|
Patent Abstract
A pressure-sensitive adhesive sheet for skin adhesion in which an
adhesive force of the pressure-sensitive adhesive on the backing
film does not lower greatly even with the lapse of long term and
the initial adhesive force is substantially maintained, and a first-aid
adhesive plaster using the same are disclosed. The pressure-sensitive
adhesive sheet for skin adhesion comprises a backing film and a
pressure-sensitive adhesive layer for skin adhesion formed on one
side of the backing film, wherein the backing film comprises about
40 to about 70 parts by weight of a polyester plasticizer having
a number average molecular weight of about 1,500 to about 3,000,
an appropriate amount of a stabilizer comprising at least one metallic
soap selected from the group consisting of fatty acid calcium, fatty
acid zinc and fatty acid barium, and about 0.1 to about 1.0 part
by weight of hydrotalcite per 100 parts by weight of a vinyl chloride
polymer.
Patent Claims
What is claimed is:
1. A pressure-sensitive adhesive sheet for skin adhesion, comprising
a backing film and a pressure-sensitive adhesive layer for skin
adhesion formed on one side of the backing film, wherein the backing
film comprises: 100 parts by weight of a vinyl chloride polymer;
about 40 to about 70 parts by weight of a polyester plasticizer
having a number average molecular weight of about 1,500 to about
3,000; a stabilizing effective amount of a stabilizer comprising
at least one metallic soap selected from the group consisting of
fatty acid calcium, fatty acid zinc and fatty acid barium; and about
0.1 to about 1.0 part by weight of hydrotalcite.
2. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the vinyl chloride polymer is at least one polymer
selected from a polymer of vinyl chloride alone and copolymers of
vinyl chloride and an ethylenically unsaturated hydrocarbon having
2 to 4 carbon atoms.
3. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 2, wherein the vinyl chloride polymer is at lest one polymer
selected from the group consisting of polyvinyl chloride and vinyl
chloride/ethylene copolymers and vinyl chloride/vinyl acetate copolymer.
4. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the vinyl chloride polymer has an average degree
of polymerization of about 500 to about 1,500.
5. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the polyester plasticizer comprises a polyester
obtained from an aliphatic or aromatic dicarboxylic acid having
2 to 10 carbon atoms and a glycol having 2 to 10 carbon atoms.
6. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the polyester has a number average molecular
weight of about 1,500 to about 3,000.
7. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the metallic soap is a combination of a fatty
acid calcium and a fatty acid zinc.
8. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 7, wherein the fatty acid in the metallic soap is a saturated
or unsaturated fatty acid having 12 to 10 carbon atoms.
9. The pressure-sensitive adhesive sheet for skin adhesion as claimed
in claim 1, wherein the metallic soap is in an amount of about 0.5
to about 2.5 parts by weight per 100 parts by weight of the vinyl
chloride polymer.
10. The pressure-sensitive adhesive sheet for skin adhesion as
claimed in claim 1, wherein the pressure-sensitive adhesive is an
acrylic pressure-sensitive adhesive.
11. The pressure-sensitive adhesive sheet for skin adhesion as
claimed in claim 10, wherein the acrylic pressure-sensitive adhesive
comprises a polymer comprising an alkyl acrylate having 4 to 12
carbon atoms in the alkyl moiety as a main monomer component.
12. The pressure-sensitive adhesive sheet for skin adhesion as
claimed in claim 11, wherein the acrylic pressure-sensitive adhesive
further comprises at least one vinyl ester selected from the group
consisting of alkyl (meth)acrylates having 1 to 3 carbon atoms in
the alkyl moiety, vinyl acetate and N-methyl-2-pyrrolidone.
13. The pressure-sensitive adhesive sheet for skin adhesion as
claimed in claim 11, wherein the acrylic pressure-sensitive adhesive
comprises an acrylic pressure-sensitive adhesive that contains at
least one of a hydroxyl group and a carboxyl group.
14. The pressure-sensitive adhesive sheet for skin adhesion as
claimed in claim 13, wherein the acrylic pressure-sensitive adhesive
comprises a copolymer comprising an alkyl acrylate ester as a main
monomer component and an hydroxyalkyl (meth) acrylate or (meth)acrylic
acid as a comonomer copolymerizable therewith.
15. A first-aid adhesive plaster comprising a pressure-sensitive
adhesive sheet for skin adhesion as claimed in claim 1, and an absorbent
pad provided on a central region on a surface of the pressure-sensitive
adhesive layer.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a pressure-sensitive adhesive
sheet for skin adhesion comprising a backing film comprising a flexible
vinyl chloride resin, and a pressure-sensitive adhesive layer provided
on one side of the backing film, and its use. More particularly,
the invention relates to a pressure-sensitive adhesive sheet for
skin adhesion that an adhesive force of the pressure-sensitive adhesive
on the backing film does not lower greatly even with the lapse of
long term and substantially maintains the initial adhesive force,
and to its use, for example, a use as a first-aid adhesive plaster.
[0003] 2. Description of the Related Art
[0004] Conventionally, a pressure-sensitive adhesive sheet for
skin adhesion comprising a flexible backing film having provided
thereon a pressure-sensitive adhesive layer has been used as a dressing,
a bandage or the like, and has also been widely used in homes as
a first-aid adhesive plaster by providing an absorbent pad such
as gauze at a central region on a surface of the pressure-sensitive
layer. Further, an adhesive drug sheet for skin adhesion comprising
a backing film having provided thereon a layer comprising a pressure-sensitive
adhesive containing various drugs is used for various medical uses.
