JPH09228214A - Water disintegrating nonwoven fabric and method for producing the same - Google Patents

Abstract

(57) Abstract: A water-disintegratable non-woven fabric, which has a sufficient strength in a wet state with a liquid, retains a sheet shape, and extremely quickly and easily disintegrates into a fibrous form when contacted with a large amount of water, Providing a manufacturing method thereof. SOLUTION: A water-disintegratable non-woven fabric composed of regenerated cellulose fibers having a fiber length of 4 to 20 mm and pulp fibers is entangled with each other by a high-pressure water jet flow treatment.
8135 has a wet strength of 100-800.
It is gf / 25 mm. 40 to 85% by weight of regenerated cellulose fiber having a fiber length of 4 to 20 mm, and JISP 8121
According to Canadian Standard Freeness of 100-550 ml CSF pulp fibers 15-60% by weight are mixed, after forming a web using the resulting mixture, the web is placed on a transfer conveyor made of net, A jet of high pressure water is then jetted through one or both sides of the web to entangle the fibers and dry. The high-pressure jet flow has an additional specific energy in the range of 0.1 to 0.6 kWh / kg per one side.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-disintegratable nonwoven fabric and a method for producing the same. More specifically, the present invention is a sheet-shaped non-woven fabric composed of fibers in a web composed of non-continuous regenerated cellulose fibers and pulp fibers entangled by a water entanglement method, in a wet state when used. Although it has sufficient bond strength even in the above, the web structure collapses due to a large amount of water flow, which is suitable for wet tissues, cleaning wipers, diapers, sanitary napkins, etc., and its sheet structure is extremely easily destroyed by a large amount of water. The present invention relates to a nonwoven fabric that is dispersed and dispersed and a method for manufacturing the same.

[0002]

2. Description of the Related Art In general, sanitary items, wet tissues and the like are currently disposed of as waste after use. Especially, in the case of disposable diapers, when the excrement at the time of use is faeces, the disposal method is to remove the disposable diaper from the user.
It is very troublesome and inconvenient because the disposable diaper is taken to the toilet and only the stool is removed and discarded, after which the remaining disposable diaper is disposed of as ordinary garbage. Also, for young children, most of the stools are loose stools, which makes it difficult to remove them from the paper diaper.
The stool is not completely removed, but is disposed of together with general combustible waste, which is very unsanitary. Also, sanitary products, wet tissues, wipers for cleaning flush toilets, and the like are similar, and their disposal methods are difficult.

Therefore, it has been conventionally proposed to use a water-disintegrating nonwoven fabric as a wet tissue or as a top sheet for sanitary goods. At this time, the water-disintegratable non-woven fabric that can be used as a wet tissue or a top sheet of a disposable diaper is in a wet state during its use, so that it can be used in a dry state as well as in a sheet-like web structure while maintaining a sheet-like web structure. Two properties are required that are well tolerated and that with a large amount of water, very little force causes the web configuration to collapse to the original fiber shape. Many of the so-called water-disintegratable nonwoven fabrics today contain a water-soluble substance as an adhesive in a part of the nonwoven fabric. However, when such a non-woven fabric is used as a wet tissue or a top sheet of a disposable diaper, a water-soluble substance is eluted in a wet state, which not only impairs the feel during use, but also cannot maintain a sheet-like web structure.

Japanese Patent Application Laid-Open No. 1-207457 discloses a sanitary sheet composed of 30% by weight or more of fibers which are carboxymethylcellulose having a carboxymethyl group substitution degree of 0.25 to 0.4 and are soluble in an alkaline solution. Is disclosed. This sheet is a disposable diaper, a surface material for sanitary napkins, a so-called liner laid on the surface of the diaper,
Used for pet sheets, this sanitary sheet contains less than 30% by weight of a second fiber composed of polyester, polypropylene, rayon, polyester-polyethylene composite fiber, etc. It is possible to carry out a down-flow treatment into a flush toilet with an alkaline solution such as sodium hydroxide, ammonia, sodium silicate and the like. However, it is dangerous to always use a deleterious substance such as the alkaline solution in a general household and to use it, and it is inconvenient to flush the alkaline solution after each downflow treatment.

