JP3383471B2 - Thermal adhesive composite fiber - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-adhesive conjugate fiber capable of providing a nonwoven fabric having an excellent feeling at a high processing speed, and particularly to a nonwoven fabric suitable for sanitary materials. The present invention relates to a heat-bondable conjugate fiber that can be used.

[0002]

2. Description of the Related Art Conventionally, there has been widely known a technique for producing a non-woven fabric by using a thermo-adhesive conjugate fiber in which high molecular polymers having different melting points are combined, and a disposable type diaper or a sanitary napkin is used. Firstly, it is used as a constituent material for various sanitary materials. For example, Japanese Patent Publication Sho 55-
No. 483, Japanese Patent Publication No. 3-47325, and Japanese Patent Laid-Open No. 1-92415 disclose polyethylene having a low melting point, a low melting point copolymerized polyester, a copolymerized polyethylene obtained by copolymerizing an unsaturated carboxylic acid component, and the like. A core-sheath type heat-bondable composite fiber having a sheath disposed in a sheath has been proposed.

However, it has been difficult for the conventional thermoadhesive conjugate fiber to satisfy simultaneously the texture (softness) and the strength of the nonwoven fabric and the high-speed processability during the production of the nonwoven fabric. For example, in the heat-adhesive conjugate fiber using high-pressure low-density polyethylene as the polyethylene, the melting point of the polymer is as low as about 90 ° C., so that the polymer can be heat-bonded at a low temperature and the high-speed heat-bonding processability is improved. It becomes difficult to apply crimps on the sheet, and the card passing property during the production of the nonwoven fabric is deteriorated, and the adhesiveness is poor, so that the strength of the obtained nonwoven fabric is insufficient. Further, in the heat-bondable conjugate fiber using the low-melting point polyester, it is difficult to obtain a soft one in terms of texture although the heat-bonding property is improved and the nonwoven fabric strength is good.
In addition, it is difficult to apply crimp as in the case of polyethylene. Furthermore, with the thermoadhesive conjugate fiber using the above-mentioned copolymerized polyethylene, a nonwoven fabric having good strength and soft texture can be obtained, but if the amount of the copolymerization component is increased, it becomes difficult to impart mechanical crimp, and the nonwoven fabric is manufactured. There is a problem that the card passing property at that time is lowered, the crimp applied is easily set, and the bulk durability of the nonwoven fabric becomes insufficient.

[0004]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a non-woven fabric which has good processing characteristics and thermal adhesiveness during the production of the non-woven fabric and has a soft texture. It is to provide a novel heat-bondable composite fiber suitable for obtaining.

[0005]

Means for Solving the Problems As a result of intensive studies for achieving the above-mentioned object, the present inventors have found that the melting point of the unsaturated carboxylic acid component and / or the carboxylic acid derivative copolymerized as a heat-adhesive component is 90 ° C. It has been found that the use of the following copolymerized polyethylene improves the heat-bonding processability during the production of the nonwoven fabric, improves the strength of the resulting nonwoven fabric, and makes the texture soft. However, with this, it is difficult to impart sufficient mechanical crimps to the fibers, and the durability of the crimps imparted is insufficient, and the card process passability during the production of the nonwoven fabric is reduced. There was no choice but to reduce the processing speed, and the durability of the texture of the resulting nonwoven fabric was insufficient. Therefore, as a result of further intensive study, when the above modified copolymerized polyethylene is used as a heat-adhesive component and the fiber is provided with an inverted three-dimensional crimp, sufficient crimp with good durability can be provided and the above-mentioned object can be achieved at the same time. They have found the present invention and reached the present invention.

