JP4870284B2 - Composite sheet having moisture permeability and absorbent article using the composite sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite sheet excellent in moisture permeability and strength, and an absorbent article using the composite sheet as a back sheet.
[0002]
[Prior art]
As a moisture permeable resin film, a non-porous moisture permeable resin film of a block copolymer of a soft component and a hard component is known. Since this non-porous moisture-permeable resin film has a liquid blocking effect and has moisture permeability, it can be used for a back sheet of an absorbent article, for example. However, since the non-porous moisture-permeable resin film has a low film strength, there is a risk of tearing or pinholes when used alone.
[0003]
Therefore, as a material used for a back sheet of an absorbent article, Japanese Patent Application Laid-Open No. 11-138673 discloses a perforated resin film in which an inorganic filler is mixed and stretched to form a large number of fine holes, and the non-porous moisture permeability. A moisture permeable film laminated with a film is disclosed. Japanese Patent Application Laid-Open No. 2001-79970 discloses a partially bonded moisture-permeable nonwoven fabric and the non-porous moisture-permeable film.
[0004]
[Problems to be solved by the invention]
In the conventional publication, the low strength of the non-porous moisture-permeable resin film can be compensated by laminating the non-porous moisture-permeable resin film on the porous resin film or the nonwoven fabric.
[0005]
However, what is disclosed in the above-mentioned conventional publication is used in a flat form in a state where a non-porous moisture-permeable resin film is laminated on a porous resin film or a non-woven fabric. Is also bad. In particular, the non-porous moisture-permeable resin film has a tackiness peculiar to an elastomer, so that the touch is poor and the texture is lowered when used as a back sheet of an absorbent article such as a disposable diaper.
[0006]
The present invention solves the above problems, and aims to provide a composite sheet capable of maintaining a high moisture permeability and strength and exhibiting a cross-like texture, and an absorbent article using the composite sheet. To do.
[0007]
[Means for Solving the Problems]
This onset Ming, a nonporous moisture-permeable resin film, and a perforated resin film moisture permeability higher than the no AnaToru permeable resin film which many micropores are formed by the filler is mixed stretched laminated, the imperforate moisture and permeable resin film and said perforated resin film is formed wrinkles on the perforated resin film is bonded at least in part, further non-woven fabric to the non AnaToru-permeable resin film of the laminated film Is a composite sheet characterized by being bonded .
[0008]
In this composite sheet, the non-porous moisture-permeable resin film exhibits liquid barrier properties, and the porous resin film exhibits strength, and thus has moisture permeability, liquid barrier properties, and strength. Moreover, by forming wrinkles on the surface, it has a cross-like appearance and the touch is soft.
[0009]
For example, the non-porous moisture-permeable resin film is formed of an elastomer resin containing a block copolymer of a soft component and a hard component, and at least the porous resin film due to the shrinkage force of the non-porous moisture-permeable resin film A cocoon is formed .
[0010]
By utilizing the shrinkage force of the elastomer resin, wrinkles can be developed throughout the composite film.
[0016]
The composite sheet has an overall thickness and a texture, and can exhibit a soft texture due to wrinkles. It also has moisture permeability and liquid blocking function.
[0018]
The square root of the product of the tensile strength of MD and the tensile strength of CD is preferably 2000 mN or more per 25 mm width.
[0019]
In particular, when the non-porous moisture-permeable resin film and the porous resin film are combined, the strength of the film is higher than that when the non-porous moisture-permeable resin film is used alone.
[0020]
Further, the moisture permeability of no AnaToru permeable resin film, if it is 1500g / m ^2/24 hours or more, when used, such as in absorbent articles, can prevent stuffiness due human perspiration.
[0021]
Moreover, when the non-porous moisture-permeable resin film has a water pressure resistance of 1000 mmAq or more, when it is used as a back sheet of an absorbent article, the effect of blocking the discharged liquid from the human body can be sufficiently exhibited.
[0022]
Further, the absorbent article of the present invention is an absorbent article in which a liquid absorbent layer is provided between a liquid-permeable top sheet and a back sheet, wherein the back sheet is formed of any one of the composite sheets described above. It is characterized by that.
