JP3457920B2 - Method for preventing dropping of superabsorbent resin in sheet superabsorbent composite - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a sheet-shaped superabsorbent composite having a sheet-shaped substrate provided with an absorbent layer containing superabsorbent resin particles on the surface thereof. The present invention relates to a falling prevention method for preventing falling of water-absorbent resin particles.

[0002]

2. Description of the Related Art On the surface of a sheet-like base material such as nonwoven fabric,
There is known a sheet-shaped superabsorbent composite in which superabsorbent resin particles are supported as a layer. Super Absorbent Resin (Super Absorb
ent Polymer, sometimes referred to as “SAP” hereinafter) is generally a partially cross-linked water-swellable polymer such as calgikin methylcellulose, polyacrylic acid and its salts, polyethylene oxide and polyacrylamide.
Alternatively, it is a copolymer of isobutylene and maleic acid or the like. Also included are biodegradable amino acid crosslinked products of polyaspartic acid, or superabsorbent resins of microbial origin, which are culture products from Alcaligenes Latus. SAP
As products, those having various forms such as particles, granules, films, and non-woven fabrics have been developed, and all of them can be used in the present invention, and among them, desirable ones in the present invention are: Granules, granules, flakes, and pellets that can be uniformly dispersed in a dispersion medium are collectively referred to as "particles" here.

[0003] Such SAP particles in a dry state have almost no adhesive property themselves, and therefore, to be supported as a layer on the surface of a sheet-like substrate such as a nonwoven fabric,
Between the SAP particles as well as the S
It is necessary to bond the AP particles and the sheet-shaped substrate. The present inventors have used sheet-like superabsorbent composites having a structure in which superabsorbent resin particles are mutually bonded by microfibrils by using hydratable microfibrils obtained from cellulose or cellulose derivatives. Was previously proposed (for example, Japanese Patent No. 2960927).
No.).

[0004]

However, the SAP
Even when using microfibrils with extremely excellent performance as a binder for particles, SAP particles are completely prevented from falling off from the absorbent layer due to bending and surface friction during handling of the sheet-shaped superabsorbent composite. Is difficult to do.

As aspects of the SAP particles falling off, in addition to the manufacturing process of the high-absorbent sheet, processing steps such as forming slits in the high-absorbent sheet, and the absorbent body such as a disposable diaper for the high-absorbent sheet. Examples include an assembling process for incorporating the product. Specifically, the superabsorbent sheet has microfibrils and SA on the surface of the sheet-shaped substrate.
It is manufactured through a manufacturing process in which a slurry-like coating liquid containing P particles is applied and dried to form an absorber layer, and the absorber layer is passed through an accumulator and wound by a winder. During this process, in the drying process, accumulator and winder, the SAP may be bent, contact with other objects, friction between the absorbent layers, etc.
Dropping of particles occurs.

Such bending and contact are repeated in the process of forming slits, chopping, or combining with other elements in order to incorporate the completed high-absorbency sheet into the absorbent product, and each time, the bending and contact are repeated. The SAP particles fall off from the absorber layer. The drop of SAP particles is simply the SAP in the product.
Not only does the amount of particles decrease, but the work environment is deteriorated due to the scattering of fine powder. Further, in the completed sheet-shaped superabsorbent composite, the SAP particles sticking to the hand or spilling off when checking the appearance, feel, etc. of the sheet are negative in terms of product evaluation.

[0007]

Means for Solving the Problems The present inventors have found that a sheet-like superabsorbent composite provided with an absorber layer containing SAP particles is
In a dry atmosphere, it shows stiff and stiff properties,
When the content of SAP particles is high, the phenomenon of cracking is likely to occur, but it was found that there is a phenomenon of high flexibility and slight tackiness in an atmosphere of high humidity, and the present invention was completed. It was

That is, according to the present invention, the sheet-shaped superabsorbent composite is provided with S in the above-mentioned situation in which the fine particles are significantly removed.
By handling the AP particles while absorbing a certain amount of water, it becomes possible to effectively prevent the SAP particles from falling off.

