JP2021030191A - Manufacturing method of non-woven fabric and non-woven fabric manufactured by the manufacturing method - Google Patents

Abstract

To provide a manufacturing method of non-woven fabric which has uniformity of an applied hydrophilizing agent in order to improve permeability of the non-woven fabric, and to provide the non-woven fabric manufactured by the manufacturing method.SOLUTION: In a process of preparing a coating liquid of a manufacturing method of non-woven fabric, dilution water has electric conductivity of 0.3 mS/m or less. When the electric conductivity of dilution water is 0.3 mS/m or less, relatively small amount of Ca ion (+) remains in the dilution water. In the coating liquid provided by diluting a hydrophilizing agent with the dilution water, the hydrophilizing agent provided with anion (-) on a hydrophilic portion which is adsorbed onto Ca ion (+) decreases as a whole and, therefore, the hydrophilizing agent in the coating liquid can be uniformly dispersed. Accordingly, by applying the coating liquid onto the surface of non-woven fabric, uniformity of the applied hydrophilizing agent is secured and the permeability can be improved.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method for producing a non-woven fabric including a step of preparing a coating liquid, and a non-woven fabric produced by this production method.

Nonwoven fabrics are used in the fields of sanitary products such as diapers, sanitary napkins, and armpit sweat pads, and disposable clothing, and are often used as surface materials that come into contact with the user's skin. Nonwoven fabrics used as surface materials for diapers and the like are required to have permeability so that body fluids such as urine and blood can be smoothly absorbed by absorbers and the like.

In order to use a hydrophobic non-woven fabric for such an application, it is necessary to apply a hydrophilic treatment to impart permeability. In this hydrophilization treatment, it is desired to ensure the uniformity of the hydrophilic agent applied to the non-woven fabric and improve the permeability.

Here, for example, in Patent Document 1, a non-woven fabric to be hydrophilized, the viscosity (for example, concentration and temperature) of the coating liquid is adjusted, the permeation speed of the coating liquid is increased, and a roller or the like is used. It is disclosed that the coating liquid is uniformly applied to the surface of the non-woven fabric by the coating method or the spraying method.

International Publication No. 2013/065794

However, even if the coating liquid is uniformly applied to the surface of the non-woven fabric as in Patent Document 1, the hydrophilic agent applied to the non-woven fabric is actually biased, so that the permeability of the non-woven fabric is improved. It was difficult.

Therefore, an object of the present invention is to provide a method for producing a nonwoven fabric having the uniformity of the applied hydrophilic agent and a nonwoven fabric produced by this manufacturing method in order to improve the permeability of the nonwoven fabric.

In order to solve the above problems, a step of diluting the hydrophilic agent with diluting water to prepare a coating liquid, a step of applying the coating liquid to the non-woven fabric, and drying the non-woven fabric to which the coating liquid is applied are dried. In the method for producing a non-woven fabric including the step of making the coating liquid, the diluted water used in the step of preparing the coating liquid has an electric conductivity of 0.3 mS / m or less.

Further, the method for producing the nonwoven fabric may be characterized in that the dilution concentration of the hydrophilic agent in the step of preparing the coating liquid is 0.1 to 5.0% by mass.

Further, the method for producing the non-woven fabric may be characterized in that the non-woven fabric is a spunbonded non-woven fabric.

Further, the method for producing the non-woven fabric may be characterized in that the step of applying the coating liquid to the non-woven fabric is a foam coating process.

Further, the method for producing the nonwoven fabric may be characterized in that the dynamic surface tension S100 at a foam life of 100 ms by the maximum valve point method of the coating liquid is 36 mN / m or less.

Further, the method for producing the nonwoven fabric may be characterized in that the thermoplastic resin constituting the nonwoven fabric is a polyolefin resin.

Further, it may be a non-woven fabric manufactured by using the above-mentioned non-woven fabric manufacturing method.

According to the present invention, in order to improve the permeability of the non-woven fabric, it is possible to provide a method for producing a non-woven fabric having uniformity of the applied hydrophilic agent and a non-woven fabric produced by this production method.

It is the schematic which shows an example of the nonwoven fabric manufacturing apparatus which concerns on one Embodiment of this invention. It is the schematic explaining the hydrophilic agent coating apparatus shown in FIG.

An embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. However, the present invention is not limited to the aspects of the present embodiment.

<Non-woven fabric manufacturing equipment and manufacturing method>
FIG. 1 is a schematic view showing an example of a nonwoven fabric manufacturing apparatus 100 according to an embodiment of the present invention. Here, the arrows A in the drawing represent the circumferential direction of the conveying belt 11, and the white arrows B and C in the drawing represent the conveying directions of the non-woven fabric original fabric 1 and the non-woven fabric 2, respectively. Further, the X-axis direction in the drawing indicates the transport directions B and C, and the Z-axis direction is orthogonal to the X-axis direction and indicates a direction parallel to the blowing direction of the drying air 41. ..

The non-woven fabric manufacturing apparatus 100 includes a conveyor 10, a thermal embossing roll 20, a hydrophilic agent coating apparatus 30, a dryer 40, and a winder 50.

First, the conveyor 10 includes a conveyor belt 11 and first to fourth rolls 12 to 15 hung around the apex of the inverted trapezoidal orbit of the conveyor belt 11. The transport belt 11 moves clockwise in the orbital direction A with at least one drive rotation of the first to fourth rolls 12 to 15. The non-woven fabric raw fabric 1 supplied on the transport belt 11 is transported to the heat embossing roll 20 in the transport direction B.

The conveyor 10 according to the present embodiment preferably has a transport speed of 10 to 1000 (m / min), more preferably 100 to 800 m / min.

(Non-woven fabric)
The non-woven fabric raw fabric 1 is not particularly limited, and a known non-woven fabric can be used. The main component of the non-woven fabric is not particularly limited, and is preferably a polyolefin resin or a polyester resin which is a hydrophobic resin. Since it is chemically stable and has high safety, it may be a polyolefin resin as a sanitary material. More preferred. Further, the non-woven fabric may contain a hydrophilic resin. In the present embodiment, the non-woven fabric preferably contains 50% by mass or more of the polyolefin resin, more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Examples of the polyolefin resin include polypropylene and polyethylene, and polypropylene is preferable from the viewpoint of spinnability and strength.

The method for producing the non-woven fabric is not particularly limited, and a non-woven fabric produced by a known production method can be used. In the present embodiment, the non-woven fabric is preferably a spunbonded non-woven fabric because the flexibility and strength are well-balanced, the productivity is high, and there is an advantage in terms of cost. More preferably, it is a spunbonded non-woven fabric in which polyolefin long fibers (preferably polypropylene long fibers) or polyester long fibers are integrated from the viewpoint of spinnability of the long fibers.

The weight of the non-woven fabric used is about ^{10 to 50 g / m 2.} This non-woven fabric has high flexibility when the basis weight is 50 g / m ² or less, and the tensile strength is improved when the basis weight is 10 g / m ² or more, and is preferably used as a surface material for sanitary materials.

The thermal embossing roll 20 includes a pair of cylindrical rolls having an uneven cylindrical surface heated to a predetermined temperature and a flat cylindrical surface. The pair of cylindrical rolls squeeze the non-woven fabric 1 and partially entangle it with pressure and heat to form the non-woven fabric 2. This entanglement treatment is also called a thermal embossing method, and the non-woven fabric 2 obtained by this method has an embossed pattern appearing on the surface.

In addition to the heat embossing method, the non-woven fabric 2 according to the present embodiment employs a method using means such as needle punching, a water jet, or ultrasonic waves, or a method of heat-sealing by hot air through as a method of fiber entanglement treatment. can do. The needle punching means is a method in which a needle is inserted into a fiber assembly and entangled. The water jet means is a method of injecting high-pressure water onto a fiber assembly to entangle it. The ultrasonic means is a method of melting and entwining some fibers by using ultrasonic waves. Hot air through is a method in which hot air is blown onto fibers to melt and entangle some of the fibers.

Although the details of the hydrophilic agent coating device 30 will be described later, the coating liquid is provided with a coating head 36, and the coating liquid is made into a foam cream on the lower surface of the non-woven fabric 2 moving in the transport direction C via the coating head 36. Apply foaming liquid.