[0005] Japanese Patent Laid-Open No. 216889/1992 discloses that a short fiber such as a natural fiber having a fineness of 0.5 to 10 denier and a fiber length of 31 mm or less, a regenerated cellulose fiber or a synthetic fiber is dissolved in physiological saline (Y). Disclosed is a water-disintegratable non-woven fabric in which a binder having a dissolution property such that the ratio of dissolution time (X) to tap water is Y / X = 0.5 to 1.5 is bonded at 3 to 50% by weight based on the short fibers. Has been done. Such a water-disintegratable nonwoven fabric is difficult to dissolve in tap water and body fluids,
Although it is easily dissolved in sewage, it takes 1 to 30 hours to dissolve the binder used and disintegrate the non-woven fabric, and therefore the used non-woven fabric cannot be immediately washed down with a flush toilet.

On the other hand, JP-A-6-101154 discloses a polyester or polyolefin fiber sheet containing 0.1 to 10% by weight of a cellulose derivative which is soluble in an organic solvent and soluble or dispersible in water. A water-disintegratable non-woven fabric, and further, this water-disintegrable property was used above and below, and an absorbent layer made of a pulp fiber sheet containing a superabsorbent polymer and a film made of a thermoplastic water-soluble polyvinyl alcohol were provided therebetween. A water disintegrable nonwoven laminate is disclosed. However, when the cellulose-based derivative contained in the polyester or polyolefin fiber sheet comes into contact with a liquid, the water-soluble one easily dissolves and comes into contact with human skin, and the water-dispersible one hardly fixes the fiber sheet. There is a problem.

JP-A-6-126901 discloses a water-disintegratable non-woven fabric obtained by heating and adhering a film made of polyvinyl alcohol to a polyester or polyolefin fiber sheet, and the water-disintegratable non-woven fabric having pinholes on the entire surface thereof. Disclosed is a water-disintegratable nonwoven fabric laminate obtained by laminating a pulp fiber sheet having a superabsorbent polymer between water-disintegrable nonwoven fabrics and heating and adhering the periphery. Further, in JP-A-6-134910, a water-disintegratable non-woven fabric obtained by adhering a film made of polyvinyl alcohol having pores substantially all over the polyester or polyolefin fiber sheet, and the above-mentioned water-disintegratable non-woven fabric, A pulp fiber sheet containing a super-absorbent polymer is laminated between a polyester or polyolefin fiber sheet and a film obtained by adhering a film made of polyvinyl alcohol having substantially no pores, and the periphery is adhered. A water disintegrable nonwoven laminate is disclosed. However, even if a film made of the water-soluble polyvinyl alcohol is adhered to one side of polyester or polyolefin fiber, the film has a weak force to hold the sheet shape. However, if the fiber sheet is made of long fibers, the sheet is unlikely to be completely collapsed by the water flow of the flush toilet, and the flush pipe of the toilet is clogged.

Techniques for applying a high-pressure water jet stream (hydraulic entanglement) to a sheet-like mixture of wood pulp and synthetic fibers having a specific length are known. Japanese Patent Laid-Open No. 2-145841
Japanese Unexamined Patent Publication (Kokai) No. Hei 10 (1999) -101 is a highly absorbent non-woven fabric having a basis weight of 100 g to 267 g per 1 m ² and containing no added bonding agent,
Basically, based on the dry weight of the fibers, it consists of 50-75% by weight of wood pulp and 50-25% by weight of staple synthetic fibers, which are uniformly mixed with one another in one wet laid web and consolidated. Discloses a highly absorbent nonwoven fabric that is hydraulically entangled under sufficient energy to form a highly absorbent fabric. However, this non-woven fabric absorbs water very like a cloth and has very good wet strength, but it has a high entanglement strength between fibers due to compaction,
Since the sheet structure is not easily destroyed even with a large amount of water, it cannot be used as a water-disintegrating nonwoven fabric.

[0009]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have found that regenerated cellulose fibers maintain a sheet shape in a wet state and disintegrate into a fibrous form extremely quickly and easily when brought into contact with a large amount of water. A non-woven fabric composed of a pulp fiber and a pulp fiber and a method for manufacturing the same were intensively studied. As a result, the inventors of the present invention form a web without using any adhesive when producing a non-woven fabric, and therefore a non-continuous regenerated cellulose fiber having a specific fiber length and a freeness within a specific range. Mixed with pulp fibers having a, to form a web by wet papermaking using this mixture, then place the web on a transfer conveyor having a running woven structure consisting of wire netting, plastic netting, etc., The non-woven fabric obtained after the fibers are entangled with each other by jetting a high-pressure water jet with a specific range of additional specific energy on one side of the web or on both the front and back sides, has excellent wet strength and is wet with liquid. Although the sheet-like morphology was maintained to some extent, it was found that the structure was extremely easily destroyed when immersed in a large amount of water, and was quickly dispersed, thus completing the present invention. An object of the present invention is to provide a water-disintegratable non-woven fabric which retains a sheet shape in a wet state with a liquid and can be extremely easily and quickly disintegrated into a fibrous state when immersed in a large amount of water, and a method for producing the same.

