JP7090542B2 - Absorbent article - Google Patents

Description

The present invention relates to an absorbent article.

Absorbent articles are known that include an adhesive for attaching the absorbent article to underwear. For example, in Patent Document 1, an absorber is interposed between the liquid-permeable front sheet and the impermeable back sheet, and an adhesive layer (adhesive) for preventing slippage by a hot melt adhesive is provided on the outer surface side. Provided insertable disposable absorbent articles are disclosed. In this absorbent article, for example, a hot melt adhesive having a viscosity of 5000 to 10000 cps when heated at 140 ° C. is used to prevent slippage on the outer surface of the non-woven fabric arranged on the outer surface side of the impermeable back sheet. An adhesive layer is formed. According to Patent Document 1, the reasons for the upper limit value and the lower limit value of the above viscosity range are as follows. When the viscosity at heating at 140 ° C. is less than 5000 cps, the hot melt adhesive often penetrates into the non-woven fabric, and a large amount of hot melt adhesive is required to obtain a desired adhesive force. On the other hand, when the viscosity when heated at 140 ° C. exceeds 10000 cps, the hot melt adhesive does not penetrate into the inside of the non-woven fabric and remains on the surface of the non-woven fabric, and adheres to the underwear when the absorbent article after use is removed. Become.

Japanese Unexamined Patent Publication No. 2002-355266

According to Patent Document 1, by applying a pressure-sensitive adhesive (hot melt adhesive) having a viscosity at around 140 ° C. to a non-woven fabric, an appropriate impregnation of the pressure-sensitive adhesive into the non-woven fabric can be obtained. To. However, when the inventor of the present invention conducted a test on a pressure-sensitive adhesive having a viscosity within the above viscosity range, the following results were found. However, in the test, an adhesive having a viscosity of 5300 cps at 140 ° C. is applied to a non-woven fabric located on the outer surface side of the back sheet of the absorbent article, the absorbent article is attached to the underwear, and the adhesive is attached to the underwear. This is a test in which the absorbent article is peeled off from the underwear. As a result of the test, it was found that when the absorbent article was peeled off from the underwear, the phenomenon that the adhesive remained on the underwear, that is, the phenomenon of adhesive residue occurred. According to the examination of the inventor of this case, the reason is considered as follows. When the melted pressure-sensitive adhesive is applied to the nonwoven fabric, it immediately begins to cool and becomes a pressure-sensitive adhesive at about 110 to 100 ° C. on the nonwoven fabric. Therefore, the temperature at the time of impregnation of the pressure-sensitive adhesive becomes low, the viscosity of the pressure-sensitive adhesive is lowered too much, and even if the pressure-sensitive adhesive tries to impregnate the inside of the nonwoven fabric thereafter, it cannot be sufficiently impregnated. Therefore, the adhesive enters between the constituent fibers of the non-woven fabric like the root of a tree and hardens, resulting in a lack of an anchor effect that makes it difficult to peel off. As a result, when the absorbent article is peeled off from the underwear, the bonding force between the adhesive and the non-woven fabric is defeated by the bonding force between the underwear and the adhesive, and the adhesive is peeled off from the non-woven fabric (absorbent article). It is thought that it remained in.

As described above, according to the study of the inventor of the present invention, even if the adhesive is adjusted based on the characteristics of the high temperature region as in Patent Document 1, the adhesive applied on the non-woven fabric of the actual absorbent article. It is difficult to determine whether the adhesive can be used effectively without verifying how it is impregnated in the non-woven fabric. For example, as described above, when the pressure-sensitive adhesive of Patent Document 1 is actually applied onto a non-woven fabric, it cannot be sufficiently impregnated into the non-woven fabric, resulting in adhesive residue. There is room for further improvement in the pressure-sensitive adhesive in order to stably impregnate the non-woven fabric with the pressure-sensitive adhesive and obtain a pressure-sensitive adhesive that does not leave adhesive residue.

An object of the present invention is to provide an absorbent article having an adhesive that can stably adhere to underwear when the absorbent article is attached and that does not easily remain on the underwear (glue residue is unlikely to occur) when the absorbent article is peeled off. It is in.

The absorbent article of the present invention is an absorbent article containing (1) a nonwoven fabric arranged on the non-skin side and an adhesive for fixing clothes applied to the surface of the nonwoven fabric on the non-skin side. The pressure-sensitive adhesive contains an impregnated portion impregnated in the nonwoven fabric, the ratio of the thickness of the impregnated portion to the thickness of the pressure-sensitive adhesive is 30 to 80%, and the storage elastic modulus of the pressure-sensitive adhesive is , 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 50 ° C., an absorbent article.

In this absorbent article, the ratio of the thickness of the impregnated portion to the thickness of the pressure-sensitive adhesive (hereinafter, also referred to as “impregnation rate”) is 30% or more. Therefore, in the impregnated portion, the adhesive can be appropriately diffused and permeated between the constituent fibers of the non-woven fabric. That is, the constituent fibers and the adhesive can be entangled to enhance the anchoring effect of the impregnated portion on the nonwoven fabric. Thereby, when the absorbent article is peeled off from the underwear, it is possible to prevent the adhesive from peeling off from the surface of the nonwoven fabric or the surface portion of the nonwoven fabric from peeling off from the nonwoven fabric together with the adhesive. That is, the adhesive residue can be suppressed. At the same time, since the impregnation rate is 80% or less, the thickness of the portion of the pressure-sensitive adhesive excluding the impregnated portion, that is, the portion of the pressure-sensitive adhesive on the surface of the nonwoven fabric can be made appropriate. Therefore, it is possible to prevent the bonding force from becoming too low due to the lack of the portion of the adhesive that contributes to adhesion to the underwear.
Here, in this absorbent article, the storage elastic modulus of the pressure-sensitive adhesive is further defined. However, the storage elastic modulus indicates how much energy due to the load applied to the adhesive is stored without being dissipated, and indicates the ratio of retaining elastic properties in the cross-sectional direction perpendicular to the load (its value). Is measured, for example, by applying a load to the adhesive with a leometer). The lower the storage elastic modulus of the pressure-sensitive adhesive, the more difficult it is to retain the elastic property, and the higher the storage elastic modulus, the easier it is to retain the elastic property. Therefore, if the storage elastic modulus is too low, the elastic properties of the pressure-sensitive adhesive may be too low, and the shearing force between the absorbent article and the garment may cause the pressure-sensitive adhesive to tear. On the other hand, if the storage elastic modulus is too high, the elastic properties of the pressure-sensitive adhesive may be too high, the stickiness of the pressure-sensitive adhesive may be lowered, and the absorbent article may not be fixed to the clothes.
Therefore, in this absorbent article, the storage elastic modulus of the pressure-sensitive adhesive is set to 1.0 × 10 ⁴ to 2 at 50 ° C., which is a temperature range (typical value) that can be assumed when the absorbent article is stored. It is set to 0.0 × 10 ⁵ Pa. As a result, since the storage elastic modulus is not too low, the shape of the adhesive can be stably maintained, and since the storage elastic modulus is not too high, an appropriate adhesive force is given to the nonwoven fabric to make the adhesive a non-woven fabric. Can be stably adhered to.
As described above, it is possible to provide an absorbent article having an adhesive that can stably adhere to the underwear when the absorbent article is attached and that does not easily remain in the underwear (glue residue is unlikely to occur) when the absorbent article is peeled off.

The absorbent article of the present invention may be (2) the absorbent article according to (1) above, wherein the tan δ of the pressure-sensitive adhesive is 1.0 to 5.0 at 80 ° C.
In this absorbent article, tan δ, which is a value obtained by dividing the loss elastic modulus of the pressure-sensitive adhesive by the storage elastic modulus of the pressure-sensitive adhesive, is defined. However, tan δ is the ratio of the loss elastic modulus, which is a guideline for the amount of energy dissipated by the load applied to the adhesive, and the storage elastic modulus, which is a guideline for the amount of energy stored without being dissipated. These values are measured, for example, by applying a load to the adhesive with a leometer). tan δ indicates whether the pressure-sensitive adhesive has a strong viscous property or a strong elastic property. The larger the tan δ, the more viscous the adhesive and the easier it is to impregnate the nonwoven fabric, and the smaller the tan δ, the more elastic the adhesive and the more difficult it is to impregnate the nonwoven fabric. Therefore, if tan δ is too small, it may be difficult for the adhesive to impregnate the non-woven fabric immediately after it is applied. If the tan δ is too large, the adhesive may impregnate the non-woven fabric too much immediately after it is applied.
Therefore, in this absorbent article, the tan δ is set to 1.0 to 5.0 at 80 ° C., which is the temperature (typical value) when the pressure-sensitive adhesive applied on the nonwoven fabric impregnates the nonwoven fabric. .. Since the tan δ is neither too small nor too large, the non-woven fabric can be appropriately impregnated with the adhesive. Thereby, the anchor effect of the impregnated portion on the non-woven fabric can be further enhanced.

