Crosslinkable pressure-sensitive adhesive for skin

Abstract

It is an object of the invention to provide a crosslinkable pressure-sensitive adhesive for skin that exhibits satisfactory adhesion and releasability for human skin and low irritation to skin, and a crosslinkable pressure-sensitive adhesive sheet for skin that is suitable for medical and cosmetic use, as well as to provide a composition for production of a crosslinkable pressure-sensitive adhesive for skin that has superior storage properties and is suitable for preparation of the crosslinkable pressure-sensitive adhesive for skin. The crosslinkable pressure-sensitive adhesive for skin of the invention is formed by 100 parts by weight of an acrylic copolymer (copolymer A) comprising a (meth) acrylic acid alkyl ester as the main constituent component and 3-45 wt % diacetoneacrylamide as an essential constituent component, and containing no free carboxyl groups, and 0.1-30 parts by weight of an acrylic copolymer (copolymer B) comprising a (meth)acrylic acid alkyl ester as the main constituent component and a primary amino group and / or carboxyhydrazide group on a side chain, and containing no free carboxyl groups. A composition of copolymer A and copolymer B dissolved in a solvent containing at least 5.0 wt % acetone and / or butanone with respect to the total amount of solvent can be stored for prolonged periods.

Description

TECHNICAL FIELD [0001] The present invention relates to a crosslinkable pressure-sensitive adhesive for skin, to a crosslinkable pressure-sensitive adhesive sheet for skin employing it, to a composition for production of the crosslinkable pressure-sensitive adhesive for skin and to a process for production of the crosslinkable pressure-sensitive adhesive for skin. BACKGROUND ART [0002] Pressure-sensitive adhesive sheets for skin, in general, must reliably adhere for about 24 hours after being attached to skin and must also adhere without peeling during perspiration and bathing. Also for removal, they must be peelable with a degree of force that does not cause pain, and if the adhesion is stronger than necessary it can result in plucking of hairs and peeling of the corneum, as well as mechanical skin irritation by pulling of the skin. Consequently, this creates erythema that may persist for several days even after peeling, and therefore it is necessary to minimize this inconvenience....

AI Technical Summary

Benefits of technology

[0016] According to the invention, there is provided a crosslinkable pressure-sensitive adhesive for skin that has satisfactory adhesion and release properties for skin and low irritation to skin without using low molecular crosslinking agents, and a pressure-sensitive adhesive sheet for skin suitable for medical or cosmetic use. There is further provided a composition for production of a crosslinkable pressure-sensitive adhesive for skin that is stable even with prolonged storage. The crosslinkable pressure-sensitive adhesive for skin of the invention has the following features. (1) Since copolymer A does not contain acrylic acid, does not have the excessively strong cohesion of acrylic acid-based pressure-sensitive adhesives and produces no carboxylic acid-induced skin irritation, it is therefore suitable for adhesion to skin. (2) When using a drug, the basic drug usually interacts with the acrylic acid in the acrylic acid-containing pressure-sensitive adhesive resulting in impaired stability or lowered percutaneous absorption property, but since the pressure-sensitive adhesive of the invention contains no acrylic acid such inconveniences do not arise. (3) Because a large amount of isocyanate-based crosslinking agent is not used as the crosslinking agent, there is no loss of stability due to reaction with the drug.BRIEF EXPLANATION OF THE DRAWINGS

[0017]FIG. 1 is a graph showing the results of evaluating percutaneous absorption of oxybutynin using rat skin.

[0018]FIG. 2 is a graph showing the results of evaluating percutaneous absorption of tulobuterol using rat skin.

Problems solved by technology

Also for removal, they must be peelable with a degree of force that does not cause pain, and if the adhesion is stronger than necessary it can result in plucking of hairs and peeling of the corneum, as well as mechanical skin irritation by pulling of the skin.

Such crosslinking is achieved almost entirely by using the acrylic acid in an acrylic copolymer, but its drawbacks include the facts that (1) the adhesion is excessively strong or chemical activity of the acrylic acid causes significant skin irritation, (2) in percutaneous absorption preparations containing drugs, the acrylic acid and basic drug interact and impede migration of the drug from the pressure-sensitive adhesive into the skin, thereby reducing the percutaneous absorption, and (3) polyisocyanate used as the crosslinking agent is highly active and often reacts with drugs, thereby impairing drug stability.

However, while percutaneous absorption preparations using this type of pressure-sensitive adhesive have satisfactory drug percutaneous absorption and stability, the cohesive strength is insufficient when softening agents and plasticizers are added to improve the drug release property, and therefore adhesive residue remains on the skin after the percutaneous absorption preparation is removed.

With such percutaneous absorption preparations, however, it is possible to increase the shape retention of the pressure-sensitive adhesive layer but difficult to design a preparation with balance between adhesion on the skin and cohesive force of the pressure-sensitive adhesive.

However, the drawbacks of this method are the following: (1) Mixture of the low-molecular polyamine such as adipic acid dihydrazide or hexanediamine with the pressure-sensitive adhesive solution results in a coating mixture that gels within several hours and becomes impossible to coat.

Consequently, its use in a large amount promotes precipitation of polymers and renders handling inconvenient.

(4) Hydrazine compounds such as adipic acid dihydrazide are absorbed through the skin and are indicated as a toxicity risk, for which reason they have been unsuitable as additives for pressure-sensitive adhesives on skin.

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