According to the present invention, an absorbent material comprising a sheet-like substrate and superabsorbent resin particles provided on the surface of the sheet-like substrate, which are bonded to each other and to the sheet-like substrate, is a main component. Sheet-like superabsorbent composite with body layer
Processing, during processing, from the sheet-shaped highly absorbent composite <br/>, a method of the super absorbent polymer particles can be prevented from falling off, processing the sheet highly absorbent composite Before
The sheet-like high water absorption during the process of manufacturing the absorbent product.
When the water content is increased by contacting the super absorbent polymer particles of the hydrophilic composite with water ,
There is provided a method for preventing falling-off of superabsorbent resin particles in a sheet-shaped superabsorbent composite, characterized by maintaining a water content within a range of 15 to 50% by weight .

The water content of the superabsorbent resin particles is about 5 to 10% by weight under normal temperature and humidity conditions. However, by increasing the water content by an appropriate means, they are bonded by microfibrils. The highly water-absorbent resin particles are stably held at that position, and the dropout from the absorber layer is significantly reduced. The preferred water content is 10% by weight or more, but the most preferred range is 15 to 50% by weight.

The simplest means for keeping the superabsorbent resin particles in a water-containing state is to spray water on the absorbent layer of the sheet-shaped superabsorbent composite, while avoiding excessive water absorption.
A means for achieving an appropriate increase in water content is to bring the sheet-shaped superabsorbent composite into contact with water in mist form. Mist is an expression that shows the state of fine mist-like water,
For example, means such as using a mist generator using ultrasonic waves or passing through a steam zone using saturated steam is adopted.

Alternatively, if the space for processing and processing the sheet-shaped super absorbent composite is a small room, it is possible to maintain the super absorbent polymer particles in a water-containing state by increasing the humidity in the room. is there.

The reason why such a water content prevents the super absorbent polymer particles from falling off is that the water content acts as a plasticizer for the microfibrils and the super absorbent polymer due to the water content. Secondly, it is considered that the second reason is that the occurrence of cracks is prevented and the affinity between the super absorbent polymer and the substrate is improved.

Upon addition of such water, an antibacterial agent, a fungicide or a fragrance which coexists in the water and dissolves in water or uniformly disperses in water is added to the sheet-shaped super absorbent composite. It is possible to adsorb and fix antibacterial and antifungal properties, or perfume ingredients. Examples of the antibacterial component products include antibacterial cationic activators, quaternary ammonium salts, and chitosan salts. As the fragrance component, any substance such as a perfume component, an essential oil component, a deodorant agent, etc., which is uniformly dissolved and dispersed in water and is highly safe for the skin, may be used.

As an example of the use of the deodorant, for example, a collecting component of green tea containing a large amount of polyphenols may be added at a pH of 5 to 6.
It is also possible to impart a deodorizing function by adding to the sheet-shaped super absorbent composite as a weakly acidic aqueous solution of about 20% by spray spraying, absorbing and absorbing.

The added antibacterial, fragrance component, deodorant, etc. are stably occluded in the superabsorbent resin together with water. When these active ingredients added are used in diapers, napkins, etc., they are released to the outside of SAP by absorption of the discharged liquid into SAP, and exert an active function.

[0017]

Falling prevention method of the embodiment of the invention] SAP particles that put the sheet highly absorbent composite <br/> of the present invention, in some aspects may occur falling off during handling, a predetermined amount of water to the SAP particles It is carried out by including it. Regarding the amount of water absorbed by the SAP particles, according to a number of experiments conducted by the present inventors, a remarkable effect was confirmed when it was preferably 15% or more, more preferably 20 to 50% by weight of the SAP particles. Was done.

