JP2018188747A - Nonwoven fabric wiper and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel nonwoven fabric wiper excellent in water retention and bulky feeling.SOLUTION: The nonwoven fabric wiper 1 comprises a plurality of substrate sheets 10, 20 in which thermofusible cellulosic fiber webs 12, 22 including cellulosic fibers and thermofusible fibers and synthetic fiber-based webs 14, 24 comprising synthetic fibers are laminated and subjected to a hydroentanglement treatment. The substrate sheets are laminated and mutually joined via joint parts 30 in which the thermofusible fibers are molten and solidified.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nonwoven fabric wiper having a novel structure formed by superposing base sheets formed of natural cellulose fibers or regenerated cellulose fibers (hereinafter referred to as cellulosic fibers) and synthetic fibers.

  A composite nonwoven fabric wiper formed of cellulosic fibers and synthetic fibers such as polypropylene is obtained by laminating a cellulosic fiber web and a synthetic fiber web and then hydroentangling it. Such a non-woven wiper is an excellent non-woven product having both strength and water retention, and thus is used in various applications as an industrial wiper and a personal wiper.

  Regarding the above-described composite type nonwoven fabric wiper, for example, a basic manufacturing process is disclosed in Patent Document 1, and a desired nonwoven fabric is prepared by appropriately adjusting the ratio and basis weight of the cellulosic fiber web and the synthetic fiber web. A wiper can be manufactured.

Japanese Patent No. 2533260

If the water retention of the nonwoven fabric wiper can be improved, it can be provided to the user as a nonwoven fabric wiper with high water absorption capability. Here, conventionally, as a countermeasure for improving the water retention in the nonwoven fabric, the basis weight of the web is generally increased.
However, if the basis weight of the web is increased and the hydroentanglement process described above is performed, the density at which the fibers are entangled also increases. As a result, the finished non-woven fabric has a tendency to be a non-woven fabric having a reduced thickness, poor bulkiness (bulk feeling), and poor texture.

  Therefore, the main object of the present invention is to provide a novel nonwoven wiper excellent in water retention and bulkiness. Moreover, it is providing the manufacturing method of this nonwoven fabric wiper.

  The object is to provide a base sheet in which a heat-fusible cellulose fiber web in which heat-fusible fibers are blended with cellulosic fibers and a synthetic fiber web made of synthetic fibers are laminated and hydroentangled. It can be achieved by a non-woven wiper characterized in that it includes a plurality, the base sheet is superposed, and the base sheets are joined via a joint where the heat-fusible fibers are melted and solidified.

And, in the width direction perpendicular to the conveying direction at the time of manufacturing the nonwoven fabric wiper, the arrangement of the joint portion is designed so that there is no full-width non-joint portion other than the joint portion. Something is desirable.
And it is preferable that the arrangement | positioning area ratio of the said junction part is the range of 4-25%.

Further, it is preferable that two base sheets are included and the synthetic fiber webs are overlapped with each other facing each other.
Moreover, it is good also as what includes the said base material sheet in multiple numbers and the said heat-fusible cellulosic fiber web is piled up in the form used as front and back.
And what the basic weight of the said base material sheet is 40-90 g / m < ² > can be employ | adopted suitably.

  The object is to provide a base sheet in which a heat-fusible cellulose fiber web in which heat-fusible fibers are blended with cellulosic fibers and a synthetic fiber web made of synthetic fibers are laminated and hydroentangled. A plurality of the prepared base materials are individually fed out, and then the base material sheets are overlapped with each other to obtain a preliminary laminate, and a predetermined arrangement while sandwiching the preliminary laminate A fixing process step of bonding and fixing the base sheets together by a bonding part in which at least a part of the heat-fusible fiber is melted and solidified by performing a partial heat treatment at an area ratio. It is also achieved by the manufacturing method of the characteristic nonwoven fabric wiper.

And it may manufacture by superposing | stacking in the form which manufactured the said base material sheet | seat, and the said synthetic fiber type | system | group webs faced each other.
Moreover, you may manufacture by superimposing in the form which contains the said base material sheet in multiple numbers and the said heat-fusible cellulose fiber web becomes a front and back.

  A heater device or an ultrasonic device can be employed as a heating means for performing the heat treatment.

