JP2015030836A - Foam adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foam adhesive sheet preventing float or peeling from being generated under a low temperature environment, excellent in moisture permeability, capable of appropriately holding a moisture content, having no coloring, hardly causing impression and not bleeding vaseline etc., during storage.SOLUTION: The foam adhesive sheet includes an adhesive layer and a base material sheet. The adhesive layer having a density of 0.3-0.67 g/cmis formed from a hot melt type adhesive including each specific amount of a styrene based elastomer (A) mainly made of a styrene isoprene styrene block copolymer, a tackifier resin (B) mainly made of a hydrogenated terpene resin and a softener (C) mainly made of vaseline.

Description

  The present invention relates to a foamed adhesive sheet that can be applied to the skin.

  Conventionally, adhesive materials that are directly attached to the skin, such as compresses, have been used. This patch can, for example, allow the medicinal component to directly reach the affected area or the like by adhering the medicinal component to the skin after adsorbing the medicinal component into the base material or the adhesive layer.

Patent Document 1 discloses a laminate comprising a pressure-sensitive adhesive composition containing a styrene block copolymer (A), a mineral oil softener (B), and a tackifier (C). It is disclosed that it is suitable for sticking (claims 1, 3, [0001]). And the laminated body which made the foaming density 0.2 (g / cm < ³ >) of the pressure sensitive adhesive layer using the pressure sensitive adhesive composition which further contains petrolatum as a moisturizer is disclosed ([0060]). Table 1, [0064], [0065]).

Moreover, in patent document 2, the laminated body using the resin composition containing fats and oils (A), a styrene-type block copolymer (B), and a tackifier (C) is suitable for sticking to skin. There is a disclosure (claims 1, 4, [0001]). And the sheet | seat which foamed the resin layer using the resin composition containing petrolatum as the said fats and oils (A) is disclosed (Claims 3 and 5). Specifically, the foam density of 0.7 ( g / cm ³ ) laminates are disclosed.

JP 2011-236379 A JP2013-013705A

  However, since the laminate disclosed in Patent Document 1 uses a pressure-sensitive adhesive composition containing a large amount of the mineral oil softener (B), petrolatum may bleed on the surface, which can be stored for a long time. It was not suitable. Moreover, since the laminated body disclosed in Patent Document 1 has a relatively low density of the pressure-sensitive adhesive layer, the moisture permeability is good, but an indentation is made with a light pressure that can be pressed by hand. It was. Moreover, the moisture of the skin was not kept after sticking.

Further, the sheet disclosed in Patent Document 2 can be kept moist by petrolatum, but the density of the resin layer is relatively high, so that the moisture permeability becomes poor and the balance between moisture permeability and moisture cannot be achieved.
In the case of the sheet disclosed in Patent Document 2, as the styrene block copolymer, a copolymer other than the styrene-isoprene-styrene block copolymer (hereinafter referred to as “other copolymer”) is mainly used. use. When the “other copolymer” was used, the adhesion at low temperature was insufficient or it was easy to color. Furthermore, when the “other copolymer” and the styrene-isoprene-styrene block copolymer are used in combination, the vaseline bleeds on the surface because the compatibility between the “other copolymer” and the petrolatum is poor. It was not suitable for long-term preservation.

  The present invention does not float or peel even in a low-temperature environment during sticking, has excellent moisture permeability and can keep the amount of water moderately, has no coloration, is not easily indented, and bleeds petrolatum etc. during storage An object of the present invention is to provide a foamed pressure-sensitive adhesive sheet.

The present invention is a foamed pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer and a substrate sheet,
The pressure-sensitive adhesive layer has a density of 0.3 to 0.67 (g / cm ³ ),
The hot-melt type in which the pressure-sensitive adhesive layer contains a styrene-based elastomer (A): 15 to 35% by weight, a tackifier resin (B): 25 to 45% by weight, and a softening agent (C): 25 to 50% by weight. A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive (provided that the total of (A) to (C) is 100% by weight);
80% to 100% by weight of a styrene-isoprene-styrene block copolymer is contained in 100% by weight of the styrene elastomer (A),
80% to 100% by weight of hydrogenated terpene resin in 100% by weight of the tackifying resin (B),
Containing 80 to 100% by weight of petrolatum in 100% by weight of the softener (C),
The present invention relates to a foamed adhesive sheet.

