JP4222913B2 - Adhesive hydrogel - Google Patents

Description

The present invention relates to an adhesive hydrogel. The adhesive hydrogel of the present invention can be used as a base material for percutaneous absorption by impregnating a drug, as well as for a biological use such as a wound dressing material, a bioadhesive material or a bioelectrode, and for industrial measurement. It can be suitably used as an electrode material or an industrial adhesive material.

  Products such as bioelectrodes and adhesive tapes that use adhesive hydrogel are not unusual now. The advantage of hydrogel over a polyacrylic ester resin called a general adhesive is that it is less irritating to the skin. This is considered to be because a general adhesive material has high fluidity, so that it penetrates to the deep part of the skin keratin asperities, and when the adhesive material is peeled off, it is peeled off together with the keratin, so that inflammation is likely to occur. In the case of hydrogel, fluidity is limited by cross-linking, so that it does not penetrate deep into the stratum corneum, it is difficult to peel off the stratum corneum even during peeling, and the damage to the skin is low. However, the adhesive strength of hydrogel is usually considered to be weaker than that of a general adhesive material.

  One of the products using hydrogel is an electrode for a living body such as an electrode for electrocardiogram measurement. Recently, there is a strong tendency to select an electrode suitable for the user, and it is desired to control the adhesive strength of the hydrogel accordingly. In particular, infants, children, and elderly people with weak skin prefer to have a hydrogel that is gentle on the skin as an adhesive. A smaller electrode is also required in terms of area, but if the area becomes smaller, those with weak adhesive strength will be easily peeled off and stable measurement will not be possible. Therefore, there has been a demand for a hydrogel having high adhesiveness.

  The basic properties required for an adhesive include adhesive strength and cohesive strength. The adhesive force is a force generated by the contact between the adhesive and the adherend, and the cohesive force can be said to be a force with which the adhesive tries to maintain the shape. When the cohesive force is weaker than the adhesive force, the adhesive material breaks down on the balance surface with the adhesive surface, and a part of the adhesive remains on the adherend. Even with the same pressure-sensitive adhesive, the adhesive strength differs when the adherend is different. For example, the adhesive strength to stainless steel, the adhesive strength to human skin, and the adhesive strength to paper are different. However, since the cohesive force of the adhesive itself is universal if it is the same material, it is ideal that its absolute value is high. Moreover, the numerical value obtained by the measurement of adhesive force is an average value to the last, and the adhesive force in a minute range is different. It does not occur due to variations in the quality of the pressure-sensitive adhesive, but originates from the fact that the surface state of the adherend is not uniform.

Normally, the viscosity of the adhesive is due to the softness and fluidity of the resin itself, but in the case of hydrogel, the fluidity of the water-soluble resin as a solution in the solvent water. Due to the above, this fluidity is limited by crosslinking, imparting shape retention and elasticity, and developing a function as an adhesive. Accordingly, when the fluidity is high, the adhesiveness is developed, but there is almost no cohesive force and the adhesive does not function. On the other hand, when shape retention is imparted by crosslinking, there is a problem that fluidity is lowered and adhesive strength is impaired.

  Alternatively, it seems that the above problem can be solved by increasing the concentration and density of the resin, increasing the viscosity as a solution to limit fluidity, and lowering the degree of cross-linking. The water-soluble resin has a strong polarity, and as the concentration becomes higher, a pseudo-crosslinking action occurs in the resin, the gel itself becomes harder, and as a result, the adhesiveness is impaired. Therefore, it is necessary to soften the gel in order to achieve high adhesion, but the higher the adhesion, the lower the cohesive strength of the gel, the remaining gel when peeling from the adherend, and other adhesive strength such as reduced handling. Most physical properties are sacrificed.

Even hydrogels with weak cohesion have low adhesion to adhesive objects if they are weak, so there is no problem because they do not require a large force to peel off. It is a problem with adhesive materials that the cohesive force loses the adhesive force and breaks during peeling.
In other words, adhesiveness and cohesive strength are contradictory properties, but both performances are necessary properties for use as an adhesive material, so it has good cohesive strength and can be controlled to have high adhesiveness. A hydrogel has been desired. However, conventional high-viscosity hydrogels have high fluidity to penetrate deep into the stratum corneum, but because of their weak cohesion (force to resist peeling) When affixed to a highly adhesive object, the hydrogel partially cohesively breaks off and remains on the skin or adhesive object, so-called skin residue, gel residue, or hydrogel breakage.

  As a conventional wound dressing material, a polyvinyl alcohol derivative having a stilbazolium group-containing polyvinyl alcohol as a skeleton contains water in an amount of 70 to 95% by weight, and has a wavelength of 410 nm or less, preferably 345 to 405 nm. A wound dressing obtained by causing a gelation reaction by irradiating is provided (Patent Document 1). In addition, it is described that one or more of polyhydric alcohol, water-soluble polymer, water-absorbing resin and the like may be used in combination for the purpose of improving shape retention and providing tackiness as necessary.

