JPH08325937A - Thermally fused conjugated fiber having hydrophobic property - Google Patents

Abstract

PURPOSE: To obtain a hydrophobic and thermally fused conjugated fiber excellent in hydrophobic durability and having good passing-through property of heat- treating process in producing a nonwoven fabric. CONSTITUTION: A surface treating agent having 14-18C alkyl group and containing >=70wt.% alkyl phosphate containing 50-90wt.% potassium salt and 10-50wt.% sodium salt is attached in an amount of 0.1-5.0wt.% based on a fiber onto the surface of thermally fused conjugated fiber composed of a polyolefin or polyester having 50-150 deg.C melting point and/or softening initiating temperature and a fiber forming polymer having a melting point higher than that of the polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-fusible composite fiber exhibiting excellent hydrophobicity and durability, and particularly suitable for sanitary material face covers such as disposable diapers and sanitary products. It is about.

[0002]

2. Description of the Related Art Conventionally, sanitary materials such as disposable diapers and sanitary products are covered with hydrophobic fibers such as pulp, rayon cotton, absorbent cotton, etc., which have a high water absorbing property. There is known a technique of suppressing the backflow of the drainage absorbed by the absorber through the face cover and imparting a good skin feel and the like by performing the treatment with (1) (for example, JP-B-63-14081). , Shokoku Sho 6
3-24116). Further, in these methods, it has been recently proposed to use a heat-adhesive conjugate fiber containing a polyolefin or a low-melting point polyester having a hydrophobic treatment agent attached to at least a part of the hydrophobic fiber as a heat-adhesive component. (See JP-A-3-19969 and JP-A-5-321156).

[0003]

However, in the method proposed in Japanese Patent Laid-Open No. 3-19969, the treating agent used is mainly composed of an alkyl phosphate potassium salt having 18 to 20 carbon atoms. However, although the one showing good hydrophobicity can be obtained, its level is insufficient for a sanitary material face cover, and there is a drawback that the processing speed in the nonwoven fabric manufacturing process cannot be increased. On the other hand, the method proposed in Japanese Patent Laid-Open No. 5-321156 uses a surface treatment agent containing a silicon-based treatment agent and an amine-based treatment agent, and therefore exhibits good hydrophobicity under a condition where pressure is not too much. However, under the condition that back pressure is applied, the hydrophobicity is insufficient, that is, the hydrophobic durability is insufficient, and further, the static electricity suppressing effect in the heat treatment step during the production of the nonwoven fabric is insufficient, and the sheet is wound around the roller. There was a problem of frequent occurrence.

An object of the present invention is to provide a hydrophobic heat-fusible composite fiber which is improved in the above problems of the prior art and which is excellent in hydrophobic durability and has good passability in a heat treatment step during the production of a nonwoven fabric. To do.

[0005]

Means for Solving the Problems The inventors of the present invention have made earnest studies to achieve the above object, and as a result, when adding a treating agent containing an alkyl phosphate salt having 14 to 18 carbon atoms as a main component, the phosphate salt was added. As a result, they have found that the combined use of a sodium salt in addition to a potassium salt can improve the hydrophobic durability without lowering the passability in the nonwoven fabric manufacturing process, and arrived at the present invention.

That is, according to the present invention, at least one thermoplastic polymer selected from polyolefins and polyesters having a melting point and / or a softening start temperature of 50 to 150 ° C. and a melting point higher than that of the thermoplastic polymer are used. A heat-fusion conjugate fiber composed of a fiber-forming polymer having an alkyl group having 14 carbon atoms on the surface of the conjugate fiber.
And the proportion of potassium salt is 50 to 90% by weight,
Hydrophobicity, characterized in that a surface treatment agent containing 70% by weight or more of an alkyl phosphate salt in which the proportion of sodium salt is 10 to 50% by weight is attached in an amount of 0.1 to 5.0% by weight based on the weight of the fiber. Heat-fusible composite fibers are provided.

