JP4914590B2 - Copolymer emulsion for adhesive for human body sticking, adhesive composition for human body sticking, and patch for human body sticking. - Google Patents

Description

  The present invention relates to a sticking material for sticking a human body such as a pressure-sensitive adhesive tape or sheet used in the field of medicine, home or sports, a pressure-sensitive adhesive composition used therefor, and a copolymer emulsion for obtaining this pressure-sensitive adhesive composition. .

  In the medical, home or sports fields, adhesive tapes or sheets (hereinafter collectively referred to as synthetic resin films or fiber fabrics) for the treatment of diseases such as wounds and sprains, the fixation of medical materials such as gauze and catheters, etc. "Adhesive tape" is used. Conventionally, organic solvent-based adhesives have been frequently used for adhesive tapes. However, from the viewpoint of environmental problems in recent years, safety, and resource saving, the shift from organic solvent-based pressure-sensitive adhesive compositions to water-based pressure-sensitive adhesives has become a trend. However, water-based adhesives are inferior in water resistance compared to organic solvent-based adhesives. Therefore, the pressure-sensitive adhesive tape obtained using the water-based pressure-sensitive adhesive may be peeled off unexpectedly during application due to the influence of sweat from the skin or exudate from a wound or catheter puncture site. In addition, the adhesiveness and cohesive force of the pressure-sensitive adhesive to the base material are reduced by moisture, and there is also a problem that an adhesive residue is generated on the skin when the pressure-sensitive adhesive tape is peeled off.

In Patent Document 1, 100 parts by weight of an emulsion polymer using a (meth) acrylic acid alkyl ester as a main raw material monomer and 5 to 50 weight percent of a solution polymer using a (meth) acrylic acid alkyl ester as a main raw material monomer An aqueous emulsion-type acrylic pressure-sensitive adhesive made of a mixture with a part, and a medical pressure-sensitive adhesive tape or sheet formed by forming a pressure-sensitive adhesive layer made of this pressure-sensitive adhesive on one side or both sides of a substrate have been proposed.
This pressure-sensitive adhesive is certainly better than organic solvent-based pressure-sensitive adhesives in terms of environmental issues, safety, etc., but since water-based pressure-sensitive adhesives and organic solvent-based pressure-sensitive adhesives must be used in combination, The manufacturing process becomes complicated. Moreover, the pressure-sensitive adhesive tape obtained using this pressure-sensitive adhesive cannot sufficiently solve the above-mentioned problems of peeling during use and adhesive residue.
In the industrial field, as a method for improving the water resistance of an aqueous pressure-sensitive adhesive composition, a method using a reactive emulsifier as an emulsifier, a method for reducing the particle diameter of an aqueous emulsion, and a specific monomer excellent in water resistance are introduced. Methods are known.
However, in addition to basic adhesive properties such as adhesive strength, cohesive strength, and tack, it is necessary for the adhesive for human body application to have no sense of incongruity to the skin. However, it is necessary to satisfy the required characteristics peculiar to medical products, such as not being peeled off unexpectedly by sweat or body fluids, and not having adhesive residue at the time of peeling.
Until now, there is no known one that sufficiently satisfies the required characteristics for such adhesives for human body application.

JP-A-9-249855 (page 2-3)

Therefore, the object of the present invention is to provide basic adhesive properties such as adhesive strength, cohesive strength, and tack suitable for human body sticking, less uncomfortable feeling during sticking, and resistance to sweat and body fluids even when stuck for a long time. Furthermore, another object of the present invention is to provide a patch for sticking a human body that does not leave a sticky layer (so-called “glue residue”) on the part to be applied at the time of peeling.
Another object of the present invention is to provide a pressure-sensitive adhesive composition for obtaining this patch for sticking a human body.
Still another object of the present invention is to provide a copolymer emulsion for obtaining this pressure-sensitive adhesive composition.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using a copolymer emulsion obtained by emulsion polymerization of a monomer mixture having a specific composition. Based on this, the present invention has been completed.