Japanese Patent No. 3001695

In the wound dressing of Patent Document 1, a crosslinking reaction occurs by irradiating a mixed solution of a photo-functional polyvinyl alcohol polymer and water with ultraviolet rays, and a polymer matrix (here, the polymer matrix is a three-dimensional one). A hydrogel is obtained because a network polymer structure cross-linked to the above is formed.
However, in order to impart performance such as improved shape retention and tackiness to the polymer matrix that becomes the skeleton, a mixture with further addition of a water-soluble polymer was created, and an attempt was made to obtain a hydrogel by ultraviolet irradiation. In this case, it is difficult to make the mixed solution completely uniform because of mixing of the polymers, and the uniformity of the resulting hydrogel is lowered.

  In addition, as a conventional adhesive gel, a non-crosslinked water-soluble polymer having a weight average molecular weight of 4000 to 15000000 and water are contained in a polymer matrix obtained by copolymerizing a polymerizable monomer and a crosslinkable monomer. A retained adhesive gel is provided (Patent Document 2).

JP 2003-096431 A

The adhesive gel disclosed in Patent Document 2 is a non-crosslinked water-soluble polymer, a polymerizable monomer having one polymerizable carbon-carbon double bond in the molecule and a carbon-carbon having polymerizable properties in the molecule. It reacts with a crosslinkable monomer having two or more double bonds, and a non-crosslinked water-soluble polymer is introduced at the same time as the polymerization crosslinking reaction. However, there is a demand for a hydrogel having high tackiness while maintaining even better cohesive strength.

  The present invention prevents so-called skin residue and gel residue, suppresses the occurrence of hydrogel breakage, has good cohesive force, and can control adhesiveness, and has a uniform and stable structure. The object is to provide a hydrogel.

In Patent Document 1, a cross-linking reaction occurs by irradiating a mixed solution of a photo-functional polyvinyl alcohol polymer and water with ultraviolet rays, and a polymer matrix (here, the polymer matrix is a three-dimensionally cross-linked network shape). A hydrogel is obtained because the polymer structure is formed.
However, in order to give the skeleton polymer matrix performances such as improved shape retention and tackiness, a mixture with a water-soluble polymer is created and a hydrogel is obtained by UV irradiation. The mixed liquid is difficult to make completely uniform because of the mixing of the polymers, and the uniformity of the hydrogel to be produced is lowered. That is, for example, a polymerizable monomer having one polymerizable carbon-carbon double bond in the molecule and a crosslinkable monomer having two or more carbon-carbon double bonds having polymerizable in the molecule. Compared to a copolymerized cross-linked polymer matrix, the uniformity is poor. This is because it is clear that a monomer having a low molecular weight is mixed and dissolved more uniformly than a polymer having a high molecular weight, and a uniform polymer matrix is formed by subsequent polymerization.
Further, apart from the polymer matrix based on the polyvinyl alcohol-based derivative, it is not considered to add a polymer to give performance to produce a second polymer matrix, and even if an attempt is made to produce a polymer matrix, For this reason, two uniform polymer matrices cannot be obtained.

In Patent Document 2, a non-crosslinked water-soluble polymer is composed of two polymerizable monomers having one polymerizable carbon-carbon double bond in the molecule and two polymerizable carbon-carbon double bonds in the molecule. Reacts with two or more crosslinkable monomers, introduces a non-crosslinked water-soluble polymer at the same time as the polymerization crosslinking reaction, and has excellent releasability from the protective film and adhesive force without requiring complicated steps A hydrogel is obtained.
In the hydrogel of Patent Document 2, the effect of improving the cohesive force is not large only by adding a non-crosslinked water-soluble polymer. This is because even when a non-crosslinked water-soluble polymer is introduced into a polymer matrix produced by a polymerization crosslinking reaction, there is no strong interaction between the non-crosslinked water-soluble polymer and the polymer matrix.

In order to solve the above-mentioned problems, the adhesive hydrogel of the present invention has a nonionic polymerizable monomer having one polymerizable carbon-carbon double bond in the molecule and a polymerizable property in the molecule. A first polymer matrix obtained by copolymerization of a crosslinkable monomer having two or more carbon-carbon double bonds, a polyalkylene oxide having a weight average molecular weight of 300,000 to 3,000,000, and polyacrylic acid. A polyhydric alcohol and water are held in the second polymer matrix.

  This prevents so-called skin residue and gel residue, suppresses the occurrence of hydrogel breakage, and can control adhesiveness while maintaining good cohesive force, and has a uniform and stable structure. A gel can be provided.