  According to the present invention, no sticking or peeling occurs even in a low-temperature environment during sticking, it is excellent in moisture permeability and can keep the amount of water moderately, there is no coloring, it is hard to be indented, and petrolatum etc. bleeds during storage It was possible to provide a foamed pressure-sensitive adhesive sheet.

The styrenic elastomer (A) used in the present invention will be described.
The styrene elastomer (A) preferably has a triblock structure from the viewpoint of cohesive strength.
Styrenic elastomer (A) is a styrene-isoprene-styrene block copolymer (hereinafter abbreviated as “SIS”) in 100% by weight of styrene elastomer (A) from the viewpoint of adhesion and bleeding. It is important to contain it in an amount of 85 to 100% by weight. In SIS, the styrene part is a cohesive unit, and the part other than styrene is a relaxation unit.
SIS may be carboxyl-modified. The styrene block may contain a copolymer of styrene and another aromatic vinyl compound such as α-methylstyrene.
SIS can be used alone or in combination of two or more.

As the styrene elastomer (A), “other styrene elastomer” other than SIS can be used.
Other styrene-based elastomers preferably have a triblock structure having a cohesive unit derived from styrene and a relaxation unit derived from components other than styrene, as in SIS.
Other styrene-based elastomers include, for example, a styrene-butadiene-styrene block copolymer (hereinafter abbreviated as “SBS”) and a hydrogenated product of a styrene-butadiene-styrene block copolymer (hereinafter referred to as “SEBS”). Abbreviated), hydrogenated styrene-isoprene-styrene block copolymer (hereinafter also abbreviated as “SEPS”), styrene-butadiene-isoprene-styrene block copolymer (hereinafter also abbreviated as “SBIS”), Examples thereof include hydrogenated products of styrene-butadiene-isoprene-styrene block copolymers (hereinafter also abbreviated as “SEEPS”).
These copolymers may be carboxyl-modified. The styrene block may contain a copolymer of styrene and another aromatic vinyl compound such as α-methylstyrene.
These other styrenic elastomers can be used alone or in combination of two or more.

The styrene elastomer (A) may contain a diblock structure in addition to the triblock structure. Tack improves more by having a diblock structure.
The proportion of the diblock structure is preferably 5% or more from the viewpoint of improving tack and is preferably 70% or less in terms of cohesive strength. It should be noted that the diblock structure can be used even if it is not included.

  In the styrene elastomer (A), the ratio of styrene which is a cohesive force unit is preferably 10 to 65% by weight. By including the ratio of styrene within the above range, the cohesive force can be adjusted appropriately.

  The melt flow rate (also referred to as MFR) of the styrene elastomer (A) is preferably 1 (g / 10 minutes) or more and 100 (g / 10 minutes) or less. When the MFR is within the above range, the foamed pressure-sensitive adhesive sheet can easily be lifted, peeled off and easily peeled off. The melt flow rate is one of the measures showing the fluidity of a resin in a molten state, and is measured under conditions of 190 ° C. and 2.16 kg in accordance with JIS K7210.

The tackifying resin (B) preferably has a softening point of 75 to 160 ° C.
When the softening point is within the above range, it is easy to achieve both suppression of floating / peeling of the foamed pressure-sensitive adhesive sheet and ease of peeling.
In the present invention, the softening point is a temperature determined by a method defined in JIS K 6863. That is, a specified ring is filled with a tackifying resin (B), placed in a heating medium and held horizontally, a specified sphere is placed in the center of the tackifying resin (B), and the temperature of the heating medium at a constant rate. Is the temperature when the ball sinks due to the softening of the tackifying resin (B) and touches the bottom plate of the ring base.

