JP2001104374A - Absorbent article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorbent article resisting discoloring although made from a material that is easy to discolor, such as urethane foam, and maintaining its appearance by hiding its discolored part, if any, from the outside. SOLUTION: The absorbent article of the invention has a liquid-retaining absorbing layer and a liquid-impermeable leakproof layer, with the leakproof layer having a sheet material with an ultraviolet transmission of 10% or less, a whiteness of 65 or more and a total light ray transmission of 35% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbent article such as a disposable diaper or a sanitary napkin, and more particularly, it is hard to be discolored. It relates to an absorbent article.

[0002]

2. Description of the Related Art When an absorbent article such as a disposable diaper or a sanitary napkin is exposed to sunlight for a long period of time, ultraviolet rays cause an ink commonly used in the absorbent article to be exposed. Materials such as adhesives, plastics, and rubbers may be discolored, which may impair the appearance of the absorbent article.

[0003] By the way, in order to obtain an absorbent article having a high fit when worn, an absorbent article using urethane foam as a cushion material is known. For example, Japanese Unexamined Patent Publication (Kokai) No. 51-66194 discloses an elastic and moisture-stable foam layer between an absorbent core and a backing sheet, which is capable of holding and holding the absorbent core in the perineum of a wearer. Are disclosed, and a polyurethane foam is shown as the foam layer. However, urethane foam has a disadvantage that it is easily discolored by ultraviolet rays. Further, since the foamed layer is formed as a large-sized component in the napkin, if it is discolored, the appearance of the napkin will be significantly impaired, giving the user an uneasy feeling.

[0004] In order to prevent such discoloration of the urethane foam, there has been conventionally attempted a method in which an ultraviolet absorber, a white pigment, or the like is directly blended into the urethane foam to improve the urethane foam so as to be hardly discolored. However, the discoloration preventing effect was insufficient with this method.

[0005] Absorbent articles are discolored by not only ultraviolet rays but also chemical substances such as nitrogen oxide gas. Therefore, the method of considering only the discoloration due to ultraviolet rays cannot solve the problem of the discoloration of the absorbent article.

Accordingly, it is an object of the present invention to provide an absorbent material which does not easily discolor even when a material which easily discolors, such as urethane foam, is used, and which does not easily become visible from the outside even if the discoloration occurs. To provide articles.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an ultraviolet ray transmittance is 10% or less, a whiteness is 65 or more, and a total light transmittance is 35%.
The above object has been attained by providing an absorbent article comprising a sheet material which is not more than 10%.

The present invention also provides an absorbent article having a liquid-retentive absorbing layer and a liquid-impermeable leakproof layer, wherein urethane foam is arranged between the absorbent layer and the leakproof layer. A sheet material is disposed between the leak-proof layer and the urethane foam, wherein the urethane foam is
Density is 5-35 kg / m ³ , no-load thickness is 1-10 m
m, compression recovery rate (b / a) [a;
Thickness after standing for 4 hours (thickness before compression) (mm),
b; after compression for 24 hours at a pressure of 17.6 kPa, the pressure was removed and the thickness (mm) when allowed to stand for 30 minutes was 6
0% or more, and the sheet material has an ultraviolet transmittance of 10%.
%, The whiteness is 65 or more, and the total light transmittance is 35% or less.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an absorbent article according to the present invention will be described based on preferred embodiments with reference to the drawings.
As shown in FIGS. 1 to 3, the disposable diaper 1 of the present embodiment includes a liquid-permeable top sheet 2, a back sheet 3 as a liquid-impermeable leakproof layer, and the top sheet 2 and the back sheet 3.
Absorber 4 as a liquid-retentive absorbing layer interposed between
Is provided.

The back sheet 3 has substantially the same size as the absorber 4. On the outer side of the back sheet 3, an outer layer nonwoven fabric 5 is disposed. A water-repellent nonwoven fabric 61 for forming three-dimensional gathers 6 is arranged on the topsheet 2 extending laterally from both left and right edges of the absorber 4. The outer nonwoven fabric 5 and the water-repellent nonwoven fabric 61 are both extended to the left and right side edges of the absorber 4, and sandwich and fix the leg elastic members 71 to form a pair of left and right leg gathers 7. Water-repellent nonwoven fabric 61
A three-dimensional gather elastic member 63 for forming the three-dimensional gathers 6 is disposed on the free edge portion 62 of the first embodiment.