That is, according to the present invention, a copolymerized polyethylene containing an unsaturated carboxylic acid and / or the carboxylic acid derivative as a copolymerization component, wherein the content of the copolymerization component is 6.0 to 10.0 mol%. A fiber-forming polymer having a melting point of 90 ° C. or lower and a melt index value of 1 to 20 g / 10 min as one component (A), and having a melting point higher than the melting point of the copolymerized polyethylene by 50 ° C. or more. A thermoadhesive conjugate fiber as the other component (B), wherein the fiber has a reversible three-dimensional crimp having a crimp number of 7 to 20 pieces / 25 mm. To be done.

The copolymerized polyethylene used as one component (A) of the conjugate fiber of the present invention contains an unsaturated carboxylic acid and / or the carboxylic acid derivative as a copolymerization component of 6.0.
.About.10.0 mol% must be contained. When the content of the copolymerization component is less than 6.0 mol% with respect to ethylene,
Since the melting point of the copolymerized polyethylene is not sufficiently lowered and the thermal adhesiveness is also insufficient, it is not possible to lower the thermal adhesive processing temperature during the production of the nonwoven fabric, and it is also impossible to increase the thermal adhesive processing speed. The object of the present invention cannot be achieved. On the other hand, when the copolymerization amount exceeds 10.0 mol%, not only the melting point becomes too low but the spinnability and stretchability at the time of producing the conjugate fiber deteriorates, making it impossible to stably produce the composite fiber. Since the coefficient of friction of the composite fiber with the metal becomes large, the passability of the card process during the production of the nonwoven fabric deteriorates.

The unsaturated carboxylic acid and / or its derivative preferably used are, for example, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate and acryl. Acrylic acid esters such as hydroxyethyl ester, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid-2-
Methacrylic acid esters such as ethylhexyl and hydroxyethyl methacrylate, and unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride can be used. These can be used alone or in combination of two or more kinds. Is also good.

The melting point of the copolymerized polyethylene is 90 ° C. or lower, and the melt index value (MFR) is 1 to 20 g / 1.
Must be 0 minutes. If the melting point is higher than 90 ° C., it is not preferable because if the processing speed is increased in the heat-bonding treatment step, uniform heat-bonding becomes difficult, and the feel and strength of the resulting nonwoven fabric deteriorate. If the MFR is less than 1 g / 10 minutes, the fluidity at the time of melt spinning will be lowered, so that the conjugate fiber cannot be stably produced unless the spinning speed is extremely lowered. On the other hand, when the MFR is more than 20 g / 10 minutes, the melt viscosity becomes too low to make stable composite spinning difficult, and the adhesive strength also decreases, which is not preferable.

The copolymerized polyethylene may be mixed with a small amount of other heat-adhesive components such as polyethylene and polypropylene within a range that does not impair the object of the present invention. A moisture absorbent, a matting agent, a pigment, You may mix additives, such as a stabilizer and a flame retardant.

Next, the polymer used as the other component (B) of the heat-bonded composite fiber of the present invention is fiber-forming and has a melting point of 50 ° C. or more higher than that of the A component, preferably 150. It is necessary to have a melting point of ~ 300 ° C. If the melting point of the component B is less than the above, it is not preferable because it cannot withstand the heat-bonding treatment conditions when a nonwoven fabric is produced using this composite fiber, and only a nonwoven fabric with a hard texture can be obtained.

Examples of the fiber-forming polymer preferably used include polyethylene terephthalate, polybutylene terephthalate, polyesters obtained by copolymerizing a small amount of the third component, and polypropylene. Among them, polyethylene terephthalate or a copolymerization component such as 5-sodium sulfoisophthalic acid, isophthalic acid, adipic acid, sebacic acid or the like is preferable from the viewpoints of good bulk recovery property, small shrinkage at the time of heat adhesion, low cost, etc. Acid components such as carboxylic acid and lower alkyl esters thereof, diethylene glycol, neopentyl glycol, tetramethylene glycol, propylene glycol, polyethylene terephthalate copolymer polyesters obtained by copolymerizing dihydroxy compounds such as bishydroxyphenylpyropane are preferable, On the other hand, polypropylene is preferable from the viewpoint of high affinity with the component A and good adhesive strength of the nonwoven fabric.