In the absorbent article of the present invention, (3) the tan δ of the pressure-sensitive adhesive is 0.20 to 0.90 at 40 ° C., and the storage elastic modulus of the pressure-sensitive adhesive is 2.0 × 10 at 40 ° C. The absorbent article according to (1) or (2) above, which is ⁴ to 2.0 × 10 ⁵ Pa, may be used.
In this absorbent article, the tan δ and the storage elastic modulus are kept within the above numerical ranges at 40 ° C., which is (a representative value of) a temperature range that can be assumed when the absorbent article is used. Therefore, the pressure-sensitive adhesive can be in a state in which the viscous property and the elastic property are balanced. As a result, it is possible to almost stop the impregnation of the adhesive into the non-woven fabric when the absorbent article is stored after manufacturing, and when the absorbent article is used, the adhesive is used to stably attach the absorbent article to the clothes. Can stick to.

In the absorbent article of the present invention, (4) the tan δ of the pressure-sensitive adhesive is 0.8 to 4.0 at 75 ° C., and the storage elastic modulus of the pressure-sensitive adhesive is 1.0 × 10 at 75 ° C. The absorbent article according to any one of (1) to (3) above, which is ³ to 2.0 × 10 ⁴ Pa, may be used.
In this absorbent article, 75 ° C., which is the temperature (typical value) when the pressure-sensitive adhesive applied on the non-woven fabric impregnates the inside of the non-woven fabric and the temperature of the pressure-sensitive adhesive tends to decrease relatively easily. In, tan δ and the storage elastic modulus are set in the above numerical range. Therefore, the pressure-sensitive adhesive can be maintained at an appropriate hardness, diffusion of the nonwoven fabric in the in-plane direction can be suppressed, and impregnation can proceed in the thickness direction of the nonwoven fabric. Thereby, the effect of appropriately impregnating the non-woven fabric with the pressure-sensitive adhesive can be further enhanced. As a result, the impregnation rate of the pressure-sensitive adhesive can be set within the above-mentioned predetermined numerical range.

The absorbent article of the present invention is the absorbent article according to any one of (1) to (4) above, wherein (5) the amount of the adhesive applied to the nonwoven fabric is 20 to 200 g / m ² . , But it may be.
In this absorbent article, the amount of the pressure-sensitive adhesive applied to the non-woven fabric is within the above numerical range, which is a more appropriate amount. Therefore, an appropriate amount of the pressure-sensitive adhesive can be impregnated into the nonwoven fabric, whereby the anchoring effect of the impregnated portion on the nonwoven fabric can be enhanced. In addition, an appropriate amount of the pressure-sensitive adhesive can be left on the surface of the nonwoven fabric, thereby increasing the stickiness of the impregnated portion. As a result, when the absorbent article is attached to the underwear, the absorbent article can be stably adhered to the underwear, and when the absorbent article is peeled from the underwear, the adhesive is peeled from the surface of the non-woven fabric, etc. Can be suppressed.
If the coating amount is less than 20 g / m ² , when the adhesive is impregnated into the nonwoven fabric, the amount of the adhesive remaining on the surface of the nonwoven fabric is reduced, and sufficient adhesive strength may not be obtained. If the coating amount exceeds 200 g / m ² , the thickness of the adhesive exposed on the surface of the non-woven fabric becomes large, so that the adhesive may be torn off in the middle and adhere to the underwear.

The absorbent article of the present invention comprises (6) the nonwoven fabric includes a low density layer having a low fiber density and a high density layer having a high fiber density in the thickness direction, and at least a part of the impregnated portion is contained. The absorbent article according to any one of (1) to (5) above, which impregnates the high-density layer from the surface of the nonwoven fabric.
In this absorbent article, at least a part of the impregnated portion is impregnated up to a high-density layer of the non-woven fabric. Therefore, in the impregnated portion, the pressure-sensitive adhesive can be more diffused and more permeated between the constituent fibers of the non-woven fabric due to the capillary phenomenon. That is, the constituent fibers and the pressure-sensitive adhesive can be entangled to further enhance the anchoring effect of the impregnated portion on the non-woven fabric. Therefore, when the absorbent article is peeled off from the underwear, it is possible to prevent the adhesive from peeling off from the surface of the non-woven fabric.

The absorbent article of the present invention has (7) the absorbent article having a squeezed portion, and at least a part of the impregnated portion overlaps with the squeezed portion in a plan view, according to the above (1) to (6). The absorbent article according to any one of the items may be used.
In this absorbent article, at least a part of the impregnated part overlaps with the pressed part, that is, the part having a high fiber density. Therefore, the constituent fibers and the pressure-sensitive adhesive can be entangled to further diffuse the pressure-sensitive adhesive between the constituent fibers of the non-woven fabric in the impregnated portion and allow the pressure-sensitive adhesive to penetrate more. That is, the anchor effect on the non-woven fabric can be further enhanced. Therefore, when the absorbent article is peeled off from the underwear, it is possible to prevent the adhesive from peeling off from the surface of the non-woven fabric.

The absorbent article of the present invention is (8) arranged on the non-skin side of the adhesive, further provided with a protective sheet for protecting the adhesive, and the peel strength between the protective sheet and the adhesive is high. The absorbent article according to any one of (1) to (7) above, which is smaller than the peel strength between the pressure-sensitive adhesive and the non-woven fabric.
In this absorbent article, the peel strength between the protective sheet (eg, a release sheet or an individual packaging sheet) and the pressure-sensitive adhesive is smaller than the peel strength between the pressure-sensitive adhesive and the non-woven fabric. Therefore, when the absorbent article is peeled off from the protective sheet, the protective sheet can be peeled off from the pressure-sensitive adhesive without the pressure-sensitive adhesive peeling off from the non-woven fabric. Thereby, it is possible to prevent the pressure-sensitive adhesive from peeling off from the surface of the non-woven fabric.

In the absorbent article of the present invention, (9) the absorbent article has a fold line, and the thickness of the impregnated portion at a position overlapping the fold line in the thickness direction is the thickness of the fold line. The absorbent article according to any one of (1) to (8) above, which is larger than the thickness of the impregnated portion at a position where it does not overlap in the direction.
In this absorbent article, the thickness of the portion of the impregnated portion that overlaps the fold line in the thickness direction, that is, the overlapped portion of the fold line is relatively large. That is, in the folded line overlapping portion, a portion in which the pressure-sensitive adhesive is more diffused and more penetrated is formed between the constituent fibers of the non-woven fabric. Therefore, the constituent fibers and the adhesive can be entangled to further improve the anchoring effect on the nonwoven fabric at the folded line overlapping portion, and the folded line overlapping portion can be made difficult to peel off from the nonwoven fabric. At the same time, it is possible to make it difficult to peel off not only the folded line overlapping portion but also the peripheral portion connected to the folded line overlapping portion from the non-woven fabric. Therefore, when the absorbent article is peeled off from the underwear, it is possible to prevent the adhesive from peeling off from the surface of the non-woven fabric.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an absorbent article having an adhesive that can be stably adhered to underwear when the absorbent article is attached and that does not easily remain in the underwear (glue residue is unlikely to occur) when the absorbent article is peeled off. Will be.

It is a top view which shows the individual package body of the sanitary napkin which concerns on embodiment. It is a back view which shows the individual package body of the sanitary napkin which concerns on embodiment. It is sectional drawing along the AA line in FIG. It is an enlarged sectional view of the X part in FIG. It is a graph which shows the viscosity curve of a pressure-sensitive adhesive. It is a graph which shows the storage elastic modulus of a pressure-sensitive adhesive. It is a graph which shows the tan δ of a pressure-sensitive adhesive.

Hereinafter, the absorbent article according to this embodiment will be described by taking a sanitary napkin as an example. However, the absorbent article of the present invention is not limited to the example, and can be applied to various absorbent articles as long as it does not deviate from the gist of the present invention. Absorbent articles include, for example, panty liners, light incontinence pads, disposable diapers.

First, the configuration of the sanitary napkin 10 according to the present embodiment will be described. 1 and 2 are a plan view and a rear view showing a state in which the individual package 100 including the menstrual napkin 10 according to the embodiment is unfolded. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 4 is an enlarged cross-sectional view of the X portion in FIG. The individual package 100 is composed of a menstrual napkin 10 and a packaging sheet 30, and the menstrual napkin 10 is removably fixed to a substantially rectangular packaging sheet 30. The menstrual napkin 10 has a longitudinal direction L, a width direction W, and a thickness direction T that are orthogonal to each other. In FIGS. 1 and 2, the upper and upper sides of the menstrual napkin 10 are the front and front sides (F) of the menstrual napkin 10 (longitudinal direction L), and the lower and lower sides of the sanitary napkin 10 are the (longitudinal) of the menstrual napkin 10. (B) posterior and posterior (B) in direction L. The menstrual napkin 10 is provided with a pair of flap portions extending outward in the width direction W at a portion slightly forward from the center of the longitudinal direction L. Further in the present embodiment, the sanitary napkin 10 is further provided with a pair of hip flap portions extending outward in the width direction W in the rear portion in the longitudinal direction L. The menstrual napkin 10 has a longitudinal axis CL (virtual line) that passes through the center of the width direction W and extends in the longitudinal direction L, and a width axis CW (virtual line) that passes through the center of the flap portion in the longitudinal direction L and extends in the width direction W. ). The direction and side toward the longitudinal axis CL are the inward and inside of the width direction W, and the direction and side away from it are the outward and outside of the width direction W. The direction and side toward the width axis CW are the inward and inside of the longitudinal direction L, and the direction and side away from it are the outward and outside of the longitudinal direction L. Looking at the sanitary napkin 10 placed on a plane including the longitudinal direction L and the width direction W from above the thickness direction T is called "planar view", and the shape grasped in the plan view is called "planar shape". .. The "skin side" and "non-skin side" mean the side relatively close to the wearer's skin surface and the side far from the skin surface in the thickness direction T when the menstrual pad 10 is worn. These definitions are commonly used for each material of the menstrual pad 10 and the packaging sheet 30.