Among them, as a preferred embodiment of the present invention, an IPN (Interpenetrating Polymer Network) in which a matrix having a relatively low crosslinking density and a matrix different from this are interpenetrated in order to produce a highly adhesive hydrogel while maintaining cohesive force. It is effective to form a structure. In order to form the IPN structure, a matrix once polymerized and cross-linked is impregnated with a new polymerizable monomer and a cross-linkable monomer, and the operation is performed again, or a prepolymer is used. Can be formed.
As a result, the hydrogel has higher cohesion than the single polymer matrix because the first and second polymer matrices interpenetrate each other and both polymer matrices have an IPN structure with a cross-linked structure. It becomes. Therefore, even if it is a highly adhesive hydrogel, when it is affixed to an adhesive object in the actual use stage and removed from the adhesive object for removal after use, for example, if the adhesive object is skin, so-called skin The rest will occur and no discomfort will occur.

  In addition, since the second polymer matrix made of polyalkylene oxide and polyacrylic acid can be formed at the same time as the first polymer matrix is formed by copolymerization crosslinking, no complicated process is required. The hydrogel having a uniform structure can be economically provided.

  The adhesive hydrogel of the present invention is obtained by copolymerizing a nonionic polymerizable monomer and a crosslinkable monomer to form a first polymer matrix (here, the polymer matrix is three-dimensionally crosslinked). And a second polymer matrix cross-linked with polyalkylene oxide and polyacrylic acid, and simultaneously introducing each cross-linked and interpenetrating IPN structure. Can be held.

  The first polymer matrix is formed by a copolymerization crosslinking reaction such as radical polymerization of a nonionic polymerizable monomer and a crosslinkable monomer. Since polyacrylic acid, polyalkylene oxide, and the like do not have radical polymerizability, they do not participate in this polymerization crosslinking and are not included in the copolymer.

  The second polymer matrix is formed by the reaction of polyalkylene oxide and polyacrylic acid. This is because the proton-accepting polymer polyalkylene oxide and the proton-donating polymer acrylic acid form an interpolymer complex through hydrogen bonds (Abe Yasuji: Polymer Complex, Kyoritsu Shuppan (1994)). The bond between the polyalkylene oxide and the polyacrylic acid is selectively performed.

  By forming the above two types of polymer matrix at the same time, the first polymer matrix and the second polymer matrix are each crosslinked and have a uniform IPN structure that interpenetrates. A hydrogel whose adhesiveness can be controlled is obtained.

  In addition, since the second polymer matrix made of polyalkylene oxide and polyacrylic acid can be formed at the same time as the first polymer matrix is formed by copolymerization crosslinking, no complicated process is required. The hydrogel having a uniform structure can be economically provided.

In the adhesive hydrogel of the present application, it is preferable to perform the reaction in weak acidity in consideration of the stability and safety of the generated hydrogel and skin irritation. However, after the hydrogel is formed, the pH is weakened with acid or alkali. It is also possible to adjust the acidity.

The nonionic polymerizable monomer in the present invention is not particularly limited as long as it has one polymerizable carbon-carbon double bond in the molecule and is water-soluble. Not. Here, water-soluble means that 10 g or more is dissolved in 100 g of water. For example, (meth) acrylamide represented by the structure of CH ₂ = CR ¹ CONR ² R ³ (R ¹ : H or CH ₃ , R ² and R ³ : C _n H _{2n + 1} (n is an integer of 0 to 4)). , N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, acrylamide derivatives such as N-isopropylacrylamide, vinylamide derivatives such as vinylpyrrolidone, vinylacetamide, vinylformamide, and nonionic such as allyl alcohol One or more monomers can be used.
Among these, since the polymerization reactivity is good, it is more preferable to use an acrylamide derivative because the polymerization reactivity point and the affinity with other components in the adhesive hydrogel are good.

  As the crosslinkable monomer in the present invention, N, N′-methylenebis (meth) acrylamide, N, N′-ethylenebis (meth) having two or more carbon-carbon double bonds having polymerizability in the molecule. Multifunctional (meth) such as acrylamide, (poly) ethylene glycol di (meth) acrylate, glycerin tri (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polyglycerin di (meth) acrylate One or more of acrylamide or (meth) acrylate tetraallyloxyethane, diallylammonium chloride and the like are preferable.

  As the polyhydric alcohol in the present invention, in addition to diols such as ethylene glycol, propylene glycol and butanediol, polyhydric alcohols such as glycerin, pentaerythritol and sorbitol, polyhydric alcohol condensation such as polyethylene glycol, polypropylene glycol and polyglycerin Polyhydric alcohol modified products such as polyoxyethylene glycerin can be used, but liquid polyhydric alcohol is used in the temperature range where the gel body is actually used (for example, around 20 ° C. when used indoors) It is preferable to do. Polyhydric alcohol can be used as 1 type, or 2 or more types of liquid mixture, or a liquid mixture of a polyhydric alcohol and water.

