WO2016140356A1

WO2016140356A1 - Rayon yarn for wet-laid nonwoven fabric and method for producing same, wet-laid nonwoven fabric and method for producing same, and hydrolyzable paper

Info

Publication number: WO2016140356A1
Application number: PCT/JP2016/056877
Authority: WO
Inventors: 川見愛奈; 林誠
Original assignee: ダイワボウホールディングス株式会社; ダイワボウレーヨン株式会社
Priority date: 2015-03-04
Filing date: 2016-03-04
Publication date: 2016-09-09
Also published as: JPWO2016140356A1; JP6678642B2

Abstract

The present invention pertains to a rayon yarn for use in a wet-laid nonwoven fabric and having an average crimp rate of 16-45%, inclusive. This rayon yarn for use in a wet-laid nonwoven fabric is produced by using a method for producing a rayon yarn by discharging viscose from a spinning nozzle into a spinning bath, forming a line of yarn by solidifying and regenerating the viscose, and withdrawing, extending, and scouring the line of yarn, wherein the extension is separated into two stages of extension, the rate of extension in the first extension stage is 30% or less, and the rate of extension in the second extension stage is 3.0% or less. The present invention further pertains to a wet-laid nonwoven fabric containing the abovementioned rayon yarn for use in a wet-laid nonwoven fabric, and a hydrolyzable paper containing the abovementioned wet-laid nonwoven fabric. The present invention provides: a rayon yarn for use in a wet-laid nonwoven fabric and exhibiting prescribed crimping, favorable water dispersion properties when dry, and interlacing properties when forming a nonwoven fabric; a method for producing the same; a wet-laid nonwoven fabric; a method for producing the same; and a hydrolyzable paper.

Description

Rayon fiber for wet nonwoven fabric and method for producing the same, wet nonwoven fabric and method for producing the same, and hydrolytic paper

The present invention relates to a rayon fiber for wet nonwoven fabric and a method for producing the same, a wet nonwoven fabric and a method for producing the same, and hydrolytic paper.

In recent years, non-woven fabrics have been increasingly used in place of cloth for care products, sanitary products, diapers, cleaning articles, cleaning sheets, and the like. For these nonwoven fabrics, rayon fibers have been used. For example, Patent Literature 1 describes a water-decomposable nonwoven fabric composed of rayon fibers and pulp fibers having a fiber length of 7 mm or less that can be used as a cleaning article. Patent Document 2 discloses that a substrate having no ionicity such as viscose rayon, a resin having an anionic group, and a cationic property, which are used when forming a wet-responsive nonwoven fabric used for hygiene products. Wet responsive fibers having monofilaments formed from a resin composition comprising a resin are described.

Japanese Patent Laid-Open No. 11-279915 JP 2000-248422 A

However, in consideration of water dispersibility, conventional rayon fibers for wet non-woven fabrics are mainly made of so-called straight fibers that are in a wet state containing moisture and have no crimps. For this reason, it has been found that there is a problem that, when forming a wet nonwoven fabric, the entanglement between the fibers of the rayon fiber alone is poor, or the entanglement is not good when the obtained wet papermaking is subjected to hydroentanglement treatment.

In order to solve the above problems, the present invention has a predetermined crimp and has good water dispersibility even in a dry state, and has a entanglement property at the time of forming a nonwoven fabric and a method for producing the same. A wet nonwoven fabric, a method for producing the same, and hydrolytic paper are provided.

The present invention relates to a rayon fiber for wet nonwoven fabric, wherein the average crimp rate is 16% or more and 45% or less.

The rayon fiber for wet nonwoven fabric preferably contains more than 5% of fibers having a crimp space portion height of 0.70 mm or more. Moreover, it is preferable that the value of ratio L / D of fiber length L and fiber width D is 350-1200 in the said rayon fiber for wet nonwoven fabrics. Moreover, it is preferable that the said average number of crimps of the rayon fiber for wet nonwoven fabrics is 3 piece / inch or more and 25 piece / inch or less. Moreover, it is preferable that the said rayon fiber for wet nonwoven fabrics contains 0.03 mass% or more and 0.2 mass% or less of an oil agent with respect to the whole mass of a fiber. The oil agent is preferably a polyoxyethylene ester nonionic surfactant.

The present invention also provides a rayon fiber by discharging viscose from a spinning nozzle into a spinning bath, solidifying and regenerating the viscose to form a yarn, drawing the yarn, drawing and scouring. In this method, the above-mentioned stretching is made into two-stage stretching, the stretching ratio in the first-stage stretching is 30% or less, and the stretching ratio in the second-stage stretching is 3.0% or less, so that the average crimping ratio is The present invention relates to a method for producing a rayon fiber for wet nonwoven fabric, which is characterized by obtaining a rayon fiber of 16% to 45%.

It is preferable that the drawn yarn is cut into a predetermined fiber length before scouring.

The present invention also relates to a wet nonwoven fabric characterized by comprising the above-described rayon fiber for wet nonwoven fabric.

The wet nonwoven fabric may contain 5 to 95 mass% of the rayon fiber for wet nonwoven fabric and 5 to 95 mass% of the pulp with respect to 100 mass% of the wet nonwoven fabric. The wet nonwoven fabric is preferably a wet hydroentangled nonwoven fabric.

The present invention also includes a step of producing a wet papermaking web with a wet papermaking machine using a mixture containing the above-described wet nonwoven fabric rayon fiber and pulp, and jetting a waterflow onto at least one surface of the wet papermaking web. The present invention relates to a method for producing a wet nonwoven fabric including a step of entanglement.

The present invention also relates to a hydrolytic paper characterized by including the wet nonwoven fabric described above.