In the present embodiment, the sanitary napkin 10 has a liquid-permeable front sheet 11, a liquid-impermeable back sheet 13, and a liquid-absorbing and liquid-retaining substance arranged between the front sheet 11 and the back sheet 13. It comprises a sex absorber 12. The front sheet 11 constitutes the skin-side surface of the menstrual napkin 10, and the back sheet 13 constitutes the non-skin-side surface of the menstrual napkin 10. The absorber 12 includes an absorbent core and a core wrap covering it. The non-skin side surface of the front surface sheet 11 and the skin side surface of the absorber 12 are bonded with an adhesive or the like, and the non-skin side surface of the absorber 12 and the skin side surface of the back surface sheet 13 are bonded with an adhesive or the like. It is joined with. The peripheral portion of the non-skin side surface of the front surface sheet 11 (including the flap portion and the hip flap portion) and the peripheral portion of the skin side surface of the back surface sheet 13 (including the flap portion and the hip flap portion) are bonded with an adhesive. Will be done. In another embodiment, the absorber 12 does not include a core wrap. In yet another embodiment, a plurality of absorbers are laminated as the absorber 12. In yet another embodiment, the sanitary napkin 10 further includes a cover sheet (not shown) covering the back sheet 13 on the non-skin side of the back sheet 13, and the cover sheet constitutes the surface on the non-skin side. .. However, the sheet (eg, back sheet 13 or cover sheet) constituting the non-skin side surface of the menstrual napkin 10 is formed of a non-woven fabric. Therefore, in this embodiment, the back sheet 13 is made of a non-woven fabric. In another embodiment, when the cover sheet constitutes the non-skin side surface of the sanitary napkin 10, the cover sheet is formed of a non-woven fabric and the back sheet 13 is formed of a non-woven fabric or a sheet other than the non-woven fabric.

In the present embodiment, the sanitary napkin 10 includes a squeezing portion 14 in a region where the surface sheet 11 overlaps the absorber 12 in the thickness direction T. The squeezed portion 14 is formed in a region that abuts on the wearer's excretion opening at the time of wearing, that is, on both sides of the width direction W of the excretion opening contact area and on the rear side in the longitudinal direction L thereof. The squeezed portion 14 is formed by squeezing the surface sheet 11 and the absorber 12 from the skin side to the non-skin side. Therefore, the pressing portion 14 has a shape in which the surface sheet 11 and the absorber 12 are recessed from the surface sheet 11 side toward the absorber 12, and at least the surface sheet 11 and the absorber 12 are joined to each other. However, the position, shape, and number of the squeezed portions 14 are arbitrary. In another embodiment, the squeezed portion 14 does not include the surface sheet 11.

In this embodiment, the sanitary napkin 10 includes a plurality of pressure-sensitive adhesives 40, 50. The plurality of pressure-sensitive adhesives 40 and 50 are applied to the surface on the non-skin side of the back sheet 13 (nonwoven fabric) constituting the surface on the non-skin side. The plurality of adhesives 40 are for fixing clothes (underwear), and the menstrual napkin 10 is fixed to the skin side of the clothes (underwear). The plurality of pressure-sensitive adhesives 40 extend intermittently or continuously along the longitudinal direction L at the central portion of the menstrual pad 10 in the width direction W, and are arranged at predetermined intervals in the width direction W. The plurality of adhesives 50 are for fixing clothes (underwear), and fix a pair of flap portions to the non-skin side of the clothes (underwear) and a pair of hip flap portions to the skin side of the clothes (underwear). The plurality of pressure-sensitive adhesives 50 extend intermittently or continuously along the longitudinal direction L in each of the pair of flap portions and each of the pair of hip flap portions, and are arranged at predetermined intervals in the width direction W. However, the patterns of the plurality of adhesives 40 and 50 are arbitrary. At least a portion of the pressure-sensitive adhesive 40 overlaps the squeezed portion 14 in plan view. In another embodiment, the plurality of pressure-sensitive adhesives 40, 50 are applied to the non-skin side surface of the cover sheet (nonwoven fabric) constituting the non-skin side surface of the sanitary napkin 10.

In the present embodiment, the side of the plurality of adhesives 40 opposite to the back surface sheet 13 (or cover sheet) is covered with the release sheet 20 (protective sheet). The release sheet 20 is fixed to the packaging sheet 30 with a plurality of adhesives 60. Therefore, the menstrual napkin 10 is fixed to the packaging sheet 30 via a plurality of pressure-sensitive adhesives 40, a release sheet 20, and a plurality of pressure-sensitive adhesives 60. The peel strength between the release sheet 20 (protective sheet) and the pressure-sensitive adhesive 40 is smaller than the peel strength between the pressure-sensitive adhesive 40 and the back surface sheet 13 (nonwoven fabric). That is, the peel strength between the adhesive 40 and the back sheet 13 (nonwoven fabric) is relatively strong. In another embodiment, the side of the plurality of adhesives 40 opposite to the back sheet 13 (or cover sheet) is covered with the packaging sheet 30 (protective sheet).

In the present embodiment, when the sanitary napkin 10 is an individual package 100 individually wrapped by the packaging sheet 30, the sanitary napkin 10 and the packaging sheet 30 are folded by the following method. However, in the state of FIG. 1, the individual package 100 has a pair of longitudinal folding lines (not shown) extending along the longitudinal direction L, passing slightly outside the both end edges of the absorber 4 in the width direction W. The menstrual pad 10 is substantially divided into four equal parts in the longitudinal direction L, extends along the width direction W, and has a plurality of widthwise folding lines L1, L2, and L3 arranged at intervals in the longitudinal direction L. Then, as a folding method, first, in a state where the menstrual pad 10 is fixed to the packaging sheet 30 (FIG. 1), at the position of a pair of longitudinal folding lines (not shown), the width direction W of only the menstrual pad 10 is W. Both ends of the are folded onto the surface sheet 11. Next, separate release sheets (not shown) are placed on the adhesive 50 of the pair of flaps and on the adhesive 50 of the pair of hip flaps. Next, at the position of the widthwise folding line L3, the rear end portion of the packaging sheet 30 and the sanitary napkin 10 in the longitudinal direction L is folded onto the surface sheet 11. Next, at the position of the widthwise folding line L2, the partially folded packaging sheet 30 and the rear portion of the sanitary napkin 10 in the longitudinal direction L are folded onto the surface sheet 11. Next, at the position of the widthwise folding line L1, the rear portion of the further folded packaging sheet 30 and the menstrual pad 10 in the longitudinal direction L is folded onto the surface sheet 11. Next, the tab 35 arranged on the front edge of the packaging sheet 30 in the longitudinal direction L is attached to the folded packaging sheet 30. As described above, the menstrual napkin 10 is individually wrapped with the packaging sheet 30 to form the individual package 100.

In the present embodiment, the pressure-sensitive adhesive 40 includes an impregnated portion 45 impregnated in the non-woven fabric of the back surface sheet 13, and an exposed portion 41 which is a portion other than the impregnated portion 45 in the pressure-sensitive adhesive 40. The exposed portion 41 can also be said to be a portion exposed on the non-skin side surface of the non-woven fabric of the back sheet 13. Although not shown, the pressure-sensitive adhesive 50 also includes an impregnated portion impregnated in the non-woven fabric of the back surface sheet 13 and an exposed portion other than the impregnated portion in the pressure-sensitive adhesive 50, as in the case of the pressure-sensitive adhesive 40. As another embodiment, when the non-skin side surface of the sanitary napkin 10 is formed of a cover sheet, the impregnated portion 45 is impregnated into the non-woven fabric of the cover sheet, and the exposed portion 41 is the non-skin side of the cover sheet. It is exposed on the surface.

Here, as shown in FIG. 4, the thickness of the pressure-sensitive adhesive 40 (dimension in the thickness direction T) is D40, the thickness of the impregnated portion 45 (dimension in the thickness direction T) is D45, and the exposed portion 41. The thickness (dimension in the thickness direction T) is D41 (D41 = D40-D45). In that case, the ratio of the thickness D45 of the impregnating portion 45 to the thickness D40 of the pressure-sensitive adhesive 40 is 30 to 80%, preferably 40 to 70%. Therefore, the pressure-sensitive adhesive 40 can appropriately diffuse and permeate the pressure-sensitive adhesive between the constituent fibers of the back surface sheet 13 (nonwoven fabric) in the impregnated portion. That is, the constituent fibers of the back surface sheet 13 and the pressure-sensitive adhesive 40 can be entangled to enhance the anchoring effect of the impregnated portion 45 on the back surface sheet 13. On the other hand, the ratio of the thickness D41 of the exposed portion 41 to the thickness D40 of the pressure-sensitive adhesive 40 is 20 to 70%, preferably 30 to 60%. If the ratio of the thickness D41 of the exposed portion 41 is too low, the adhesive force is lowered and it becomes difficult to bond with the underwear, and if it is too high, it is too thick and the shearing force between the underwear and the back surface sheet 13 makes it easy to tear. Therefore, the pressure-sensitive adhesive 40 can secure an appropriate thickness that can adhere to other members in the exposed portion 41.