Examples of tackifying resins include hydrogenated terpene resins, rosin resins, hydrogenated rosin resins, terpene resins, hydrocarbon resins, hydrogenated hydrocarbon resins, epoxy resins, Hydrogenated epoxy resin, polyamide resin, hydrogenated polyamide resin, elastomeric resin, hydrogenated elastomeric resin, phenolic resin, hydrogenated phenolic resin, ketone resin, hydrogenated Ketone-based resins, petroleum-based resins, hydrogenated petroleum-based resins, styrene-based resins and hydrogenated styrene-based resins. These tackifying resins can be used alone or in combination of two or more.
Among these, from the viewpoint of hue, a hydrogenated terpene resin is preferable. By adding hydrogen, the ring structure in the molecule does not have a conjugated double bond, so that not only is it difficult to color when heated and melted, but the foamed adhesive tape is used in an environment where the room temperature rises to about 40 ° C in the summer, for example. Even when stored, the foamed pressure-sensitive adhesive layer becomes difficult to color over time.
In the present invention, as the tackifying resin (B), various tackifying resins described above can be used in addition to the hydrogenated terpene resin, but hydrogenated in 100% by weight of the tackifying resin (B). It is important to contain 80 to 100% of the terpene resin, preferably 85 to 100% by weight.

As a softener, for example, petrolatum, mineral oil, vegetable oil, animal oil and the like can be fried.
As mineral oil, liquid paraffin, paraffin, paraffinic mineral oil in which the number of paraffin chain carbon accounts for 50% or more of the total number of carbons, naphthenic mineral oil in which the number of naphthenic ring carbons accounts for 30 to 40% by weight of the total number of carbons, In addition, it is possible to fry aromatic mineral oil or the like in which the aromatic carbon number occupies 30% by weight or more of the total carbon number.
Vegetable oils: Olive oil, carnauba wax, rice germ oil, corn oil, sasanqua oil, camellia oil, castor oil, jojoba seed oil, mink oil, eucalyptus leaf oil, and the like.
Animal fats: Can fry beeswax, squalane, honey.
Others, mistylic acid, oleic acid, isopropyl myristate, zinc myristate, octyldodecyl myristate, glyceryl triisooctanoate, octyldodecanol, hexyldecanol, diisopropyl adipate, diethyl sebacate, stearic acid, isostearic acid, crotamiton, medium chain Fatty acid triglycerides, ethylene glycol salicylate, cetyl ethylhexanoate, glycol distearate, cetearyl alcohol, cetanol, cetyl palmitate, ethylhexyl palmitate, isopropyl palmitate, behenyl alcohol and the like can also be mentioned.
These softeners can be used alone or in combination of two or more.
In the present invention, the above-mentioned various softeners can be used as the softener (C) in addition to petrolatum, but 80% to 100% petrolatum is contained in 100% by weight of the softener (C) from the viewpoint of moisture retention. Is important, and preferably 85 to 100% by weight.

  The viscosity of the softening agent (C) is preferably 10 to 10,000 mPa · s at 50 ° C. When the viscosity is within the above range, it is easy to achieve both suppression of floating / peeling of the foamed pressure-sensitive adhesive sheet and ease of peeling. The viscosity is a value measured using a B-type viscometer (measurement conditions are 50 ° C., rotor No. 3, 12 rpm, 30 seconds).