  As the polyalkylene oxide in the present invention, polyethylene oxide, polypropylene oxide or the like can be used alone or in combination, but a copolymer of two or more kinds of polyalkylene oxides such as polyethylene oxide / propylene oxide can also be used.

  Examples of the polyalkylene oxide include polyethylene oxide and polypropylene oxide. The weight average molecular weight is preferably 300,000 to 3,000,000, and 600,000 to 2.4 million is optimal. In particular, polyethylene oxide is suitable as the polyalkylene oxide.

  Polyalkylene oxide is defined as polyalkylene glycol (polyethylene glycol or polypropylene glycol having a weight average molecular weight of up to several thousand) having a high molecular weight (generally having a weight average molecular weight of about 80,000 or more). Its characteristics are very different from those of polyalkylene glycol, and it exhibits behavior as a water-soluble polymer, not as a polyhydric alcohol. When the molecular weight is less than 300,000, the second polymer matrix is too small relative to the first polymer matrix, and the effect of increasing the cohesive force cannot be obtained. Conversely, when the molecular weight exceeds 3 million, the viscosity increase is large. Since it is difficult to prepare a uniform liquid mixture, it is difficult to form a uniform polymer matrix, and it is difficult to obtain a uniform hydrogel. If a small amount is added to suppress an increase in viscosity, a sufficient polymer matrix cannot be formed, and thus the effect of increasing the cohesive force cannot be obtained.

  The polymerization degree of the polyacrylic acid in the invention is preferably 1000 to 100,000 in terms of weight average molecular weight, and more preferably 2,000 to 100,000.

  In general, when polyacrylic acid is added to impart tackiness, it is said that tackiness does not develop in low molecular weight materials, and is obtained by crosslinking polyacrylic acid such as a poultice with a polyvalent metal or the like. The molecular weight of polyacrylic acid usually used for obtaining adhesiveness is a high molecular weight product having a molecular weight of 1 million or more. According to the present invention, when the molecular weight is less than 1000, the formation of the polymer matrix is insufficient and the effect of increasing the cohesive force cannot be obtained. According to the present invention, a sufficient effect is obtained when the molecular weight of the polyacrylic acid is less than 100,000, which is different from general tackiness addition by adding polyacrylic acid. When the molecular weight exceeds 100,000, the viscosity increases and it is difficult to prepare a uniform liquid mixture. Therefore, it is difficult to form a uniform polymer matrix, and it is difficult to obtain a uniform hydrogel. In addition, if a small amount of high molecular weight polyacrylic acid is added to suppress an increase in viscosity, a sufficient polymer matrix is not formed, and thus the effect of increasing the cohesive force is difficult to obtain.

  A conductive gel body can be obtained by adding an electrolyte to the adhesive hydrogel of the present invention. For example, when used as a bioelectrode such as an electrocardiogram measurement electrode, a low-frequency treatment device electrode, and various ground electrodes, the specific resistance is preferably 0.1 to 10 kΩ · cm.

  The electrolyte includes alkali metals such as lithium, sodium and potassium, halides of alkaline earth metals such as magnesium and calcium, mineral salts such as carbonic acid, sulfuric acid and phosphoric acid, as well as salts derived from organic acids and ammonium A salt that can be used and is neutral to slightly acidic is preferred.

  The addition amount of the polyalkylene oxide contained in the adhesive hydrogel of the present invention is preferably 0.05 to 5 parts by weight with respect to 20 parts of the nonionic polymerizable monomer, and 0.2 to 2 parts by weight. More preferably, it is a part. In order to form a polymer matrix and obtain a sufficient effect, an addition amount of 0.05 parts by weight or more is preferable. Further, when added at a concentration exceeding 5 parts by weight, the effect of improving the shape retention is stronger than the cohesive force, and it is difficult to obtain high adhesiveness.

  The addition amount of polyacrylic acid contained in the adhesive hydrogel of the present invention is preferably 0.05 to 5 parts by weight with respect to 20 parts of the nonionic polymerizable monomer, and 0.2 to 2 parts by weight. More preferably, it is a part. In order to form a polymer matrix and obtain a sufficient effect, an addition amount of 0.05 parts by weight or more is preferable. Moreover, when it adds exceeding 5 weight part, the effect of a shape retention improvement becomes stronger than cohesion force, and it is difficult to obtain high adhesiveness.

  The ratio (weight ratio) of polyalkylene oxide and polyacrylic acid is preferably 1/10 to 10/1. When the weight ratio is within this range, the second polymer matrix is formed, and the effect of increasing the cohesive force is obtained.