The dryer 40 is a through-air type dryer, in which the drying air 41 is blown downward, and the non-woven fabric 2 coated with the effervescent liquid is dried with hot air while being conveyed to obtain a hydrophilic non-woven fabric 3. The drying conditions are not particularly limited, and drying can be performed under known conditions. As for the drying temperature, the hot air drying temperature (temperature measured by a thermocouple) is preferably 80 to 120 ° C, more preferably 90 to 110 ° C.

The dryer 40 according to the present embodiment is a through-air dryer, but is not limited to this, and may be, for example, a cylinder dryer, a Yankee dryer, an infrared heater, or the like.

The winder 50 winds up the hydrophilic non-woven fabric 3 with a predetermined winding hardness without causing wrinkles.

<Hydrophilic agent coating device and coating method>
FIG. 2 is a schematic view illustrating the hydrophilic agent coating device 30 shown in FIG. Here, (1) to (3) in the figure represent each hydrophilic agent coating step.

The hydrophilizing agent coating device 30 dilutes the raw material tank 31 (see (1) the step of adding the hydrophilizing agent in FIG. 2) and the dilution tank 32 ((2) the hydrophilizing agent in FIG. 2 with diluting water). A service tank 33, a liquid feed pump 34, a foaming machine 35, and a foam coating head 36 (see the process of applying the coating liquid to the non-woven fabric in FIG. 2).

(1) Step of adding the hydrophilic agent (1) In the step of adding the hydrophilic agent, the hydrophilic agent is charged into the raw material tank 31.

(Hydrophilic agent)
The hydrophilic agent is not particularly limited, and when it is applied to the non-woven fabric 2, it is preferable that the hydrophilic non-woven fabric 3 can be formed, and it is more preferable that the non-woven fabric 2 can be imparted with liquid permeability. As the hydrophilic agent, it is preferable to use one having a large surface tension lowering effect. For example, an amine oxide type hydrophilic agent, an anionic hydrophilic agent such as potassium alkyl phosphate or sodium dialkyl sulfosuccinate, or a nonionic hydrophilic agent such as ether type silicone is preferable, and an amine oxide type hydrophilic agent is more preferable. .. As the amine oxide type hydrophilic agent, an alkylamine oxide or an alkenylamine oxide having an alkyl group or an alkenyl group having 1 or more carbon atoms and 24 or less carbon atoms is preferable. As a more preferable amine oxide, an amine oxide represented by the following general formula (A1) can be mentioned.

[In the formula, R1a represents an alkyl group or an alkenyl group having 8 or more carbon atoms and 24 or less carbon atoms, and R2a and R3a represent the same or different alkyl groups having 1 or more carbon atoms and 3 or less carbon atoms, respectively. , -NHC (= O) -group or -C (= O) NH- group, E represents an alkylene group having 1 or more carbon atoms and 5 or less carbon atoms, and m and n are m = 0 and n = 0 or It shows m = 1 and n = 1. ]

In the above general formula (A1), R1a is an alkyl group having 8 or more carbon atoms and 24 or less carbon atoms or an alkenyl group, but an alkyl group having 12 or more carbon atoms and 18 or less carbon atoms is preferable. R2a and R3a are alkyl groups having 1 or more carbon atoms and 3 or less carbon atoms, respectively, but a methyl group having 1 carbon atom is preferable. Further, in the above general formula (A1), m and n are preferably m = 0 and n = 0.

Among them, as the amine oxide type hydrophilic agent, an alkyldimethylamine oxide having an alkyl group having 8 or more carbon atoms and 24 or less carbon atoms is preferable, and an alkyldimethylamine oxide having an alkyl group having 10 or more carbon atoms and 14 or less carbon atoms is more preferable. Alkyldimethylamine oxide having an alkyl group having 12 or more carbon atoms and 14 or less carbon atoms is more preferable, and lauryldimethylamine oxide is even more preferable.

As the hydrophilic agent, a commercially available product can also be used. For example, lauryldimethylamine N-oxide (manufactured by Kao Corporation, Anchor 20N) can be preferably used.

When a non-woven fabric is used as a surface material of a sanitary material, it is preferable to use a non-woven fabric and a hydrophilic agent whose hypoallergenicity has been confirmed by a patch test or the like.