  The nonwoven fabric wiper according to the present invention is formed of a composite nonwoven fabric having both strength and water retention as a base sheet, and is formed into a new structure by superimposing it, so that it is excellent in both bulkiness and water retention. It can be provided as a functional non-woven wiper.

It is the expanded schematic diagram shown about the nonwoven fabric wiper which concerns on this invention, Fig.1 (a) is a top view, FIG.1 (b) is a YY arrow sectional drawing in (a). It is the figure shown about the surface state of the nonwoven fabric wiper which concerns on this invention, and several examples. It is the schematic of the process shown in order to demonstrate the manufacturing process of the nonwoven fabric wiper which concerns on this invention.

Hereinafter, the nonwoven fabric wiper which concerns on one Embodiment of this invention is demonstrated with reference to figures.
FIG. 1 is a schematic view showing a part of the nonwoven fabric wiper 1 of the present invention in an enlarged manner, FIG. 1 (a) is a plan view, and FIG. 1 (b) is a cross-sectional view taken along line YY in FIG. It is.
The outline of the nonwoven fabric wiper 1 will be described in advance. A composite nonwoven fabric having a normal function (a nonwoven fabric made of a cellulosic fiber web and a synthetic fiber web) is used as a base sheet, and the base sheet is overlapped. A new structure is formed. In order to realize this novel structure, a heat-fusible cellulosic fiber web in which heat-fusible fibers are blended with cellulosic fibers is employed. Thereby, the base material sheets arranged adjacent to each other are fixed to each other by a joint portion formed by melting and solidifying the blended heat-fusible fiber, and the laminated nonwoven fabric wiper 1 is laminated (laminated structure). Is obtained.

In addition, the present inventor causes the problem pointed out earlier by simply increasing the basis weight of a single nonwoven fabric, but when the same basis weight is obtained by overlapping a plurality of nonwoven fabrics having a small basis weight, water retention is improved, After confirming that the decrease in thickness (decrease in bulkiness) could be suppressed, the point of interest of the present invention was obtained. However, in the case of hydroentanglement, unlike ordinary paper, since the cellulose fibers do not have a closely overlapping structure, the fibers in the bonded portion are easily removed, and it is difficult to bond the cellulose fibers. In this regard, by adopting a configuration in which a heat-fusible fiber is blended with a cellulosic fiber, the problem has been solved and the present invention has been completed.
Hereinafter, the nonwoven fabric wiper 1 will be described in more detail based on the drawings.

  Referring to FIG. 1 (b), the nonwoven fabric wiper 1 is formed by overlapping a first base sheet 10 and a second base sheet 20. Here, each of the 1st base material sheet 10 and the 2nd base material sheet 20 is the composite type nonwoven fabric by the heat-fusible cellulose fiber webs 12 and 22 and the synthetic fiber webs 14 and 24 similarly. is there. A composite nonwoven fabric made of cellulosic fibers and synthetic fibers has the advantage of having both strength and water retention. And as above-mentioned, it has a joining (adhesion) function by mix | blending a heat-fusible fiber with a cellulosic fiber.

The said base material sheets 10 and 20 are manufactured by the conventionally well-known water flow entanglement process which entangles fibers by injecting a water flow on the laminated | stacked web. In general, the hydroentanglement process is performed by placing a cellulosic fiber web on a synthetic fiber web and jetting a water flow of a predetermined pressure from above. As a result, a state (entanglement) in which the cellulosic fibers enter the synthetic fiber web and the fibers are entangled with each other is formed, and an integrally laminated nonwoven fabric is obtained.
In the nonwoven fabric produced as described above, a part of the cellulosic fibers penetrates the lower synthetic fiber web by the hydroentanglement treatment, and there are a large number on the back surface of the nonwoven fabric (that is, the surface of the synthetic fiber web). It is in a state.

