JPH0726358B2 - Water-degradable non-woven fabric - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-decomposable nonwoven fabric which has sufficient strength even in a wet state during use and is hydrolyzed when immersed in a large amount of water.

[Prior art and its problems] In conventional baby wipes, wet tissues for women's sanitary or wet tissues for defecation treatment, fibers are completely formed with a nonwoven fabric or a water-soluble binder produced by the spunbond method as a base material of the tissues. The non-woven fabric obtained by binding to the product is used, and when it is discarded in a flush toilet, for example, the product retains its original form, which may cause clogging in the sewer pipe or the function of the simple septic tank. Sometimes hindered.

Therefore, in order to temporarily make the water-soluble binder insoluble in water in a nonwoven fabric using the water-soluble binder, JP-A-54
JP-A-104963 discloses a material impregnated with a specific salt or an aqueous solution containing a predetermined concentration of salt necessary for salting out, and polyvinyl alcohol as a water-soluble binder thereof, and a predetermined water-insoluble binder. An aqueous solution of boric acid having a concentration of 3% or more is used as an aqueous solution containing salts, and an aqueous solution of sodium sulfate having a concentration of 7% or more is used as a solution for salting out polyvinyl alcohol.

However, as described above, an aqueous solution containing a specific salt or a salt having a predetermined concentration necessary for salting out is an aqueous sodium sulfate solution or an aqueous boric acid solution, which is a primary irritant to the skin, an irritant to the eye mucous membrane, an oral toxicity, etc. There is a problem in terms of safety.

Further, JP-A-59-144426 discloses a water-decomposable nonwoven fabric impregnated with an oily liquid, and as the water-decomposable nonwoven fabric, a nonwoven fabric made of cellulosic fibers or a water-soluble binder is used. A non-woven fabric that combines fibers is used,
Since the non-woven fabric is impregnated with an oily liquid, there is no breaking of hydrogen bonds between cellulosic fibers and dissolution of the water-soluble binder in the wet state, and its use strength is sufficient, and it can be used in a large amount of water. It dissolves when soaked.

However, when wiping the skin of the human body, the impregnated oily liquid adheres to the skin, causing stickiness and discomfort, and excretion from the human body is water-soluble, so the impregnated oily liquid There is a problem that it is difficult to mix with the liquid.

When the water-decomposable non-woven fabric is moistened with paper to wipe the skin of a human body, fibers are generally detached (hereinafter referred to as paper dust) and may adhere to the skin. As an example, when the toilet paper currently on the market is moistened with water and used, such a fact is confirmed.

The generation of such paper dust becomes a particularly serious problem when the above water-decomposable nonwoven fabric is used for wipes,
Further, when such a means for preventing the generation of paper dust is applied, there is a problem that the water decomposability of the non-woven fabric is lowered, and so far the technical problem has not been solved.

The present invention has been made to solve the above problems, and has sufficient strength in a wet state, and when discarded in a flush toilet, its shape is easily destroyed, resulting in a fibrous or small block. The object is to obtain a water-decomposable non-woven fabric which is dispersed in the shape of a sheet and does not generate paper dust during use.

[Means for Solving Problems] That is, the present invention provides a water-decomposable nonwoven fabric substrate in which a water-insoluble resin is partially provided on at least one surface layer of a water-decomposable nonwoven fabric substrate. The present invention relates to a water-decomposable non-woven fabric, characterized in that at least a surface layer provided with a water-insoluble resin is provided with a cut.

The term "water-decomposability" as used herein means that when it is discarded in a flush toilet or the like, the non-woven fabric easily causes clogging in the sewer pipe or is broken by running water to a size that does not impair the function of the simple septic tank. Says the nature.

[Operation] Since the water-decomposable nonwoven fabric of the present invention is partially provided with a water-insoluble resin in at least one surface layer, even if the nonwoven fabric is in a wet state, fibers do not separate from the surface layer. Is hindered. If the non-woven fabric is not partially cut, the surface of the non-woven fabric not provided with the water-insoluble resin will be easily hydrolyzed into a fibrous form when it is discarded in the flush toilet, but the water-insoluble The surface layer of the non-woven fabric provided with the resin is not hydrolyzed and may cause clogging in the sewer pipe.

