JP2023031566A - Method and apparatus for manufacturing nonwoven fabric - Google Patents

Abstract

To provide a manufacturing method and a manufacturing apparatus capable of manufacturing a nonwoven fabric, capable of inhibiting fibers from falling off in both a dry state and a wet state, and capable of continuous production while suppressing contamination caused by added chemicals.SOLUTION: There is provided a method for manufacturing a nonwoven fabric containing a pulp fiber web produced by an air-laid method, comprising: a hydroentangling step of hydroentangling the pulp fiber web; and an adding step of adding a wet paper strengthening agent and an anionic water-soluble polymer to the pulp fiber web after the hydroentangling step. The wet paper strengthening agent is polyamide epichlorohydrin (PAE). In the addition step, spray coating is applied so that the addition amount of the wet paper strengthening agent is 0.35 to 2.00 wt.%, and the addition amount of the anionic water-soluble polymer is 0.1 to 1.0 wt.% based on absolute dry weight of the pulp fiber of the pulp fiber web, and the spray coating is carried out by placing a nonwoven fabric on a coating wire whose air permeability is 300 to 400 cm3/cm2/sec.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method and apparatus for producing a nonwoven fabric essentially containing pulp fibers, for example, a nonwoven fabric formed only of pulp fibers, or a composite nonwoven fabric comprising pulp fibers and a spunbond nonwoven fabric.

For example, a composite nonwoven fabric composed of a pulp fiber web and a spunbond nonwoven fabric has both liquid absorbency based on the pulp fiber and strength based on the spunbond nonwoven fabric. It is widely used in various applications such as wipers for personal use such as towels.

For example, as disclosed in Patent Document 1, a pulp fiber web and a spunbond nonwoven fabric are laminated and then integrated by a hydroentangling treatment in which a high-pressure water jet is applied. Since the spunbond nonwoven fabric is excellent in strength, it functions as a backing layer for the manufactured composite nonwoven fabric. On the other hand, pulp fiber webs have an excellent liquid absorption function. Therefore, such a composite nonwoven fabric is an excellent composite type that has both the advantages of a pulp fiber web that has good absorbency for both aqueous and oily liquids and the spunbond nonwoven fabric that has excellent strength. It can be provided to the consumer as a nonwoven fabric.

Japanese Patent No. 2533260

Since the composite nonwoven fabric contains a pulp fiber web, it is characterized by excellent liquid absorbency when used. Reducing the amount of paper dust (also called fine fibers, lint, etc.) that falls off from the web is recognized as a problem that should be improved.
With regard to this, conventionally, it is easily conceived to use a wet papermaking method and add a paper strength agent to produce a pulp fiber web. However, as compared with the case of adopting the air-laid method, manufacturing facilities for manufacturing pulp fiber webs by the wet papermaking method are larger, resulting in increased manufacturing costs. Therefore, there is a problem that foreign substances are likely to be mixed in the manufactured composite nonwoven fabric.
In addition, when producing a pulp fiber web containing a paper strength agent by a wet papermaking method, a large amount of the strength agent cannot be fixed to the pulp and flows out into the white water, resulting in a poor yield of the paper strength agent (increased cost). Points are also a problem.
Therefore, it is strongly desired to produce a nonwoven fabric using a pulp fiber web by the air-laid method, but there is a problem that the pulp fibers are likely to come off during processing and use. Addition of chemicals may be considered to deal with this problem, but there is also concern that the chemicals may induce new problems such as contamination of the device, and establishment of an effective technique for coping with this problem is desired.

Accordingly, an object of the present invention is to add an agent for preventing fiber drop-off to an air-laid pulp fiber web, to produce a non-woven fabric that prevents fiber drop-off in both dry and wet conditions, and to prevent stains caused by the added agent. To provide a manufacturing method and a manufacturing apparatus capable of continuous production while suppressing.

The above object is a method for producing a nonwoven fabric essentially containing a pulp fiber web produced by an air-laid method, comprising a hydroentanglement step of hydroentangling the pulp fiber web, and after the hydroentanglement step and an adding step of adding a wet paper strength agent and an anionic water-soluble polymer additive to the pulp fiber web, wherein the wet paper strength agent is polyamide epichlorohydrin (PAE), and the adding step Then, the added amount of the wet paper strength agent is 0.35 to 2.00% by weight with respect to the absolute dry weight of the pulp fibers of the pulp fiber web, and the added amount of the anionic water-soluble polymer is 0.1 to 1.0% by weight, wherein the nonwoven fabric is placed on a coating wire having an air permeability of 300 to 400 cm ³ /cm ² /sec. It can be achieved by a method for producing a nonwoven fabric characterized by:

The anionic water-soluble polymer can be carboxymethylcellulose (CMC) or polyacrylamide (PAM).
The carboxymethyl cellulose preferably has a degree of etherification (DS) of 0.75 or less.

When the two components of the additive are separately spray-coated on the pulp fiber web in the adding step, the additive is applied within 2 seconds after the wet paper strength agent, which is one of the additives, is spray-coated. The other anionic water-soluble polymer may be spray-coated.

The method may further include a cleaning step of cleaning the coating wire.
Further, in the washing step, the coating wire may be washed with a pressure of 1.0 to 5.0 MPa and a water volume of 10 L/min or more.

Furthermore, a composite nonwoven fabric is produced by performing any one of the above nonwoven fabric manufacturing methods on the pulp fiber web produced by the airlaid method placed on the spunbond nonwoven fabric. It is good also as a manufacturing method of.