(2) Step of diluting the hydrophilizing agent with diluting water (2) In the step of diluting the hydrophilizing agent with diluting water, the hydrophilizing agent is sent to the dilution tank 32, and the hydrophilizing agent is diluted with diluting water. Then prepare the coating solution.

Here, it is desired to uniformly apply the coating liquid to the surface of the non-woven fabric 2 to improve the permeability of body fluids such as urine and blood. However, in reality, since the hydrophilic agent is non-uniformly applied to the surface of the non-woven fabric 2, it is difficult to ensure the uniformity of the hydrophilic agent in the hydrophilic non-woven fabric 3 and to improve the permeability. Was there.

Therefore, the inventors focused on (2) the step of diluting the hydrophilic agent with diluting water, and the hydrophilic agent aggregated with the ions contained in the diluted water, so that the hydrophilic agent in the coating liquid was not used. It was clarified that it was uniformly dispersed.

(Diluted water)
The diluted water is obtained by passing tap water or the like through each of the ion exchange resin for removing ions and the filter for removing impurities. However, even if the diluted water is passed through the ion exchange resin and the filter, the diluted water can be used. , Mainly, many Ca ions remain. The electrical conductivity (mS / m) of the diluted water is used as one of the indexes of the amount of residual ions in the diluted water.

(About the aggregation mechanism of the hydrophilic agent)
While the diluted water contains many Ca ions (cations), some hydrophilic agents have anionic (anion) or nonionic (nonionic) properties in the hydrophilic portion. The hydrophilic portion of the hydrophilic agent having an anion (anion) is adsorbed by Ca ions (cations), so that the hydrophilic agent in the coating liquid is aggregated.

Therefore, in the present embodiment, the electric conductivity (mS / m) is used as an index of the amount of ions in the diluted water, and the electric conductivity (mS / m) of the diluted water is set to a predetermined value or less for coating. By reducing the salt concentration of Ca ions (cations) and the like in the liquid, it was possible to uniformly disperse the hydrophilic agent in the coating liquid.

(3) Step of applying the coating liquid to the non-woven fabric In the step of (2) Diluting the hydrophilic agent with diluting water, the hydrophilic agent can be uniformly dispersed in the coating liquid, so that compared with the conventional case. It has become possible to secure the uniformity of the hydrophilic agent in the hydrophilic non-woven fabric 3 and improve the permeability.

However, depending on the coating method in the step of applying the coating liquid to the non-woven fabric (3), the hydrophilic agent may still be non-uniformly applied to the surface of the non-woven fabric 2, so that the hydrophilic agent in the hydrophilic non-woven fabric 3 is still applied. It is required to further secure the uniformity of. At the same time, when the non-woven fabric 2 coated with the coating liquid is dried, it is required to dry it with a drying load as small as possible in order to shorten the drying time and reduce the equipment cost.

Here, in order to solve the new problems of further uniformity of the hydrophilizing agent and drying with a smaller drying load in the non-woven fabric coated with the coating liquid, the coating liquid (3) of the present embodiment is solved. The foam coating method is adopted as the coating method in the step of coating the non-woven fabric, and the step of forming the foaming liquid (3-1) and the step of applying the foaming liquid to the non-woven fabric are provided. .. In the step of applying this coating liquid to the non-woven fabric, for example, a foam coating machine manufactured by Gaston County Dying Machine can be used. As a result, although details will be described later, by adopting the foam coating method, it is possible to suppress coating unevenness, further secure the uniformity of the hydrophilic agent in the hydrophilic non-woven fabric 3, and reduce the drying load. ..

In the step of applying the coating liquid of the present embodiment to the non-woven fabric, the foam coating method is adopted as the coating method, but the coating method is not limited to this, for example, a spray method for spraying the coating liquid on the fibers, a roller, or the like. A coating method in which the coating liquid is applied to the fibers using the coating liquid and a dipping method in which the fibers are immersed in the coating liquid may be adopted.

(3-1) Step of Forming Foaming Liquid In the step of forming the foaming liquid, the liquid feeding pump 34 sends the coating liquid temporarily stored in the service tank 33 to the foaming machine 35. The foaming machine 35 forms a foaming liquid from the coating liquid. The foaming machine 35 is provided with, for example, a pin-type mixer, and forms a foaming liquid by stirring the gas and the coating liquid.