On the other hand, the non-woven wiper 1 of the present invention obtained by superimposing the base sheets 10 and 20 is water retaining as long as the hydrophilic cellulosic fiber web side is located on both surface sides without distinction between the front and back sides. A wiper with excellent properties can be obtained.
Accordingly, in FIG. 1B, the base fiber sheets 10 and 20 are arranged so that the synthetic fiber webs 14 and 24 sides of the base sheet 10 and 20 face each other (that is, the cellulosic fiber webs 12 and 22 are located on the surface side). And the nonwoven fabric 1 is designed.
However, as described above, the cellulosic fiber webs 12 and 22 in which the heat-fusible fibers are blended penetrate to the opposite side, and are present on the synthetic fiber webs 14 and 24 on the opposite side. Therefore, in FIG. 1 (b), a part of the heat-fusible cellulosic fiber web that penetrates and appears on the opposite side is indicated by reference numerals 12a and 22a.

  As what constitutes a cellulosic fiber, the thing based on natural fibers, such as a pulp and cotton, is employable. For example, when wood pulp is employed, NBKP such as radiata pine, slash pine, southern pine, spruce, and Douglas fir is preferable, and may be appropriately selected in consideration of defibration properties, yield, and the like. Rayon or the like can be preferably used as the regenerated cellulose fiber.

And as a heat-fusible fiber mix | blended with a cellulosic fiber, it is what employ | adopts what has a melting point lower than the synthetic fiber which comprises the said synthetic fiber type web, and can join cellulosic fibers when it melts and solidifies. preferable. For example, a composite type formed in a so-called core-sheath structure in which a first synthetic resin having a relatively high melting point is disposed on the center side and a second synthetic resin having a melting point lower than that of the first synthetic resin is disposed on the outer side. The heat-fusible fiber can be used.
Examples of the first synthetic resin include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6, nylon 6 and 6, polymethylpentene, polypropylene, ethylene-propylene copolymer, ethylene vinyl alcohol copolymer Thermoplastic resins such as homopolymers of polyolefins such as coalescence, copolymers, graft-modified products, or polymer alloys thereof can be used.
And as the second synthetic resin, for example, a propylene copolymer such as polyethylene, ethylene-propylene copolymer, ethylene-butene-1-propylene terpolymer, ethylene-vinyl acetate copolymer, A thermoplastic resin such as ethylene-methyl acrylate copolymer can be used.

  The synthetic fiber constituting the synthetic fiber web is preferably selected from nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, polystyrene and the like.

In addition, it is preferable that the basic weight of the said base material sheets 10 and 20 shall be 40-90 g / m < ² >. For example, if the basis weight of each of the base material sheets 10 and 20 is 40 g / m ² , the basis weight of the nonwoven fabric wiper 1 is doubled to 80 g / m ² . As shown in the examples described later, the nonwoven fabric wiper 1 of the present invention is superior in water retention and bulkiness compared to a single nonwoven fabric wiper having a basis weight of 80 g / m ² .

  When the base sheet 10 or 20 is heated by a heating means (not shown), the base sheet 10 and 20 are fixed to each other by a joint portion 30 formed by melting and solidifying the heat-fusible fiber at a plurality of locations. The joining part 30 may be one in which, in addition to the joining of the synthetic fibers, the joining of the synthetic fibers and the cellulose fibers, or the joining of the cellulose fibers is realized along with the melting of the heat-fusible fibers. FIG.1 (b) has expanded and shown the mode of such a cross section.

In the nonwoven fabric wiper 1, as described above, the joint portion 30 is a portion that functions to fix the base sheet 10 and the base sheet 20, and the wiper is a portion that has low water retention. On the other hand, if the ratio of the joint portions 30 per area is too low, the base sheet 10 and the base sheet 20 are easily separated, and the outer shape of the laminated nonwoven fabric wiper 1 may not be maintained.
Therefore, it is preferable that the arrangement area ratio (the ratio of the junction area per unit area) of the junction 30 is 4 to 25%. When the arrangement area ratio is less than 4%, the bonding between the base sheet 10 and the base sheet 20 becomes unstable. Moreover, when the arrangement area ratio exceeds 25%, there is a concern that the wiping ability as a wiper is lowered.

When forming the joint portion 30, for example, by using a heating roller device having a plurality of convex portions on the peripheral surface and heating the substrate sheets 10 and 20 in an overlapped state between the rollers, The melted and solidified portion is formed as the joint portion 30. Since the joints 30 formed in this way are significantly reduced in thickness, they appear as a plurality of recesses 35 on the wiper surface corresponding to each joint 30 (see FIG. 1B).
Thus, the state of the wiper surface in which a plurality of recesses 35 are present has the same form as when embossing is performed. It has been known that the embossed wiper has improved dirt removal performance. Therefore, the nonwoven fabric wiper 1 of the present invention is a nonwoven fabric wiper with improved scraping performance.