Therefore, in the present invention, the water-insoluble resin of the non-woven fabric is used so that the non-woven fabric can be easily broken into blocks by mechanical external force such as water flow even when it is discarded in the flush toilet. The surface layer provided with is partially pre-cut.

Therefore, even when the non-woven fabric is provided with a water-insoluble resin on both surface layers, if the surface layer provided with the water-insoluble resin is partially pre-cut as described above, It is easily broken into blocks by mechanical external force such as water flow.

[Example] The water-decomposable non-woven fabric of the present invention can be obtained by partially providing a water-insoluble resin on at least one surface layer of the water-decomposable non-woven fabric substrate and further providing a partial cut in the water-degradable non-woven fabric substrate. To be

Examples of the water-decomposable non-woven fabric include softwood fibers such as red pine and Todomatsu, hardwood fibers such as beech and Japanese oak, as well as wood bast fibers such as Kozo, Mitsumata and Gampi, flax, hemp, jute and ramie. Leather bast fiber, leaf fiber such as mania hemp, sisal hemp, bamboo, straw,
Fiber pulp for papermaking such as monocotyledonous plant fibers such as bagasse; regenerated cellulose fibers such as viscose rayon and cupra; polyamide fibers such as nylon; polyester fibers; vinyl chloride fibers such as Devilon (registered trademark); chloride Examples thereof include vinylidene fibers, polypropylene fibers, acrylic fibers, polyvinyl alcohol fibers, and other synthetic fibers. These may be used alone or in combination of two or more. Of these, cellulosic fibers such as fiber pulp for papermaking or rayon are preferable because they are easily decomposed by microorganisms such as cellulomonas and cell vibrio bacteria.

The fiber length is preferably about 1 to 10 mm from the viewpoint of the wet strength of the product and the water decomposability when it is discarded in a washing tray, but the surface layer of the non-woven fabric provided with the water-insoluble resin has an appropriate size. The fiber length is 3 to 7 m in order to break into
Especially preferred is about m.

When a water-decomposable non-woven fabric substrate is prepared using fibers having a fiber length of more than 10 mm, the wet strength thereof is improved, which is preferable, but the water-decomposability is lowered, and therefore it is not suitable. Further, when the fiber length is less than 1 mm, the wet strength is lowered, which is not preferable. Therefore, it is usually preferable to use a fiber having a fiber length within the above range.

For example, when softwood pulp is used as such a fiber, the softwood is processed into bleached kraft pulp (hereinafter referred to as NBKP) fiber in advance, and the paper produced by beating the softwood without impregnating the binder is used in the present invention. It can be used as a water-decomposable nonwoven fabric, but when it is used in a wet state, its wet strength may be slightly small depending on the application.

Therefore, in such a case, it is preferable to mix and use flat rayon with softwood pulp. Flattened rayon is conventionally called a general self-adhesive rayon. For example, rayon SBH (trade name of Daiwa Boshoku Co., Ltd.)
And so on.

The flat rayon has a flat cross section and a smooth surface, so that the contact area between the fibers is large, and therefore the frictional resistance is large, and the wet strength of the product can be improved. When a non-woven fabric prepared by using such flat rayon in water is discarded, a sufficient amount of water enters between the fibers, and it is easily hydrolyzed, which is preferable.

The composition of such fiber pulp for papermaking and flat rayon, when mixed and used so that the weight ratio becomes 1: 0 to 1: 5, the wet strength and water disintegratability of the resulting water-decomposable nonwoven fabric are improved,
Moreover, it is preferable because it has a good feel and is excellent in cost.

Moreover, this flat rayon is not limited to the above,
Hollow flat rayon or other shapes can be used as long as the frictional resistance between the fibers is large, and the present invention is not limited to these.

The water-decomposable non-woven fabric base material used in the present invention is produced by a wet method or a drying method which is usually used for the above pulp or fiber.

