JP4519052B2 - Absorbent article back sheet - Google Patents

Description

  The present invention relates to a back sheet of an absorbent article, and more particularly to a back sheet of an absorbent article, an absorbent article using the same, and the like.

  Conventionally, in absorbent articles such as sanitary napkins, panty liners (origami sheets), and incontinence pads, an adhesive layer is provided on the back sheet, and the absorbent article is fixed to clothing such as shorts via the adhesive layer. It is widely done. By fixing to shorts etc. via an adhesive layer, it can fix to an appropriate position easily and can prevent position shift during wearing. However, on the other hand, a sound is generated when the absorbent article is peeled off shorts or the like, which may cause anxiety to a user who does not want others to notice the use or replacement of the absorbent article.

  In Patent Document 1, an auxiliary sheet provided with a peeling processing part on the front surface and an adhesive part for fixing to underwear on the back surface is interposed between the absorbent article and the underwear, and the absorbent article is attached and detached. Methods have been proposed to reduce the sounds that are sometimes generated.

JP 2004-290546 A

  However, in the method described in Patent Document 1, an auxiliary sheet is indispensable, and the attached portion is thickened by the amount of the auxiliary sheet, so that the wearer tends to feel uncomfortable. Further, there is no description about measures against sound generated when the auxiliary sheet is peeled off from the underwear.

  Accordingly, an object of the present invention is to provide a back sheet of an absorbent article, an absorbent article using the same, and the like that can reduce sound when the absorbent article is peeled off from clothing such as shorts. .

  The present invention is a back sheet of an absorbent article in which a pressure-sensitive adhesive layer is provided on the clothing contact surface, and the absorbent article has a loss tangent (tan δ) at a temperature of 25 ° C. and a frequency of 2000 Hz of 0.2 to 3.0. The object is achieved by providing a back sheet.

  Further, the present invention is an absorbent article comprising the absorbent layer and the back sheet according to any one of claims 1 to 4, wherein a pressure-sensitive adhesive layer is provided on the clothing contact surface of the back sheet, The present invention provides an absorbent article in which the pressure-sensitive adhesive layer is formed using a hot-melt type pressure-sensitive adhesive containing 20 to 45% by mass of a softening agent.

  Further, the present invention provides an absorbent article comprising the absorbent layer and the back sheet according to any one of claims 1 to 4 and having a pressure-sensitive adhesive layer provided on the clothing contact surface of the back sheet. The package of an absorbent article, the absorbent layer, and the back surface according to any one of claims 1 to 4, which are housed in a packaging material having a display recommended to be used in combination with a shorts made of a cloth made of a tengu. Provided is an absorbent article set comprising a combination of an absorbent article provided with a sheet and a pressure-sensitive adhesive layer provided on the garment contact surface of the back sheet, and shorts made of a cloth with a crotch part It is.

According to the back sheet of the absorbent article of the present invention, it is possible to reduce the sound when the absorbent article is peeled off from clothing such as shorts.
According to the absorbent article of the present invention, it is possible to further reduce the sound when the absorbent article is peeled off from clothing such as shorts.
According to the package of absorbent articles and the absorbent article set of the present invention, it is possible to provide a combination of absorbent articles and shorts that is excellent in the sound reduction effect when the absorbent article is peeled off from the shorts.

  Hereinafter, the present invention will be described in detail based on preferred embodiments thereof.

  The back sheet of the absorbent article of the present invention has a loss tangent (tan δ, hereinafter simply referred to as “tan δ”) at a temperature of 25 ° C. and a frequency of 2000 Hz of 0.2 to 3.0. If tan δ is less than 0.2, the effect of reducing sound when the absorbent article is peeled off from clothing cannot be sufficiently obtained. If tan δ is more than 3.0, sufficient strength to be used as a back sheet. It becomes difficult to ensure.