[0010]

The first aspect of the present invention is a water-disintegratable non-woven fabric composed of regenerated cellulose fibers having a fiber length of 4 to 20 mm and pulp fibers, the non-woven fabric being treated with a high-pressure water jet stream. Is entangled, and JIS P
Wet strength measured by 8135 is 100-800 gf
The water-disintegratable non-woven fabric is characterized by having a thickness of / 25 mm. A second aspect of the present invention is to mix 40 to 85% by weight of regenerated cellulose fibers having a fiber length of 4 to 20 mm with 15 to 60% by weight of pulp fibers having a Canadian standard freeness of 100 to 550 ml CSF according to JIS P 8121. After forming a web with a wet paper machine using the obtained mixture, the web is placed on a transfer conveyor made of mesh, and then a high-pressure water jet stream is passed through the web on one side or both sides of the web. Is sprayed in such a manner that the fibers are entangled with each other and dried, which is a method for producing a water-disintegratable nonwoven fabric.
A third aspect of the present invention is defined in that the high-pressure water jet stream is subjected to a high-pressure water jet stream on the front surface or the back surface of the web with an additional specific energy E calculated by the formula (1) shown below. 0.1 ~ 0.6kWh / k per one side
The method for producing a water-disintegratable nonwoven fabric according to the second aspect of the present invention is characterized in that it is applied to the web in the range of g. E = {A × (2 / ρ) ^1/2 × (g × P) ^3/2 } / {M × 60 × S} (1) However, E = addition specific energy (kWh / kg) A = Sum of nozzle hole area per 1 m of web width for treating high-pressure water jet flow ρ = Water density (kg / cm ³ ) g = Gravitational acceleration (m / s ² ) P = Water pressure at nozzle (Pa) S = Web passing speed (m / min) M = Web basis weight (g / m ² ).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In order to obtain the water-disintegratable nonwoven fabric of the present invention, first, a web in which pulp fibers are mixed with regenerated cellulose fibers is prepared. Any pulp fiber may be used as long as it has a Canadian standard freeness in the range of 100 to 550 ml CSF. For example, unbleached chemical pulp obtained by cooking wood such as softwood and hardwood by the kraft method, soda method, polysulfide method, etc., and further, Hunter whiteness 70-90.
% Bleached chemical pulp is preferably used alone or in combination.

These pulp fibers have a freeness of 100-.
It may be in the range of 550 ml CSF, but 100 ml C
Pulp fibers with a SF less than SF have a considerably high degree of fibrillation, and when made into a sheet form, a dense and strong web is formed, and regenerated cellulose fibers are difficult to move due to a high-pressure water jet flow, and thus difficult to entangle. . In other words, a web that has been wet-papered and dried using such raw materials is formed of dense pulp fibers, so even if a high-pressure water jet stream is jetted onto the web, it will become pulp fibers with high freeness. In comparison, the regenerated cellulose fibers are difficult to move and are less likely to be entangled with each other. On the contrary, when the freeness exceeds 550 ml CSF, the web obtained by wet papermaking has low strength, and since the formation is poor, the strength of the nonwoven fabric obtained by the high-pressure water jet treatment is also low. , The texture will be bad.

The regenerated cellulose fibers used in the present invention are viscose rayon, which is prepared by spinning cellulose in a solution in the form of viscose and then regenerating and spinning the cellulose in an acid.
Obtained by dissolving cellulose in a copper ammonia solution, dissolving the cellulose in a non-aqueous cellulose solvent such as copper ammonia rayon, N-methylmorpholine-N-oxide regenerated and spun in an acid, and spinning. The regenerated cellulose etc. which can be mentioned are mentioned. Further, it is preferable that these fibers have low rigidity. That is, since fibers having high rigidity make it difficult for the fibers to be entangled with each other due to the high-pressure water jet flow, it becomes difficult to produce a web having a good texture, and the flexibility of the nonwoven fabric becomes poor. The shape of these fibers is not particularly limited, such as staple-like and pulp-like fibers. The cross-sectional shape of the fiber is not limited to a circular shape, and may be a fiber which is generally referred to as an atypical cross-section such as a hollow circular shape or a fiber having a splitting property, and is not particularly limited.