Conventionally, a film comprising a so-called flexible vinyl chloride
resin has widely been used as the backing film for such a pressure-sensitive
adhesive sheet for skin adhesion from the points that it is flexible,
has good adaptability to skin, and has excellent printability. In
such a flexible vinyl chloride resin, a combination of a fatty acid
calcium-fatty acid zinc type stabilizer and an epoxidized soybean
oil has generally been used as a stabilizer from the standpoint
of safety. However, when an acrylic pressure-sensitive adhesive,
for example, is coated on a backing film comprising such a vinyl
chloride resin to prepare an adhesive plaster, an adhesive force
of the backing film decreases with the passage of time. Thus, where
the adhesive force of the pressure-sensitive adhesive decreases,
even if the adhesive plaster is adhered to a skin, an edge of the
adhesive plaster lifts from the skin, and in some cases, the adhesive
plaster peels off from the skin. As a result, the adhesive plaster
may not exhibit the function as a first-aid adhesive plaster.
SUMMARY OF THE INVENTION
[0005] As a result of extensive investigations to overcome those
problems in the conventional pressure-sensitive adhesive sheet for
skin adhesion using a vinyl chloride resin film as a backing film,
the inventors have found that in the conventional vinyl chloride
resin film, an epoxidized soybean oil compounded as a plasticizer
migrates from the backing film to the pressure-sensitive adhesive
layer with the passage of time, thereby crosslinking or curing an
acrylic pressure-sensitive adhesive, for example, and as a result,
the pressure-sensitive adhesive loses its initial adhesive force,
so that the adhesive force lowers with the passage of time.
[0006] Based on the above-described finding, the inventors also
have made further investigation and found that when a polyester
plasticizer is used as a plasticizer in place of the epoxidized
soybean oil, and a combination of a metallic soap and a hydrotalcite
is used as a stabilizer, a film produced by calendering has an excellent
heat stability, and also found that when the film thus obtained
is used as the backing film, and a pressure-sensitive adhesive is
applied to one side of the backing film to form a pressure-sensitive
adhesive sheet for skin adhesion, the plasticizer does not migrate
into the pressure-sensitive adhesive layer, and the pressure-sensitive
adhesive sheet for skin adhesion can substantially maintain the
initial adhesive force even with the lapse of long term. The present
invention has been completed based on this finding.
[0007] Accordingly, one object of the present invention is to provide
a pressure-sensitive adhesive sheet for skin adhesion including
a backing film that has an excellent heat stability during its production
by calendering and a pressure-sensitive adhesive layer coated on
one side of the backing film, a pressure-sensitive adhesive in the
adhesive layer does not lose adhesive force greatly so that the
initial adhesive force is substantially maintained.
[0008] Another object of the present invention is to provide a
first-aid adhesive plaster using the pressure-sensitive adhesive
sheet for skin adhesion.
[0009] According to a first aspect, the present invention provides
a pressure-sensitive adhesive sheet for skin adhesion, which comprises
a backing film and a pressure-sensitive adhesive layer for skin
adhesion formed on one side of the backing film, wherein the backing
film comprises: 100 parts by weight of a vinyl chloride polymer;
about 40 to about 70 parts by weight of a polyester plasticizer
having a number average molecular weight of about 1,500 to about
3,000; a stabilizing effective amount of a stabilizer comprising
at least one metallic soap selected from the group consisting of
fatty acid calcium, fatty acid zinc and fatty acid barium; and about
0.1 to about 1.0 part by weight of hydrotalcite.
[0010] Here, the vinyl chloride polymer may be at least one polymer
selected from a polymer of vinyl chloride alone and copolymers of
vinyl chloride and an ethylenically unsaturated hydrocarbon having
2 to 4 carbon atoms.
[0011] The vinyl chloride polymer may be at lest one polymer selected
from the group consisting of polyvinyl chloride and vinyl chloride/ethylene
copolymers and vinyl chloride/vinyl acetate copolymer.
[0012] The vinyl chloride polymer may preferably have an average
degree of polymerization of about 500 to about 1,500.
[0013] The polyester plasticizer may comprise a polyester obtained
from an aliphatic or aromatic dicarboxylic acid having 2 to 10 carbon
atoms and a glycol having 2 to 10 carbon atoms.
[0014] The polyester may preferably have a number average molecular
weight of about 1,500 to about 3,000.
[0015] The metallic soap may preferably be a combination of a fatty
acid calcium and a fatty acid zinc.
[0016] The fatty acid in the metallic soap may be a saturated or
unsaturated fatty acid having 12 to 20 carbon atoms.
[0017] The metallic soap may be in an amount of about 0.5 to about
2.5 parts by weight per 100 parts by weight of the vinyl chloride
polymer.
[0018] The pressure-sensitive adhesive may preferably be an acrylic
pressure-sensitive adhesive.
[0019] The acrylic pressure-sensitive adhesive may comprise a polymer
comprising an alkyl acrylate having 4 to 12 carbon atoms in the
alkyl moiety as a main monomer component.
[0020] The acrylic pressure-sensitive adhesive may further comprise
at least one vinyl ester selected from the group consisting of alkyl
(meth)acrylates having 1 to 3 carbon atoms in the alkyl moiety,
vinyl acetate and N-methyl-2-pyrrolidone.
