JP4017616B2 - Embossed groove formability evaluation method - Google Patents

Description

  The present invention relates to a method for evaluating formability of embossed grooves.

  Conventionally, as absorbent articles such as sanitary napkins, panty liners, incontinence pads, etc., equipped with a liquid-permeable top sheet, a liquid-impermeable back sheet and a liquid-retaining absorbent interposed between both sheets, An embossed groove is formed on the surface of the top sheet (the surface facing the wearer's skin when worn) for the purpose of improving leakage prevention and improving the adhesion to the excretion part by promoting the uplift of the opposite part of the excretion part. It is widely done.

  The embossed groove is formed by absorbing a laminated body in which a top sheet and an absorbent body are laminated, a laminated body in which a top sheet, an absorbent body and a back sheet are laminated, a laminated body in which another sheet is further laminated thereon, and the like. A heatable embossing roll having a protruding portion having a shape corresponding to the shape of the embossed groove on the peripheral surface while transporting in a direction corresponding to a direction connecting the front and rear (hereinafter referred to as a longitudinal direction) when the article is mounted. And a surface-smooth backup roll, the surface sheet side surface is inserted with the embossing roll side, and the laminate is partially squeezed between the ridge and the backup roll surface. Is widely practiced. As for the embossed groove formed in this way, generally, a high pressing part and a low pressing part or a non-squeezing part are arrange | positioned alternately along the longitudinal direction.

  In such an embossing formation method, since the pressing force applied to the embossing roll and the backup roll roll is constant, the absorbent article is crossed in a direction perpendicular to the longitudinal direction (hereinafter referred to as the width direction). When a line is drawn and the length of the part where the transverse line contacts the high-pressure portion is defined as the contact line length, the contact of the embossment in the width direction along the substantially width direction of the absorbent article The line length is relatively long, and the contact line length of the embossment in the longitudinal direction along the substantially longitudinal direction of the absorbent article is relatively short. Therefore, there is a difference between the linear pressure when forming the substantially embossed groove in the width direction and the linear pressure when forming the embossed groove in the substantially longitudinal direction, and the surface sheet is torn at a portion where the linear pressure is high, and the linear pressure is low. The surface sheet tends to float on the part. In addition, when the linear pressure is increased to prevent floating, the surface sheet is likely to be cut at a portion where the linear pressure is low. In particular, such a phenomenon occurs when the heating temperature of the embossing roll cannot be increased in the case where the surface sheet is a non-woven fabric made of a fiber having a low melting point resin as shown in Patent Documents 1 and 2, for example. Cheap.

  In order to prevent the surface sheet from being torn or lifted, the maximum value of the contact line length in the region where the embossment in the width direction along the substantially width direction of the absorbent article exists, and in the substantially longitudinal direction There has been proposed an absorbent article in which a difference from the maximum value of the contact line length in a region where longitudinal embossing is present is within 5 mm (see Patent Document 3).

JP-A-9-108262 JP-A-8-325849 JP 2003-265519 A

  However, according to the test by the present inventors, as in Patent Document 3, even if the difference in the maximum value of the contact line length is suppressed to within 5 mm, the topsheet may not be torn or lifted.

  In addition, in order to obtain embossed grooves with good formability, the process of actually creating an embossing roll, making a prototype, and evaluating the formability is repeated, which increases costs and time. there were.

  Therefore, an object of the present invention is to easily determine whether an embossed groove pattern designed for an absorbent article or the like can be clearly formed in the embossed groove forming process. It is to provide a method for evaluating the formability of a groove.