<Effervescent liquid>
The foaming liquid is foamy cream-like like the foamy substance "mouse", and when the foaming liquid is applied to the non-woven fabric, the foaming liquid exists in the form of a thin film on the surface of the non-woven fabric 2 and constitutes the non-woven fabric 2. The foaming liquid permeates into the non-woven fabric 2 due to the capillary phenomenon due to the fiber gaps. In order to uniformly apply the hydrophilic agent to the surface of the non-woven fabric 2, the foam cream-like effervescent liquid is required not to disappear immediately after being applied to the surface of the non-woven fabric. Here, in the case of foaming, which is a dynamic change, when the hydrophilic agent is slowly oriented at the interface of the bubbles and the surface tension of the coating liquid is high, the foaming property of the coating liquid is low and bubbles are formed. It becomes difficult for creamy foaming liquid to be formed.

Therefore, in the present embodiment, the dynamic surface tension S100 (mN / m) at the bubble life of 100 (ms) of the coating liquid is used as an index of the foaming property of the coating liquid, and the dynamic surface of the coating liquid is used. By setting the tension S100 (mN / m) to a predetermined value or less, bubbles are stably present even after being applied to the surface of the non-woven fabric 2, and the uniformity of the hydrophilic agent applied to the hydrophilic non-woven fabric 3 is improved. Improved.

(3-2) Step of Applying Foam Liquid to Non-woven Fabric In the step of applying the foam liquid to the non-woven fabric 2, the foam coating head 36 applies the foam liquid to the lower surface of the non-woven fabric 2. The foam coating head 36 includes, for example, a slit die having a slit-shaped opening, and discharges a band-shaped or streak-shaped foam liquid having the same width as the slit spacing from the slit to convey the foam in the transport direction C (FIG. FIG. 1) is applied to the lower surface of the non-woven fabric 2 that moves. The slit spacing (width of the opening) in the slit die of the present embodiment is preferably 1 to 10 (mm), more preferably 2 to 8 (mm), and 3 to 5 (mm). Is particularly preferable.

Here, for the coating liquid that is the source of the effervescent liquid, if the concentration of the hydrophilic agent with respect to the coating liquid, that is, the dilution concentration (mass%) of the hydrophilic agent is relatively low, the hydrophilic treatment is performed. Since the amount of coating required for this is increased, the drying load is increased, and the non-woven fabric 2 coated with the hydrophilic agent may be insufficiently dried. On the other hand, when the dilution concentration (mass%) of the hydrophilic agent is relatively high, the hydrophilic non-woven fabric 3 causes transfer of the hydrophilic agent to another hydrophobic sheet or the user, resulting in unintended hydrophilicization or skin. It may cause irritation such as rash and rash on the surface.

Therefore, in the present embodiment, the dilution concentration (% by mass) of the hydrophilic agent is set within a predetermined range to reduce the drying load and improve the transfer resistance of the hydrophilic agent by the hydrophilic non-woven fabric 3.

<Comparative evaluation of diluted water, hydrophilic agent, coating liquid and coating method>
Comparison of nine parameters related to physical properties with respect to Comparative Example 1 and Comparative Example 4 in the diluted water, hydrophilicizing agent, coating liquid and coating method according to each of Examples 1 to 11 of the present invention. Evaluation was performed. This comparative evaluation is shown in Table 1 below. Here, as a common condition in the comparative evaluation, a polypropylene resin spunbonded non-woven fabric (grain size 17.5 g / m ² ) was used as the non-woven fabric raw fabric 1. Further, the transport speed of the non-woven fabric 2 was set to be constant (200 (m / min)).

<Evaluation of uniformity of applied hydrophilic agent>
In the "evaluation of the uniformity of the applied hydrophilic agent", the hydrophilic non-woven fabric 3 was randomly sampled at 5 locations by 2.5 g at different locations in the plane, and was manufactured by MQC (Oxford Instrument). , NMR measuring device). A calibration curve was prepared in advance for each hydrophilic agent, the coating amount was quantified, and the average value and standard deviation of the coating amount of the hydrophilic agent were calculated. The value of "uniformity" (%) was used as an index. The "uniformity" (%) is a value calculated by the formula (100% x standard deviation / average value). The evaluation criteria are four-grade evaluation. If the uniformity is 2 (%) or more, it is "x", if it is 1 (%) or more and less than 2 (%), it is "△", and if the uniformity is 0.5 (%) or more, 1 ( If it is less than%), it is evaluated as "○", and if it is less than 0.5 (%), it is evaluated as "◎".

