JPH11279914A - Flame-retardant absorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retardant absorbent containing a flame-retardant fiber and a water-absorbing flame-retardant fiber in specific state, keeping excellent flame-retardancy without lowering the liquid absorbing performance and suitable e.g. for the ink-absorbent of ink-jet printer. SOLUTION: This flame-retardant absorbent contains a flame-retardant fiber and a water-absorbing flame-retardant fiber (the water-absorbency is preferably >=10 g/g) in a state to form a nonwoven fabric with the flame-retardant fiber and the water-absorbing flame-retardant fiber by needle-punching after blending and carding. Preferably, the flame-retardant fiber has an LOI value of >=25 and its blending ratio is 5-95 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant absorber made of a nonwoven fabric, and more particularly to a flame-retardant absorber suitably used for an ink absorber of an ink jet printer.

[0002]

2. Description of the Related Art Conventionally, as an ink absorber for an ink jet printer or the like, a non-woven fabric obtained by mixing a water-absorbing resin or a water-absorbing fiber with a flame-retardant fiber has been widely used. For example, Japanese Patent Application Laid-Open No. 8-31755 describes an absorber obtained by mixing a water-absorbing fiber and a flame-retardant fiber with a non-woven fabric to impart both liquid-absorbing properties and flame-retarding properties. However, such an absorbent has a disadvantage that the portion of the water-absorbent fiber does not have flame retardancy, so that a candle formation phenomenon occurs at the time of combustion, and the overall flame retardant of the absorbent is insufficient. In particular, for ink absorbers for ink jet printers, V0 of the flame resistance standard UL94 vertical test
These flame retardants are required to pass these tests, and therefore, these improvements are required.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an absorbent having excellent flame retardancy without impairing the liquid absorbing property.

[0004]

Means for Solving the Problems The present inventors have studied the preparation of the material constituting the absorber and the manufacturing method, and have completed the present invention. That is, an absorbent body containing a flame-retardant fiber and a water-absorbing flame-retardant fiber, characterized in that the flame-retardant fiber and the water-absorbing flame-retardant fiber are blended, carded, and then obtained by needle punching. It is an absorber.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The flame-retardant fibers used in the present invention are not particularly limited. For example, known flame-retardant fibers such as a type obtained by copolymerizing a flame-retardant polymer such as modacrylic fiber or a type obtained by adding a flame retardant to a polymer can be used. Also, a mixture of these may be used.

It is preferable that these flame-retardant fibers have an LOI value of 25 or more and a mixing ratio of 5 to 95% by weight. It is preferable if it is in these ranges, since sufficient flame retardancy as an absorber can be obtained.

The water-absorbing and flame-retardant fiber used in the present invention is not particularly limited. The polymer consists of a monomer that provides a carboxylic acid group and a monomer that contains a hydroxyl group that reacts with the carboxylic acid group to form an ester crosslink. Acrylic acid and its water-soluble salts are used as the monomer for providing a carboxylic acid group.

Examples of the monomer containing a hydroxyl group include vinyl alcohol, allyl alcohol, epoxide-substituted vinyl monomers, and hydroxyalkyl esters of vinyl carboxylic acid monomers. Specific compound names include hydroxyethyl methacrylate,
Examples include hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glyceryl monomethacrylate, and glyceryl monoacrylate. Each of these monomers may be used in plural types.

[0009] The monomer having a hydroxyl group is preferably contained in an amount of 0.5% by weight or more in an equivalent amount or less with free acrylic acid. When the content is 0.5% by weight or more, the crosslinking proceeds sufficiently and the strength of the fiber is maintained, so that the operability during the production of the nonwoven fabric is good.

In addition to the above monomers, other vinyl monomers such as vinyl acetate and acrylonitrile may be used to impart plasticity.

The method for polymerizing the above monomers is not particularly limited. If the monomer composition is water-soluble, aqueous polymerization is preferable, and a commonly used sodium persulfate or the like may be used as the polymerization initiator.

In the spinning method for producing the water-absorbing flame-retardant fiber used in the present invention from the above-mentioned polymer, dry spinning is preferred in the case of aqueous polymerization. In the case of wet spinning, water cannot be used as a coagulant, so that an organic solvent system must be used.

After the dry spinning, the moisture content of the water-absorbing flame-retardant fiber is generally adjusted to 8 to 25% based on the dry weight of the fiber, and stretching, crimping, cutting and the like are appropriately performed. If the moisture content is less than 8%, the strength of the fiber becomes insufficient and the fiber becomes brittle, which is inappropriate.