  According to the present invention, a pattern of embossed grooves for an absorbent article having a liquid-permeable top sheet, a back sheet, and a liquid-retaining absorbent interposed between both sheets is clearly shown in the embossed groove forming step. A method for evaluating the formability of an embossed groove for determining whether or not it can be formed, on the pattern of the embossed groove to be evaluated, a band-like region having a constant width that crosses the absorbent article in the width direction Assuming that the position of the band-like region is moved by a certain distance in the longitudinal direction of the absorbent article, the total area of the embossed part existing in the band-like region is obtained at each position, and the total of the embossed part By providing an embossed groove formability evaluation method for determining whether or not the embossed groove can be clearly formed on the basis of whether or not the maximum value of the area is a certain value or less. , The above purpose One in which was achieved.

  According to the embossing groove formability evaluation method of the present invention, the embossing groove pattern designed for absorbent articles can be clearly formed without causing sheet lifting or cutting in the embossing process. Whether or not it is possible can be easily determined. The determination result can be used for designing an emboss for an absorbent article. It is also possible to evaluate the virtual embossed groove pattern designed on the desk using CAD, etc., so the number of prototypes for evaluation can be reduced, and the speed of commercialization can be increased and the cost can be reduced. become.

The present invention will be described below based on preferred embodiments with reference to the drawings.
First, the sanitary napkin 1 as an example of the absorbent article in the present invention will be described. As shown in FIGS. 1 and 2, the sanitary napkin 1 includes a liquid-permeable top sheet 2, a liquid-impermeable back sheet 3, and a liquid-retaining absorbent body 4 interposed between both sheets. However, it is formed substantially vertically.
The absorber 4 is fixed in a state of being sandwiched between the top sheet 2 and the back sheet 3. The top sheet 2 forms a skin contact surface. The left and right side edges in the longitudinal direction of the top sheet 2 are wound down to the surface side of the absorber 4 on the back sheet 3 side and are fixed between the absorber 4 and the back sheet 3 with an adhesive. The front sheet 2 and the back sheet 3 extend from both longitudinal ends of the absorbent body 4 at the longitudinal front and rear end portions of the napkin 1, and the extended portions are joined to each other by heat sealing or the like to form the seal portion 5. Forming.

On the surface of the napkin 1 on the surface sheet 2 side, as shown in FIG. 2, embossed grooves 6 are formed by integrally pressing the surface sheet 2 and the absorber 4 by embossing. As shown in FIG. 1, the embossed groove 6 has a vertically long shape in the longitudinal direction of the napkin 1 as a whole.
As shown in FIG. 2, a high pressing portion 61 and a low pressing portion 62 are formed on the bottom surface of the embossing groove 6, and the high pressing portion 61 is formed intermittently along the longitudinal direction of the embossing groove 6. Has been. Specifically, at the central portion in the width direction of the embossed groove 6, the high-pressure squeezed portions 61 and the low-pressure squeezed portions 62 are alternately arranged along the longitudinal direction of the embossed groove 6. In the part, the low-pressure squeezed part 62 is continuous.
The high-pressure squeezed portion 61 is a portion squeezed more strongly than the low-pressure squeezed portion 62 when the embossed groove 6 is formed. As shown in FIGS. 2B and 2C, the high-pressure squeezed portion 61 is more compacted than the low-pressure squeezed portion 62 and is thinner than the low-pressure squeezed portion 62.

An embodiment of the embossing groove formability evaluation method of the present invention will be described.
In one embodiment of the embossed groove formability evaluation method, an embossed groove pattern is determined. That is, the shape of the embossed groove in plan view, in particular, the shape of the portion existing in the vicinity of the longitudinal end of the absorbent article, and the shape, size, arrangement interval, etc. of the embossed part corresponding to the high-pressure portion of the embossed groove are determined. Determine as appropriate. When it is desired to form an embossed groove from a high-pressure squeezed portion and a low-pressure squeezed portion, the shape, size, arrangement interval, etc. of the high-pressure squeezed portion in the embossed groove are appropriately determined, and the high-pressure squeezed portion and the low-pressure squeezed portion are formed at the bottom Design embossed grooves with The embossed groove as an evaluation target may be a design (virtual) designed on a desk using CAD or the like.