<Evaluation of drying load>
In the "evaluation of drying load", the drying time (ms) required for the non-woven fabric coated with the hydrophilic agent to be dried and to ^{reach a predetermined basis weight of 18 (g / m 2) was measured.} The evaluation standard is a four-step evaluation. If the drying time is 1000 (ms) or more, it is "x", if it is 100 (ms) or more and less than 1000 (ms), it is "Δ", and if it is 20 (ms) or more and 100 (ms). If it is less than, it is evaluated as "○", and if it is less than 20 (ms), it is evaluated as "◎".

<Evaluation of transfer resistance of the applied hydrophilicizing agent>
"Evaluation of transfer resistance of the applied hydrophilic agent" indicates how difficult it is for the hydrophilic agent in the hydrophilic non-woven fabric 3 to be transferred. Regarding the specific "evaluation of transfer resistance of the applied hydrophilic agent", first, four sheets of 20 cm square are sampled from ^{the non-woven fabric (weight: 17 g / m 2) to which the hydrophilic agent is applied.} Next, prepare four sheets of non-woven fabric ( ^{grain size 17 g / m 2} , water pressure resistance: 150 mmH ₂ O) and paper to which the hydrophilic agent is not applied, each in a 20 cm square, and apply the hydrophilic agent to the non-woven fabric. Four sets of non-woven fabric to which the hydrophilizing agent is not applied and paper are stacked in this order, and a weight of 5 kg is placed on the non-woven fabric having an area of 15 cm square. Then, after allowing to stand at room temperature for 2 weeks, the water pressure resistance (mmH ₂ O) of the non-woven fabric to which the hydrophilic agent was not applied was measured. The amount of decrease in water pressure resistance (mmH ₂ O) before and after this standing was used as an index showing the transfer resistance of the applied hydrophilicizing agent. The evaluation standard is a four-stage evaluation, and if the amount of decrease in water pressure resistance is 30 (mmH ₂ O) or more, it is "x", and if it is 10 (mmH ₂ O) or more and _{less than 30 (mmH 2} O), it is "△". If it was 5 (mmH ₂ O) or more and _{less than 10 (mmH 2} O), it was evaluated as “◯”, and if it was less than _{5 (mmH 2 O), it was evaluated as “⊚”.}

<About the electrical conductivity of diluted water>
The electric conductivity (mS / m) in the diluted water was measured with respect to the diluted water using an electric conductivity meter (ES-71 manufactured by Horiba Seisakusho Co., Ltd.). The electrical conductivity (mS / m) in the diluted water is used as an index of the amount of residual ions contained in the diluted water, and is a parameter that affects the "evaluation of the uniformity of the applied hydrophilic agent". ..

The electrical conductivity of the diluted water of the present embodiment (see Table 1) is preferably 0.3 (mS / m) or less, more preferably 0.1 (mS / m) or less, and 0. It is more preferably 08 (mS / m) or less. Here, when the electrical conductivity of the diluted water is 0.3 (mS / m) or less, a relatively small amount of Ca ions (+) remain in the diluted water. Therefore, in the coating liquid obtained by diluting the hydrophilic agent with this diluted water, there are few hydrophilic agents having an anion (-) in the hydrophilic portion, which is adsorbed by Ca ions (+). The agent can be uniformly dispersed, and the "evaluation of the uniformity of the applied hydrophilic agent" can be improved. Here, when the electric conductivity of the diluted water is 0.1 (mS / m) or less or 0.08 (mS / m) or less, the effect of uniformly dispersing the hydrophilic agent in the coating liquid is more effective. Since it appears more prominently, the "evaluation of the uniformity of the applied hydrophilic agent" can be further improved. The lower limit of the electric conductivity of the diluted water in this embodiment is 0.0055 (mS / m).