With regard to the arrangement of the joint portions 30, a nonwoven fabric wiper can be designed by appropriately adjusting the shape of one joint portion 30 and the arrangement thereof, and this will appear as a recess 35 on the surface of the nonwoven fabric wiper. FIG. 2 shows several examples of the state of the surface of the non-woven wiper.
FIG. 2A shows a case where one of the concave portions 35 (joint portion 30) is a square-shaped dod and is arranged evenly and formed into a dot pattern. Similarly, FIG. ) Is a case where a cross shape is adopted, and (d) is a case where a “<” shape is adopted.
In any case of FIG. 2, as described above, the arrangement area ratio of the joint portion 30 is preferably set to be in the range of 4 to 25%.

In the case of FIG. 2A, when one dod is 1 mm × 1 mm and the pattern is 5 mm in pitch, the arrangement area ratio is 4%. Similarly, when the dod is 1 mm × 1 mm and the pitch is 3.16 mm, the arrangement area ratio is 10%. If the dod is 1 mm × 1 mm and the pitch is 2.00 mm, the arrangement area ratio is 25%.
Further, when the dod is 1.3 mm × 1.3 mm and the pitch is 6.5 mm, the arrangement area ratio is 4%. When the pitch is 4.11 mm as the same dot, the arrangement area ratio is 10%. Furthermore, when the pitch is 2.60 mm as the same dot, the arrangement area ratio is 26%.

In the case of FIG. 2 (b), when the band shape is 1 mm × 30 mm, the pitch in the conveyance direction MD of the nonwoven fabric is 10 mm, and the pitch in the width direction CD perpendicular to the conveyance direction MD is 20 mm, the arrangement area ratio is 4. 3%. When the pitch in the width direction CD is narrowed to 15 mm, the arrangement area ratio is 5.7%.
In the case of FIG. 2C, if the cross-shaped dod is 1 mm wide × 3 mm long and the pitch is 9 mm, the arrangement area ratio is 14.8%.
In the case of FIG. 2D, if the short side is 1 mm, the long side is 2 mm, and a "<"-shaped dod is used, and the pitch is 16 mm, the arrangement area ratio is 4.7%.

With respect to the arrangement of the recesses 35 (joint portions 30) shown in FIG. 2, there are preferable conditions when considering smooth production in the production process.
In FIG. 2, the direction perpendicular to the web conveyance direction MD is the width direction CD. Any of the nonwoven fabric wipers 1 is desirably designed so that at least one, preferably a plurality, of the concave portions 35 (joint portions 30) exist in the width direction CD. In other words, it is desirable to design so that a portion (referred to as a non-joined portion) other than the concave portion 35 (joined portion 30) does not exist in the entire width of the nonwoven fabric wiper 1 in the width direction CD.
The above conditions are to realize smooth web conveyance when forming the joint 30 in the manufacturing process. For example, it is assumed that a convex portion is arranged on one peripheral surface of a roller pair in the heating roller device, and the joining portion 30 is provided on the web based on the convex portion. Here, if there is a flat region portion (that is, a non-joined portion where no convex portion exists) on the circumferential surface of the roller regularly in the circumferential direction, the roller will rattle when it rotates, This hinders smooth web transport. In order to prevent this, it is necessary to design the roller so that the convex portion always exists when viewed in the width direction. And the nonwoven fabric wiper 1 manufactured using the roller apparatus which satisfy | fills such conditions has the structural characteristic that a non-joining part does not exist in the full width of the width direction CD. .
Therefore, in the nonwoven fabric wiper 1, as in the example shown in FIG. 2, the pattern is designed so that a plurality of recesses 35 (joint portions 30) are always present in the width direction CD, and preferably a plurality of recesses 35 are present. .

