JP2020179605A - Hydrous gel sheet - Google Patents

Abstract

To provide a hydrous gel sheet which has excellent productivity because of sufficient pot life during application and in which gelation proceeds sufficiently to avoid transfer to an adherend, thereby achieving good followability to the adherend.SOLUTION: A hydrous gel sheet includes a carboxyl group-containing polymer and a cross-linking agent to form an ionic bond with the carboxyl group-containing polymer. The hydrous gel sheet has a pH of not less than 1 and less than 3, and a moisture percentage of 1-30 mass%. Preferably, the hydrous gel sheet further includes 10-95 mass% of a drying adjustor in a total amount except for water.SELECTED DRAWING: None

Description

The present invention relates to a hydrogel sheet.

The hydrogel sheet having moderate adhesive strength and low skin irritation is used as a medical poultice, a medical electrode fixing material, a sheet-shaped skin cooling material, a wound dressing, and a sheet-shaped cosmetic pack.

The water-containing gel sheet is obtained by swelling a crosslinked or insolubilized hydrophilic polymer with water, and there are various types depending on the type of the hydrophilic polymer, the method of crosslinking or insolubilization, and the like. As a polymer used for a water-containing gel sheet, a carboxyl group-containing polymer such as polyacrylic acid or a salt thereof, a crosslinked product thereof, or carboxymethyl cellulose or a salt thereof is known. As a method for cross-linking a carboxyl group-containing polymer, a method of forming an ionic bond complex with a polyvalent metal cation such as aluminum hydroxide or aluminum sulfate is known, and this method is widely used industrially. ing.

However, when the above-mentioned polyvalent metal cation, which is generally used in the past, is mixed with an aqueous solution of a carboxyl group-containing polymer, the cross-linking reaction proceeds rapidly at room temperature to form a gel, so that the polyvalent metal cation and the carboxyl group are formed. The period during which the gel sheet forming mixture containing the contained polymer (hereinafter referred to as coating liquid) can be stored in a fluid state (hereinafter referred to as pot life) is shortened. Therefore, even if an attempt is made to process this coating liquid using a roll coater or the like, there is a problem that the coating cannot be performed because the crosslinking reaction has already proceeded and the fluidity has been lost.

In order to solve this problem, ethylenediaminetetraacetic acid (EDTA) or a chelating agent typified by a sodium salt thereof is added to the coating liquid as a gelation rate adjusting agent. The coating liquid to which the gelling rate adjusting agent is added can be coated using a roll coater or the like because the gelation reaction is delayed and the coating liquid has sufficient fluidity at the time of coating. However, since the effect of delaying the gelation reaction remains even after coating, there is a problem that it is necessary to keep the coated product for a long time without deforming it (hereinafter referred to as seasoning).

Therefore, in the prior art, it was common to process the coated hydrogel sheet as it is without winding it, but it is possible to wind the coated product of the hydrogel composition into a roll. If this is the case, the hydrogel sheet can be transported in roll form to the next process such as slitting and punching, which simplifies the manufacturing process and makes it possible to supply the product in roll form. The usefulness is significantly improved in comparison.

However, in the above-mentioned method generally used in the past, since a considerable amount of time is required for seasoning, there is a problem that it is necessary to wait for the completion of the cross-linking reaction of the hydrogel sheet before winding it into a roll. Further, if the base material is to be wound into a roll in a state where the cross-linking of the water-containing gel sheet is not perfect, there is a problem that the water-containing gel sheet protrudes from the roll due to the pressure at the time of winding.

Various methods have been studied in order to achieve both pot life and a rapid gelation reaction after coating. For example, in Patent Document 1, a coating liquid having a long pot life containing a cross-linking agent which does not cause a cross-linking reaction with a water-soluble polymer near room temperature but starts a cross-linking reaction by heating is applied to a base material. A method for cross-linking a hydrogel sheet by heating is described. However, under the conditions described in Patent Document 1, there is a problem in productivity because it takes an extremely high temperature and a long time to process the hydrogel sheet. Further, a cross-linking reaction is caused by adding a solid cross-linking agent in a dispersed state and dissolving by heating. However, since the particle size of the cross-linking agent affects the dissolution time of the cross-linking agent and the physical properties of the water-containing gel sheet, the obtained water-containing gel sheet can be obtained. There was a problem such as unstable quality.