<Types of hydrophilic agents>
The type of hydrophilic agent is hydrophilic agent A: lauryldimethylamine N-oxide (manufactured by Kao Corporation, Anchtor 20N) or hydrophilic agent B: polyoxyethylene lauryl ethane triethanolamine (Kao Corporation). Manufactured by Emar 20T).

<Dilution concentration of hydrophilic agent>
The dilution concentration (% by mass) of the hydrophilic agent indicates the concentration of the hydrophilic agent with respect to the coating liquid, and is referred to as "coating amount", "evaluation of drying load" and "transfer resistance of the applied hydrophilic agent". It is a parameter that affects the "evaluation of".

The dilution concentration of the hydrophilic agent of the present embodiment (see Table 1) is preferably 0.1 to 5.0 (mass%). Here, when the dilution concentration of the hydrophilic agent is 0.1 (mass%) or more, the amount of coating required for the hydrophilic treatment can be reduced, so that the drying time (ms) is shortened, and the “drying load” is reduced. "Evaluation of" can be improved. On the other hand, when it is 5.0 (mass%) or less, an increase in the dilution concentration of the hydrophilic agent can be suppressed, so that "evaluation of transfer resistance of the applied hydrophilic agent" can be improved. As a result, the non-woven fabric coated with the hydrophilic agent comes into contact with other hydrophobic sheets or users, causing the other hydrophobic sheets to become hydrophilic and causing inflammation such as rashes and rashes on the skin surface. Can be suppressed.

<Dynamic surface tension of coating liquid>
The dynamic surface tension S100 of the coating liquid is 25 ° C., and the bubble generation interval (bubble plate) 20 to 20 to 25 ° C. using a bubble pressure type dynamic surface tension meter (BP-2, manufactured by KURSS) for the prepared coating liquid. The dynamic surface tension was measured in the range of 1000 msec, and the measured value of the dynamic surface tension at the bubble life of 100 msec was read. The dynamic surface tension S100 of this coating liquid is a parameter that affects the "evaluation of the uniformity of the applied hydrophilic agent".

The dynamic surface tension S100 (see Table 1) of the coating liquid of the present embodiment is preferably 36 (mN / m) or less. Here, when the dynamic surface tension S100 of the coating liquid is 36 (mN / m) or less, the hydrophilic agent is quickly oriented at the interface of the bubbles and the surface tension of the coating liquid becomes low, so that the coating liquid Foaming property becomes high. In particular, when applied by foam coating having a dynamic change, a foam cream-like foaming liquid is likely to be formed, and the hydrophilic agent is uniformly applied to the non-woven fabric 2, that is, "applied hydrophilicization". "Evaluation of the uniformity of the agent" can be improved.

<About the amount of coating liquid applied>
The coating amount (wt%) of the coating liquid indicates the weight ratio of the applied coating liquid to the spunbonded non-woven fabric (weight of 17.5 g / m ^{2), which affects the "evaluation of drying load".} It is a parameter.

(Amount of foaming liquid applied)
In the non-woven fabric, the amount of the foaming liquid applied is preferably 100 (wt%) or less, more preferably 3 to 80 (wt%), and 5 to 60 (wt%) from the viewpoint of drying load. Is particularly preferable. It is preferable to adjust the coating amount so as not to increase the drying load while exhibiting the functions required for the product.

<About coating method>
As the coating method, foam coating or spray coating was used. This coating method is a parameter that affects the "evaluation of the uniformity of the applied hydrophilizing agent".

<Comparative evaluation results for diluted water, hydrophilic agent, coating liquid and coating method>
As is clear from the comparison of the evaluations of Examples 1 to 11, if the electric conductivity of the diluted water is 0.3 (mS / m) or less, the coating liquid obtained by diluting the hydrophilic agent with the diluted water. In the above, since it is possible to reduce the amount of the hydrophilic agent having an anion (-) in the hydrophilic portion, which is adsorbed by a relatively small amount of Ca ions (+) remaining in the diluted water, "the applied hydrophilic agent The "evaluation of uniformity" was "Δ" or higher, and it was concluded that it could be improved.