For example, when making a water-decomposable non-woven fabric substrate by the wet method,
For example, Sumireze (registered trademark) 67
5 (manufactured by Sumitomo Chemical Co., Ltd.) and other polyamide epoxy internal additive resins for papermaking can be appropriately added.
If the addition amount is large, the water-decomposability of the obtained water-decomposable non-woven fabric is deteriorated, which is not preferable. For example, when the above-mentioned Sumireze 675 is used for NBKP (beating degree 30 ° SR),
It may be added so as to be contained in P in an amount of 0.2% by weight or less.

The selection of the water-insoluble resin partially provided on the surface layer of the water-decomposable non-woven fabric substrate is determined by its treatment method. As the treatment method, a spraying method, a spraying method, a powder method, a paste dot method or a printing method which has been conventionally used can be preferably used.

For example, when the water-insoluble resin is provided on the water-decomposable non-woven fabric substrate by a spraying method or a powder dot method, a thermoplastic resin powder is used.

Specific examples of the thermoplastic resin powder include polyethylene, polypropylene, polyamide, thermoplastic polyester, and ethylene-vinyl acetate copolymer.

When the water-insoluble resin is provided on the water-decomposable non-woven fabric substrate by a printing method, it is preferable to use a paste obtained by heating and melting the above-mentioned thermoplastic resin or a resin adhesive solution. The resin adhesive liquid is classified into a solvent-soluble type and a water-dispersed type, and any adhesive liquid can be used in the present invention. In order to prevent the resin adhesive solution from penetrating into the inner layer of the water-decomposable non-woven fabric substrate, it is preferable to perform viscosity adjustment such as thickening as necessary.

Examples of the water-dispersible resin adhesive liquid include polyacrylic acid ester-based, polyvinyl acetate-based, urea formalin-based, phenol resin-based and rubber-based liquids such as natural rubber, nitrile rubber, and styrene rubber.

When the water-insoluble resin is provided on the water-decomposable non-woven fabric substrate by the spray method, the suspension of fine powder of the thermoplastic resin or the same solvent-soluble or water-dispersible resin adhesive solution as described above can be used. In this case, when a solvent-soluble resin adhesive liquid is used as the resin adhesive liquid, a solvent or dispersion medium is used as the solvent or the dispersion medium in order to prevent the adhesive liquid from penetrating into the inner layer of the water-decomposable nonwoven fabric substrate. It is necessary to volatilize it in the surface layer of the material, and therefore it is necessary to heat the water-decomposable non-woven fabric substrate in advance, and it is preferable to use a water-dispersible resin adhesive solution from the viewpoint of safety and hygiene of work.

The treatment amount of the water-insoluble resin partially provided on the surface layer of the water-decomposable nonwoven fabric varies depending on the treatment method and the type of the water-insoluble resin, but is usually 0.
It is 5 to 6 g / m ² .

As an example, when a resin powder (100 mesh pass) of ethylene-vinyl acetate copolymer (hereinafter referred to as EVA), which is a thermoplastic resin, is treated by the powder spraying method, the treatment amount is 1 to 4 g / m ² . Is appropriate.

The water-insoluble resin may be provided on at least one surface of the water-decomposable non-woven fabric substrate, and thus may be provided not only on one surface of the water-decomposable non-woven fabric substrate, but also on both surfaces thereof.

When the water-insoluble resin is impregnated inside the water-decomposable non-woven fabric substrate, the texture of the non-woven fabric is impaired, the workability of making a break is reduced, and further the water-decomposability is reduced during use. Therefore, it is preferable to impregnate only the thinnest surface layer of the water-decomposable non-woven fabric substrate. The thickness of the impregnated layer of such a water-insoluble resin, its treatment method,
Since it depends on the type, it is appropriately determined.

The form of the water-insoluble resin provided on the water-decomposable non-woven fabric substrate is, for example, a random dot shape as shown in FIG. 1, an ordered dot shape as shown in FIG. 2, and a form shown in FIG. Examples of such forms include an ordered dash shape and a spider web shape as shown in FIG. 4, but the present invention is not limited thereto and may have any shape.