[0021] The acrylic pressure-sensitive adhesive may preferably comprise
an acrylic pressure-sensitive adhesive that contains at least one
of a hydroxyl group and a carboxyl group.
[0022] The acrylic pressure-sensitive adhesive may comprise a copolymer
comprising an alkyl acrylate ester as a main monomer component and
an hydroxyalkyl (meth) acrylate or (meth) acrylic acid as a comonomer
copolymerizable therewith.
[0023] According to a second aspect, the present invention provides
a first-aid adhesive plaster comprising the above-mentioned pressure-sensitive
adhesive sheet for skin adhesion and an absorbent pad provided on
a central region on a surface of the pressure-sensitive adhesive
layer.
[0024] As described above, the pressure-sensitive adhesive sheet
for skin adhesion according to the present invention comprises a
backing film comprising a flexible vinyl chloride resin having compounded
therewith a polyester plasticizer as a plasticizer, and hydrotalcite
together with a metallic soap as a stabilizer, and a pressure-sensitive
adhesive layer provided on one side of the backing film, and also
the first-aid adhesive plaster of the present invention uses such
a pressure-sensitive adhesive sheet for skin adhesion, so that the
pressure-sensitive adhesive does not show a great decrease in adhesive
force even after the lapse of long time, and substantially maintains
the initial adhesive force.
[0025] Other objects and advantages of the present invention will
become apparent from the detailed description to follow taken in
conjunction with the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0026] The present invention is described in detailed below.
[0027] The vinyl chloride polymer that can be used in the present
invention includes a homopolymer of vinyl chloride, i.e., polyvinyl
chloride, and copolymers of vinyl chloride and various comonomers.
Examples of the comonomer include ethylenically unsaturated hydrocarbons
having 2 to 4 carbon atoms, such as ethylene, propylene, vinyl acetate,
acrylic acid, acrylic acid ester, methacrylic acid, methacrylic
acid ester, maleic acid, fumaric acid, acrylonitrile, vinylidene
chloride, styrene, etc. The alkyl moiety in the acrylic acid esters
and methacrylic acid esters have 1 to 10 carbon atoms and specific
examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl,
octyl, nonyl, decyl, etc. Those comonomers can be used alone or
as mixtures of two or more thereof. Preferred examples of the vinyl
chloride polymer used in the present invention include polyvinyl
chloride, vinyl chloride/ethylene copolymer, and vinyl chloride/vinyl
acetate copolymer. Of those, polyvinyl chloride is more preferably
used in the present invention. In general, those vinyl chloride
polymers have an average degree of polymerization of about 500 to
about 1,500, and preferably about 700 to about 1,300. If the average
degree of polymerization is less than about 500, mechanical strength
is insufficient while with an average degree of polymerization of
exceeding about 1,500, the compatibility with plasticizers tends
to be decreased.
[0028] A plasticizer, a stabilizer and the like are compounded
with the vinyl chloride polymer to prepare a resin composition.
The resin composition is then subjected to calendering to form a
film comprising a flexible vinyl chloride resin, thereby obtaining
a backing film for use in the pressure-sensitive adhesive sheet
for skin adhesion according to the present invention.
[0029] According to the present invention, a polyester plasticizer
is used in place of the conventional epoxidized soybean oil. The
polyester plasticizer used in the present invention comprises, for
example, a polyester obtained by polycondensation of an aliphatic
or aromatic dicarboxylic acid having 2 to 10 carbon atoms, such
as adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic
acid, terephthalic acid, and a glycol having 2 to 10 carbon atoms,
such as ethylene glycol, propylene glycol, butylene glycol, neopentyl
glycol. In particular, according to the present invention, the polyester
plasticizer having a number average molecular weight of about 1,500
to about 3,000 is used in an amount of about 40 to about 70 parts
by weight, preferably about 45 to about 65 parts by weight, per
100 parts by weight of the vinyl chloride polymer.
[0030] If the number average molecular weight of the polyester
plasticizer is less than about 1,500, the plasticizer migrates from
the backing film it is compound in to the pressure-sensitive adhesive
layer, and this results in a decrease in adhesive force of the pressure-sensitive
adhesive with the passage of time. On the other hand, if the number
average molecular weight of the polyester plasticizer is more than
about 3,000, such a polyester plasticizer has poor compatibility
with the vinyl chloride polymer, making it difficult to produce
the backing film by calendering, and also the plasticizer bleeds
out in the backing film obtained, decreasing the adhesive force
of the pressure-sensitive adhesive to the backing film.
[0031] Particularly, the amount of the polyester plasticizer compounded
is generally about 40 to about 70 parts by weight per 100 parts
by weight of the vinyl chloride polymer such that the backing film
for the pressure-sensitive adhesive sheet for skin adhesion has
an appropriate modulus of elasticity that is flexible and adaptable
to a skin.
[0032] In the vinyl chloride resin film as the backing film for
use in the pressure-sensitive adhesive sheet for skin adhesion,
a metallic soap has conventionally been used as a stabilizer. However,
use of the metallic soap alone provides insufficient heat stability
of the resin composition in producing a film by calendering, causing
discoloration or decomposition of the resin composition. Even if
the metallic soap is compounded in larger amounts in order to overcome
this disadvantage, blooming or bleeding occurs, resulting in lowering
the adhesive force of the pressure-sensitive adhesive to the backing
film.