Thus, according to the present invention, emulsion copolymerization of a monomer mixture containing methyl acrylate, (meth) acrylic acid ester having 4 to 12 carbon atoms, and acrylic acid and / or methacrylic acid is carried out. There is provided a copolymer emulsion for pressure-sensitive adhesive for human body patch comprising the copolymer obtained as described above.
The copolymer emulsion for pressure-sensitive adhesive for human body sticking of the present invention comprises 5 to 35% by weight of methyl acrylate, 60 to 90% by weight of (meth) acrylate ester having an alkyl group having 4 to 12 carbon atoms, acrylic acid and It is preferable to contain a copolymer obtained by emulsion copolymerization of a monomer mixture containing 2 to 15% by weight of methacrylic acid.
Moreover, in the copolymer emulsion for adhesives for human body sticking of this invention, it is preferable that the quantity of acrylic acid and methacrylic acid is 2 to 15 weight% in total, and acrylic acid and methacrylic acid in a monomer mixture The weight ratio (acrylic acid / methacrylic acid) is more preferably in the range of 1/99 to 50/50.
In the copolymer emulsion for pressure-sensitive adhesive for human body sticking of the present invention, the average particle size of the copolymer particles in the emulsion is preferably in the range of 0.08 to 0.20 μm.

Moreover, according to this invention, the adhesive composition for human body sticking formed by containing the copolymer emulsion for adhesives for human body sticking of the said invention is provided.
In the pressure-sensitive adhesive composition for human body sticking of the present invention, it is preferable that the adhesive strength is in the range of 5 to 15 N / 25 mm and the submerged adhesive strength is in the range of 5 to 12 N / 25 mm.
Moreover, in the adhesive composition for human body sticking of this invention, it is preferable that the absolute value of a water immersion adhesive force change rate exists in the range of 0 to 60%.
Furthermore, according to the present invention, there is provided a patch for attaching a human body comprising a substrate and an adhesive layer formed on the surface of at least one of the adhesive layers using the adhesive composition for applying a human body of the present invention. The

  The adhesive material for sticking a human body of the present invention has good adhesion to each part of the body to be applied and followability to skin extension, and also has sufficient resistance to sweat and exudate generated from the applied part. Furthermore, at the time of peeling, the composition does not remain on the application site, and can be peeled while maintaining good adhesion to the substrate.

The copolymer emulsion for pressure-sensitive adhesive for human body sticking of the present invention is a single emulsion comprising methyl acrylate, (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms, and acrylic acid and / or methacrylic acid. It contains a copolymer obtained by emulsion copolymerization of a monomer mixture.
The monomer mixture for obtaining the copolymer emulsion for pressure-sensitive adhesive for human body sticking of the present invention contains methyl acrylate as an essential component. The content of methyl acrylate in the monomer mixture is preferably 5 to 35% by weight, more preferably 10 to 30% by weight.
By using methyl acrylate, the pressure-sensitive adhesive composition containing the resulting copolymer emulsion improves the adhesive strength during sweating, cohesive strength, adhesion to the substrate, and the like.
When the content of methyl acrylate is lower than the above lower limit, the water resistance of the pressure-sensitive adhesive composition containing the copolymer emulsion to be obtained, such as water adhesion strength and whitening resistance, decreases or the pressure-sensitive adhesive composition at the time of peeling. There is a risk that an object will remain on the application site, and if it is higher than the above upper limit, the tackiness of the pressure-sensitive adhesive composition may decrease or the pressure-sensitive adhesive composition may become hard, and the human body formed from this When the patch material is applied, the followability to the skin extension is lowered, and there is a possibility that a sense of incongruity is generated.

In the present invention, it is essential to use, in combination with methyl acrylate, a (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms as an emulsion copolymerizable monomer.
The amount of the (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms is preferably 60 to 90% by weight, more preferably 65 to 85% by weight based on the total monomers. preferable.
When the amount of the (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms is less than 60% by weight, the adhesive property between the pressure-sensitive adhesive composition containing the resulting copolymer emulsion and the substrate is increased. If it exceeds 90% by weight, the cohesive force may decrease.

Specific examples of the (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms include n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-amyl (meth) acrylate, (meth) Linear or branched alkyl groups such as isoamyl acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate (Meth) acrylic acid alkyl ester having the above.
The alkyl group of these (meth) acrylic acid esters may have a substituent such as a hydroxyl group or a halogen atom.
These monomers may be used individually by 1 type, and may use 2 or more types together.
Of these, butyl acrylate and 2-ethylhexyl acrylate are preferred, and 2-ethylhexyl acrylate is particularly preferred. When either of these two types of monomers is used, the resulting pressure-sensitive adhesive composition containing the copolymer emulsion exhibits good softness and followability to the skin near the skin surface temperature.