FIG. 3 is a view schematically showing an outline of the manufacturing process of the nonwoven fabric wiper 1.
On the left side of FIG. 3, two base material sheets 10 and 20 wound in a roll shape are prepared in advance. Each base sheet 10 and 20 is obtained by laminating a heat-fusible cellulosic fiber web in which a heat-fusible fiber is blended with a cellulosic fiber and a synthetic fiber web composed of synthetic fibers, and laminating it. It is what was done.
In addition, when manufacturing the said base material sheets 10 and 20, although a cellulosic fiber web may be manufactured by the process by any of a wet system and a dry system, a heat-fusible fiber is added to a cellulosic fiber. From the viewpoint of producing a heat-fusible cellulosic fiber web that is uniformly blended, it is preferably produced by a dry method.

  In FIG. 3, the upper base sheet 20 is a non-woven fabric in which a heat-fusible cellulose fiber web 22 is located on the upper surface side, and the lower base sheet 10 is a heat-fusible cellulose fiber on the lower surface side. It is a nonwoven fabric in which the web 12 is located. The base sheets 10 and 20 are set so that the synthetic fiber webs 14 and 24 face each other. However, as described above, the surfaces of the synthetic fiber-based webs 14 and 24 are in a state where portions 12a and 22a of the heat-fusible cellulosic fiber web penetrating from the opposite side are present. .

The base material sheets 10 and 20 sent out from the roll first undergo a lamination forming step. In this step, the base sheets 10 and 20 are guided together between the sandwiching roller devices 2 to form a preliminary laminate 40 in which the base sheets are stacked.
Downstream of that, a fixing process step is performed in which a partial heat treatment is performed at a predetermined arrangement area ratio while sandwiching the preliminary laminate 40.
Here, heating means 3 for performing partial heat treatment on the preliminary laminate 40 is provided. The heating means 3 performs a partial heat treatment at a predetermined arrangement area ratio to melt at least a part of the heat-fusible fiber. As the heating means 3, a heater device that includes a heat generating portion and performs a partial heating process while sandwiching the preliminary laminate 40, an ultrasonic device that melts a heat-fusible fiber using ultrasonic waves, and the like, A known heating device can be appropriately employed. Therefore, after passing through the fixing treatment step, it is possible to obtain the nonwoven fabric wiper 1 in which the base sheet is bonded to each other by the bonding portion 30 in which at least a part of the heat-fusible fiber is melted and solidified.

FIG. 3 illustrates the case of a non-woven wiper manufactured by two base sheet (2PLY). In the case of more than this, for example, three base sheet (3PLY), one roll of base sheet may be added and three sheets may be overlapped and manufactured in the same manner.
In this case, it is preferable to design so that the heat-fusible cellulosic fiber web is located on both the front and back surfaces of the produced nonwoven wiper. A hydrophilic heat-fusible cellulosic fiber web can be arranged on the front side to make a nonwoven wiper with high water retention. Thereby, even if it uses without being conscious of the front and back, it can provide to a user as a wiper with high water absorption capability.

(Example)
Hereinafter, examples of the nonwoven fabric wiper according to the present invention will be described. Example 1 is a nonwoven fabric wiper 1A in which two base sheets having a basis weight of 62 g / m ² are overlaid (2PLY), and Example 2 is in which ^two base sheets having a basis weight of 62 g / m ² are overlaid (2PLY). Non-woven wiper 1B, Example 3 is a non-woven wiper 1C in which three base sheets having a basis weight of 58 g / m ² are overlaid (3 PLY), and Comparative Example 1 is a simple substance having a basis weight of 123.7 g / m ² (1 PLY ) Non-woven wiper 100.