Here, the electrical conductivity of the diluted water is 0.1 (mS / m) or less (see Examples 1-2, 4-9, 11), preferably 0.08 (mS / m) or less (Example). In the case of 4 and 11), the effect of uniformly dispersing the hydrophilizing agent in the coating liquid appears more remarkably, so that the "evaluation of the uniformity of the applied hydrophilizing agent" becomes "◎". It can be improved further.

If the dilution concentration of the hydrophilizing agent is 0.1 to 5.0 (mass%), the coating amount (wt) required for the hydrophilization treatment depends on the lower limit (0.1 (mass%)). %) And the upper limit (5.0 (% by mass)) can suppress the increase in the dilution concentration of the hydrophilic agent. Therefore, "evaluation of drying load" and "applied hydrophilic agent" "Evaluation of transfer resistance" is "Δ" or more, and can be improved in a well-balanced manner (see Examples 1-5, 8-9, 11).

Further, when the dynamic surface tension S100 of the coating liquid is 36 (mN / m) or less, the coating liquid can exist stably even after being applied to the surface of the non-woven fabric. The "evaluation of the uniformity of the agent" is "○" or higher, which can be improved (see Examples 1-4 and 7).

On the other hand, in Comparative Examples 1 to 4, since the electric conductivity of the diluted water is outside the preferable numerical range (more than 0.3 (mS / m)), the diluted water is similar to the problem that has occurred in the past. In the coating liquid obtained by diluting the hydrophilic agent with, the hydrophilic portion of the hydrophilic agent having anionicity (anion) is adsorbed by Ca ions (cations), and thus the hydrophilicity in the coating liquid. Since the agent is aggregated, the "evaluation of the uniformity of the applied hydrophilic agent" is "x", and the applied hydrophilic agent is non-uniformly present on the surface of the non-woven fabric. Further, in Comparative Examples 1 to 4, since the concentration of the hydrophilic agent is uneven on the surface of the nonwoven fabric coated with the hydrophilic agent, a region where the concentration of the hydrophilic agent is locally high is generated. Since transfer of the hydrophilic agent to other hydrophobic sheets or users occurs from this region where the concentration of the hydrophilic agent is locally high, "evaluation of transfer resistance of the applied hydrophilic agent" is "evaluation of transfer resistance". It is "x".

<Others>
The present invention is not limited to the above-described embodiments, examples, and modifications described therein, and can be appropriately modified or modified without departing from the technical idea of the present invention.

1 Non-woven fabric 2 Non-woven fabric 3 Hydrophilic non-woven fabric 10 Conveyor conveyor 11 Conveyor belt 12 1st roll 13 2nd roll 14 3rd roll 15 4th roll 20 Thermal embossing roll 30 Hydrophilicizing agent coating device 31 Raw material tank 32 Diluting tank 33 Service tank 34 Liquid transfer pump 35 Foaming machine 36 Foam coating head 40 Dryer 41 Drying air 50 Winder 100 Non-woven fabric manufacturing equipment

Claims (7)

The process of diluting the hydrophilic agent with diluting water to prepare the coating liquid, and
The process of applying the coating liquid to the non-woven fabric and
The step of drying the non-woven fabric to which the coating liquid is applied, and
It is a manufacturing method of a non-woven fabric provided with
A method for producing a non-woven fabric, wherein the diluted water used in the step of preparing the coating liquid has an electric conductivity of 0.3 mS / m or less. The method for producing a nonwoven fabric according to claim 1, wherein the dilution concentration of the hydrophilic agent in the step of preparing the coating liquid is 0.1 to 5.0% by mass. The method for producing a non-woven fabric according to claim 1 or 2, wherein the non-woven fabric is a spunbonded non-woven fabric. The method for producing a non-woven fabric according to any one of claims 1 to 3, wherein the step of applying the coating liquid to the non-woven fabric is by foam coating. The method for producing a non-woven fabric according to claim 4, wherein the dynamic surface tension S100 at a foam life of 100 ms by the maximum valve point method of the coating liquid is 36 mN / m or less. The method for producing a non-woven fabric according to any one of claims 1 to 5, wherein the thermoplastic resin constituting the non-woven fabric is a polyolefin resin. A non-woven fabric produced by using the method for producing a non-woven fabric according to any one of claims 1 to 6.

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