The present invention relates to a rayon fiber for wet nonwoven fabric having a predetermined crimp and having good water dispersibility even in a dry state and having entanglement properties at the time of forming the nonwoven fabric, a method for producing the same, and a wet nonwoven fabric using the same. provide. The wet nonwoven fabric of the present invention can be suitably used as hydrolytic paper.

FIG. 1A is a side view photograph (25 times) of the rayon fiber for wet nonwoven fabric of Example 1, and FIG. 1B is a side view photograph (50 times) of the rayon fiber for wet nonwoven fabric. 2A is a side view photograph (25 times) of the rayon fiber of Comparative Example 1, and FIG. 2B is a side view photograph (50 times) of the rayon fiber. 2C is a side view photograph (25 times) of the rayon fiber of Comparative Example 3, and FIG. 2D is a side view photograph (50 times) of the rayon fiber. 2E is a side view photograph (25 times) of the rayon fiber of Comparative Example 5, and FIG. 2F is a side view photograph (50 times) of the rayon fiber. FIG. 3 is an explanatory diagram of a method for measuring the crimp rate of the fiber. FIG. 4 is an explanatory diagram of a method for measuring the height of the crimped space portion of the fiber. 5A is a surface photograph (100 times) of the nonwoven fabric after papermaking in Example 2, and FIG. 5B is a cross-sectional photograph (100 times) of the nonwoven fabric after papermaking. FIG. 5C is a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Example 2, and FIG. 5D is a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement. 6A is a surface photograph (100 times) of the nonwoven fabric after papermaking in Comparative Example 6, and FIG. 6B is a cross-sectional photograph (100 times) of the nonwoven fabric after papermaking. 6C is a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Comparative Example 6, and FIG. 6D is a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement. FIG. 7A is a surface photograph (100 times) of the nonwoven fabric after paper making in Comparative Example 7, and FIG. 7B is a cross-sectional photograph (100 times) of the nonwoven fabric after paper making. FIG. 7C is a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Comparative Example 7, and FIG. 7D is a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement. FIG. 8 is a cross-sectional photograph (40 ×) of the wet hydroentangled nonwoven fabric of Example C9 taken with an electron microscope.

The wet crimped rayon fiber (wet laid rayon fiber) has an average crimp rate of 16% to 45%. When the average crimping rate is 45% or less, the water dispersibility during slurry formation before wet papermaking is excellent. Further, when the average crimp rate is 16% or more, the water dispersibility is excellent and the fibers are easily entangled with each other when producing the nonwoven fabric. The average crimp rate is preferably 18% or more, and more preferably 20% or more. Moreover, from the viewpoint of improving water dispersibility, the above-mentioned rayon fiber for wet nonwoven fabric preferably has an average crimp rate of 40% or less, more preferably 35% or less, and further preferably 30% or less. .

In the present invention, the “crimp rate” is calculated by the following formula when the length of a straight line connecting both end points of the fiber is a (mm) and the fiber length is L (mm). “Average crimp ratio” refers to an average value of crimp ratios of 20 fibers arbitrarily selected.
Crimp rate (%) = (La) / L × 100

In the rayon fiber for wet nonwoven fabric, the crimp is a natural crimp and preferably has a three-dimensional shape. Natural crimp is different from mechanical crimp imparted by a machine such as a stuffer box crimper, and is a crimp that naturally develops during the manufacturing stage such as fiber spinning or scouring stage. The rayon fiber for wet nonwoven fabric preferably has a predetermined weak natural crimp from the viewpoint that the fibers are easily entangled with each other when the nonwoven fabric is produced.

The above-mentioned rayon fibers for wet nonwoven fabrics preferably have an average number of crimps of 3 / inch to 25 / inch from the viewpoint of improvement in water dispersibility and entanglement at the time of nonwoven fabric formation. More preferably, the average number of crimps is 5 pieces / inch or more and 20 pieces / inch or less, and further preferably 8 pieces / inch or more and 15 pieces / inch or less.

In the present invention, the “crimp number” is based on the total number X (number) of crimp peaks and valleys in a predetermined fiber and the fiber length Y (mm) after the fiber is stretched until there is no crimp. The “average crimp rate” is an average value of the number of crimps of 20 fibers selected arbitrarily.
Number of crimps (pieces / inch) = (X / 2) × (25.4 / Y)

The rayon fiber for wet nonwoven fabric preferably contains more than 5% of fibers having a height of crimp space of 0.70 mm or more from the viewpoint of improvement in water dispersibility and entanglement at the time of nonwoven fabric formation. More preferably, it is 10% or more, More preferably, it is 15% or more.

In the present invention, “the height of the crimped space portion” refers to the length of a perpendicular drawn from the apex of the crimped portion toward the straight line drawn from the crimped portion to the bottom of the crimped portion. In addition, when one fiber has a plurality of crimp portions, the height of the largest crimp space portion is set as the height of the crimp space portion of the fiber.

From the viewpoint of improving water decomposability, the wet nonwoven fabric rayon fiber preferably has a ratio L / D of the fiber length L to the fiber width D of 350 or more and 1200 or less, and more preferably 500 or more and 1000 or less. More preferably, it is 550 or more and 850 or less.

In the present invention, the fiber width D is obtained by converting the fiber cross section into a perfect circle and calculating the value from the cross sectional area.

It is preferable that 0.03% by mass or more and 0.20% by mass or less of the oil agent is attached to the above-described wet nonwoven fabric rayon fiber with respect to the total mass of the fiber. It is more preferable that it adheres, and it is further more preferable that it adheres 0.04 mass% or more and 0.15 mass% or less. Water adhesion can be improved, without impairing the hydrophilic property of rayon fiber as the adhesion rate of an oil agent exists in said range.

Although the rayon fiber for wet nonwoven fabric is not particularly limited, the fiber length is preferably 4 to 20 mm, more preferably 6 to 16 mm, and still more preferably 8 to 12 mm from the viewpoint of water dispersibility.