In the embossed groove formability evaluation method, it is determined whether or not the embossed groove pattern designed in this way can be clearly formed in the embossed groove forming step.
Specifically, as shown in FIG. 3, on the embossed groove pattern to be evaluated, assuming a band-like region 7 having a constant width across the absorbent article in the width direction, the position of the band-like region 7 is It moves to the longitudinal direction of this absorbent article, and the total area of the embossed part which exists in this strip | belt-shaped area | region is calculated | required about each position.
The embossed part in this invention is a part corresponding to the high pressing part of the embossing groove | channel of the absorbent article produced based on this design method. A high pressure part means the part by which the total thickness of a surface sheet and an absorber is squeezed to thickness 10% or less of the same total thickness in the part which is adjacent to an embossing groove | channel and is not squeezed. Therefore, when calculating | requiring the total area of the embossed part which exists in the strip | belt-shaped area | region 7, the total area of the part corresponding to a high pressing part is calculated | required.
However, in the case of what was designed on a desk using CAD etc., when the actual product is squeezed, the total thickness of the topsheet and the absorber is the same total thickness in the unsqueezed part adjacent to the embossed groove. When the portion calculated when squeezed to 5% or less is the embossed portion (the portion corresponding to the high-pressure squeezed portion) and the total area in the belt-like region is to be calculated, the total area of the embossed portion thus determined is Ask.
As in the napkin of the present embodiment, when the embossed groove is composed of the high-pressure squeezed part 61 and the low-pressure squeezed part 62, the area of the part where the thickness is in the above range in the high-pressure squeezed part 61, which is a more strongly squeezed part. To sum.

  Then, it is determined whether or not the emboss can be clearly formed on the basis of whether or not the maximum value of the total area of the embossed portion is equal to or less than an arbitrarily set value. The expression “based on whether or not it is less than or equal to the set value” includes “based on whether or not it is less than or equal to the set value” or “based on whether or not it is less than the set value”. This includes the case where it is used as a reference.

For example, in a preferable method for manufacturing an absorbent article, the embossing roll has a diameter of 130 to 260 mm, the pressure during pressing is set to 1.5 to 6 MPa, and the heating temperature of the embossing roll is set to 80 to 200 ° C. In this case, it is preferable that the width of the belt-like region 7 is 3 mm, and the belt-like region 7 is moved by 1 mm, and the maximum value of the total area is preferably a value set arbitrarily at 9 mm ² or less.
Arbitrary setting at 9 mm ² or less means that it can be arbitrarily set depending on the level of the embossing groove moldability required. For example, when the moldability of the embossed groove equivalent to that of the absorbent article described above is desired, the set value is 9 mm ^2, and when a higher level of moldability is required, a smaller value is set. . By setting severe conditions, it is possible to improve the proportion of the absorbent article in which the embossed grooves can be clearly formed during actual production.

  The embossing groove formability evaluation method can be implemented by a virtual method using CAD or the like. As a result, it is possible to minimize the number of times that the embossing roll is prototyped or the prototype test is performed for the evaluation of formability, and the cost and time can be reduced.

  The moldability evaluation method of the present invention can be particularly preferably used for evaluation of the embossed groove of an absorbent article manufactured by the following manufacturing method.

  In this manufacturing method, as shown in FIG. 4, an embossing roll 83 having a protruding strip portion 8 (convex portion) having a shape corresponding to the shape of the embossing groove 6, and a smooth surface backup arranged opposite to the embossing roll 83. An embossing device 80 having a roll 84 is used. The embossing forming apparatus is provided with a heating means capable of heating the ridges 8 of the embossing roll to a predetermined temperature and maintaining the state. The ridges 8 are positioned at the tip of the high-pressure part 81 having a substantially flat tip surface and between the adjacent high-pressure parts 81 and on both sides of the high-pressure part 81, And a low pressurizing portion 82 having a step difference between the two. The high pressurization part 81 is intermittently arrange | positioned in the direction where the protruding item | line part 8 is extended. The front end surface of the high pressurizing part 81 corresponds to the embossed part in the present invention.