The length of the regenerated cellulose fiber used in the present invention is in the range of 4 to 20 mm. Fiber length is 4m
If it is less than m, the entanglement of the regenerated cellulose fibers by the water entanglement method is too weak to obtain sufficient wet strength. On the contrary, when the fiber length exceeds 20 mm, the entanglement of regenerated cellulose becomes too strong, and it becomes difficult to collapse the web structure of the nonwoven fabric in a large amount of water flow. Further, the fineness is in the range of 0.5 to 10 denier in order to emphasize flexibility. When the fineness exceeds 10 denier, the fibers themselves become hard, and when the high-pressure water jet stream is jetted and treated, it becomes difficult for the fibers to move due to the water jet stream, so high energy is required, and the entanglement of regenerated cellulose occurs. It becomes difficult and the flexibility of the nonwoven fabric is impaired. Fibers having a fineness of less than 0.5 denier are not suitable because they are difficult to manufacture.

In the present invention, regenerated cellulose fibers 40 to 8 are used.
A mixture of 5% by weight and 15-60% by weight of pulp fibers having a freeness in the range of 100 to 550 ml CSF is used as a raw material, and is a wet cylinder machine, short-span paper machine, inclined wire paper machine, fourdrinier paper machine. The paper is made into a web with, etc., and the web is sent to a high-pressure water jet stream treatment device after being dried and wound or without being dried or wound up after drying, and then a high-pressure water jet stream is applied to the surface of the web. Alternatively, the fibers are entangled by spraying them on both sides and treating them. By injecting this jet of high-pressure water, the regenerated cellulose fibers are entangled. The sheet obtained by performing this entanglement treatment firmly maintains the sheet shape when moistened with a small amount of water, but since such fiber entanglement is physically constituted, a large amount of water is used. When soaked for a long time, the entanglement of fibers loosens, and even a slight force causes breakage, so the so-called water disintegration property is extremely excellent. On the other hand, the physical bond that occurs between pulp fibers is weak sheet strength when wet,
In addition to the increased strength during drying, it does not loosen even after soaking in a large amount of water for a long time, and water disintegration hardly occurs. In addition, blending and using pulp fibers plays a role of preventing loosening of entanglement of the regenerated cellulose fibers during drying, and also plays a role of an adhesive.

If the pulp fiber content is less than 15% by weight, the strength of the web is too weak to obtain a web that can withstand the jetting process of a high-pressure water jet stream. Moreover, it is too small to play a role of preventing loosening of the entanglement of the regenerated cellulose fibers. On the other hand, if the proportion of pulp fibers exceeds 60% by weight, the pulp fibers will be too much and the amount of regenerated cellulose fibers or synthetic fibers will be small during the treatment with the high-pressure water jet stream, resulting in the entanglement of these fibers. As the web strength decreases, the web strength becomes weaker, and the bonds due to hydrogen bonds between pulp fibers increase, so that the web is not easily broken when it comes in contact with a large amount of water, resulting in poor water disintegration property. .

The basis weight of the web is in the range of 15 to 200 g / m ² . When the basis weight is less than 15 g / m ² , the strength of the web is weakened, and the sheet cannot withstand a high-pressure water jet stream, and a sheet-shaped nonwoven fabric cannot be obtained. On the other hand, when the basis weight exceeds 200 g / m ² , not only the high-pressure water jet flow needs to be applied with a high additional specific energy, but also the obtained nonwoven fabric becomes hard, making it unsuitable for use as sanitary goods and wet tissues. Becomes After the web is formed by the wet method, the high-pressure water jet stream treatment may be performed on-line as it is.
After the web is formed, it may be dried and then once taken out and subjected to a high-pressure water jet flow treatment off-line. With the latter method, a plurality of webs having different fiber blends can be stacked, and various types of sheet-shaped nonwoven fabrics can be easily formed within a range that does not impair water disintegration.