In the present embodiment, the thickness of the back surface sheet 13 (dimension in the thickness direction T) is D13. In that case, the ratio of the thickness D45 of the impregnated portion 45 to the thickness D13 of the back surface sheet 13 is, for example, 30 to 100%, preferably 50 to 100%. Therefore, the impregnated portion 45 is deeply impregnated in the back surface sheet 13 (nonwoven fabric). Therefore, even if the pressure-sensitive adhesive 40 adheres to another member and is pulled, the front surface portion of the back surface sheet 13 can be prevented from peeling off and separating from the back surface sheet 13 together with the pressure-sensitive adhesive 40. If the ratio of the thickness D45 of the impregnated portion 45 is too low, the anchoring effect of the adhesive 40 on the back surface sheet 13 is lowered.

In the present embodiment, the adhesive 40 is folded together with the back sheet 13 by folding the menstrual napkin 10 at each position of the plurality of widthwise folding lines L1, L2, and L3, so that the adhesive 40 is a back sheet. It becomes easier to penetrate into the inside of 13. Therefore, at the positions of the folded lines in each width direction, a recessed portion 51 in which the exposed portion 41 of the adhesive 40 is recessed on the absorber 12 side is formed, and the folded line overlapping portion 52 in which the impregnated portion 45 is deeply impregnated on the absorber 12 side. Is formed. Here, in the impregnated portion 45, the thickness (dimension in the thickness direction T) of the folded line overlapping portion 52 is set to D52. In this case, the thickness D52 of the folded line overlapping portion 52 of the impregnated portion 45 is larger than the thickness D45 of the peripheral impregnated portion 45 that does not overlap with the widthwise folded line (D52> D45). Therefore, in the folded line overlapping portion 52, the adhesive can be more diffused between the constituent fibers of the back surface sheet 13 (nonwoven fabric) to form a more permeated portion. Therefore, the anchor effect of the impregnated portion 45 on the back surface sheet 13 can be further improved. Assuming that the thickness of the recessed portion 51 of the exposed portion 41 (dimension in the thickness direction T) is D51, the thickness D52 of the folding line overlapping portion 52 is preferably larger than the thickness D51 of the recessed portion 51. When the menstrual pad 10 is expanded from the individually wrapped state, wrinkles may be formed because the absorber 12 is present in the portion where the widthwise fold lines L1 to L3 are located. many. Therefore, it is difficult to join the menstrual napkin 10 to the underwear without wrinkles. Therefore, by making the thickness D51 of the recessed portion 51 in the exposed portion 41 relatively thin and reducing the joint strength of the recessed portion 51 which is easily torn by wrinkles, the recessed portion 51 is torn and adhesive residue is generated. Can be suppressed. In addition, by making the thickness D52 of the folded line overlapping portion 52 in the impregnated portion 45 relatively thick, the anchor effect of the impregnated portion 45 with respect to the back surface sheet 13 can be further improved.

In the present embodiment, as the material of the front surface sheet 11, the absorber 12, and the back surface sheet 13, known materials generally available for the menstrual napkin 10 can be used.

Examples of the material of the surface sheet 11 include a non-woven fabric, a woven fabric, a synthetic resin film having liquid permeation holes formed therein, and a composite sheet thereof. Examples of the constituent fibers of the non-woven fabric include natural fibers, regenerated fibers, inorganic fibers, synthetic resin fibers and the like. Examples of the non-woven fabric include air-through non-woven fabric, spunlace non-woven fabric, spunbond non-woven fabric, and point-bond non-woven fabric. Examples of the basis weight of the surface sheet 11 include 5 g / m ² to 100 g / m ² , and 20 g / m ² to 50 g / m ² is preferable. Examples of the thickness of the surface sheet 11 include 0.2 to 5 mm.

Examples of the material of the absorber 12 include water-absorbent fibers such as pulp fibers and synthetic fibers, and super absorbent polymers (SAP). As the basis weight of the water-absorbent fiber of the absorber 12, for example, 10 to 1000 g / m ² is mentioned, and 150 to 1000 g / m ² is preferable. Examples of the basis weight of the superabsorbent polymer include 5 to 500 g / m ² , and 10 to 400 g / m ² is preferable. The thickness of the absorber 4 is, for example, 1 to 50 mm, and is preferably 5 to 30 mm. When the absorbent body 4 includes the absorbent core and the core wrap, the material of the absorbent core includes the above-mentioned water-absorbent fiber and the superabsorbent polymer, and the material of the core wrap is a liquid-permeable material such as tissue. Examples include hydrophilic fibers. In another embodiment, the material of the absorbent core of the absorber 12 is 90% by mass or more, preferably 95% by mass or more, which is a super absorbent polymer (SAP).

Examples of the material of the back sheet 13 include a non-woven fabric which has been subjected to a hydrophobic treatment or a waterproof treatment and uses fibers, a non-woven fabric which has been subjected to a hydrophobic treatment or a waterproof treatment, a composite sheet of a non-woven fabric and a synthetic resin film, and the like. Examples of the constituent fibers of the non-woven fabric include natural fibers, regenerated fibers, synthetic resin fibers, and inorganic fibers. Examples of the non-woven fabric include SMS non-woven fabric, air-through non-woven fabric, spunlace non-woven fabric, spunbond non-woven fabric, and point-bond non-woven fabric. Examples of the basis weight of the back sheet 13 include 10 g / m ² to 500 g / m ² , and 20 g / m ² to 300 g / m ² is preferable. If the basis weight is too low, when the adhesive 40 is impregnated, if the strength of the back sheet 13 is weak, the adhesive 40 is peeled off together with the back sheet 13 by the shearing force between the underwear and the back sheet 13. There is a risk. If the basis weight is too high, when the pressure-sensitive adhesive 40 is impregnated, if the strength of the pressure-sensitive adhesive 40 is weak, the pressure-sensitive adhesive force 40 may be torn by the shearing force between the underwear and the back sheet. Examples of the thickness of the back sheet 13 include 0.2 to 5 mm. As another embodiment, when a cover sheet is used as a sheet constituting the non-skin side surface of the sanitary napkin 10, for example, the same material as the material of the back sheet 13 described above can be used as the material. .. In that case, a non-stretchable synthetic resin film may be used as the back sheet 13.

As the type of the non-woven fabric of the back sheet 13, SMS non-woven fabric and air-through non-woven fabric are preferable. In the SMS nonwoven fabric, in the thickness direction T, a spunbond layer which is a low density layer having a low fiber density, a melt blown layer which is a high density layer having a high fiber density, and a spunbond layer which is a low density layer having a low fiber density. , Are laminated in this order. Further, since one side of the air-through nonwoven fabric is conveyed while being in contact with the mesh-shaped belt at the time of manufacture, a high-density layer having a high fiber density is formed on the side of the one side, and the fiber is formed on the side of the other side. A low density layer is formed. In that case, at least a part of the impregnated portion 45 impregnates the high-density layer from the surface of such a non-woven fabric, so that the anchor effect of the impregnated portion 45 on the back surface sheet 13 can be enhanced.

As the adhesive for bonding between each material (example: front surface sheet 11, absorber 12, back surface sheet 13), a known material that can be used in the menstrual napkin 10 can be used, for example, a thermoplastic adhesive (example: hot). Melt adhesive). Further, as the material of the release sheet 20, a known material generally used in the sanitary napkin 10 can be used. For example, a material obtained by applying a silicone resin-based release material to a base material of paper or a resin sheet. Can be mentioned. Further, as the material of the packaging sheet 30, known materials generally used in the menstrual napkin 10 can be used, and examples thereof include synthetic resin films, paper, and non-woven fabrics.

In the present embodiment, the pressure-sensitive adhesive 40 contains an olefin-based base polymer as a main component and a rubber-based base polymer for performance adjustment. Specifically, the pressure-sensitive adhesive is an olefin-based base polymer (eg, preferably an ethylene, propene and / or butene-based poly-α-olefin, preferably an atactic poly-α-olefin (APAO), and , Ethylene / α-olefin and propylene / α-olefin copolymers, preferably polymers consisting of ethylene and propene, 1-butene, 1-hexene, 1-octene, or a combination thereof), and rubber-based. It is composed of a base polymer (example: SBS (styrene / butadiene / styrene) polymer, SIS (styrene / isoprene / styrene) polymer, etc.), tack fire, oil, wax and the like. In the pressure-sensitive adhesive, in order to increase the upper limit of the storage elastic modulus, for example, a rubber-based base polymer is relatively increased, or a monomer having a high molecular weight as a monomer used in the olefin-based base polymer is used. It is preferable to choose. In order to lower the lower limit of the storage elastic modulus, for example, it is preferable to relatively reduce the rubber-based base polymer or select a monomer having a low molecular weight as the monomer used in the olefin-based base polymer. The same applies preferably to the pressure-sensitive adhesive 50 (hereinafter, the same applies).