The composite form of the heat-bondable composite fiber of the present invention is
Either side-by-side type or core-sheath type may be used,
In order to use it as a heat-bonding fiber, 60% or more of the copolymerized polyethylene (A) is exposed on the fiber surface, and particularly a core-sheath type composite fiber in which the copolymerized polyethylene occupies the entire fiber surface is preferable. Among them, the eccentric core-sheath type composite fiber is preferable because it makes it easy to give a three-dimensional inversion type three-dimensional crimp to be described later to the fiber. The composite ratio is preferably 35 to 75% by weight of the copolymerized polyethylene (A) which is a heat-adhesive component, and 25 to 65% by weight of the fiber-forming polymer (B). When the amount of component A is large, the amount of fiber-forming components is small, and the bulk recovery of the nonwoven fabric tends to be low. On the contrary, when the amount of component B is large, the thermal adhesive component is small and the adhesive strength tends to be low.

The thermoadhesive conjugate fiber of the present invention comprises the above components A and B and has a crimp number of 7 to 2
It is essential to have 0/25 mm inverted type three-dimensional crimps, which makes it possible to obtain a good-quality non-woven fabric stably even if the processing speed during non-woven fabric production is high for the first time. Becomes When the crimp is a mechanical crimp applied by, for example, an indentation crimper, the component A has a low melting point, so that the heat setting of the crimp is insufficient and the shape retention of the crimp is insufficient. When the crimp is stretched in the nonwoven fabric manufacturing process or the bulk of the non-woven fabric is reduced during the heat-bonding treatment, a good texture cannot be obtained. However, it is not preferable because the card passing property in the non-woven fabric manufacturing process is lowered and a nep is likely to occur. Furthermore, even if it is an inverted type three-dimensional crimp, the number of crimps is 7 pieces / 25 mm.
When it is less than 20 mm, the card passing property is deteriorated, and cotton drop is likely to occur. On the other hand, when it exceeds 20 pieces / 25 mm,
Nep is likely to occur in the carding process, and the obtained nonwoven fabric has insufficient texture and bulk, which is not preferable.

In the present invention, it is more preferable that the crimps are only inverted type three-dimensional crimps, but a part of the forward type three-dimensional crimps may be present as long as the object of the present invention is not impaired.
Usually, the ratio is about 10% or less. The forward type three-dimensional crimp in the present invention is a spiral-like three-dimensional crimp, while the inversion type three-dimensional crimp is a three-dimensional crimp in which each crimp form is inverted to an omega type. Both can be easily identified.

The heat-adhesive conjugate fiber of the present invention is preferably one having a fineness of 1 to 10 denier and a fiber length of 20 to 100 mm in view of the card passing property at the time of producing a nonwoven fabric, the texture of the resulting nonwoven fabric and the like.

In order to produce the heat-bondable composite fiber of the present invention described above, a conventionally known composite spinneret is used and a copolymerized polyethylene and a fiber-forming polymer are compounded in a side-by-side type or an eccentric core-sheath type. The latent crimping property is imparted by spinning / drawing or by asymmetric cooling spinning during composite spinning / drawing into a core-sheath type, and then the number of crimps is 5 to 8/2.
After applying a mechanical crimp of about 5 mm, relaxation heat treatment may be performed at a temperature about 15 ° C. lower than the melting point of the component A. If the mechanical crimp is not applied here, the form of the crimp obtained is only the forward type three-dimensional crimp, and the fiber of the present invention cannot be obtained. As a drawing method, hot water drawing is preferable because it can be drawn at a relatively high temperature, so that the heat shrinkage rate of the obtained fiber can be suppressed.

The fibers of the present invention may be used alone or in combination with other fibers, for example, natural fibers such as cotton, semi-synthetic fibers such as rayon, synthetic fibers such as polypropylene and polyethylene terephthalate, and various fiber aggregates. It is particularly suitable for non-woven fabrics such as surface covering materials for sanitary materials such as diapers and napkins.