At both longitudinal ends of the disposable diaper 1, an outer nonwoven fabric 5 and a topsheet 2 extend from both longitudinal ends of the absorber 4, and a pair of waist members 8 are provided.
Is formed. The waist portion 8 is provided with a sheet-like waist elastic member 81, which is sandwiched and fixed between the topsheet 2 and the outer nonwoven fabric 5. Fastening tapes 11 for fastening are arranged on both left and right side edges B1 and B2 of the back side portion B. On the other hand, a fastening portion 51 for fastening the fastening tape 11 is provided on the surface of the outer nonwoven fabric 5 in the abdominal portion A. As these members, the same members as those usually used for disposable diapers can be used.

As shown in FIGS. 2 and 3, a foam material 10 made of a urethane foam sheet is disposed between the back sheet 3 and the absorber 4. Since the foam material 10 has a high compression recovery property, the disposable diaper 1 of the present embodiment can be folded and compressed into a thin and compact package at the time of packaging, and can recover its thickness at the time of use. Gives the user a sense of security against leakage and the like. However, as described above, urethane foam has a disadvantage that it is easily discolored by ultraviolet rays, nitrogen oxide gas or the like.

Thus, the disposable diaper 1 of the present embodiment.
Has a specific sheet material.

The sheet material is used as a back sheet 3. The sheet material has an ultraviolet transmittance of a specific value or less, a whiteness of a specific value or more, a total light transmittance of a specific value or less, a moisture permeability of a specific value or more, and a resistance of a specific value or more as described below. Has water pressure. By forming the back sheet 3 from the sheet material, the discoloration prevention and hiding of the foam material 10, which is a component that is easily discolored, and the structure of the diaper are simplified, which is preferable.

The sheet material has an ultraviolet transmittance of 10%.
% Or less. The sheet material having an ultraviolet transmittance of 10% or less is used so as to cover the discolorable portion of the disposable diaper, thereby suppressing the transmission of the ultraviolet light and suppressing the discoloration of the coated portion due to the ultraviolet light. it can. The ultraviolet transmittance is preferably 8% or less, more preferably 5% or less. The lower limit of the ultraviolet transmittance is not limited, and is preferably as close to 0 as possible. The ultraviolet rays have a wavelength of 380 nm. UV transmittance is
UV spectrophotometer (UV) MPS-, manufactured by Shimadzu Corporation
Measure using Model 2000.

The sheet material has a whiteness of 65 or more,
It is preferably at least 68, more preferably at least 70, and its total light transmittance is at most 35%, preferably at most 33%, more preferably at most 30%. When the whiteness is equal to or more than the above value and the total light transmittance is equal to or less than the above value, the concealability of the sheet material is enhanced. For this reason, even if the covering portion is discolored by a chemical substance such as nitrogen oxide gas, the discoloration can be made difficult to see from the outside, and the appearance of the diaper is not impaired.

The whiteness is determined according to JIS Z 8722.
For example, a color difference meter SZ- # 80 manufactured by Nippon Denshoku Industries Co., Ltd.
It is measured using [W (Lab) value is defined as whiteness]. The total light transmittance is measured according to JIS K7105, for example, using a haze / transmission / reflectometer HR-100 manufactured by Murakami Color Research Laboratory. The wavelength range of this light is visible light of 380 to 800 nm.

The sheet material preferably has moisture permeability. That is, the sheet material has an ultraviolet transmittance of not more than the above value, a whiteness of not less than the above value, and a total light transmittance of not more than the above value, and has a moisture permeability of 1 k.
g / (m ² · 24 hr) or more, especially 2.4 kg / (m ²
・ 24hr) or more, especially 3kg / (m ²・ 24h)
r) or more and the water pressure resistance is preferably 4.9 kPa or more, particularly 10 kPa or more, especially 10 to 20 kPa or more, from the viewpoint of preventing the occurrence of stuffiness and rash. The upper limit of the moisture permeability and the water pressure resistance of the sheet material is determined from the balance between the two, and the upper limit of the moisture permeability in practice is 7.2 kg /
(M ² · 24 hr) and the upper limit of the water pressure resistance is about 30 kPa.