In the present embodiment, the pressure-sensitive adhesive 40 contains 30 to 80% by mass of an olefin-based base polymer, or the pressure-sensitive adhesive 40 contains 0 to 30% by mass of a rubber-based base polymer and 30 to 60% by mass of an olefin-based base polymer. %contains. In addition, the pressure-sensitive adhesive further contains a tack fire, an oil, and a wax. They are effective for proper application, that is, for stability of the physical properties (eg, viscosity, elasticity) of the adhesive in the adhesive storage tank, particularly for preventing oxidation and aging of the adhesive at high temperatures. .. Examples of the tack fire include (example: copolymers and terpolymers of terpenes, compatible resins such as polyterpene resins or mixtures thereof). Examples of the wax include olefin wax modified with carboxylic acid or carboxylic acid anhydride. Examples of the oil include paraffinic oil, naphthenic oil and aromatic oil. Examples of their mass ratio include 20 to 50% by mass with respect to the base polymer.

Examples of the method for producing the pressure-sensitive adhesive 40 include the following methods. When using an olefin-based base polymer and a rubber-based base polymer as the base polymer, first, the olefin-based base polymer is mixed with the rubber-based base polymer, and if necessary, the tack fire, oil, and wax are mixed, and then the mixture is further mixed. Various additives are added as needed. Then, the pressure-sensitive adhesive is manufactured by heating and mixing the agent containing each component while melting. Specifically, the pressure-sensitive adhesive can be produced by putting each of the above components into a melting and mixing kettle equipped with a stirrer and heating and mixing them.

In the present embodiment, the storage elastic modulus of the pressure-sensitive adhesive of the pressure-sensitive adhesive 40 has the following temperature characteristics. However, the storage elastic modulus indicates how much energy due to the load applied to the adhesive is stored without being dissipated, and indicates the ratio of retaining elastic properties in the cross-sectional direction perpendicular to the load (its value). Is measured by applying a load to the pressure-sensitive adhesive in a dynamic elastic modulus measuring device such as a leometer). The storage elastic modulus of the pressure-sensitive adhesive is 8.0 × 10 ² to 1.5 × 10 ⁴ Pa, preferably 9.0 × 10 ² to 1.0 × 10 ⁴ Pa, at 80 ° C. Further, the storage elastic modulus of the pressure-sensitive adhesive is 1.0 × 10 ³ to 2.0 × 10 ⁴ Pa, preferably 2.0 × 10 ³ to 2.0 × 10 ⁴ Pa at 75 ° C. .. It should be noted that 80 ° C. is the temperature (typical value or lower limit value) when the adhesive actually applied onto the non-woven fabric is impregnated into the non-woven fabric after being melted at a predetermined temperature (example: 100 to 110 ° C.). Can be thought of. Further, 75 ° C. is when the pressure-sensitive adhesive actually applied onto the non-woven fabric is impregnated into the non-woven fabric, which is melted at a predetermined temperature, and when the sanitary napkin 10 is transported at high speed, the pressure-sensitive adhesive is used. It can be considered as the temperature (typical value or lower limit value) when the temperature tends to decrease relatively easily. The storage elastic modulus of the pressure-sensitive adhesive is 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa, preferably 1.5 × 10 ⁴ to 1.0 × 10 ⁵ Pa, at 50 ° C. .. It should be noted that 50 ° C. can be considered as (a typical value) of a temperature range that can be assumed when the menstrual pad 10 is stored. The storage elastic modulus of the pressure-sensitive adhesive is 2.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa, preferably 3.0 × 10 ⁴ to 1.5 × 10 ⁵ Pa at 40 ° C. .. It should be noted that 40 ° C. can be considered as (a typical value) of a temperature range that can be assumed when using the sanitary napkin 10. That is, by controlling the menstrual napkin 10 at a temperature slightly higher than the body temperature, the menstrual napkin 10 can be made to withstand actual use. However, it is not necessary for all of the plurality of pressure-sensitive adhesives 40 to satisfy the above-mentioned properties, and it is sufficient that at least 80% of the plurality of pressure-sensitive adhesives 40 are filled with the pressure-sensitive adhesive 40, preferably 90% of the pressure-sensitive adhesive 40 is satisfied, and further. It is preferable that the pressure-sensitive adhesive 40 is filled with 95%. Preferably, the same applies to the plurality of pressure-sensitive adhesives 50.

In the present embodiment, the pressure-sensitive adhesive tan δ of the pressure-sensitive adhesive 40 has the following temperature characteristics. However, tan δ is the ratio of the loss elastic modulus, which is a guideline for the amount of energy dissipated by the load applied to the pressure-sensitive adhesive, and the storage elastic modulus, which is a guideline for the degree to which the energy is stored without being dissipated. These values are measured by applying a load to the pressure-sensitive adhesive in a dynamic viscoelasticity measuring device such as a leometer). The tan δ of the pressure-sensitive adhesive is 1.0 to 5.0, preferably 1.2 to 4.0 at 80 ° C. Further, the tan δ of the pressure-sensitive adhesive is 0.8 to 4.0, preferably 0.85 to 3.5 at 75 ° C. The tan δ of the pressure-sensitive adhesive is 0.2 to 1.0, preferably 0.25 to 0.95 at 50 ° C. The tan δ of the pressure-sensitive adhesive is 0.20 to 0.90, preferably 0.25 to 85, at 40 ° C. The meanings of 80 ° C, 75 ° C, 50 ° C, and 40 ° C are as described above. However, it is not necessary for all of the plurality of pressure-sensitive adhesives 40 to satisfy the above-mentioned properties, and it is sufficient that at least 80% of the plurality of pressure-sensitive adhesives 40 are filled with the pressure-sensitive adhesive 40, preferably 90% of the pressure-sensitive adhesive 40 is satisfied, and further. It is preferable that the pressure-sensitive adhesive 40 is filled with 95%. Preferably, the same applies to the plurality of pressure-sensitive adhesives 50.

In the present embodiment, the amount of the pressure-sensitive adhesive 40 applied to the back sheet 13 is, for example, 20 to 200 g / m ² . The coating amount is preferably 30 to 100 g / m ² . Therefore, an appropriate amount of the adhesive can be impregnated in the nonwoven fabric, and an appropriate amount of the adhesive can be left on the surface of the nonwoven fabric.

In the present embodiment, the peel strength of the pressure-sensitive adhesive (measured using a kanakin dough: described later) is, for example, 0.7 to 8 N / 25 mm, preferably 1 to 6 N / 25 mm. If the peel strength is less than 0.7 N / 25 mm, the adhesive 40 may peel off from the underwear while the menstrual napkin 10 is attached. On the other hand, when the peel strength exceeds 8 N / 25 mm, the adhesive 40 may be easily peeled from the underwear when the sanitary napkin 10 is removed.

The pressure-sensitive adhesive 40 of the present embodiment is not necessarily significantly affected by the value of the melt viscosity, but has, for example, the following tendencies. The melt viscosity at 120 ° C. is, for example, 3000 to 40,000 mPa · s, and is preferably 4000 to 10000 mPa · s. The pressure-sensitive adhesive 40 has a melt viscosity at 140 ° C. of, for example, 1000 to 20000 mPa · s, preferably 2000 to 5000 mPa · s. When a pressure-sensitive adhesive showing such a tendency is used, it becomes easy to impregnate an appropriate amount of the pressure-sensitive adhesive into the nonwoven fabric, and it becomes easy to leave an appropriate amount of the pressure-sensitive adhesive on the surface of the nonwoven fabric. If the melt viscosity is too low, the exposed portion of the nonwoven fabric cannot be formed to a sufficient thickness, and if it is too high, the impregnated portion cannot be formed to a sufficient thickness.

In the present embodiment, the menstrual napkin 10 (absorbent article) has the ratio of the thickness of the impregnated portion 45 to the thickness of the pressure-sensitive adhesive 40 (preferably containing the pressure-sensitive adhesive 50, the same applies hereinafter), that is, the impregnation rate. , 30-80%. The storage elastic modulus of the pressure-sensitive adhesive 40 is 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 50 ° C.
As described above, in the sanitary napkin 10, the impregnation rate is set to 30% or more. Therefore, in the impregnated portion 45, the adhesive 40 can be appropriately diffused and permeated between the constituent fibers of the back surface sheet 13 (or the cover sheet, the same applies hereinafter) which is a non-woven fabric. That is, the constituent fibers and the pressure-sensitive adhesive 40 can be entangled to enhance the anchoring effect of the impregnated portion 45 on the back surface sheet 13 (nonwoven fabric). As a result, when the sanitary napkin 10 is peeled off from the underwear, the adhesive 40 is peeled off from the front surface of the back surface sheet 13, or the front surface portion of the back surface sheet 13 is peeled off in layers and separated from the back surface sheet 13 together with the adhesive 40. It is possible to suppress such things. That is, the adhesive residue can be suppressed. At the same time, since the impregnation rate is 80% or less, the thickness of the exposed portion 41, which is the portion of the adhesive 40 excluding the impregnated portion 45, that is, the portion on the front surface of the back surface sheet 13 of the adhesive 40, is appropriate. You can do it. Therefore, it is possible to prevent the bonding force from becoming too low due to the lack of the portion of the pressure-sensitive adhesive 40 that contributes to adhesion to the underwear.
Here, the menstrual napkin 10 further defines the storage elastic modulus of the pressure-sensitive adhesive 40. However, the lower the storage elastic modulus of the pressure-sensitive adhesive 40, the more difficult it is to retain the elastic property, and the higher the storage elastic modulus, the easier it is to retain the elastic property. Therefore, if the storage elastic modulus is too low, the elastic properties of the pressure-sensitive adhesive 40 are too low, and the shearing force between the menstrual napkin 10 and the clothes may cause the pressure-sensitive adhesive 40 to be torn. On the other hand, if the storage elastic modulus is too high, the elastic property of the pressure-sensitive adhesive 40 is too high, the stickiness of the pressure-sensitive adhesive 40 is lowered, and the menstrual napkin 10 may not be fixed to the clothes. Therefore, in the sanitary napkin 10, the storage elastic modulus of the pressure-sensitive adhesive 40 is 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 50 ° C. As a result, since the storage elastic modulus is not too low, the shape of the adhesive 40 can be stably maintained, and since the storage elastic modulus is not too high, an appropriate adhesive force is imparted to the menstrual napkin 10. The pressure-sensitive adhesive 40 can be stably adhered to the menstrual napkin 10.
As described above, a pressure-sensitive adhesive that can stably adhere to underwear when the menstrual napkin 10 (absorbent article) is attached and does not remain on the underwear when the menstrual napkin 10 (absorbent article) is peeled off (no adhesive residue is generated). A sanitary napkin 10 (absorbent article) having the above can be provided.

