JP3284960B2 - Water-disintegratable nonwoven fabric and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-disintegratable nonwoven fabric which has a strength which can withstand operations such as cleaning in a dry state and a wet state, and which can disintegrate fibers constituting the nonwoven fabric in a large amount of water flow. And its manufacturing method.

More specifically, a water-disintegratable nonwoven fabric in which regenerated cellulose fibers and wood pulp are entangled and integrated,
Maintains practical strength when dried, wetted with water or chemicals for use as a wet tissue, cloth, cleaning wiper, or used as a top sheet for disposable diapers or sanitary napkins. The present invention relates to a water-disintegratable nonwoven fabric which can be easily disaggregated by a large amount of water flow in a toilet or the like, and a method for producing the same.

[0003]

2. Description of the Related Art In general, wet products such as wet tissues, wipes, and wipers for cleaning, and many hygiene products such as disposable diapers and sanitary napkins are discarded as garbage after use. For example, considering the use of wipes, it is better to treat with a wet wiper than when treating with toilet paper, and has excellent performance such as hygiene and low skin irritation. . However, it has a drawback that it cannot be flushed to a flush toilet after use, and disposal treatment tends to be unsanitary.

[0004] For this reason, generally used wipes are used only for very limited uses such as baby wipes and nursing wipes for nursing care, and are not widely used in place of toilet paper. Not reached. As a method for improving the wiping properties of the toilet paper and skin irritation, a method of impregnating the toilet paper with a humectant or the like has been proposed, but it did not reach a performance comparable to the case of using a wet wiper. .

[0005] Examples of the water-disintegrable non-woven fabric usable as a top sheet for wet tissues and sanitary articles include, for example, JP-A-47-9486, JP-A-1-168999, JP-A-2-149237, and JP-A-3-149. 27
No. 7,335, JP-A-4-370300, and Japanese Patent Application No. 8-142825 have been proposed.

In Japanese Patent Application Laid-Open No. 47-9486, a binder solution containing polyvinyl alcohol and borax is sprayed on a sheet and then heated and dried, whereby the polyvinyl alcohol and borax react to temporarily provide water resistance. It is described that the obtained hydrolyzed paper is useful as an absorbent pad for napkins, diapers and the like. However, this water-disintegrated paper does not have the strength to withstand the wiping of the buttocks or the cleaning work that requires mechanical force such as that used for a cleaning sheet for a toilet or the like when impregnated with water.

JP-A-1-168999 proposes to use a calcium salt of water-insoluble carboxymethylated pulp for a base paper. However, in the water-disintegrated paper proposed in the publication, the upper limit of the water content in the cleaning liquid is 60%, and it is necessary to add at least 30% of an organic solvent such as alcohol. The applications where the liquid can be used are limited, and it is particularly difficult to use for applications such as ass wiping.

Further, by adding an organic solvent, it is necessary to add a large amount of fragrance for eliminating the smell of the organic solvent, and the strength is reduced during cleaning work due to an increase in the water content due to volatilization of the organic solvent. There is a disadvantage that there is. Furthermore, the adverse effect on the human body due to the high concentration of the organic solvent cannot be ignored.

Japanese Patent Application Laid-Open No. 2-149237 discloses that a water-disintegrated paper containing a specific water-soluble binder contains an aqueous solution containing a specific metal ion and an organic solvent.
We propose to obtain a water-disintegratable cleaning article that has sufficient strength to perform cleaning work in a state of being impregnated with a water-containing cleaning agent, and has a water-disintegrating performance that can be easily washed away in a toilet or the like. I have.

However, in this cleaning article, it is necessary to include a specific metal ion and an organic solvent in the impregnating liquid to be impregnated into the hydrolyzed paper, and the impregnating liquid cannot be freely selected according to the purpose. Becomes very limited. Further, a water-soluble binder having a carboxyl group is used as a specific water-soluble binder, and as such a water-soluble binder, carboxymethyl cellulose, carboxyethyl cellulose, polysaccharide derivatives such as alkali metal salts such as carboxymethylated starch, synthetic polymers, natural polymers However, the blending of these binders has the disadvantage that the texture of the sheet becomes hard.

In JP-A-3-277335, water-soluble carboxymethylcellulose calcium is used as a paper-strength enhancer for a base paper, and calcium ions coexist in the cleaning solution, so that even a cleaning solution having a high water content is sufficient. A wiping material that exhibits strength and easily disperses in water at 100% water has been proposed. As a calcium ion source, calcium chloride or calcium acetate is used. However, it is difficult to clean the skin such as wiping a butt, which is likely to cause rough hands when used as a wiping material. The upper limit of the water content during the impregnation is also about 85%. However, from the viewpoint of diversification of uses, a base material that can be used even if the water content in the impregnating liquid is even higher is desired.

Japanese Patent Application Laid-Open No. Hei 4-370300 has a multilayer structure having at least two layers, and one outermost layer has 10 layers.
~ 60% paper strength agent, the other outermost layer is 5% by weight
Hydrolysis papers containing the following paper-strengthening agents have been proposed. As the paper strength enhancer used for the outermost layer of the hydrolyzed paper, a salt of carboxymethylated pulp, water-soluble polyvinyl alcohol, water-soluble polyvinyl alcohol fiber, or a mixture thereof is used.

This water-disintegrated paper is intended to improve the productivity by reducing the deterioration of the releasability in the dryer part during papermaking due to the addition of a paper strength enhancer. However, when there is much water in the chemical solution to be impregnated, it is difficult to provide sufficient wet strength for use, and the texture is hard because a large amount of paper strength enhancer is compounded in the outermost layer on one side of the hydrolyzed paper Will be.

In view of these drawbacks of hydrolyzed paper, the present inventors have proposed a water-disintegrable nonwoven fabric which has no binder and has sufficient strength and water disintegration for use, and a method for producing the same. That is, Japanese Patent Application No. 8-142825 discloses that a web made by mixing 40 to 85% by weight of a regenerated cellulose fiber having a specific fiber length and 15 to 60% by weight of a pulp fiber having a specific freeness is subjected to a high-pressure jet flow on a wet paper-made web. Is applied to give a fiber entanglement to obtain a water-disintegratable nonwoven fabric having both wet strength and water-disintegrability. However, the water-disintegratable nonwoven fabric has a high content of rayon fibers as large as 40 to 80% by weight, so that the cost becomes high.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fiber which has a strength which can withstand operations such as cleaning in a dry state and a wet state, and which constitutes a water-disintegratable nonwoven fabric in a large amount of water flow. The present invention provides a water-disintegratable nonwoven fabric which can be disintegrated and a method for producing the same.

[0016]

In view of this situation, the present inventors have developed a water-disintegratable nonwoven fabric which has strength enough to be used in a wet state and easily disintegrates into a fibrous form in a large amount of water. We studied diligently about the manufacturing method.

As a result, in a water-disintegratable nonwoven fabric in which a regenerated cellulose fiber and a wood pulp are formed into a web by a wet papermaking method and then subjected to a high-pressure water column treatment to entangle and integrate the web, a specific regenerated nonwoven fabric is used. Wet papermaking using cellulose fiber and specific wood pulp as raw materials and then subjecting it to high-pressure water column flow treatment ensure strength that can withstand use even when wood pulp is blended at a high rate and water disintegration in large amounts of water flow. They have found that they can achieve both, and have completed the present invention.