  The amount of water contained in the adhesive hydrogel of the present invention is preferably 10 to 60 parts by weight and more preferably 15 to 40 parts by weight with respect to 20 parts of the nonionic polymerizable monomer. preferable. When the addition amount is less than 10 parts by weight, it is difficult to dissolve water-soluble polymers such as polyalkylene oxide and polyacrylic acid sufficient to improve the mechanical strength. On the other hand, when the gel body is prepared with the added amount of water exceeding 60 parts by weight, the water-soluble component is easily dissolved, but the water content greatly exceeds the amount of water that can be retained by the polymer matrix. Is likely to occur.

  The addition amount of the polyhydric alcohol contained in the adhesive hydrogel of the present invention is preferably 30 to 70 parts by weight, and 40 to 60 parts by weight with respect to 20 parts of the nonionic polymerizable monomer. More preferred. When the addition amount of the polyhydric alcohol is 30 parts by weight or more, a change in physical properties due to drying of the obtained gel body is small, and high adhesive strength is obtained.

  The addition amount of the crosslinkable monomer contained in the adhesive hydrogel of the present invention varies depending on the nonionic polymerizable monomer species and the crosslinkable monomer species to be used, but in general nonionic polymerization The amount is preferably 0.002 to 0.1 parts by weight and more preferably 0.01 to 0.05 parts by weight with respect to 20 parts of the functional monomer. When the concentration of the crosslinkable monomer is 0.1 parts by weight or less, a highly tacky hydrogel is obtained. On the other hand, when the concentration of the crosslinkable monomer is 0.002 parts by weight or more, shape retention and cohesion as a hydrogel can be obtained.

Therefore, although not particularly limited, specifically, a nonionic polymerizable monomer having one polymerizable carbon-carbon double bond in the molecule and a polymerizable carbon in the molecule. -Water and polyhydric alcohol in the first polymer matrix copolymerized with a crosslinkable monomer having two or more carbon double bonds and the second polymer matrix made of polyalkylene oxide and polyacrylic acid Is held,
For 20 parts by weight of the nonionic polymerizable monomer,
a) 0.05-5 parts by weight of the polyalkylene oxide b) 0.05-5 parts by weight of the polyacrylic acid c) 10-60 parts by weight of the water d) 40-70 parts by weight of the polyhydric alcohol e) An adhesive hydrogel characterized in that the crosslinkable monomer is contained in an amount of 0.002 to 0.1 parts by weight.

  When an electrolyzed hydrogel is obtained by adding an electrolyte, the amount of electrolyte added is preferably 0.05 to 10 parts by weight with respect to 20 parts of the nonionic polymerizable monomer. -5 parts by weight is preferred. When the amount of electrolyte added is less than 0.05 parts by weight, it is difficult to reduce the impedance of the gel body, and there is virtually no difference from the case where no electrolyte is added. On the other hand, when the amount of electrolyte added exceeds 10 parts by weight, it cannot be dissolved uniformly in the gel, salt is likely to precipitate, and undissolved residue is likely to occur.

Although it does not specifically limit as a method of manufacturing the adhesive hydrogel of this invention, For example, at least,
A nonionic polymerizable monomer (A) having one carbon-carbon double bond having polymerizability in the molecule;
A crosslinkable monomer (B) having two or more carbon-carbon double bonds having polymerizability in the molecule;
Polyalkylene oxide;
With polyacrylic acid,
water and,
Polyhydric alcohol,
By heating or irradiating the monomer compounded solution in which the polymerization initiator is uniformly mixed and dissolved,
A first polymer matrix obtained by copolymerization crosslinking of the nonionic polymerizable monomer (A) and the crosslinkable monomer (B), which retains the water and the polyhydric alcohol; the polyalkylene oxide; It can be obtained by forming a second polymer matrix made of polyacrylic acid.

  Since the monomer compounded liquid is liquid, for example, if it is poured into a molded resin mold and polymerized and crosslinked, a gel body having an arbitrary shape can be produced. Moreover, a sheet-like gel body can be obtained by pouring the compounded liquid between two films held in a certain gap to cause polymerization crosslinking.

The polymerization initiator is not particularly limited, but an azo polymerization initiator such as azobiscyanovaleric acid or azobisamidinopropane dihydrochloride can be used when polymerized and crosslinked by heating. In the case of polymerizing by irradiation with light, known photopolymerization initiators such as azo series and acetophenone series can be used. Further, a plurality of these initiators may be mixed, and light irradiation and heating may be performed simultaneously.
A redox initiator composed of a reducing agent such as ferrous sulfate or pyrosulfite and a peroxide such as hydrogen peroxide or peroxodisulfate can also be used. When these redox initiators are used, it is possible to carry out the reaction without heating, but it is preferable to carry out heating in order to reduce the residual monomer and shorten the reaction time.
In addition, polymerization crosslinking by irradiating radiation such as electron beam or gamma ray is possible, but it is not preferable because special equipment for radiation irradiation is required. The adhesive hydrogel of the present invention can be obtained by a method other than such a special production method.