In the present invention, it is essential to use acrylic acid and / or methacrylic acid as the emulsion copolymerization monomer.
The total amount of acrylic acid and / or methacrylic acid used is preferably 2 to 15% by weight, more preferably 2 to 7% by weight, based on the monomer mixture. When the amount used is lower than 2% by weight, the polymerization stability of emulsion polymerization is lowered, and the resulting pressure-sensitive adhesive composition containing the copolymer emulsion may not exhibit sufficient adhesion to the skin. If the amount is more than 15% by weight, the pressure-sensitive adhesive becomes hard, and the followability to skin extension decreases when the pressure-sensitive adhesive tape is applied, which may cause a sense of discomfort.

  In the present invention, it is preferable to use acrylic acid and methacrylic acid in combination. When both are used in combination, the pressure-sensitive adhesive composition containing the resulting copolymer emulsion exhibits good adhesiveness with the skin, and when a patch is formed from this pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer Becomes difficult to flow out of the base material and skin. In order to obtain such characteristics, the weight ratio of acrylic acid and methacrylic acid used is preferably in the range of 1/99 to 50/50, and in the range of 10/90 to 40/60. More preferably.

In obtaining the copolymer emulsion for pressure-sensitive adhesive for human body sticking of the present invention, as a monomer, methyl acrylate, (meth) acrylic acid ester having 4 to 12 carbon atoms, and acrylic acid and methacrylic acid In addition, a monomer copolymerizable with these monomers can be used in combination.
As such a monomer, a methacrylic acid ester having an alkyl group having 1 carbon atom which may have a substituent; an alkyl group having 2 to 3 carbon atoms which may have a substituent ( (Meth) acrylic acid esters; α, β-ethylenically unsaturated carboxylic acids and derivatives thereof other than acrylic acid and methacrylic acid; α, β-ethylenically unsaturated carboxylic acid amides and derivatives thereof; crosslinkable monomers; Examples thereof include β-ethylenically unsaturated nitriles; carboxylic acid vinyl esters; aromatic vinyl compounds; conjugated dienes and the like.

Specific examples of these monomers include methyl methacrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) 2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, triethylene glycol (meth) acrylate; crotonic acid, itaconic acid, maleic acid, fumaric acid, methyl itaconate, butyl maleate Propyl fumarate; (meth) acrylamide, N-methylol (meth) acrylamide; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, triallyl isocyanurate; (meth) acrylonitrile; vinyl acetate; styrene; ; Rukoto can.
These monomers may be used alone or in combination of two or more.
The amount of these monomers used is not limited as long as the effects of the present invention are not impaired, but the monomer mixture is preferably 20% by weight or less, more preferably 10% by weight or less.

  In the present invention, (meth) acrylic acid ester is a general term for acrylic acid ester and methacrylic acid ester, and similarly, (meth) acrylic acid is a general term for acrylic acid and methacrylic acid.

The copolymer emulsion for adhesives for human body sticking of this invention can be obtained by carrying out the emulsion copolymerization of the said monomer mixture. There are no particular limitations on the type and amount of the polymerization auxiliary material used for the emulsion copolymerization and the polymerization conditions.
As the polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate and azo compounds such as azobisisobutyronitrile can be used. A redox polymerization catalyst may also be used. Specific examples of the redox polymerization catalyst include a combination of an organic peroxide such as t-butyl hydroperoxide, benzoyl peroxide and cumene hydroperoxide and a reducing agent such as Rongalite and sodium metabisulfite; potassium persulfate, A combination of ammonium persulfate and Rongalite, sodium thiosulfate and ascorbic acid can be used.

  As an emulsifier, anionic surfactants such as alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester, alkylbenzene sulfonate, alkyl ether disulfonate, fatty acid salt and naphthalene sulfonate formalin condensate; polyoxyethylene Nonionic surfactants such as alkyl ethers, polyoxyethylene alkylphenol ethers, sorbitan higher fatty acid esters, polyoxyethylene sorbitan higher fatty acid esters, polyoxyethylene higher fatty acid esters and glycerin higher fatty acid esters; It is done. In addition, a cationic surfactant may be used.