Further, the above object is provided by an air-laid device for supplying a pulp fiber web, a hydroentangling device for hydroentangling the pulp fiber web, and a hydroentangling device provided downstream of the hydroentangling device for squeezing the pulp fiber web from below. a dewatering device for dewatering; and an adding device provided above the dewatering device for adding a wet paper strength agent and an anionic water-soluble polymer to the pulp fiber web, the dewatering device and the The pulp fiber web is placed and conveyed between an adding device, and the wet paper strength agent and the anionic water-soluble polymer additive are spray-coated onto the pulp fiber web while dehydrating. It can also be achieved by an apparatus for manufacturing nonwoven fabrics, characterized in that it includes an application wire that enables the air permeability of the application wire to be 300 to 400 cm ³ /cm ² /sec.

In addition, a spunbond nonwoven fabric supply device that supplies a spunbond nonwoven fabric, an airlaid device that supplies a pulp fiber web, and the pulp fiber web placed on the spunbond nonwoven fabric are hydroentangled from above to form a composite. A hydroentangling device for forming a type nonwoven fabric, a dewatering device provided downstream of the hydroentangling device for dehydrating the composite nonwoven fabric from below, and the composite nonwoven fabric provided above the dehydration device. and an adding device for adding a wet paper strength agent and an anionic water-soluble polymer to the pulp fiber web of (1), and the pulp fiber web is placed and conveyed between the dewatering device and the adding device and a coating wire that enables the wet paper strength agent and the anionic water-soluble polymer additive to be spray-coated onto the pulp fiber web while dewatering, and the coating wire is ventilated. The object can also be achieved by an apparatus for producing a composite nonwoven fabric characterized by a density of 300 to 400 cm ³ /cm ² /sec.

The apparatus for manufacturing a nonwoven fabric or the apparatus for manufacturing a composite nonwoven fabric may further include a cleaning device for cleaning the coating wire.

According to the present invention, by adding an agent for preventing fiber drop-off to an air-laid pulp fiber web, it is possible to manufacture a nonwoven fabric that prevents fiber drop-off in both dry and wet conditions, and that is continuous while suppressing contamination by the added agent. It is possible to provide a manufacturing method and a manufacturing apparatus capable of practical production.

It is the figure which showed about the suitable apparatus for manufacturing the nonwoven fabric which concerns on this invention.

Hereinafter, the method and apparatus for manufacturing a nonwoven fabric according to the present invention will be described.
The present inventors have confirmed that when a pulp fiber web contains a wet paper strength agent and an anionic water-soluble polymer, fiber shedding (paper dust) can be suppressed. However, it was also confirmed that wet paper strength agents and anionic water-soluble polymer agents contaminate the surroundings during production. Continuous production of nonwovens is also difficult if this contamination is not addressed. Accordingly, the present inventors have also addressed the problem of chemical contamination and have designed suitable conditions and equipment for continuous and efficient production of nonwoven fabrics, and have arrived at the present invention.
The nonwoven fabric containing the pulp fiber web formed by the manufacturing method and apparatus of the present invention can be a nonwoven fabric formed only of the pulp fiber web, or a composite type containing a spunbond nonwoven fabric together with the pulp fiber web. It can also be made into a composite type nonwoven fabric.

Here, a method for producing a nonwoven fabric essentially containing a pulp fiber web produced by an air-laid method includes a hydroentangling step of hydroentangling the pulp fiber web, and a wetting step after the hydroentangling step. and an adding step of adding a paper strength agent and an anionic water-soluble polymer additive to the pulp fiber web, wherein the wet paper strength agent is polyamide epichlorohydrin (PAE), and in the adding step, the The addition amount of the wet paper strength agent is 0.35 to 2.00% by weight, and the addition amount of the anionic water-soluble polymer is 0.1, based on the absolute dry weight of the pulp fibers of the pulp fiber web. ~1.0 wt% by spray coating, wherein the spray coating is carried out by placing the nonwoven fabric on a coating wire having an air permeability of 300 to 400 cm ³ /cm ² /sec. is preferred.
Regarding the addition of the additive as two components of the wet paper strength agent and the anionic water-soluble polymer, the mixed additive obtained by mixing the wet paper strength agent and the anionic water-soluble polymer is added to the pulp fiber. Either the form of spray coating on the web or the form of spray coating the pulp fiber web with the individual additives, which are the wet paper strength agent and the anionic water-soluble polymer, can be adopted.

If the air permeability of the coating wire is less than 300 cm ³ /cm ² /sec, the air permeability becomes too low, and the nonwoven fabric is insufficiently dehydrated before proceeding to the post-process. This is because it accumulates. Conversely, if the air permeability of the coating wire exceeds 400 cm ³ /cm ² /sec, the air permeability will be too high, making it easier for dirt to accumulate in the space inside the coating wire and to contaminate peripheral devices. is deposited.
As can be understood from the above, by using a coating wire having a predetermined air permeability, it is possible to manufacture a nonwoven fabric in which fiber dropout is suppressed in both dry and wet conditions, and to prevent stains caused by added chemicals and to continuously fabricate nonwoven fabrics. production becomes possible.

The anionic water-soluble polymer is preferably carboxymethylcellulose (CMC) or polyacrylamide (PAM).
Further, the carboxymethyl cellulose preferably has a degree of etherification (DS) of 0.75 or less.

When the two components constituting the additive are separately spray-coated onto the pulp fiber web in the adding step, the wet paper strength agent, which is one of the additives, is spray-coated, and the The anionic water-soluble polymer, which is the other additive, may be applied by spraying.

The manufacturing process of the nonwoven fabric may further include a cleaning process for cleaning the coating wire. In the washing step, it is preferable to wash the coating wire with a pressure of 1.0 to 5.0 MPa and a water volume of 10 L/min or more. Pressures below 1.0 MPa are too weak, and pressures above 5.0 MPa can damage the wires in long-term cleaning.