The alkyl phosphate salt contained in the surface treating agent used in the present invention has an alkyl group having 14 to 18 carbon atoms and a potassium salt ratio of 50.
~ 90% by weight, the proportion of sodium salt is 10 to 50% by weight
Is essential. Conventionally, as the alkyl phosphate salt, a potassium salt has been used because of its properties such as solubility in water, viscosity of an aqueous solution, stability of a conditioning treatment agent over time, and antistatic property. It was found that by changing a part of the potassium salt to a sodium salt, the hydrophobic durability is improved and the hydrophobic durability of the obtained fiber is further improved over time.

If the proportion of sodium salt is less than 10% by weight, the above effect is not exhibited, while if it exceeds 50% by weight, the effect of suppressing the generation of static electricity becomes insufficient and the nonwoven fabric manufacturing process ( Card process) Passability deteriorates,
It is not preferable because the texture of the obtained sheet is extremely deteriorated.

When the number of carbon atoms is less than 14, the hydrophobicity is lowered and the surface treating agent becomes tacky, which lowers the permeability in the fiber and nonwoven fabric manufacturing process. On the other hand, when the number of carbon atoms exceeds 18, the solubility of sodium salt in water is lowered, so that the object of the present invention cannot be achieved, which is not preferable. Particularly preferably used is a cetyl phosphate salt having an alkyl group having 16 carbon atoms, which is more excellent in solubility in water, hydrophobic durability of the obtained fiber, and process stability of the nonwoven fabric manufacturing process.

Further, in the present invention, it is preferable that 30% by weight or less of the alkyl phosphate salt is an amine salt within the range satisfying the above in order to suppress the generation of static electricity. In this case, the alkyl group of the alkyl phosphate is preferably the same as the alkyl group of the potassium salt in order to simplify the synthetic process of the treating agent. On the other hand, the amine is not particularly limited, but trialkylamine is particularly preferable because it has a large antistatic effect, and for example, trimethylamine and triethylamine are preferably used.

Such alkyl phosphate salts are usually
It is produced by adding powdered anhydrous phosphorus pentoxide to the corresponding alcohol, reacting it with heating, and then neutralizing it with potassium hydroxide, sodium hydroxide or an amine. Then, a mixture of a monoalkyl phosphate salt, a dialkyl phosphate salt, and a polyalkyl polyphosphate salt can be obtained by variously changing the reaction conditions, the neutralization conditions and the like. The reaction ratio of the alcohol to phosphorous oxide (degree of phosphorylation: molar ratio) is 2.5 to 3.
In the range of 5, especially in the range of 2.7 to 3.0, the object of the present invention is highly achieved and preferred.

The surface treating agent in the present invention must contain the above alkyl phosphate salt in an amount of 70% by weight or more. If the content is less than 70% by weight, not only the hydrophobic durability of the obtained fiber becomes insufficient, but also the process stability at the time of manufacturing the fiber or the nonwoven fabric decreases, which is not preferable. Other components that can be used together within the range of 30% by weight are optional as long as they do not impair the hydrophobic durability, and are used for ordinary fiber treatment agents such as other leveling agents, sizing agents, antistatic agents, water repellents, etc. What has been done can be used. In particular, when post-processing under low humidity, it is necessary to prevent electrification, so it is preferable to add an antistatic agent of 30% by weight or less to make the specific resistance 9.5 × 10 ⁸ Ω or less. Further, in order to further improve the hydrophobic durability, it is preferable to add a fluorine-based water repellent in an amount of 1 to 10% by weight, preferably 2 to 5% by weight.

The antistatic agent which is preferably used is an ethylene oxide adduct of a monoalkylamine in order to balance hydrophobicity. Particularly, the amine-based treating agent represented by the following formula is compatible with the alkylphosphate salt. It is also preferable because it exhibits excellent antistatic properties. RN [(C ₂ H ₄ O) _m H] (C ₂ H ₄ O) _n H Here, R represents an alkyl group having 8 to 22 carbon atoms, preferably 12 to 18 carbon atoms, and particularly a hydrophobic group in which a stearyl group can be obtained. Both durability and antistatic property are favorable, which is preferable. Further, m and n are (m + n) 5 to 40, especially 12 to 2
A positive integer of 5 is preferable from the viewpoint of good antistatic effect and low skin irritation. Specific examples include laurylamine, myristylamine, cetylamine, and stearylamine to which 5 to 40 mol of ethylene oxide is added.