The first aspect of the present invention is a nonwoven fabric in which regenerated cellulose fibers and wood pulp are entangled and integrated, and the nonwoven fabric is 15 to 55% by weight of regenerated cellulose fibers having a fineness of 1.0 to 5.0 denier. And Runkel ratio 0.35 to 0.55
With a freeness of 550-750 ml CSF wood pulp 85
5cm x 5cm (25c
When the non-woven fabric having a size of m ² ) is put into 100 ml of pure water and shaken at a shaking speed of 300 cycles / minute and disintegrated in water, the disintegration until the maximum piece size becomes 1 cm ^2. Water disintegration expressed by the time required for 60 to 300 seconds,
The geometric average value of the wet tensile strength of the nonwoven fabric measured according to JIS P8135 expressed by the formula (1) is 200 to
It is a water-disintegrable nonwoven fabric of 1000 gf / 25 mm. Geometric mean of wet tensile strength = (XY) ^1/2 (1) where, X: wet tensile strength of water-disintegratable nonwoven fabric in longitudinal direction (g)
f / 25 mm), Y: transverse tensile strength of water-disintegratable nonwoven fabric (gf / 25)
mm).

[0019]

[0020]

The second aspect of the present invention is a non-woven fabric in which regenerated cellulose fibers and wood pulp are entangled and integrated, and the non-woven fabric has a denier of 1.0 to 5.0 denier and a regenerated cellulose fiber of 15 to 55% by weight. And 85-45% by weight of wood pulp having an α-cellulose content of 85-88% by weight,
× 5 cm (25 cm ² ) of the nonwoven fabric of 100 m
1 cm of pure water and shaken at a shaking speed of 300 cycles / min and disintegrated in water, the largest piece size is 1 cm
Water disintegration expressed by the time required for disaggregation to reach ² is 6
It is a water-disintegratable nonwoven fabric having a wet tensile strength of 200 to 1000 gf / 25 mm, represented by the formula (1), of the wet tensile strength of the nonwoven fabric measured from 0 to 300 seconds according to JIS P 8135.

[0022] invention relating to claim 2 of the present invention, a web was formed by a known wet papermaking method using any one of materials constituting the water-decomposable non-woven fabric, then perforated support the web A high-pressure water jet stream is jetted onto the web surface under the condition that the added specific energy E represented by the formula (2) is 0.07 to 0.20 kWh / kg, and the regenerated cellulose fiber is formed by a hydroentanglement method. A method for producing a water-disintegratable nonwoven fabric, wherein the nonwoven fabric is obtained by entanglement and integration with wood pulp. E = (A × (2 / ρ) ^1/2 × (g × P) ^3/2 ) / (M × 60 × S) (2) where A is the sum of the nozzle hole areas (m ² / m) E: Additional specific energy (kWh / kg) ρ: Water density (kg / cm ³ ) g: Gravitational acceleration (m / s ² ) P: Water pressure at nozzle part (Pa) S: Web passing speed (m / Min) M: Web mass (g / m ² ).

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION In order to obtain the water-disintegrable nonwoven fabric of the present invention, first, a wet papermaking web comprising regenerated cellulose fibers and wood pulp is prepared. The regenerated cellulose fibers used here are made of a solution of cellulose such as wood pulp or cotton linter in the form of viscose, and then regenerated and spun cellulose in an acid. After dissolving, regenerate in acid
Regenerated cellulose fibers obtained by dissolving cellulose in a non-aqueous cellulose solvent such as spun copper ammonia rayon or N-methylmorpholine-N-oxide and then spinning the same can be used.

The fineness of the regenerated cellulose fiber used in the present invention is from 1.0 denier (hereinafter referred to as d) to 5.0 d.
Range. When the fineness of the regenerated cellulose fiber is less than 1.0 d, it is difficult to disperse during wet paper making, and it is difficult to obtain a wet paper web with good formation. Also, regenerated cellulose fibers having a fineness of less than 1.0 d are difficult to stably produce and are difficult to obtain at low cost. Further, the rigidity of the fiber itself tends to be low, and the fiber entanglement due to the high-pressure water column flow treatment is too strong, and the water disintegration tends to be poor.

Conversely, the fineness of the regenerated cellulose fiber is 5.0 d.
If it exceeds 300, the texture of the resulting water-disintegratable nonwoven fabric tends to be hard, resulting in a poor touch feeling. The L / D of the regenerated cellulose fiber used is in the range of 250 to 900. When the L / D of the regenerated cellulose fiber is less than 250, the flexibility of the fiber is insufficient, and even if the wet papermaking web obtained is subjected to a high-pressure water column flow treatment, sufficient fiber entanglement cannot be obtained. The strength is inferior.
Conversely, when the L / D of the regenerated cellulose fiber exceeds 900,
During wet papermaking, the fibers are difficult to disperse uniformly, and it is difficult to obtain a well-formed wet papermaking web. In addition, the entanglement of the fibers due to the high-pressure water column flow treatment becomes too high, and the water-disintegrable property of the obtained water-disintegratable nonwoven fabric becomes poor.

On the other hand, wood pulp used by mixing with the regenerated cellulose fiber has a Runkel ratio of 0.35 to 0.5.
Canadian standard freeness is 550-750ml in the range of 55
It must be a CSF wood chemical pulp. For example, for wood pulp, unbleached chemical pulp obtained by digesting softwood or hardwood by the Kraft method, soda method, polysulfite method, or the like, or bleached chemical pulp bleached to a Hunter brightness of 70 to 90% is used alone. Or mixed and used.

Usually, the Runkel ratio of wood pulp is measured in the state of wood chips (chips). In the present invention, the Runkel ratio of pulp in a state where wood is digested and bleached is important. The Runkel ratio is
The ratio of the fiber wall thickness to the lumen diameter in the wet state of the pulp immediately before use is defined.The higher this value is, the higher the Runkel ratio is, the greater the fiber wall thickness is, the more rigid the fiber is, and the higher the bonding strength is. Although it is difficult to express, in the present invention, it is measured and calculated as follows.

1. The wood pulp is immersed in water for 3 days, dehydrated, and aligned in a wet state so that the fiber directions are the same, and hardened with an adhesive. 2. This sample is cut with a knife and a cross-sectional photograph is taken. 3. 3. Obtain the outer circumference of the fiber wall and the cross-sectional area of the fiber wall from the cross-sectional photograph by an image analysis method. Calculate the fiber diameter and lumen diameter by the following formula. 2R = X / π 2r = 2 [(πR ² −S) / π] ^1/2 R: fiber radius r: lumen radius X: outer circumference of fiber wall S: fiber wall cross-sectional area The Runkel ratio is calculated by the following equation. Runkel ratio = (R−r) / r

The Runkel ratio of wood pulp is determined by wood species, tree species,
Depending on the growth environment, etc., in coniferous wood, the Runkel ratio of pulp from Western Hemlock, Douglas fir, spruce, etc. is large, the Runkel ratio of pulp from red cedar, radiata pine, etc. is small, and even the same tree species Summer wood tends to have a larger Runkel ratio than spring wood.