In the present embodiment, as a preferred embodiment, the tan δ of the pressure-sensitive adhesive 40 is 1.0 to 5.0 at 80 ° C.
As described above, in the sanitary napkin 10 (absorbent article), the tan δ (loss elastic modulus / storage elastic modulus) of the pressure-sensitive adhesive 40 is defined. However, tan δ indicates whether the pressure-sensitive adhesive 40 has a strong viscous property or a strong elastic property. The larger the tan δ, the more viscous the adhesive 40 is, and the easier it is to impregnate the back sheet 13 (nonwoven fabric). The smaller the tan δ, the more elastic the adhesive 40 is, and the more difficult it is to impregnate the back sheet 13. Therefore, if the tan δ is too small, it may be difficult for the adhesive 40 to impregnate the back sheet 13 immediately after being applied. If the tan δ is too large, the adhesive 40 may impregnate the back sheet 13 too much immediately after being applied. Therefore, in the menstrual napkin 10, the tan δ is set to 1.0 to 4.0 at 80 ° C. Therefore, since the tan δ is neither too small nor too large, the adhesive 40 can be appropriately impregnated into the back sheet 13. As a result, the anchoring effect of the impregnated portion 45 on the back surface sheet 13 can be further enhanced.

As a preferred embodiment in the present embodiment, the tan δ of the pressure-sensitive adhesive 40 is 0.20 to 0.90 at 40 ° C., and the storage elastic modulus of the pressure-sensitive adhesive 40 is 2.0 × 10 ^4-2 at 40 ° C. It is 0.0 × 10 ⁵ Pa.
As described above, by keeping the tan δ and the storage elastic modulus within the above numerical ranges at 40 ° C., the pressure-sensitive adhesive 40 can be in a state in which the viscous property and the elastic property are balanced. As a result, the impregnation of the adhesive 40 into the back sheet 13 (nonwoven fabric) can be substantially stopped when the sanitary napkin 10 is stored after production. Further, when the menstrual napkin 10 is used, the adhesive 40 can stably adhere the menstrual napkin 10 to the clothes.

As a preferred embodiment in the present embodiment, the tan δ of the pressure-sensitive adhesive 40 is 0.8 to 4.0 at 75 ° C., and the storage elastic modulus of the pressure-sensitive adhesive 40 is 1.0 × 10 ³ to 2 at 75 ° C. It is 0.0 × 10 ⁴ Pa.
In this way, the tan δ and the storage elastic modulus are set within the above numerical ranges at 75 ° C., which is a stage in which the pressure-sensitive adhesive 40 actually applied on the back surface sheet 13 is in the process of impregnating the back surface sheet 13 (nonwoven fabric). Therefore, the pressure-sensitive adhesive 40 can be maintained at an appropriate hardness, diffusion of the back surface sheet 13 in the in-plane direction can be suppressed, and impregnation can proceed in the thickness direction T of the back surface sheet 13. Thereby, the effect of appropriately impregnating the back surface sheet 13 with the adhesive 40 can be further enhanced. As a result, the impregnation rate of the pressure-sensitive adhesive 40 can be set within the above-mentioned predetermined numerical range.

In the present embodiment, as a preferred embodiment, the amount of the pressure-sensitive adhesive 40 applied to the back sheet 13 (nonwoven fabric) is 20 to 200 g / m ² .
Therefore, an appropriate amount of the pressure-sensitive adhesive 40 can be impregnated into the back surface sheet 13, thereby enhancing the anchoring effect of the impregnated portion 45 on the back surface sheet 13. In addition, an appropriate amount of the pressure-sensitive adhesive 40 can be left on the surface of the back surface sheet 13, thereby increasing the stickiness of the impregnated portion 45. As a result, when the sanitary napkin 10 is attached to the underwear, the sanitary napkin 10 can be stably adhered to the underwear, and when the sanitary napkin 10 is peeled off from the underwear, the adhesive 40 is applied to the back sheet 13. It is possible to suppress peeling from the surface. If the coating amount is less than 20 g / m ² , when the pressure-sensitive adhesive 40 is impregnated into the back surface sheet 13, the amount of the pressure-sensitive adhesive 40 remaining on the front surface of the back surface sheet 13 may be reduced, and sufficient adhesive strength may not be obtained. be. If the coating amount exceeds 200 g / m ² , the thickness of the adhesive 40 exposed on the surface of the back surface sheet 13 becomes large, so that the adhesive 40 may be torn off in the middle and adhere to the underwear.

As a preferred embodiment in the present embodiment, the back surface sheet 13 (nonwoven fabric) includes a low density layer having a low fiber density and a high density layer having a high fiber density in the thickness direction T, and at least a part of the impregnated portion 45. Impregnates the high-density layer from the front surface of the back surface sheet 13. Examples of the high-density layer include a melt blown layer of the SMS nonwoven fabric and a layer of the air-through nonwoven fabric on the side in contact with the belt.
As described above, in the sanitary napkin 10 (absorbent article), at least a part of the impregnated portion 45 is impregnated up to the high-density layer of the back sheet 13. Therefore, in the impregnated portion 45, the pressure-sensitive adhesive 40 can be more diffused and more permeated between the constituent fibers of the back surface sheet 13 due to the capillary phenomenon. That is, the constituent fibers and the pressure-sensitive adhesive 40 can be entangled to further enhance the anchoring effect of the impregnated portion 45 on the back surface sheet 13. Therefore, when the sanitary napkin 10 is peeled off from the underwear, it is possible to prevent the pressure-sensitive adhesive 40 from peeling off from the front surface of the back sheet 13.

In the present embodiment, as a preferred embodiment, at least a part of the impregnated portion 45 overlaps with the squeezed portion 14 in a plan view. That is, at least a part of the impregnated portion 45 overlaps with the portion having a high fiber density. Therefore, the constituent fibers and the pressure-sensitive adhesive 40 can be entangled to further diffuse the pressure-sensitive adhesive 40 between the constituent fibers of the back surface sheet 13 (nonwoven fabric) in the impregnated portion 45 and allow the pressure-sensitive adhesive 40 to penetrate more. That is, the anchor effect on the back surface sheet 13 can be further enhanced. Therefore, when the sanitary napkin 10 (absorbent article) is peeled off from the underwear, it is possible to prevent the pressure-sensitive adhesive 40 from peeling off from the front surface of the back surface sheet 13.

In the present embodiment, as a preferred embodiment, a release sheet 20 as a protective sheet (however, when the adhesive 40 directly adheres to the packaging sheet 30 without using the release sheet 20, the packaging sheet 30 and the same applies hereinafter) and the adhesive. The peel strength between the adhesive 40 and the back sheet 13 (nonwoven fabric) is smaller than the peel strength between the pressure-sensitive adhesive 40 and the back sheet 13 (nonwoven fabric).
Therefore, when the sanitary napkin 10 (absorbent article) is peeled off from the release sheet 20, the release sheet 20 can be peeled off from the pressure-sensitive adhesive 40 without the pressure-sensitive adhesive 40 peeling off from the back surface sheet 13. As a result, it is possible to prevent the pressure-sensitive adhesive 40 from peeling off from the front surface of the back surface sheet 13.

In the present embodiment, as a preferred embodiment, the thickness D52 of the impregnating portion 45 at a position where it overlaps with at least one of the folding lines L1 to L3 in the thickness direction T does not overlap with the folding lines L1 to L3 in the thickness direction T. The thickness of the impregnated portion 45 in is larger than the thickness D45. That is, the thickness of the portion of the impregnated portion 45 that overlaps with at least one of the folded lines L1 to L3 in the thickness direction T, that is, the folded line overlapping portion 52 is relatively large. Therefore, in the folded line overlapping portion 52, the pressure-sensitive adhesive 40 is more diffused between the constituent fibers of the back surface sheet 13 (nonwoven fabric) to form a more permeated portion. Therefore, the constituent fibers and the adhesive 40 can be entangled to further improve the anchor effect of the folded line overlapping portion 52 on the back surface sheet 13, and the folded line overlapping portion 52 cannot be easily peeled off from the back surface sheet 13. can do. At the same time, it is possible to make it difficult to peel off not only the folded line overlapping portion 52 but also the peripheral portion connected to the folded line overlapping portion 52 from the back surface sheet 13. Therefore, when the sanitary napkin 10 (absorbent article) is peeled off from the underwear, it is possible to prevent the pressure-sensitive adhesive 40 from peeling off from the front surface of the back surface sheet 13.