  When this production method is used, the production process is simple and very economical, and at the same time, a gel body having stable physical properties can be obtained.

  In addition, the adhesive hydrogel in the present invention may contain antiseptics, bactericides, anticorrosives, rust inhibitors, antioxidants, antifoaming agents, stabilizers, fragrances, surfactants, colorants, etc. Anti-inflammatory agents, vitamin agents, whitening agents and other medicinal ingredients may be added as appropriate.

  Examples of the method of adding the medicinal component include a method of forming a polymer matrix by dissolving or dispersing in a compounding solution in advance, and a method of adding to a once produced adhesive hydrogel. Among these methods, the former method is more preferably added by the latter method because the medicinal component may be attacked by radicals and lose its medicinal effect during gel formation accompanied by radical polymerization reaction.

[Examples and Comparative Examples]

20 parts by weight of acrylamide as a nonionic polymerizable monomer, 0.02 parts by weight of N, N′-methylenebisacrylamide as a crosslinkable monomer, 55 parts by weight of glycerin as a polyhydric alcohol, as an electrolyte salt 5 parts by weight of sodium chloride, 0.4 parts by weight of polyethylene oxide having a weight average molecular weight of 1 million as polyalkylene oxide, 0.4 parts by weight of polyacrylic acid having a weight average molecular weight of 4000 as polyacrylic acid, 19.2 parts by weight of water was mixed, dissolved and stirred to obtain a monomer compounded solution. Next, 0.3 parts by weight of 1-hydroxy-cyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator was added to the monomer compounded solution, and further dissolved by stirring. . Next, the monomer mixture is poured into a polycarbonate mold (130 mm × 130 mm, thickness 1.0 mm) on a 100 μm thick biaxially stretched polyester film that has been subjected to silicon treatment on glass, and further onto the mold A 38 μm biaxially stretched polyester film subjected to silicon treatment was placed so as not to contain air bubbles, and quartz glass was placed thereon to control the thickness. This was taken out by irradiating an ultraviolet lamp with a peak intensity of 50 mW / cm ² for 60 seconds and cut out from a mold to obtain a sheet-like adhesive hydrogel sample of Example 1.

  A sheet-like adhesive hydrogel sample of Example 2 was obtained in the same manner as Example 1 except that 2 parts by weight of polyethylene oxide having a weight average molecular weight of 1,000,000 was used as the polyalkylene oxide.

  A sheet-like adhesive hydrogel sample of Example 3 was obtained in the same manner as Example 1 except that 0.2 parts by weight of polyethylene oxide having a weight average molecular weight of 2.4 million was used as the polyalkylene oxide.

  A sheet-like adhesive hydrogel sample of Example 4 was obtained in the same manner as in Example 1 except that 2 parts by weight of polyethylene oxide having a weight average molecular weight of 600,000 was used as the polyalkylene oxide.

  A sheet-like adhesive hydrogel sample of Example 5 was obtained in the same manner as Example 1 except that polyacrylic acid having a weight average molecular weight of 4000 was changed to 2 parts by weight as polyacrylic acid.

  A sheet-like adhesive hydrogel sample of Example 6 was obtained in the same manner as in Example 1 except that 0.2 parts by weight of polyacrylic acid having a weight average molecular weight of 100,000 was used as polyacrylic acid.

  A sheet-like adhesive hydrogel sample of Example 7 was obtained in the same manner as in Example 1 except that 2 parts by weight of polyacrylic acid having a weight average molecular weight of 2000 was used as polyacrylic acid.

  A sheet-like adhesive hydrogel sample of Example 8 was obtained in the same manner as in Example 1, except that 20 parts by weight of N, N′-dimethylacrylamide was used instead of acrylamide as the nonionic polymerizable monomer. .

  A sheet-like adhesive hydrogel sample of Example 9 was obtained in the same manner as in Example 1 except that 0.4 parts by weight of polypropylene oxide having a weight average molecular weight of 1,000,000 was used as the polyalkylene oxide.

  A sheet-like adhesive hydrogel sample of Example 10 was obtained in the same manner as Example 1 except that the sodium chloride was changed to 2.5 parts by weight.

  A sheet-like adhesive hydrogel sample of Example 11 was obtained in the same manner as Example 1 except that sodium chloride was not added.