The wet nonwoven fabric rayon fiber is not particularly limited, but from the viewpoint of water dispersibility, the fineness is preferably 0.4 to 3.5 dtex, more preferably 1.0 to 3.0 dtex, and still more preferably. Is 1.6 to 2.5 dtex.

The rayon fiber for wet nonwoven fabric is formed by discharging viscose from a spinning nozzle into a spinning bath, solidifying and regenerating the viscose to form a yarn, drawing the yarn, stretching, and scouring. It can be obtained by stretching under specific stretching conditions.

The viscose may be of a general composition and is not particularly limited. For example, it is preferable to use viscose containing 7 to 10% by mass of cellulose, 5 to 8% by mass of sodium hydroxide, and 2 to 4% by mass of carbon disulfide with respect to 100% by mass of viscose.

Furthermore, the above-mentioned viscose is kneaded with additives such as various organic substances (oils and fats, compounds having functional groups, functional materials such as proteins) and inorganic substances (pigments and minerals such as titanium oxide) to impart functionality. can do.

The spinning bath (Mueller bath) may be a general acidic spinning bath and is not particularly limited. For example, an aqueous solution containing 95 to 130 g / L of sulfuric acid, 10 to 17 g / L of zinc sulfate, and 290 to 370 g / L of mirabilite can be used. In the spinning bath, the sulfuric acid concentration is preferably 100 to 120 g / L. When the sulfuric acid concentration of the spinning bath is within the above range, the spinning processability is improved.

The spinning nozzle is not particularly limited, and a round nozzle, a flat nozzle, a modified nozzle such as a Y-type nozzle, or the like can be used. When a circular nozzle is used, fineness adjustment is easy. The selection of the spinning nozzle depends on the target production volume, but preferably has a circular nozzle having a diameter of 0.03 to 0.10 mm and 1000 to 20000 holes.

The yarn formed by extruding and spinning the viscose into a spinning bath and solidifying and regenerating is drawn. The stretching is a two-stage stretching, the first stretching ratio in the first stage stretching is 30% or less, and the second stretching ratio in the second stage stretching is 3.0% or less. By setting the first draw ratio and the second draw ratio within the above ranges, rayon fibers having an average crimp ratio of 16% to 45% can be obtained. The first stretching ratio is preferably 3 to 25%, more preferably 5 to 20%. The second stretching ratio is preferably 0.3 to 2.5%, more preferably 0.5 to 2.0%. The stretching is preferably performed with a godet roller. In the present invention, the “stretch rate” indicates how many percent the length of the yarn after stretching is to be extended when the length of the yarn before stretching is 100%.

The spinning speed after stretching is, for example, preferably in the range of 25 to 70 m / min, and more preferably in the range of 30 to 65 m / min.

After the drawn yarn obtained above is cut to a predetermined length, it is subjected to heat treatment, ie, scouring treatment, in a heated liquid. By cutting the yarn that has been stretched at a predetermined magnification, stress relaxation occurs, the fiber contracts, and a fiber having a predetermined crimp can be obtained. Subsequently, the contracted fiber is regenerated by removing carbon disulfide contained in the fiber in the heated liquid and fixing the crimped state, whereby a fiber having a predetermined crimp can be obtained. The scouring may be carried out in the order of heat treatment (hot water treatment), hydrosulfurization treatment, bleaching, pickling and oiling in a heated solution by a normal method. The temperature of the heated liquid (such as water) is preferably 70 to 90 ° C. More preferably, it is 75 to 85 ° C. Since the cut length shrinks in the scouring process and the drying process, it is preferably set to 3 to 10% longer than the product fiber length.

The oil agent is preferably applied using an oil agent such as a polyoxyethylene (POE) ester nonionic surfactant. The adhesion rate of the oil agent is preferably 0.03% by mass or more and 0.2% by mass or less, more preferably 0.03% by mass or more and 0.18% by mass or less, with respect to 100% by mass of the fiber. Preferably they are 0.04 mass% or more and 0.15 mass% or less.

After scouring, if necessary, excess oil agent and moisture can be removed from the fiber by a method such as a compression roller or vacuum suction, followed by drying treatment. The drying treatment is preferably performed at a temperature of 50 to 120 ° C. for 0.05 to 15 hours. More preferably, the temperature is 70 to 110 ° C. and the treatment time is 0.1 to 8 hours.

The rayon fiber for wet nonwoven fabric is excellent in water dispersibility. In the present invention, “water dispersibility” means that 90 L of water is stirred with a stirrer at a rotational speed of 2000 rpm, and fibers (raw cotton) corresponding to an absolutely dry mass of 4.5 g are added thereto, followed by stirring one minute after the addition. Can be determined by measuring the number of fiber clumps immediately after stopping stirring. From the viewpoint of excellent water dispersibility, in the evaluation of water dispersibility, the wet nonwoven fabric rayon fiber preferably has less than 20 fibers, more preferably 18 or less, and more preferably 16 or less. More preferably it is. In the present invention, for example, an absolutely dry fiber can be obtained by drying at 105 ° C. for 2 hours.

The wet nonwoven fabric of the present invention includes the rayon fiber for wet nonwoven fabric. The wet nonwoven fabric preferably contains 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass of the rayon fiber for wet nonwoven fabric with respect to 100% by mass of the nonwoven fabric.

The wet nonwoven fabric may contain other fibers in addition to the wet nonwoven fabric rayon fiber. Examples of other fibers include natural fibers such as pulp, cotton (linter), hemp, and bamboo, and synthetic fibers such as polyester, polyamide, and polyolefin. For example, when used for hydrolytic paper, it is preferable to include pulp. When hydrolyzed paper is prepared by mixing the above-mentioned wet nonwoven fabric rayon fiber with pulp, improvement in flashability (water decomposability) and practical strength is expected. In addition, other fiber materials (for example, binder fibers) and paper strength enhancers may be added as long as the performance is not impaired.