The Runkel ratio of pulp from a single tree species from naturally occurring wood is in the range of 0.1 to 2.0, but commercially available wood pulp usually has various Runkel ratios. Pulp is mixed. In the present invention, the average value of the Runkel ratio of the pulp used is 0.35 to
If it is in the range of 0.55, it can be suitably used.
In the present invention, when a wood pulp having a Runkel ratio of less than 0.35 is used, the entanglement of the wood pulp due to the high-pressure water column treatment becomes too strong, and the water-disintegrable nonwoven fabric obtained has poor water-disintegration properties. Since the pulp having a high Runkel ratio has rigidity, there is a concern that the flexibility of the nonwoven fabric using this pulp may be impaired, and the pulp used in the present invention must be available in large quantities on a commercial scale. The upper limit of the Runkel ratio is 0.55. A particularly preferred Runkel ratio is 0.40 to 0.55.

It is necessary to use a wood pulp fiber having a Canadian standard freeness shown in JIS P 8121 of 550 ml or more. When the freeness is less than 550 ml, the bonding force between the wood pulp fibers becomes too strong, and the water disintegrability of the resulting water-disintegratable nonwoven fabric becomes poor, and a large amount of the washed-out material during high-pressure water column flow treatment is generated. It is not economical. The freeness is highest when wood pulp is used without being beaten. Generally, the freeness of unbeaten wood pulp is about 750 ml to 650 ml.

In the present invention, the fineness is 1.0 to 5.0 d, L /
55 to 15% by weight of regenerated cellulose fiber having a D of 250 to 800, and wood pulp 4 having a Runkel ratio of 0.35 to 0.55.
5 to 85% by weight to form a wet papermaking web using a conventionally known papermaking machine such as a round papermaking machine, a short netting machine, an inclined wire papermaking machine, a fourdrinier papermaking machine, and then a high pressure water column. Perform flow treatment.

The mixing ratio of the regenerated cellulose fiber and the wood pulp is 55 to 15% by weight / 45 to 85% by weight. When the blending ratio of the regenerated cellulose fiber is less than 15% by weight,
Fiber entanglement due to high-pressure water column flow treatment is insufficient, and a sheet having sufficient strength cannot be obtained. Conversely, if the blending ratio of the regenerated cellulose fiber exceeds 55% by weight, the ratio of the regenerated cellulose fiber, which is more expensive than wood pulp, increases, and it becomes difficult to produce the resulting hydrolyzable nonwoven fabric at low cost.

JIS P 8124 for wet papermaking web
Is 30 g / m ^{2 to} 80 g /
It is preferably in the range of m ² . When the grammage is less than 30 g / m ² , the strength tends to be insufficient when the obtained water-disintegratable nonwoven fabric is used for an application such as a wiper, and the water-disintegratable nonwoven fabric is more likely to break during use and become unusable. Conversely, the grammage is 80
If it exceeds g / m ² , the sheet will have an increased stiffness and will be difficult to use, and the water-disintegratable nonwoven fabric will tend to have poor water-disintegration properties when poured into a water stream.

The high pressure water column flow treatment can be carried out by a conventionally known method. That is, the web is placed on a porous support such as a wire mesh, and a water pressure of 15 to 150 kg / cm ² is passed from the upper surface of the web through a nozzle having a large number of pores having a diameter of about 0.08 mm to 0.30 mm. High-pressure water is jetted with water pressure, and the fibers constituting the web are entangled with each other. The energy applied to the web by the high-pressure water column flow treatment is represented by the additional specific energy of the formula (2), and in the present invention, is 0.07 to 0.200 kWh /
It is preferable to perform the high-pressure water column flow treatment under such conditions that the pressure becomes equal to kg. E = (A × (2 / ρ) ^1/2 × (g × P) ^3/2 ) / (M × 60 × S) (2) where E: additional specific energy (kWh / kg) ρ: water Density (kg / cm ³ ) g: gravity acceleration (m / s ² ) P: water pressure at the nozzle (Pa) S: web passing speed (m / min) M: web mass (g / m ² )

The additional specific energy is 0.07 kWh / kg
If less than, the fiber entanglement imparted by the high-pressure water column flow treatment is insufficient, the strength of the obtained water-disintegratable nonwoven fabric is weak, and the fibers constituting the water-disintegratable nonwoven fabric are difficult to arrange in the thickness direction of the sheet, The texture may be paper-like. Conversely, the added energy is 0.2
If it exceeds 00 kWh / kg, entanglement between fibers becomes too strong, and the water-disintegrable property of the obtained water-disintegratable nonwoven fabric may be poor.

The high-pressure water column flow treatment may be carried out online immediately after wet-papermaking to form a web, or the wet-paper-made web may be dried once and then subjected to online or offline high-pressure water column flow treatment. .

[0038] To obtain the water-decomposable non-woven fabric according to the present invention, in addition to using wood pulp having a specific Runkeru ratio as mentioned heretofore as a raw material, identified as regenerated cellulose fibers
From mixtures with wood pulp with a range of alpha cellulose content
Used as charges, it may be subjected to high-pressure water jet treatment in the same manner as obtaining the water-decomposable non-woven fabric.

As a method for obtaining substantially the same effect as the present invention,
Carboxyme is one of the fibers constituting the water-disintegratable nonwoven fabric.
Chilled fibers can also be used. Carboxymethylation
The fibers are carboxymethylated from cellulosic fibers such as wood pulp and regenerated cellulose fibers, and have a substitution degree of 0.3 to
It is a fibrous material having 0.5, preferably 0.35 to 0.45 carboxymethyl groups.

If the degree of substitution is less than 0.3, the carboxymethyl group is so small that sufficient water-decomposability cannot be imparted. On the other hand, if the degree of substitution is larger than 0.5, the fibers are dissolved or swelled in water, so that a raw material containing the fibers cannot be wet-formed, which is not suitable.

The carboxymethyl group of the carboxymethylated fiber often forms a sodium salt due to its production method, but significantly promotes the solubility or swelling of the fiber in water in correlation with the degree of substitution. I do. Carboxymethyl
The carboxymethyl groups of the modified fibers must have 10 to 60% of the total carboxymethyl groups converted to carboxylic acids. When the proportion of the carboxylic acid is less than 10%, the carboxymethylated fibers dissolve in water during wet papermaking, and a web cannot be obtained. When the proportion of the carboxylic acid exceeds 60%, the carboxymethyl group of the sodium salt type becomes insufficient,
It is not suitable because water disintegration cannot be imparted to the nonwoven fabric.

The average fiber length of the carboxymethylated fiber is
It is preferably from 0.5 to 5.0 mm. When the fiber length is less than 0.5 mm, the fiber yield during wet papermaking deteriorates. Conversely, when the fiber length exceeds 5.0 mm, fiber entanglement occurs strongly when the hydroentanglement method is applied, and nonwoven fabric May degrade the water disintegration of

The content of carboxymethylated fiber was 3 per weight of the absolute dry mixture of regenerated cellulose fiber and wood pulp.
-17, preferably 4-12% by weight. Content 3
When the amount is less than% by weight, the performance hardly changes even when the hydroentanglement method is applied, as compared with the case where no carboxymethylated fiber is blended. When the content of the carboxymethylated fiber is 3% by weight or more, the effect of improving the water decomposability of the nonwoven fabric is recognized, and the effect becomes more remarkable by increasing the distribution. However, when the content is higher than 17% by weight, the water disintegrability is greatly improved, but the texture of the water decomposable nonwoven fabric is remarkably reduced, and the product cost is extremely high. The blend of carboxymethylated fiber has a Runkel ratio of 0.35
It is also effective when using wood pulp in the range of 0.55.

