Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-08-28
2003-10-07
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S098000, C525S099000
Reexamination Certificate
active
06630536
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive tape or sheet using the same. More specifically, it relates to a pressure-sensitive adhesive composition, and a pressure-sensitive adhesive tape or sheet to be used optimally for the external application in the field of medical hygiene, sports, and the beauty and health, as a first aid adhesive tape, a large size adhesive plaster, or a dressing material.
2. Description of the Related Art
In a pressure-sensitive adhesive composition provided for the application in a form of a pressure-sensitive adhesive tape or sheet, the adhesive property with respect to an adherend, the adhesive property (anchoring property) with respect to a backing film surface, and the cohesive property in a pressure-sensitive adhesive layer should be balanced. By balancing the same, quick contact and adhesion to an adherend can be enabled as well as the pressure-sensitive adhesive tape or sheet can be peeled off at the time of peeling and removing the same from the adherend neatly without the so-called adhesive residue phenomenon of leaving the pressure-sensitive adhesive on the surface of the adherend.
Moreover, the pressure-sensitive adhesive composition can be, in general, divided into an acrylic based adhesive and a rubber based adhesive on the whole. The acrylic based adhesive can be obtained by polymerization of an acrylic acid ester based monomer used as the main component monomer. Since a pressure-sensitive adhesive composition can be obtained according to the demanded characteristics, it is used widely.
In contrast, the rubber based adhesive can be divided into a natural rubber based one and a synthetic rubber based one on the whole. Compared with the acrylic based adhesive, it has a superior adhesive property. Moreover, it can be produced easily only by mixing materials as well as it has a relatively good reproductivity.
Such a rubber based adhesive, in general, comprises a rubber component and a tackifier as the main component, and optionally other materials such as a softening agent and a filler. That is, a pressure-sensitive adhesive composition is provided by adding a tackifier having a high glass transition temperature to the rubber component, which has a glass transition temperature of an ordinary temperature or less so as to adjust the glass transition temperature of the entire product to a temperature slightly lower than the actual use temperature.
However, since the pressure-sensitive adhesive tape or sheet is used in various fields. In particular, in the case of the medical application, the beauty and health application, the sports application, or the like, since the adherend is a skin surface, strict conditions are applied to the demanded characteristics compared with the case of a pressure-sensitive adhesive tape or sheet to be bonded on a surface other than an organism surface. That is, since the skin surface state differs individually, the bonding state differs largely for a person with dry skin and a person with oily skin even in the case the same adhesive tape or sheet is used. Moreover, it differs also depending on the attachment position. In the case of attaching on a bending part such as an elbow or knee joint, or on a finger, a higher skin adhesive property is required. Furthermore, the excellent adhesive property with respect to bathing, kitchen work, perspiration, or the like (water proof adhesive property) is required as well as adjustment is necessary so as not to fluctuate the adhesive force in a low temperature of winter. That is, since the pressure-sensitive adhesive tape or sheet to be attached on the skin surface is used in most cases in a severer condition with respect to an ordinary adhesive tape or sheet, development of a pressure-sensitive adhesive composition having a higher adhesive force, capable of satisfying the need is keenly called for.
As a method for improving the adhesive force and the adhesion force, addition of a tackifier can be presented. However, in the case the tackifier is contained by a large amount, the glass transition temperature of the entire product is raised as mentioned above so that the adhesion force tends to be lowered in a low temperature. Moreover, since the tackifier has a relatively low molecular weight of several hundreds to several thousands, in the case it is contained by a large amount, it may be bloomed from a pressure-sensitive adhesive layer and transferred into a backing film so as to wet the backing film and generate wrinkles in the film.
In contrast, JP-W-8-506127 (published Japanese translation of PCT international publication) discloses a proposal for balancing the adhesion characteristic without containing a tackifier. It is for maintaining the adhesion characteristic only with a rubber component that is solid in an ordinary temperature and a liquid rubber component without containing a tackifier. By containing the liquid rubber component instead of the tackifier, the entire product is plasticized so as to lower the glass transition temperature, and improve the adhesive property with respect to an adherend. However, the cohesive force in the pressure-sensitive adhesive layer tends to be lowered, and it becomes too soft in an ordinary temperature. Therefore, for example, cohesive failure, adhesion residue of the pressure-sensitive adhesive component remained on an adherend, or the like are generated. Accordingly, a pressure-sensitive adhesive composition having a relatively sticky feeling is provided.
SUMMARY OF THE INVENTION
In order to solve the problems of the related art, the invention has been achieved. An object thereof is to provide a pressure-sensitive adhesive composition with the adhesive force, the cohesive force, and the anchoring force balanced, having the excellent low temperature characteristic and water proof characteristic, without the problem of the sticky feeling in the conventional rubber based adhesives, without the risk of swelling a backing film, and a pressure-sensitive adhesive tape or sheet using the same.
As a result of the elaborate discussion of the present inventors for achieving the object, it was found out that a pressure-sensitive adhesive composition having the excellent adhesion characteristic, which is not found in the conventional rubber based adhesives can be obtained by containing a rubber component that is solid in an ordinary temperature, a liquid rubber component, and a tackifier by a specific composition ratio so that the invention has been completed.
That is, the invention is to provide a pressure-sensitive adhesive composition containing 30 to 170 parts by weight of a rubber component that is liquid in an ordinary temperature (e.g., 25° C.), and 50 to 400 parts by weight of a tackifier with respect to 100 parts by weight of a rubber component that is solid in an ordinary temperature (e.g., 25° C.), wherein the tackifier is contained in a range of 25 to 80 parts by weight with respect to 100 parts by weight of the total rubber component amount.
Moreover, the invention is to provide a pressure-sensitive adhesive tape or sheet comprising the pressure-sensitive adhesive composition according laminated on one side of a backing film.
DETAILED DESCRIPTION OF THE INVENTION
A pressure-sensitive adhesive composition according to the invention contains a rubber component that is solid in an ordinary temperature, a rubber component that is liquid in an ordinary temperature, and a tackifier as the essential components. The effect of the invention cannot be performed without any of the components.
The rubber component that is solid in an ordinary temperature to be used in the invention serves as a base polymer for a pressure-sensitive adhesive composition. For example, an A-B type block copolymer, an A-B-A type block copolymer, or the like can be used. As the A-B type block copolymer, specifically, block copolymers such as a styrene-butadiene block copolymer, and a styrene-isoprene block copolymer can be used. A block copolymer
Kasahara Tsuyoshi
Kuniya Masayoshi
Sasaki Yasuyuki
Nitto Denko Corporation
Sanders Kriellion A.
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