The molecular weight of the softener (C) is preferably 100 to 10,000. When the molecular weight is within the above range, the viscosity at the time of heating in order to apply the hot-melt pressure-sensitive adhesive is likely to decrease, and bleeding out is less likely to occur.
In the present invention, the molecular weight is a weight average molecular weight. In the present invention, the weight average molecular weight is a polystyrene-converted weight average molecular weight obtained by gel permeation chromatography (hereinafter also abbreviated as “GPC”).
The measuring apparatus, column, and molecular weight measuring conditions of GPC are as follows.
Equipment: Prominence made by Shimadzu Corporation
Column: manufactured by TOSOH, TSKgel GMH x 2 connected detector: RID-10A
Solvent: THF (tetrahydrofuran)
Column temperature: 40 ° C
Flow rate: 1 mL / min

The pressure-sensitive adhesive layer constituting the foamed pressure-sensitive adhesive sheet of the present invention comprises the styrenic elastomer (A), the tackifier resin (B) and the softener (C) as follows: (A) :( B) :( C) = 15 to 35:25 to 45:20 to 50 (wt%) in composition, (A) :( B) :( C) = 17 to 33:30 to 40:25 to 45 (wt%) It is preferable to contain by the composition of). However, the total of (A) to (C) is 100% by weight.
The content of the styrene-based elastomer (A) and the tackifier resin (B) mainly affects the balance between suppression of floating / peeling of the foamed pressure-sensitive adhesive sheet and ease of peeling. Further, the content of the softening agent (C) mainly affects the compatibility of coating suitability, productivity and cohesive strength.

  The pressure-sensitive adhesive layer constituting the foamed pressure-sensitive adhesive sheet of the present invention can contain an antioxidant, a fragrance, an extract and the like as optional components.

Examples of the antioxidant include pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxy). Phenyl) propionate, diethyl [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] phosphonate,
4,6-bis (octylthiomethyl) -o-cresol, ethylenebis (oxyethylene) bis [3- (5-t-butyl-4-hydroxy-m-tolyl] propionate,
Examples include tris (2,4-di-t-butylphenyl) phosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, and the like.
The phenolic antioxidant is preferably pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], and the phosphorus antioxidant is tris (2,4-di-t. -Butylphenyl) phosphite is preferred. These can be used alone or in combination of two or more.

  Examples of the fragrances include herbal oils or extracts such as rose, pinene, limonene, eucalyptus, lavender and orange, lower alcohols and aldehydes. These can be used alone or in combination of two or more.

  Examples of the extract include orange extract, Sasa extract, rose extract, eucalyptus extract, lavender extract, and the like. These can be used alone or in combination of two or more.

  Since the blending amount of the above-mentioned arbitrary components varies depending on the effect, the lower limit value cannot be limited. However, the upper limit is preferably 20 parts by weight or less, more preferably 18 parts by weight or less, with respect to the total of 100 parts by weight of (A) to (C). Adhesion to the skin is maintained when the blending amount is 20 parts by weight or less. Bleeding out of optional components is less likely to occur.

  The foamed pressure-sensitive adhesive sheet of the present invention comprises a styrenic elastomer (A), a tackifier resin (B), a softener (C), and other optional components used as necessary, a roll, a Banbury mixer, a kneader, and a stirrer. Heated melt type (hot melt type) pressure-sensitive adhesive prepared by heating and mixing using a melting pot provided, or a uniaxial or biaxial extruder, or a solvent-type pressure sensitive adhesive obtained by dissolving in an appropriate solvent and stirring and mixing. Can be used. The adhesive used is preferably a hot-melt adhesive that does not use a solvent.

  The hot melt pressure-sensitive adhesive preferably has a viscosity at 140 ° C. of 500 to 50000 mPa · s. The viscosity is a value measured using a B-type viscometer (measurement conditions are 140 ° C., rotor No. 3, 12 rpm, 30 seconds).

The foamed pressure-sensitive adhesive sheet of the present invention has a base sheet and a pressure-sensitive adhesive layer. It is important that the pressure-sensitive adhesive layer contains bubbles, and the degree of bubble inclusion can be specified by density. The density of the adhesive layer is important to be 0.3~0.67 (g / cm ^3), further preferably 0.35~0.65g / cm ^3.
When the density is within the above range, indentation is difficult to be caused, floating and peeling are less likely to occur, moisture permeability is excellent, and “familiarity” or adhesion to the skin is further improved.
In addition, the form of the bubbles contained in the foamed adhesive layer is not limited as long as the object of the present invention can be achieved, and closed cells, open cells, or closed cells and open cells may be mixed.