When a carboxymethylated fiber is blended with the regenerated cellulose fiber and wood pulp to obtain a water-disintegratable nonwoven fabric, the regenerated cellulose fiber and wood pulp that can be used are as follows. In other words, the regenerated cellulose fibers were prepared by dissolving the cellulose in a viscose rayon and cellulose in a copper ammonia solution after regenerating and spinning the cellulose in an acid, after the cellulose such as wood chemical pulp and cotton linter was dissolved in the form of viscose. After that, regenerated and spun copper acid rayon in an acid, regenerated cellulose fibers obtained by dissolving cellulose in a non-aqueous cellulose solvent such as N-methylmorpholine-N-oxide, and then spinning. it can.

The length of the regenerated cellulose fiber is 3 to 15 m
It is preferably in the range of m. If the length is less than 3mm,
When the hydroentanglement method is applied, the entanglement of the regenerated cellulose fiber becomes too weak, and a sufficient wet strength cannot be obtained.
Conversely, if the length is greater than 15 mm, poor dispersion will occur during wet papermaking, the formation of the sheet will be poor, the entanglement will be too strong by the hydroentanglement method, and the nonwoven fabric will come in contact with a large amount of water. It is difficult to destroy the configuration.

The fineness of the regenerated cellulose fiber is 1.0
It is in the range of 5.0 denier. If the fineness is less than 1.0 denier, dispersion becomes difficult during wet papermaking, and a wet web with good texture cannot be obtained. In addition, regenerated cellulose fibers having a fineness of less than 1.0 denier are difficult to manufacture stably, so they are difficult to obtain at low cost, and the rigidity of the fibers themselves tends to be low. This is not suitable because the nonwoven fabric has poor water dissolvability as a result. Conversely, the fineness of the regenerated cellulose fiber is 5.
When it exceeds 0 denier, the obtained water-disintegratable nonwoven fabric becomes hard, and the texture and the feel are inferior.

The diameter of the regenerated cellulose fiber used is D,
When the length is L, the ratio of the diameter to the length, L / D, is
It is preferably in the range of 250 to 900. When the L / D of the fiber is less than 250, the flexibility and flexibility of the fiber are insufficient, and even if the web containing such regenerated cellulose fiber is subjected to the hydroentanglement method, sufficient fiber entanglement of the regenerated cellulose fiber is obtained. The wet strength of the obtained water-disintegratable nonwoven fabric is deteriorated. Conversely, if the L / D of the regenerated cellulose fiber exceeds 900, it becomes difficult to uniformly disperse the fiber during wet papermaking, and not only is a good-formed web obtained, but also strong fiber entanglement is caused by the hydroentanglement method. As a result, the water disintegration of the nonwoven fabric tends to be extremely poor.

The fiber may be in the form of staples or pulp fibers. The cross-sectional shape of the fiber is not limited to a circle, but may be an irregular cross-sectional shape such as a hollow circular shape or a star shape, or a divided shape.

The wood pulp is made of unbleached chemical pulp obtained by digesting softwood or hardwood by the kraft method, soda method, polysulfite method, or the like. Bleached chemical pulp or the like can be used alone or in combination.

The Canadian standard freeness according to JIS P 8121 of the wood pulp is preferably in the range of 550 to 750 ml CSF. The freeness of bleached pulp before beating differs depending on the degree of cooking, bleaching conditions, etc.
Range from 50 to 750 ml CSF and 650 ml CS
If pulp with a freeness of less than F is used, it must be beaten with a refiner. However, the freeness is 550
If pulp less than ml CSF is used, the cohesion between the pulp fibers will be high when mixed with regenerated cellulose fibers to form a web in the wet process, resulting in a high density and stiff web and hydroentanglement of the web. Even after applying the law,
Although the wet strength of the resulting water-disintegratable nonwoven fabric is significantly higher,
Conversely, the water disintegration of the non-woven fabric is significantly deteriorated, which is not suitable.

The mixing ratio of the regenerated cellulose fiber and the wood pulp is in the range of 15 to 55% by weight of the regenerated cellulose fiber and 85 to 45% by weight of the wood pulp. When the proportion of the regenerated cellulose fiber is less than 15% by weight, the product cost is low, but even when the fiber is entangled by high pressure water jet treatment, a nonwoven fabric having sufficient wet strength and excellent water disintegration can be obtained. Absent. Conversely, when the blend of regenerated cellulose fiber is 5
If it exceeds 5% by weight, sufficient entanglement of the fibers cannot be obtained unless the wood pulp is beaten to make the bond strength easy to express and large energy is applied during high-pressure water jet flow treatment. In addition, the cost of regenerated cellulose fibers, which are more expensive than wood pulp, is higher, which increases the product cost of the nonwoven.

The basis weight of the web measured by a method according to JIS P 8124 is preferably in the range of 30 to 80 g / m ² . When the grammage is less than 30 g / m ² , the strength tends to be insufficient when the obtained water-disintegrable nonwoven fabric is used for a wiper, and may be broken during use to make it unusable. Conversely, if the grammage exceeds 80 g / m ² , the rigidity of the nonwoven fabric increases, making it difficult to use, and the water disintegratability when the water disintegratable nonwoven fabric is put into a water stream tends to be poor.

These regenerated cellulose fibers, wood pulp
Such a mixture is used as a raw material to form a web by wet papermaking on a paper machine appropriately selected from a round paper machine, a short wire machine, an inclined wire paper machine, a fourdrinier paper machine, etc. A water entanglement method by jetting is applied.

As a method for obtaining substantially the same effect as the present invention ,
Identify reactive sizing agents when forming webs on paper machines
There is also a method of adding an amount . In this case, the mixture of the regenerated cellulose fiber and wood pulp is suspended in water to form a slurry, and the reactive sizing agent is added as a raw material, and the paper is wet-formed in the paper machine. Dry with a dryer to form a web.

The reactive sizing agent to be added includes alkyl ketene dimer, alkenyl succinic anhydride, fatty acid anhydride,
One type selected from isocyanate aziridine derivatives and the like. In particular, even when wood pulp having a Runkel ratio not in the above range is used, by adding these reactive sizing agents, water disintegration and wet strength can be made characteristics having no practical problems.

The amount of the reactive sizing agent to be added is from 0.3 to 0.3 per absolute dry weight of the regenerated cellulose fiber and wood pulp.
2.0% by weight. If the addition amount is less than 0.3% by weight,
The effect is not exhibited because the amount of the reactive sizing agent with respect to the fiber is too small. Water disintegration improves as the amount added increases. However, if the addition amount exceeds 2.0% by weight, the bonding strength becomes too weak, the wet strength of the nonwoven fabric is reduced, and tearing occurs during use. In addition, reactive sizing agents are expensive and unsuitable for increasing product costs.

The regenerated cellulose fiber and wood pulp are suspended in water to form a slurry, a reactive sizing agent is added to the slurry to form a papermaking raw material, and a wet web is formed in the known papermaking machine. To dry web. The drying temperature is the temperature at which the reactive sizing reacts and binds with the wood pulp, e.g.
The temperature may be 130 ° C.

In the present invention, the Runkel ratio is 0.35
Instead of using wood pulp of ~ 0.55, the use of softwood bleached pulp having an α-cellulose content of 85-88% by weight and preferably a Canadian standard freeness of 550-750 ml CSF instead of wood pulp. The water-disintegrable nonwoven fabric according to the invention can be obtained.