Hereinafter, the present invention will be described in more detail by exemplifying Examples and Comparative Examples, but the present invention is not limited to such Examples.

1. 1. Samples (1) Samples of Examples 1 to 3 As the samples of Examples 1 to 3, the adhesive of the above embodiment was prepared. However, the details of each sample are as follows.
-Example 1 contains an olefin-based base polymer as a main component, and further contains a rubber-based base polymer.
-Example 2 contains an olefin-based base polymer as a main component, and further contains a rubber-based base polymer.
-Example 3 contains an olefin-based base polymer as a main component, and further contains a rubber-based base polymer.
However, the samples of Examples 1 to 3 differ from each other in the mass ratio and / or material of the olefin-based base polymer and the rubber-based base polymer.
(2) Samples of Comparative Examples 1 and 2 As the samples of Comparative Examples 1 and 2, a pressure-sensitive adhesive different from the pressure-sensitive adhesive of the above-described embodiment was prepared. However, the details of each sample are as follows.
-Comparative Example 1 contains a rubber-based base polymer as a main component, and further contains an olefin-based base polymer.
-Comparative Example 2 is a pressure-sensitive adhesive containing an olefin-based base polymer as a main component and does not contain a rubber-based base polymer.
However, the samples of Comparative Examples 1 and 2 have different mass ratios and / or materials of the olefin-based base polymer and the rubber-based base polymer as compared with the samples of Examples 1 to 3.
(3) Coating amount The samples (adhesives) of Examples 1 to 3 and Comparative Examples 1 and 2 were applied within the range of 20 to 200 g / m ² basis weight when applied to the non-woven fabric (back sheet). ..

(2) Evaluation method (2-1) Adhesive impregnation rate The adhesive impregnation rate was determined by the following procedure. First, the physiology of the above embodiment, in which the adhesives described in Examples 1 to 3 are applied to the non-skin surface side of the back sheet (spunbonded non-woven fabric, basis weight 20 g / m ² , thickness 1.5 mm) at 140 ° C. A napkin for use was prepared. Next, the back sheet (nonwoven fabric) impregnated with the adhesive was removed from the sanitary napkin and frozen in liquid nitrogen. Next, the frozen non-woven fabric was cut by applying a razor perpendicularly to the surface coated with the adhesive. Subsequently, a cross-sectional photograph of the non-woven fabric cut with a scanning electron microscope is taken to specify the thickness of the adhesive impregnated in the non-woven fabric, that is, the thickness of the impregnated portion and the thickness of the entire adhesive. did. The impregnation rate was calculated by (thickness of the adhesive impregnated in the non-woven fabric) / (thickness of the entire adhesive). When the surface of the non-woven fabric, the surface of the pressure-sensitive adhesive, or the boundary between the non-woven fabric and the pressure-sensitive adhesive has irregularities, the unevenness in the cross-sectional photograph is regarded as a roughness curve, and the average line thereof is used as the surface or the boundary. Then, the cross-sectional shape of the pressure-sensitive adhesive is assumed to be a rectangle having the length in the plane direction of the pressure-sensitive adhesive at the position of the surface of the nonwoven fabric in the cross-sectional photograph and having the cross-sectional area of the pressure-sensitive adhesive grasped by the cross-sectional photograph. .. Then, the thickness of the entire pressure-sensitive adhesive and the thickness of the pressure-sensitive adhesive impregnated in the nonwoven fabric were determined from the rectangle. The thickness of the exposed portion on the surface of the nonwoven fabric, that is, the thickness of the exposed portion (also referred to as "surface film thickness") is (the thickness of the entire adhesive)-(impregnated into the nonwoven fabric). The thickness of the adhesive used).
(2-2) Melt Viscosity of Adhesive The melt viscosity of the adhesive was measured by JAI 7-1991, Method B. Specifically, a Brookfield RVT type viscometer (Analog Viscometer RVT115 manufactured by Brooksfield Co., Ltd.) was used, and the No. 27 rotor was used.
(2-3) Storage elastic modulus G', loss elastic modulus G', tan δ of adhesive
The storage elastic modulus G', loss elastic modulus G', and tan δ of the adhesive were measured according to JIS K 6394. In this embodiment, a dynamic elastic modulus measuring device (manufactured by IT Measurement Control Co., Ltd., DVA-200) was measured. The test temperature was 0 to 120 ° C., the temperature rising condition was 5 ° C./min, the deformation method was shearing, and the frequency was 10 Hz.
(2-4) Adhesive residue test (use test)
The adhesive residue test was performed according to the following procedure. First, the physiology of the above embodiment, in which the adhesives described in Examples 1 to 3 are applied to the non-skin surface side of the back sheet (spunbonded non-woven fabric, basis weight 20 g / m ² , thickness 1.5 mm) at 140 ° C. A napkin for use was prepared. Two types of adhesive basis weight were prepared. The product length of this menstrual napkin is 420 mm, and the product width is 160 mm including a pair of flaps. Next, 10 users were actually asked to wear the menstrual napkin for 8 hours from 22:00 pm to 6:00 am, and after use, the menstrual napkin was peeled off from the underwear, and the phenomenon that the adhesive remained on the underwear occurred. I investigated the probability. In Table 1 below, it is shown as {(number of occurrences of adhesive residue) / 10 (person)} × 100 (%).
(2-5) Peeling strength of the pressure-sensitive adhesive The peeling strength of the pressure-sensitive adhesive was measured by the following procedure. First, the same non-woven fabric as the back sheet was impregnated with an adhesive at the same temperature as when the sanitary napkin was manufactured. Next, the non-woven fabric coated with the adhesive and the coated fabric for JIS L0803 conformity test (Kanakin No. 3) are left for 30 minutes in an atmosphere at a temperature of 40 ° C. and a humidity of 60%. Next, the non-woven fabric and the kanakin cloth were bonded together. Subsequently, the laminated body of the laminated non-woven fabric and the kanakin dough was left at a pressure of 25 g / cm ² for 30 minutes in an atmosphere of a temperature of 40 ° C. and a humidity of 60%. After that, using a tensile tester (AG-1kNI manufactured by Shimadzu Corporation), one chuck holds the longitudinal end of the non-woven fabric, and the other chuck sandwiches the longitudinal end of the kanakin dough. Then, the distance between the chucks at the start of peeling was set to 20 mm, the tensile (peeling) speed was set to 300 mm / min, and the non-woven fabric and the kanakin cloth were peeled off, and the peeling strength was measured. However, the maximum value of the measured load value was taken as the peel strength (N / 25 mm).
(2-6) Peeling strength between the protective sheet and the adhesive (A) and peeling strength between the non-woven fabric and the adhesive (B)
The peel strength (A) between the protective sheet and the pressure-sensitive adhesive and the peel strength (B) between the non-woven fabric and the pressure-sensitive adhesive were measured by the following procedure. First, the same non-woven fabric as the back sheet was impregnated with an adhesive at the same temperature as when the sanitary napkin was manufactured. Next, the non-woven fabric coated with the adhesive and the release sheet (A) or the cloth adhesive tape (Nitto cloth adhesive tape No. 750 manufactured by Nitto Denko CS System Co., Ltd.) (B) were bonded together. Subsequently, a pressure of 25 g / cm ² was applied to the laminated body of the laminated non-woven fabric and the release sheet (A) or the gum tape (B), and the mixture was left for 2 hours. Then, using a tensile tester (AG-1kNI manufactured by Shimadzu Corporation), one chuck sandwiches the longitudinal end of the nonwoven fabric, and the other chuck holds the release sheet (A) or the gum tape (B). The peeling strength was measured by peeling the non-woven fabric and the nylon cloth with the end portion in the longitudinal direction sandwiched, the distance between the chucks at the start of peeling was 20 mm, and the tensile (peeling) speed was 500 mm / min. However, the maximum value of the measured load value was defined as the peel strength (A) or the peel strength (B) (N / 25 mm).