[0033] In view of the above, according to the present invention,
a combination of at least one metallic soap selected from the group
consisting of fatty acid calcium, fatty acid zinc and fatty acid
barium, and hydrotalcite is used as the stabilizer. Of those metallic
soaps is preferably used particularly a combination of fatty acid
calcium and fatty acid zinc, which exhibits a high stabilization
effect due to the synergistic effect when used as a combination
(hereinafter referred to as a "Ca--Zn type stabilizers").
[0034] The fatty acid component of the metallic soap includes generally
saturated or unsaturated fatty acids having 12 to 20 carbon atoms,
such as lauric acid, stearic acid, ricinolic acid, etc.
[0035] Examples of the metallic soap preferably include calcium
laurate, calcium stearate, calcium ricinolate, zinc laurate, zinc
ricinolate, zinc stearate, barium laurate, barium stearate, barium
ricinolate.
[0036] Hydrotalcite has the functions of not only imparting a heat
stability required in the resin composition in the calendering,
but also imparting a resistance to oxidation or decomposition to
the film during use or storage, so that a life of the film can be
prolonged. However, if hydrotalcite is used alone as the stabilizer,
the heat stability of the resin composition in calendering the resin
composition greatly deteriorates, regardless of the compounding
amount thereof, resulting in discoloration or decomposition of the
resin. As a result, the resin composition cannot be formed into
a film.
[0037] Hydrotalcite is generally a non-stoichiometric, basic aluminum
magnesium carbonate represented by the following compositional formula
Mg.sub.1-xAl.sub.x(OH).sub.2(CO.sub.3).sub.x/2.mH.sub.2O
[0038] wherein x is generally within the range of 0<x.ltoreq.0.33,
and m is generally within the range of 0.ltoreq.m.ltoreq.0.5, and
is a commercially available product (Sekkai and Sekko (Lime and
Gypsum), vol. 187, pages 47-53 (1983)).
[0039] The amount of at least one metallic soap selected from the
group consisting of fatty acid calcium, fatty acid zinc and fatty
acid barium, used as the stabilizer in the present invention is
not particularly limited, and an appropriate amount thereof is used.
However, the amount of at least one metallic soap compounded is
preferably within the range of about 0.5 and about 2.5 parts by
weight per 100 parts by weight of the vinyl chloride polymer. If
the amount of the metallic soap compounded is less than about 0.5
part by weight per 100 parts by weight of the vinyl chloride polymer,
even if the metallic soap is used in combination with hydrotalcite
as the stabilizer, the resin composition may lack its heat stability
in calendering. On the other hand, if the amount of the metallic
soap compounded is more than about 2.5 parts by weight per 100 parts
by weight of the vinyl chloride polymer, blooming or bleeding may
be caused, resulting in decrease of the adhesive force of the pressure-sensitive
adhesive to the backing film.
[0040] Hydrotalcite used in combination with the metallic soap
as the stabilizer in the present invention is used in an amount
of about 0.1 to about 1.0 part by weight per 100 parts by weight
of the vinyl chloride polymer. If the amount of hydrotalcite compounded
is less than about 0.1 part by weight per 100 parts by weight of
the vinyl chloride polymer, the resin composition lacks its heat
stability in calendering, and discoloration of the resin composition
is caused. On the other hand, if the amount of hydrotalcite compounded
is more than about 1.0 part by weight per 100 parts by weight of
the vinyl chloride polymer, coloration undesirably occurs due to
hydrotalcite.
[0041] Thus, according to the present invention, a film comprising
a vinyl chloride composition having compounded therewith the polyester
plasticizer as the plasticizer and a mixture of the metallic soap
and hydrotalcite as the stabilizer is used as the backing film for
the pressure-sensitive adhesive sheet for skin adhesion. Such a
backing film has an advantage from the standpoint of production
in that it has excellent heat stability during forming a film from
the resin composition by calendering, and undesirable coloration
or the like does not occur. Further, the pressure-sensitive adhesive
sheet for skin adhesion comprising the backing film thus obtained
and the pressure-sensitive adhesive layer for skin adhesion provided
thereon is advantageous in that since the plasticizer does not migrate
into the pressure-sensitive adhesive layer, the adhesive force of
the pressure-sensitive adhesive does not greatly decrease even with
the lapse of long term, and the initial adhesive force is substantially
maintained.
[0042] According to the present invention, the backing film for
the pressure-sensitive adhesive sheet for skin adhesion may contain
conventional stabilizers together with the above-described stabilizers,
if desired, so long as the conventional stabilizers do not migrate
from the backing film into the pressure-sensitive adhesive layer
or if migrated they do not decrease the adhesive force of the pressure-sensitive
adhesive. Examples of such conventional stabilizers include organic
phosphite-based stabilizers. Further, according to the present invention,
the backing film for the pressure-sensitive adhesive sheet for skin
adhesion may contain various additives conventionally compounded
with the vinyl chloride resin, for example, coloring materials,
light stabilizers, antioxidants, ultraviolet absorbents, modifiers,
fillers, flame retardants, antistatic agents, mildew-proofing agents
and lubricants, if desired.
[0043] The backing film for the pressure-sensitive adhesive sheet
for skin adhesion according to the present invention preferably
has a thickness within the range of about 40 to about 100 .mu.m
such that when the pressure-sensitive adhesive sheet for skin adhesion
is adhered to the skin, the backing film is well adaptable to the
skin and well follows the skin, so that the user has no uncomfortable
feeling.