A method for producing a composite nonwoven fabric by performing the above-described method for producing a nonwoven fabric using the pulp fiber web produced by the air-laid method on the pulp fiber web produced by the air-laid method placed on the spunbond nonwoven fabric. can be

The nonwoven fabric and composite nonwoven fabric produced by the present invention contain a wet paper strength agent and an anionic water-soluble polymer on the pulp fiber web side, and are self-crosslinked by the generally known wet paper strength agent. In addition to imparting water resistance to cellulose (pulp fibers) and strengthening hydrogen bonds between cellulose (between pulp fibers) by anionic water-soluble polymers, the wet paper strength agent and anionic water-soluble polymers have a crosslinked structure. It is speculated that by removing the wet paper strength agent, the wet paper strength agent effectively functions (acts), effectively suppressing the falling off of the pulp fibers, and maintaining the water absorption performance.

When carboxymethylcellulose (CMC) is used as the anionic water-soluble polymer, the degree of etherification (DS) of carboxymethylcellulose is preferably set to 0.75 or less. This is because if the degree of etherification exceeds 0.75, the water-solubility is improved, so that it tends to be washed away while being dissolved in water during the dehydration process or the drying process, and the paper dust suppressing effect is likely to be inferior.
It is preferable that the carboxymethyl cellulose has a viscosity of 20 mPa·s or less when adjusted to a 1% aqueous solution. If the viscosity exceeds 20 mPa·s, for example, when spraying with a sprayer, the addition amount cannot be controlled with appropriate pressure and concentration from the nozzle, making it difficult to uniformly apply to the nonwoven fabric. In addition, the highly viscous liquid tends to accumulate during operation, resulting in the problem of sticking stains.

The manufacturing apparatus of the present invention will be further described below with reference to the drawings. Here, as a preferred form of nonwoven fabric, an apparatus for producing a composite nonwoven fabric will be described, which is capable of producing a composite nonwoven fabric by placing a pulp fiber web produced by an air-laid method on a spunbond nonwoven fabric.
A manufacturing apparatus suitable for manufacturing a composite nonwoven fabric will be described with reference to FIG.

A schematic configuration of the composite nonwoven fabric manufacturing apparatus 1 will be described. A manufacturing apparatus 1 shown in FIG. 1 includes an airlaid device 2 for supplying a pulp fiber web, a spunbond nonwoven fabric supply device 3 for supplying a spunbond nonwoven fabric, and a suction device 4 on the upstream side. The suction device 4 is arranged to face the lower side of the air raid device 2 .
Downstream of these devices 2, 3, and 4 in the web transport direction TD are, in order from the upstream side, a hydroentangling device 5 that injects water jets for hydroentangling treatment, and a suction device for dewatering treatment. 6. A drying device 7 is arranged. Downstream of the drying device 7, there is provided a winding device 8 for winding a continuously manufactured composite nonwoven fabric (hereinafter also referred to as composite nonwoven fabric WP).
FIG. 1 illustrates a composite nonwoven fabric manufacturing apparatus in which a spunbond nonwoven fabric supply device 3 is arranged and a composite nonwoven fabric can be manufactured by placing a pulp fiber web manufactured by an air-laid method on a spunbond nonwoven fabric. are doing. If the manufacturing apparatus is changed to one in which a pulp fiber web is supplied directly onto a conveying wire by an air-laid method without using a spunbond nonwoven fabric, it is possible to obtain a nonwoven fabric manufacturing apparatus using only a pulp fiber web.

The air-laid device 2 includes a defibrator 21 that defibrates the sheet-like raw material pulp RP in which the fibers are densely packed into pulp fibers, and an air blower (not shown) that feeds the defibrated pulp fibers PF to an air-laid hopper 23 . and a duct 22 for conveying.

An air raid hopper 23 is arranged downstream of the duct 22 . The air-laid hopper 23 is designed so that the disentangled pulp fibers descend while being dispersed, and are gradually piled up at a stacking position 24 set on the lower surface to form a pulp fiber web PFW.
As described above, the airlaid device 2 is a device and facility capable of supplying a pulp fiber web in a dry process, and the cost of the equipment can be kept lower than that of a device that applies a wet papermaking method and manufactures a pulp fiber web in a wet process. In addition, since the airlaid apparatus 2 is a closed system space from fibrillation to dispersing and dropping of the pulp, contamination of foreign substances is prevented. Contamination can be suppressed to an overwhelmingly low level.

A suction device 4 is arranged below the stacking position 24 so as to face it. More specifically, the suction device 4 has a suction portion 42 on the upper surface of the device main body 41, and the suction portion 42 moves toward the stacking position 24 so as to apply a suction force (negative pressure) to the pulp fiber web PFW. have been set.
Note that FIG. 1 illustrates a case where the pulp fiber web PFW is formed by arranging the air laid hopper 23 and the suction device main body 41 one by one in one stage. However, the arrangement is not limited to this, and the arrangement may be changed so that the air laid hopper 23 and the suction device main body 41 are arranged in two or more stages according to the basis weight (basis weight) and production speed of the pulp fiber web PFW.

A carrier wire 43 for carrying the web is arranged around the suction device 4 . The conveying wire 43 is arranged such that the pulp fiber web PFW on which the pulp fibers PF are piled up at the stacking position 24 can be placed thereon and is conveyed downstream. However, the pulp fiber web PFW is not placed directly on the conveying wire 43 . This will become clear in the description below.
The conveying wire 43 is formed with an open mesh (mesh) so that the suction force of the suction portion 42 extends to the opposite side (upper side).