  The foamed pressure-sensitive adhesive layer is formed by introducing a hot-melt pressure-sensitive adhesive into a mixer and bringing it into a uniform molten state at a temperature of, for example, 60 to 250 ° C., and in this state, physical foaming (for example, bubbling) or chemical foaming Thus, the pressure-sensitive adhesive can be applied to the substrate or the peelable sheet. In the foaming method of the present invention, physical foaming is more preferable when the interaction between the foaming agent and the medicinal component is concerned.

Chemical foaming is a method in which an inorganic foaming agent or an organic foaming agent or a mixture thereof is mixed with a hot-melt adhesive, and nitrogen gas or carbon dioxide gas generated during the decomposition reaction is used.
In the physical foaming, air, carbon dioxide gas, nitrogen gas, argon gas, helium gas or the like is mixed in a liquid mixture, which is a hot melt adhesive, under heat and pressure, and then foamed under atmospheric pressure. At this time, foaming of the hot melt pressure-sensitive adhesive may be any one of closed cells, open cells, and a mixture of closed cells and open cells.

  As for the thickness of a foaming adhesive layer, 1-2000 micrometers is preferable.

  The foamed pressure-sensitive adhesive layer can also be crosslinked by heating or ultraviolet irradiation.

The base material sheet which comprises the foaming adhesive sheet | seat of this invention is demonstrated.
Base sheet is, for example, polyester resin, polycarbonate resin, polyarylate resin, acrylic resin, polyphenylene sulfide resin, polystyrene resin, vinyl resin, vinyl chloride resin, polyimide resin, epoxy resin, polyethylene In addition to resin sheets formed from resins such as polyolefin resins such as polypropylene and poolinorbornene, non-woven fabrics, woven fabrics, cloths, paper, glass, metal foils, metal meshes and the like and composites containing these are mentioned. .
Further, the base sheet may be subjected to easy adhesion treatment such as corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, antistatic treatment, coloring treatment, and the like, if necessary.
Or the peelable sheet formed by carrying out the peeling process of the said various resin sheet surface and paper surface can also be used as a base material sheet.
Although there is no restriction | limiting in particular in the thickness of a base material sheet, 1-1000 micrometers is preferable.

Examples of the foamed pressure-sensitive adhesive sheet of the present invention include the following modes.
・ [Release sheet / foaming adhesive layer / release sheet],
・ [Base sheet not subjected to release treatment / foamed adhesive layer / release sheet)],
-[Releasable sheet / foamed pressure-sensitive adhesive layer / core material (base material sheet) not subjected to release treatment / foamed pressure-sensitive adhesive layer / releasable sheet].

  The foamed adhesive sheet of the present invention is, for example, general medical applications such as adhesive plaster, surgical tape, electrocardiographic electrode fixing sheet, compressing foam adhesive sheet, adhesive bandage, injection needle fixing sheet, magnetic particle fixing sheet, etc. Or it is also preferable to use fats and oils or fine powder for the industrial adhesive tape of the objective which discharge | releases to a to-be-adhered body gradually.

  EXAMPLES Hereinafter, the present invention will be described specifically and in detail with reference to examples. However, these examples are only one aspect of the present invention, and the present invention is not limited to these examples. In the examples, “part” means “part by weight” and “%” means “% by weight”.

(Production Examples 1 to 34)
The raw materials described in Table 1 were put into a kneader equipped with a stirrer according to the composition shown in Table 2, and stirred at 140 ° C. under reduced pressure until uniform, to obtain an adhesive. The degree of coloring was evaluated according to the method described later, and the results are shown in Table 2.

