JP3254423B2 - Manufacturing method and use of water-absorbing fiber having antibacterial property - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an absorbent body made of a nonwoven fabric which is suitably used for sanitary products, incontinence shorts, and diapers.

[0002]

2. Description of the Related Art Conventionally, resins or fibers obtained by replacing an alkali metal salt of a carboxyl group in a polymer with an antibacterial metal ion have been used as a resin or a fiber having both a water absorbing property and an antibacterial property. For example, JP-A-63-200837 discloses a water-absorbing antibacterial resin having both water-absorbing performance and antibacterial performance by exchanging an alkali metal salt of a carboxyl group in a water-absorbing resin with an antibacterial metal ion. However, since such a resin exchanges metal ions in a water solvent, the resins adhere to each other during washing and drying after the exchange, and the resin cannot maintain its initial form and becomes powder. For this reason, when it is added to a non-woven fabric, there is a problem that a part of the non-woven fabric falls off during the manufacturing process.

Japanese Patent Application Laid-Open No. 09-28539 discloses a water-absorbing fiber having both water-absorbing performance and antibacterial performance by exchanging an alkali metal salt of a carboxyl group in the water-absorbing fiber with an antibacterial metal ion. However, since such water-absorbent fibers also exchange metal ions in a water solvent, the resins adhere to each other and become hardened during washing and drying after the exchange. For this reason, in addition to the problem that a part becomes powder in the manufacturing process like a water-absorbent resin and falls off, when mixed with other fibers to create a nonwoven fabric absorbent, the texture becomes hard, and sanitary products and incontinence There is a problem that it is unsuitable for applications that directly contact the skin, such as shorts and diaper absorbers.

[0004]

SUMMARY OF THE INVENTION The present invention retains the initial form even after the exchange of the antibacterial metal ions, has less falling off in the manufacturing process, is mixed with other matrix fibers, and is used for the nonwoven fabric absorbent. An object of the present invention is to provide a method for producing a water-absorbing fiber having a good texture even if it is produced.

[0005]

Means for Solving the Problems The present inventors studied a method for producing a fiber and completed the present invention. That is, a method for producing a water-absorbing fiber comprising a polymer containing a carboxyl group and a metal salt thereof, wherein a part of the metal salt contains an antibacterial metal ion, and an exchange reaction of the antibacterial metal ion in 1-propanol. A method for producing a water-absorbent fiber.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The monomer for providing a carboxyl group in the polymer of the water-absorbent fiber used in the present invention is not particularly limited. For example, acrylic acid, methacrylic acid,
Maleic acid, maleic anhydride, fumaric acid, itaconic acid, sorbic acid, cinnamic acid, crotonic acid, β-acryloxypropionic acid, and alkali metal salts thereof can be used.

In order to impart antibacterial performance, an exchange reaction of antibacterial metal ions is performed on these carboxyl groups and alkali metal salts thereof. At this time, it is necessary to carry out the exchange reaction in 1-propanol. When not in 1-propanol, the resins adhere and harden during washing and drying after the antibacterial metal ion exchange. For this reason, the initial form cannot be maintained, and a part of the fibers becomes powder, and the fibers fall off in the manufacturing process. Further, when mixed with other fibers, the texture becomes hard, and therefore, it is unsuitable for use in direct contact with skin, such as sanitary products, incontinence shorts, and absorbent articles for diapers.

The exchange reaction can use a dipping method. The water-absorbing fiber before the treatment is immersed in 1-propanol containing a predetermined concentration of antibacterial metal ions for a certain period of time, and then filtered. At the time of filtration, washing with 1-propanol is performed to remove unreacted substances.

Thereafter, drying is carried out.
It is preferably performed at 0 ° C. Within this temperature range, the occurrence of cross-linking in the polymer of the water-absorbing fibers due to heat treatment is small. For this reason, the influence on water absorption performance is small, which is preferable.

Preferably, the concentration of the antibacterial metal ion in the water-absorbing fiber is 10 ppm or more. In this case, sufficient antibacterial performance is obtained, and the antibacterial performance is maintained even after long-term use, which is preferable.

The antibacterial metal ion preferably contains at least one of silver, copper and zinc. These metal ions are preferable because they are safe and harmless to the human body as compared with other antibacterial metal ions, for example, arsenic, mercury and the like, and are also inexpensive.

In the case of these metal ions, 10p
It is known that the growth of microorganisms is completely inhibited at a very small concentration of at least pm (T. Sugio, Agric. Bi).
ol. Chem. , 45, 2037, 1981).

Although the antimicrobial mechanism of these metal ions is not completely elucidated, the metal ions are actively incorporated into the body of the microorganism and selectively react with the enzyme.
It is said to result in enzyme inhibition. As a result, the specificity for the target is lower than that of organic antibacterial agents such as chitin and chitosan. Therefore, it is known that growth is inhibited almost equally to bacteria, yeast, and mold.