In order to produce a web-like fiber aggregate from the fibers of the present invention alone or a mixture with other fibers, a conventionally known non-woven fabric producing method can be adopted. For example, if the card method is adopted, 150 m / min. High-speed processing is possible. By heat-treating the obtained web-shaped fiber aggregate at a temperature about 10 to 15 ° C. higher than the melting point of the heat-bonding component of the composite fiber,
A nonwoven fabric having sufficient strength can be obtained even at a high processing speed of 150 m / min. As a method of heat treatment, a hot air dryer,
A dryer such as a suction drum dryer or a heating roll such as a flat calendar roll or an embossing roll can be used. Among them, the method using a heating roll is preferable because high-speed heat treatment can be performed even at a low temperature.

[0020]

The heat-adhesive conjugate fiber of the present invention has a melt index value of 1 to 20 g / 10 in which 6 to 10 mol% of an unsaturated carboxylic acid and / or the carboxylic acid derivative component is copolymerized as its heat-adhesive component. Since the copolymerized polyethylene is used, the processing speed can be increased even if the heat-bonding temperature when heat-treating the non-woven fabric is lowered, and a non-woven fabric exhibiting a soft texture can be obtained. To be Further, since the fiber of the present invention has 7 to 20 pieces / 25 mm of the reversible type three-dimensional crimp, it has excellent crimp durability as compared with the mechanical crimp, and the web as compared with the forward type three-dimensional crimp. As a result of remarkably improving the card passing property during the production, it becomes possible to produce a non-woven fabric of good quality with extremely high productivity.

[0021]

EXAMPLES The present invention will be described in more detail with reference to examples. Each measurement item in the examples was as follows. The peak temperature was determined using a melting point differential calorimeter. Melt index value Measured according to JIS K-8142. Card passability The obtained short fibers were passed through a roller card at a speed of 20 m / min to form a web. At this time, the card passing property was evaluated on a three-point scale and expressed by the following criteria. Normal operation is possible: ○, Operation is possible: △, Operation is not possible:
Basis weight It conformed to JIS P-8142. Pulling strength According to JIS L-1096 strip method, width 30m
The maximum tensile strength of a test piece of m and a length of 100 mm was determined.

[Example 1] The copolymer polyethylene shown in Table 1 was used as a sheath component and phenol / tetrachloroethane (1
/ 1) Using polyethylene fiber terephthalate having an intrinsic viscosity of 0.68 measured with a mixed solvent as a core component and using a composite fiber melt spinning device, a melting temperature of copolymerized polyethylene from an eccentric core-sheath type composite spinneret with 600 holes. It was melt extruded at 220 ° C., the melting temperature of polyethylene terephthalate was 285 ° C., the single hole discharge rate was 1.2 g / min, and the core / sheath composite ratio was 55/45. 5 m ³ of cooling air with a temperature of 35 ° C is applied to the spun yarn from one direction.
After spraying at a rate of 1 / min, the mixture was cooled and solidified, and then wound at a speed of 1200 m / min. The obtained undrawn yarn has a drawing temperature of 70 ° C.
18 times, 1.1 times at 80 ° C (3.5 times total draw ratio) 2
Stepwise hot water drawing, 5 crimps / 25m with push-in type crimper
m, and then subjected to a relaxation heat treatment at 60 ° C. for 40 minutes to express 18 reversal three-dimensional crimps / 25 mm and then cut to obtain short fibers having a fiber length of 51 mm and a single fiber fineness of 3.5 denier. The cross-sectional shape of the fiber of this product is shown in FIG.

The obtained heat-adhesive conjugate fiber was applied to a high-speed card machine of 150 m / min to make a web having a basis weight of 20 g / m ² , and then heat-bonded at a processing speed of 150 m / min using an embossing roll heated to 85 ° C. A non-woven fabric was obtained by processing. The performance of the obtained nonwoven fabric is shown in Table 1.