The pressing pressure by the embossing roll 83 and the backup roll 84 is preferably 1.5 to 6 MPa, and more preferably 3 to 6 MPa in the case of a material having a low melting point of the topsheet. At such a pressure, the embossed groove is likely to float and the top sheet is cut off, but the maximum total area of the convex end surface (the upper end surface of the high pressurizing portion 81) corresponding to the embossed portion is 9 mm ^2. By making the following, such inconvenience can be prevented.

And the laminated body 10 which consists of the elongate surface sheet 2 and the absorber 4 arrange | positioned intermittently in the longitudinal direction of this surface sheet 2 is conveyed continuously in the longitudinal direction corresponding to the longitudinal direction of the napkin 1. Then, between the embossing roll 83 and the backup roll 84 heated to a predetermined temperature, the surface sheet side surface is inserted into the embossing roll side. Thereby, it has the high pressure part 61 (refer FIG. 2) squeezed by the high pressurization part 81 in the laminated body, and the low pressing part 62 (refer FIG. 2) compressed by the low pressurization part 82 in the bottom face. Embossed grooves 6 are formed. The embossed groove 6 is formed in a portion where the top sheet 2 and the absorbent body 4 overlap. Then, the back sheet 3 is laminated and bonded on the surface of the laminate on which the embossed grooves 6 are formed, and then the front and back sheets are heat-sealed between the adjacent absorbers and the heat seal portion. The napkin 1 is obtained by cutting into individual napkin dimensions. You may pass through the embossing formation apparatus 80 in the state which laminated | stacked the back surface sheet 3 on the surface at the side of the absorber 4 of the laminated body 10. FIG.

  The present invention is particularly effective when a sheet material containing fibers made of a low melting point resin is used as the top sheet. When using a sheet material containing fibers made of low-melting point resin as the top sheet, the fibers cannot be solidified, and the fibers may remain cut and clear embossing may not be obtained. It is preferable that the embossing satisfies the above-mentioned conditions, but it is possible to form a clear emboss without causing the surface sheet to float even at such a temperature. it can.

  The low-melting-point fiber is a low-melting-point resin, a core-sheath type composite fiber whose sheath component is a low-melting point resin, a side-by-side type composite fiber, Any of these components comprising a low melting point resin is included. Examples of the low melting point resin include resins having a melting point of 150 ° C. or lower, such as polyethylene resins and ethylene-propylene random copolymers. The content rate of the fiber which consists of low melting-point resin in a sheet | seat material can be 60-100%, for example, or 80-100%.

  As a sheet material composed of fibers composed of a low melting point resin, a nonwoven fabric obtained by making a fiber composed of a low melting point resin into a nonwoven fabric by a thermal fusion method, a hydroentanglement method, a needle punch method, a solvent bonding method, etc. Nonwoven fabrics obtained by a method such as a spunbond method or a melt blown method are preferably used. Such a nonwoven fabric may be used individually by 1 type, and can laminate | stack two or more types, and can join and use them partially. Moreover, what laminated | stacked the nonwoven fabric and the fiber web obtained by the card | curd method, and joined both partially etc. can also be used.