The moisture permeability is determined according to JIS Z 0208.
Measured. According to JIS L 1092,
Measured. The test is performed by the hydrostatic pressure method A (low pressure method).

The thickness of the sheet material is 10 to 100 μm.
m, and particularly preferably from 15 to 50 μm, from the viewpoint of making the diaper compact and improving ease of use.

It is preferable that the sheet material is mainly composed of a thermoplastic resin, particularly a polyolefin resin. Examples of the polyolefin-based resin include polyolefin-based resins described in page 3, column 3, lines 1 to 29 of Japanese Patent Application Laid-Open No. 9-268234, filed by the present applicant, and one or two of these resins. More than species can be used. In particular,
From the viewpoints of flexibility, strength, and stretchability, it is preferable to use linear low-density polyethylene. The sheet material contains the polyolefin-based resin in an amount of 10 to 50% by weight, particularly 20 to 50% by weight.
It is preferable to contain 45% by weight in view of strength and moisture permeability.

The sheet material is preferably made of titanium oxide from the viewpoint that the UV transmittance and the total light transmittance are set to the above values and the whiteness is set to the above values. The sheet material contains 1 to 25% by weight of titanium oxide, particularly 2 to 20% by weight.
It is preferred that the content is contained by weight because a sheet material having a low ultraviolet transmittance and a total light transmittance, a high whiteness, and a sufficient strength can be obtained. The particle size of titanium oxide is 0.1
To 1.0 μm, especially 0.2 to 0.4 μm,
It is preferable because the concealing property is enhanced and the thickness of the sheet material is made uniform.

The sheet material preferably contains an ultraviolet absorber in an amount of 0.2 to 1.0% by weight, particularly 0.3 to 0.6% by weight, from the viewpoint of lowering the ultraviolet transmittance. If the amount is less than 0.2% by weight, a decrease in the ultraviolet transmittance of the sheet material cannot be expected. If the amount exceeds 1.0% by weight, sheet formability will be reduced. Examples of the ultraviolet absorber include a salicylic acid-based ultraviolet absorber such as phenyl salicylate, a benzophenone-based ultraviolet absorber such as 2,4-dihydroxybenzophenone, and 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl). ) -5-chlorobenzotriazole and other benzotriazole UV absorbers, and 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate and other cyanoacrylate UV absorbers are particularly preferred from the viewpoint of UV absorption and moldability. It can be used preferably.

The moisture-permeable sheet of the present invention preferably contains an inorganic filler from the viewpoint of making the moisture permeability equal to or more than the above value. As the inorganic filler, for example, one or two or more of the inorganic fillers described in JP-A-9-268234, page 3, column 4, lines 9 to 42 can be used. . The moisture-permeable sheet of the present invention preferably contains 10 to 80% by weight, particularly 20 to 70% by weight of an inorganic filler, since a sheet having high moisture permeability and sufficient strength can be obtained. The average particle size is preferably 50 μm or less, more preferably 10 μm or less, and 0.5 μm or less.
５5 μm is most preferred. If the average particle size exceeds 50 μm, the denseness of the pores becomes poor, and the resulting sheet tends to ooze out of the liquid. In addition, the average particle size is 0.5
If it is less than μm, the dispersibility of the inorganic filler in the resin composition may be poor, and the sheet may have poor moldability.

The moisture-permeable sheet of the present invention preferably contains a plasticizer (softening agent) from the viewpoint of dispersibility of the inorganic filler. As the plasticizer, for example, a plasticizer described in page 3, line 3, line 36 to column 4, line 2 of JP-A-5-230252, which is filed by the applicant of the present invention, is used. In particular, it is preferable to use a plasticizer having not only a function of plasticizing the resin but also a function of uniformly dispersing the inorganic filler, since a dispersion effect can be obtained without adding a separate dispersant. Particularly preferred plasticizers are esters of fatty acids and alcohols, fatty acid amides, ketone resins, silicone oils and the like. The content of the plasticizer is preferably 0.1 to 20% by weight, more preferably 1 to 10%.
% By weight. If the content of the plasticizer is less than 0.1% by weight, a plasticizing effect cannot be substantially obtained. If the content is more than 20% by weight, bleed out occurs on the surface of the obtained film, and stickiness and deterioration of texture are caused. May result in poor adhesion.