In the present invention, after the web is formed by the wet method, the web is placed on a net-made conveyor belt which is moved endlessly by a known high-pressure water jet treatment apparatus, and the web surface is removed. A high-pressure water jet stream is jetted so as to pass to the back surface, and treatment is performed. On the contrary, when the high-pressure water jet stream is applied to the back surface of the web, the web is inverted so that the back surface faces upward, and the water jet stream is jetted so that the high-pressure water jet stream passes from the back surface to the front surface. When this jet of high-pressure water is applied to the web surface on a transfer conveyor made of fabric such as wire mesh, the jet of high-pressure water first impinges on the web and then the intersection of the yarns of the fabric forming the conveyor. That is, in the knuckle portion where the weft thread and the warp thread intersect, the water jet stream cannot pass and moves in the horizontal direction. At this time, due to the water flow, the pulp fibers and the regenerated cellulose fibers undergo deformation such as bending and twisting,
In this way, sufficient kinetic energy is imparted to the fibers, causing random movement. As a result, the pulp fibers and the regenerated cellulose fibers are entangled with each other to cause fiber entanglement.

Thus, when the high-pressure water jet stream is applied to the web, the additional specific energy calculated by the equation (1) shown below is 0.1 to 0.6 kWh / k per one side.
It is applied to the web in the range of g. In the present invention, once per side means that a high-pressure water jet stream is applied to the front surface or the back surface of the web. E = {A × (2 / ρ) ^1/2 × (g × P) ^3/2 } / {M × 60 × S} (1) However, E = addition specific energy (kWh / kg) A = Sum of nozzle hole area per 1 m of web width for treating high-pressure water jet flow ρ = Water density (kg / cm ³ ) g = Gravitational acceleration (m / s ² ) P = Water pressure at nozzle (Pa) S = Web passing speed (m / min) M = Web basis weight (g / m ² ).

0.1-0.6 kWh / kg per one side
The conditions for imparting additional specific energy in the range of
It varies depending on the basis weight of the web, the nozzle hole diameter, the number of nozzle holes, the speed of passage when processing the web, and the like. When the added specific energy is larger than 0.6 kWh / kg per one side, the energy applied to the web is so strong that the entanglement becomes too strong and the wet strength is strong, but the water disintegrating property is poor. On the contrary, the additional specific energy per one side is 0.1k
If it is less than Wh / kg, the energy applied to the web is weak, and the entanglement between regenerated cellulose fibers becomes weak, so that a nonwoven fabric excellent in water disintegration can be obtained, but the wet strength becomes weak and the wet durability becomes poor. Like In the present invention, at least 0.1 kWh / kg is required when jetting a water jet flow on one side of the web as described above, and the total of the added specific energies of the water jet flows applied to both sides of the web is Even if it exceeds 0.1 kWh / kg, no effect is obtained in improving the wet strength.

The wet strength of the non-woven fabric thus obtained is in the range of 100 to 800 gf / 25 mm. When the wet strength is less than 100 gf / 25 mm, the non-woven fabric cannot be used and breaks. For example, in the case of wet tissue, it takes force to pull it out of the container,
At that time, it breaks and becomes unusable. Moreover, when the obtained non-woven fabric is used for a top sheet of a diaper, it breaks during use and cannot be used. On the other hand, if the wet strength is greater than 800 gf / 25 mm, the fibers are strongly entangled with each other and the water disintegration property is poor, which is not suitable.

In the present invention, when the web is treated with a high-pressure water jet stream, either one side or both sides may be used. That is, the term "double-sided treatment" as used herein means that the high-pressure water jet flow is first applied to the front surface of the web, and then the web is inverted so that the back surface of the web is on the upper side and the high-pressure water jet is applied from above. It means giving a flow. When the both surfaces are treated with a high-pressure water jet, the same additional specific energy may be applied to both surfaces in the range of 0.1 to 0.6 kWh / kg, or different additional specific energies may be applied to both surfaces within the above range. May be given. Drying of the nonwoven fabric in which the fiber entanglement is performed by the treatment with the high-pressure water jet stream by the method described above is dried by a dryer such as an air through dryer. When two or more webs are laminated and used, a high-pressure water jet stream may be applied to the laminate, but one web of each web may be subjected to a high-pressure water jet treatment separately and then laminated. Is also good. In particular, the latter has good water disintegration property, and even a sheet having relatively weak wet strength has sufficient strength when used,
It will be even better.

In order to use the nonwoven fabric of the present invention as a wet tissue or wiper, if desired, wetting agents such as water and propylene glycol, antibacterial agents such as alcohols and parabenzoic acid esters, and fragrances can be used. A drug may be contained. Further, when the nonwoven fabric of the present invention is used as a top sheet of a sanitary material, it can be used as it is, but it may be further treated to enhance hydrophilicity or weak water repellency. As described above, the nonwoven fabric of the present invention, wet strength, water disintegration, can be excellent in formation, wet tissue, wipers for cleaning, disposable diapers, suitable for use in sanitary napkins, etc., The used one can be washed by flushing with a flush toilet.