JIS P used in the present invention
85-88% by weight of α-cellulose measured according to 8101
Wood pulp is obtained from coniferous wood. When cooking the wood, the cooking degree is advanced to lower the kappa number of the pulp, and the hunter pulp brightness is increased to 85 to 93% by multi-stage bleaching, and the hemicellulose and lignin are sufficiently reduced. It has been removed.

When wood pulp containing less than 85% by weight of α-cellulose is used, the bonding strength between fibers becomes stronger, and the water dissolvability of the obtained nonwoven fabric tends to be poor. Although the resulting water-disintegratable nonwoven fabric is weak in bonding and has excellent water-disintegration properties, the wet strength of the nonwoven fabric tends to be low. The Runkel ratio and the content of α-cellulose are irrelevant, but both conditions may fall within the required range, resulting in a preferred wood pulp. However, when the content of α-cellulose is in the above range, a nonwoven fabric having satisfactory water-degradability and wet strength can be obtained.

As described above, the freeness is 550 ml CF
If it is less than S, the bonding strength between the pulp fibers is increased, and the wet strength of the nonwoven fabric is increased, but the water disintegration is deteriorated, which is not suitable. The regenerated cellulose fiber and the wood pulp having the α-cellulose content are formed into a slurry as a papermaking raw material, and a web is formed in a known papermaking machine. Thereafter, as described above, a hydroentanglement method by jetting a high-pressure water jet is applied.

The water-disintegrable nonwoven fabric of the present invention thus obtained can have a water-disintegrability of 300 seconds or less. The water-disintegration property is as follows: a water-disintegratable nonwoven fabric having a size of 5 cm square is put into 100 ml of pure water, shaken at a shaking speed of 300 cycles / minute, and the water-disintegratable nonwoven fabric is disintegrated in water. It was expressed as the time required to defibrate until the water became about 1 cm ² . If the water disintegration is longer than 300 sec, the nonwoven fabric becomes difficult to disintegrate in running water, and is likely to become a cause of pipe clogging when flushed in a toilet or the like, which is not suitable. The shorter the water disintegration is, the more preferable it is. However, the value of the water disintegration achieved while maintaining the strength of the nonwoven fabric is naturally limited, and is about 60 seconds at the shortest.

The water-disintegratable nonwoven fabric according to the present invention
The average expressed by the formula (1) of the wet tensile strength measured according to ISP 8135 can be set to 0.2 kgf / 25 mm or more and 1 kgf / 25 mm or less. Average wet tensile strength = (XY) ^1/2 (1) X: longitudinal wet tensile strength of water-disintegratable nonwoven fabric Y: horizontal wet tensile strength of water-disintegrable nonwoven fabric

The water-disintegratable nonwoven fabric has a strength of 0.2 kgf / 25.
If it is less than mm, it is not suitable because it is likely to be broken during actual use. In using the water-disintegratable nonwoven fabric, if the average of the wet tensile strength is 0.2 kg / 25 mm or more, it can be used without any practical problem, and the higher the average of the wet tensile strength, the more difficult it is to break. When produced by the method according to the present invention, the upper limit of the wet strength value when the water disintegration is 300 sec or less is about 1.0 kgf / 25 mm. In the present invention, a water-disintegratable nonwoven fabric having both wet strength and water-disintegration properties that can be practically used can be obtained by confounding and integrating the above-mentioned raw materials. 0.07 to 0.20 kW
By hydroentanglement under the conditions of h / kg,
Excellent water disintegration and wet strength can be more easily imparted.

In order to use the water-disintegratable nonwoven fabric according to the present invention as a wet product such as a wet tissue, a wiping wipe, or a wiper, if necessary, wetting agents such as water and propylene glycol, alcohols and parabenzoic esters, etc. Various agents such as antibacterial, fungicide, fragrance, and components having a specific medicinal effect can be impregnated alone or in combination. Further, when the water-disintegratable nonwoven fabric according to the present invention is used as a surface material such as a sanitary material, it can be used as it is, but the nonwoven fabric may be subjected to a treatment for enhancing hydrophilicity and water repellency as desired.

As described above, the water-disintegratable nonwoven fabric according to the present invention has a strength that can withstand operations such as cleaning in a dry state and a wet state, and forms a nonwoven fabric in a large amount of water flow. The fibers can be disintegrated, and can be suitably used as a wet product such as a wet tissue, a cloth, a cleaning wiper, or a top sheet of a disposable diaper or a sanitary napkin, and is easily disintegrated after use by a large amount of water flow in a toilet or the like. It is something that can be done.

[0067]

The present invention will be described in more detail with reference to the following examples, which, of course, are not intended to limit the present invention. In Examples and Comparative Examples, “%” means “% by weight” unless otherwise specified.

Example 1 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, an L / D: 594 of 30% rayon fiber and a Runkel ratio of 0.44 (Canadian standard freeness : 720
Using a 70% raw material as a raw material, a wet papermaking web is formed using an inclined wire paper machine, and then dried, and the basis weight is 50 g.
/ M ² of rayon / pulp mixed paper.

The sheet was placed on a transfer support net formed of a 50-mesh wire net, and then the sheet was
While transferring at a speed of m / min, a high-pressure water column flow is jetted at a water pressure of 75 kg / cm ² using a high-pressure water column flow treatment device in which nozzle holes having a hole diameter of 0.15 mm are arranged at 1.0 mm intervals. After being subjected to a flow treatment, it was dried to obtain a water-disintegrable nonwoven fabric. The additional specific energy imparted to the sheet by this high-pressure water column flow treatment was 0.11 kWh / kg.

The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the following evaluation method. 1. Wet tensile strength (kg / 25 mm) Measured according to JIS P 8135 with the width of the test piece set to 25 mm. 2. Average of Wet Tensile Strength (kg / 25 mm) From the wet tensile strength measured at 1, an average was determined by the formula (1). Average wet tensile strength = (XY) ^1/2 (1) X: longitudinal wet tensile strength of water-disintegratable nonwoven fabric Y: horizontal wet tensile strength of water-disintegrable nonwoven fabric

3. Water decomposability (sec) A water decomposable nonwoven fabric having a size of 5 cm × 5 cm square is prepared.
Put 100 ml of pure water into a 150 ml Erlenmeyer flask,
The water disintegratable nonwoven fabric is put into a flask and shaken at a speed of 3
00 cycles / min, reciprocating shaking with shaking width 25mm,
Shaking is stopped every 30 seconds, the disintegration state of the water-disintegratable nonwoven fabric is observed, and the shaking is repeated. The time required for defibration until the size of the largest piece of the water-disintegratable nonwoven fabric became about 1 cm ² was defined as a water-disintegrable value (sec) and represented by an average value of n = 5. It can be said that the water disintegration is excellent if it is 300 sec or less.

4. Texture (points) The texture was determined by a tactile test by 20 monitors.
In the test method, the water-disintegratable nonwoven fabric was gripped by hand, and expressed as a total score (perfect score of 100) per monitor based on the following evaluation criteria. If the total score is 75 points or more, it can be said that the texture is good. 5 points: Very good feel 4 points: Excellent feel 3 points: Normal feel 2 points: Somewhat poor feel 1 point: Poor feel 0 points: Very poor feel

Example 2 Fineness: 3.0 d, fiber length: 5 mm, L / D: 300
-Softwood with 50% runon fiber and Runkel ratio: 0.50
Using bleached kraft pulp with a beater, Canadian standard filtered water
Degree: 50% pulp beaten to 600ml
As a raw material, wet papermaking using a tilted wire paper machine
After forming a web, it is dried and has a basis weight of 65 g / m. ^TwoRayon
/ Pulp mixed paper.