  The reason for defining tan δ at a frequency of 2000 Hz for the back sheet is as follows. That is, when the state of the interface between the adhesive layer provided on the back sheet and the shorts when the absorbent article is peeled off from the clothing such as shorts is observed, the distance between the back sheet and the shorts increases. Along with that, a part of the adhesive is stretched between the back sheet and the shorts, and when part of the stretched adhesive leaves the shorts, it is found that the back sheet is vibrated to generate sound. did. When the frequency component of the sound (hereinafter also referred to as peeling sound) was analyzed using a sound level meter (“Normal Sound Level Meter NL-20” and “Small FFT Analyzer SA-78” manufactured by Rion Co., Ltd.), it was around 2000 Hz. It has been found that the peeling sound that is easily felt by humans can be effectively reduced by using a sheet material having a large tan δ at 2000 Hz as the back sheet. In addition, it is considered that the peeling noise decreases as tan δ increases because the vibration generated by the adhesive is dissipated as thermal energy from the sheet.

  The back sheet preferably has a tan δ at a temperature of 25 ° C. and a frequency of 2000 Hz of 0.5 to 2.0 from the viewpoint of further reducing the sound when the absorbent article is peeled off from the clothing and ensuring the strength. More preferably, it is 0.8-1.5.

The back sheet preferably has a storage elastic modulus E ′ at a temperature of 25 ° C. and a frequency of 2000 Hz of 5.0 × 10 ^{6 to} 1.0 × 10 ¹⁰ Pa, and 1.0 × 10 ^{7 to} 1.0 × 10. More preferably, it is ⁹ Pa.
When a resin film mainly composed of a thermoplastic elastomer is used as the sheet material constituting the back sheet, the higher the tan δ, the higher the adhesiveness. If the adhesiveness is too high, the sheets will block each other. Occurs, which is not preferable in the production of the back sheet and the absorbent article. However, by setting the storage elastic modulus E ′ of the back sheet to 5.0 × 10 ⁶ Pa or more, such blocking can be made difficult to occur, and the back sheet and the absorbent article can be stably manufactured. . Moreover, a sheet | seat can be formed flexibly by making the storage elastic modulus E 'of a back surface sheet into 1.0 * 10 < ¹⁰ > Pa or less.

  The back sheet is not particularly limited as long as the tan δ at a temperature of 25 ° C. and a frequency of 2000 Hz is 0.2 to 3.0 in dynamic viscoelasticity measurement, but from the viewpoint of molding processability, a thermoplastic elastomer It is preferably a resin film comprising a resin composition (including a thermoplastic elastomer having a mass of 100% by mass) or a laminate containing the resin film, and particularly an olefin-based thermoplastic elastomer or styrene-based heat. It is preferable that it is a resin film which consists of a resin composition which has a plastic elastomer as a main component, or a laminated body containing this resin film. The resin composition mainly composed of an olefin-based thermoplastic elastomer or a styrene-based thermoplastic elastomer has a content of olefin-based thermoplastic elastomer or styrene-based thermoplastic elastomer of 50 to 100% by mass, preferably 60 to 100%. It is mass%, More preferably, it is 70-100 mass%.

Examples of olefinic thermoplastic elastomers include ethylene-propylene copolymers, copolymers of ethylene and α-olefins such as 1-butene, 1-hexene and 1-octene, and ethylene-propylene rubber (EPM or EPDM in polypropylene). ) Are finely dispersed.
Examples of the styrenic thermoplastic elastomer include an AB type or ABA type block copolymer having a styrene component (A) and a rubber component (B). More specifically, a styrene-butadiene diblock copolymer and its hydrogenated product, a styrene-isoprene diblock copolymer and its hydrogenated product, a styrene-isobutylene diblock copolymer, and a styrene-vinyl isoprene block copolymer. AB type diblock copolymer such as polymer and hydrogenated product thereof, and styrene-butadiene-styrene triblock copolymer (SBS) and hydrogenated product thereof (SEBS), styrene-isoprene-styrene triblock copolymer (SIS) and its hydrogenated product (SEPS), styrene-isobutylene-styrene block copolymer (SIBS), styrene-vinylisoprene-styrene block copolymer (SVIS), and hydrogenated products thereof. A polymer is mentioned. These thermoplastic elastomers can be used singly or in combination of two or more.

  The AB type or ABA type block copolymer preferably has a styrene content (copolymerization ratio) of 5 to 80% by mass from the viewpoint of sheet strength and flexibility. More preferably, it is 50 mass%.