[0023]
When the composite sheet is used as a back sheet, the back sheet is excellent in water resistance, moisture permeability and strength, and the appearance is cross-like and has a good texture.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
As the composite sheet of the present invention, for example, a laminate of a nonporous moisture-permeable resin film and a perforated sheet can be used.
[0025]
As the non-porous moisture-permeable resin film used for the composite sheet, for example, an elastomer resin containing a block copolymer of a hard component and a soft component can be selected. A block copolymer of a soft component and a hard component has high moisture permeability, and in particular, since the soft component is amorphous, moisture permeability can be increased.
[0026]
The elastomer resin containing the block copolymer of the soft component and the hard component is preferably a polyester-based elastomer resin. In this case, the soft component includes at least one of polyester and polyether, and the hard component is polyester. Something is good.
[0027]
As the soft component, those having a glass transition point of 20 ° C. or lower are preferable, and examples thereof include aliphatic polyesters or polyethers, or copolymers of aliphatic polyesters and polyethers.
[0028]
The aliphatic polyester is, for example, a polyester of an aliphatic dicarboxylic acid and an aliphatic glycol. The aliphatic dicarboxylic acid is at least one carboxylic acid selected from succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid and the like. The aliphatic glycol is one or more polyhydric alcohols selected from ethylene glycol, propylene glycol, butylene glycol and the like. The polyether is, for example, polyalkylene glycol, and is at least one selected from polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and the like.
[0029]
The polyester serving as the hard component is preferably a polyester having a glass transition point of 50 ° C. or higher. This hard component preferably contains an aromatic ring in at least one of carboxylic acid and glycol, for example, polyester of aromatic dicarboxylic acid and aliphatic glycol.
[0030]
The aromatic dicarboxylic acid is phthalic acid, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenyl-4,4′-naphthalenedicarboxylic acid 3,3′-dimethyldiphenyl-4,4′-dicarboxylic acid, 4,4′-diphenylsulfone dicarboxylic acid, 4,4′-diphenoxyethanedicarboxylic acid, and the like. The aliphatic glycol is one or more polyhydric alcohols selected from ethylene glycol, propylene glycol, butylene glycol and the like.
[0031]
In particular, in the present embodiment, a structural unit having an aromatic polyester component as a hard component and an aliphatic polyether component as a soft component is preferable. Specifically, perprene (trademark manufactured by Toyobo Co., Ltd.) can be selected.
[0032]
In the non-porous moisture-permeable resin film, a resin material in which an olefin resin is mixed with a block copolymer of the soft component and the hard component can be used.
[0033]
The olefin resin can be selected from those selected from ethylene or propylene polymers or copolymers, or a mixture thereof. For example, the olefin resin is LDPE (low density polyethylene), LLDPE (linear low density polyethylene), HDPE (high density polyethylene), or a mixture thereof.
[0034]
The resin in which the block copolymer and the olefin resin are mixed is melt-extruded, formed into a sheet shape by a die, and uniaxially or biaxially stretched as necessary to form a film.
[0035]
By using a block copolymer of the soft component and the hard component, vapor permeability can be achieved. Moreover, since the block copolymer is obtained by copolymerizing a single polymer having a different soft component and hard component, the film containing the block copolymer is rich in stretchability.
[0036]
The non-porous moisture-permeable resin film preferably has a thickness of 5 μm to 100 μm, and more preferably 5 μm to 30 μm. When the film thickness is less than 5 μm, the strength is inferior, and when the film thickness exceeds 100 μm, the moisture permeability and texture are deteriorated. The moisture permeability of the non AnaToru-permeable resin film, is preferably 1500g / m ^2/24 hours or more, is less than 1500g / m ^2/24 hours, more likely stuffy not possible to obtain sufficient moisture permeability . The moisture permeability described here is measured by the test method shown in the following (1). Moreover, it is preferable that the water-proof pressure of a non-porous moisture-permeable resin film is 1000 mmAq or more, and when it is less than 1000 mmAq, the liquid blocking property may be impaired.