For example, when the water-insoluble resin (12) is provided in the form of random dots, the treatment method is a spraying method or a spray method, and when the water-insoluble resin (12) is provided in the form of ordered dots, the powder dot method, the paste dot method, the printing method, etc. When provided in a dash shape, a printing method or the like is preferable.

The water-insoluble resin (12) may be provided on the water-decomposable non-woven fabric substrate, and then preliminarily adhered to the water-decomposable non-woven fabric substrate by, for example, an infrared heater, and then thermocompression bonded. After that, it may be directly subjected to thermocompression bonding.

Although the cut is a perforation in the present invention, a discontinuous dotted line cut all the non-woven fabric cross section, a so-called perforated cut or a water-insoluble resin of the surface layer provided with a water-insoluble resin is only cut. It may be a half-cut cut made. Therefore, when both sides of the water-decomposable non-woven fabric are treated with the water-insoluble resin, similar cuts may be provided on both sides. Further, a water-insoluble resin and a cut may be provided on one surface, and a cut and / or a water-insoluble resin may be provided on the other surface. Among these methods, from the viewpoint of workability, the method of making the perforation of the perforation differs depending on the type of water-decomposable non-woven fabric, the generation state of paper powder, and also depends on the length of the fiber of the water-decomposable non-woven fabric to cause water-decomposition. It is decided each time because the ease is different. To reduce the generation of paper dust in the wet state, increase the treatment amount of water-insoluble resin,
The fiber length of the water-decomposable non-woven fabric substrate may be increased, but the water-decomposability on one side thereof is lowered, so it is necessary to increase the number of partial cuts such as perforations to which the non-woven fabric is applied.
However, in order to increase the number of these partial cuts, there is a limit to the mechanical processing method.Therefore, the treatment amount of the water-insoluble resin and the fiber length of the water-decomposable non-woven fabric substrate should be adjusted according to the state of paper dust generation. It is preferable to adjust while watching.

Further, it is preferable that the partial cuts to be made in the partially resin-treated water-insoluble non-woven fabric base material are dispersed as uniformly as possible in view of the water-decomposability of the water-decomposable non-woven fabric base material. For example, when perforations such as perforations are made in a fine lattice pattern, when the obtained water-decomposable non-woven fabric is hydrolyzed, it will be close to a square shape and will be dispersed into small pieces, which will block in the sewer pipe and function as a simple septic tank. It is preferable because it does not interfere with. Therefore, any shape may be used as long as it is a discontinuity that is dispersed into small pieces during water dissolution. In addition, since the water-insoluble resin provided on the uniformly treated water-decomposable non-woven fabric can be easily hydrolyzed, a method of cutting only this layer, for example, a half cut can be preferably used. The shape of the cut may be any of a dotted line, a broken line, an L-shape, a cross, a semicircle, and the like, and the present invention is not limited to these shapes.

Next, the water-decomposable nonwoven fabric of the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1 Hollow flat rayon SBH (thickness: 1.5 denier, fiber length: 5 m
m, Daiwa Boshoku Co., Ltd. 2.34 g (dry weight) and NBKP (beating degree 30 ° SR) 11.47 g (water content 79.6%) were put in a household mixer (SJ-610 manufactured by Sanyo Electric Co., Ltd.). And then 500 ml of water
In addition, the mixture was stirred for about 1 minute, and both were thoroughly mixed and disaggregated. Next, this fiber dispersion was paper-made according to the TAPPI standard hand-making method (standard of the American Paper and Pulp Association), and a 25 cm × 25 cm water-decomposable non-woven fabric substrate (weighing: 80.6 g / m ² , thickness: 0.18 mm, density 0.45 g /
cm ³ ) was prepared.