In addition to the above-mentioned components (polyolefin resin, titanium oxide, ultraviolet absorber, inorganic filler and plasticizer), an antioxidant, if necessary,
Additives such as stabilizers and colorants can be appropriately compounded. The amount of these additives is preferably 0.01 to 1
0% by weight, more preferably 0.1 to 5% by weight.

[0027] The sheet material is selected from the viewpoints of physical properties and cost.
A resin composition containing at least the polyolefin-based resin, the titanium oxide, the ultraviolet absorber, the inorganic filler, and the plasticizer is formed into a film-shaped product, and the film-shaped product is subjected to a stretching treatment. It is preferred that it is formed by. Specifically, for example, Japanese Patent Application Laid-Open
No. 268234, page 4, column 6, line 30 to page 5, page 7
As described in column 12, line, the resin composition
After kneading with a biaxial kneading extruder or the like to form pellets, forming the pellets into a film-shaped molded product using a circular die or the like, the film-shaped molded product is stretched at least in a uniaxial direction by a tenter stretching machine or the like. It is preferable that the micropores are formed. By obtaining the sheet material by such a method, the moisture permeability and the water pressure resistance can each be equal to or more than the above values, and the total light transmittance can be further reduced.

The foam material 10 preferably has a density of 5 to 35 kg / cm 2 from the viewpoint of improving its moldability.
m ³ , more preferably 5 to 20 kg / m ³ . In addition, the foam material 10 preferably has a non-load thickness of 1 to 10 m from the viewpoint of exhibiting appropriate cushioning properties.
m, more preferably 1.7 to 5 mm. The unloaded thickness is measured using a laser displacement meter (manufactured by Keyence Corporation, model “PA”).
-1830 ") and measured according to a standard method.

The foam material 10 has a compression recovery rate (b /
a) is preferably at least 60%, more preferably at least 70%, even more preferably at least 90%. By setting the compression recovery rate to be equal to or more than the above value, the disposable diaper 1 of the present embodiment is compact when packaged, but becomes a diaper that provides a sense of security when worn. In addition, a;
Thickness after standing for a time (thickness before compression) (mm), b;
This is the thickness (mm) when the sample is compressed at a pressure of 17.6 kPa for 24 hours, then the pressure is removed and the sample is left for 30 minutes. The thickness is measured using a laser displacement meter (Keyence Corporation, model "PA-
1830 ").

The urethane foam forming the foam material 10 is not particularly limited as long as it is foamed or porous, but it is preferable to use an ether-based polyurethane foam from the viewpoint of reducing the weight of the diaper.

When the disposable diaper 1 of this embodiment is formed into a package, it is appropriately folded and laminated as usual.
It is compressed and stored in a packaging bag. The thickness of the disposable diaper 1 of the present embodiment when packaged in this manner is substantially the same as that when a foam material having no compression recovery rate is used. When the disposable diaper 1 is taken out and used, the foam material 10 recovers to a thickness satisfying the compression recovery rate.

In the disposable diaper 1 of the present embodiment, the back sheet 3 has an ultraviolet transmittance of not more than the above values, a whiteness of not less than the above values, a total light transmittance of not more than the above values, and a moisture permeability of not less than the above values. And since it is formed from the sheet material having a water pressure resistance not less than the above value, the discoloration of the foam material 10 due to ultraviolet rays can be suppressed without complicating the structure of the diaper, and the foam material 10 is made of a nitrogen oxide gas Even if the discoloration is caused by the above, the discoloration is hardly seen from the outside, and the appearance of the diaper is not spoiled. Further, practically, stuffiness and rash are effectively prevented.

Further, the disposable diaper 1 of the present embodiment comprises:
Since the foam material 10 having the density within the above range, the thickness under non-load within the above range and the compression recovery rate not less than the above value is arranged at a predetermined position, at the time of packaging, it is thin and compact by folding and compressing. When used, the package recovers its thickness and has an appropriate thickness, so that it can be used with confidence without giving the user or the like an uneasiness due to the thinness.