[0037]
The perforated sheet can be selected from a resin film or a nonwoven fabric having a moisture permeability higher than that of the non-porous moisture-permeable resin film. Examples of the resin film include those in which a filler is mixed with a polyolefin-based or polyester-based thermoplastic resin such as LDPE (low density polyethylene), LLDPE (linear low density polyethylene), MDPE (medium density polyethylene), etc. It is a moisture-permeable material in which a large number of micropores are formed by stretching this film. The filler used here can be selected from inorganic fillers such as minerals such as calcium carbonate, barium sulfate, calcium phosphate, talc, silica, activated carbon, or synthetic minerals.
[0038]
As the nonwoven fabric, a nonwoven fabric formed of thermoplastic fibers (heat-fusible fibers) or a nonwoven fabric containing thermoplastic fibers can be used, and is moisture permeable. The thermoplastic fiber may be a single polyolefin resin such as PE (polyethylene) or PP (polypropylene), or a polyester resin such as PET (polyethylene terephthalate), or a composite fiber of PE and PET. , And a composite fiber of PE and PP, for example, a composite fiber having a core-sheath structure in which the core is PET or PP and the sheath is PE. The nonwoven fabric can be formed using a spunbond method, a spunlace method, a melt blown method, or the like.
[0039]
The basis weight of the nonwoven fabric is preferably 5 g / m ² or more and 100 g / m ² or less, more preferably 5 g / m ² or more and 30 g / m ² or less. If the basis weight is less than 5 g / m ² , the moisture permeability becomes excessive, and if the basis weight exceeds 100 g / m ² , the moisture permeability and texture deteriorate.
[0040]
In place of the non-woven fabric, a woven or knitted fabric such as cotton, hemp or silk may be used. A woven fabric is a combination of warp yarns and weft yarns in a certain manner, and a knitted fabric is a loop made of yarn, which is held back and forth and left and right.
[0041]
The moisture permeability of the porous sheet, the non AnaToru higher than permeable resin film is preferably 100g / m ^2/24 hours or more. When the perforated sheet is a resin film, the film thickness is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 30 μm or less. If the film thickness is less than 5 μm, sufficient strength cannot be obtained. In addition, when it exceeds 100 μm, moisture permeability and texture deteriorate.
[0042]
FIG. 1 shows a cross-sectional view of a composite sheet of a reference example . This composite sheet 20 </ b> A shows a state in which the non-porous moisture-permeable resin film 21 and the perforated sheet 22 are partially joined and wrinkles are developed in the perforated sheet 22. As described above, the perforated sheet 22 at this time is a resin film 22a in which a filler is mixed and a large number of micropores 23 are formed by stretching.
[0043]
In the composite sheet 20A, as shown in FIG. 2, the non-porous moisture-permeable resin film 21 is stretched in the step A, and the non-porous moisture-permeable resin film 21 is partially joined to the resin film 22a in the stretched state. Laminate (step B). Then, by releasing the tensile force, the resin film 22a is contracted together with the non-porous moisture-permeable resin film 21 to form wrinkles on the resin film 22a (Step C).
[0044]
In the composite sheet 20A, when bonding the non-porous moisture-permeable resin film 21 and the resin film 22a, adhesion by an adhesive or adhesion by heat can be selected.
[0045]
In the adhesive bonding, a hot melt adhesive (HMA) can be used, and this HMA can be applied to the non-porous moisture-permeable resin film 21 and / or the resin film 22a in a spiral shape or a curtain shape and bonded. it can. In this case, it is preferable that the HMA contains an effective resin for adhering an ester resin of the same quality as the non-porous moisture-permeable resin film 21 and an olefin resin of the same quality as the resin film 22a. .
[0046]
In the adhesion using an adhesive, one or both of the non-porous moisture-permeable resin film 21 and the resin film 22a may be kneaded. For example, Admer (manufactured by Mitsui Chemicals, Inc.) is used. it can. The kneading amount of the adhesive at this time is preferably 50% or less of the base material of the non-porous moisture-permeable resin film 21 (or the base material of the resin film 22a) in terms of mass, and 5 in view of moisture permeability. It is preferable to set it to -15%.
[0047]
The adhesive coating amount of the perforated sheet 22 is preferably 50% or less in terms of basis weight (mass per area (g / m ² )). If the coating amount exceeds 50%, the moisture permeability and texture deteriorate, so it is desirable to be 5 to 15% in consideration of moisture permeability. In addition, the heat bonding may be heat bonding in an embossed shape, or may be bonding at a point or surface.