The resulting water-decomposable non-woven fabric substrate was cut into 20 cm x 20 cm, and EVA resin powder (made by Steel Chemical Co., Ltd., Flowback (registered trademark) Q 16079N 100 mesh pass) 100 mg was cut on one side.
Was evenly dispersed using a JIS test sieve (100 mesh). This was heated on a hot plate provided with an infrared heater of 130 ° C. for 90 seconds in advance, and then thermocompression bonded at 130 to 150 ° C. for 90 seconds via a Teflon sheet having a thickness of 50 μm.

Next, grid-like perforations (width: 0.8 mm, length: 0.1 mm) penetrating to the back side of this water-decomposable non-woven fabric are provided so that the distance between the perforations is 3 mm as shown in FIG. A water-decomposable nonwoven fabric was produced.

As the physical properties of the obtained water-decomposable nonwoven fabric, the wet tensile strength, the breaking length, the elongation, the generation state of paper dust and the water-decomposability were examined by the following methods.

(Wet tensile strength) The obtained water-decomposable nonwoven fabric has a width of 15 m as shown in FIG.
After cutting into strips with a length of 90 mm and a length of 90 mm, gently soak in distilled water for 10 seconds, take out and wipe the water lightly with filter paper, and attach to a universal compression tensile tester (TCM-200, Shinko Communication Industry Co., Ltd.) The test was conducted under the conditions of a pulling speed of 30 mm / min and a test gripping interval of 50 mm, and the load indicated value at the time of breaking the test piece was taken as the tensile strength.

The tensile strength when wet is preferably 100 g or more for practical use.

(Tear length) The tear length was measured based on JIS P 8113.

(Elongation) Elongation was measured based on JIS P 8132.

(Paper dust generation state and water-decomposability) The water-decomposable non-woven fabric obtained above was cut into 10 cm x 20 cm, and folded in half to have a size of 10 cm x 10 cm with the surface coated with the water-insoluble resin as the upper surface. After that, distilled water was sprayed by a sprayer so that the impregnated amount would be 200% of the dry weight of the nonwoven fabric to make a wet tissue, and then the generation state of paper dust and the water decomposability were examined. Regarding the state of paper dust generation, the transparent glass plate was rubbed with wet tissue about 10 times, and the fibers were detached. The generation state of paper dust was judged based on the following judgment criteria.

A: No detachment of fibers was observed on the glass plate.

B: Detachment of 2-3 fibers is observed on the glass plate.

C: Desorption of 5 to 10 fibers is observed on the glass plate.

D: Detachment of 10 to 20 fibers is observed on the glass plate.

E: Many fibers are desorbed on the glass plate.

Further, as shown in FIG. 7, the water disintegration test was carried out by using one graduated cylinder (1) with one test sample (2) and water (3).
After putting 500 ml and covering with a wrap (4), shaking was performed with a horizontal reciprocating shaker at an amplitude of 40 mm and a shaking speed of 240 times / minute for 5 minutes, and the following items were measured.

(A) Time until the original shape of the test sample disappears (b) Maximum size of broken pieces after shaking for 5 minutes (c) Dispersion: Pieces generated after shaking for 5 minutes were included The fiber dispersion was put into a mesh (opening interval: 4.76 mm) sieve, rinsed twice in a watered container, filtered,
The residue was dried, the weight was calculated, and the degree of dispersion was calculated by the following formula.

Wo: Weight of test sample W: Residual weight These results are shown in Table 1.

Comparative Example 1 1.6 g of commercially available toilet paper (weighing 20 g / m ² ) was taken,
Folded into four layers, and in the same manner as in Example 1, the wet tensile strength, the breaking length, the elongation, the generation state of paper dust, and the water decomposability were examined. These results are also shown in Table 1.

From the above results, the water-decomposable nonwoven fabric of the present invention has a much higher wet tensile strength than commercially available toilet paper,
It is recognized that it can withstand practical use. Also, almost no paper dust is generated even when used in a wet state,
Remarkably improved.

Furthermore, in terms of water disintegration, the size of the fragments is slightly larger than that of commercially available toilet paper, but on the contrary, it has excellent dispersibility and is practically 20 mm when considering the functions of sewer pipes and simple septic tanks. There is no problem even if fragments of about 20 mm are generated. Therefore, comprehensively judging the above results, it can be seen that the water-decomposable nonwoven fabric of the present invention has no practical problems and can be sufficiently used.