About each nonwoven fabric wiper, basic weight, thickness, specific volume, intensity, texture, and water retention were evaluated and comprehensively judged.
Basis weight: Measured according to the method defined in JIS P8124.
Thickness: Measured under a weight of 37.85 g / cm ² using a thick peacock paper.
Specific volume: It calculated | required by thickness (mm) x1000 / basis weight (g / m < ² >).
The specific volume is a numerical value reflecting the bulkiness (bulk feeling), and those less than 60 mm ² are marked as x due to insufficient bulkiness.
Strength: The tensile strength in the vertical and horizontal directions at the time of drying was measured with a test piece width of 25 mm in accordance with JIS P8113. The vertical direction corresponds to the web conveyance direction, and the horizontal direction corresponds to the width direction.
Texture: According to sensory evaluation by 10 monitors, ○: good, Δ: normal, ×: bad.
Water retention: The obtained nonwoven sheet was cut into 76 × 76 mm square test pieces, and the dry weight (W ₁ ) was measured. Then, after immersing this test piece in distilled water for 2 minutes, one corner of the test piece is made to be an upper apex, and the apex and two adjacent corners are supported and extended ( 100% RH), and the weight (W ₂ ) after standing for 30 minutes was measured.
A value of (W ₂ −W ₁ ) was calculated, and this value was converted into a water retention amount (g) per unit area (1 m ² ) and a water retention amount (g) per unit weight (g). Both conversion values indicate that the larger the value, the better the water retention. For the unit area, 500 g / m ² or more was ○, and less than X was X. Moreover, about unit weight, 400g / g or more was set to (circle) and less than it was set to X.
Comprehensive judgment: The data of each non-woven wiper in which the case of ○ was excellent and the case of containing x was not possible is as shown in Table 1 below.

From the above, it can be seen that according to the present invention, it is possible to provide a non-woven wiper having a novel structure that is excellent in water retention, bulkiness, and texture while having a predetermined strength.
The nonwoven fabric wiper according to Comparative Example 1 (single nonwoven fabric wiper with increased basis weight) was significantly reduced in all of water retention, thickness, and bulkiness, and had a strong but strong feeling.

  Although the description of the embodiment has been completed above, the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the scope of the invention.

1 Nonwoven wiper 10, 20 Base sheet (composite type nonwoven fabric)
12, 22 Heat-fusible cellulosic fiber web 12a, 22a Part of heat-fusible cellulosic fiber web 14, 24 Synthetic fiber-based web 30 Joint 35 Recess 40 Preliminary laminate MD Non-woven fabric conveyance direction CD Width direction

Claims (10)

Including a plurality of base material sheets in which a heat-fusible cellulosic fiber web in which heat-fusible fibers are blended with cellulosic fibers and a synthetic fiber-based web composed of synthetic fibers are laminated and hydroentangled;
A non-woven wiper characterized in that the base sheets are superposed and the base sheets are joined together via a joint where the heat-fusible fibers are melted and solidified.   In the width direction perpendicular to the conveying direction at the time of manufacturing the nonwoven fabric wiper, the arrangement of the joint portion is designed so that there is no full-width non-joint portion other than the joint portion. The nonwoven fabric wiper according to claim 1, wherein   The nonwoven fabric wiper according to claim 1 or 2, wherein an arrangement area ratio of the joint portion is 4 to 25%.   The nonwoven fabric wiper according to any one of claims 1 to 3, wherein the nonwoven fabric wiper includes two base sheets and is overlaid in a form in which the synthetic fiber webs face each other.   The nonwoven fabric wiper according to any one of claims 1 to 3, wherein the nonwoven fabric wiper includes a plurality of the base sheet, and the heat-fusible cellulosic fiber webs are superposed in a form of front and back surfaces. Nonwoven wiper according to any one of claims 1 to 5, the basis weight of the base sheet is 40~90g / m ^2, characterized in that. Preparing a plurality of base material sheets in which a heat-fusible cellulosic fiber web in which heat-fusible fibers are blended with cellulosic fibers and a synthetic fiber web made of synthetic fibers are laminated and hydroentangled;
After individually feeding out the plurality of substrate sheets, a laminate forming step of obtaining a preliminary laminate by superimposing the substrate sheets;
While sandwiching the preliminary laminate, the base sheets are bonded together by a bonding portion in which at least a part of the heat-fusible fiber is melted and solidified by performing a partial heat treatment at a predetermined arrangement area ratio. A non-woven wiper manufacturing method comprising: a fixing process step for fixing the non-woven wiper.   The method for manufacturing a nonwoven fabric wiper according to claim 7, wherein the nonwoven fabric wiper is manufactured by using the two base sheet and superposed in a form in which the synthetic fiber webs face each other.   The method for producing a nonwoven fabric wiper according to claim 7, comprising a plurality of the base sheet, wherein the heat-fusible cellulosic fiber webs are superposed in a form of front and back surfaces.   The method for manufacturing a nonwoven fabric wiper according to any one of claims 7 to 9, wherein the heating means for performing the heat treatment is a heater device or an ultrasonic device.

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