As another embodiment of the present invention, the diaper may have the following configuration. That is, a back sheet formed of a normal material is used as the back sheet, the foam material is arranged between the back sheet and the absorber, and the sheet material is interposed between the back sheet and the foam material. May be arranged. Even with the diaper having this configuration, as will be apparent from the examples described later, the components of the diaper are hardly discolored, and even if discolored, it is difficult to see from the outside, so that the appearance of the diaper is not impaired. The shape and size of the sheet material are not particularly limited. However, from the viewpoint of prevention of discoloration and concealment of discolored portions, the sheet material has a shape and size that can completely cover the discolorable member (part) of the diaper. Is preferably arranged so as to completely cover. In this case, the sheet material may be disposed and fixed at a predetermined position by, for example, bonding the sheet material with a hot melt adhesive or heat sealing with another member. Alternatively, they may be simply arranged at predetermined positions without being fixed.

The absorbent article of the present invention is not limited to the above embodiment. For example, in the embodiment, the sheet material is used as a back sheet, or the sheet material is arranged between a normal back sheet and the foam material. A sheet material other than the above may be further used to cover each part individually. The absorbent article of the present invention is a deployable disposable diaper in the above embodiment, but may be an absorbent article such as a pants-type disposable diaper, a sanitary napkin, an incontinence pad, and the like.

[0036]

Examples 1 to 5 and Comparative Examples 1 and 2 The moisture-permeable sheets obtained according to the following resin composition preparation, film-forming and stretching treatments were measured according to the above-mentioned measuring methods.
Each physical property such as ultraviolet transmittance, whiteness, total light transmittance, moisture permeability and water pressure resistance was measured. The results are shown in Table 2 below.

Preparation of Resin Composition The blended components as shown in Table 1 below were mixed with a 100 L Henschel mixer, and then a 45 mm diameter twin screw extruder (PCM-45-33.5, manufactured by Ikegai) Thus, the resin composition was kneaded under the conditions of a set temperature of 160 ° C. and a screw rotation speed of 150 rpm to obtain a pelletized resin composition.

[0038]

[Table 1]

Film-shaped forming process Single screw extruder (L / D = 28) with a diameter of 50 mm and a diameter of 100 m
The resin composition was formed into a tubular film having a film thickness of 45 μm and a folding width of 390 mm using an inflation molding equipment comprising a circular die (lip clearance: 1 mm) having a basis weight of 40 g / m ² . A molded product was obtained. In addition, the film-formation condition is set temperature 1
60 ° C., discharge rate 25 kg / h, blow ratio 2.5.

Stretching treatment Preheating roll, stretching roll, annealing roll, cooling roll (roll diameter is 100 mm for stretching roll, 600 mm for other
mm, the width is 600 mm)
Set the roll set temperature to 80 ° C for the preheating roll and 50 for the stretching roll.
℃, annealing roll 80 ℃, stretch ratio of 2.1
The film-like molded product is uniaxially stretched at a thickness of 2.
A moisture-permeable sheet having a thickness of 0 μm and a basis weight of 20 g / m ² was obtained.

[0041]

[Table 2]

[0042]

Examples 6 to 15 and Comparative Examples 3 and 4 Examples 1 to 5
Further, the moisture-permeable sheets obtained in Comparative Examples 1 and 2 were each used as a back sheet, and the top sheet had a basis weight of 30 fibers made of polypropylene core and polyethylene sheath.
g / m ² air-through non-woven fabric, a heat-rolled non-woven fabric having a basis weight of 20 g / m ² made of polypropylene fiber as the outer non-woven fabric, and using other known members, disposable diapers shown in FIGS. (Examples 6 to 1)
0 and Comparative Examples 3 and 4). Further, as another disposable diaper, a disposable diaper having the same configuration as the disposable diaper shown in FIGS. 1 to 3 except that the back sheet is formed from a normal material and the moisture permeable sheet is disposed between the back sheet and the foam material. Diapers were produced (Examples 11 to 15). Regarding the obtained disposable diaper, according to the following evaluation criteria, "N
The degree of discoloration due to O gas and the degree of discoloration due to ultraviolet irradiation were evaluated. The results are shown in Table 3 below.