Below the airlaid device 2 and upstream of the suction device 4, a spunbond nonwoven fabric supply device 3 is arranged. A spunbond nonwoven fabric SW prepared in advance is set in the form of a roll in the spunbond nonwoven fabric supply device 3 . That is, as described above, the designed spunbonded nonwoven fabric SW is taken up during manufacture into a roll, which is pulled out from the spunbonded nonwoven fabric supply device 3, mounted on the above-described carrier wire 43, and transported as described above. It is adapted to be transported to a stacking position 24 .

The aforementioned pulp fiber web PFW is placed on the spunbond nonwoven fabric SW positioned at the stacking position 24 . At the stacking position 24, the suction force of the suction portion 42 of the suction device 4 passes through the conveying wire 43 and acts on the spunbond nonwoven fabric SW and the pulp fiber web PFW thereon. Therefore, a preliminary laminate PWeb (laminated web) in which the spunbond nonwoven fabric SW and the pulp fiber web PFW are laminated is conveyed downstream.
By controlling the supply amount of the pulp fiber web PFW onto the spunbond nonwoven fabric SW when the preliminary laminate PWeb is formed as described above, the pulp fibers contained in the composite nonwoven fabric manufactured by this apparatus are controlled. The web PFW has a basis weight of, for example, 30.0 to 125.0 g/m ² , and is desirably designed so that the ratio of the pulp fiber web is higher than that of conventional general composite nonwoven fabrics. The basis weight of the spunbond nonwoven fabric SW is, for example, 10.0 to 40.0 g/m ² , and the manufactured composite nonwoven fabric (spunbond nonwoven fabric SW + pulp fiber web PFW) is, for example, 40.0 to 165.0 g/m2. ^m2 is preferred. By appropriately adjusting the conveying speed of the pulp fiber web and the amount of supply of the pulp fiber web PFW per hour, etc., and checking the basis weight of the pulp fiber web PFW of the manufactured composite nonwoven fabric, the basis weight is within the desired range. It should be set so that The conveying speed of the pulp fiber web is preferably 150 to 300 m/min, for example.

The above-described preliminary laminate PWeb is suction-compressed by the suction force of the suction device 4, so that the laminated state is maintained. At this time, the fibers of the upper pulp fiber web PFW are in a densified state. However, if the preliminary laminate PWeb is transported into the hydroentangling device 5 on the downstream side as it is, there is a risk that some of the pulp fibers PF will be blown up by water jets (high-pressure water streams).
Therefore, in the present manufacturing apparatus 1, nipping rollers 28 for sandwiching the preliminary laminate PWeb from above and below to stabilize the state of placement of the pulp fiber web PFW on the spunbond nonwoven fabric SW, and upstream of the hydroentangling device 5 A pre-wetting device 30 is provided on the side to apply water to prevent scattering of fibers. The pre-wetting device 30 preferably applies a suction force from a spray nozzle 31 that sprays water mist from above the preliminary laminated body PWeb and from the lower side of the preliminary laminated body PWeb (that is, the lower surface of the pulp fiber web PFW). and a suction device 32 .

Although FIG. 1 illustrates the case where the prewetting device 30 is provided as a new device in front of the hydroentangling device 5 as described above, the present invention is not limited to this. Among a plurality of sets each including a water jet head 51 and a suction device 52 (to be described later) included in the hydroentangling device 5 , the design may be changed such that the head set is used as the prewetting device 30 . In this case, adjustment should be made so that low-pressure water mist is sprayed from the leading water jet head 51 .
In the case of the hydroentangling device 5 in which the number of sets of the water jet head 51 and the suction device 52 sufficient to perform the hydroentanglement treatment is ensured, the top water jet head 51 and the suction device 52 are preliminarily set as described above. Utilizing it as a wet device is effective in suppressing the equipment cost.

Then, in the hydroentangling device 5, a high-pressure water jet is blown onto the preliminarily laminated body PWeb that has been treated by the nipping roller 28 and the prewetting device 30 serving as a pretreatment unit, thereby promoting the entangling of the pulp fibers. This promotes integration of the upper pulp fiber web PFW layer and the lower spunbond nonwoven fabric SW layer (hydroentanglement treatment).
The hydroentangling device 5 exemplarily shown in FIG. 1 has water jet heads 51 arranged in multiple stages (four stages are illustrated in FIG. 1) along the transport direction TD.
Although FIG. 1 does not show the nozzles provided in the water jet head 51 extending in the direction perpendicular to the transport direction TD (web width direction CD), a plurality of nozzles are provided in the width direction. A water jet nozzle is placed at an appropriate position. The hole diameter φ of this water jet nozzle is preferably 0.06 to 0.15 mm. Also, the interval between the water jet nozzles is preferably 0.4 to 1.0 mm.

It is desirable to set the water pressure during the hydroentangling treatment in consideration of the basis weights of the pulp fiber web PFW and the spunbond nonwoven fabric SW. For example, it is preferable to select in the range of 1 to 30 MPa.

A suction device 52 is arranged so as to face the water jet head 51 . While blowing a high-pressure water jet from a water jet head 51 onto the pulp fiber web PFW positioned above, the suction force of a suction device 52 is applied to the lower side of the spunbond nonwoven fabric SW positioned below. Due to the cooperative action of the water jet head 51 and the suction device 52, the pulp fibers on the pulp fiber web PFW side enter the lower spunbond nonwoven fabric SW, or penetrate the spunbond nonwoven fabric SW to reach the opposite side. It is presumed that such a state is formed. Its action promotes the integration of the two layers.