The water absorption of these water absorbing fibers is 10 g / g.
It is preferable that it is above. When it is 10 g / g or more,
It is preferable that a nonwoven fabric is prepared by blending with other fibers and used for sanitary products, incontinence shorts, absorbent articles for diapers, etc., since sufficient absorbency to blood and body fluids can be maintained.

The water-absorbing fiber used in the present invention is mixed with a matrix fiber and used as a nonwoven fabric absorbent. Matrix fibers include synthetic fibers and natural fibers, but are not particularly limited. When using synthetic fibers, for example, acrylic
Modacrylic, polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, and copolymers thereof can be used. Further, a mixture of two or more of these may be used. When using natural fibers, for example, cellulose, wool, cotton, silk and the like can be used. Further, a mixture of two or more of these may be used.

At this time, it is necessary to contain 5 to 50% by weight of the water-absorbing fiber. If the content is less than 5% by weight, the water absorption performance is insufficient. However, if the content exceeds 50% by weight, the fibers will fall off during the production process, which is inappropriate.

The above-mentioned water-absorbent fiber and matrix fiber are opened and mixed, then a card is formed through a card, and needle punching is performed to produce a nonwoven fabric absorbent.

At this time, it is also possible to mix a binder fiber in order to obtain suitable moldability. The binder fibers are softened or melted by heating to a temperature lower than the softening point of the water-absorbing fibers and the matrix fibers, thereby exhibiting the fusibility.

The fusion temperature varies depending on the type of the matrix fiber used. For example, when a regular polyester fiber is used, the temperature is preferably 130 ° C. or lower in consideration of the influence of heating on the matrix fiber and the water-absorbing fiber. .

As such a binder fiber, a copolymer or a blend polymer, for example, a copolymer whose melting point is lowered by a copolymer component such as isophthalic acid, or a heat fusion polymer such as a blend polyester is preferably used. The heat treatment is performed at a temperature lower than the softening point temperature of the matrix fiber and at a temperature higher than the temperature at which the binder fiber exhibits the fusibility, but it can be performed as a single step or in conjunction with the heat molding step. By such heat treatment, the constituent fibers intersecting with the binder fibers adhere at the intersections to impart morphological stability to the nonwoven fabric substrate, and also to intentionally impart irregularities to the surface of the nonwoven fabric.

The binder fiber but may be a single component fiber having the above-described heat-sealing polymer, the use of the sheath-core type conjugate fibers and heat-fusible copolymer and a homopolymer as the core component and sheath component, It is more preferable because the heat-sealing function can be performed while maintaining the support function of the core component.

[0022]

According to the present invention, even if the antibacterial metal ion is exchanged, the initial form is maintained, the falling off in the manufacturing process is small, and the nonwoven fabric absorbent is made by mixing with other matrix fibers. This is a method for producing a water-absorbing fiber having a good texture.

[0023]

EXAMPLES (Method of Measuring and Evaluating Shape Retention after Antibacterial Metal Ion Exchange Treatment) The shape retention of the sample before and after the antibacterial metal ion exchange treatment was visually confirmed. The evaluation was evaluated as ◎ when the water-absorbing fiber retained the form before the antibacterial metal ion exchange treatment, as ○ when partially retaining the form, and Δ when not retaining the form.

(Method of Measuring and Evaluating Antibacterial Metal Ions in Water Absorbing Fiber) The antibacterial ions in the water absorbing fiber after the antibacterial metal ion exchange treatment were subjected to atomic absorption analysis and quantified. The evaluation was ◎ when the antibacterial ion concentration in the water-absorbing fiber was 100 ppm or more, ◎ when the concentration was 10 ppm or more and less than 100 ppm, and 1 ppm or more and 10 pp.
If it is less than m, it was evaluated as x if it was less than 1 ppm.

(Method for Measuring and Evaluating Liquid Absorbency) 0.5 g of the water-absorbing fiber after the antibacterial metal ion exchange treatment was collected, placed in a tea bag, and sufficiently immersed in ion-exchanged water. After this, let it rest on a 40 mesh wire mesh,
Measure the weight after the drops have stopped falling, and measure 1 g of fiber.
The liquid absorption per unit was determined. The evaluation was ◎ for a liquid absorption of 80 g / g or more, ○ for 50 g / g or more and less than 80 g / g,
Less than △.

(Measurement method and evaluation method of antibacterial property) Test bacteria (Staphylococcus aureus) 8.0 × 10
0.2 ml of the ⁴ / ml suspension is added to a vial and the viable cell count is determined. Next, 0.2 g of a sample was added, and the mixture was added at 37 ° C for 18 hours.
After the shaking culture, the number of viable cells was measured again to determine the sterilization rate according to the following equation. Sterilization rate (%) = (viable cell number before shaking−viable cell number after shaking) × 10
0 / (viable cell count before shaking) The evaluation was evaluated as ◎ when the sterilization rate was 95% or more, ○ when 85% or more and less than 95%, and Δ when less than 85%.