(Examples 1-17, Comparative Examples 1-17)
The hot melt pressure-sensitive adhesives obtained in Production Examples 1 to 34 were heated to 130 ° C. and melted, and then blown with nitrogen gas to be foamed. The foamed pressure-sensitive adhesive is coated on a non-woven fabric having a thickness of 100 μm, a release sheet is bonded onto the foamed pressure-sensitive adhesive layer, and a foamed pressure-sensitive adhesive sheet having a configuration of “nonwoven fabric / foamed pressure-sensitive adhesive layer / releasable sheet” is obtained. The density, moisture permeability, skin moisture content change, indentation, bleed and adhesion were evaluated according to the method described below, and the results are shown in Table 2.
The thickness of the foamed pressure-sensitive adhesive layer was as shown in Table 2, and the density of the resulting foamed pressure-sensitive adhesive layer was adjusted by the amount of nitrogen gas blown.

[density]
The weight W1 (g) of the 10 cm × 10 cm foamed adhesive sheet and the total weight W2 (g) of the 10 cm × 10 cm non-woven fabric and the peelable sheet were measured, and the density was determined by the following formula. The volume of the foamed pressure-sensitive adhesive layer is determined from the area of 10 cm × 10 cm and the thickness of the pressure-sensitive adhesive layer shown in Table 2.
Density (g / cm ³ ) = (W1-W2) / Volume of foamed adhesive layer

[Coloring]
After each component of (A) to (C) was dissolved in xylene at a constant temperature (23 ° C.) and a constant humidity (65%) so as to have the same composition as each production example, a uniform solution was obtained, The sample was removed under reduced pressure at 80 ° C. as a blank, and the color of the pressure-sensitive adhesive of each production example was confirmed visually and with a spectrocolorimeter. The numerical value was the average of the values measured five times.
[Criteria]
(Double-circle): Coloring was not seen visually and the difference of the value of b * compared with the blank was 2 or less.
○: Some coloration was visually observed, and the value of b * compared to the blank was 2 or more and 5 or less.
X: Coloring was clearly seen visually, and the value of b * compared with the blank was 5 or more.
◎ and ○ are judged to be usable.

[Moisture permeability]
A moisture absorbent was placed in a container having a moisture permeable area of 30 cm ² and a height of 1.5 cm, and a foamed adhesive sheet having a configuration of “nonwoven fabric / adhesive layer / release sheet” was prepared, and the release sheet was peeled off. Thereafter, the upper surface of the container was closed with a foamed adhesive sheet, the periphery was fixed with wax, and this was left in a constant temperature (40 ° C.) and constant humidity (90%) for 24 hours. Subsequently, the amount of water increase in the moisture absorbent in the container was measured, and the amount of absorbed water was converted into [g / m ² · 24 hr] and displayed.
[Criteria]
A: The moisture permeability was 400 to 500 g / m ² · 24 hr.
○: Moisture permeability was 200 to 400 g / m ² · less than 24 hr.
Δ: Moisture permeability was 10 to 200 g / m ² · less than 24 hr.
X: The moisture permeability was less than 10 g / m ² · 24 hr.
Note that ◎, ○, and △ are judged to be usable.

[Change in skin moisture]
After measuring the moisture content of the back of the hand with a moisture meter, the release sheet was peeled off from the foamed adhesive sheet cut to a length of 100 mm and a width of 50 mm, and a nonwoven fabric with a foamed adhesive layer was pasted on the back of the hand. One hour after sticking, the nonwoven fabric with foamed adhesive layer was peeled off, and immediately after peeling and 5 minutes later, the moisture content of the portion where the nonwoven fabric with foamed adhesive layer was pasted was measured with a moisture meter, and the foamed adhesive layer It compared with the moisture content before sticking an attached nonwoven fabric. The numerical value was the average of the values measured three times.
[Criteria]
(Double-circle): The moisture content of the part which stuck the nonwoven fabric with a foaming adhesive layer rose 10% or more compared with before sticking a nonwoven fabric with a foaming adhesive layer.
○: The moisture content of the portion where the non-woven fabric with the foam pressure-sensitive adhesive layer was affixed increased by 5% or more and less than 10% compared to before the non-woven fabric with the foam pressure-sensitive adhesive layer was applied.
(Triangle | delta): Compared with before sticking a nonwoven fabric with a foaming adhesive layer, the moisture content of the part which stuck the nonwoven fabric with a foaming adhesive layer remained in the range of +/- 2% almost unchanged.
X: The moisture content of the portion where the non-woven fabric with the foam pressure-sensitive adhesive layer was applied was 5% or more lower than before the non-woven fabric with the foam pressure-sensitive adhesive layer was applied.
Note that ◎ and ○ are judged to be usable.