A carrier wire 55 is also arranged in the hydroentangling device 5 . A transport wire 55 receives the preliminary laminate PWeb downstream of the pretreatment stations 28 , 30 and transports it into the hydroentangling device 5 . The carrier wire 55 is arranged to pass between the water jet head 51 of the hydroentangling device 5 and the suction device 52 from the upstream side to the downstream side.
Therefore, the preliminary laminate PWeb conveyed on the conveying wire 55 is subjected to more hydroentangling treatment as it goes downstream in the conveying direction TD, and when it leaves the hydroentangling device 5, the upper pulp fibers Sufficient entangling treatment is realized between the web PFW layer and the lower spunbond nonwoven fabric SW layer.
The composite nonwoven fabric immediately after leaving the hydroentangling device 5 is in a wet state, and the bonds between the pulp fibers are not sufficiently established.

Therefore, as shown in FIG. 1, on the downstream side of the hydroentangling device 5, a dehydration treatment for removing moisture remaining in the pulp fiber web by suction and then a drying treatment are performed to complete the production of the composite nonwoven fabric WP. of suction device 6 and drying device 7 are provided. In this way, when the dehydration treatment and drying treatment are performed by the suction device 6 and the drying device 7 after the production of the composite nonwoven fabric WP, the composite nonwoven fabric can be efficiently produced. A dry composite nonwoven fabric can be produced without applying a large external pressure to the surface.
However, as pointed out above, it is necessary to provide a composite nonwoven fabric that can reliably prevent fine pulp fibers (paper dust) from separating from the pulp fiber web on the composite nonwoven fabric WP. Therefore, the manufacturing apparatus 1 is provided with an adding device 9 for adding a chemical agent for preventing the pulp fibers from coming off.

An adding device 9 for adding a chemical agent is arranged above the suction device 6 with the composite type nonwoven fabric WP being conveyed therebetween. The suction device 6 dehydrates the hydroentangled composite nonwoven fabric from below by, for example, a vacuum system.
More specifically, a coating wire 90 is provided between the suction device 6 on the lower side and the addition device 9 on the upper side in order to uniformly add the chemical agent to the hydroentangled composite nonwoven fabric. be. This coating wire 90 receives the composite nonwoven fabric after hydroentanglement, and during transportation, the composite nonwoven fabric is dehydrated from below and a chemical agent can be added from above. is designed to be in the range of 300 to 400 cm ³ /cm ² /sec as described above. By using such a coating wire 90, it is possible to effectively apply the drug to the composite nonwoven fabric and to efficiently manufacture the composite nonwoven fabric while suppressing contamination of the surroundings.

The adding device 9 adds an additive such as a wet paper strength agent and an anionic water-soluble polymer from the upper side of the composite nonwoven fabric WP after being composited by the hydroentangling device 5, that is, the pulp fiber web PWF (addition process).
The additive composed of two components as described above can be used in both the form of a mixed additive mixed and the form of an individual additive added individually. First, the case of adding the mixed additive will be described. Since the mixed additive is added from the outside to the surface of the pulp fiber web of the composite nonwoven fabric that has been combined, the mixed additive acts efficiently and the pulp fibers are bonded together. serves the function of connecting Since the drying process is performed downstream from the adding device 9, there is no waste such as the added mixed additive being washed away and flowing out.
Further, since the suction device 6 is provided on the lower side, it is advantageous for the mixed additive to permeate into the pulp fiber web, thereby further reliably preventing the pulp fibers from coming off. Addition by spray coating is more advantageous because the mixed additive in the form of a sprayed liquid penetrates into the pulp fiber web. In the adding device 9, the state of the composite nonwoven fabric WP to be manufactured can be checked, and the amount of the mixed additive can be easily controlled.
In addition, the water content of the pulp fiber web PWF portion when the mixed additive is spray-coated by the addition device 9 (the inlet moisture content immediately before entering the addition device 9) is adjusted to 120 to 400%. is preferred. The reason for this is that if the water content is too low, it may not be applied evenly during spray coating, and unevenness may occur. This is because there is a possibility of an increase in the drying load and the occurrence of contamination.

Moreover, it is preferable to perform a dehydration treatment within 10 seconds after the spray coating of the mixed additive. That is, as described with reference to FIG. 1 above, the mixed additive may be dehydrated immediately below the spray coating, or may be dehydrated at a position slightly away from the spray coating (position within 10 seconds of transport time). In short, the optimum time (within 10 seconds after the spray application) can be appropriately determined by checking the permeation and diffusion state of the chemical liquid inside the pulp fiber web PWF when the mixed additive is sprayed.
As the adding device 9, known devices such as spray coating, size press, roll coating, gravure coating, rod bar coating, and air knife coating can be used to add the mixed additive. Although not particularly limited here, spray coating is preferred.

Next, the case where individual additives are used will be described. In the above, the case of adding a mixed additive that is a mixture of a wet paper strength agent and an anionic water-soluble polymer was described, but with an individual additive that separates the wet paper strength agent and an anionic water-soluble polymer, The pulp fiber web PWF may be spray-coated. The adding device 9 in the case of using individual additives as described above is a device equipped with both a first coating device for coating the wet paper strength agent and a second coating device for coating the anionic water-soluble polymer. Can be configured. Here, the first coating device and the second coating device may simultaneously apply the respective agents (wet paper strength agent and anionic water-soluble polymer), or the first coating device and the second coating device may apply the chemicals (wet strength agent and anionic water-soluble polymer) at the same time. 1 and the second coating device may be slightly shifted back and forth for coating.
When applying while shifting back and forth, after spraying one of the individual additives, the wet paper strength agent, within 2 seconds, more preferably within 0.3 seconds to 1.50 seconds, the other individual additive Preferably, some anionic water-soluble polymer is applied by spraying. By optimizing the time until spraying of both, it is possible to expect a technical effect that a crosslinked structure between the wet paper strength agent and the anionic water-soluble polymer can be more effectively constructed.