SAP used for the purpose of absorbing water
The intention of the particles to absorb water is to reduce the overall absorption capacity, which should be avoided in common sense, but the water absorption capacity of SAP particles is several hundred times their own weight. Even if 20% to 50% of water is absorbed in advance, it is in a negligible range from the viewpoint of the absorption capacity as a whole. However, if the water content exceeds 50%, the adhesiveness will increase and it will cause troubles such as winding around a roll etc.
The following is desirable.

The superabsorbent sheet targeted by the present invention is produced by applying a slurry-like coating solution to a sheet-like base material such as a nonwoven fabric and drying it. There are various kinds of means for applying the coating liquid, but when the coating liquid has relatively low fluidity, a contact type applicator is used. The SAP sheet obtained by combining with the sheet-shaped substrate is dried and wound to produce a sheet-shaped super absorbent composite (step 1). The obtained composite is subjected to processing steps such as slit processing, laminating processing, hot melt processing, etc., and is used as a winding roll (step 2). The obtained roll-shaped product is sent to a manufacturer of diapers, napkins, etc. and processed as an absorber portion of the absorber product (step 3).

The water addition according to the present invention can be considered in any of the steps 1 to 3, but the present invention is premised on the final processing step (step 3). When it is added in (Step 1), it is easily performed by adjusting the moisture content during drying, and the effect is shown in (Step 2) and (Step 3) after that, which is seemingly rational. Since the product obtained in step 1) is stored in a roll state in a pressure-bonded state for a relatively long time, due to the tackiness of SAP generated by water, the so-called blocking phenomenon occurs by bonding and adhering to the back surface of the base material that the SAP coated surface contacts. It may cause troubles such as raising and rewinding. In addition, when stored for a long time in a high temperature period in the summer with water content,
It also causes mold. Therefore, it is desirable that (Step 1) and (Step 2) be performed in a dry state as much as possible, and that water be added in (Step 3).

Such a sheet-shaped super absorbent composite is accompanied by falling of SAP particles under normal environmental conditions (hereinafter referred to as "dry") due to bending and friction during handling.
The stability tester manufactured by the present inventor was used to test how much the dropout occurred.

The structure of the stability tester is shown in FIG. Using this stability tester, the stability of SAP during drying was measured under the following conditions. In FIG. 1, reference numeral 1 is a motor, 2 is a sample of a highly absorbent sheet to be evaluated, 3 is a drive belt, 4 is a drive roller, 5 is a tape, 6 is a coating liquid application surface of a sample, 7 is its back surface, 8 Is a tension roller.

1. Preparation of sample 1) Sample size Cut into 10 cm width x 80 cm length as a basic size.
The width is a repeating unit such as a stripe pattern depending on the sample. The width is about 10-30 cm. 2) Predrying In order to keep the water content constant during evaluation, predrying is performed until the water content becomes 10% by weight or less. However, in order to prevent deterioration of the sample, the drying temperature is set to 60 ° C or lower. 3) At least 1 under the temperature and humidity conditions that the seasoning water content becomes 10% by weight.
Leave for 2 hours. Open the coated surface in a constant temperature and humidity chamber or container.

2. Sticking property evaluation of SAP by tester 1) Sample weight measurement (using an electronic balance with a sensitivity of 1 mg) Subtract the substrate weight from the sample weight to calculate the amount of SAP applied to Sample 2 (W ₀ ). 2) Mount sample 2 on the tester. With the coated surface 6 on the outside, the base material surfaces at both ends of the sample 2 are connected with an adhesive tape (FIG. 1 (d)). 3) Apply a load with the tension roller 8. The load is 1 kg
/ 10 cm width. 4) Start up In order to collect the lost SAP, put black paper on the lower side of the sample running place in advance and switch on the motor 1. The traveling speed is set to 30 m / min. 5) Check the amount of SAP lost after 1 minute. FIG. 2 is a diagram showing the relationship between the traveling time and the amount of drop. As the amount of SAP with insufficient adhesion (zone A), SAP for 1 minute after startup
Check the dropout amount (W ₁ ). 6) Check the amount of dropped SAP 4 minutes after restart. As the amount of SAP lost over time due to bending friction (B zone), the amount of SAP lost for 4 minutes after restart is examined (W ₂ 62). 7) Calculation of the amount of SAP lost The amount of SAP dropped for one minute after startup (the amount of SAP that does not adhere sufficiently)
= (W ₁ / W ₀ ) × 100 Dropping amount for 5 minutes after startup (total SAP amount dropped) = [(W
₁ + W ₂ ) / W ₀ ] × 100