[0048]
In the composite sheet 20A, the adhesion strength between the non-porous moisture-permeable resin film 21 and the resin film 22a is preferably 10 mN / 25 mm or more in both cases of adhesion by an adhesive and adhesion by heat. In consideration, it is preferably 400 mN / 25 mm or more. Here, the adhesive strength is a value measured by the following test method (2).
[0049]
FIG. 3 is a cross-sectional view showing a composite sheet of a reference example . In the composite sheet 20B, the non-porous moisture-permeable resin film 21 and the resin film 22a are partially joined similarly to the composite sheet 20A, and wrinkles appear on the non-porous moisture-permeable resin film 21 side. It is a state of being.
[0050]
In this composite sheet 20B, a tensile force is applied to the resin film 22a mixed with the filler to form a plurality of fine holes 23 in the resin film 22a, and when the fine holes 23 are formed, the non-porous moisture-permeable resin film 21 is formed. The non-porous moisture-permeable resin film 21 is made to develop wrinkles by partially joining and overlapping, then releasing the tensile force and shrinking the resin film 22a.
[0051]
FIG. 4 is a cross-sectional view showing a composite sheet of a reference example . This composite sheet 20C is obtained by partially joining and laminating the non-porous moisture-permeable resin film 21 and the non-woven fabric 22b to express wrinkles in the non-woven fabric 22b. In this case, wrinkles are expressed in the nonwoven fabric 22b by partially joining the nonwoven fabric 22b with a tensile force applied to the non-porous moisture-permeable resin film 21.
[0052]
In addition, in the composite sheet which laminated | stacked the said non-porous moisture-permeable resin film 21 and the nonwoven fabric 22b, the nonwoven fabric which has a stretching property is used, and in the state which extended this nonwoven fabric, the said non-porous moisture-permeable resin film 21 and partial The non-woven breathable resin film 21 may be wrinkled by bonding, releasing the tensile force applied to the nonwoven fabric, and shrinking the nonwoven fabric.
[0053]
In the composite sheets 20A, 20B, and 20C described above, the square root of the product of the MD tensile strength and the CD tensile strength of the perforated sheet 22 is preferably 2000 mN or more, more preferably 4000 mN or more per 25 mm width. The tensile strength of the perforated sheet 22 is preferably 1.1 times or more, more preferably 1.3 times or more of the tensile strength of the non-porous moisture-permeable resin film 21. By setting the tensile strength within the above range, the strength when a composite sheet having a thinner thickness than that of the conventional one is obtained can be equal to or exceeding that of the conventional one. Further, at this time, when the film thickness of the composite sheet is 30 μm or less, what is preferable in terms of texture can be obtained.
[0054]
The tensile strength was measured by the following test method (3). However, the MD direction is a direction parallel to the flow direction of the web when the nonwoven fabric is formed, and the CD direction is a direction orthogonal to the flow direction of the web.
[0055]
Figure 5 is a sectional view showing a double case sheet of the present invention. The composite sheet 20D has a three-layer structure in which a nonwoven fabric 22c is further laminated on the composite sheet 20A.
[0056]
This composite sheet 20D is obtained by laminating a non-woven fabric 22c on the non-porous moisture-permeable resin film 21 side on a laminated film of a non-porous moisture-permeable resin film 21 and a porous resin film (resin film) 22a. In this case, it can be obtained by laminating the non-woven fabric 22c after laminating the non-porous moisture-permeable resin film 21 and the perforated resin film 22a to express wrinkles in the perforated resin film 22a.
[0057]
FIG. 6 is a cross-sectional view showing a composite sheet of a reference example . This composite sheet 20E has the same three-layer structure as the composite sheet 20D, and causes wrinkles to develop in the nonwoven fabric 22c by the shrinkage force of the laminated film of the non-porous moisture-permeable resin film 21 and the perforated resin film 22a. It has become.
[0059]
The composite sheets 20A to 20E formed as described above can be provided with moisture permeability, liquid blocking properties, and strength, and the skin can be softened by forming wrinkles on the surface. However, the present invention is not limited to these, and may be more than three layers.