For each of the wet paper strength agent and the anionic water-soluble polymer in the pulp fiber web PWF, the amount added in terms of solid content is within a predetermined range with respect to the absolute dry weight of the pulp fiber of the pulp fiber web PWF. It is preferable to add as much as possible. Specifically, the amount of the wet paper strength agent added is 0.35 to 2.00% by weight, preferably 0.50 to 1.50% by weight, based on the absolute dry weight of the pulp fiber of the pulp fiber web. do. The amount of the anionic water-soluble polymer added is 0.1 to 1.0% by weight, preferably 0.35 to 0.80% by weight, based on the absolute dry weight of pulp fibers in the pulp fiber web. .
The weight ratio of the anionic water-soluble polymer to the wet paper strength agent, that is, (anionic water-soluble polymer/wet paper strength agent) is preferably 10 to 100% by weight.
If the amount of the wet paper strength agent and anionic water-soluble polymer added is too small, the effect of preventing fiber dropout will decrease, and if it is too large, the effect on the addition rate will level off, whereas it will be excessive. There is concern about the inconvenience that the chemicals will accumulate around the device and make it more dirty.

In the case of spray coating, the concentration of the mixed additive is preferably 0.1 to 2.5%, more preferably 0.7 to 1.5%, and the discharge pressure is preferably 0.1 to 1.5 Mpa. , more preferably 0.3 to 0.8 Mpa. If the pressure is low, the mixed additive will be scattered by the wind caused by the pulp fiber web being conveyed, which may reduce the yield and reduce the effect of removing paper dust. On the other hand, if the pressure is too high, the paper surface of the pulp fiber web that is being conveyed will bounce back, and in this case also, the yield will deteriorate, and the effect of suppressing the falling off of paper dust may decrease.
As the wet paper strength agent, it is preferable to use polyamide epichlorohydrin (PAE), which is known as a wet paper strength agent in the papermaking process, as described above. The solid content concentration of polyamide epichlorohydrin (PAE) of this wet paper strength agent is 10 to 40 wt%, more preferably 20 to 30 wt%. A melamine resin or the like can also be used as a wet paper strength agent.
As the anionic water-soluble polymer, it is preferable to use carboxymethyl cellulose (CMC) or polyacrylamide (PAM) as described above.
By using the above two types in a predetermined ratio, it is possible to suppress clogging of the nozzle of the addition device during production and contamination of peripheral equipment, and to continuously and efficiently produce the composite nonwoven fabric. The manufactured composite nonwoven fabric can be prevented from falling off fibers and have sufficient water absorbency.

As described above, by adding a wet paper strength agent and an anionic water-soluble polymer agent (additive) to a pulp fiber web, it is possible to suppress fiber drop-off of the composite nonwoven fabric produced. As a result, drug contamination spreads to the surroundings. This contamination can be suppressed by adopting the coating wire 90 having a predetermined air permeability as described above.
The manufacturing apparatus 1 shown in FIG. 1 is further provided with a cleaning device 95 for cleaning the coating wire 90 . If a cleaning device is provided, it can be cleaned when the coating wire 90 becomes unacceptably soiled.
The cleaning device 95 exemplified in FIG. The washing device 95 includes a shower nozzle 97 for injecting washing water, and a suction device 99 for sucking the washing water, which is arranged to face the shower nozzle 97 with the coating wire 90 therebetween. be.

The type of the shower nozzle 97 to be adopted is not limited, and for example, a needle type or a fan type can be adopted. Further, if a sliding device is added to the shower nozzle 97 so that it reciprocates within a predetermined range, the cleaning power for the coating wire 90 can be improved.

A preferred configuration of the coating wire 90 described above will be described in detail below.
The coating wire 90 can be made of a plastic material, such as polyester or polyamide. Polyester is characterized by high strength and low elongation, so the coating wire 90 is made of polyester. preferably.
The air permeability of the coating wire 90 can be defined by the woven structure, the number of threads, and the wire diameter. Specifically, for example, when the number of heavy weaves is increased, when the number of stitches per unit area is increased, or when the wire diameter is increased, the air permeability decreases.

Dehydration through the coating wire 90 is carried out by the wire opening space and the void space. The field is mainly performed by the void space. This is because the dehydration force acts directly on the nonwoven fabric in the case of a single weave with openings, but in the case of a multiple weave such as a double weave, the direction of the water changes when it passes through the wire, reducing the dewatering speed. It is possible to suppress the action of excessive dehydration force on the nonwoven fabric.
As described above, the coating wire 90 used in ^the manufacturing apparatus 1 is designed to have air permeability by adjusting the number of weaves, the number of ^stitches , and the wire diameter. By doing so, it is possible to efficiently apply the chemical while suppressing contamination to the surroundings.
The air permeability of the wire described above is the amount of air of 1 atm passing through the wire in a unit time, and can be measured according to JIS L1096 8.26.1A (Frazier method). The larger the air permeability number, the higher the air permeability and the easier the dehydration.

In FIG. 1, a drying device 7 is further installed downstream of the suction device 6 and the adding device 9, and the composite nonwoven fabric WP comprising the pulp fiber web PWF spray-coated with the additive is dried. The drying device 7 here preferably employs a non-compression type dryer, preferably an air-through dryer. In FIG. 1, a rotatable dryer body 71 of the air-through dryer is a cylindrical body, and has a large number of through-holes on its peripheral surface. It is preferable to adopt a configuration in which the air is sucked in toward the side.
The composite nonwoven fabric WP, which is continuously produced while suppressing contamination of equipment around the addition device in this way, is wound around the roll 81 of the winding device 8 after drying.
As described above, the composite nonwoven fabric manufactured by the manufacturing apparatus 1 according to the present invention is such that the pulp fibers are suppressed from coming off.