[0024]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In Examples and Comparative Examples,% means% by weight unless otherwise specified.

Example 1 Rayon fiber 70 having a fiber length of 7 mm and a fineness of 1.5 denier
% And 30% of bleached softwood kraft pulp fibers with a freeness of 200 ml CSF to make a 25 cm × 25 cm basis weight web of 50 g / m ² at a 0.2% concentration in a laboratory handmade machine. It was prepared and dried to a water content of 4%. This web is placed on a transfer conveyor made of a 25 mesh plain woven wire net, and while the web is being transferred at a speed of 15 m / min, a nozzle hole having a hole diameter of 0.1 mm is 0.64 mm.
Using three rows of high-pressure water jet jets arranged in a zigzag pattern at intervals, a high-pressure water jet jet was jetted at a water pressure of 35 kg / cm ² so that the water jet jet penetrated from the front surface to the back surface of the web. . Addition energy is 0.3kWh
/ Kg. Then, it was dried with a hot air dryer at a temperature of 150 ° C. to obtain a water-disintegratable nonwoven fabric. The resulting nonwoven fabric was evaluated for quality by measuring the wet strength, water disintegration property and formation by the following test methods.

Test method (1) Wet strength: Wet strength of the water-disintegratable nonwoven fabric is 25 mm in width and 100 in length.
After cutting into mm, it was immersed in physiological saline for 1 minute, taken out, lightly wiped off with water with filter paper, and attached to a universal compression tensile tester (Strograph V1-B, manufactured by Toyo Seiki Co., Ltd.),
Tensile speed 200 mm / min, gripping interval of test piece 80 mm
The test was carried out under the conditions of, and the load instruction value at break was taken as the wet strength. In the present invention, the nonwoven fabric has a wet strength of 100 to 800.
If it is not within the range of gf / 25 mm, the balance between strength when wet and water disintegration cannot be well balanced. (2) Water disintegration Put 500 ml of water into a 1 liter beaker and stir at 50 rpm with a stirrer at 50 × 50 m.
The cut non-woven fabric piece was put into m and the disintegration state 90 seconds later was visually evaluated. The judgment at this time was made into the following four levels. A: The sheet completely collapses and becomes fibrous. ◯: The sheet is disintegrated, but both fibrous substances and fiber lumps are mixed. Δ: The sheet shape is collapsed and the fibers are lumps. X: The sheet shape is maintained. (3) Formation The obtained non-woven fabric was placed on black drawing paper, and the formation was visually evaluated. The judgment at this time was made into the following four levels. ◎: good. ○: Somewhat good. Δ: Somewhat poor. X: Poor.

Example ² A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that rayon fiber having a fiber length of 5 mm was used.
After drying, a jet of high-pressure water was jetted onto the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 3 The basis weight was 30 g / m ^{2 in the same} manner as in Example 1 except that rayon fiber having a fiber length of 18 mm and a fineness of 3 denier was used.
After the web was prepared and dried, a high-pressure water jet stream was jetted onto the surface of the web at a water pressure of 20 kg / cm ² while transporting the web at a speed of 15 m / min and dried to obtain a nonwoven fabric. . Added specific energy is 0.21 kWh / k
g. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 4 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that a mixture consisting of 80% rayon fiber and 20% softwood kraft pulp was used, dried, and then dried under high pressure water. A jet stream was jetted onto the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The resulting non-woven fabric was tested as in Example 1,
The quality was evaluated.

Example 5 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that a mixture of 50% rayon fiber and 50% softwood kraft pulp was used. A jet stream was jetted onto the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The resulting non-woven fabric was tested as in Example 1,
The quality was evaluated.