Further, in Patent Document 2, an alkaline aqueous solution containing an anionic water-soluble polymer and an aluminum salt is prepared, and then an organic acid or an inorganic acid is added to dissolve the dissolved aluminum as an aluminate ion ([Al (OH)). 4] ^- ) is described as a method for arbitrarily adjusting the gelation rate by changing from aluminum ion (Al ³⁺ ). However, in order to achieve uniform gelation, it is necessary to dissolve the poorly water-soluble acid solid by heating, which has the same problem as in Patent Document 1. In addition, since the poorly water-soluble acid solid exemplified in Patent Document 2 dissolves slowly at room temperature, there is also a problem that the pot life cannot be sufficiently guaranteed.

These pot life problems are that when the carboxyl group-containing polymer is crosslinked with polyvalent metal cations, the carboxyl group-containing polymer is neutralized with an alkali or buffer, or a partially neutralized product of the carboxyl group-containing polymer. It is generated when the solution of the material is used at a pH close to neutral, such as by using a completely neutralized product. That is, it is difficult to obtain a hydrogel sheet having sufficient elasticity because an ionic bond with a polyvalent metal cation is not formed unless the carboxylic acid of the carboxyl group-containing polymer is ionized to some extent. It was a common technical knowledge of.

Japanese Unexamined Patent Publication No. 2000-318906 JP-A-11-199678

The problem to be solved by the present invention is that it has a sufficient pot life at the time of coating, so that it is excellent in productivity, and that gelation progresses sufficiently, so that it does not transfer to the adherend and becomes an adherend. It is an object of the present invention to provide a hydrogel sheet having good followability.

As a result of diligent studies to solve the above problems, the present inventors have found that the above problems can be solved, and have completed the present invention.

That is, the present invention is characterized in that it contains a carboxyl group-containing polymer and a cross-linking agent that ionically bonds with the carboxyl group-containing polymer, has a pH of 1 or more and less than 3, and has a water content of 1 to 30% by mass. Regarding the hydrogel sheet.

The present invention further relates to the above-mentioned hydrogel sheet containing 10 to 95% by mass of a drying modifier in the total amount excluding water.

According to the present invention, it is excellent in productivity by having a sufficient pot life at the time of coating, and there is no transfer to the adherend by sufficiently advancing gelation, and the followability to the adherend is good. It has become possible to provide a hydrogel sheet.

Hereinafter, embodiments of the present invention will be described in detail. In the following description, "%" means "mass%" unless otherwise specified.

The water-containing gel sheet of the present invention is a water-containing gel sheet containing a carboxyl group-containing polymer and a cross-linking agent that forms an ionic bond with the carboxyl group-containing polymer, having a pH of 1 or more and less than 3, and a water content of 1 to 30% by mass. ..

Examples of the carboxyl group-containing polymer used in the present invention include homopolymers of (meth) acrylic acid and synthetic polymers such as copolymers or salts thereof, hyaluronic acid, xanthan gum, gellan gum, pectin, caraginan, alginic acid, karaya gum and carboxymethyl cellulose. Examples include proteins such as polysaccharides and glycinin (soy protein). As the carboxyl group-containing polymer, one kind or two or more kinds of components can be used. Of these, polyacrylic acid or a salt thereof is preferably used.

As the carboxyl group-containing polymer used in the present invention, both a non-crosslinked polymer and a crosslinked polymer can be appropriately used. The non-crosslinked polymer is a polymer obtained from a monofunctional monomer and has a linear structure. The crosslinked polymer is a polymer obtained from a group of monomers containing a polyfunctional monomer and has a crosslinked structure.

The lower limit of the weight average molecular weight of the non-crosslinked carboxyl group-containing polymer used in the present invention is preferably 20,000 or more, more preferably 150,000 or more. The upper limit of the weight average molecular weight is not particularly limited, but is generally 5 million or less. By using a non-crosslinked carboxyl group-containing polymer having a weight average molecular weight of 20,000 or more, the gel strength required for sheet formation can be obtained.