In the present invention, it is preferable to use a so-called copolymerizable emulsifier having a polymerizable unsaturated bond and a structure exhibiting surface activity in the molecule as the emulsifier. At this time, an anionic surfactant or the like may be used in combination.
Specific examples of the copolymerizable emulsifier include sodium alkylallylsulfosuccinate, sodium methacryloyloxypolyoxyalkylene sulfate, polyoxyethylene alkylallylphenol ether, polyoxyethylene alkylallylphenol ether sulfate, and the like. These reactive emulsifiers may be used in combination of two or more if necessary.
The amount of the copolymerizable emulsifier used is preferably in the range of 0.5 to 5% by weight based on the total amount of the monomer mixture. When the amount used is within this range, the copolymer emulsion is excellent in stability, and the water resistance of the pressure-sensitive adhesive composition comprising the resulting copolymer emulsion (water immersion adhesive force, water immersion adhesive force change rate and whitening resistance) Property).

  In the emulsion copolymerization, it is preferable to use a chain transfer agent. Although it does not specifically limit as a chain transfer agent, Mercaptan compounds, such as alkyl mercaptan, thioglycol, and 2-mercaptopropionic acid, can be illustrated. The amount used is not particularly limited, but is preferably 0.05 to 0.2% by weight based on the total monomers. When used within this range, the cohesive force of the pressure-sensitive adhesive composition containing the resulting copolymer emulsion at the time of application to the skin will be at a sufficient level, and the tack and adhesive strength will be excellent.

In the emulsion copolymerization, the method for adding the monomer is not particularly limited.
All monomers may be added all at once, or all monomers may be divided into two or more portions and polymerized sequentially. Furthermore, a method may be used in which a part of the monomer is added to the polymerization vessel in the initial stage of polymerization and the remaining is added sequentially. In addition, during the sequential addition, the monomer composition may be uniform or may be changed according to time.
After completion of the polymerization, post-treatment such as removal of residual monomers, pH adjustment, concentration and the like is performed as necessary. The method is not particularly limited.

  It is preferable that the copolymer emulsion for adhesives for human body sticking of this invention exists in the range whose average particle diameter of a copolymer is 0.08-0.20 micrometers. When the average particle size is in this range, the emulsion is excellent in stability and the water resistance of the pressure-sensitive adhesive composition containing the emulsion is excellent.

The pressure-sensitive adhesive composition for human body sticking of the present invention is a monomer mixture comprising methyl acrylate, (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms, and acrylic acid and / or methacrylic acid. It contains the copolymer emulsion for adhesives for human body sticking of this invention containing the copolymer obtained by emulsion copolymerization.
This pressure-sensitive adhesive composition is a thickener, a tackifier, a plasticizer, a drug, a colorant, a filler, and other additives as necessary. It can obtain by mix | blending.

The aqueous emulsion-type pressure-sensitive adhesive composition for human body sticking of the present invention preferably has the following characteristics based on the test method described later.
The adhesive force is preferably in the range of 5 to 15 N / 25 mm. When the adhesive strength is within this range, the adhesive is not peeled off when the skin is applied, and the adhesive can be removed from the skin without causing skin damage. In addition, adhesive force here shows the measured value by the test method of [adhesive strength] of the Example mentioned later.

  Moreover, it is preferable that a water immersion adhesive force exists in the range of 5-12N / 25mm. When the water immersion adhesive strength is within this range, the adhesive will not peel off even if you sweat or water is applied on the adhesive, and even if you try to remove the adhesive when the skin is dry, it will irritate the skin. There is no fear of giving. In addition, the immersion adhesive force here shows the measured value by the test method of [immersion adhesive force] of the Example mentioned later.

  Furthermore, it is preferable that the absolute value of the adhesive force change rate before and after immersion in a 0.9% NaCl aqueous solution (referred to as “water immersion adhesive force change rate”) is in the range of 0 to 60%. If it is such a range, even if an adhesive contacts with sweat or exudate, the favorable adhesiveness with respect to skin or a base material can be maintained. In addition, the submerged adhesive force change rate here shows the measured value by the test method of [submerged adhesive force change rate] of the Example mentioned later.

  Furthermore, the cohesive strength is preferably 300 minutes or more. When the cohesive force is less than 300 minutes, the adhesive layer tends to flow (extrude) from the base material or the skin, and the adhesive layer may remain on the skin when the patch is peeled off. The cohesive force here refers to a value measured by a test method for [cohesive force] in Examples described later.