Example 6 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that softwood kraft pulp having a freeness of 500 ml CSF was used, and after drying, a high-pressure water jet stream was applied to the surface of the web. And then dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 7 When jetting a high-pressure water jet stream to a web having a basis weight of 50 g / m ² , the web is transported at a speed of 15 m / min, and a high-pressure water jet is produced at a water pressure of 25 kg / cm ^2. A nonwoven fabric was obtained in the same manner as in Example 1 except that the flow was applied only to the surface of the web. The additional specific energy at this time is
It was 0.18 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 8 When a web having a basis weight of 50 g / m ² was treated by jetting a high-pressure water jet, the web was transferred to the surface of the web at a speed of 15 m / min while the pressure was 20 kg / cm ² . 20 kg / c while treating the high-pressure water jet stream with water pressure and transferring the web to the back side of the web at a speed of 15 m / min.
except that the high pressure water jet stream was treated with a water pressure of m ² .
A nonwoven fabric was obtained in the same manner as in Example 1. The additional specific energy at this time was 0.26 kWh / kg in total on both sides. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 9 When jetting a high-pressure water jet stream to a web having a basis weight of 50 g / m ² , the web was transported at a speed of 15 m / min while the high-pressure water jet was run at a water pressure of 50 kg / cm ^2. A nonwoven fabric was obtained in the same manner as in Example 1 except that the flow was applied only to the surface of the web. The additional specific energy at this time is
It was 0.51 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 10 Except that a web having a basis weight of 25 g / m ² was prepared, high-pressure water was applied at a water pressure of 30 kg / cm ² while transferring the web at a speed of 15 m / min in the same manner as in Example 1. The jet stream was sprayed only on the surface of the web and then dried to obtain a nonwoven fabric. The added specific energy was 0.47 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Example 11 A grammage of 80 g / gram was obtained in the same manner as in Example 1 except that bleached softwood kraft pulp having a freeness of 500 ml CFS was used.
A m ² web was made and dried. Then, while transferring this web at a speed of 15 m / min, 75 kg / c
A high-pressure water jet was sprayed only on the surface of the web at a water pressure of m ² and then dried to obtain a nonwoven fabric. The added specific energy is
It was 0.53 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 1 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that a mixture of 95% rayon fiber and 5% softwood kraft pulp was used, dried, and then dried under high pressure water. A jet stream was jetted onto the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 2 A web having a basis weight of 50 g / m ² was prepared and dried in the same manner as in Example 1 except that a mixture of 30% rayon fiber and 70% bleached softwood kraft pulp was used. A high-pressure water jet stream was sprayed onto the surface of the web and dried to obtain a nonwoven fabric. Added specific energy is 0.3kWh / kg
Met. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 3 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that rayon fibers having a fiber length of 3 mm were used.
After drying, a jet of high-pressure water was jetted onto the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 4 The basis weight was 30 g / m ^{2 in the same} manner as in Example 1 except that rayon fiber having a fiber length of 25 mm and a fineness of 3 denier was used.
After the web was prepared and dried, a high-pressure water jet stream was jetted onto the surface of the web at a water pressure of 20 kg / cm ² while transporting the web at a speed of 15 m / min and dried to obtain a nonwoven fabric. . Added specific energy is 0.21 kWh / k
g. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 5 A web having a basis weight of 50 g / m ² was prepared in the same manner as in Example 1 except that softwood bleached kraft pulp having a freeness of 50 ml CSF was used. After drying, a high-pressure water jet stream was applied to the web. It was sprayed from the surface and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 6 Basis weight of 50 g / m ^{2 in the same} manner as in Example 1 except that softwood bleached kraft pulp having a freeness of 630 ml CSF was used.
The web was prepared and dried, and then a high-pressure water jet stream was jetted from the surface of the web and dried to obtain a nonwoven fabric. The added specific energy was 0.3 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 7 When a web having a basis weight of 50 g / m ² was treated by jetting a high-pressure water jet, the web was transported to the surface at a speed of 15 m / min, and a pressure of 14 kg / cm ² was applied. High pressure water jet stream is processed by water pressure, and further 14kg / c while transferring the web to the back side of the web at a speed of 15m / min.
except that the high pressure water jet stream was treated with a water pressure of m ² .
A nonwoven fabric was obtained in the same manner as in Example 1. The additional specific energy at this time was 0.08 kWh / kg per one side, and the total of both sides was 0.16 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Comparative Example 8 When a high-pressure water jet stream was jetted onto a web having a basis weight of 50 g / m ² , the web was transported at a speed of 15 m / min while the high-pressure water jet was operated at a water pressure of 110 kg / cm ^2. A nonwoven fabric was obtained in the same manner as in Example 1 except that the flow was applied only to the surface of the web. The additional specific energy at this time is
It was 1.66 kWh / kg. The obtained nonwoven fabric was tested in the same manner as in Example 1 and its quality was evaluated.