(Example)
Examples and comparative examples in which composite nonwoven fabrics including spunbonded nonwoven fabrics are manufactured by carrying out the manufacturing method using the manufacturing apparatus according to the present invention will be described below.
Polyamide epichlorohydrin (PAE) as a wet paper strength agent and boxymethyl cellulose (CMC) or polyacrylamide (PAM) as an anionic water-soluble polymer added to the pulp fiber web of the composite nonwoven fabric. For the composite nonwoven fabrics of Examples 1 to 8 when the additive amounts and mixing ratios were as shown in Table 1, and for Comparative Examples 1 to 7 where the addition amount and mixing ratio were as shown in Table 2, the shedding paper during drying The amount of powder, the amount of paper dust removed after wiping in a dry state, the amount of paper dust removed after wiping in a wet state, the contamination of the entire device, and the wire contamination were checked and comprehensively evaluated.
In this example, the wet paper strength agent and the anionic water-soluble polymer are separately sprayed by the addition device as individual additives. showing. Then, the ejection pressure, drug concentration, nozzle arrangement, and space between the spray (1) and the spray (2) by each of the first coating device (spray (1)) and the second coating device (spray (2)) time (sec) is also shown.

1) Amount of paper dust falling off during drying (visual observation)
When the nonwoven fabric was shaken ten times over black paper in a dry state, the amount of paper dust that fell off was visually evaluated.
The amount of residual paper dust is small and good (excellent ◎)
The amount of residual paper dust is inferior to the excellent state, but it is generally at a usable level (Possible 〇)
The amount of residual paper dust is conspicuous and it is not suitable to use (impossible x)
2) Amount of paper dust after wiping (visual observation)
The generation of paper dust in dry and wet conditions was evaluated by 10 monitors.
The amount of residual paper dust is small and good (excellent ◎)
The amount of residual paper dust is inferior to the excellent state, and it is at the level where some users judge that it cannot be used (Possible 〇)
The amount of residual paper dust is conspicuous and it is not suitable to use (impossible x)

3) Conditions during operation (visual observation)
At the time of collecting the level of each example and comparative example, the degree of contamination of the equipment was visually evaluated.
The level of contamination of the equipment is within the range of normal operation (excellent ◎)
The level of dirt on the device is inferior to normal (Possible 〇)
Level at which it is difficult to continue operation due to significant contamination of equipment (impossible x)

4) Contamination of coating wire (visual observation)
When the standards of each example and comparative example were collected, the state of contamination of the coating wire was visually evaluated.
Dirt on the coating wire is good at the same level as when the anionic polymer is not added (excellent ◎)
Continuous operation is possible even though the coating wire becomes dirty (○)
Excessive contamination of the coating wire (impossible x)

5) Comprehensive Evaluation All evaluation items were scored based on the following items. The comprehensive evaluation was 3 or more, and the quality of the material was good and the continuous operation was possible.
The condition of equipment contamination is ×, and there is difficulty in manufacturing nonwoven fabric (1 point)
There is an X item for improvement of paper dust, but the operation status is 〇 or higher (2 points)
All evaluations are 〇 or higher, and there are 2 ◎ (3 points)
All evaluations are 〇 or higher, and there are 3 ◎ (3.5 points)
All evaluations are 0 or higher, and there are 4 ◎ (4 points)
All evaluations are ◎ (5 points)

As shown in Table 1 above, in Examples 1 to 8, the added amount of the wet paper strength agent was 0.35 to 2.00 weight, and the added amount of the anionic water-soluble polymer was 0.1 to 1.0. The nonwoven fabric is manufactured in such a manner that the content is 10% by weight, whereby the amount of paper dust is suppressed in the composite nonwoven fabric after wiping in both dry and wet conditions. In addition, there are no problems such as contamination of the periphery of the device or coating wire, which hinders manufacturing, and the overall evaluation is 3 points or more.
In Example 1, the application interval between spray (1) and spray (2) was slightly long, so the amount of dewatering was large, and the effect of suppressing paper dust was slightly reduced, but there was no problem, and there was no problem in the manufacturing process. .
In Example 2, there is almost no contamination of the device and the nozzle, it is suitable for continuous production, and paper dust is suppressed in the obtained nonwoven fabric. All evaluations are ⊚ and are in the best mode.
In Example 3, since the amount of water used in the shower for washing the coating wire is slightly small, the wire is slightly soiled, but there is no problem in the manufacturing process.
In Example 4, since the pressure of the shower for cleaning the coating wire is slightly weak, the wire is slightly soiled, but there is no problem in the manufacturing process.
In Example 5, the amount of water used to wash the coating wire was less than the necessary amount, so the wire was slightly soiled, but there was no problem with the manufacturing process.
In Example 6, the application interval between the spray (1) and the spray (2) is slightly short, so the effect of suppressing paper dust is slightly reduced, but there is no problem, and there is no problem in the manufacturing process.
In Example 7, since polyacrylamide (PAM) was used as the anionic water-soluble polymer, the effect of suppressing paper dust was reduced, but there was no problem, and there was no problem in the manufacturing process.
In Example 8, the degree of CMC etherification is high, so the effect of suppressing paper dust is low, but there is no problem, and there is no problem in the manufacturing process.
In addition, it can be confirmed from Examples 1 and 6 to 8 that the shower treatment for cleaning the coating wire is not essential, and it can be seen that it is not necessary to provide a cleaning device for cleaning the coating wire if the conditions are met. .