The wet nonwoven fabric is not particularly limited, but in terms of processability, the basis weight is preferably 15 to 150 g / m ² , more preferably 20 to 100 g / m ² , and 30 to 80 g / m ² . More preferably it is.

The wet nonwoven fabric is not particularly limited, and is a wet hydroentangled nonwoven fabric (also referred to as a wet spunlace nonwoven fabric), a wet heat fusion nonwoven fabric, a wet wet heat fusion nonwoven fabric, a wet obtained by combining with a beaten pulp. Any of a nonwoven fabric etc. may be sufficient. From the viewpoint of 100% cellulose environmentally friendly products, wet hydroentangled nonwoven fabrics are preferred. Papermaking and hydroentanglement can be performed by a general method.

The wet nonwoven fabric may be used as a single layer of wet nonwoven fabric, or may be used in wet papermaking or lamination of a wet nonwoven fabric with another nonwoven fabric.

When used as hydrolytic paper, the wet nonwoven fabric may contain 5% by mass to 95% by mass of rayon fiber for wet nonwoven fabric of the present invention and 5% by mass to 95% by mass of pulp with respect to 100% by mass of the wet nonwoven fabric. Good. The wet nonwoven fabric preferably contains 80% by mass or less, more preferably 60% by mass or less, and even more preferably 40% of the wet nonwoven fabric rayon fiber of the present invention with respect to 100% by mass of the wet nonwoven fabric. Including mass% or less. Moreover, it is more preferable to contain 10 mass% or more of the rayon fiber for wet nonwoven fabrics of this invention with respect to 100 mass% of wet nonwoven fabrics, It is further more preferable to contain 15 mass% or more, More preferably, it contains 20 mass% or more, Even more preferably, it contains 30% by mass or more. The wet nonwoven fabric preferably contains 90% by mass or less of pulp, more preferably 85% by mass or less, and still more preferably 80% by mass or less, relative to 100% by mass of the wet nonwoven fabric. It is even more preferable that the content is not more than mass%. Moreover, it is preferable that the said wet nonwoven fabric contains 20 mass% or more of pulp with respect to 100 mass% of wet nonwoven fabrics, It is more preferable that 40 mass% or more is included, It is further more preferable that 60 mass% or more is included. A wet nonwoven fabric having excellent water decomposability and excellent tensile strength and tensile elongation can be obtained. Conventionally, when a wet hydroentangled nonwoven fabric containing recycled cellulose fibers and pulp is used as the hydrolytic paper, the pulp content is low (for example, less than 15% by mass), the web strength is too weak, and hydroentanglement cannot be performed, or When the content of regenerated cellulose fiber is large (for example, more than 55% by mass), the pulp is sufficiently beaten to increase the binding strength, and sufficient fiber entanglement cannot be obtained unless large energy is given by hydroentanglement treatment. It was broken. On the other hand, if the pulp content is too high (for example, more than 60% by mass), the entanglement of the cellulose fibers is too small and the web strength is weakened, and the hydrogen bonds of the pulp are increased, resulting in poor hydrolyzability, or regenerated cellulose. It has been said that if the amount of fibers is small (for example, less than 15% by mass), sufficient wet strength and excellent water disintegrability cannot be imparted. On the other hand, by using the rayon fiber for wet nonwoven fabric (wet laid) of the present invention as the regenerated cellulose fiber, it is for hydrolytic paper having sufficient wet strength and water disintegration even if the mixing ratio of rayon fiber is small compared with pulp. A wet nonwoven fabric is obtained. Moreover, even if the mixing ratio of rayon fibers is larger than that of pulp, a wet nonwoven fabric for hydrolytic paper having moderate strength and hydrolytic properties as hydrolytic paper can be obtained.

When used as water disintegrating paper, the wet nonwoven fabric preferably has a basis weight of 30 to 90 g / m ² and more preferably 30 to 80 g / m ² from the viewpoint of excellent water disintegrating property. Further, from the viewpoint of excellent water decomposability, the wet nonwoven fabric preferably has a thickness of 0.2 to 2.0 mm, and more preferably 0.3 to 1.5 mm. From the viewpoint of excellent water disintegrability, the wet nonwoven fabric preferably has a specific volume of 3.0 to 25.0 cm ³ / g, more preferably 5.0 to 20.0 cm ³ / g. The basis weight, thickness and specific volume are measured and calculated as described later.

The wet nonwoven fabric preferably has a wet tensile strength of 0.2 to 8.0 N / 25 mm in the longitudinal direction, preferably 0.3 to 8.0 N / 25 mm in the transverse direction, and has a geometric mean wetness. The tensile strength is preferably 0.3 to 10.0 N / 25 mm. The wet tensile elongation is preferably 7 to 45% / 25 mm in the longitudinal direction, and preferably 10 to 45% / 25 mm in the transverse direction, and the geometric average wet tensile elongation is 14 to 61%. / 25 mm is preferable. When the wet tensile strength and wet tensile elongation are within the above-described ranges, the handleability is good while having good water disintegration.

The wet nonwoven fabric preferably has a dry tensile strength of 4.0 to 21.0 N / 25 mm in the longitudinal direction, preferably 4.0 to 23.0 N / 25 mm in the transverse direction, and has a geometric average dryness. The tensile strength is preferably 5 to 30 N / 25 mm. Further, the dry tensile elongation is preferably 5 to 40% / 25 mm in the longitudinal direction, and preferably 15 to 40% / 25 mm in the transverse direction, and the geometric average dry tensile elongation is 15 to 47%. / 25 mm is preferable. When the dry tensile strength and the dry tensile elongation are within the above-described ranges, the handleability is improved while having good water disintegrability.