Under the above measurement conditions, a large number of samples having the same constitution were prepared, and the amount of shed was measured under the same conditions except that the water content of the SAP particles of each sample was changed, and the obtained results are shown in the graph of FIG. Shown in. From this result, there is no significant difference in the amount of SAP particles up to 15% water content, but when it reaches 20%, the amount of removal falls sharply, and when it exceeds 30%, there is almost no loss. I understand.

[0026]

As described above, according to the present invention,
It is possible to effectively prevent the superabsorbent resin particles from being inadvertently dropped off during the treatment and processing of the sheet-shaped superabsorbent resin composite having the absorbent layer containing the superabsorbent resin particles. Therefore, it is possible to maintain stable performance of the superabsorbent composite without causing deterioration of the absorption performance due to a decrease in the content of the superabsorbent polymer particles. In addition, it is possible to prevent the deterioration of the working environment due to the scattering of the fine superabsorbent resin particles that have fallen off.

[Brief description of drawings]

FIG. 1 shows a configuration of a stability tester, (a) is a front view,
(B) is a side view, (c) is a plan view of the sample, and (d) is a perspective view of the sample.

FIG. 2 is a graph showing the relationship between the running time of a sample in a dry state and the amount of SAP removed, measured using the test apparatus shown in FIG.

FIG. 3 is an SA measured by using the test apparatus shown in FIG.
The graph which shows the relationship between the running time of the sample from which the water content of P particle | grains differ, and the falling amount of SAP.

[Explanation of symbols]

1 motor 2 High-absorbency sheet samples to be evaluated 3 drive belt 4 drive roller 5 tapes 6 Application liquid application surface 7 Back side 8 tension roller

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D06M 11/05 A61F 13/15

Claims (7)

(57) [Claims] 1. A sheet-shaped substrate, and an absorber layer, which is provided on the surface of the sheet-based substrate and has superabsorbent resin particles bonded to the sheet-shaped substrate as a main component to each other by microfibrils. Treatment and processing of sheet-shaped super absorbent composites
During the the sheet highly absorbent composite, a method of the super absorbent polymer particles can be prevented from falling off,
It said processing the sheet highly absorbent composite absorbent product
In the step of producing the above-mentioned sheet-like super absorbent polymer particles , water is brought into contact with the super absorbent polymer particles of the sheet-shaped super absorbent composite so that the water content is 15 to 50 weight.
Characterized by maintaining the water content in the range of amount% ,
A method for preventing falling-off of superabsorbent resin particles in a sheet-shaped superabsorbent composite. 2. An ultrasonic mist generator as added water
By contacting the mist-like water of
The method according to claim 1, wherein the fat particles are maintained in a water-containing state . 3. Mist from saturated steam as added water
The highly water-absorbent resin particles by contacting with water-like water
The method according to claim 1, which is maintained in a water-containing state . 4. Dissolvable in water or stably dispersed in water
Anti-bacterial agent is added in the presence of added mist-like water.
The method according to claim 2 or 3, wherein 5. Dissolved in water or stably dispersed in water
The fragrance is added together with the mist-like water.
The method according to claim 2 or 3, characterized in that 6. The method according to claim 2 or 3 is dissolved in water, or coexist with mist moisture adding a deodorant stably dispersed in water, characterized in that added. 7. The sheet-shaped superabsorbent composite is treated and added.
High water absorption by increasing the humidity of the working space
The method according to claim 1 , wherein the resin particles are maintained in a water-containing state .