As the antistatic agent other than the above, an alkylphosphate metal salt having an alkyl group having a small number of carbon atoms can be used within a range that does not impair the object of the present invention.
Examples thereof include lauryl phosphate potassium salt and octyl phosphate potassium salt. Furthermore, a phosphate salt (sometimes referred to as an EO-added alkyl phosphate salt) synthesized from an alcohol obtained by adding several moles of ethylene oxide can also be used.

As the fluorine-based water repellent which is preferably used, a perfluoroalkyl group-containing vinyl polymer is preferably used, and for example, polyperfluorooctyl acrylate is preferable because it provides good hydrophobic durability. If the addition amount is too large, not only the effect of hydrophobicity is saturated, but also the hydrophobic durability is lowered,
Since the cost becomes high, it is preferable to set it to 1 to 10% by weight or less.

In the present invention, the amount of the surface treatment agent attached should be 0.1 to 5.0% by weight, preferably 0.2 to 1.0% by weight, based on the weight of the fiber. If the adhesion amount is less than 0.1% by weight, not only the hydrophobic durability becomes insufficient, but also the effect of preventing the generation of static electricity becomes insufficient and the process stability during fiber production or nonwoven fabric production decreases. It is not preferable. On the other hand, when it exceeds 5.0% by weight, not only the adhesiveness of the obtained fiber is increased and the process stability is lowered, but also the adhesive strength when formed into a nonwoven fabric tends to be lowered. The application of the surface-treating agent may be carried out by diluting with water to form an aqueous emulsion, at any stage of fiber production, particularly in an oiling step which is usually carried out in the process of stretching heat treatment of the fiber, Simple and desirable.

Next, the fiber to which the above-mentioned surface treatment agent is applied is made of at least one thermoplastic polymer selected from polyolefins and polyesters having a melting point and / or a softening start temperature of 50 to 150 ° C. (heat fusion component). And a fiber-forming polymer having a melting point higher than that of the thermoplastic polymer. When the heat-sealing component is other than the above, for example, in the case of a copolyamide, it becomes difficult to uniformly apply the surface treatment agent onto the fiber, and the strength when formed into a nonwoven fabric is also reduced. Tend to do.

The heat-bonding component usually has a heat-bonding temperature of 150 to 170 ° C. during the production of a nonwoven fabric, so that its melting point and / or softening start temperature must be 150 ° C. or lower. On the other hand, when crimping the composite fiber, it is required that it can be heat-set at a temperature as high as possible, or that the resulting nonwoven fabric is not remelted by hot water or the like, so the melting point and / or softening start temperature of the heat-sealing component is It should be 50 ° C or higher, preferably 90 ° C or higher.

Examples of polyolefins among such heat-sealing components include (co) polymers containing olefins such as ethylene, propylene, butene-1 and pentene-1 as the main components, and An unsaturated carboxylic acid such as acrylic acid, methacrylic acid, fumaric acid, itaconic acid or crotonic acid, and a copolymer (including graft copolymerization) of these esters or acid anhydrides can also be used.

As the polyester, any polyester may be used as long as it satisfies the requirements for the melting point and / or the softening start temperature. Among them, terephthalic acid, isophthalic acid, adipic acid and sebacine are used as the acid component. acid,
A copolymerized polyester using 5-sodium sulfoisophthalic acid or the like and ethylene glycol, propylene glycol, tetramethylene glycol, diethylene glycol, neopentyl glycol or the like as a glycol component on the other hand is preferable because it is inexpensive and has good adhesiveness.

The other component constituting the conjugate fiber of the present invention is not particularly limited as long as it is a fiber-forming polymer and has a melting point higher than that of the heat-sealing component, but it is usually from the viewpoint of cost. Is preferably polypropylene or polyethylene terephthalate. Of course, depending on the application, it may be desirable to use an aliphatic polyamide such as nylon-6 or nylon-6,6.

The composite form of the above-mentioned components is mainly intended for a core-sheath type or an eccentric core-sheath type, but when the fiber-forming component is polyester or polyolefin, it is a side-by-side type, that is, a fiber-forming component and a heat-sealing component. It may be a pasted one. Also, the cross-sectional shape is round, flat, T
It may be in any form such as a multi-leaf modified cross section such as a mold or a hollow cross section.