  Furthermore, the pressure-sensitive adhesive composition of the present invention preferably has a tack of # 3 to # 26. When the tack is within this range, it can be easily applied to the skin, and the adhesive material does not cling to the hand, resulting in excellent operability. The tack here refers to a value measured by the [Tack] test method in the examples described later.

  Each characteristic of said adhesive composition can be suitably adjusted with the monomer composition of a copolymer, the average particle diameter of the copolymer particle in an emulsion, use of a copolymerizable emulsifier, etc.

The patch for human body sticking of this invention has a base material and the adhesion layer formed using the adhesive composition for human body sticking of this invention on the at least one surface.
The material of the substrate is not particularly limited as long as it is conventionally used in this field, and examples thereof include Japanese paper, crepe paper, nonwoven fabric, and plastic film. Among them, a polyolefin-based or polyester-based substrate that can be easily combined with other materials by adhesion or heat sealing is preferable.
In this invention, it is preferable that a base material is rich in a stretching property and a softness | flexibility, and has air permeability and moisture permeability.

Polyolefin base materials include polyethylene, polypropylene, ethylene / vinyl acetate copolymer (EVA), ethylene / ethyl acrylate copolymer (EEA), ethylene / methyl acrylate copolymer (EMA), and ethylene / methyl methacrylate. Examples thereof include a copolymer (EMMA), an ethylene / methacrylic acid polymer (EMAA), an ethylene / acrylic acid copolymer (EAA), and a mixture thereof.
Examples of the polyester base material include polyethylene terephthalate and polybutylene terephthalate.

  Emulsion-type pressure-sensitive adhesive composition has good adhesion to hydrophilic substrates such as rayon and cotton, but has poor adhesion to hydrophobic substrates such as polyolefins and polyesters. It is said that it is not good. However, the adhesive composition of the present invention has improved adhesion to these substrates by using methyl acrylate or the like as an essential constituent monomer of the copolymer emulsion.

By forming an adhesive layer made of the adhesive composition of the present invention on at least one surface of the substrate, the patch of the present invention can be obtained. The method for forming the adhesive layer is not particularly limited.
Although the form of a sticking material is not specifically limited, The form of an adhesive tape or a sheet can be illustrated.

Hereinafter, the present invention will be described by way of examples. In addition, the part and% in each example are mass references | standards unless there is particular notice.
Moreover, the evaluation method of each characteristic is as follows.

[Create specimen]
The pressure-sensitive adhesive composition is applied to a polyester film (trade name “Lumirror”, manufactured by Toray Industries, Inc.) of 25 μm so that the thickness after drying is 25 μm, and dried in an oven to prepare a sample of a pressure-sensitive adhesive sheet.

[Adhesive force]
Conforms to the “adhesive strength” test specified in JIS Z0237. A bakelite plate (thickness 20 mm × width 40 mm × length 150 mm, manufactured by Nimura Chemical Co., Ltd.) is prepared as an adherend, and the surface is wiped with a cloth soaked with ethyl acetate. A test piece cut out to a width of 25 mm × a length of about 200 mm was bonded to the adherend, and a spring hardness of 80 ± 5 HS defined by JIS K6253, a width of about 45 mm and a diameter of about 95 mm covered with a rubber layer of about 6 mm, Using a crimping apparatus having a mass of about 2,000 g, the test piece is reciprocated once at a speed of 300 mm / min for crimping. After being left in an environment of 23 ° C. and 65% RH for 20 minutes, the specimen is folded back in the 180 ° direction and peeled off at a speed of 300 mm / min using a material tester defined in JIS B7721. Repeat the test three times and average the measurements.
This adhesive strength should be in the range of 5-15 N / 25 mm.

[Immersion adhesive strength]
The test piece is immersed in a 0.9% NaCl aqueous solution adjusted to 37 ° C. with the adhesive surface exposed. After immersing the test piece for 3 hours while maintaining the temperature of this aqueous solution at 37 ° C., the test piece was taken out and pasted on the adherend prepared in the same manner as the adherend of the [Adhesive strength] test in the same manner. Match. After being left in an environment of 23 ° C. and 65% RH for 20 minutes, the specimen is folded back in the 180 ° direction and peeled off at a speed of 300 mm / min using a material tester defined in JIS B7721. Repeat the measurement three times to obtain the average value.
This immersion adhesive strength is preferably in the range of 5 to 12 N / 25 mm.

