JPH03213546A - Water absorptive sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a water-absorbing sheet. More specifically, it has a high water absorption rate, water diffusivity, little rewetting, has a smooth surface, is washable, and is made of a fiber structure that retains its shape and is strong. Regarding the seat.

[Conventional technology]

Conventionally, water-absorbing sheets include those in which a water-absorbing resin that does not retain its shape is sandwiched between tissues, sheets fixed on a nonwoven fabric, and sheets rolled into a film. Due to the characteristics of the water-absorbing resin, these materials have a problem in that when they absorb water, their surfaces become sticky, making them uncomfortable when in direct contact with human skin. Furthermore, once these water-absorbing sheets absorb water, they swell and have the disadvantage that they cannot be used repeatedly, cannot be washed, and rewet.

On the other hand, a method in which the surface layer is made of hydrophobic fibers and the back layer is made of hydrophilic fibers (Japanese Unexamined Patent Publication No. 62-79005;
No. 9-139102), but these have the disadvantage that not only the water absorption rate of the surface layer is poor, but also water may remain on the surface layer.

As described above, conventional water absorbent sheets have a high water absorption rate, water diffusion properties, little rewetting, can be washed with a smooth surface, and have shape retention and strength. Some did not exist.

[Problem to be solved by the invention]

The present invention has a water absorption rate that is unachievable with conventional technology, has high water absorption rate, water dispersibility, little rewetting, has a smooth surface, is washable, has shape retention, and has strong water absorption rate. The purpose is to provide a dry water absorbent sheet.

[Means to solve the problem]

An object of the present invention is to provide a fibrous structure in which there are parts with a high density of fibers and parts with a low density of fibers in the thickness direction, and where the part with a low density of fibers exists on at least one side of the fibrous structure. This is achieved using a water-absorbing sheet with special features.

In the water-absorbing sheet of the present invention, it is necessary that the fiber structure has a portion where the fiber density is high and a portion where the fiber density is low in the thickness direction.

As a result, when water is absorbed, the water moves from areas of low density to areas of high density by capillary action, making the areas of low density feel dry.

Note that whether water is absorbed from low-density areas or high-density areas, as time passes, water moves to high-density areas, and low-density areas become dry.

Now, there are various methods for making a fiber structure having the above structure, but first, the fibers are made into a sheet-like material by a method such as needle punching or paper making. This is then heat-shrinked from one side at a temperature that can shrink the fibers.

At this point, as shown in FIG. 1, a fibrous structure is obtained in which there are regions with high fiber density and regions with low fiber density in the thickness direction.

However, if the overall density is low, if you increase the overall density by pressing or other methods at a temperature that does not cause fiber shrinkage, effective capillary action will be obtained when water is absorbed, and diffusion will occur. It is desirable that a water absorption sheet with high speed can be obtained.

Another method for obtaining a fibrous structure in which there are areas with high and low fiber density in the thickness direction is to laminate sheet-like materials with different densities, for example, sheet-like materials made of fibers with different fiber diameters. , two-dollar punching, columnar flow, partial adhesion or sewing to the extent that water movement cannot be prevented, and the fibers are combined to form a single fiber structure.

In addition, another method is to stack a sheet material mixed with fibers with a high heat shrinkage rate and a sheet material without mixed fibers, combine them into a single sheet, apply heat, and shrink one side. There is a way to obtain the structure shown above.

However, there are many other methods for obtaining the above structure, and the method is not limited to the above.

When the obtained fiber structure, which has areas with high fiber density and areas with low fiber density in the thickness direction, is allowed to absorb water from one side, water gathers in the higher density area, and the lower density area becomes dry. , a water-absorbing sheet that is difficult to get wet and has a smooth feel can be obtained.

Note that the extent to which water moves, that is, the degree of concentration of water, depends on the degree of density gradient of the fiber structure.

For example, if a high-density part is made so dense that it becomes a semi-film, and a low-density part is left fluffed, water will more efficiently concentrate in the semi-film.

In addition, if fibers with a crisp feel, such as irregular cross-section fibers, are used in the low-density areas, and fibers that easily absorb water, such as porous fibers, are used in the high-density areas, the low-density areas will have a dry feel. is desirable. Depending on the fibers used in this way, fibrous structures with different textures can be obtained.

Moreover, in the inside of the fiber structure in the present invention, for example, a second
As shown in the figure, when highly oriented materials such as textiles are laminated, water runs along the fibers, increasing water diffusivity in the plane direction, and as a result, the overall water absorption rate increases. , it is difficult to get wet again, which is preferable.

