 1,4-butanediol (1,4-BD) = 100 in the sheath component
/ 50/50 (molar ratio)
Copolyester pellets obtained by copolymerizing caprolactone (ε-CL) or poly δ-valerolactone (δ-VL) according to the ratio shown in Table 1 were dried under reduced pressure. Using the usual two-component composite melt-spinning apparatus, the pellets were spun at a spinning temperature of 270 at a composite ratio of 1: 1 (volume ratio).
Spinning was carried out at a temperature of 120 ° C., a discharge rate of 120 g / min, a number of holes in the die plate of 225, and a spinning speed of 700 m / min. Cold wind the spun yarn (18 ℃)
It was then cooled and taken up to obtain an undrawn yarn. The unstretched filaments obtained were bundled, made into a tow of 100,000 denier, stretched at a draw ratio of 3.3, stretched at a stretching temperature of 60 ° C., subjected to a tension heat treatment at 130 ° C., and after applying an oil agent, no crimp tow. 5 mm
The polyester core-sheath composite binder fibers of Examples 1 to 7 having a single yarn fineness of 2 denier were cut into pieces. Tg / Tc / Tm of the block copolymerized polyester of the sheath component of the obtained polyester-sheath composite binder fibers of Examples 1 to 7
And η _R are shown in Table 1.

Example 8 In Example 3, the core component had a relative viscosity of 1.55 and 227 ° C.
A polyester-based core-sheath composite binder fiber of Example 8 was obtained in the same manner as in Example 3 except that the PBT pellet was used. Table 1 shows Tg / Tc / Tm and η _R of the block copolymerized polyester of the sheath component of the obtained polyester-core / sheath composite binder fiber of Example 8.

[0039]

[Table 1]

The polyester-core-sheath composite binder fibers of Examples 1 to 4 and 6 to 8 had good spinnability. on the other hand,
The polyester-sheath composite binder fiber of Example 5 is
Adhesion occurred during spinning, and the spinnability was poor.

Example 11 Example 3 with a PET fiber having a fineness of 2 denier and a fiber length of 5 mm
The polyester core-sheath composite binder fiber obtained in 1. was mixed at a weight ratio of 1: 1 to prepare a paper using a paper machine, and a fusion heat treatment was performed using a rotary dryer at a heat treatment temperature of 160 ° C. for 100 seconds. The nonwoven fabric strength (g) at room temperature (23 ° C.) of the obtained nonwoven fabric before heat treatment for heat resistance was measured and is shown in Table 2. Next, heat treatment for heat resistance was performed at 100 ° C. for 5 minutes to obtain a heat resistant wet non-woven fabric having a basis weight of 40 g / m ² .

Examples 12 to 13 Heat-resistant wet nonwoven fabrics of Examples 12 to 13 were obtained in the same manner as in Example 11 except that the heat treatment was carried out at the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. It was

Example 14 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 2 was used for the heat treatment temperature and heat treatment temperature shown in Table 2. A heat resistant wet nonwoven fabric of Example 14 was obtained in the same manner as in.

Example 15 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 4 was used for the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A heat resistant wet non-woven fabric of Example 15 was obtained in the same manner as in.

Example 16 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 8 was used at the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A heat resistant wet nonwoven fabric of Example 16 was obtained in the same manner as in.

Example 17 In Example 11, the fineness was 2 denier and the fiber length was 51 mm.
A heat-resistant wet non-woven fabric of Example 17 was obtained in the same manner as in Example 11 except that the PET fiber of Example 1 and the polyester-sheath composite binder fiber obtained in Example 3 were mixed at a weight ratio of 3: 7.

Example 18 In Example 11, the fineness was 2 denier and the fiber length was 51 mm.
A heat-resistant wet non-woven fabric of Example 18 was obtained in the same manner as in Example 11 except that the PET fiber of Example 1 and the polyester-sheath composite binder fiber obtained in Example 3 were mixed at a weight ratio of 7: 3.

Comparative Example 1 Example 11 was repeated except that the polyester-sheath composite binder fiber obtained in Example 5 was used for heat treatment at the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A nonwoven fabric of Comparative Example 1 was obtained in the same manner as in.

Comparative Example 2 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 6 was used at the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A non-woven fabric of Comparative 2 was obtained in the same manner as.

Comparative Example 3 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 7 was used at the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A non-woven fabric of Comparative Example 3 was obtained in the same manner as in.

Comparative Example 4 Example 11 was repeated except that the polyester core-sheath composite binder fiber obtained in Example 1 was used for the heat treatment temperature and heat treatment heat treatment temperature shown in Table 2. A non-woven fabric of Comparative Example 4 was obtained in the same manner as in.

Comparative Example 5 Example 5 was repeated except that the PET fiber having a fineness of 2 denier and a fiber length of 5 mm was mixed with the polyester core-sheath composite binder fiber obtained in Example 3 in a weight ratio of 95: 5. A heat resistant wet nonwoven fabric of Comparative Example 5 was obtained in the same manner as in 11.