  The resin film constituting the back sheet is composed of a resin composition in which the thermoplastic elastomer described above is mixed with a thermoplastic resin other than the thermoplastic elastomer, or a plasticizer in order to improve molding processability. Also good. Examples of the thermoplastic resin herein include polyolefin resins such as polyethylene and polypropylene, ethylene-vinyl acetate copolymer (EVA) and its hydrolyzate, ethylene-methyl methacrylate copolymer (EMMA), and ethylene-acrylic acid. Examples thereof include modified polyethylene such as ethyl copolymer (EEA). Examples of the plasticizer include liquid rubbers such as paraffin oil, paraffin wax, liquid polybutene, liquid polyisoprene, and liquid polyisobutylene, carboxyl group-modified products, hydroxyl-modified products, and ethylene-α-olefin oligomers. Each of these thermoplastic resins and plasticizers can be used alone or in combination of two or more.

  As a method for forming a back sheet made of a resin film, a general method capable of melting a thermoplastic elastomer and forming it into a sheet can be used, and examples thereof include press molding, inflation molding, and T-die extrusion molding. Among these, inflation molding and T-die extrusion molding are preferable from the viewpoint of continuous productivity. A laminate including a resin film is formed by laminating a nonwoven fabric, a woven fabric, paper, or the like on the resin film thus obtained by various known methods and bonding the layers. Examples of the method for joining the layers of the laminate include heat fusion and adhesion with an adhesive. Further, the bonding between the layers of the laminated body may be bonded entirely or partially. In the case of a laminate of resin film and nonwoven fabric, woven fabric, paper, etc., the resin film is disposed on the clothing contact surface side. The thickness of the back sheet is preferably 15 to 100 μm, more preferably 30 to 50 μm from the viewpoint of strength and wearability.

  The back sheet of the absorbent article of the present invention is provided with the pressure-sensitive adhesive layer 6 on a surface (clothing contact surface) 31 that is in contact with clothing such as shorts, for example, like a sanitary napkin shown in FIG. It is preferably used as the back sheet 3 of the absorbent article.

  A sanitary napkin 1 shown in FIG. 1 has an absorbent layer 5 composed of a liquid-permeable top sheet 2 and a liquid-retaining absorbent 4 and a liquid-impermeable or water-repellent back sheet 3 integrated in a laminated state. A pressure-sensitive adhesive is applied to the clothing contact surface of the back sheet 3 to form a pressure-sensitive adhesive layer 6 for fixing the napkin 1 to clothing such as shorts (wearing tool). ing. The sanitary napkin 1 shown in FIG. 1 has a shape that is long in the same direction as the wearer's front-rear direction when worn, and the adhesive layer 6 has a rectangular shape with the longitudinal direction of the napkin 1 as the long side. It is formed and continuously formed over a length of about 50 to 95% with respect to the total length in the napkin longitudinal direction.

As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, conventionally known various pressure-sensitive adhesives can be used, but from the viewpoint of coating workability, it is preferable to use a hot-melt type pressure-sensitive adhesive.
As the hot-melt type pressure-sensitive adhesive, for example, those mainly composed of a styrene block polymer, a tackifier and a softener are preferably used.
Examples of the styrenic block polymer include styrene-butadiene diblock copolymers and hydrogenated products thereof, styrene-butadiene-styrene triblock copolymers and hydrogenated products thereof, styrene-isoprene block copolymers, and hydrogenated products thereof. Products, styrene-isoprene-styrene triblock copolymers and hydrogenated products thereof. From the viewpoint of adhesive strength, these styrenic block polymers preferably have a styrene portion having a molecular weight of 5000 to 20000 and a rubber portion having a molecular weight of 25,000 to 70000. The tackifier is a polyterpene resin which is a copolymer of C5 petroleum resin, C9 petroleum resin, α-pinene, β-pinene or dipentene having a softening point of 10 ° C. or less and a number average molecular weight of 400 to 2000. , Rosin resins, or hydrogenated products thereof. Examples of the softener include process oil having a softening point of 10 ° C. or less and a number average molecular weight of 150 to 700, various plasticizers, polybutene, and liquid resin.
These styrenic block polymers, tackifiers and softeners can be used singly or in combination of two or more.
The content of the softening agent is preferably 20 to 45% by mass, more preferably 24 to 38% by mass, and still more preferably 28 to 38% by mass with respect to the total amount of the adhesive, in view of reduction in peeling sound and adhesiveness. 32% by mass.
The basis weight of the pressure-sensitive adhesive layer can be, for example, 10 to 100 g / m ^2, and preferably 30 to 60 g / m ² .