[0044] According to the preferred embodiment of the present invention,
the backing film for the pressure-sensitive adhesive sheet for skin
adhesion can be obtained such that the resin composition comprising
the vinyl chloride polymer having compounded therewith the polyester
plasticizer having a number average molecular weight of about 1,500
to about 3,000, the stabilizer comprising at least one metallic
soap selected from the group consisting of fatty acid calcium, fatty
acid zinc and fatty acid barium, hydrotalcite, and if necessary,
the above-described additives is molded into a film by calendering.
Since the resin composition contains the polyester plasticizer as
the plasticizer and also a mixture of the metallic soap and hydrotalcite
as the stabilizer, the resin composition has excellent heat stability
during calendering, and as a result, undesirable coloration or the
like does not occur.
[0045] The pressure-sensitive adhesive sheet for skin adhesion
according to the present invention can be obtained by providing
the pressure-sensitive adhesive layer for skin adhesion on one side
of the above-described backing film.
[0046] The pressure-sensitive adhesive which can be used in the
present invention includes conventional acrylic pressure-sensitive
adhesives and natural rubber pressure-sensitive adhesives, and there
can be also used without any particular limitation any optional
pressure-sensitive adhesives that have less skin irritation and
can be used as medical pressure-sensitive adhesives, such as synthetic
rubber pressure-sensitive adhesives, silicone pressure-sensitive
adhesives and vinyl ether pressure-sensitive adhesives.
[0047] Of various pressure-sensitive adhesives, acrylic pressure-sensitive
adhesives are preferably used in the present invention from the
standpoint of a dermal pathology that it causes less allergy to
skin.
[0048] Of the acrylic pressure-sensitive adhesives, acrylic pressure-sensitive
adhesives comprising an acrylic copolymer are preferably used. The
acrylic copolymer is obtained by copolymerizing an alkyl acrylate
having 4 to 12 carbon atoms in the alkyl moiety which gives a polymer
having a low glass transition temperature, such as 2-ethylhexyl
acrylate or isononyl acrylate, as the main comonomer component,
and optionally a vinyl ester, such as an alkyl (meth)acrylate having
1 to 3 carbon atoms in the alkyl moiety (e.g., methyl (meth)acrylate,
ethyl (meth)acrylate or the like), vinyl acetate or N-methyl-2-pyrrolidone,
as a component which gives a cohesive force, or a polar monomer
having a polar group such as a hydroxyl group and/or a carboxyl
group, such as (meth) acrylic acid or hydroxyalkyl (meth) acrylate
having an alkyl group containing 2 to 10 carbon atoms in the hydroxyl
moiety (e.g., hydroxyethyl ester, hydroxypropyl ester or the like),
as a component which gives a cohesive force and also a crosslinking
site. Use of polar monomers having a hydroxyl group and/or a carboxyl
group or the like polar groups is preferred since the resultant
acrylic pressure-sensitive adhesive contains a hydroxyl group and/or
a carboxyl group or the like polar groups so that it has excellent
adhesive force to the backing film. Those comonomers are copolymerized
in an appropriate organic solvent such as aliphatic hydrocarbon,
alicyclic hydrocarbon, aromatic hydrocarbon, or aliphatic carboxylic
acid ester, more specifically in ethyl acetate or toluene to produce
an organic solvent type acrylic pressure-sensitive adhesive.
[0049] However, the pressure-sensitive adhesive for skin adhesion
according to the present invention is not limited to the above-described
organic solvent type pressure-sensitive adhesive, and is used in
any form such as an emulsion type or a hot melt type. Those pressure-sensitive
adhesives may be used alone or as mixtures of two or more thereof.
The pressure-sensitive adhesive layer has a thickness of generally
about 20 to about 80 .mu.m, and preferably about 30 to about 60
.mu.m, from the viewpoint of sufficient adhesion to the skin.
[0050] If desired, a crosslinking agent may be compounded with
the pressure-sensitive adhesive. Examples of the crosslinking agent
include modified polyisocyanates such as tolylenediisocyanate trimethylol
propane adduct and tris (2,3-epoxypropyl) isocyanurate, and organometallic
compounds called chelater, such as aluminum tris(ethyl acetoacetate).
A small amount, e.g., 0.05 to 1% by weight based on the weight of
the composition, of the crosslinking agent is compounded with the
pressure-sensitive adhesive, and such a pressure-sensitive adhesive
is coated on one side of the backing film and dried, and then, if
desired, heated to crosslink the acrylic pressure-sensitive adhesive,
thereby the adhesive force of the pressure-sensitive adhesive can
be controlled.
[0051] According to the present invention, prior to forming the
pressure-sensitive adhesive layer for skin adhesion on one side
of the backing film, the surface of the backing film, to which the
pressure-sensitive adhesive is applied, maybe subjected to a corona
discharge treatment or coated with the conventional various primers,
thereby increasing wettability or anchoring effect between the backing
film and the pressure-sensitive adhesive.
[0052] The pressure-sensitive adhesive layer is formed on one side
of the backing film by directly coating a solution of the pressure-sensitive
adhesive on the backing film and drying, or by melting a hot-melt
pressure-sensitive adhesive and then directly coating the same on
the backing film by an extruder. However, in order to prevent unnecessary
elongation or curl of the backing film, it is preferable to use
a so-called transfer method comprising previously forming the pressure-sensitive
adhesive layer on one side of a release sheet by an appropriate
method, laminating the backing film on this pressure-sensitive adhesive
layer, and transferring the pressure-sensitive adhesive layer onto
the backing film.