Comparative Example 6 Example 6 was repeated except that the PET fiber having a fineness of 2 denier and a fiber length of 5 mm was mixed with the polyester type core-sheath composite binder fiber obtained in Example 3 in a weight ratio of 5:95. A heat resistant wet nonwoven fabric of Comparative Example 6 was obtained in the same manner as in 11.

The physical properties of the nonwoven fabrics obtained in Examples 11 to 18 and Comparative Examples 1 to 6 were measured and evaluated, and the results are shown in Table 2.

[0055]

[Table 2]

In Table 2, the heat-resistant wet-type nonwoven fabric of the present invention has a significantly higher nonwoven fabric strength in a high temperature atmosphere and in boiling water when subjected to heat treatment for heat treatment, and has a low shrinkage ratio in boiling water. And the retention of strength in boiling water were excellent.

In Comparative Examples 1 and 2, T of the sheath portion of the binder fiber was used.
g, Tc, or Tm does not satisfy the constituent requirements of the invention.

The nonwoven fabric of Comparative Example 1 in which the Tm of the sheath portion of the binder fiber was less than 130 ° C. melted in a high temperature atmosphere and was inferior in heat resistance, had a high shrinkage rate in boiling water, and had a dimensional stability in boiling water. Was inferior to

The nonwoven fabric of Comparative Example 2 in which the Tc of the sheath portion of the binder fiber exceeds 130 ° C. and the Tm of the binder fiber exceeds 180 ° C., the polymer is decomposed by the heat treatment for fusion during molding of the nonwoven fabric and the strength of the nonwoven fabric is poor. Met.

In the non-woven fabric of Comparative Example 3 in which the Tc of the sheath portion of the binder fiber was less than 90 ° C., crystallization proceeded in the heat drawing step and a stable crystal structure was not reconstructed in the next heat treatment for heat treatment, The strength of the non-woven fabric in a high temperature atmosphere was poor.

The nonwoven fabric of Comparative Example 4 in which the Tm of the sheath portion of the binder fiber exceeded 180 ° C. was inferior in nonwoven fabric strength due to decomposition of the polymer due to heat treatment for fusion during molding of the nonwoven fabric.

In Comparative Examples 5 to 6, the composition ratio of the polyester-sheath composite binder fiber to the main fiber was 1: 9 to 9 :.
It deviates from 1.

The non-woven fabric of Comparative Example 5 in which the polyester-core-sheath composite binder fiber was less than the composition ratio of the present invention, the adhesion between the fibers was insufficient and, as a result, the non-woven fabric was poor in strength and heat resistance. Met.

The non-woven fabric obtained in Comparative Example 6 in which the polyester-core-sheath composite binder fiber is larger than the composition ratio of the present invention is excellent in heat resistance and non-woven fabric strength, but is hard to the touch and bulky and paper-like. It was a thing.

[0065]

EFFECTS OF THE INVENTION The polyester-core-sheath composite binder fiber of the present invention does not cause adhesion between fibers during spinning during fiber production. In addition, the wet non-woven fabric obtained by using this fiber has a strong texture even under a high temperature atmosphere and in boiling water and has a heat resistance and a soft texture.

Claims (2)

[Claims] 1. 90 to 10% by weight of polyester fiber,
A block composed of an aromatic polyester and an aliphatic polylactone, the core of which is a polyalkylene terephthalate having a melting point of 220 ° C. or higher, and the sheath of which has a glass transition temperature of 20 to 80 ° C., a crystallization starting temperature of 90 to 130 ° C., and a melting point of 130 to 180 ° C. A polyester-based heat-resistant material, comprising 10 to 90% by weight of a polyester-sheath composite binder fiber which is a copolyester, and having a boiling water shrinkage of 10% or less and a strength retention after boiling water treatment of 50% or more. Wet non-woven fabric. 2. 90 to 10% by weight of polyester fiber,
A block composed of an aromatic polyester and an aliphatic polylactone, the core of which is a polyalkylene terephthalate having a melting point of 220 ° C. or higher, and the sheath of which has a glass transition temperature of 20 to 80 ° C., a crystallization starting temperature of 90 to 130 ° C., and a melting point of 130 to 180 ° C. After mixing 10 to 90% by weight of polyester-core-sheath composite binder fiber which is a copolyester, and making a paper by a paper machine, [melting point of copolyester constituting the sheath of binder fiber to (melting point +30)] A fusion heat treatment is performed at a temperature of [deg.] C to form a nonwoven fabric, and then a heat treatment for heat treatment is performed at a temperature of [crystallization start temperature of the copolymerized polyester to (melting point -20)] [deg.] C for 2 minutes or more. A method for producing a polyester heat resistant wet non-woven fabric.