The crosslinked carboxyl group-containing polymer preferably has a 0.2% neutralization viscosity at 20 ° C. of 1,500 mPa · s or more and 35,000 mPa · s or less, and more preferably 2,000 mPa · s or more and 30,000 mPa · s or less. .. Alternatively, the 0.5% neutralization viscosity at 20 ° C. is preferably 5,000 mPa · s or more and 75,000 mPa · s or less, and more preferably 5,400 mPa · s or more and 70,000 mPa · s or less. By using a crosslinked carboxyl group-containing polymer having a 0.2% neutralization viscosity at 20 ° C. of 1,500 mPa · s or more, or a 0.5% neutralization viscosity at 20 ° C. of 5,000 mPa · s or more. The gel strength can be improved. By using a crosslinked carboxyl group-containing polymer having a 0.2% neutralization viscosity at 20 ° C. of 35,000 mPa · s or less, or a 0.5% neutralization viscosity at 20 ° C. of 75,000 mPa · s or less. It is possible to suppress a decrease in handleability due to an increase in the viscosity of the coating liquid. The "0.2% neutralized viscosity" means the viscosity of the neutralized 0.2% by mass aqueous solution, and represents the value measured by the B-type viscometer.

Any amount of the non-crosslinked carboxyl group-containing polymer and the crosslinked carboxyl group-containing polymer can be added, but it is preferable to use both of them in combination because the gel strength can be further improved.

Examples of the cross-linking agent for ionic bonding with the carboxyl group-containing polymer include inorganic compounds that generate polyvalent metal cations such as aluminum chloride, zirconium chloride, magnesium chloride, and calcium chloride, 1,3-diaminoethane, and 4,4'. -Examples include organic compounds that generate polyvalent cations such as diaminodiphenylmethane and melamine. As the cross-linking agent, one kind or two or more kinds of components can be used. Of these, alum, which is an aluminum salt, is preferably used.

Any amount of the cross-linking agent can be added, but it is preferably 0.1 to 50%, more preferably 0.5 to 50%, based on 100% of the carboxyl group-containing polymer. When the amount of the cross-linking agent added is 0.1% or more, gelation proceeds rapidly as the water content decreases, and when it is 50% or less, a gel sheet having high transparency and excellent appearance can be produced.

If necessary, the hydrogel sheet may further contain a hydrophilic polymer other than the carboxyl group-containing polymer and the cross-linking agent, and other additives.

Examples of the hydrophilic polymer include nonionic synthetic polymers such as polyvinyl alcohol and polyvinylpyrrolidone, polyallylamine or salts thereof, polyethyleneimine or salts thereof, polyacrylamide or salts thereof, cationic synthetic polymers such as polydialyldimethylammonium and polyvinylpyridine, and the like. Examples include nonionic polysaccharides such as starch, locust bean gum, guar gum and tamarind seed gum, and cationic polysaccharides such as chitosan. Although these hydrophilic polymers do not contribute to the reaction with the cross-linking agent, the rheology of the coating liquid and the physical properties such as gel strength and adhesive strength of the hydrogel sheet can be adjusted according to the type and amount of the polymer to be added.

Other additives include dryness regulators, pH regulators, antioxidants, preservatives, UV absorbers, lubricants, colorants (dye or pigment), chemicals, fillers (particle or fibrous), conductivity imparting agents. And so on.

As the drying adjusting agent, a hydrophilic compound having a small influence on the viscosity of the coating liquid and having a weight average molecular weight of 10,000 or less can be used. Examples thereof include room temperature liquid compounds such as glycerin and polyethylene glycol, and sugars. By using the drying adjusting agent, it is possible to suppress a decrease in the usability of the gel due to excessive evaporation of water in the drying step, and further to suppress a change in the water content after producing the water-containing gel sheet.

The amount of the drying adjusting agent added is preferably 10 to 95%, more preferably 15 to 92%, based on the total amount of the hydrogel sheet excluding water. When it is 10% or more, overdrying can be suppressed, and when it is 95% or less, the gel has sufficient strength.

As the pH adjuster, in addition to a strong acid such as hydrochloric acid or sulfuric acid, a weak acid such as phosphoric acid having pKa capable of lowering the pH to less than 3 can be used. Any amount of pH adjuster can be added.