  The absorbent article using the back sheet of the present invention or the absorbent article according to the present invention is usually a pressure-sensitive adhesive layer provided on the clothing contact surface of the back sheet or clothing such as shorts via the provided pressure-sensitive adhesive layer. And is attached to the wearer in that state. The back sheet and absorbent article of the present invention have an effect of reducing peeling sound regardless of the material of clothing, but the crotch portion was used in combination with a fabric made of a woven fabric, particularly a cotton woven fabric. In some cases, the peeling noise is further reduced.

Absorbent articles such as sanitary napkins, panty liners (origami sheets), and incontinence pads are generally distributed (commercially available) separately from shorts. From the viewpoint of being able to be used in combination with shorts, the absorbent article using the back sheet of the present invention or the absorbent article according to the present invention is used in combination with shorts whose crotch portion is made of a woven fabric. It is preferable that the product is stored in a packaging material (a packaging bag made of a resin film material, a box made of paper, etc.) with a display recommending this and distributed (commercially available) as a package of absorbent articles. A display that recommends the crotch part to be used in combination with shorts made of woven cloth is a display that identifies such shorts by product name or product number and recommends the use of shorts such as product name or product number. There may be.
Alternatively, the absorbent article using the back sheet of the present invention or the absorbent article according to the present invention is combined with shorts made of a cloth with a crotch knitted fabric, and distributed as an absorbent article set ( (Commercially available etc.).

  In addition to sanitary napkins, the absorbent article in the present invention may be panty liners (origami sheets), incontinence pads, and the like. The configuration of the absorbent article other than the back sheet is not particularly limited, and can be the same as a known one. For example, non-woven fabrics or apertured films produced by various manufacturing methods can be used as the surface sheet, and the absorbent body can be a fiber aggregate of hydrophilic fibers or a combination of this and a polymer water-absorbing polymer. Can do. Further, the absorbent article may or may not have a so-called wing, and both side portions of the top sheet are not wound between the absorbent body 4 and the back sheet 3. In addition, the outer periphery of the absorber 4 may be joined to the back sheet 3.

The shape of the pressure-sensitive adhesive layer in a plan view can also be in an appropriate form, and can be in the same form as conventionally known various forms. For example, instead of the rectangular pressure-sensitive adhesive layer described above, a pressure-sensitive adhesive layer having an elliptical shape, a circular shape, a rhombus shape, a square shape, a pentagonal shape, a hexagonal shape, or the like can be provided. Further, a plurality of pressure-sensitive adhesive layers may be formed separated in the width direction and / or the longitudinal direction of the napkin, for example, a belt-like pressure-sensitive adhesive layer extending in the width direction of the napkin and / or a belt-like pressure-sensitive adhesive layer extending in the longitudinal direction. A large number of agent layers may be provided, and the adhesive layer may be dispersed and arranged in a dot shape (scatter pattern) or a checkered pattern.
The back sheet is preferably made of a single-layer resin film having a tan δ at a temperature of 25 ° C. and a frequency of 2000 Hz as described above.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not restrict | limited at all by the following Examples.
[Example 1] 100% of an olefinic thermoplastic elastomer (Prime TPO M142E manufactured by Prime Polymer Co., Ltd., content of olefinic thermoplastic elastomer of more than 50% by mass) was charged into a T-die molding machine at a temperature of 200 ° C. Molding was performed to obtain a sheet having a thickness of 35 μm. Using the obtained sheet as a back sheet, a sanitary napkin having a width of 10 cm and a length of 22 cm was produced.
The sanitary napkin was manufactured by sandwiching an absorbent body wrapped in a backing sheet between a top sheet and a back sheet and joining the periphery of both sheets by heat sealing. A space between the absorber wrapped in the mount and the back sheet was fixed with a hot melt adhesive. Except for the back sheet, the same material as that of a commercially available sanitary napkin “Lorie Sarasara Cushion (trade name)” manufactured by Kao Corporation was used.
On the garment contact surface of the back sheet, a hot melt composed of 15% by mass of styrene-butadiene-styrene copolymer (SBS), 55% by mass of hydrogenated petroleum resin (tackfire), and 30% by mass of oil (softener). The mold pressure-sensitive adhesive was applied so as to have a width of 3 cm, a length of 10 cm, and a basis weight of 30 g / m ² to form a pressure-sensitive adhesive layer.