The water-absorbing flame-retardant fiber thus taken out undergoes a heat treatment to crosslink the polymer chain in order to render the polymer insoluble. First, these fibers are further dried to a moisture content of 0-10%, preferably 4-8%. Drying is
It is carried out at a temperature below 100 ° C. to avoid damage due to the formation of heated steam bubbles in the fiber structure. This is generally done by passing the fibers through a furnace at a temperature above 50 ° C, for example 60-90 ° C.

Next, in the cross-linking step, heating is performed to cause sufficient cross-linking of the polymer chains to render the water-soluble polymer insoluble. The temperature at this time is generally 125 to 2
It is in the range of 50 ° C. When an ester crosslink is formed by the reaction of the carboxylic acid and the hydroxyl group, the preferred temperature for the crosslink is at least 150 ° C or 160 ° C;
And it is preferably 225 ° C or lower. If the temperature is lower than 150 ° C., the progress of crosslinking is slowed, and the gel strength may not be obtained as a fiber at a predetermined water absorption. 225 ° C
If the temperature is higher than the above, the polymer may be deteriorated during the crosslinking step due to the high temperature.

The time during which the crosslinking step is carried out is generally from 2 minutes to
It is in the range of 2 hours, preferably between 5 and 15 minutes. If the time is less than 2 minutes, there is a possibility that the gel strength at the time of predetermined water absorption may not be obtained as a fiber due to insufficient crosslinking in the polymer. On the other hand, when the time is 2 hours or more, cross-linking in the polymer increases, and the fiber may not have a predetermined water absorption.

These water-absorbing flame-retardant fibers have an LOI value of 25.
It is preferable that it is above. When it is 25 or more, when the absorbent is used, the portion of the water-absorbing flame-retardant fiber also has the flame retardancy, so that the burning of the candle does not occur, and the flame retardancy of the entire absorbent body is improved, which is preferable.

Further, these water-absorbing flame-retardant fibers have a water absorption of 1
It is preferably at least 0 g / g. When the content is 10 g / g or more, sufficient liquid absorbency and liquid absorbability as an absorber can be obtained, which is preferable.

As an example of the above-mentioned water-absorbing fiber, there is "Bell Oasis" (trade name) manufactured by Technical Absorbent and imported and sold by Kanebo Synthetic Co., Ltd.

It is also possible to mix other types of fibers as long as the flame retardancy, which passes V0 of the UL94 vertical test, is not impaired.

In the method for producing an absorbent comprising fibers, it is necessary to perform needle punching after carding. That is, specifically, the raw material cotton is opened and mixed, then the card is passed through a card to produce a web, and further needle punched to produce a nonwoven fabric absorbent. Without the needle punching step, the fibers in the absorber are weakly entangled with each other, and the swelling of the water-absorbing fibers during liquid absorption cannot be suppressed.

[0022]

According to the present invention, there is provided an absorbent body having excellent flame retardancy without impairing the liquid absorbing property.

[0023]

[Example] (Method of measuring and evaluating liquid absorbency) A sample was cut out to 10 cm x 10 cm, immersed sufficiently in a liquid, and allowed to stand on a 40-mesh wire net so that no drops would fall. After the weight is measured, 10cm x 1
The liquid absorption amount per 0 cm was determined. The evaluation was ◎ when the liquid absorption was 80 g or more, ○ when 60 g or more and less than 80 g, and Δ when less than 60 g.

(Measurement Method of Dropping and Evaluation Method) In the above-described measurement of the liquid absorbency, the time during which the liquid was not completely dropped after the liquid-absorbent sample was allowed to stand on the wire mesh was measured. Evaluation: less than 3 minutes ◎, 3 minutes or more and less than 10 minutes ○, 1
0 minutes or more were evaluated as Δ.

(Method for Measuring and Evaluating Volume Swelling Ratio Due to Liquid Absorption) In the above-described measurement of liquid absorption, the thickness before and after liquid absorption was measured, and the volume swelling ratio was calculated. Swelling ratio (%) = (thickness after liquid absorption-thickness before liquid absorption) x 100 /
Thickness before liquid absorption Evaluation: less than 10% ◎ 10% or more and less than 15% ○, 1
5% or more was evaluated as Δ.

(Method of Measuring and Evaluating Flame Retardancy) A flame retardant standard UL94 vertical test was performed. In addition, the evaluation was V0 ◎,
V1 was rated as 、, V2 as Δ, and burnt down as ×.