Examples 2 to 13 Hollow flat rayon SBH having fibers shown in Table 2 (thickness:
1.5 denier, manufactured by Daiwa Spinning Co., Ltd. and NBKP (beating degree 30 ° S)
R) was mixed and disintegrated in the same manner as in Example 1 so as to have the composition shown in Table 2, and then paper-making was performed to obtain a water-decomposable nonwoven fabric base material (weighing: 80 g / m ² ).

The water-decomposable non-woven fabric substrate obtained below was cut into 20 cm × 20 cm, and EVA resin powder was second-coated on one side in the same manner as in Example 1.
Spraying was carried out in the amount shown in the table, and heating and pressure bonding were carried out in the same manner as in Example 1. Next, perforations were provided in the same manner as in Example 1 so that the intervals were 3 mm or 5 mm, and a water-decomposable nonwoven fabric was produced.

As the physical properties of the obtained water-decomposable nonwoven fabric, the wet tensile strength, the breaking length, the elongation, the generation state of paper dust and the water-decomposability were examined in the same manner as in Example 1. The results are shown in Table 2.

From the above results, it is recognized that by partially treating the surface layer of the water-decomposable nonwoven fabric substrate with the water-insoluble resin, the detachment of the fibers from the treated surface in the wet state is remarkably improved. However, if the amount of the water-insoluble resin treated is too large, a problem arises in terms of water decomposability, especially in terms of the size of the fragments after hydrolyzing. When the size of the fragment is large, for example, when the strength of the fragment is small, when it is discarded in the flush toilet, one fragment becomes the core and the fragments are entangled one after another, and finally the sewer pipe It may cause problems such as blockage and obstruction of the function of the simple septic tank. Considering this point, the size of the fragment after hydrolyzing is per side
It is preferable to use it after adjusting it so that it is 30 mm or less.

Thus the process of EVA in the present embodiment is preferably a 1 to 4 g / m ^2, when the processing amount exceeds 4g / m ^2, there is a possibility that problems such as described above occurs, also the amount of processing 1 g / m
^{When it is} less than ² , the amount of paper dust is increased.

However, the treatment of the water-insoluble resin differs depending on the type and treatment method of the resin, and therefore cannot be determined unconditionally. For example, when the powder dispersion method of the thermoplastic resin as in this example is used, the particle diameter is large. This is a factor and is affected by the dot area of one point when performing the printing method, so it must be experimentally determined in each case from the standpoint of paper dust generation and water degradability.

Comparative Example 2 and Comparative Example 3 Hollow flat rayon SBH (thickness: 1.5 denier, manufactured by Daiwa Spinning Co., Ltd.) and NBKP (beating degree of 30) having fiber lengths shown in Table 3
Example 1 so that the composition ratios shown in Table 3 are adjusted so that (° SR)
After mixing and disintegrating in the same manner as in ( ¹ ), paper making was carried out to obtain a water-decomposable non-woven fabric substrate (basis weight: 80 g / m ² ).

The water-decomposable non-woven fabric substrate obtained below was cut into a piece of 20 cm × 20 cm, and EVA resin powder was applied on one side in the same manner as in Example 1
Spraying was carried out in the amount shown in the table, and heating and pressure bonding were carried out in the same manner as in Example 1. Next, perforations were provided in the same manner as in Example 1 so that the intervals were 3 mm or 5 mm, and a water-decomposable nonwoven fabric was produced.

As the physical properties of the obtained water-decomposable nonwoven fabric, the wet tensile strength, the breaking length, the elongation, the generation state of paper dust and the water-decomposability were examined in the same manner as in Example 1. These results are also shown in Table 3.

From the results of Example 1, Example 6 and Comparative Example 3, it is recognized that when the nonwoven fabric is partially cut after the resin treatment, the water decomposability is improved. Further, it is recognized that even if a large number of perforation-like cuts are made, the strength is not extremely reduced and the strength is sufficient for use.