In the present invention, the tensile strength and the tensile elongation are measured according to JIS P 8135. Specifically, the measurement is performed as described below. The geometric average tensile strength and tensile elongation are calculated as described below.

The wet hydroentangled non-woven fabric is a mixture of the wet non-woven fabric rayon fiber and pulp made into a wet paper web by a paper machine, and then sprayed with a high-pressure water stream at a predetermined water pressure on at least one surface of the wet paper web. It can be produced by hydroentanglement. The water pressure of the high-pressure water stream is preferably 1.5 MPa or more and 5.5 MPa or less from the viewpoint of obtaining a nonwoven fabric having good entanglement properties.

The wet nonwoven fabric can be used in either a dry state or a wet state. For example, it can be used for care products, sanitary products, diapers, cleaning articles, cleaning sheets, and the like. Since the wet nonwoven fabric contains rayon fibers for wet nonwoven fabric, the wet nonwoven fabric can be used as it is for water-disintegrating paper that flows to a flush toilet or the like.

The hydrolytic paper containing the wet nonwoven fabric of the present invention can be used in either a dry state or a wet state. The above-mentioned water disintegrating paper is a drug or liquid appropriately set according to the application (for example, a moisturizing component, a cleansing (cleaning) component, an antiperspirant component, a scent component, a whitening component, a blood circulation promoting component, an ultraviolet ray preventing component, A slimming component or the like) may be attached or impregnated in a predetermined amount and stored in a storage body to be used as a sheet product.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited to the following Example.

(Example 1)
As the viscose, one containing 8.5% by mass of cellulose, 5.7% by mass of sodium hydroxide, and 2.8% by mass of carbon disulfide was used. As the spinning bath, a Mueller bath containing 100 g / L of sulfuric acid, 15 g / L of zinc sulfate, and 350 g / L of sodium sulfate was used. As the spinning nozzle for discharging viscose, one having 4000 nozzle holes having a hole diameter of 0.06 mm was used.

After extruding the viscose into a spinning bath, two-stage stretching was performed. The first stretch ratio in the first stage stretching was 10%, and the second stretch ratio in the second stage stretching was 0.7%. The drawn yarn was drawn at a take-up speed (spinning speed) of 35 m / min with a stretcher roller. After the cut yarn was cut to 10.5 mm, heat treatment was performed in hot water at 82 ° C., followed by scouring in the order of hydrosulfurization treatment, bleaching, pickling and oiling. The oil agent application was performed using an oil agent circulating liquid containing 0.25% by mass of a POE ester nonionic surfactant. The temperature of the oil circulating liquid was 40 ° C. The adhesion amount of the oil agent was 0.08% by mass with respect to 100% by mass of the fiber. The fiber after scouring was dried at 80 ° C. for 60 minutes to obtain a rayon fiber for wet nonwoven fabric having a fineness of 2.2 dtex and a fiber length of 10 mm.

(Example 2)
Spinning, scouring, and drying were performed under the same conditions as in Example 1 except that the take-up speed at the stretcher roller was 40 m / min, and the taken-up yarn was cut into the length shown in Table 2 below. A rayon fiber for wet non-woven fabric having 1.7 dtex was obtained.

(Example 3)
Except that the taken yarn was cut to the length shown in Table 2 below, spinning, scouring and drying were performed under the same conditions as in Example 1 to obtain a wet nonwoven fabric rayon fiber having a fineness of 2.2 dtex. .

Example 4
Spinning, scouring, and drying were performed under the same conditions as in Example 1 except that the take-up speed at the stretcher roller was 40 m / min, and the taken-up yarn was cut into the length shown in Table 2 below. A rayon fiber for wet non-woven fabric of 2.2 dtex was obtained.

(Comparative Example 1)
As the viscose, one containing 8.5% by mass of cellulose, 5.7% by mass of sodium hydroxide, and 2.8% by mass of carbon disulfide was used. As the spinning bath, a Mueller bath containing 100 g / L of sulfuric acid, 15 g / L of zinc sulfate, and 350 g / L of sodium sulfate was used. As the spinning nozzle for discharging viscose, one having 4000 nozzle holes having a hole diameter of 0.06 mm was used.

Stretching was one-stage stretching, and the stretching rate was 40%. Thereafter, in the same manner as in Example 1, the take-up speed with the stretcher roller was 70 m / min, and the yarn was taken up. The taken yarn is scoured in the order of hot water treatment, hydrosulfurization treatment, bleaching, pickling and oiling at 80 ° C., then cut to 10 mm, the fineness is 1.7 dtex, and the fiber length is A rayon fiber of 10 mm was obtained.

(Comparative Example 2)
After cutting to 10 mm, rayon fibers having a fineness of 1.7 dtex and a fiber length of 10 mm were obtained in the same manner as in Comparative Example 1 except that drying was performed at 105 ° C. for 30 minutes.

(Comparative Example 3)
As the viscose, one containing 8.5% by mass of cellulose, 5.7% by mass of sodium hydroxide, and 2.8% by mass of carbon disulfide was used. To this viscose solution, 0.7% of titanium dioxide (15% slurry) was added to cellulose and mixed. As the spinning bath, a Mueller bath containing 100 g / L of sulfuric acid, 15 g / L of zinc sulfate, and 350 g / L of sodium sulfate was used. The temperature of the spinning bath was set to 50 ° C. As the spinning nozzle for discharging the mixed liquid, a nozzle provided with 4000 nozzle holes having a hole diameter of 0.06 mm was used.

The first stretch ratio in the first stage stretching was 42%, and the second stretch ratio in the second stage stretching was 0.7%. Thereafter, in the same manner as in Example 1, the yarn was taken up at a take-up speed of 60 m / min. The taken yarn is heat-treated in hot water at 82 ° C., then scoured in the order of hydrosulfurization, bleaching, pickling and oiling, then cut to 10 mm, and the fineness is 2.2 dtex. A rayon fiber having a fiber length of 10 mm was obtained.