[Indentation]
Peeling the peelable Sea foamed pressure-sensitive adhesive sheet cut into 10cm square, a foamed pressure-sensitive adhesive layer-attached nonwoven as blowing adhesive layer is in contact with the glass plate placed on a glass plate, an area of 5 cm ² of nonwoven side, 1 kg / Pressure was applied at cm ² for 30 seconds to confirm the formation of indentations.
[Criteria]
○: Almost no indentation remained on the surface of the nonwoven fabric.
X: The indentation remained clearly on the surface of the nonwoven fabric, and was not usable.

[Bleed]
The peelable sheet was peeled off from the foamed adhesive sheet cut into 5 cm squares, and then the high quality paper cut into 5 cm squares was bonded to the foamed adhesive layer so as not to protrude and pressed once by a 2 kg roller. After 24 hours, bleeding on fine paper was confirmed.
[Criteria]
(Double-circle): The bleed | bleed to 5 cm square quality paper is less than 5% of the whole area, and it can be used.
◯: The bleed to 5 cm square high quality paper is less than 20% of the total area and can be used.
X: Bleed is found on the whole high-quality paper (area 100%) and cannot be used.
◎ and ○ are judged to be usable.

[Adhesion]
The peelable sheet was peeled off from the foamed adhesive sheet cut to a length of 100 mm and a width of 25 mm, the foamed adhesive layer nonwoven fabric was affixed to the artificial skin, and pressure-bonded by reciprocating a 1 kg roller. After 3 hours at a temperature of 23 ° C. and a relative humidity of 65%, after standing for 1 hour at a temperature of 5 ° C. and a relative humidity of 65%, or after standing for another hour at a temperature of 23 ° C. and a relative humidity of 65%, The peel strength when the foamed adhesive layer nonwoven fabric was peeled off from the artificial skin under the environment was measured. The peel strength with a width of 25 mm was measured under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees, and the average value of the values measured five times (N / 25 mm). Whether the peeled state was cohesive failure or interfacial peeling was visually confirmed on the pressure-sensitive adhesive layer after peeling.
[Criteria]
(Double-circle): Peeling strength was 5N or more and 7N or less, the adhesive state did not remain at the time of peeling, and the peeling state was interface peeling.
○: The peel strength was 2N or more and less than 5N, and the pressure-sensitive adhesive did not remain at the time of peeling, and the peeled state was interfacial peeling.
X: The peel strength was less than 2N, or 7N or more, or the adhesive remained, and the peeled state was cohesive failure.
Note that ◎ and ○ are judged to be usable.

[Coloring over time]
The foamed adhesive sheet cut into a 20 cm square was allowed to stand at a temperature of 40 ° C. for 6 months, and further allowed to stand at a temperature of 23 ° C. and a relative humidity of 65% for 1 hour. .
[Criteria]
○: Some coloration was visually observed, and the value of b * compared to the blank was 5 or less.
X: Coloring was clearly seen visually, and the value of b * compared with the blank was 5 or more.
○ is judged to be usable.

As shown in Table 2, since Comparative Example 1 was excessively foamed, the pressure-sensitive adhesive layer was too low in density, indentations remained, and adhesion was insufficient.
On the other hand, Comparative Example 2 in which foaming is insufficient and the density of the pressure-sensitive adhesive layer is large, and Comparative Example 3 in which the pressure-sensitive adhesive layer is not foamed at all have insufficient moisture permeability. Furthermore, in Comparative Example 3, petrolatum tends to bleed on the surface.