The sheet was placed on a transfer support net formed of a 50-mesh wire net, and then the sheet was
While transferring at a speed of m / min, a hole diameter of 0.15 mm
Using a high-pressure water column flow treatment device in which the nozzle holes are arranged at 1.0 mm intervals, a high-pressure water column flow is jetted at a water pressure of 90 kg / cm ² , subjected to a high-pressure water column flow treatment, and dried to obtain a water-disintegratable nonwoven fabric. Was. The additional specific energy imparted to the sheet by this high-pressure water column flow treatment was 0.17 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Example 3 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 10 mm, a rayon fiber of L / D: 849 of 20% and a Runkel ratio of 0.47 (Canadian standard freeness : 68
0 ml) as a raw material, forming a wet papermaking web using an inclined wire-type paper machine, and then drying and drying the web.
² rayon / pulp mixed paper was obtained.

This sheet was formed with an 80 mesh wire mesh.
On the transporting support net, and then put the sheet
While transferring at a speed of m / min, a hole diameter of 0.15 mm
High pressure water column flow treatment with nozzle holes arranged at 1.0mm intervals
30kg / cm using the device ^TwoHigh pressure water column flow with water pressure
After spraying, subjecting to high pressure water column treatment and drying,
A woven fabric was obtained. This high pressure water column flow treatment gives the sheet
The added specific energy was 0.08 kWh / kg.
Was. The obtained water-disintegratable nonwoven fabric was evaluated in the same manner as in Example 1.
The quality was evaluated by the method.

Example 4 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, an L / D: 594 of 30% rayon fiber and a Runkel ratio of 0.55 (Canadian standard freeness : 650
ml) as raw materials, using a tilted wire type paper machine, wet-making the paper, dehydrating with a subsequent press roll at a linear pressure of 3 kg / cm, and forming a wet paper web having a moisture content of 68%. Immediately after subjecting the wet papermaking web to high-pressure water column treatment with the high-pressure water column treatment device installed immediately afterwards,
After drying, a rayon / pulp mixed paper having a basis weight of 50 g / m ² was obtained. The support of the high-pressure water column flow treatment device is formed of an 80-mesh wire net, and the wet papermaking web is 20 m / mi.
While transferring at a speed of n, a high-pressure water column stream is jetted at a water pressure of 40 kg / cm ² by using a high-pressure water column flow treatment device in which nozzle holes having a hole diameter of 0.15 mm are arranged at 1.0 mm intervals,
A high pressure water column treatment was applied and treated. The added specific energy given to the sheet by this high-pressure water column flow treatment is 0.1%.
It was 0 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

REFERENCE EXAMPLE 1 A softwood bleached kraft pulp (Tasman) beaten to 20% rayon fiber having a fiber length of 10 mm, a fineness of 3.0 denier and a diameter to fiber length ratio of L / D of 600 and a Canadian standard freeness of 600 ml CSF M-90, Tasman Pulp and Paper
Company, Tree species: Radiata Pine, Runkel ratio: 0.33) 80%
And carboxymethylated fiber (trade name: Kikkolate, manufactured by Nichirin Chemical Co., Ltd., degree of substitution: 0.4, carboxylic acid type carboxymethyl group: 20%) based on the absolute dry weight of the mixture. As a raw material for papermaking, papermaking was performed using a tilted wire paper machine to form a wet web, and then dried to obtain a dry web made of rayon, pulp and carboxymethylated fiber having a basis weight of 50 g / m ² .

This web was placed on a conveyor of a transfer support net made of an 80-mesh wire net, and nozzles having a hole diameter of 0.15 mm were arranged at 1.0 mm intervals while being transferred at a speed of 40 m / min. Using a high-pressure water jet flow treatment device, a high-pressure water jet was jetted from above the web at a water pressure of 90 kg / cm ² , and then dried with a hot-air dryer at a temperature of 130 ° C to obtain a water-disintegratable nonwoven fabric. The additional specific energy imparted to the web by this high-pressure water jet treatment was 0.17 kWh / kg.

Reference Example 2 50% rayon fiber having a fiber length of 7 mm, a fineness of 1.5 denier and an L / D of 594, and a Canadian standard freeness of 700 ml CF
Softwood bleached kraft pulp (Tasman M-90, T
Made by asman Pulp and Paper, Tree species: Radiata Pine, Runkel ratio: 0.33) Mixture with 50% 11 per absolute dry weight
% Of carboxymethylated fiber (trade name: Kikkolate, manufactured by Nichirin Chemical Co., degree of substitution: 0.4, carboxylic acid type carboxymethyl group: 20%) as a raw material, and a web is formed on an inclined wire paper machine. Was formed and dried to obtain a nonwoven fabric made of rayon and pulp having a basis weight of 65 g / m ² .

The nonwoven fabric was placed on a transfer support net formed of a 50-mesh wire net, and then transferred at a speed of 30 m / min.
Using a high-pressure water jet stream treatment device arranged at 0 mm intervals, a high-pressure water jet stream was jetted from above the nonwoven fabric at a water pressure of 90 kg / cm ² , and then dried to obtain a water-disintegratable nonwoven fabric. The additional specific energy imparted to the nonwoven fabric by this high-pressure water jet treatment was 0.17 kWh / kg.
The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Reference Example 3 The fineness was 1.5 denier, the fiber length was 10 mm, and the L / D was 8
49% rayon fiber 20%, unbeaten softwood bleached kraft pulp (Canada standard freeness: 720 ml CSF, Laj
a, Cia. Manufacturera de Papeles, Tree species: Radiat
a Pine, Runkel ratio: 0.33) An alkyl ketene dimer (product number AS262, manufactured by PMC Japan, solid content concentration: 20%) was used as a reactive sizing agent in a raw material slurry comprising a mixture of 80% and a fiber content of 80%. After adding 1.8% by dry weight, a web was formed on an inclined wire paper machine and then dried to obtain a nonwoven fabric consisting of rayon and pulp having a basis weight of 60 g / m ² .

This sheet was placed on a transfer support net formed of a 80-mesh wire net, and then transferred at a speed of 40 m / min.
Using a high-pressure water jet flow treatment device arranged at 0 mm intervals, a high-pressure water jet flow was jetted at a water pressure of 60 kg / cm ² , and then dried to obtain a water-disintegratable nonwoven fabric. The additional specific energy imparted to the nonwoven fabric by this high-pressure water jet treatment was 0.08 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Reference Example 4 A hydrolyzable nonwoven fabric was obtained in the same manner as in Reference Example 3 , except that the addition of the alkyl ketene dimer was 0.5%.

Example 9 The fineness was 1.5 denier, the fiber length was 7 mm, and the L / D was 59.
30% rayon fiber and α-cellulose content of 8
Softwood bleached kraft pulp adjusted to digestion and bleaching conditions to 6.5% (Canada standard freeness: 600 m
Using a raw material slurry composed of a mixture of 1CSF, 70%), a web is formed in an inclined wire-type paper machine, and the web is dewatered with a press roll at a linear pressure of 3 kg / cm. After the web was formed, the web was subjected to high-pressure water jet flow treatment by a high-pressure water jet flow treatment device installed immediately after the press rolls, and then dried to obtain a water-disintegrable material consisting of rayon and pulp having a basis weight of 50 g / m ² . A non-woven fabric was obtained.