The pH of the hydrogel sheet is 1 or more and less than 3. When the pH is less than 3, the production of ionic carboxylic acid that contributes to the cross-linking reaction is suppressed, and the pot life can be guaranteed. Further, when the pH is 1 or higher, the ionic carboxylic acid required for gelation can be secured, and the addition of an excessive acid becomes unnecessary.

The water content in the water-containing gel sheet is 1 to 30%, more preferably 2 to 25%. The flexibility of the water-containing gel sheet can be ensured when the water content of the water-containing gel sheet is 1% or more. Further, the water-containing gel sheet of the present invention is gelled when the water content is 30% or less.

The water-containing gel sheet is coated and dried by applying a coating liquid on a base material such as a resin film, a natural fiber, a semi-synthetic fiber, a synthetic fiber, or a cloth or knitted fabric composed of a composite fiber thereof, a non-woven fabric, a paper, and a synthetic paper. It can be made by. These base materials may be subjected to surface treatment such as primer treatment or water repellent / hydrophilic treatment, or may be composited with the same type or different types of base materials. The thickness of the base material is not particularly limited, but is preferably 5 to 3000 μm.

The method of applying the aqueous solution for forming a water-containing gel sheet to the base material is not particularly limited as long as it can coat a fluid material, and for example, a roll coater, a knife coater, a gravure coater, a bar coater, a die coater or the like is used. The method can be mentioned.

The amount of the aqueous solution for forming a water-containing gel sheet coated on the base material is not particularly limited, but is preferably 10 to 2000 g / m ² .

The atmospheric temperature in the heating step is not particularly limited, but is preferably 50 ° C. to 200 ° C., more preferably 80 ° C. to 120 ° C. When the atmospheric temperature in the heating process is 50 ° C or higher, the coating liquid can be dried efficiently in a timely manner, and when it is 200 ° C or lower, a rapid change in moisture content is suppressed, and the appearance is poor due to the generation of bubbles and the gel is not good. It is possible to prevent homogenization.

As a method of winding the water-containing gel sheet laminate, a normal winder can be used. If necessary, a polyester film or the like may be laminated on the surface of the water-containing gel sheet laminate as a release material and wound together with the water-containing gel sheet laminate. This release material has a function of preventing the water-containing gel sheet from adhering to the back surface of the base material. The release material may be one that has been subjected to a release treatment by applying a silicone resin or the like.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
<Raw materials>
The raw materials for the gels used in the examples and comparative examples shown in Table 1 are as follows.
Non-crosslinked polyacrylic acid: Julimer AC-10SH (weight average molecular weight 1 million), Julimer AC-10H (weight average molecular weight 150,000), Julimer AC-10L (weight average molecular weight MW 20,000 to 30,000), Toa Synthetic Co., Ltd. Type Polyacrylic acid: Junron PW-120 (viscosity 8,000 to 20,000 mPa · s, 0.2% neutralization, 25 ° C.), Junron PW-312S (viscosity 15,000 to 25,000 mPa · s, 0. 2% neutralization, 25 ° C), Toa Synthetic Co., Ltd., Akpek HV-501E (viscosity 2,500 to 6,400 mPa · s, 0.2% neutralization, 20 ° C, viscosity 5,400 to 11,400 mPa · s) , 0.5% neutralization, 20 ° C.), Akpek HV-504E (viscosity 2,000-5,450 mPa · s, 0.2% neutralization, 20 ° C., viscosity 26,500-39,500 mPa · s, 0 .5% neutralization, 20 ° C., Akpek HV-505E (viscosity 20,000-30,000 mPa · s, 0.2% neutralization, 20 ° C., viscosity 40,000-60,000 mPa · s, 0.5 % Neutralization, 20 ° C.), Acpec HV-505ED (viscosity 15,000 to 30,000 mPa · s, 0.2% neutralization, 20 ° C., viscosity 40,000 to 70,000 mPa · s, in 0.5% Sum, 20 ° C), Sumitomo Seika Co., Ltd. Non-bridged sodium polyacrylate: Alonbis SX (weight average molecular weight 4-5 million), Toa Synthetic Co., Ltd.