[0060]
FIG. 7 is a perspective view showing a pants-type disposable diaper as an example using the composite sheet of the present invention.
[0061]
The disposable diaper 1 of the present invention shown in FIG. 7 includes a front surface portion 2A applied to the wearer's abdomen during use, a rear surface portion 2C applied to the buttocks and / or back during use, and both side portions 4B and 4B during use. Has an intermediate part 2B applied to the thigh.
[0062]
The disposable diaper 1 includes a liquid-permeable top sheet 10 directed toward the liquid receiving side of the wearer, a liquid-impervious back sheet 11 directed outward, and the top sheet 10 and the back sheet 11. It is comprised with the laminated body with the absorption core 12 slightly smaller than those sheets pinched | interposed. The top sheet 10 and the back sheet 11 are joined to each other around the absorbent core 12 by a hot melt adhesive or the like. In this case, the composite sheets 20 </ b> A to 20 </ b> E of the present invention can be applied to the back sheet 11.
[0063]
A waist opening 8 is formed at each edge of the front surface portion 2A and the rear surface portion 2C, that is, at the waist end portions 3A and 3C. Further, leg openings 9 are formed on both side portions 4B of the intermediate portion 2B to form a pants shape as shown in FIG.
[0064]
An elastic member (elastic band) 15 is attached to the waist ends 3A and 3C in the lateral direction, and a waist gather is formed in the waist opening 8 by the elastic contraction force of the elastic member 15 as shown in FIG. . Leg-side elastic members (elastic bands) 16 are attached to the both side portions 4B. As shown in FIG. 1, leg gathers (leg-side) are formed around the leg openings 9 by the elastic contraction force of the elastic members 16. Cuff) is formed.
[0065]
The top sheet 10 is formed of hydrophobic fibers, hydrophilic fibers, and the like that have been subjected to hydrophilic treatment, such as point bonds, air throughs, spun bonds, and spun lace nonwoven fabrics. Alternatively, a top sheet may be formed by stacking a cushion layer made of a bulky nonwoven fabric on the nonwoven fabric.
[0066]
Below, each test method in this invention is shown.
(1) Water permeability 20 cc of water measured with a graduated cylinder is put into a predetermined cup, the composite sheet (sample) is placed on a position concentric with the cup, the cup is placed on the cup base, and the ring is placed on the composite sheet. Place the guide on the top of the cup base.
[0067]
Then, the weight is placed on the ring, and the guide is pulled up and removed. Put the brazing filler metal in the pan, melt it, scoop out the wax with a spoon, and pour it into the groove on the periphery of the cup, taking care not to melt the composite sheet, and seal the edges of the composite sheet. After sealing, turn the cup down and check for water oozing.
[0068]
The mass after the sample is left for 30 minutes in a constant temperature and humidity device (20 ° C., 60% RH) is measured. Further, the sample is left in a constant temperature and humidity device (40 ° C./60% RH) for 24 hours, a sample is taken out after 24 hours, and the mass after being left in a constant temperature and humidity device (20 ° C./60% RH) for 30 minutes. Measure and let the mass at this time be B. From the formula (B-A) / (π × 0.03 × 0.03), was calculated moisture permeability (g / m ^2/24 hours). However, the numbers after the decimal point are rounded off.
[0069]
The sealing material used was a mixture of beeswax (yellow) and paraffin (white) in a mixing ratio of 6: 4.
[0070]
(2) As an adhesive strength test piece (composite sheet), a sample having a width of 25 mm and a length of 80 mm is randomly collected for N number, and 30 mm of the peeling direction of 80 mm is carefully peeled off to the upper layer and the lower layer. When the nonwoven fabric is not provided on the composite sheet, a sample similar to the above is taken in an arbitrary direction, and 30 mm of the peeling direction of 80 mm is carefully peeled off from the upper layer and the lower layer. Using a constant speed extension type tensile tester (Shimadzu Autograph; AG-100B), the upper and lower layers of the sample were sandwiched between the upper and lower chucks of the tester, and measurement was performed. As test conditions at this time, the peel test mode was set, the grip interval was 30 mm, the tensile speed was 100 mm / min, the maximum load point, the upper limit average load, the lower limit average load, the average load, the maximum load average were measured, and the average of the maximum load Was calculated. In addition, when a test piece is 3 layers, it carries out about each contact bonding layer.