The support of the high-pressure water jet flow treatment device is 80
It is formed of a mesh wire mesh, and the web is 20 m /
A high-pressure water jet stream was jetted at a water pressure of 40 kg / cm ² using a high-pressure water jet stream processing apparatus in which nozzle holes having a hole diameter of 0.15 mm were arranged at 1.0 mm intervals while being transferred at a speed of 1 minute. The additional specific energy imparted to the nonwoven fabric by this high pressure water jet treatment is 0.10 kWh / k.
g. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Example 10 Unbeaten softwood bleached with 7% fiber length, 1.5 denier fineness, 50% rayon fiber having an L / D of 594, and digestion conditions and bleaching conditions adjusted to have an α-cellulose content of 85.9%. Kraft pulp 50% (Canada standard freeness: 640
ml CFS) as a raw material, forming a web in an inclined wire-type paper machine, drying the web, and weighing 65 g.
/ M ² of non-woven fabric consisting of rayon and pulp.

The nonwoven fabric was placed on a transfer support net formed of a 50-mesh wire net, and then transferred at a speed of 30 m / min.
Using a high-pressure water jet stream treatment device arranged at 0 mm intervals, a high-pressure water jet stream was jetted from above the nonwoven fabric at a water pressure of 90 kg / cm ² , and then dried to obtain a water-disintegratable nonwoven fabric. The additional specific energy imparted to the nonwoven fabric by this high-pressure water jet treatment was 0.17 kWh / kg.
The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Comparative Example 1 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, an L / D: 594 of 40% rayon fiber and a Runkel ratio of 0.33 (Canadian standard freeness : 720
ml) as a raw material to form a wet papermaking web using an inclined wire paper machine, followed by drying and drying.
A g / m ² rayon / pulp mixed paper was obtained.

The sheet is placed on a transfer support net formed of an 80 mesh wire mesh, and then the sheet is
While transferring at a speed of m / min, a hole diameter of 0.15 mm
Using a high-pressure water column flow treatment device in which the nozzle holes are arranged at 1.0 mm intervals, a high-pressure water column flow is jetted at a water pressure of 50 kg / cm ² , subjected to high-pressure water column treatment, and dried to obtain a water-disintegratable nonwoven fabric. Was. The additional specific energy imparted to the sheet by this high pressure water column flow treatment was 0.10 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Comparative Example 2 Unbeaten softwood bleached kraft pulp having a fineness of 8 d, a fiber length of 10 mm, a rayon fiber having an L / D of 367 of 40% and a Runkel ratio of 0.43 (Canada standard freeness: 720 m)
l) was used as a raw material, and a wet papermaking web was formed using an inclined wire paper machine, followed by drying, and a basis weight of 50 g.
/ M ² of rayon / pulp mixed paper.

The sheet was placed on a transfer support net formed of an 80 mesh wire mesh, and then the sheet was
While transferring at a speed of m / min, a hole diameter of 0.15 mm
Using a high-pressure water column flow treatment device in which the nozzle holes are arranged at 1.0 mm intervals, a high-pressure water column flow is jetted at a water pressure of 50 kg / cm ² , subjected to high-pressure water column treatment, and dried to obtain a water-disintegratable nonwoven fabric. Was. The additional specific energy imparted to the sheet by this high pressure water column flow treatment was 0.10 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Comparative Example 3 Unbeaten softwood bleached kraft pulp having a fineness of 1.0 d, a fiber length of 5 mm, 40% rayon fiber having an L / D of 735, and a Runkel ratio of 0.43 (Canadian standard freeness : 520
ml) as a raw material to form a wet papermaking web using an inclined wire paper machine, followed by drying and drying.
A g / m ² rayon / pulp mixed paper was obtained.

The sheet was placed on a transfer support net formed of an 80 mesh wire mesh, and then the sheet was
While transferring at a speed of m / min, a hole diameter of 0.15 mm
Using a high-pressure water column flow treatment device in which the nozzle holes are arranged at 1.0 mm intervals, a high-pressure water column flow is jetted at a water pressure of 50 kg / cm ² , subjected to high-pressure water column treatment, and dried to obtain a water-disintegratable nonwoven fabric. Was. The additional specific energy imparted to the sheet by this high pressure water column flow treatment was 0.10 kWh / kg. The quality of the obtained water-disintegratable nonwoven fabric was evaluated by the same evaluation method as in Example 1.

Example 11 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, an L / D: 594 of 30% rayon fiber and a Runkel ratio of 0.44 (Canadian standard freeness) : 720
Using a 70% raw material as a raw material, a wet papermaking web is formed using an inclined wire paper machine, and then dried, and the basis weight is 50 g.
/ M ² of rayon / pulp mixed paper.

This sheet was formed with a 50 mesh wire mesh.
On the transporting support net, and then put the sheet
While transferring at a speed of m / min, a hole diameter of 0.15 mm
High pressure water column flow treatment with nozzle holes arranged at 1.0mm intervals
75kg / cm using the device ^TwoHigh pressure water column flow with water pressure
After spraying, subjecting to high pressure water column treatment and drying,
A woven fabric was obtained. This high pressure water column flow treatment gives the sheet
The added specific energy was 0.26 kWh / kg.
Was. The obtained water-disintegratable nonwoven fabric was evaluated in the same manner as in Example 1.
The quality was evaluated by the method.

Example 12 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, a rayon fiber of L / D: 594 of 30% and a Runkel ratio of 0.44 (Canadian standard freeness : 720
Using a 70% raw material as a raw material, a wet papermaking web is formed using an inclined wire paper machine, and then dried, and the basis weight is 50 g.
/ M ² of rayon / pulp mixed paper.

This sheet was formed with a 50 mesh wire mesh.
On the transporting support net, and then put the sheet
While transferring at a speed of m / min, a hole diameter of 0.15 mm
High pressure water column flow treatment with nozzle holes arranged at 1.0mm intervals
20kg / cm using the device ^TwoHigh pressure water column flow with water pressure
After spraying, subjecting to high pressure water column treatment and drying,
A woven fabric was obtained. This high pressure water column flow treatment gives the sheet
The added specific energy was 0.04 kWh / kg.
Was. The obtained water-disintegratable nonwoven fabric was evaluated in the same manner as in Example 1.
The quality was evaluated by the method.

Comparative Example 4 Unbeaten softwood bleached kraft pulp having a fineness of 1.5 d, a fiber length of 7 mm, an L / D: 594 of rayon fiber of 5% and a Runkel ratio of 0.44 (Canadian standard freeness) : 720m
l) Using 95% as a raw material, a wet papermaking web is formed using an inclined wire paper machine and then dried, and the basis weight is 50 g /
A rayon / pulp mixed paper of m ² was obtained.