(Comparative Example 4)
After cutting to 10 mm, rayon fibers having a fineness of 2.2 dtex and a fiber length of 10 mm were obtained in the same manner as in Comparative Example 3 except that drying was performed at 105 ° C. for 30 minutes.

(Comparative Example 5)
A fiber for hydrolytic paper (Lyocell, manufactured by Renzing Co., Ltd., fineness 1.4 dtex, fiber length 10 mm) was used.

(Comparative Example 6)
Other than using a spinning nozzle with 4000 nozzle holes having a hole diameter of 0.05 mm, the take-up speed with an extender roller was 60 m / min, and the yarn after scouring was cut to the length shown in Table 2 below Spinning, scouring and drying under the same conditions as in Comparative Example 2 gave a rayon fiber having a fineness of 1.1 dtex and a fiber length of 7 mm.

(Comparative Example 7)
Except for using a spinning nozzle having 4000 nozzle holes with a 0.06 mm diameter, taking up the speed at the stretcher roller to 70 m / min, and cutting the yarn after scouring to the length shown in Table 2 below Spinning, scouring and drying under the same conditions as in Comparative Example 2 gave a rayon fiber having a fineness of 1.7 dtex and a fiber length of 10 mm.

(Comparative Example 8)
Hydrolytic paper fibers (Lyocell, manufactured by Renzing, fineness 2.2 dtex, fiber length 10 mm) were used.

The average crimp rate, average crimp number, crimp space height, L / D, and oil adhesion rate of the fibers of Examples and Comparative Examples were measured and calculated as follows. It is shown in Table 2. Tables 1 and 2 also show the fiber length, fineness, crimp type and shape. Further, the water dispersibility of the fibers of Examples and Comparative Examples was measured and evaluated as follows, and the results are shown in Table 3 below. 1 is a side view photograph of Example 1 observed with a digital microscope (manufactured by KEYENCE, model number “VHX-500F”), and FIG. 2 is a side view photograph of fibers of Comparative Examples 1, 3, and 5. Indicated.

(Average crimp rate)
(1) 20 fibers were arbitrarily extracted from the raw cotton, and each fiber 10 was placed on a black acrylic plate as shown in FIG.
(2) As shown in FIG. 3, the length a (mm) from the end point of the fiber 10 to the end point was measured in each fiber 10 in a state where nothing was covered with the fiber.
(3) The fiber length was L (mm), and the crimp rate of each fiber 10 was determined based on the following formula.
Crimp rate (%) = (La) / L × 100
(4) The average crimp rate of the 20 fibers was calculated and used as the average crimp rate.

(Height of crimp space)
(1) 20 fibers were arbitrarily extracted from the raw cotton, and each fiber 10 was placed on a black acrylic plate, as shown in FIG.
(2) As shown in FIG. 4, a straight line c was drawn on the bottom piece of each crimped portion of each fiber 10 in a state where nothing was covered with the fiber.
(3) As shown in FIG. 4, a perpendicular line d is drawn from the apex of each crimped portion toward the straight line c, and the length h of the perpendicular line d is the height of the crimped space portion. In each fiber, among the heights of all the crimp spaces, the height of the largest crimp space was defined as the height H of the crimp space of the fiber.
(4) The proportion of fibers in which the height of the crimped space in 20 fibers exceeds 0.70 mm or more was calculated.

(Average number of crimps)
(1) 20 fibers were arbitrarily extracted from the raw cotton and placed on a black acrylic plate.
(2) The total number X (crests) of crimp peaks and valleys contained in each fiber was counted.
(3) Each fiber for which the measurement of the total number of crimp peaks and valleys was completed was stretched on the acrylic plate until there was no crimp, and the fiber length Y (mm) after stretching was measured.
(4) Based on the following formula, the number of crimps of each fiber was determined.
Number of crimps (pieces / inch) = (X / 2) × (25.4 / Y)
(5) The average of the number of crimps of 20 fibers was obtained and used as the average number of crimps.

(L / D)
The fiber cross section of the fiber was converted into a perfect circle, the fiber width D was calculated from the cross-sectional area, and L / D was determined.

(Oil agent adhesion rate)
The sample cotton was dried for 2 hours with an air-cooling low-temperature dryer at 105 ° C., and was made into an absolutely dry state (exact dry mass of sample cotton: W1). Next, the sample cotton that had been completely dried was impregnated with methanol, and oil and fat were extracted with a press-type extractor. Methanol was volatilized from the extracted liquid, and the remaining one was evaluated as an extract (mass of oil extract: W2). Using the obtained measured value, the adhesion rate of the oil was calculated by the following formula.
Oil adhesion rate (%) = W2 / W1 × 100

(Water dispersibility)
(1) A stirrer (“Lab-stirlerLT400” manufactured by Yamato Scientific Co., Ltd.) was attached to a water tank (width 100 cm, depth 20 cm, height 60 cm).
(2) After 90 L of water was put in the water tank, raw cotton corresponding to an absolutely dry mass of 4.5 g was introduced from the upper part of the water tank while rotating the stirrer at a rotation speed of 2000 rpm.
(3) The stirrer was stopped 1 minute after the raw cotton was added, the number of fiber lumps immediately after the stirring was stopped was measured, and water dispersibility was evaluated according to the following three-stage criteria.
Good: The fiber lump is less than 20 and water dispersibility is good.
Slightly poor: The fiber mass is 20 or more and less than 25, and the water dispersibility is slightly poor.
Poor: There are 25 or more fiber clumps and water dispersibility is poor.