The heat-fusible conjugate fiber of the present invention has a fineness of 1 to 15 denier, a crimp number of 6 to 30/25 mm, and a fiber length depending on the card passing property during the production of the nonwoven fabric, the texture of the resulting nonwoven fabric, and the like. Those of 30 to 80 mm are suitable.

The fiber of the present invention contains other fibers, if necessary.
For example, natural fibers such as cotton, semi-synthetic fibers such as rayon, synthetic fibers such as polypropylene and polyethylene terephthalate are mixed in an amount of 50% by weight or less, and preferably the fibers of the present invention alone are used as various fiber aggregates, In particular, it is suitable for a non-woven fabric such as a surface covering material for sanitary materials such as diapers and napkins. When other fibers are mixed, it is desirable that the same treatment agent as that previously attached to the fibers of the present invention is attached to the surface of the fibers.

In order to produce, for example, a web-shaped 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, when the card method is adopted, 150 m is used. High-speed machining of / minute is possible. The obtained web-like fiber aggregate is sufficiently strong even at a high processing speed of 150 m / min by being heat-treated at a temperature about 10 to 15 ° C. higher than the melting point or softening point of the heat-sealing component of the composite fiber. Can be made of a non-woven fabric. As a method of heat treatment, any of a dryer such as a hot air dryer and a suction drum dryer, and a heating roll such as a flat calender roll and an embossing roll can be used. Above all, linear pressure of 40K using a heating roll
The method of thermocompression bonding at about g / cm is preferable because high-speed heat treatment can be performed even at a low temperature.

[0026]

The hydrophobic heat-fusible composite fiber of the present invention is an alkyl phosphate salt having an alkyl group having a specific carbon number on the surface of the fiber, of which the proportion of sodium salt is 10%.
.About.50% by weight and a potassium salt ratio of 90 to 50% by weight are added to the surface treatment agent as a main component, so that a fiber structure having good hydrophobic durability can be obtained. Although the detailed reason is still unknown, it has a feature that its hydrophobic durability improves with time. Moreover, since it is excellent in the card process passability, it is possible to stably produce a good-quality non-woven fabric even when it is operated at a high speed.

Further, since the fiber of the present invention uses polyolefin or polyester as its heat-fusible component, the surface treatment agent does not inhibit the adhesion during the heat-adhesion treatment, and has a soft texture. The presented non-woven fabric can be obtained.

[0028]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Each measurement item in the examples was as follows. Card passability Short fibers with a cut length of 51 mm are put on a roller card at a speed of 2
The web passed through at 0 m / min. Passability at this time is 3
It was evaluated in stages and expressed by the following criteria. Normal operation: ○ Operation is possible: △ Operation is not possible: × Static electricity amount in card process: Temperature of 25 ℃, humidity of 45%, speed of 25m / min. The amount was measured with a model KS-525 manufactured by Kasuga Electric Co., Ltd. Heat treatment process passability The passability when the adhesive treatment was performed using a metal mirror-made roller at a processing speed of 30 m / min, a roller temperature of 120 ° C., and a roller linear pressure of 40 Kg / cm was evaluated in three stages and expressed by the following criteria. Can be operated normally: ○ Can be operated once: △ Can not be operated because the sheet rises up: × Adhesive strength Creates a web with a basis weight of 30 g / m ² from short fibers with a cut length of 51 mm, and then heat treats it at 140 ° C for 20 seconds to form a nonwoven fabric . From the obtained nonwoven fabric, width 6c in the machine direction
Cut a test piece of m and 20 cm in length, and hold it at a gripping interval of 10
The breaking strength is measured at cm and a pulling speed of 20 cm / min. The adhesive strength is a value obtained by dividing the breaking strength by the weight of the test piece. Hydrophobic durability According to JIS A1003 durability A method, 2 with hot air dryer
The water resistance of a non-woven fabric having a basis weight of 25 g / m ² treated at 50 ° C. for 2 minutes was measured, and the water level was displayed in cm. The liquid used was physiological saline and 28 ° C. Changes in hydrophobic durability over time 20% of the resulting nonwoven fabric was stored under conditions of a temperature of 30 ° C. and a humidity of 65%.
The hydrophobic durability after aging for days was measured and expressed by the increment. Take 2 g of short fiber opened through a resistivity card and keep the temperature at 25 ° C.
TR8 manufactured by Advantest Co., Ltd. under the condition of a humidity of 65%
It was measured using Model 611A.