On the other hand, in Comparative Examples 1 to 5, the addition amount of the wet paper strength agent is outside the range of 0.35 to 2.00% by weight, or the addition amount of the anionic water-soluble polymer is 0.1 to 1.0%. Either it is out of the 0% by weight range. If a nonwoven fabric is produced under such conditions, a nonwoven fabric with insufficient paper dust suppression will be produced (evaluated as ×). Also, in Comparative Examples 6 and 7, the air permeability of the coating wire is outside the range of 300 to 400 cm ³ /cm ² /sec. When such a wire for application is used, contamination of the apparatus and contamination of the wire become obstacles, making it difficult to continuously produce the nonwoven fabric (evaluated as ×).

The above-described examples describe the case of producing a composite nonwoven fabric from a pulp fiber web and a spunbond nonwoven fabric by adding a predetermined amount of a wet paper strength agent and an anionic water-soluble polymer. It is needless to say that the same effect as described above can be expected even when producing a nonwoven fabric with.
Although the description of the embodiments is finished above, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

1 Composite type nonwoven fabric manufacturing device 2 Airlaid device 3 Spunbond nonwoven fabric supply device 4 Suction device 5 Hydroentangling device 6 Suction device 7 Drying device 8 Winding device 9 Adding device 21 Defibering machine 22 Duct 23 Airlaid hopper 24 Stacking position 28 Pinch roller 30 Pre-wet device 31 Spray nozzle 32 Suction device 41 Suction device main body 42 Suction part 43 Transfer wire 51 Water jet head 52 Suction device 55 Transfer wire 90 Application wire 95 Cleaning device 97 Shower nozzle 99 Suction device SW Spunbond nonwoven fabric PF Pulp fiber PFW Pulp fiber web PWeb Preliminary laminate (laminated web)
WP Composite type nonwoven fabric TD Conveying direction

Claims (10)

A method for producing a nonwoven fabric essentially containing a pulp fiber web produced by an air-laid method,
a hydroentangling step of hydroentangling the pulp fiber web;
and an adding step of adding a wet paper strength agent and an anionic water-soluble polymer additive to the pulp fiber web after the hydroentangling step, wherein the wet paper strength agent is polyamide epichlorohydrin (PAE). and
In the adding step, the addition amount of the wet paper strength agent is 0.35 to 2.00% by weight with respect to the absolute dry weight of the pulp fiber of the pulp fiber web, and the anionic water-soluble polymer It is sprayed so that the amount added is 0.1 to 1.0% by weight,
A method for producing a nonwoven fabric, wherein the spray coating is performed by placing the nonwoven fabric on a coating wire having an air permeability of 300 to 400 cm ³ /cm ² /sec. The method for producing a nonwoven fabric according to claim 1, wherein the anionic water-soluble polymer is carboxymethylcellulose (CMC) or polyacrylamide (PAM). 3. The method for producing a nonwoven fabric according to claim 2, wherein the carboxymethyl cellulose has a degree of etherification (DS) of 0.75 or less. When the two components of the additive are separately spray-coated on the pulp fiber web in the adding step, the additive is applied within 2 seconds after the wet paper strength agent, which is one of the additives, is spray-coated. 4. The method for producing a nonwoven fabric according to any one of claims 1 to 3, wherein the anionic water-soluble polymer, which is the other of the two, is spray-coated. 5. The method for manufacturing a nonwoven fabric according to any one of claims 1 to 4, further comprising a cleaning step of cleaning said coating wire. 6. The method for producing a nonwoven fabric according to claim 5, wherein in the washing step, the coating wire is washed with a pressure of 1.0 to 5.0 MPa and a water volume of 10 L/min or more. The method for producing a nonwoven fabric according to any one of claims 1 to 6 is performed on the pulp fiber web produced by the air-laid method placed on the spunbond nonwoven fabric to produce a composite nonwoven fabric. A method for producing a composite nonwoven fabric. an airlaid device for supplying a pulp fiber web;
a hydroentangling device for hydroentangling the pulp fiber web;
A dewatering device provided downstream of the hydroentangling device for dewatering the pulp fiber web from below; The pulp fiber web is placed and conveyed between the dewatering device and the adding device, and the wet paper strength agent and the anionic system are dehydrated while dewatering. an applicator wire enabling the additive with a water-soluble polymer to be spray applied to the pulp fiber web;
An apparatus for producing a nonwoven fabric, wherein the coating wire has an air permeability of 300 to 400 cm ³ /cm ² /sec. a spunbond nonwoven fabric supply device for supplying a spunbond nonwoven fabric;
an airlaid device for supplying a pulp fiber web;
a hydroentangling device for forming a composite nonwoven fabric by hydroentangling the pulp fiber web placed on the spunbond nonwoven fabric from above;
A dewatering device provided downstream of the hydroentangling device for dewatering the composite nonwoven fabric from below, and a wet paper strength agent for the pulp fiber web of the composite nonwoven fabric provided above the dewatering device. and an adding device for adding an anionic water-soluble polymer, and the pulp fiber web is placed and conveyed between the dewatering device and the adding device, and the wet paper strength is obtained while dewatering an application wire enabling the agent and the anionic water-soluble polymer additive to be spray-applied to the pulp fiber web;
An apparatus for producing a composite nonwoven fabric, wherein the coating wire has an air permeability of 300 to 400 cm ³ /cm ² /sec. The nonwoven fabric manufacturing apparatus according to claim 8 or the composite nonwoven fabric manufacturing apparatus according to claim 9, further comprising a cleaning device for cleaning the coating wire.

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