(3) Results (3-1) Adhesive impregnation rate and surface film thickness In Examples 1 to 3, the impregnation rate was in the range of 30 to 80%. On the other hand, in Comparative Examples 1 and 2, the impregnation rate was out of the range of 30 to 80% except for the case where the basis weight of Comparative Example 2 was 20 g / m ² .
Further, in Examples 1 to 3, the surface film thickness (thickness of the exposed portion) was in the range of 10 to 50 μm. On the other hand, in Comparative Examples 1 and 2, the surface film thickness was outside the range of 10 to 50 μm except for the case where the basis weight was 20 g / m ² of Comparative Example 1.
(3-2) Melt Viscosity of Adhesive FIG. 5 is a graph of a viscosity curve showing the melt viscosity of the adhesive. The vertical axis represents the melt viscosity η (mPa · s), and the horizontal axis represents the temperature T (° C.). However, in the graph, Example 1 is G1 (dashed line), Example 2 is G2 (solid line), Example 3 is G3 (thick dashed line), Comparative Example 1 is G4 (thick solid line), and Comparative Example 2 is G5 (solid line). Dashed line) ,. It is the same in FIGS. 6 and 7. The melt viscosities of the pressure-sensitive adhesive are as follows at 120 ° C. In Examples 1 to 3, it was 4950 mPa · s, 8400 mPa · s, and 34050 mPa · s, respectively. On the other hand, in Comparative Examples 1 and 2, the values were 16500 mPa · s and 11500 mPa · s, respectively. Therefore, the melt viscosities of both Examples and Comparative Examples were in the range of 3000 to 40,000 mPa · s.
(3-3) Storage elastic modulus G', loss elastic modulus G', tan δ of adhesive
(A) Storage elastic modulus G'
FIG. 6 is a graph showing the storage elastic modulus of the pressure-sensitive adhesive. The vertical axis shows the storage elastic modulus G'(Pa), and the horizontal axis shows the temperature T (° C.). The storage elastic modulus of the pressure-sensitive adhesive is in the following numerical range at each temperature. At 80 ° C., in Examples 1 to 3, the range is 8.0 × 10 ² to 1.5 × 10 ⁴ Pa, and in Comparative Examples 1 and 2, 8.0 × 10 ² to 1.5 × 10 It was out of the range of ⁴ Pa. At 75 ° C., in Examples 1 to 3, the range is 1.0 × 10 ³ to 2.0 × 10 ⁴ Pa, and in Comparative Examples 1 and 2, 1.0 × 10 ³ to 2.0 × 10. It was out of the range of ⁴ Pa. At 50 ° C., in Examples 1 to 3, the range is 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa, and in Comparative Examples 1 and 2, 1.0 × 10 ⁴ except for Comparative Example 1. It was out of the range of ~ 2.0 × 10 ⁵ Pa. At 40 ° C., in Examples 1 to 3, the range is 2.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa, and in Comparative Examples 1 and 2, 2.0 × 10 ⁴ except for Comparative Example 1. It was out of the range of ~ 2.0 × 10 ⁵ Pa.
(B) tanδ
FIG. 7 is a graph showing the tan δ of the pressure-sensitive adhesive. The vertical axis represents tan δ, and the horizontal axis represents temperature T (° C.). The tan δ of the adhesive has the following numerical range at each temperature. At 80 ° C., in Examples 1 to 3, it was in the range of 1.0 to 5.0, and in Comparative Examples 1 and 2, it was out of the range of 1.0 to 5.0 except for Comparative Example 2. .. At 75 ° C., in Examples 1 to 3, it was in the range of 0.8 to 4.0, and in Comparative Examples 1 and 2, it was out of the range of 0.8 to 4.0. At 50 ° C., in Examples 1 to 3, it was in the range of 0.2 to 1.0, and in Comparative Examples 1 and 2, it was out of the range of 0.2 to 1.0 except for Comparative Example 1. .. At 40 ° C., in Examples 1 to 3, it was in the range of 0.20 to 0.90, and in Comparative Examples 1 and 2, it was out of the range of 0.20 to 0.90 except for Comparative Example 1. ..
(3-4) Adhesive residue test (user test)
No adhesive residue was generated with the adhesives of Examples 1 to 3, but adhesive residue was generated with the adhesives of Comparative Examples 1 and 2. In Comparative Example 1, since the adhesive did not impregnate the inside of the non-woven fabric (back sheet), the adhesive was peeled off from the non-woven fabric, and adhesive residue was generated. In Comparative Example 2, the adhesive was too impregnated into the non-woven fabric (back sheet) and the thickness of the exposed portion became thin, so that the adhesive strength became weak and the user said that the menstrual napkin was displaced from the underwear. there were. In addition, since the viscosity of the adhesive was low even at room temperature, the adhesive was easily torn, and although a small amount, adhesive residue was generated.
(3-5) Peeling Strength of Adhesive In Examples 1 to 3, the peeling strength of the pressure-sensitive adhesive was in the range of 0.7 to 8N / 25 mm. On the other hand, in Comparative Examples 1 and 2, the peel strength of the pressure-sensitive adhesive was out of the range of 0.7 to 8 N / 25 mm except for the case of the basis weight of 20 g / m ² of Comparative Example 1.
(3-6-1) Peeling strength between the protective sheet and the adhesive (A)
In Examples 1 to 3 and Comparative Examples 1 and 2, the peel strength (A) between the protective sheet and the pressure-sensitive adhesive was in the range of 0.1 to 0.6 N / 25 mm.
(3-6-2) Peeling strength between the non-woven fabric and the adhesive (B)
In Examples 1 to 3 and Comparative Examples 1 and 2, the peeling strength between the non-woven fabric and the pressure-sensitive adhesive was too strong, and the adhesive force of the gum tape did not peel off the pressure-sensitive adhesive from the non-woven fabric, and the pressure-sensitive adhesive was a non-woven fabric. The non-woven fabric was broken by being pulled by the gum tape together with a part. That is, the material was destroyed (material fracture).

However, in Table 1, in the adhesive residue test, ◯ indicates that there is no adhesive residue, and × indicates that there is adhesive residue. In the storage elastic modulus and tan δ, 〇 indicates that the numerical value falls within the predetermined range, △ indicates that the numerical value may not fall within the predetermined range depending on the temperature, and × indicates that the numerical value does not fall within the predetermined range. show.

(4) Summary As shown in the result of the adhesive residue test (user test), by using the samples (adhesives) of Examples 1 to 3 for the menstrual napkin, it is possible to prevent the adhesive residue from being generated in the underwear. There was found. From the impregnation rate of the samples of Examples 1 to 3 at that time, it was found that the impregnation rate of the pressure-sensitive adhesive should be in the range of 30 to 80%. Further, from the storage elastic modulus of the samples of Examples 1 to 3 at that time, the storage elastic modulus of the pressure-sensitive adhesive should be in the range of 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 50 ° C. Do you get it. The storage elastic modulus is preferably in the range of 8.0 × 10 ² to 1.5 × 10 ⁴ Pa at 80 ° C, and in the range of 1.0 × 10 ³ to 2.0 × 10 ⁴ Pa at 75 ° C. It was found that the range of 2.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa is preferable at 40 ° C. Further, from the tan δ of the samples of Examples 1 to 3 at that time, the tan δ of the pressure-sensitive adhesive is preferably in the range of 1.0 to 5.0 at 80 ° C., and 0.8 to 4.0 at 75 ° C. It was found that the range is preferable, the range of 0.2 to 1.0 is preferable at 50 ° C., and the range of 0.20 to 0.90 is preferable at 40 ° C. Further, from the peel strength of the samples of Examples 1 to 3 at that time, it was confirmed that the peel strength of the pressure-sensitive adhesive was 0.7 to 8N / 25 mm. Further, from the peel strength (A) between the protective sheet and the adhesive in the samples of Examples 1 to 3 at that time and the peel strength (A) between the protective sheet and the adhesive, [protective sheet and adhesive] It was confirmed that the peel strength (A) between the protective sheet and the adhesive <[peeling strength (A) between the protective sheet and the adhesive]. In addition, from the above results, it was found that there is not necessarily a large difference between the examples and the comparative examples in terms of melt viscosity.

10 Menstrual napkins (absorbent articles)
13 Back sheet (nonwoven fabric)
40 Adhesive 45 Impregnated part

Claims (9)

An absorbent article comprising a nonwoven fabric disposed on the non-skin side and an adhesive for fixing clothes applied to the surface of the nonwoven fabric on the non-skin side.
The pressure-sensitive adhesive contains an impregnated portion impregnated in the nonwoven fabric.
The ratio of the thickness of the impregnated portion to the thickness of the pressure-sensitive adhesive is 30 to 80%.
The storage elastic modulus of the pressure-sensitive adhesive is 1.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 50 ° C.
Absorbent article. The tan δ of the pressure-sensitive adhesive is 1.0 to 5.0 at 80 ° C.
The absorbent article according to claim 1. The tan δ of the pressure-sensitive adhesive is 0.20 to 0.90 at 40 ° C.
The storage elastic modulus of the pressure-sensitive adhesive is 2.0 × 10 ⁴ to 2.0 × 10 ⁵ Pa at 40 ° C.
The absorbent article according to claim 1 or 2. The tan δ of the pressure-sensitive adhesive is 0.8 to 4.0 at 75 ° C.
The storage elastic modulus of the pressure-sensitive adhesive is 1.0 × 10 ³ to 2.0 × 10 ⁴ Pa at 75 ° C.
The absorbent article according to any one of claims 1 to 3. The amount of the pressure-sensitive adhesive applied to the nonwoven fabric is 20 to 200 g / m ² .
The absorbent article according to any one of claims 1 to 4. The nonwoven fabric includes, in the thickness direction, a low density layer having a low fiber density and a high density layer having a high fiber density.
At least a part of the impregnated portion is impregnated into the high-density layer from the surface of the non-woven fabric.
The absorbent article according to any one of claims 1 to 5. The absorbent article has a squeezed portion and
At least a part of the impregnated portion overlaps with the compressed portion in a plan view.
The absorbent article according to any one of claims 1 to 6. It is placed on the non-skin side of the adhesive and further provided with a protective sheet to protect the adhesive.
The peel strength between the protective sheet and the pressure-sensitive adhesive is smaller than the peel strength between the pressure-sensitive adhesive and the non-woven fabric.
The absorbent article according to any one of claims 1 to 7. The absorbent article has a fold line and
The thickness of the impregnated portion at the position where it overlaps with the fold line in the thickness direction is larger than the thickness of the impregnated portion at the position where it does not overlap with the fold line in the thickness direction.
The absorbent article according to any one of claims 1 to 8.

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