Evaluation Criteria for “Degree of Discoloration Due to NO Gas” The diaper was left in 200 ppm NO gas for 5 hours and evaluated according to the following criteria. A: There is no discoloration of the diaper and there is no anxiety about use. ○: Discoloration of the diaper is slightly observed, but there is no anxiety about use. Δ: Discoloration of the diaper was recognized, and there was some anxiety about use. ×: Discoloration of the diaper is clearly recognized, and anxiety about use is large.

Evaluation Criteria for “Degree of Discoloration Due to Irradiation with Ultraviolet Light” The diaper was irradiated with ultraviolet light for 24 hours using a carbon arc type fade meter, and then evaluated according to the following criteria. A: There is no discoloration of the diaper and there is no anxiety about use. ○: Discoloration of the diaper is slightly observed, but there is no anxiety about use. Δ: Discoloration of the diaper was recognized, and there was some anxiety about use. ×: Discoloration of the diaper is clearly recognized, and anxiety about use is large.

[0045]

[Table 3]

[0046]

The absorptive article of the present invention is hardly discolored, and even if it is discolored, it is hardly seen from the outside and the appearance is not impaired.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a disposable diaper as an absorbent article of the present invention.

FIG. 2 is a sectional view showing a section taken along line XX of FIG. 1;

FIG. 3 is a sectional view showing a section taken along line YY of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Disposable diaper 11 Fastening tape 2 Top sheet 3 Back sheet (moisture permeable sheet) 4 Absorber 5 Outer nonwoven fabric 51 Fastening part 6 Solid gather 61 Water-repellent nonwoven fabric 62 Free edge 63 Solid gather elastic member 7 Leg gather 71 Leg elasticity Member 8 Waist part 81 Waist elastic member 10 Foam material A Abdominal side B Back side

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) A61F 13/15 A41B 13/02 B B32B 5/18 A61F 13/18 331 7/02 101 27/40 (72 ) Inventor Mikio Suzuki 2606 Kabane-cho, Akaga-cho, Haga-gun, Tochigi Pref. In the Kao Corporation Research Laboratory (72) Inventor Masao Kurahashi 2606 Kaiga-cho, Akabane-cho, Haga-gun, Tochigi Pref. BD15 BD22 4C003 AA21 4C098 AA09 CC03 DD03 DD05 DD23 4F100 AA08H AA21H AK03 AK04 AK07 AK51C AK63 AR00A AR00B BA02 BA03 BA07 BA10A BA10B BA25C CA07 CA23 DJ01C GB72 HB00B JA13C JD04JD00B

Claims (4)

[Claims] 1. An absorbent article having a liquid-retentive absorbing layer and a liquid-impermeable leakproof layer, wherein the leakproof layer has an ultraviolet transmittance of 10% or less, a whiteness of 65 or more, and total light transmission. An absorbent article comprising a sheet material having a percentage of 35% or less. 2. The sheet material has a moisture permeability of 1 kg / kg.
The absorbent article according to claim 1, wherein the water resistant pressure is 4.9 kPa or more (m ² · 24 hr) or more. 3. A urethane foam is disposed between the absorbing layer and the leak-proof layer, wherein the urethane foam is
Density is 5 to 35 kg / m ³ , no load thickness is 1 to 1
0 mm, compression recovery rate (b / a) [a; thickness after urethane foam was left for 24 hours (thickness before compression)
(Mm), b; After compression for 24 hours at a pressure of 17.6 kPa, the pressure was removed and the thickness when left for 30 minutes (m
m)] is 60% or more. 4. An absorbent article having a liquid-retentive absorbing layer and a liquid-impermeable leakproof layer, wherein urethane foam is arranged between the absorbent layer and the leakproof layer, and A sheet material is disposed between the layer and the urethane foam, wherein the urethane foam has a density of 5 to 35 kg / m ³ ,
No-load thickness: 1 to 10 mm, compression recovery rate (b / a)
[A: thickness after urethane foam was left for 24 hours (thickness before compression) (mm); b: thickness after pressing at 17.6 kPa for 24 hours, removing the pressure and leaving for 30 minutes (mm) ] The sheet material has an ultraviolet transmittance of 10% or less, a whiteness of 65 or more, and a total light transmittance of 35% or less.