[Comparative Example 1]
20 parts by weight of acrylamide as a nonionic polymerizable monomer, 0.04 parts by weight of N, N′-methylenebisacrylamide as a crosslinkable monomer, 55 parts by weight of glycerin as a polyhydric alcohol, as an electrolyte salt 5 parts by weight of sodium chloride and 19.2 parts by weight of water as a solvent were mixed and dissolved and stirred to obtain a monomer compounded solution. Next, 0.3 parts by weight of 1-hydroxy-cyclohexyl phenyl ketone (trade name Irgacure 184, manufactured by Ciba Specialty Chemicals) is added as a photopolymerization initiator to 100 parts by weight of the monomer compounded solution, and further stirred. And dissolved. Next, the monomer mixture is poured into a polycarbonate mold (130 mm × 130 mm, thickness 1.0 mm) on a 100 μm thick biaxially stretched polyester film that has been subjected to silicon treatment on glass, and further onto the mold A 38 μm biaxially stretched polyester film subjected to silicon treatment was placed so as not to contain air bubbles, and quartz glass was placed thereon to control the thickness. This was taken out by irradiating it with an ultraviolet lamp having a peak intensity of 50 mW / cm 2 for 60 seconds and cut out from the mold to obtain a sheet-like adhesive hydrogel sample of Comparative Example 1.

[Comparative Example 2]
A sheet-like adhesive hydrogel sample of Comparative Example 2 was obtained in the same manner as Comparative Example 1 except that 0.4 parts by weight of polyacrylic acid was added.

[Comparative Example 3]
A sheet-like adhesive hydrogel sample of Comparative Example 3 was obtained in the same manner as Comparative Example 1, except that 0.4 part by weight of polyalkylene oxide was added.

[Comparative Example 4]
Comparative Example 4 is the same as Comparative Example 1 except that 0.8 part by weight of Polypyrrolidone (PVP); Colloidon K-90 (weight average molecular weight: 1100000) manufactured by BASF as a non-crosslinked water-soluble polymer is added. A sheet-like adhesive hydrogel was obtained.

  Since the cohesive strength of the hydrogel appears as a force against the peeling when the hydrogel peels, the following evaluation was performed.

[90 degree adhesive strength]
A sample is cut into a strip of 20 mm x 100 mm, this test piece is attached to a stainless steel plate, set on a rheometer manufactured by Sun Science Co., Ltd., and peeled in a 90-degree direction at a speed of 300 mm / min according to JIS-Z0237. Then, 90 degree adhesive strength measurement was performed. If it is about 400 g or more as a hydrogel, it will adhere | attach strongly on skin etc. as a highly adhesive gel. The measurement results are shown in Table 1.

[Gel breaking strength]
The hydrogel of the said Example and the comparative example was cut out to width 20mm and length 50mm to make a sample piece, and thickness was calculated | required with the thickness gauge. The tensile strength at break was measured for Examples 1 to 11 and Comparative Examples 1 to 4. The top and bottom of the sample piece is fixed to the jig of a measuring instrument (Rheometer, CR-150, manufactured by Sun Science Co., Ltd.), the other piece is pulled in the length direction at a speed of 300 mm / min, the maximum load at break and the sample The tensile strength at break was determined from the thickness of the piece. The results are shown in Table 1.

[Overhead]
The cohesive force was evaluated by measuring the protrusion of hydrogel to the compression stress. First, a sample was cut into a 20 mmφ cylindrical shape (thickness 1 mm), the film on one side of this test piece was peeled off, and Toyobo's peach coat SE80 (hereinafter referred to as peach coat) was used so that the gel would not easily shift or slip. Pasted on top. Since the surface of the peach coat has an uneven structure, the hydrogel penetrates to produce an anchor effect, and the adhesion surface area is increased, so that the peach coat adheres very strongly to the hydrogel. Further, a flat polycarbonate plate (thickness 1 mm) was placed on the surface opposite to the gel application surface, and a 10 kgf weight was placed on the polycarbonate plate and left for 48 hours. The hydrogel adheres well to the peach coat, and once adhered, it does not easily peel off, so that it sticks to the peach coat while protruding after the stress is removed. After standing for 48 hours, the weight and the polycarbonate plate were removed, and the maximum diameter of the gel that protruded under pressure stress on the peach coat was measured, and the gel protrusion width was calculated from the difference from the initial diameter. The measurement results are shown in Table 1.

[Peel strength]
The hydrogel of the said Example and the comparative example was cut out in 20 mm x 120 mm strip shape, and the peach coat was affixed on both surfaces of hydrogel. Since the surface of the peach coat has a minute uneven structure, the hydrogel penetrates to produce an anchor effect, and since the adhesion surface area is increased, it strongly adheres to the hydrogel. And about Examples 1-11 and Comparative Examples 1-4, the single side | surface peach coat surface is fixed on a stainless steel plate with a double-sided adhesive tape, and a hydrogel and the other peach coat are measured with a measuring instrument (Leon made by Sun Scientific Co., Ltd.). Peach fixed with hydrogel and peach coat together according to 90 degree peeling method described in JIS adhesive tape / adhesive sheet test method Z0237-1980 Removed from the coat. The stress at this time is shown in Table 1 as the peel strength.