This sheet was formed with a 50 mesh wire mesh.
Placed on a transfer support net, and then put the sheet
While transferring at a speed of m / min, a hole diameter of 0.15 mm
High pressure water column flow treatment with nozzle holes arranged at 1.0mm intervals
75kg / cm using the device ^TwoHigh pressure water column flow with water pressure
After spraying, subjecting to high pressure water column treatment and drying,
A woven fabric was obtained. This high pressure water column flow treatment gives the sheet
The added specific energy was 0.11 kWh / kg.
Was. The obtained water-disintegratable nonwoven fabric was evaluated in the same manner as in Example 1.
The quality was evaluated by the method.

Comparative Example 5 A water-disintegratable nonwoven fabric was obtained in the same manner as in Example 5 except that the compounding ratio of the carboxymethylated fiber was changed to 1%, and the same evaluation was performed.

Comparative Example 6 A water-disintegratable nonwoven fabric was obtained in the same manner as in Example 5 except that the compounding ratio of the carboxymethylated fiber was changed to 20%, and the same evaluation was performed.

Comparative Example 7 A water-disintegratable nonwoven fabric was obtained in the same manner as in Example 7 except that the addition ratio of the alkyl ketene dimer was changed to 2.5%.

Comparative Example 8 In Example 9, unbeaten softwood bleached kraft pulp containing 90.0% of α-cellulose (Canada standard freeness: 640 m)
A water-disintegratable nonwoven fabric was obtained in the same manner as in Example 9 except that (ICSF) was used, and the evaluation was performed in the same manner.

Comparative Example 9 In Example 9, softwood bleached kraft pulp in which digestion conditions and bleaching conditions were adjusted so as to have an α-cellulose content of 83.5% was used, and a Canadian standard freeness was 600 ml CSF using a beater. A water-disintegratable non-woven fabric was obtained in the same manner as in Example 9 except that the pulp was beaten until the evaluation was performed. Table 1 shows the quality of the water-disintegrable nonwoven fabric according to the examples and the comparative examples.

[0106]

[Table 1]

As can be seen from Table 1, the water-disintegratable nonwoven fabric according to the present invention has an excellent balance between wet tensile strength and water-disintegration, and has a good hand. On the other hand, when a pulp having a too low Runkel ratio is used (Comparative Example 1), the strength and the texture are good, but the entanglement of the pulp fiber or the regenerated cellulose fiber by the high-pressure water column flow treatment is too strong, and the water disintegration is poor. Run short. When the fiber diameter of the regenerated cellulose fiber is too large (Comparative Example 2), the fibers are not sufficiently entangled even after high-pressure water column flow treatment, and only a sheet having low strength is obtained. When the freeness of the pulp to be used is too low (Comparative Example 3), the fiber entanglement due to the high pressure water column flow treatment becomes too strong, resulting in poor water disintegration, and the cost of the fiber itself is high. The price will be high.

When the blending ratio of the regenerated cellulose fibers is too low (Comparative Example 4), the fiber entanglement is not sufficient, and the strength of the obtained sheet is low. When the amount of the carboxymethylated fiber is too small (Comparative Example 5), the texture is good and the wet tensile strength is strong, but the bond is strong, so that it is not easily disaggregated into water and the water dissolvability is insufficient. Conversely, when the amount of the carboxymethylated fiber is too large (Comparative Example 6),
Excellent water disintegration, but low wet strength and good texture
It will be bad . When the addition amount of the reactive sizing agent is too large (Comparative Example 7), the binding strength is too weak due to the reactive sizing agent, and the water dissolvability is very excellent, but the wet tensile strength is too weak.

When a pulp having too high α-cellulose content was used (Comparative Example 8), the bonding strength of the wood pulp was too weak,
The wet tensile strength is too weak to be suitable. Conversely, when pulp having too low α-cellulose content is used (Comparative Example 9),
Although sufficient wet tensile strength can be obtained, the bonding strength of the wood pulp is too strong, the water disintegration is poor, and it cannot be put to practical use.

[0110]

Industrial Applicability The present invention reduces the content of expensive regenerated cellulose fibers, maintains strength enough to withstand operations such as cleaning in a dry state and a wet state, and forms a nonwoven fabric in a large amount of water flow. The present invention provides an effect of providing a water-disintegratable nonwoven fabric whose constituent fibers can be easily disintegrated and a method for producing the same.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI A47K 10/16 A47K 10/16 C A47L 13/16 A47L 13/16 A A61F 13/15 A61K 7/50 13/472 D21H 11/00 13 / 511 15/00 13/551 A61F 13/18 A61K 7/50 310Z D21H 11/00 383 15/00 (56) References JP-A-1-97300 (JP, A) JP-A-6-65852 (JP, A JP-A-1-207457 (JP, A) JP-A-7-54255 (JP, A) JP-A-9-49188 (JP, A) JP-A-9-49198 (JP, A) 8897 (JP, A) JP-A-7-1216781 (JP, A) JP-A-6-200497 (JP, A) Japan Association of Paper and Pulp Technology, Handbook of Paper and Pulp Technology 1982, Miyoshi Printing Co., Ltd., Japan, October 1982 1st, 9-10 (58) Field surveyed (Int. Cl. ⁷ , DB name) D04H 1/00-18/00 D21H 11/00-27/42

Claims (2)

(57) [Claims] 1. A non-woven fabric in which regenerated cellulose fibers and wood pulp are entangled and integrated, wherein the non-woven fabric comprises: (a) a regenerated cellulose fiber having a fineness of 1.0 to 5.0 deniers;
Regenerated cellulose fiber with 55 wt% and Runkel ratio of 0.35 to 0.55 and freeness of 85 to 45 wt% of wood pulp with 550 to 750 ml CSF or (d) fineness of 1.0 to 5.0 denier A wood pulp containing 15 to 55% by weight and an α-cellulose content of 85 to 88% by weight or 85 to 45% by weight, and a composition of at least one of 5 cm × 5 cm (25 cm ² ). The non-woven fabric
When put into 00 ml of pure water and shaken at a shaking speed of 300 cycles / min and disintegrated in water, the water disintegration expressed by the time required for disintegration until the maximum piece size becomes 1 cm ² is After 60 to 300 seconds, the JIS P81
The value of the geometric average of the wet tensile strength measured in accordance with No. 35 expressed by the following formula (1) is 200 to 1000 gf / 25 mm.
A water-disintegratable nonwoven fabric, characterized in that: Geometric average of wet tensile strength = (XY) ^1/2 (1) where X is the wet tensile strength in the longitudinal direction of the water-disintegratable nonwoven fabric (g)
f / 25 mm), Y: lateral wet tensile strength of water-disintegratable nonwoven fabric (gf / 25)
mm). 2. A web is formed by a known wet papermaking method using any of the raw materials constituting the water-disintegratable nonwoven fabric according to claim 1, and then the web is placed on a perforated support.
(2) The addition specific energy E represented by the equation is 0.07 to
A high-pressure water jet stream is jetted on the web surface under the condition of 0.20 kWh / kg, and the regenerated cellulose fiber and the wood pulp are entangled and integrated by a water entanglement method to obtain the nonwoven fabric.
Method of producing a water-decomposable non-woven fabric, characterized in that that. E = (A × (2 / ρ) ^1/2 × (g × P) ^3/2 ) / (M × 60 × S) (2) where A is the sum of the nozzle hole areas (m ² / m) E: Additional specific energy (kWh / kg) ρ: Water density (kg / cm ³ ) g: Gravitational acceleration (m / s ² ) P: Water pressure at nozzle part (Pa) S: Web passing speed (m / Min) M: Web mass (g / m ² ).