[0071]
(3) Tensile strength A test piece was punched in a strip shape of 25 mm in width and 100 mm in length in each of the MD direction and the CD direction. The center part of this test piece was left over a length of 50 mm, both ends were sandwiched with aluminum foil tape, the test piece aluminum foil tape was sandwiched with a tensile tester, and measurement was performed under conditions of a chuck interval of 50 mm and a tensile speed of 200 mm / min. . At this time, the strength at 5% elongation (g / 25 mm), the strength at yield point (g / 25 mm), the strength at MAX (g / 25 mm), and the elongation at MAX (%) were measured. It was taken as the calculated value. However, all rounded off the decimal point.
[0072]
(4) Water pressure resistance According to the hydrostatic pressure method of method A (low water pressure method) of JIS-L-1092, a 150 mm x 150 mm sample (composite sheet) is taken, and the front side of the sample faces downward (the side in contact with water) ). A wire mesh (3 mesh) was placed on the sample, rubber was further placed, and the clamp was fully tightened. The level device containing normal temperature water was raised at a rate of 60 cm / min, and the water level (unit: cm) of the water pressure gauge (manometer) when water droplets emerged from the surface of the sample was measured. However, the upper limit is set to 100 cm. Measurement was performed with a minimum number of samples of 5.
[0073]
【Effect of the invention】
In this invention demonstrated above, what was excellent in moisture permeability and intensity | strength is obtained, and what has a favorable touch can be obtained by forming a wrinkle on the surface further. As a result, it is not necessary to incorporate a rubber string or the like to give stretchability, so that the cost can be reduced. In particular, when an elastomer resin is used for the non-porous moisture-permeable resin film, it is possible to eliminate the inconvenience that the touch is lowered due to the tackiness characteristic of the elastomer resin.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a composite sheet of a reference example ;
FIGS. 2A, 2B, and 2C are manufacturing process diagrams of the composite sheet shown in FIG.
FIG. 3 is a cross-sectional view showing a composite sheet of a reference example ;
FIG. 4 is a cross-sectional view showing a composite sheet of a reference example ;
5 is a sectional view showing a composite sheet according to the embodiment of the present invention,
FIG. 6 is a sectional view showing a composite sheet of a reference example ;
FIG. 7 is a perspective view showing a pants-type disposable diaper using the composite sheet of the present invention,
[Explanation of symbols]
20A, 20B, 20C, 20D, 20E Composite sheet 21 Non-porous moisture-permeable resin film 22 Perforated sheet 22a Perforated resin film (resin film)
22b, 22c Non-woven fabric 23 Micropore

Claims (6)

And imperforate moisture-permeable resin film, a perforated resin film moisture permeability higher than the no AnaToru permeable resin film which many micropores are formed by the filler is mixed drawn are stacked, the free AnaToru permeable resin film and the and the perforated resin film is formed wrinkles on the perforated resin film is bonded at least in part, are further joined non-woven fabric to the non AnaToru-permeable resin film of the laminated film A composite sheet characterized by that. The non AnaToru permeable resin film is formed of an elastomer resin comprising a block copolymer of the soft component and the hard component, the shrinkage force of the continuously AnaToru-permeable resin film, wrinkles formed in the perforated resin film the composite sheet of claim 1 wherein being. The composite sheet according to claim 1 or 2 , wherein the square root of the product of the tensile strength of MD and the tensile strength of CD is 2000 mN or more per 25 mm width. The composite sheet according to moisture permeability, any one of claims 1 to 3 is 1500g / m ^2/24 hours or more non AnaToru permeable resin film. The water pressure resistance of non AnaToru permeable resin film, a composite sheet according to any one of claims 1 to 4 is at least 1000MmAq. In an absorbent article the liquid absorbent layer is provided between the liquid-permeable top sheet and the back sheet, said back sheet is formed of a composite sheet according to any one of claims 1 to 5 Absorbent article characterized by.

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