Crosslinked sodium polyacrylate: Leosic 260H (viscosity 7,000 to 13,000 mPa · s, 0.5% neutralization, 25 ° C), Toa Synthetic Co., Ltd. Sodium carboxymethyl cellulose (non-crosslinked carboxyl group-containing polymer): Sun Rose F-150MC (weight average molecular weight 200,000, viscosity 1,200 to 1,800 mPa · s, 1%, 25 ° C), Nippon Paper Co., Ltd. Polyvinyl alcohol: Gosenol EG-40 (viscosity 40.0 to 46.0 mPa · s, 4%, 20 ° C), Nippon Synthetic Chemical Co., Ltd. Polyallylamine hydrochloride: PAA-HCL-10L (weight average molecular weight 150,000), Nittobo Medical Co., Ltd. Aluminum potassium sulfate dodecahydrate: Karimyouban, Taimei Chemicals Polyethylene glycol Co., Ltd .: Macrogol 400 (weight average molecular weight 400), Sanyo Kasei Kogyo Co., Ltd. Melamine, hydrochloric acid, glycerin: Reagent grade, Fujifilm Wako Pure Chemicals Co., Ltd.

<Manufacturing method>
The gel production methods used in the examples and comparative examples shown in Table 1 are as follows.
According to the compounding composition, the raw material was dissolved in purified water at room temperature to obtain a coating liquid. This was coated on a polyethylene terephthalate (PET) film with a knife coater so as to have a concentration of about 500 g / m ² , and then dried by heating to obtain a water-containing gel sheet. This was bonded to the peeling surface of the silicone peeling PET film, and wound into a roll to prepare a water-containing gel sheet laminate roll.

<Evaluation>
The evaluation methods of the coating liquid and the water-containing gel sheet used in the examples and comparative examples shown in Table 1 are as follows. The results are also shown.

(Pot life of coating liquid)
It was evaluated whether the coating liquid left at room temperature for 24 hours or 168 hours after preparation could be applied with a doctor blade. The evaluation was performed according to the following criteria.
◎: No thickening is observed, and it can be applied with a doctor blade. (Extremely good)
◯: Slight thickening was observed, but it is within the range that can be applied with a doctor blade. (Good)
×: It is thickened or gelled and cannot be applied with a doctor blade. (Defective)

(Degree of gelation of hydrogel sheet)
The state when the obtained hydrogel sheet was lightly pressed with a finger was visually observed. The evaluation was performed according to the following criteria.
⊚: Repels light pushing and does not transfer to fingers. (Extremely good)
◯: Some transfer and stringing are observed for light pushing, but there is repulsion and it is within the allowable range. (Good)
X: It is in a liquid state without repelling against a light push. (Defective)
-: Not subject to evaluation because coating is not possible due to liquid gelation. (Extremely bad)

(Followability of hydrogel sheet)
The followability when the obtained hydrogel sheet was attached to the skin was confirmed. The evaluation was performed according to the following criteria.
⊚: Soft and excellent in followability. (Extremely good)
◯: The followability is slightly inferior, but there is no problem in use. (Good)
X: Hard and poor followability. (Defective)
-: Not evaluated because it is in a liquid state. (Extremely bad)

(Resilience of hydrogel sheet)
The state when the obtained hydrogel sheet was strongly pressed with a finger was visually observed. The evaluation was performed according to the following criteria.
⊚: It deforms greatly in response to strong pushing, but restores to its original shape when the force is released. (Extremely good)
◯: Some deformation and resilience are observed with strong pushing, but the original shape eventually collapses. (Good)
Δ: The original shape collapses immediately after a strong push. (Available)
X: Does not deform with strong pushing. (Defective)
-: Not subject to evaluation because it is in a liquid state. (Extremely bad)

In each of Examples 1 to 42, the pot life of the coating liquid is sufficiently long, the cross-linking proceeds sufficiently through the drying step, and a water-containing gel sheet showing a good gelation degree and tactile sensation is produced without seasoning. I was able to. On the other hand, in Comparative Examples 1 to 15, defects were observed in any of the pot life, gelation degree, and tactile sensation of the coating liquid.

Claims (2)

A water-containing gel sheet containing a carboxyl group-containing polymer and a cross-linking agent that ionically bonds with the carboxyl group-containing polymer, having a pH of 1 or more and less than 3, and a water content of 1 to 30% by mass. The hydrogel sheet according to claim 1, further comprising a drying modifier in an amount of 10 to 95% by mass based on the total amount excluding water.