Example 1 Flame-retardant acrylic fiber "Lufenn" (LOI value 29), 2 denier, 51 mm, manufactured by Kanebo Gosen Co., Ltd. as a flame-retardant fiber
95% by weight, as a water-absorbing flame-retardant fiber, "Belle Oasis" manufactured by Kanebo Gosen Co., Ltd. (LOI value 42; water absorption 65)
g / g) 9 denier and 51 mm were mixed at 5% by weight, and carding, cross laying and needle punching were performed in a usual felt manufacturing process, and the thickness was 8 mm and the basis weight was 1600 g / m.
You got ² felts.

The manufactured felt was cut into 10 cm × 10 cm to prepare a test body. The liquid absorption of this test sample with respect to a commercially available ink for an ink jet printer was 80.
3 g. Dropping of the absorbed ink was completed within one minute, and the water absorption retention was good. These specimens also had good dimensional stability and a swelling ratio of less than 3%. Furthermore, the flame retardancy (flammability standard UL94)
Vertical method) had the best result of V0. Table 1 shows the results
Shown in

Example 2 Flame-retardant acrylic fiber "Lufenn" (LOI value 29), 2 denier, 51 mm, manufactured by Kanebo Gosen Co., Ltd. as a flame-retardant fiber
85% by weight, as a water-absorbing flame-retardant fiber, "Belle Oasis" manufactured by Kanebo Gosen Co., Ltd. (LOI value 42; water absorption 65
g / g) 9 denier, 5% by weight of 51 mm, rayon (LOI value: 23; water absorption: 15 g / g), 2 denier, 51
mm was mixed at 10% by weight, and carding, cross-laying, and needle punching were performed in a normal felt manufacturing process to obtain a felt having a thickness of 8 mm and a basis weight of 1600 g / m ² .

The manufactured felt was cut into 10 cm × 10 cm to prepare a test body. The liquid absorption of this test sample with respect to a commercially available ink for an ink jet printer was 82.
It was 4 g. Dropping of the absorbed ink was completed within one minute, and the water absorption retention was good. These specimens also had good dimensional stability and a swelling ratio of less than 3%. Furthermore, the flame retardancy (flammability standard UL94)
Vertical method) had the best result of V0. Table 1 shows the results
Shown in

Comparative Example 1 Flame-retardant acrylic fiber "Rufen" manufactured by Kanebo Gosen Co., Ltd.
(LOI value 29) 100% by weight of 2 denier, 51 mm, carding, cross laying, and needle punching in the usual felt manufacturing process, thickness 8 mm, basis weight 160
A felt of 0 g / m ² was obtained.

The manufactured felt was cut into 10 cm × 10 cm to prepare a test body. The liquid absorption of this test sample with respect to a commercially available ink for an ink jet printer is 50.
2 g. Dropping of the absorbed ink was completed in 15 minutes. Their swelling ratio was less than 3%. Furthermore, the flame retardancy (flame retardant standard UL94 vertical method) as the absorber was V0 good. Table 1 shows the results.

Comparative Example 2 Flame-retardant acrylic fiber "Lufen" (LOI value 29), 2 denier, 51 mm, manufactured by Kanebo Gosen Co., Ltd. as a flame-retardant fiber
95% by weight, regular rayon (LOI value: 23; water absorption: 1) manufactured by Kojin Co., Ltd. as a regular water-absorbing fiber.
5 g / g) 5% by weight of 2 denier and 51 mm were mixed and subjected to carding, cross laying and needle punching in a usual felt manufacturing process to obtain a thickness of 8 mm and a basis weight of 1600 g / g.
An m ² felt was obtained.

The manufactured felt was cut into 10 cm × 10 cm to prepare a test body. The liquid absorption of this test sample with respect to a commercially available ink for an ink jet printer was 60.
9 g. Dropping of the absorbed ink was completed in 5 minutes. Their swelling ratio was less than 3%. However, flame retardancy as an absorber (flame retardant standard UL94 vertical method)
Has been burned down by the candle phenomenon. Table 1 shows the results.

[0035]

[Table 1]

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nagayuki Numata 1-2-2 Umeda, Kita-ku, Osaka-shi Kanebo Synthetic Fibers Co., Ltd. (72) Naoki Momoi 1-2-2 Umeda, Kita-ku, Osaka-shi Kanebo Gosen Co., Ltd.

Claims (4)

[Claims] 1. An absorbent body containing a flame-retardant fiber and a water-absorbing flame-retardant fiber. Characteristic absorber. 2. The absorbent body according to claim 1, wherein said flame-retardant fiber has an LOI value of 25 or more and a mixing ratio of 5 to 95% by weight. 3. The absorbent body according to claim 1, wherein the water-absorbing flame-retardant fiber has an LOI value of 25 or more. 4. The water-absorbing flame-retardant fiber has a water absorption of 10 g /
The absorbent body according to any one of claims 1 to 3, which has a weight of at least g.