In addition, as the absorber 4, what consists only of fiber materials, such as a pulp fiber, what consists of a fiber material and a highly water-absorbing polymer, etc. can be used. The existence form of the superabsorbent polymer in the case of including the fibrous material and the superabsorbent polymer is sandwiched between the nonwoven fabric and the fibrous web made of the fibrous material, even if it is held in a dispersed state in the fiber gap of the fibrous material. Also good. The fiber material may be in the form of a nonwoven fabric. Examples of fiber materials include hydrophilic fibers such as pulp fibers, rayon, cotton, and cellulose acetate, polyolefin fibers such as polyethylene and polypropylene, polyester fibers such as polyethylene terephthalate, condensation fibers such as polyamide, polyvinyl chloride, and polyvinyl acetate. And vinyl monomer polymer fibers. Hydrophobic fibers are usually used after being hydrophilized. Examples of the superabsorbent polymer include sodium polyacrylate, (acrylic acid-vinyl alcohol) copolymer, cross-linked sodium polyacrylate, (starch-acrylic acid) graft copolymer, and (isobutylene-maleic anhydride). Examples include copolymers and saponified products thereof, polyaspartic acid, and the like.
As a forming material of the back sheet 3, various known materials (for example, a resin film) used in the absorbent article can be used without any particular limitation.

Although one embodiment of the present invention has been described, the present invention can be modified as appropriate without departing from the spirit of the present invention.
For example, the absorbent article in the present invention may be a panty liner, an incontinence pad, a disposable diaper, etc. in addition to a sanitary napkin. Further, the embossing is not limited to an annular shape, and for example, a region continuous in the longitudinal direction near the center of the absorbent article and a region continuous in the width direction of the absorbent article may be discontinuous. However, it is preferable that the protrusions for forming both regions are provided on the same embossing roll.

[Example 1]
Three types of embossed grooves for napkins were designed on the desk. The first embossed groove has a planar shape shown in FIG. 5A, the second embossed groove has a planar view shape shown in FIG. 5B, and the third embossed groove has the shape shown in FIG. It had a planar view shape shown in (c). In any case, the shape of the embossed groove was symmetrical on both the left and right sides in the width direction of the napkin. 5A to 5C, the horizontal direction in each figure is the flow direction during embossing.
For each of the first to third embossed grooves, on the embossed groove, a band-like region having a width of 3 mm that crosses the napkin in the width direction is assumed, and the belt-like region is moved from one end of the portion where the embossed groove is formed. The total area of the embossed portions existing in the belt-like region was determined for each position by moving 1 mm toward the end. The results are shown in FIGS. 6 and 7 for the first and second embossed grooves. In FIGS. 6 and 7, each position where the total area of the embossed portion is obtained is indicated by a distance from the reference position, with the position 1 mm outside the one end of the embossed groove as the reference position. Moreover, in Table 1, the maximum value of the high pressing part contact area was shown about each embossed groove | channel.
Also, a line that crosses the napkin in the width direction is drawn, and the total length of the portion where the transverse line contacts the embossed portion on the transverse line is defined as the contact line length, and the transverse line is 1 mm from the reference position. The contact line length at each position was measured by moving each time, and the results are also shown in FIGS.

[Evaluation of formability]
Using the embossing rolls in which the embossing protrusions were formed in the pattern of each embossing groove, 50 or more napkins were continuously produced using a surface sheet, an absorbent body, and a back sheet, which will be described later. The state of the embossed grooves was observed with the naked eye for 50 napkins in the middle part. The moldability of the embossed groove (the quality of the embossed groove) was evaluated according to the following evaluation criteria, and the number of napkins evaluated in each of 50 napkins is shown in Table 1.
(Evaluation criteria)
○: Embossed grooves are clearly formed.
(Triangle | delta): Although a surface sheet does not float, the clarity of the pattern of an embossing groove | channel is a little weak.
X: The surface sheet has floated.

  In Table 1, the maximum value of the contact line length is determined by the longitudinal center portion 67 where the portion 65 extending in the substantially longitudinal direction of the embossed groove 6 exists and the portion 63 extending in the generally width direction of the embossed groove 6. It is divided and shown in the both ends 66 in the longitudinal direction. Moreover, about the maximum value of the total area (embossed part contact area) of the embossed part which exists in a strip | belt-shaped area | region, the maximum value in the whole which combined the longitudinal direction center part 67 and the both ends 66 of the longitudinal direction was shown.