[Example 1] High-density polyethylene having a melting point of 125 ° C was used as a sheath component (heat-sealing component), and polyethylene terephthalate having an intrinsic viscosity of 0.64 was used as a core component (fiber-forming component), and a pore diameter was 0.5 mmφ. Using a core-sheath type composite spinneret with 260 holes, the core component is 285 ° C and the sheath component is 250
It was melted at ℃ and discharged at a base temperature of 275 ℃. At this time, the composite ratio was 50/50. The unstretched yarns were combined to make 170,000 denier, then stretched 2.7 times at 80 ° C., then various surface treatment agents shown in Table 1 were applied, and 15 / A crimp of 25 mm was applied, a relaxation heat treatment was performed at 100 ° C. for 30 minutes, and then cutting was performed to obtain a short fiber having a single yarn fineness of 3 denier and a fiber length of 51 mm. This short fiber was applied to a roller card to form a web having a basis weight of 30 g / m ² at a speed of 25 m / min, then using a metal mirror surface roller with a roller temperature of 120 ° C., a processing speed of 30 m / min and a roller linear pressure of 4
A non-woven fabric was obtained by performing an adhesion treatment at 0 Kg / cm. Table 2 shows the performance of the obtained heat fusion-bonded composite fiber and nonwoven fabric. In addition,
As the phosphate salt in the table, one having a phosphorylation degree of 2.9 was used.

[0030]

[Table 1]

[0031]

[Table 2]

[Example 2] A low melting point polyester (acid component: terephthalic acid / isophthalic acid = 8 /
2 (molar ratio), glycol component: hexamethylene glycol / ethylene glycol = 9/1 (molar ratio), melting point:
106 ° C.) or a polyolefin / polyester mixture (high density polyethylene having a melting point of 125 ° C./low melting point polyester / maleic acid modified polyethylene (melting point 114)
C.) = 6/2/2) is used, and as the surface treatment agent, Experiment No. 1 of Example 1 is used. A composite fiber and a non-woven fabric were obtained in the same manner as in Example 1 except that the same one as used in 7 was used.
The results are shown in Table 3.

[0033]

[Table 3]

Example 3 A high density polyethylene having a melting point of 125 ° C. was used as a heat-sealing component, and a crystalline polypropylene having a melting point of 165 ° C. was used as a fiber-forming component to obtain a composite fiber having a cross-sectional shape shown in Table 4. , Then implementation No. The same surface treatment agent used in 7 or 12 was applied. The die temperature was 250 ° C., the stretching temperature was 80 ° C., the stretching ratio was 3.0 times, and the composite ratio was 50/50. The results are shown in Table 4.

[0035]

[Table 4]

[0036]

EFFECT OF THE INVENTION According to the hydrophobic heat-fusible composite fiber of the present invention, a non-woven fabric having extremely excellent hydrophobic durability can be easily produced and used as a surface coating material for sanitary materials such as disposable diapers and sanitary products. It can be preferably used.

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Claims (3)

[Claims] 1. A melting point and / or a softening start temperature of 50 to 1
A heat-fusion composite fiber comprising at least one thermoplastic polymer selected from polyolefins and polyesters and a fiber-forming polymer having a melting point higher than that of the thermoplastic polymer at 50 ° C. The surface of the fiber has 14 to 18 carbon atoms in the alkyl group, 50 to 90% by weight of potassium salt, and 1% of sodium salt.
A surface treatment agent containing 70% by weight or more of an alkyl phosphate salt of 0 to 50% by weight is 0.1% with respect to the fiber weight.
A hydrophobic heat-sealing composite fiber characterized by being adhered in an amount of up to 5.0% by weight. 2. The hydrophobic thermal fusion bonding fiber according to claim 1, wherein the proportion of the amine salt in the alkyl phosphate salt is 30% by weight or less. 3. The surface treatment agent comprises 1 to 1 of a fluorine-based water repellent agent.
The hydrophobic thermal fusion bonding fiber according to claim 1 or 2, containing 0% by weight.