[0053] The pressure-sensitive adhesive sheet for skin adhesion
according to the present invention can be used as a dressing, a
bandage or the like, and also can be made as a first-aid adhesive
plaster by providing an absorbent pad for protecting a wound portion,
such as a cloth (e.g., gauze) or a sponge pad, at a central region
on the surface of the pressure-sensitive adhesive layer.
EXAMPLES
[0054] The present invention is explained in more detail by referring
to the following examples, but the invention is not limited thereto.
In the examples and comparative examples, the Ca--Zn type stabilizer
used is M series manufactured by Dainippon Ink & Chemicals Inc.,
and the polyester stabilizer used is POLYCIZER W, a product of Dainippon
Ink & Chemicals Inc.
Example 1
[0055] Ca--Zn type stabilizer, hydrotalcite (ALKAMIZER I, a product
of Kyowa Kagaku Kogyo K.K.; in the formula described before, x=0.33,
m=0.50) and a polyester plasticizer having various number average
molecular weight (POLYCIZER W, a product of Dainippon Ink &
Chemicals Inc.) were blended with polyvinyl chloride (average degree
of polymerization: 1,300) as shown in Table 1 below, and the resulting
blend was sufficiently mixed with a Henschel mixer, and then kneaded
with a closed kneader. The resulting mixture was passed through
a strainer, and using a reverse L type four-roll calendering apparatus
(roll surface temperature: 180.degree. C.), a backing film for a
pressure-sensitive adhesive sheet having a thickness of 70 .mu.m
comprising a vinyl chloride resin was obtained.
[0056] Separately, 0.02 part by weight (solids content) of a modified
polyisocyanate (CORONATE L, a product of Nippon Polyurethane Kogyo
K.K.) was compounded with 100 parts by weight of a commercially
available acrylic pressure-sensitive adhesive (AR-2045, a product
of Rikidyne K.K.) to prepare a pressure-sensitive adhesive. This
pressure-sensitive adhesive was coated on the above-described backing
film in a dry thickness of 35 .mu.m.
[0057] A sample of a pressure-sensitive adhesive sheet for skin
adhesion comprising a backing film having provided on one side thereof
a pressure-sensitive adhesive layer was allowed to stand at room
temperature (23.degree. C.), or allowed to stand at 70.degree. C.
for 15 days to conduct accelerated deterioration. The sample thus
treated was adhered to a stainless steel plate in a width of 19
mm, and an adhesive force of the sample before measurement and after
allowing to stand at 23.degree. C. for 24 hours was measured at
a peel angle of 180.degree. and a tensile speed of 300 mm/min using
a constant speed extension tensile tester according to JIS Z 0237.
The adhesive force with the lapse of time of the sample was evaluated
by retention of a peel force after accelerated deterioration to
an ordinary peel force. The results obtained are shown in Table
1 below.
Examples 2 and 3
[0058] A backing film was obtained in the same manner as in Example
1 except that a resin composition as shown in Table 1 was prepared.
The pressure-sensitive adhesive as used in Example 1 was coated
on the backing film obtained to prepare a sample of a pressure-sensitive
adhesive sheet for skin adhesion. The ordinary peel force and the
retention of a peel force after accelerated deterioration were determined
on the sample in the same manner as in Example 1. The results obtained
are shown in Table 1 below.
Example 4
[0059] A backing film was obtained in the same manner as in Example
1 except that the compounding amount of hydrotalcite was changed
as shown in Table 1. The pressure-sensitive adhesive as used in
Example 1 was coated on the backing film obtained to prepare a sample
of a pressure-sensitive adhesive sheet for skin adhesion. The ordinary
peel force and the retention of a peel force after accelerated deterioration
were determined on the sample in the same manner as in Example 1.
The results obtained are shown in Table 1 below.
Comparative Example 1
[0060] A backing film was obtained in the same manner as in Example
1 except that a resin composition was prepared using a polyester
plasticizer having a number average molecular weight of 1,000 (POLYCIZER
W-1000, a product of Dainippon Ink & Chemicals Inc.) as shown
in Table 1. The pressure-sensitive adhesive as used in Example 1
was coated on the backing film obtained to prepare a sample of a
pressure-sensitive adhesive sheet for skin adhesion. The ordinary
peel force and the retention of a peel force after accelerated deterioration
were determined on the sample in the same manner as in Example 1.
The results obtained are shown in Table 1 below.
Comparative Example 2
[0061] A backing film was obtained in the same manner as in Example
1 except that a resin composition was prepared using dioctyl phthalate
as a plasticizer in place of the polyester plasticizer as shown
in Table 1. The pressure-sensitive adhesive as used in Example 1
was coated on the backing film obtained to prepare a sample of a
pressure-sensitive adhesive sheet for skin adhesion. The ordinary
peel force and the retention of a peel force after accelerated deterioration
were determined on the sample in the same manner as in Example 1.
The results obtained are shown in Table 1 below.
Comparative Example 3
[0062] A backing film was obtained in the same manner as in Example
1 except that a resin composition was prepared by compounding only
Ca--Zn type stabilizer as a stabilizer, and not using hydrotalcite
as shown in Table 1. The pressure-sensitive adhesive as used in
Example 1 was coated on the backing film obtained to prepare a sample
of a pressure-sensitive adhesive sheet for skin adhesion. The ordinary
peel force and the retention of a peel force after accelerated deterioration
were determined on the sample in the same manner as in Example 1.