As can be seen from the results in Table 3, the rayon fibers having the predetermined average crimp rate of Examples 1 to 4 had good water dispersibility even in the dry state. On the other hand, Comparative Examples 1 and 3, which are wet rayon fibers without crimping, have good water dispersibility, while the dry rayon fibers of Comparative Examples 2 and 4, 6 and 7 are water-dispersed. Sex was a little bad. Moreover, the lyocell of Comparative Examples 5 and 8 had poor water dispersibility.

The rayon fibers having a predetermined average crimp rate of Examples 1 to 4 have good water dispersibility even if they do not contain a large amount of water. In addition, it is environmentally friendly because it has a small share of water during transportation, simplifies packaging materials, and can transport more products at one time. In addition, since it does not contain a large amount of water in terms of storage, problems such as mold can be reduced, and long-term storage can be achieved.

(Example B1)
A wet hydroentangled nonwoven fabric was prepared using the fibers of Example 1. A wet papermaking web having a basis weight of about 40 g / m ² was produced using 100% of the fiber of Example 1 as a raw material by a paper machine. Next, a water stream is jetted from a nozzle having a nozzle hole diameter of 0.13 mm arranged at intervals of 1 mm at a water pressure of 2.5 MPa from the web surface, and then dried at 60 ° C. for about 5 minutes by a drier, and wet hydroentangled nonwoven fabric Was made. The fiber of Example B1 had good entanglement at the time of forming the nonwoven fabric.

(Comparative Example B1)
Except for using the fiber of Comparative Example 1, a wet hydroentangled nonwoven fabric made of 100% by mass of the fiber of Comparative Example 1 was produced in the same manner as in Example B1.

(Comparative Example B2)
Except for using the fiber of Comparative Example 3, a wet hydroentangled nonwoven fabric composed of 100% by mass of the fiber of Comparative Example 3 was produced in the same manner as in Example B1.

In Example B1 and Comparative Examples B1 and B2, the surface and cross section of the papermaking web after papermaking and the surface and cross section of the nonwoven fabric after hydroentanglement were observed using a digital microscope (manufactured by KEYENCE, model number “VHX-500F”). did. FIG. 5A shows a surface photograph (100 times) of the papermaking web after papermaking in Example B1, and FIG. 5B shows a cross-sectional photograph (100 times) of the papermaking web after the papermaking. FIG. 5C shows a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Example B1, and FIG. 5D shows a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement. FIG. 6A shows a surface photograph (100 times) of the papermaking web after papermaking in Comparative Example B1, and FIG. 6B shows a cross-sectional photograph (100 times) of the papermaking web after papermaking. FIG. 6C shows a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Comparative Example B1, and FIG. 6D shows a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement. FIG. 7A shows a surface photograph (100 times) of the papermaking web after papermaking in Comparative Example B2, and FIG. 7B shows a cross-sectional photograph (100 times) of the papermaking web after the papermaking. FIG. 7C shows a surface photograph (100 times) of the nonwoven fabric after hydroentanglement in Comparative Example B2, and FIG. 7D shows a cross-sectional photograph (175 times) of the nonwoven fabric after hydroentanglement.

As can be seen from FIG. 5 to FIG. 7, although the natural crimp of the fiber is stretched at the wet papermaking stage, the residual crimp of the fiber was larger in Example B1 than in Comparative Examples B1 and B2. And it was found that when the hydroentanglement treatment was performed, the bent fibers were oriented in the thickness direction.

(Examples C1 to C11)
The regenerated cellulose fibers of Examples 2 to 4 and pulp for hydrolytic paper (average fiber length of 2.8 mm) were put into water in a mixer so as to have the mixing ratio shown in Table 4 below, and stirred with the mixer. The obtained slurry was put into a paper machine filled with water to prepare a wet paper making web having a basis weight shown in Table 4 below. Subsequently, the obtained web was passed through a hydroentanglement machine, and after jetting a high-pressure water stream having a water pressure shown in Table 4 below from one surface of the web by a nozzle in which orifices having a nozzle hole diameter of 0.13 mm were arranged at intervals of 1 mm, The wet entangled nonwoven fabric was produced by drying at 60 ° C. for about 5 minutes with a dryer.

The basis weight and thickness of wet hydroentangled nonwoven fabrics of Examples C1 to C11 were measured and calculated as follows, and the results are shown in Table 4 below. The specific volume was calculated based on the basis weight and thickness of the wet hydroentangled nonwoven fabric, and the results are shown in Table 4 below. Further, the wet tensile strength, the dry tensile strength, the wet tensile elongation, and the dry tensile elongation in the machine direction and the transverse direction of the wet hydroentangled nonwoven fabrics of Examples C1 to C11 were measured and calculated as follows, and the results were as follows: Table 5 shows. Further, the water decomposability of the wet hydroentangled nonwoven fabrics of Examples C1 to C11 was evaluated as follows, and the results are shown in Table 5 below.

(Weight)
Based on JIS L 1913, the measurement was calculated as follows.
The size (width, length) and mass of the wet hydroentangled nonwoven fabric were measured, and the basis weight was calculated based thereon.

(Thickness)
It measured as follows based on JISL1086.
(1) Using a thickness meter (manufactured by Mitutoyo Corporation), the thickness of the nonwoven fabric after 10 seconds was measured under a pressure of 1.96 kPa.
(2) (1) The operation was performed at five locations, and the average of the measured values at the five locations was determined as the thickness.