[Example 2]
AB type styrenic thermoplastic elastomer [Kuraray Co., Ltd. Hibler 7350 (styrene content 50 mass%, rubber component: vinyl isoprene hydrogenated 50 mass%)] was added to the T-die molding machine as a back sheet material. Produced a sanitary napkin in the same manner as in Example 1.

Example 3
AB type styrene thermoplastic elastomer [Hibura 7311S (Kuraray Co., Ltd., styrene content 12% by mass, rubber component: vinyl isoprene hydrogenated 88% by mass)] was added to the T-die molding machine as a back sheet material. Produced a sanitary napkin in the same manner as in Example 1.

Example 4
ABA type thermoplastic elastomer [HYBRAR7311S (styrene content: 12% by mass, rubber component: vinyl isoprene hydrogenated: 88% by mass)] manufactured by Kuraray Co., Ltd. and linear low density polyethylene (Ultzex manufactured by Prime Polymer Co., Ltd.) A sanitary napkin was manufactured in the same manner as in Example 1 except that 50% by mass of UZ4050) was added to the T-die molding machine as the material for the back sheet.

Example 5
A sanitary napkin was produced in the same manner as in Example 4. However, an adhesive comprising 25% by mass of styrene-butadiene-styrene copolymer (SBS), 55% by mass of a hydrogenated petroleum resin (tackfire), and 20% by mass of a softening agent is applied to the clothing contact surface of the back sheet. It was applied so as to have a width of 3 cm, a length of 10 cm, and a basis weight of 30 g / m ² .

[Comparative Example 1]
A sanitary napkin was produced in the same manner as in Example 1 except that pellets of linear low density polyethylene (Ultzex UZ4050 manufactured by Prime Polymer Co., Ltd.) were put into a T-die molding machine as a material for the back sheet.

[Measurement of viscoelasticity]
The backsheets obtained in the examples and comparative examples were cut into a width of 5 mm and a length of 20 mm, and the dynamic viscoelasticity of the backsheet was measured using a dynamic viscoelasticity measuring device (SII It was measured with Nano Technology Co., Ltd. DMS6100. The measurement conditions are as follows. The measurement results are shown in Table 1.
Deformation mode: Film shear mode Measurement frequency: 0.5, 1, 2, 5, 10 Hz
Measurement temperature range: -130 ° C to + 120 ° C
Temperature increase rate: 2 ° C / min Atmosphere: Nitrogen gas 200mL / min From the master curve (created by SII Nano Technology Co., Ltd. Master Curve Analysis Program) created by the temperature-time conversion rule using the obtained measurement results E ′ and tan δ at 2000 Hz were derived.

[Evaluation of film blocking properties]
In the example and the comparative example, “○” indicates that the sheet can be pulled out from the sheet wound around the paper tube having a diameter of 10 cm at the time of manufacturing, “△” indicates that the sheet can be pulled out, but “Δ” indicates that the sheets are adhered. The case where it was not possible to withdraw was designated as “x”. In the case of “△” and “○”, it was judged that handling was possible. The evaluation results are shown in Table 1.