The following were used for the top sheet, the absorber and the back sheet.
[Surface sheet]
A card web having a basis weight of 20 g / m ² is formed by a card method using a core-sheath composite fiber [trade name NBF-SH, 2.2 dtex × 51 mm] manufactured by Daiwa Boseki Co., Ltd. as a first fiber layer, and further air The nonwoven fabric was made by the through method. A card web having a basis weight of 20 g / m ² was formed by a card method using a latent spiral crimped fiber (trade name: CPP, 2.2 dtex × 51 mm) manufactured by Daiwabo Co., Ltd. as a second fiber layer. Overlapping the first and second layers of unemployed fabric, subject them to hot embossing with a dot pattern, and then spray heat onto the laminate from above and below to thermally shrink the nonwoven fabric for forming the second fiber layer. It was. The multi-layer unwoven cloth thus obtained (basis weight 68 to 75 g / m ² ) was used as a top sheet. The top sheet was laminated with the absorbent body with the nonwoven fabric side containing the heat-crimpable fiber being the absorbent body side.

[Absorbent body] A mixture of pulp fiber and polyacrylic acid crosslinked sodium salt as a superabsorbent polymer wrapped with absorbent paper (tissue paper or the like) was used. The basis weight was 180 to 200 g / m ² .

[Back sheet] A sheet made of a resin film was used.

From the results shown in Table 1, for the first and second embossed grooves where the maximum value of the total area of the embossed portions is 9 mm ² or less, the embossed grooves could be clearly formed in the embossed groove forming step. I understand. On the other hand, for the third embossed groove where the maximum value of the total area of the embossed part exceeds 9 mm ² , the difference in contact line length is relatively low, but the surface sheet floats in the embossed groove forming process. It is easy to see that the embossed groove has poor moldability.
From this, it can be seen that according to the present invention, it is possible to easily determine whether or not the designed embossed groove can be clearly formed in the actual embossed groove forming process.

FIG. 1 is a plan view showing a sanitary napkin as an example of an absorbent article in the present invention. 2A is a plan view showing a part of the embossed groove of the napkin in FIG. 1 in an enlarged manner, and FIG. 2B is a cross-sectional view showing a II cross section in FIG. FIG.2 (c) is sectional drawing which shows the II-II cross section of Fig.2 (a). FIG. 3 is an explanatory view showing a method of assuming the belt-like portion and the moving direction thereof. FIG. 4 is a perspective view showing an embossing device used for forming the embossed groove and a part of the protruding portion for forming the embossing provided on the embossing roll. 5A to 5C are plan views showing the shapes of the first to third embossed grooves used in the examples. FIG. 6 is a graph showing the measurement results of the contact line length and the total embossed area for the embossed groove shown in FIG. FIG. 7 is a graph showing the measurement results of the contact line length and the total embossed area for the embossed groove shown in FIG.

Explanation of symbols

1 Sanitary napkin (absorbent article)
2 Top sheet 3 Back sheet 4 Absorber 6 Embossed groove

Claims (2)

A pattern of embossed grooves for absorbent articles having a liquid-permeable top sheet, a back sheet, and a liquid-retaining absorbent interposed between both sheets can be clearly formed in the embossed groove forming step. It is a method for evaluating the formability of an embossed groove to determine whether or not
On the pattern of the embossed grooves to be evaluated, assuming a band-like region having a constant width that crosses the absorbent article in the width direction, the position of the band-like region is moved by a certain distance in the longitudinal direction of the absorbent article. , At each position, find the total area of the embossed portion present in the belt-like region,
Method for evaluating formability of embossed groove for determining whether or not the embossed groove can be clearly formed on the basis of whether or not the maximum value of the total area of the embossed part is a certain value or less . The method for evaluating formability of an embossed groove according to claim 1, wherein the width of the belt-like region is 3 mm, and the belt-like region is moved by 1 mm in the longitudinal direction of the absorbent article to obtain the total area of the embossed portion.

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