The results obtained are shown in Table 1 below.
Comparative Example 4
[0063] A backing film was obtained in the same manner as in Example
1 except that a resin composition was prepared using a polyester
plasticizer having a number average molecular weight of 2,300 (POLYCIZER
W-2310, a product of Dainippon Ink & Chemicals Inc.) as a plasticizer
and also using a combination of Ca--Zn type stabilizer and epoxidized
soybean oil (W-100EL, a product of Dainippon Ink & Chemicals
Inc.) as a stabilizer as shown in Table 1. The pressure-sensitive
adhesive as used in Example 1 was coated on the backing film obtained
to prepare a sample of a pressure-sensitive adhesive sheet for skin
adhesion. The ordinary peel force and the retention of a peel force
after accelerated deterioration were determined on the sample in
the same manner as in Example 1. The results obtained are shown
in Table 1 below.
1 TABLE 1 Example 1 Example 2 Example 3 Example 4 C. Example 1
C. Example 2 C. Example 3 C. Example 4 Formulation of resin composition
(parts by weight) Polyvinyl chloride 100 100 100 100 100 100 100
100 Ca--Zn type stabilizer 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Hydrotalcite
0.3 0.3 0.3 0.2 0.3 0.3 Epoxidized soybean oil.sup.1) 3.0 Polyester
plasticizer.sup.2) W-1000 (M.W.: 1,000) 40 W-1600 (M.W.: 1,600)
44 W-2050 (M.W.: 2,000) 48 W-2310 (M.W.: 2,300) 50 50 50 47 Dioctyl
phthalate 40 Adhesive force with the lapse of time Ordinary peel
force (gf/19 mm 930 910 900 910 820 810 800 820 width) Retention
of peel force after 88 87 81 85 60 40 65 41 accelerated deterioration
(%) Notes: .sup.1)W-100EL, a product of Dainippon Ink & Chemicals
Inc. .sup.2)POLYCIZER W, a product of Dainippon Ink & Chemicals
Inc. M.W.: Molecular weight C. Example: Comparative Example
Reference Example 1
[0064] 100 Parts by weight of 2-ethylhexyl acrylate, 40 parts by
weight of vinyl acetate and 5 parts by weight of acrylic acid were
copolymerized in ethyl acetate to obtain a solution of an acrylic
pressure-sensitive adhesive A having a solids content concentration
of 35 wt %.
Reference Example 2
[0065] 65 Parts by weight of isononyl acrylate and 35 parts by
weight of vinyl acetate were copolymerized in ethyl acetate to obtain
a solution of an acrylic pressure-sensitive adhesive B having a
solids content concentration of 35 wt %.
Reference Example 3
[0066] 100 Parts by weight of natural rubber, 100 parts by weight
of styrene-butadiene copolymer, 170 parts by weight of terpene resin,
100 parts by weight of low number average molecular weight polyisoprene
(number average molecular weight: 30,000) and 3 parts by weight
of bisphenol as a stabilizer were uniformly mixed in toluene to
obtain a solution of a rubber pressure-sensitive adhesive C having
a solids content concentration of 25 wt %.
Example 5
[0067] 1.0 Part by weight of Ca--Zn type stabilizer, 0.7 part by
weight of hydrotalcite (ALKAMIZER I, a product of Kyowa Kagaku Kogyo
K.K.) and a polyester plasticizer having a number average molecular
weight of 2,300 (POLYCIZER W-2310, a product of Dainippon Ink &
Chemicals Inc.) were compounded with 100 parts by weight of polyvinyl
chloride (average degree of polymerization: 1,300), and the resulting
blend was sufficiently mixed with a Henschel mixer, and then kneaded
with a closed kneader. The resulting mixture was passed through
a strainer, and using a reverse L type four-roll calendering apparatus
(roll surface temperature: 180.degree. C.), a backing film for a
pressure-sensitive adhesive sheet having a thickness of 70 .mu.m
comprising a vinyl chloride resin was obtained.
[0068] Separately, the solution of a pressure-sensitive adhesive
A prepared in Reference Example 1 above was coated on a release
sheet, one surface of which having been subjected to release treatment
with a silicone resin, in a dry thickness of about 40 .mu.m, and
dried to form a pressure-sensitive adhesive layer. The backing film
obtained above was laminated on this pressure-sensitive adhesive
layer, and the pressure-sensitive adhesive layer was transferred
to the backing film, thereby obtaining a pressure-sensitive adhesive
sheet for skin adhesion.
[0069] A sample having a width of 19 mm and a length of 150 mm
was prepared from the pressure-sensitive adhesive sheet for skin
adhesion thus obtained. The sample was adhered to a phenolic resin
plate, and an initial value of an adhesive force of the pressure-sensitive
adhesive sheet and an adhesive force of the pressure-sensitive adhesive
sheet after allowing to stand the same in a constant temperature
bath at 50.degree. C. or 70.degree. C. for 30 days were measured.
The adhesive force was measured by conducting a 180.degree. peeling
test at a tensile speed of 300 mm/min using a constant speed extension
tensile tester under the conditions of temperature of 23.+-.2.degree.
C. and a relative humidity of 65.+-.15% according to JIS Z 0237.
The results obtained are shown in Table 2.