Table 1 shows the results obtained in Examples 1 to 11 and Comparative Examples 1 to 8.

[0046]

[Table 1]

As can be seen from Table 1, the non-woven fabric obtained according to the present invention has high wet strength and is excellent in water disintegration and formation. On the other hand, when the proportion of pulp fibers used is small (Comparative Example 1), the texture of the web is poor at the time of manufacturing the web, and the nonwoven fabric does not have the strength to withstand the high-pressure water jet flow. However, it is inferior in formation and wet strength. When the proportion of pulp fiber used is high (Comparative Example 2)
When the high-pressure water jet flow treatment is applied, the water jet causes the pulp fibers to be washed away.
Excellent wet strength and water disintegration, but poor formation. When the fiber length of the regenerated cellulose fiber is too short (Comparative Example 3), the nonwoven fabric is excellent in water disintegratability, but the wet strength and texture are deteriorated, and when the fiber length of the regenerated cellulose fiber is too long (Comparative Example 4). , Excellent in wet strength and texture but poor in water disintegration.

If the freeness of the pulp is too low (Comparative Example 5), the web is tightly held by the pulp fibers even if the formation is excellent, so that the regenerated cellulose fibers are commingled with each other by the high pressure water jet flow. Are less likely to be entangled with each other and have excellent water disintegration property, but poor wet strength. On the contrary, when the freeness of the pulp is too high (Comparative Example 6), the formation of the web is deteriorated during the production of the web, so that the nonwoven fabric obtained by applying the high-pressure water jet flow is water-disintegratable. It has excellent wet strength and poor texture. On the other hand, if the additional specific energy per one side is too low (Comparative Example 7), the entanglement of the regenerated cellulose fibers becomes insufficient and the water disintegration is excellent, but the wet strength and texture are poor. On the other hand, when the added specific energy is too high (Comparative Example 8), the entanglement of the regenerated cellulose fibers becomes strong due to the high-pressure water jet flow, and the formation and wet strength are excellent, but the water disintegratability is poor.

[0049]

As described above, according to the present invention, a web composed of a mixture of regenerated cellulose fibers and pulp fibers is sufficiently entangled with the regenerated cellulose fibers by a high-pressure water jet stream, whereby an adhesive is used. The effect of providing a water-disintegratable non-woven fabric and a method for producing the non-woven fabric, which has a strong strength in a wet state with a liquid at the time of use, is excellent in formation, and whose web constitution is easily collapsed by a large amount of water. Play.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichiro Ogawa 1-10-6 Shinonome, Koto-ku, Tokyo Shin-Oji Paper Co., Ltd. Shinonome Research Center (72) Inventor Daishiro Matsuda 1-10 Shinonome, Koto-ku, Tokyo No. 6 Shin Oji Paper Co., Ltd. Shinonome Research Center

Claims (3)

[Claims] 1. A water-disintegratable non-woven fabric comprising regenerated cellulose fibers having a fiber length of 4 to 20 mm and pulp fibers, wherein the non-woven fabric is entangled with each other by a high-pressure water jet treatment and measured according to JIS P 8135. A water-disintegratable nonwoven fabric having a wet strength of 100 to 800 gf / 25 mm. 2. A mixture of 40 to 85% by weight of regenerated cellulose fibers having a fiber length of 4 to 20 mm and 15 to 60% by weight of pulp fibers having a Canadian standard freeness of 100 to 550 ml CSF according to JIS P 8121 is obtained. After forming a web on a wet paper machine with the mixture to be applied, the web is placed on a net transfer conveyor and then a jet of high pressure water is passed through the web on one or both sides of the web. A method for producing a water-disintegratable non-woven fabric, which comprises spraying onto a fiber to entangle fibers and drying. 3. The one-sided surface defined by applying a high-pressure water jet stream to the front surface or the back surface of the web with the additional specific energy E calculated by the formula (1) shown below. 0.1 to 0.6 kWh / kg per time
It is provided to the web in the range of
A method for producing the water-disintegratable nonwoven fabric described. E = {A × (2 / ρ) ^1/2 × (g × P) ^3/2 } / {M × 60 × S} (1) However, E = addition specific energy (kWh / kg) A = Sum of nozzle hole area per 1 m of web width for treating high-pressure water jet flow ρ = Water density (kg / cm ³ ) g = Gravitational acceleration (m / s ² ) P = Water pressure at nozzle (Pa) S = Web passing speed (m / min) M = Web basis weight (g / m ² ).