[Evaluation of peeling noise reduction effect]
The adhesive surface of the sanitary napkin obtained in the examples and comparative examples was attached to shorts made of a cotton knitted crotch cloth, and then the peeling sound when the napkin was peeled was evaluated by the following method. . First, using a roller having a mass of 2 kg (diameter 60 mm, width 65 mm), the roller was rolled back and forth, and the napkin was pressure-bonded to the shorts. In addition, as a comparative reference product, a commercially available sanitary napkin “Laurie Sarasara Cushion (trade name)” manufactured by Kao Corporation was crimped to shorts having the same configuration in the same manner. Then, 10 panelists were allowed to peel off the napkins and comparative reference products of the examples or comparative examples to be evaluated from the shorts, and evaluated the magnitude of the sound generated during the peeling.
When 10 panelists (all members) answered that the evaluation sound of the napkin to be evaluated was reduced compared to the napkin of the reference product, “◎”, 8 to 9 peeled off. “○” indicates that the sound has been reduced, “△” indicates that five to seven people have reduced the peeling sound, and “×” indicates that four or less have said that the peeling sound has been reduced. It was evaluated. In the case of “△”, “◯”, and “◎”, it was judged that there was an effect of reducing peeling noise. The evaluation results are shown in Table 1.
In addition, for the sanitary napkin of Example 4, the crotch part is the same as the above method except that the crotch part is made of pile fabric shorts (“Korean Co., Ltd.“ Lorrie Active Guard Outing Mode ”). The effect of reducing peeling noise in the case of a pile was evaluated. The results are shown in Table 1 as Example 4-2.

  From the results shown in Table 1, it can be seen that peeling sound is reduced in the sanitary napkin (back sheet) of the example.

FIG. 1 is a schematic cross-sectional view showing a cross-section in the width direction of a sanitary napkin that is an example of an absorbent article according to the present invention.

Explanation of symbols

1 Sanitary napkin (absorbent article)
2 Surface sheet 3 Back sheet 4 Absorber 5 Absorbent layer 6 Adhesive layer

Claims (6)

A back sheet of an absorbent article provided with a pressure-sensitive adhesive layer on the clothing contact surface,
Loss tangent (tan δ) at a temperature of 25 ° C. and a frequency of 2000 Hz is 0. 5 to 3.0 ,
It is composed of a resin film containing 50% by mass or more of a styrene thermoplastic elastomer, and the styrene thermoplastic elastomer is an AB type or ABA type block copolymer having a styrene component (A) and a rubber component (B). Yes, the content of the styrene component (A) in the styrenic thermoplastic elastomer is 5 to 80% by mass,
The pressure-sensitive adhesive layer is formed using a hot-melt type pressure-sensitive adhesive containing 20 to 45% by mass of a softening agent,
The back sheet of an absorbent article , wherein the absorbent article is a sanitary napkin . A back sheet of an absorbent article provided with a pressure-sensitive adhesive layer on the clothing contact surface,
Loss tangent (tan δ) at a temperature of 25 ° C. and a frequency of 2000 Hz is 0.5 to 3.0,
An AB-type or ABA-type block comprising a laminate comprising a resin film containing 50% by mass or more of a styrene-based thermoplastic elastomer, the styrene-based thermoplastic elastomer having a styrene component (A) and a rubber component (B) A copolymer, the content of the styrene component (A) in the styrenic thermoplastic elastomer is 5 to 80% by mass, and the resin film forms the clothing contact surface;
The pressure-sensitive adhesive layer is formed using a hot-melt type pressure-sensitive adhesive containing 20 to 45% by mass of a softening agent,
Absorbent article is a sanitary napkin backsheet of the absorbent article. The back sheet of an absorbent article according to claim 1 or 2 , wherein the storage elastic modulus E 'at a temperature of 25 ° C and a frequency of 2000 Hz is 5.0 x 10 ^{6 to} 1.0 x 10 ¹⁰ Pa. Intake Osamusei articles with backsheet according to any one of the absorbing layer and the claims 1-3. The intake Osamusei articles with backsheet according to any one of the absorbing layer and the claims 1-3, the packaging material having a display crotch portion is recommended to use in combination with the shorts made of fabric sheeting Hen A package of absorbent articles that is stored. A suction Osamusei articles with backsheet according to any one of the absorbing layer and the claims 1-3, comprising a combination of a shorts crotch portion consists of cloth jersey knitting, the absorbent article set.

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