[Remaining ratio of submerged adhesive layer]
Moreover, in the said water immersion adhesion test, the grade of peeling of the adhesion layer from a test piece when a test piece is peeled off from a to-be-adhered body is shown by the ratio of the peeling area with respect to all the test piece areas. A lower ratio is better.

[Whitening resistance]
In the water immersion adhesion test, the whitening state immediately after the immersion test piece is taken out is observed and judged according to the following criteria. A lower degree of whitening is preferred.
○: No whitening at all.
Δ: The test piece is slightly whitened on the entire surface.
X: The test piece is entirely whitened.

[Change rate of water adhesion]
Moreover, the change rate of the adhesive force before and behind immersion in 0.9% NaCl aqueous solution is calculated by the following formula.
Submerged adhesive strength change rate (%) = [(Adhesive strength−Submerged adhesive strength) / (Adhesive strength)] × 100
It is better that the absolute value of the change rate of the submerged adhesive force is small.

[Cohesive strength]
Conforms to the “holding power” test specified in JIS Z0237. A test piece cut out to a width of 25 mm × a length of about 60 mm is pasted on a cleaned SUS304 steel plate so that an area of 25 mm × 25 mm is in contact therewith. The adherend is installed in a creep tester equipped with a thermostatic bath set to an internal temperature of 40 ° C. (manufactured by Shinko Scientific Co., Ltd.), and a 1 kg weight is suspended from the end of the test piece protruding from the adherend. The time until the test piece falls from the adherend is measured.
The cohesive force should have a larger value.

[tack]
Conforms to the “Inclined Ball Tack” test specified in JIS Z0237. The tilt angle is set to 30 ° C., the high carbon chromium bearing steel specified in JIS G4805 is rolled on the test piece, and the number of the stopped ball is recorded according to the ball reading specified in JIS B1501.
The tack indicates that the larger the ball number, the larger the tack.

[Skin application evaluation]
(Peeling area ratio)
Polyester nonwoven basis weight 44 g / m ² of adhesive composition was applied to (DuPont's trade name "Sontara # 8010"), and dried in an oven, the adhesive sheet dry coating amount of 50 g / m ² of the adhesive layer Create A test piece of 25 mm × 75 mm is cut out from this adhesive sheet and attached to the back of eight subjects. The area of the part peeled off from the skin after 8 hours is measured, the ratio to the total area of the test piece is calculated, and the average value of this ratio for 8 subjects is defined as the peeled area ratio (%).
The smaller the peel area ratio, the better.
(Uncomfortable feeling during application)
In addition, the subject is asked whether he / she felt uncomfortable during sticking, and the number of subjects who felt uncomfortable is recorded.

[Example 1]
82 parts of 2-ethylhexyl acrylate, 10 parts of methyl acrylate, 4 parts of methyl methacrylate, 1 part of acrylic acid, 3 parts of methacrylic acid, 0.1 part of octyl thioglycolate with respect to 100 parts of these monomers, reaction A neutral ammonia-type anionic surfactant (trade name “AQUALON KH-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) dissolved in 32 parts of ion-exchanged water was added and stirred to emulsify the emulsion. Was placed in a dropping funnel.
A four-necked flask equipped with a stirrer, a condenser, a thermometer and the above dropping funnel was charged with 75 parts of ion-exchanged water and an anionic emulsifier polyoxyethylene alkyl ether sulfate (trade name “RA-9607, manufactured by Nippon Emulsifier Co., Ltd.”). )) 0.2 parts were charged, the inside of the flask was replaced with nitrogen gas, the internal temperature was raised to 80 ° C. while stirring, and a 3% aqueous solution containing 0.1 part of potassium persulfate was added.
After 5 minutes, the dropping of the emulsion was started from the dropping funnel, and a 3% aqueous solution containing 0.35 part of potassium persulfate was dropped from another dropping port over 3 hours.
While maintaining the internal temperature at 80 ° C., 60 parts after the completion of the emulsion dropping, 2 parts of 1% t-butyl hydroperoxide aqueous solution and 2 parts of 1% Rongalite aqueous solution were added in three portions every 30 minutes.
The mixture was further aged at 80 ° C. for 60 minutes while continuing to stir, and then cooled and neutralized with aqueous ammonia to obtain an acrylic copolymer emulsion (copolymer emulsion for pressure sensitive adhesive for human body sticking) having a solid content of 45%. . The average particle size measured with a particle size measuring device (trade name “Microtrac” manufactured by Nikkiso Co., Ltd.) was 0.1 μm.