Comparative Example 4 is a case where a hydrogenated product (SEPS) of a styrene-isoprene-styrene block copolymer is used instead of a styrene-isoprene-styrene block copolymer as a styrene elastomer, and the adhesion at low temperature is It is insufficient.
Comparative Example 5 is a case in which a styrene-butadiene-styrene block copolymer (SBS) is used as a styrene elastomer instead of a styrene-isoprene-styrene block copolymer, and a uniform adhesive is produced. Since the heating and melting time of is long, it is easy to color.

  The comparative example 6 is a case where mineral oil is used without using petrolatum as a softening agent, and the moisture of the skin is reduced by sticking.

Comparative Example 7 is a case where a petroleum resin is used instead of the hydrogenated terpene resin as the tackifier resin (B), and the adhesion at low temperatures is insufficient.
Comparative Examples 8 and 9 are cases where a rosin resin or a non-hydrogenated terpene resin is used instead of the hydrogenated terpene resin as the tackifier resin (B), respectively, and is easily colored.

Comparative Example 10 is a case where the amount of the hydrogenated terpene resin contained as the tackifier resin (B) is too large, and the adhesiveness at low temperature is excellent, but the adhesiveness near room temperature is inferior.
On the other hand, Comparative Example 11 is a case where the amount of hydrogenated terpene resin is too small, and the adhesion is poor.

Comparative Example 12 is a case where the amount of petrolatum contained as the softening agent (C) is too small, and the moisture content, that is, the moisturizing effect is insufficient.
On the other hand, the comparative example 13 is a case where there is too much amount of petrolatum, and petrolatum is easy to bleed on the surface.

Comparative Example 14 is a case where the amount of the styrene-isoprene-styrene block copolymer contained as the styrene-based elastomer (A) is too large, and the heating and melting time for making a uniform pressure-sensitive adhesive is long. .
On the other hand, Comparative Example 15 is a case where the amount of the styrene-isoprene-styrene block copolymer is too small, and the adhesion is insufficient.

Comparative Example 16 is a case where petrolatum and mineral oil are used in combination as the softening agent (C), but since the amount of petrolatum in the softening agent (C) is too small, the moisture content, that is, the moisturizing effect is insufficient. Not only is it easy to bleed mineral oil and petrolatum on the surface.
Comparative Example 17 is a case where a styrene-isoprene-styrene block copolymer (SIS) and a hydrogenated product of styrene-isoprene-styrene block copolymer (SEPS) are used in combination as the styrene elastomer (A). However, since the amount of SIS in the styrene elastomer (A) is too small, petrolatum is likely to bleed on the surface.

  Compared to these comparative examples, the foamed pressure-sensitive adhesive sheet of the present invention shown in the examples does not float or peel off even in a low temperature environment during sticking, has excellent moisture permeability and can keep the amount of water moderately, There is no coloring, it is hard to get indentation, and petrolatum and the like do not bleed during storage.

Claims (1)

A foamed adhesive sheet comprising an adhesive layer and a substrate sheet,
The pressure-sensitive adhesive layer has a density of 0.3 to 0.67 (g / cm ³ ),
The hot-melt type in which the pressure-sensitive adhesive layer contains a styrene-based elastomer (A): 15 to 35% by weight, a tackifier resin (B): 25 to 45% by weight, and a softening agent (C): 25 to 50% by weight. A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive (provided that the total of (A) to (C) is 100% by weight);
80% to 100% by weight of a styrene-isoprene-styrene block copolymer is contained in 100% by weight of the styrene elastomer (A),
80% to 100% by weight of hydrogenated terpene resin in 100% by weight of the tackifying resin (B),
Containing 80 to 100% by weight of petrolatum in 100% by weight of the softener (C),
Foam adhesive sheet.