In addition, as shown in Figure 3, if a resin film or the like is laminated from the outside to the higher-density side, water will flow around the interface between the fiber structure and the film in the plane direction when water is absorbed. This is preferable because the water absorption rate and diffusion rate are further increased, making it difficult to get back wet. Additionally, in this case, there is an advantage that even if a large amount of water is absorbed, the water does not drip off.

Next, in the water-absorbing sheet of the present invention, it is necessary that a portion with a low density of fibers exists on at least one side of the fiber structure.

As a result, when water is absorbed, the water moves from areas of low density to areas of high density by capillary action, making the areas of low density feel dry.

Such a fiber structure may have a low density area on one side of the fiber structure as shown in Figures 1, 2, and 3, or a low density area as shown in Figure 4. However, examples include those that exist on both sides of the fibrous structure, sandwiching the high-density part that exists in the center. If the fiber structure has low density areas on both sides, water will concentrate in the center and both surfaces will feel dry. To create such a structure, there are two methods: inserting fibers with a high heat shrinkage rate in the center, stacking high-density sheets with low-density sheets, sewing, needle bunching, columnar There are methods of joining and integrating the parts using methods such as partial adhesion within the range where flow and movement of water cannot be prevented. Further, as described above, it is preferable to insert a highly oriented material in the fiber direction, such as a woven fabric, in the central part, since this increases the diffusibility of water in the surface direction.

The fiber structures in the present invention include nonwoven fabrics, knitted fabrics,
Examples include filter paper.

In addition, the type of fibers constituting the fiber structure is not limited in any way, but acrylic fibers or fibers with equivalent water affinity (polyester fibers, polyamide fibers, etc.) may be treated with resin processing, graft processing, etc. It is preferable to use a water-absorbing sheet with a high water-absorbing rate, good water-diffusing property, hard to wet back, and a smooth feel.

In addition, by using fibers with antibacterial and deodorizing functions, it is possible to maintain a clean,
A water-absorbing sheet can be obtained, which is preferable.

As described above, the water-absorbing sheet of the present invention has a high water-absorbing rate, good water-diffusing properties, and little rewetting (which was not possible in the past), has a smooth surface, is washable, and retains its shape. This is a water-absorbing sheet made of a fibrous structure that is durable and strong.Also, since the absorbed water is diffused over a wide area by capillary action, it is characterized by a high drying rate.

Therefore, the water-absorbing sheet of the present invention exhibits effects in various uses. For example, when the water-absorbing sheet of the present invention is used as a bath mat, a bath mat that does not get wet even after being used by a person and has a dry surface that feels comfortable can be obtained. This can be applied to various mats such as kitchen mats, toilet mats, entrance mats, etc. It can also be used as a water-absorbing sheet inside a refrigerator. It is also effective as a dehydrating towel after washing sweaters such as wool. In this case, either put the sweater between the absorbent sheets and press it with your hands to dehydrate it, or wrap or fold the sweater between the absorbent sheets and run it in a centrifugal dehydrator. Dehydrating sweaters is convenient because it allows sufficient dehydration without losing its shape.

Also, when used as an inner layer for boots for water work, snowy areas, dual use, etc., it feels dry and comfortable even if a little water gets in it. Similarly, it is effective as an inner material for various types of shoes such as sports shoes, and as an insole. You can also make slippers using this sheet to create water-absorbing slippers that can be completely washed.

It can also be used as part of sports clothing for Kendo and other sports, sweat vests, sweat pads, sweat bands, sweat hair bands, and hats.

Also, if it is used as a sheet for infants to play on, it is convenient in case water is spilled. Also,
This seat is good because it prevents infants from slipping when walking on it. It can also be used as a sheet for infants to eat, a sheet to put on when changing diapers, or a sheet for taking a bath. It can also be used as a bedwetting sheet by placing it on top of a futon. It can also be used as a diaper. It can also be used for diaper covers, bibs, arm covers, shoe covers, and some infant clothing.

In addition, when used as a car trunk seat, even if something leaks into the trunk, the water will be quickly absorbed and dispersed, so the water will not flow and stain the car. Because you won't get other luggage wet,
It's convenient. Also, when used as a car mat, it absorbs water from wet shoes, umbrellas, luggage, etc., and does not get wet again, so your shoes won't get dirty and your car won't get dirty either. Even if you sit in a car seat with wet clothes on a rainy day or after doing marine sports, the car will not get dirty and the person will be comfortable.

It is also suitable as a sheet for preventing water leakage during cargo transportation on aircraft. Water will not spread to other items.

It is also suitable for transporting various kinds of cargo such as trucks, freight trains, ships, etc., especially for transporting fruits and vegetables. If you place this sheet on the top surface of an uneven shelf board, it will be able to handle a fairly large amount of water.