An antifoaming agent and a leveling agent are added to the obtained acrylic copolymer emulsion (copolymer emulsion for pressure-sensitive adhesive for human body sticking), pH is adjusted to 8.0 with aqueous ammonia, and a viscosity modifier is further added. To 18,000 mPa · s (BL viscometer, # 4 rotor used, 12 rpm) to obtain a pressure-sensitive adhesive composition for human body sticking.
This pressure-sensitive adhesive composition for human body application was applied to a polyester film (trade name “Lumirror” manufactured by Toray Industries, Inc.) of 25 μm so that the thickness after drying was 25 μm, dried in an oven, and then pressure-sensitive adhesive sheet (human body application) Adhesive patch) was obtained.
Each characteristic was evaluated about this adhesive sheet. The results are shown in Table 1.

[Examples 2-3 and Comparative Examples 1-2]
A copolymer emulsion for a human body sticking adhesive and a human body sticking pressure sensitive adhesive composition were obtained in the same manner as in Example 1 except that the monomer composition was changed as shown in Table 1. The results are shown in Table 1.
Using the pressure-sensitive adhesive composition for human body sticking shown in Table 1, an adhesive sheet (a patch for human body sticking) was obtained in the same manner as in Example 1.
About this adhesive sheet, each characteristic was evaluated similarly to Example 1. The results are shown in Table 1.

As can be seen from Table 1, when methyl acrylate was not used as the monomer component of the copolymer (Comparative Example 1), the water immersion adhesive force was large, and the adhesive force change rate during water immersion was also large. Further, the adhesive layer remains 90% or more, and the degree of whitening is large. In addition, the peeled area rate at the time of skin application is large.
In place of methyl acrylate, when the same amount of methyl methacrylate as in Example 2 is used (Comparative Example 2), water resistance such as water adhesion and whitening resistance is improved. It can be seen that there are problems such as low, a large peeled area ratio at the time of skin application, and many subjects who feel uncomfortable.

  On the other hand, in this invention (Examples 1-3), the favorable result is obtained in all the evaluation test items. In particular, the rate of change in adhesive force during water immersion is small, whitening does not occur, and there is little or no adhesive layer remaining on the adherend. Therefore, it turns out that the adhesive composition for human body sticking of this invention has few changes of adhesive force under the influence of water, and has favorable water resistance. In addition, there is no peeling or discomfort to the skin, indicating a good pasting result.

Claims (7)

5 to 35% by weight of methyl acrylate, 60 to 90% by weight of (meth) acrylic acid ester having an alkyl group having 4 to 12 carbon atoms , and 2 to 15% by weight of acrylic acid and methacrylic acid in total An adhesive for sticking to the human body comprising a copolymer obtained by emulsion copolymerization using 0.5 to 5% by weight of a copolymerizable emulsifier with respect to the total amount of the monomer mixture. Copolymer emulsion. The copolymer for adhesives for human body sticking according to claim 1 , wherein the weight ratio of acrylic acid to methacrylic acid (acrylic acid / methacrylic acid) in the monomer mixture is in the range of 1/99 to 50/50. Emulsion. The copolymer emulsion for adhesives for human body sticking according to claim 1 or 2 , wherein the average particle size of the copolymer particles in the emulsion is in the range of 0.08 to 0.20 µm. A pressure-sensitive adhesive composition for human body application, comprising the copolymer emulsion for pressure-sensitive adhesive for human body application according to any one of claims 1 to 3 . The pressure-sensitive adhesive composition for human body sticking according to claim 4 , wherein the pressure-sensitive adhesive strength is in the range of 5 to 15 N / 25 mm, and the water immersion pressure-sensitive adhesive strength is in the range of 5 to 12 N / 25 mm. The pressure-sensitive adhesive composition for human body sticking according to claim 5 , wherein the absolute value of the rate of change in water-bonding adhesive strength is in the range of 0 to 60%. A patch for attaching a human body comprising a base material and an adhesive layer formed on at least one surface thereof using the adhesive composition for applying a human body according to any one of claims 4 to 6 .