(Method of Measuring and Evaluating Hand of Nonwoven Fabric) Based on the cantilever method of JIS L 1096.
A nonwoven fabric sample is cut into a width of 2 cm and a length of 15 cm, and one end is gradually moved from a 45 ° slope. At this time, the movement distance of the point where one end touches the slope is measured. The evaluation is as follows: Movement distance less than 2 cm ◎ 2 cm or more and less than 5 cm
5 cm or more and less than 15 cm were evaluated as △, and 15 cm even when one end did not contact the slope was evaluated as x.

Example 1 Belle Oasis, a water-absorbing fiber composed of a polymer containing a carboxyl group and an alkali metal salt thereof (Kanebo Gosen Co., Ltd.)
0.1 g) was immersed in 50 ml of 1-propanol and left at room temperature for 10 minutes. After this, 1-propanol 5
0.0001 mol of silver perchlorate was added to 0 ml, and the mixture was allowed to stand at room temperature for 1 hour while shielding from light, thereby replacing the alkali metal salt in the bell oasis with silver ions. Thereafter, the mixture was separated by filtration, washed with 1-propanol, and then heated in a dryer at 80 ° C. for 2 hours to be dried. The shape of the obtained water-absorbing fiber retained the shape before silver ion exchange, and no change was observed. The silver ion concentration in the water absorbing fiber was 1980 pp.
m. Further, the liquid absorption with respect to ion-exchanged water is 95
g / g. Table 2 shows the evaluation results.

Next, using these water-absorbing fibers, a nonwoven fabric absorbent having the composition shown in Table 1 was prepared by a conventional card and needle punch. The sterilization rate of the produced nonwoven fabric absorbent against Staphylococcus aureus was 97.5%. The moving distance of the nonwoven fabric by the cantilever method was 1.5 cm. Table 2 shows the evaluation results.

Example 2 Under the same conditions as in Example 1, the alkali metal salt in the bell oasis was replaced with silver ions. Next, using these water-absorbing fibers, a nonwoven fabric absorbent having the composition shown in Table 1 was used for a normal card,
After performing needle punching, it was prepared by performing a heat treatment at 140 ° C. for 10 minutes. The sterilization rate of the prepared nonwoven fabric absorbent against Staphylococcus aureus was 96.9%.
The moving distance of the nonwoven fabric by the cantilever method is 2.5
cm. Table 2 shows the evaluation results.

Comparative Example 1 In Example 1, the same conditions were used except that the solvent for exchanging the alkali metal salt in the bell oasis with silver ions was changed from 1-propanol to ion-exchanged water. The shape of the obtained water-absorbing fiber partially retained the shape before silver ion exchange. The silver ion concentration in the water-absorbing fiber is 1860 pp.
m. Further, the liquid absorption with respect to ion-exchanged water is 92
g / g. Table 2 shows the evaluation results.

Next, using these water-absorbing fibers, a nonwoven fabric absorbent having the composition shown in Table 1 was prepared by a conventional card and needle punch. The sterilization rate of the prepared nonwoven fabric absorbent against Staphylococcus aureus was 90.3%. The moving distance of the nonwoven fabric by the cantilever method was 12.6 cm. Table 2 shows the evaluation results.

Comparative Example 2 Under the same conditions as in Comparative Example 1, the alkali metal salt in Beloasis was replaced with silver ions. Next, using these water-absorbing fibers, a nonwoven fabric absorbent having the composition shown in Table 1 was used for a normal card,
After performing needle punching, it was prepared by performing a heat treatment at 140 ° C. for 10 minutes. The sterilization rate of the prepared nonwoven fabric absorbent against Staphylococcus aureus was 91.7%.
The movement distance of the nonwoven fabric by the cantilever method is 14.
6 cm. Table 2 shows the evaluation results.

[0034]

[Table 1]

[0035]

[Table 2]

Claims (5)

(57) [Claims] 1. A method for producing a water-absorbing fiber comprising a polymer containing a carboxyl group and a metal salt thereof, wherein a part of the metal salt contains an antibacterial metal ion, and the antibacterial metal ion in 1-propanol. A method for producing a water-absorbent fiber, comprising subjecting a water-exchange fiber to an exchange reaction. 2. The method for producing a water-absorbent fiber according to claim 1, wherein the concentration of the antibacterial metal ion in the water-absorbent fiber is 10 ppm or more. 3. The method for producing a water-absorbing fiber according to claim 1, wherein the antibacterial metal ion contains at least one metal ion of silver, copper, and zinc. 4. The method for producing a water-absorbing fiber according to claim 1, wherein the water-absorbing fiber has a water absorption of 10 g / g or more. 5. A non-woven fabric absorbent containing 5 to 50% by weight of the water-absorbing fiber according to claim 1.