Examples 6 and 7
[0070] A layer comprising each of the pressure-sensitive adhesives
B and C prepared in Reference Examples 2 and 3 was formed on the
backing film prepared in Example 5 in a thickness of about 40 .mu.m
to obtain the respective pressure-sensitive adhesive sheet for skin
adhesion. The adhesive force of those pressure-sensitive adhesive
sheets for skin adhesion was measured in the same manner as in Example
5. The results obtained are shown in Table 2 below.
Comparative Example 5
[0071] A pressure-sensitive adhesive layer was formed on the backing
film prepared in Comparative Example 4 in the same manner as in
Example 5 to obtain a pressure-sensitive adhesive sheet for skin
adhesion. The adhesive force of the pressure-sensitive adhesive
sheet for skin adhesion was measured in the same manner as in Example
5. The results obtained are shown in Table 2 below.
2 TABLE 2 Example Example Example Comparative 5 6 7 Example 5 Pressure-sensitive
A B C A adhesive Adhesive force (gf/19 mm width) Initial value 850
720 730 810 50.degree. C. .times. 30 days 780 680 700 410 70.degree.
C. .times. 30 days 720 650 680 250
Example 8
[0072] The pressure-sensitive adhesive sheet for skin adhesion
prepared in Example 5 was allowed to stand at 50.degree. C. for
30 days, and then cut into a sample having a width of 19 mm and
a length of 72 mm. This sample was adhered on the second joint of
the fingers of ten subjects for 8 hours. After conducting an ordinary
kitchen work, the adhesion property of the sheet to the skin and
the adhesive remaining on the skin when peeling the adhesive sheet
from the fingers were examined.
[0073] The evaluation standard was conducted using the five grades
of 5: Good, 3: Moderate, and 1: Poor. As a result, the evaluation
of the adhesive property to the skin was 5, and the evaluation of
the adhesive remaining was 4.
Comparative Example 6
[0074] The pressure-sensitive adhesive sheet for skin adhesion
prepared in Comparative Example 5 was allowed to stand at 50.degree.
C. for 30 days, and cut into a test piece having a width of 19 mm
and a length of 72 mm. The adhesion property of the sheet to the
skin and the adhesive remaining on the skin when peeling the adhesive
sheet from the fingers were examined in the same manner as in Example
8. The evaluation of the adhesive property to the skin was 2 (the
adhesive sheet peeled during adhering in three test persons), and
the evaluation of the adhesive remaining was 5.
Example 9
[0075] Ca--Zn type stabilizer, hydrotalcite (ALKAMIZER I, a product
of Kyowa Kagaku Kogyou K.K.), and a polyester plasticizer having
a number average molecular weight of 2,300 (POLYCIZER W-2300, a
product of Dainippon Ink & Chemicals Inc.) were compounded with
a polyvinyl chloride (average degree of polymerization: 1,300) as
shown in Table 3, and the resulting blend was sufficiently mixed
with a Henschel mixer to prepare a resin composition. This resin
composition was subjected to heat resistance test of kneading the
composition for 15 minutes using rolls having a surface temperature
of 180.degree. C. to examine the degree of discoloration (.DELTA.E).
The results obtained are shown in Table 3 below. If the .DELTA.E
is smaller than 1.0, it can be judged that the resin composition
has the calendering property. Further, the calendering property
was examined on the resin composition using a plast mill (190.degree.
C..times.60 rpm). If decomposition time is 15 minutes or more, it
can be judged that the resin composition has the calendering property.
Comparative Examples 7 to 9
[0076] The resin compositions were prepared in the same manner
as in Example 9 except for preparing the resin compositions as shown
in Table 3, and the calendering property thereof was examined. The
results obtained are shown in Table 3 below. The resin compositions
of Comparative Examples 7 and 8 do not have the calendering property.
The resin composition of Comparative Example 9 can provide a film
by calendering, but since the obtained backing film contains an
epoxidized soybean oil in place of hydrotalcite, the pressure-sensitive
adhesive sheet for skin adhesion obtained by coating the pressure-sensitive
adhesive on the backing film is decreased in adhesive force with
the passage of time.
Example 10
[0077] First-aid adhesive plasters were prepared by attaching an
absorbent pad made of gauze (15 mm.times.36 mm) at a central region
on the surface of the pressure-sensitive adhesive layer of the pressure-sensitive
adhesive sheet for skin adhesion produced in Examples 1 to 9 cut
to a size of 19 mm.times.72 mm.
3 TABLE 3 Com- Com- Com- parative parative parative Example 9 Example
7 Example 8 Example 9 Resin composition formulation (parts by weight)
Polyvinyl chloride 100 100 100 100 Ca--Zn type stabilizer 1.0 1.0
1.0 Hydrotalcite 0.3 0.3 Epoxidized soybean oil.sup.1) 3.0 Polyester
plasticizer.sup.2) 50 50 50 47 Calendering property Discoloration
(.DELTA.E) 0.5 1.5 9.5 0.5 Decomposition time 17 11 4 17 (min) Notes:
.sup.1)W-100EL, a product of Dainippon Ink & Chemicals Inc.
.sup.2)POLYCIZER W-2310 (molecular weight: 2,300), a product of
Dainippon Ink & Chemicals Inc.
[0078] The present invention may be embodied in other specific
forms without departing from the spirit or essential characteristics
thereof. The present embodiment is therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by
the foregoing description and all changes which come within the
meaning and range of equivalency of the claims are therefore intended
to be embraced therein.
|