  As for the comparative example, the cohesive force is made to be the same level as in the examples, so the amount of the crosslinkable monomer added is increased and the crosslink density is increased, so the results of tensile rupture strength, protrusion and peel strength as cohesive force Are the same values in both the examples and comparative examples. Thereby, although an Example and a comparative example are considered to have the same cohesive force, when a 90 degree | times adhesive force is compared, a comparative example is clearly lower than an Example and high adhesiveness is obtained. On the other hand, it turns out that an Example is a hydrogel which has both cohesion force and high adhesiveness.

  Next, the electrical conductivity of the hydrogels of Examples and Comparative Examples was evaluated by specific resistance. That is, for Examples 1, 10, and 11, samples were cut into 20 mm squares, stainless steel plates were bonded to both sides of the test piece, and the impedance when a current of 1 kHz, 10 Vp-p was passed between the stainless steel plates was measured. The specific resistance was calculated from the area and gel thickness. If it is 0.1-10 kohm * cm, it can be used for a bioelectrode etc.

Regarding specific resistance, Example 11 is 28 kΩ · cm because no electrolyte is added, but other examples are 0.1 to 10 kΩ · cm. It shows that by adding an electrolyte, conductivity performance is imparted to a hydrogel having both cohesive strength and high adhesiveness, and the conductivity performance can be controlled by the amount added as in Example 10. Yes.
Therefore, when applying this hydrogel to biomedical electrodes such as electrocardiogram measurement electrodes, it is possible to select an electrode suitable for the user, and since it is highly adhesive and difficult to peel off, the area is further increased. It can be designed as a small electrode, and can be suitably used particularly for infants and pediatric biomedical electrodes.

  In addition, Example 11 demonstrates sufficient performance for the use which does not require electroconductivity. Rather, it does not contain electrolytes.For example, when it is used for bandages, adhesive tapes, wound dressings, etc. that are applied to the skin for a long time, or when it is used for a long time in contact with metal, it is irritating to the skin and corrosive to metals. There is also a preferable case.

The adhesive hydrogel of the present invention can be used as a base material for percutaneous absorption by impregnating a drug, as well as for a biological use such as a wound dressing material, a bioadhesive material or a bioelectrode, and for industrial measurement. It can be used as an electrode material or an industrial adhesive material.

Claims (6)

Acrylamide derivatives , which are nonionic polymerizable monomers having one carbon-carbon double bond having a polymerizable property in the molecule, and crosslinkability having two or more carbon-carbon double bonds having a polymerizable property in the molecule. A first polymer matrix copolymerized with a polyfunctional (meth) acrylamide monomer, a second polymer matrix made of polyalkylene oxide having a weight average molecular weight of 300,000 to 3,000,000 and polyacrylic acid And an adhesive hydrogel characterized in that polyhydric alcohol and water are retained.   The adhesive hydrogel according to claim 1, wherein the polyalkylene oxide is polyethylene oxide.   The pressure-sensitive hydrogel according to claim 2, wherein the polyacrylic acid has a weight average molecular weight of 1,000 to 100,000.   The adhesive hydrogel according to any one of claims 1 to 3, comprising an electrolyte salt and having a specific resistance of 0.1 to 10 kΩ · cm. Acrylamide derivatives , which are nonionic polymerizable monomers having one carbon-carbon double bond having a polymerizable property in the molecule, and crosslinkability having two or more carbon-carbon double bonds having a polymerizable property in the molecule. A first polymer matrix copolymerized with a polyfunctional (meth) acrylamide monomer and a second polymer matrix made of polyalkylene oxide and polyacrylic acid having a weight average molecular weight of 300,000 to 3,000,000 In addition, polyhydric alcohol and water are retained,
For 20 parts by weight of the nonionic polymerizable monomer,
a) 0.05-5 parts by weight of the polyalkylene oxide b) 0.05-5 parts by weight of the polyacrylic acid c) 10-60 parts by weight of the water d) 40-70 parts by weight of the polyhydric alcohol e) The adhesive hydrogel characterized in that 0.002 to 0.1 parts by weight of the crosslinkable monomer is contained. at least,
An acrylamide derivative (A) which is a nonionic polymerizable monomer having one carbon-carbon double bond having a polymerizable property in the molecule;
Polyfunctional (meth) acrylamide (B) which is a crosslinkable monomer having two or more carbon-carbon double bonds having polymerizable properties in the molecule;
A polyalkylene oxide having a weight average molecular weight of 300,000 to 3,000,000,
With polyacrylic acid,
water and,
Polyhydric alcohol,
By heating or irradiating the monomer compounded solution in which the polymerization initiator is uniformly mixed and dissolved,
A first polymer matrix obtained by copolymerization crosslinking of the nonionic polymerizable monomer (A) and the crosslinkable monomer (B), which retains the water and the polyhydric alcohol; the polyalkylene oxide; A method for producing an adhesive hydrogel, comprising: forming a second polymer matrix made of polyacrylic acid.