It can also be used by laying it on the floor of the corner of the elevator as a sheet to easily remove water accumulated on the floor of the corner of the elevator. This sheet is non-slip, so it is preferred from a safety standpoint.

It is also suitable as a mat for washing dishes after washing.

It is also suitable as a commercial kitchen mat or a water-permeable mat on rainy days.

It is also suitable for absorbing water from cold heat exchangers, such as those used in air conditioners.

In civil engineering and construction, it is also effective as a water drainer during concrete construction. It is also effective as a building material to prevent condensation. Alternatively, it can be conveniently placed under windows where condensation tends to occur, under toilet water tanks, etc. to prevent discoloration or damage to houses.

It can also be used as various water supply rollers, ink water supply, cloths, and wipers.

It is also suitable for coasters, placemats, etc.

It can also be used as a soap holder and a cat's toilet.

Hereinafter, the present invention will be explained in detail using Examples, but the present invention is not limited to these Examples or the drawings.

(Example) Using acrylic fibers (3d, 51+n+n length), needle punch a non-woven fabric (300g basis weight), 50cm width
I made a 5m length. A 50 cm x 2 m portion of this was heat-shrinked on one side using a single-sided heat roller (110°C) to produce Example 1 of the present invention.

Next, using acrylic fibers (3d, body length 51), a polyester fabric was inserted as a base fabric, and a nonwoven fabric (300g basis weight) was made with a needle punch, 50cm wide and 5m long. Transfer this to a size of 50cm x 1m using a single-sided heat roller (1
Example 2 of the present invention having the structure shown in FIG. 2 was produced by heat shrinking on one side at 10°C.

Next, 50 cm x 1 m of the same needle-punched nonwoven fabric (with woven fabric) as in Example 2 was heated on one side using a heated roller (210°C).
Example 3 of the present invention was produced by heat-shrinking one side.

Next, a polyester film was adhered to the heat-shrinking side of Example 1 using a single-sided heated roller, thereby producing Example 4 of the present invention having a structure as shown in FIG. 3.

Next, a needle made by mixing 90% of the acrylic fiber (3d x 51mm) and 10% of heat-shrinkable acrylic fiber (3d x 38mm) between two sheets of needle-punched nonwoven fabric (100g basis weight) of acrylic fiber (3d x 51nun) was placed. A punched nonwoven fabric was sandwiched between the pieces, and then a needle punch was applied to make a sheet. This was placed in a dryer at 108° C. for 1 minute to produce Example 5 of the present invention having a structure as shown in FIG.

On the other hand, as Comparative Examples, Comparative Examples 1 to 5 were obtained by omitting the step of heat shrinking, corresponding to Examples 1 to 5, respectively.

The rewetting properties and diffusion rates in the surface direction of Examples 1 to 5 and Comparative Examples 1 to 5, which are the products of the present invention, are shown below.

First, to measure the rewetting property, each sample was cut into 20 cm square pieces, placed on a glass plate, 3 ml of water was dropped from one side, and after a certain period of time, a 20 cm square filter paper and a glass plate were placed on the sample, and a 2 kg weight was placed on the sample. was placed on the filter paper for 10 seconds, and the weight change of the filter paper was measured. The results are shown in Table 1.

Next, the diffusion rate in one plane direction was determined by cutting each sample into 20c+n squares, placing them on a glass plate, and pouring 3 ml of ink water from one side.
After dropping the ink, the diameter of the spread of the ink water after a certain period of time was measured from both sides. The results are shown in Table 2.

4. Wetting property (Table 1) Unit: Table 1 From Table 1, it can be seen that Examples 1 to 5 of the present invention had a smaller amount of rewetting than the corresponding Comparative Examples 1 to 5.

In addition, from Table 2, Examples 1 to 5 correspond to Comparative Example 1.
It can be seen that the diffusion rate in the plane direction is higher than that of Samples 5 to 5.

Furthermore, when touched with the hand, Examples 1 to 5 felt dryer and smoother than the comparative example.

〔Effect of the invention〕

As described above, the product of the present invention is a quick-drying, water-absorbing sheet that has a high water absorption rate, high water diffusivity, little rewetting, has a smooth surface, and has shape retention and strength.
It can be used in a wide range of applications.

[Brief explanation of drawings]

1 to 4 show cross-sectional views of the water-absorbing sheet of the present invention. 1-1111 Fibrous structure with high and low fiber density in the thickness direction 2-Highly oriented material 7 Resin film ■ Figure 1 Coarse Figure 3 Figure 1 Complete Figure 4

Claims (1)

[Claims] A water-absorbing sheet comprising a fibrous structure in which a portion with a high density of fibers and a portion with a low density of fibers exist in the thickness direction, and the portion with a low density of fibers exists on at least one side of the fibrous structure. .