Example 2 The heat-adhesive conjugate fiber produced in Example 1, a single fiber fineness of 3.0 denier and a fiber length of 51 m.
m and a polyethylene terephthalate short fiber having 12 crimps / 25 mm were mixed so that the mixing weight ratio was 50/50, and then a nonwoven fabric was obtained in the same manner as in Example 1. The results are also shown in Table 1.

[Comparative Example 1] A short fiber having a fiber cross-sectional shape shown in FIG. 2 was obtained in the same manner as in Example 1 except that the composite form was a concentric core-sheath type. Since the obtained short fibers hardly exhibit inverted three-dimensional crimps and are less susceptible to mechanical crimps, the number of crimps is 10 to 15/25 mm.
I was scattered. It was attempted to produce a web by directly applying the obtained fiber to a card, but the fiber was wound around a cylinder and could not be stably operated.

[Examples 3 to 7, Comparative Examples 2 to 8] Example 1
In, a nonwoven fabric was obtained in the same manner as in Example 1 except that the copolymerized polyethylene was changed to that shown in Table 1. Since the stretchability was poor in Comparative Example 3, the total stretch ratio was set to 2.3 (single fiber fineness 4.4 denier).

Further, in Comparative Example 2, since the melting point of the copolymerized polyethylene was 108 ° C., the heat bonding temperature was 110 ° C.,
At a processing speed of 120 m / min, sufficient adhesive strength could not be obtained.

[0028]

[Table 1]

[0029]

EFFECTS OF THE INVENTION According to the thermoadhesive conjugate fiber of the present invention, since it has an inversion type three-dimensional crimp having good durability, it has excellent card passing property and can stably produce a web even at a high speed. be able to. Further, since the melting point of the heat-adhesive component is low, it is possible to produce a sufficiently strong nonwoven fabric with high productivity even if the heat-adhesion processing speed is high. Furthermore, since the heat-adhesive component is a modified polyethylene obtained by copolymerizing ethylene with an unsaturated carboxylic acid component, a strong non-woven fabric exhibiting a soft texture can be obtained and used as a surface coating material for disposable diapers, sanitary products, etc. It is preferably used.

[Brief description of drawings]

FIG. 1 is an example of a fiber cross-sectional view of a heat-bonded conjugate fiber of the present invention manufactured in Example 1.

FIG. 2 is an example of a fiber cross-sectional view of a heat-bondable conjugate fiber outside the present invention produced in Comparative Example 1.

[Explanation of symbols]

1 sheath component 2-core component

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-1-92415 (JP, A) JP-A-1-266217 (JP, A) JP-A-1-272823 (JP, A) JP-A-5- 321033 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D01F 8/00-8/18

Claims (3)

(57) [Claims] 1. A copolymerized polyethylene containing an unsaturated carboxylic acid and / or a carboxylic acid derivative as a copolymerization component, wherein the content of the copolymerization component is 6 to 10 mol%, the melting point is 90 ° C. or lower, and the melt. Index value is 1 to 20g / 1
A thermoadhesive conjugate fiber comprising 0 minute copolymer polyethylene as one component (A), and a fiber-forming polymer having a melting point of 50 ° C. or more higher than the melting point of the copolymer polyethylene as the other component (B). , The number of crimps of the fiber is 7 to 20/2
A thermoadhesive conjugate fiber, which has an inverted three-dimensional crimp of 5 mm. 2. The heat-adhesive conjugate fiber according to claim 1, wherein the fiber-forming polymer is polyethylene terephthalate, a derivative thereof, polybutylene terephthalate, a derivative thereof, or polypropylene. 3. The heat-bondable conjugate fiber according to claim 1, wherein the conjugate fiber is an eccentric core-sheath type conjugate fiber.