In addition, Example 1, Example 7, Example 8, Example 9, and Example
Hollow flat rayon to NBKP (beating degree 30 ° SR) from 10 results
It is recognized that the wet tensile strength and elongation of the product are remarkably improved by mixing SBH.

Therefore, NBKP (beating degree 30 ° SR) and hollow flat rayon SB
It is preferable to use a non-woven fabric having a composition with H in a weight ratio of 1: 0 to 1: 5 as a water-decomposable non-woven fabric substrate.

Regarding the beating degree of NBKP, if the beating degree of NBKP is high, the fibers are often entangled with each other, so that the generation of paper dust is reduced, but conversely the dispersibility is reduced. If the degree of beating is small, the opposite phenomenon occurs, so the degree of beating of the pulp used for papermaking is determined in consideration of the production condition of paper dust, water disintegration and manufacturing conditions such as pressure in the dehydration step when making paper. Should be.

When NBKP (beating degree 30 ° SR) and hollow flat rayon SBH are mixed and mixed, the water-degradability decreases when the fiber length of rayon is long. For example, from the results of Example 1 and Examples 11 to 13
Water-decomposable 1: 1 mixed paper of NBKP (beating degree 30 ° SR) and hollow flat rayon. When rayon with a fiber length of 10 mm is used as the non-woven fabric substrate, the size of debris after water-decomposition increases and water-decomposability decreases. Is allowed to do. Therefore, in this embodiment, the fiber length of rayon used is suitably 3 to 7 mm. If the fiber length is less than 3 mm, there is little expectation for improving the wet strength of the product. However, when the fiber length of this rayon is mixed with NBKP, it can be used up to a certain length to reduce the amount of rayon used.

Examples 14 to 16 Hollow flat rayon SBH (thickness: 1.5 denier, manufactured by Daiwa Spinning Co., Ltd.) having a fiber length shown in Table 4 and NBKP (beating degree of 30)
Example 1 so that the composition ratio shown in Table 4 may be adjusted to (° SR).
After mixing and disintegrating in the same manner as in ( ¹ ), paper making was carried out to obtain a water-decomposable non-woven fabric substrate (basis weight: 80 g / m ² ).

The resulting water-decomposable non-woven fabric substrate was cut into 20 cm × 20 cm pieces, and a thermoplastic polyamide resin powder (part number: 842P80, manufactured by Toray Industries, Inc., 250 mesh pass) was cut on one side in the same manner as in Example 1 to No. 4. The amount of spray shown in the table was used to spray using a JIS test sieve (200 mesh pass), and heated and pressed in the same manner as in Example 1. Next, perforations were provided in the same manner as in Example 1 so that the distance between them was 3 mm, to prepare a water-decomposable nonwoven fabric.

As the physical properties of the obtained water-decomposable nonwoven fabric, the wet tensile strength, the elongation, the generation state of paper dust and the water-decomposability were examined in the same manner as in Example 1. These results are also shown in Table 4.

When using a resin having a very small particle size from the results of Examples 14 to 16, i.e., when bonding the surface layer of the water-decomposable non-woven fabric substrate to a very small part thereof, from the surface of the non-woven fabric in a wet state. It is recognized that there is a remarkable effect on the detachment of the fibers. Moreover, if the fiber length of the rayon to be used is about 3 mm, it has excellent wet tensile strength and water decomposability, and even if the fiber length is 5 mm, there is no problem if the mixing ratio with NBKP is reduced. There is no.

As described above, the surface layer of the water-decomposable non-woven fabric substrate from Examples 1 to 16 is partially treated with a water-insoluble resin, and a partial cut is made to the non-woven fabric, so that the desorption of the fibers in the wet state can be achieved. It can be seen that a water-decomposable non-woven fabric which can be easily and easily hydrolyzed is obtained.

Examples 17 to 30 The fibers shown in Table 5 were mixed and disintegrated in the same manner as in Example 1 and then paper-made to obtain water-decomposable nonwoven fabric base materials.