(Specific volume)
Based on the basis weight and thickness measured and calculated above, the specific volume was determined by the following formula.
Specific volume (cm ³ / g) = [weight per unit area (g / m ² ) / thickness (mm)] × 1000

(Tensile strength and tensile elongation)
The measurement was performed as follows in accordance with JIS P 8135.
1. Measurement condition test piece width: 25 mm
Grasp interval: 100mm
Test speed: 300mm / min
Number of measurements: n = 2
2. Measurement Method (1) Wet Tensile Strength and Wet Tensile Elongation (a) Pure water was poured into a shallow container, and a test piece (25 mm width) was placed and immersed for 1 hour.
(B) After one hour, the test piece was taken out of the container and sandwiched with waste cloth, and lightly pressed from above to remove excess water.
(C) The wet sample obtained in (b) was set in a Tensilon-type tensile tester, and the tensile strength and tensile elongation in the machine direction (MD) and transverse direction (CD) were measured under the above measurement conditions. The measurement was performed twice, and the average values were taken as the wet tensile strength and wet tensile elongation of the nonwoven fabric.
(2) Dry tensile strength and dry tensile elongation A test piece (25 mm width) is set in a Tensilon type tensile tester, and the tensile strength and tensile elongation in the machine direction (MD) and transverse direction (CD) are measured under the above measurement conditions. Was measured. The measurement was performed twice, and the average values were taken as the dry tensile strength and dry tensile elongation of the nonwoven fabric.

(Geometric mean strength and geometric mean elongation)
Based on the dry tensile strength, dry tensile elongation, wet tensile strength, and wet tensile elongation measured and calculated above, the geometric average strength and geometric average elongation were determined by the following formulas.

(Water disintegration)
Water disintegration was evaluated using a shaker.
(1) A nonwoven fabric was cut into 10 cm square to obtain a sample.
(2) Put 200 mL of tap water and a cut sample into a 500 mL separatory funnel.
(3) The separating funnel was set in a shaker (manufactured by Yamato Scientific Co., Ltd., model number “SA300 type”), and horizontal shaking was started at 300 rpm.
(4) The sample state after 10 minutes was visually observed and evaluated according to the following four-step criteria.
A: Almost all of the sample is disintegrated into fibers.
B: The sample is disintegrated and sample pieces and fibers are mixed.
C: A part of the sample is broken, but the sample form is maintained.
D: The sample has not collapsed.

The cross section of the hydroentangled nonwoven fabric of Example C9 was observed with an electron microscope (manufactured by Hitachi, Ltd., model number “S-3500N”), and a cross-sectional photograph (40 ×) is shown in FIG. As can be seen from FIG. 8, the fiber directions in the nonwoven fabric were different in both the MD direction and the CD direction, and had three-dimensional confounding properties.

The wet nonwoven fabrics of Examples C1 to C9 had high wet tensile strength and dry tensile strength, and the nonwoven fabric was strong. Further, the wet tensile elongation and the dry tensile elongation are high, the texture is soft, and the touch is good.

The wet hydroentangled nonwoven fabrics of Examples C1 to C13 are impregnated with a chemical solution containing a moisturizing component and a cleaning component so as to be about 300% by mass with respect to 100% by mass of the nonwoven fabric, and are stored in a container, and then hydrolyzed. A sheet product was obtained. All the nonwoven fabrics had sufficient wet strength and water disintegration performance to be used as water disintegration paper.

The rayon fiber for wet nonwoven fabric of the present invention and the wet nonwoven fabric including the same can be used for nursing care products, sanitary products, diapers, cleaning articles, cleaning sheets, and the like.

Claims

A rayon fiber for wet nonwoven fabric, wherein the average crimp rate is 16% or more and 45% or less.
The rayon fiber for wet nonwoven fabric according to claim 1, wherein the crimped space portion contains more than 5% of fibers having a height of 0.70 mm or more.
3. The rayon fiber for wet nonwoven fabric according to claim 1 or 2, wherein the average number of crimps is 3 / inch or more and 25 / inch or less.
The rayon fiber for wet nonwoven fabric according to any one of claims 1 to 3, wherein the ratio L / D of the fiber length L to the fiber width D is 350 or more and 1200 or less.
The rayon for wet nonwoven fabric according to any one of claims 1 to 4, wherein the oil agent is attached to the rayon fiber for wet nonwoven fabric in an amount of 0.03% by mass to 0.2% by mass with respect to the total mass of the fiber. fiber.
The rayon fiber for wet nonwoven fabric according to claim 5, wherein the oil agent is a polyoxyethylene ester nonionic surfactant.
In a method of producing a rayon fiber for wet nonwoven fabric by discharging viscose into a spinning bath from a spinning nozzle, forming a yarn by coagulating and regenerating the viscose, drawing the yarn, drawing and scouring ,
The stretching is a two-stage stretching, the stretching ratio in the first stage stretching is 30% or less, and the stretching ratio in the second stage stretching is 3.0% or less, so that the average crimp ratio is 16% or more and 45 A method for producing a rayon fiber for wet nonwoven fabric, wherein the rayon fiber for wet nonwoven fabric is at most%.
The method for producing a rayon fiber for wet nonwoven fabric according to claim 7, wherein the stretched yarn is cut into a predetermined fiber length before scouring.
A wet nonwoven fabric comprising the rayon fiber for wet nonwoven fabric according to any one of claims 1 to 6.
The wet nonwoven fabric according to claim 9, wherein the wet nonwoven fabric contains 5 to 95 mass% of rayon fiber for wet nonwoven fabric and 5 to 95 mass% of pulp with respect to 100 mass% of wet nonwoven fabric.
The wet nonwoven fabric according to claim 9 or 10, wherein the wet nonwoven fabric is a wet hydroentangled nonwoven fabric.
A step of producing a wet papermaking web with a wet papermaking machine, wherein the mixture comprising the rayon fiber for wet nonwoven fabric according to any one of claims 1 to 6 and pulp;
The manufacturing method of the wet nonwoven fabric including the process of spraying a water flow on the surface of at least one of the said wet papermaking web, and performing a hydroentanglement.
A hydrolytic paper comprising the wet nonwoven fabric according to any one of claims 9 to 11.