The resulting water-decomposable non-woven fabric substrate was cut into 20 cm × 20 cm, and EVA resin powder was applied to one side in the same manner as in Example 1 (made by Iron and Chemicals Co., Ltd., Flowback (registered trademark) Q16079N, 100 mesh pass). Was sprayed in the same manner as in Example 1 so that the sprayed amount was as shown in Table 5, heated and pressed. Next, the cross-shaped perforations were arranged so that the distance between them was 3 mm, and Example 1
A water-decomposable non-woven fabric was prepared in the same manner as above.

Example 31 The non-woven fabric obtained in Example 14 is cut into 10 cm × 20 cm, 10 cm so that the surface provided with a water-insoluble resin is the outside.
It was folded in half into a size of 10 cm and impregnated with an aqueous solution having the composition shown in Table 7 to prepare a wet tissue.

The flowability test of this wet tissue was carried out by using the flush toilet equipment shown in FIG. 8 under the following measuring method and measuring conditions.

(Measurement method) Toilet bowl (JIS A 5207: C316) (7) and 500 mm of the toilet bowl (7)
The low tank (5) provided above and the cock (11) at the upper end
Are connected with a polyvinyl chloride pipe (6) with an inner diameter of 32 mm, and below the toilet bowl (7) is a transparent polyvinyl chloride pipe (8) with an inner diameter of 75 mm and a transparent chloride with an inner diameter of 100 mm with a gradient of 1/100. It is connected to the septic tank (10) with a vinyl pipe (9).

Next, sample (5 pieces of wet tissue) in the toilet bowl (7).
Then, the cock (11) is opened and tap water 10 is flown into the low tank (5) to observe the flowability of the sample in the pipes (8) and (9).

(Measurement conditions) Flow rate: 10 / time Number of tests: 5 / time Number of tests: 50 times The results are shown in Table 6.

For reference, commercially available toilet paper (basis weight: 20 g / m
² ) was used and tested in the same manner as in Example 31. The results are also shown in Table 6.

[Effects of the Invention] The water-decomposable nonwoven fabric of the present invention has sufficient strength even in a wet state at the time of use, but since it hydrolyzes when immersed in a large amount of water, it causes blockage in the sewer pipe or a simple septic tank. It never interferes with the function of.

Further, since the water-decomposable nonwoven fabric of the present invention is made of a material that is safe for the human body and does not generate paper dust when wet, it can be used in wet tissues, dry tissues, hand wipes, cleaning cloths, hospitals, etc. Pants, diapers, etc. are added; by adding a sterilizing agent and a disinfecting agent, it can be applied to various products such as surgery, food gloves, and hats.

[Brief description of drawings]

1, 2, 3, and 4 are plan views showing the shape of the water-insoluble resin provided on the water-decomposable nonwoven fabric of the present invention, and FIG. 5 is provided on the water-decomposable nonwoven fabric of the present invention. FIG. 6 is a plan view showing the shape of the cut, FIG. 6 is a plan view showing the shape of the test piece used in the example of the present invention, and FIG. 7 is a method of shaking the test piece used in the example 2 of the present invention. FIG. 8 and FIG. 8 are views showing the flush toilet equipment of the wet tissue flowability test used in Example 31. (Symbols in Drawings) (1): Measuring Cylinder (2): Test Sample (3): Water (4): Lap (5): Low Tank (6), (8), (9): Polyvinyl Chloride Pipe ( 7): Toilet bowl (10): Septic tank (11): Cock (12): Water-insoluble resin

Claims (3)

[Claims] 1. A water-decomposable non-woven fabric substrate having at least one surface layer partially provided with a water-insoluble resin, and at least a water-insoluble non-woven resin substrate provided with the water-insoluble resin. A water-decomposable non-woven fabric having a cut in the surface layer. 2. The water-decomposable non-woven fabric according to claim 1, wherein the water-decomposable non-woven fabric substrate is a fiber pulp for papermaking or a mixture of fiber pulp for papermaking and flat rayon. 3. The water-decomposable nonwoven fabric according to claim 1, wherein the water-insoluble resin is a heat-meltable resin.